Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/g1/concurrentMark.cpp @ 1835:4805b9f4779e
6941395: G1: Use only lock-free versions of region stack push() and pop()
Summary: Re-enable use of the lock-free versions of region stack push() and pop() by recording aborted regions in a thread-local structure, which are then processed when scanning of the region stack restarts. The previous locking versions of these routines are retained for diagnostic purposes.
Reviewed-by: tonyp, ysr
author | johnc |
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date | Tue, 28 Sep 2010 09:51:37 -0700 |
parents | 8b10f48633dc |
children | a5c514e74487 |
rev | line source |
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342 | 1 /* |
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2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved. |
342 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
4 * | |
5 * This code is free software; you can redistribute it and/or modify it | |
6 * under the terms of the GNU General Public License version 2 only, as | |
7 * published by the Free Software Foundation. | |
8 * | |
9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
12 * version 2 for more details (a copy is included in the LICENSE file that | |
13 * accompanied this code). | |
14 * | |
15 * You should have received a copy of the GNU General Public License version | |
16 * 2 along with this work; if not, write to the Free Software Foundation, | |
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
18 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
342 | 22 * |
23 */ | |
24 | |
25 #include "incls/_precompiled.incl" | |
26 #include "incls/_concurrentMark.cpp.incl" | |
27 | |
28 // | |
29 // CMS Bit Map Wrapper | |
30 | |
31 CMBitMapRO::CMBitMapRO(ReservedSpace rs, int shifter): | |
32 _bm((uintptr_t*)NULL,0), | |
33 _shifter(shifter) { | |
34 _bmStartWord = (HeapWord*)(rs.base()); | |
35 _bmWordSize = rs.size()/HeapWordSize; // rs.size() is in bytes | |
36 ReservedSpace brs(ReservedSpace::allocation_align_size_up( | |
37 (_bmWordSize >> (_shifter + LogBitsPerByte)) + 1)); | |
38 | |
39 guarantee(brs.is_reserved(), "couldn't allocate CMS bit map"); | |
40 // For now we'll just commit all of the bit map up fromt. | |
41 // Later on we'll try to be more parsimonious with swap. | |
42 guarantee(_virtual_space.initialize(brs, brs.size()), | |
43 "couldn't reseve backing store for CMS bit map"); | |
44 assert(_virtual_space.committed_size() == brs.size(), | |
45 "didn't reserve backing store for all of CMS bit map?"); | |
46 _bm.set_map((uintptr_t*)_virtual_space.low()); | |
47 assert(_virtual_space.committed_size() << (_shifter + LogBitsPerByte) >= | |
48 _bmWordSize, "inconsistency in bit map sizing"); | |
49 _bm.set_size(_bmWordSize >> _shifter); | |
50 } | |
51 | |
52 HeapWord* CMBitMapRO::getNextMarkedWordAddress(HeapWord* addr, | |
53 HeapWord* limit) const { | |
54 // First we must round addr *up* to a possible object boundary. | |
55 addr = (HeapWord*)align_size_up((intptr_t)addr, | |
56 HeapWordSize << _shifter); | |
57 size_t addrOffset = heapWordToOffset(addr); | |
58 if (limit == NULL) limit = _bmStartWord + _bmWordSize; | |
59 size_t limitOffset = heapWordToOffset(limit); | |
60 size_t nextOffset = _bm.get_next_one_offset(addrOffset, limitOffset); | |
61 HeapWord* nextAddr = offsetToHeapWord(nextOffset); | |
62 assert(nextAddr >= addr, "get_next_one postcondition"); | |
63 assert(nextAddr == limit || isMarked(nextAddr), | |
64 "get_next_one postcondition"); | |
65 return nextAddr; | |
66 } | |
67 | |
68 HeapWord* CMBitMapRO::getNextUnmarkedWordAddress(HeapWord* addr, | |
69 HeapWord* limit) const { | |
70 size_t addrOffset = heapWordToOffset(addr); | |
71 if (limit == NULL) limit = _bmStartWord + _bmWordSize; | |
72 size_t limitOffset = heapWordToOffset(limit); | |
73 size_t nextOffset = _bm.get_next_zero_offset(addrOffset, limitOffset); | |
74 HeapWord* nextAddr = offsetToHeapWord(nextOffset); | |
75 assert(nextAddr >= addr, "get_next_one postcondition"); | |
76 assert(nextAddr == limit || !isMarked(nextAddr), | |
77 "get_next_one postcondition"); | |
78 return nextAddr; | |
79 } | |
80 | |
81 int CMBitMapRO::heapWordDiffToOffsetDiff(size_t diff) const { | |
82 assert((diff & ((1 << _shifter) - 1)) == 0, "argument check"); | |
83 return (int) (diff >> _shifter); | |
84 } | |
85 | |
86 bool CMBitMapRO::iterate(BitMapClosure* cl, MemRegion mr) { | |
87 HeapWord* left = MAX2(_bmStartWord, mr.start()); | |
88 HeapWord* right = MIN2(_bmStartWord + _bmWordSize, mr.end()); | |
89 if (right > left) { | |
90 // Right-open interval [leftOffset, rightOffset). | |
91 return _bm.iterate(cl, heapWordToOffset(left), heapWordToOffset(right)); | |
92 } else { | |
93 return true; | |
94 } | |
95 } | |
96 | |
97 void CMBitMapRO::mostly_disjoint_range_union(BitMap* from_bitmap, | |
98 size_t from_start_index, | |
99 HeapWord* to_start_word, | |
100 size_t word_num) { | |
101 _bm.mostly_disjoint_range_union(from_bitmap, | |
102 from_start_index, | |
103 heapWordToOffset(to_start_word), | |
104 word_num); | |
105 } | |
106 | |
107 #ifndef PRODUCT | |
108 bool CMBitMapRO::covers(ReservedSpace rs) const { | |
109 // assert(_bm.map() == _virtual_space.low(), "map inconsistency"); | |
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110 assert(((size_t)_bm.size() * (size_t)(1 << _shifter)) == _bmWordSize, |
342 | 111 "size inconsistency"); |
112 return _bmStartWord == (HeapWord*)(rs.base()) && | |
113 _bmWordSize == rs.size()>>LogHeapWordSize; | |
114 } | |
115 #endif | |
116 | |
117 void CMBitMap::clearAll() { | |
118 _bm.clear(); | |
119 return; | |
120 } | |
121 | |
122 void CMBitMap::markRange(MemRegion mr) { | |
123 mr.intersection(MemRegion(_bmStartWord, _bmWordSize)); | |
124 assert(!mr.is_empty(), "unexpected empty region"); | |
125 assert((offsetToHeapWord(heapWordToOffset(mr.end())) == | |
126 ((HeapWord *) mr.end())), | |
127 "markRange memory region end is not card aligned"); | |
128 // convert address range into offset range | |
129 _bm.at_put_range(heapWordToOffset(mr.start()), | |
130 heapWordToOffset(mr.end()), true); | |
131 } | |
132 | |
133 void CMBitMap::clearRange(MemRegion mr) { | |
134 mr.intersection(MemRegion(_bmStartWord, _bmWordSize)); | |
135 assert(!mr.is_empty(), "unexpected empty region"); | |
136 // convert address range into offset range | |
137 _bm.at_put_range(heapWordToOffset(mr.start()), | |
138 heapWordToOffset(mr.end()), false); | |
139 } | |
140 | |
141 MemRegion CMBitMap::getAndClearMarkedRegion(HeapWord* addr, | |
142 HeapWord* end_addr) { | |
143 HeapWord* start = getNextMarkedWordAddress(addr); | |
144 start = MIN2(start, end_addr); | |
145 HeapWord* end = getNextUnmarkedWordAddress(start); | |
146 end = MIN2(end, end_addr); | |
147 assert(start <= end, "Consistency check"); | |
148 MemRegion mr(start, end); | |
149 if (!mr.is_empty()) { | |
150 clearRange(mr); | |
151 } | |
152 return mr; | |
153 } | |
154 | |
155 CMMarkStack::CMMarkStack(ConcurrentMark* cm) : | |
156 _base(NULL), _cm(cm) | |
157 #ifdef ASSERT | |
158 , _drain_in_progress(false) | |
159 , _drain_in_progress_yields(false) | |
160 #endif | |
161 {} | |
162 | |
163 void CMMarkStack::allocate(size_t size) { | |
164 _base = NEW_C_HEAP_ARRAY(oop, size); | |
165 if (_base == NULL) | |
166 vm_exit_during_initialization("Failed to allocate " | |
167 "CM region mark stack"); | |
168 _index = 0; | |
169 // QQQQ cast ... | |
170 _capacity = (jint) size; | |
171 _oops_do_bound = -1; | |
172 NOT_PRODUCT(_max_depth = 0); | |
173 } | |
174 | |
175 CMMarkStack::~CMMarkStack() { | |
176 if (_base != NULL) FREE_C_HEAP_ARRAY(oop, _base); | |
177 } | |
178 | |
179 void CMMarkStack::par_push(oop ptr) { | |
180 while (true) { | |
181 if (isFull()) { | |
182 _overflow = true; | |
183 return; | |
184 } | |
185 // Otherwise... | |
186 jint index = _index; | |
187 jint next_index = index+1; | |
188 jint res = Atomic::cmpxchg(next_index, &_index, index); | |
189 if (res == index) { | |
190 _base[index] = ptr; | |
191 // Note that we don't maintain this atomically. We could, but it | |
192 // doesn't seem necessary. | |
193 NOT_PRODUCT(_max_depth = MAX2(_max_depth, next_index)); | |
194 return; | |
195 } | |
196 // Otherwise, we need to try again. | |
197 } | |
198 } | |
199 | |
200 void CMMarkStack::par_adjoin_arr(oop* ptr_arr, int n) { | |
201 while (true) { | |
202 if (isFull()) { | |
203 _overflow = true; | |
204 return; | |
205 } | |
206 // Otherwise... | |
207 jint index = _index; | |
208 jint next_index = index + n; | |
209 if (next_index > _capacity) { | |
210 _overflow = true; | |
211 return; | |
212 } | |
213 jint res = Atomic::cmpxchg(next_index, &_index, index); | |
214 if (res == index) { | |
215 for (int i = 0; i < n; i++) { | |
216 int ind = index + i; | |
217 assert(ind < _capacity, "By overflow test above."); | |
218 _base[ind] = ptr_arr[i]; | |
219 } | |
220 NOT_PRODUCT(_max_depth = MAX2(_max_depth, next_index)); | |
221 return; | |
222 } | |
223 // Otherwise, we need to try again. | |
224 } | |
225 } | |
226 | |
227 | |
228 void CMMarkStack::par_push_arr(oop* ptr_arr, int n) { | |
229 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); | |
230 jint start = _index; | |
231 jint next_index = start + n; | |
232 if (next_index > _capacity) { | |
233 _overflow = true; | |
234 return; | |
235 } | |
236 // Otherwise. | |
237 _index = next_index; | |
238 for (int i = 0; i < n; i++) { | |
239 int ind = start + i; | |
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240 assert(ind < _capacity, "By overflow test above."); |
342 | 241 _base[ind] = ptr_arr[i]; |
242 } | |
243 } | |
244 | |
245 | |
246 bool CMMarkStack::par_pop_arr(oop* ptr_arr, int max, int* n) { | |
247 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); | |
248 jint index = _index; | |
249 if (index == 0) { | |
250 *n = 0; | |
251 return false; | |
252 } else { | |
253 int k = MIN2(max, index); | |
254 jint new_ind = index - k; | |
255 for (int j = 0; j < k; j++) { | |
256 ptr_arr[j] = _base[new_ind + j]; | |
257 } | |
258 _index = new_ind; | |
259 *n = k; | |
260 return true; | |
261 } | |
262 } | |
263 | |
264 | |
265 CMRegionStack::CMRegionStack() : _base(NULL) {} | |
266 | |
267 void CMRegionStack::allocate(size_t size) { | |
268 _base = NEW_C_HEAP_ARRAY(MemRegion, size); | |
269 if (_base == NULL) | |
270 vm_exit_during_initialization("Failed to allocate " | |
271 "CM region mark stack"); | |
272 _index = 0; | |
273 // QQQQ cast ... | |
274 _capacity = (jint) size; | |
275 } | |
276 | |
277 CMRegionStack::~CMRegionStack() { | |
278 if (_base != NULL) FREE_C_HEAP_ARRAY(oop, _base); | |
279 } | |
280 | |
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281 void CMRegionStack::push_lock_free(MemRegion mr) { |
342 | 282 assert(mr.word_size() > 0, "Precondition"); |
283 while (true) { | |
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284 jint index = _index; |
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285 |
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286 if (index >= _capacity) { |
342 | 287 _overflow = true; |
288 return; | |
289 } | |
290 // Otherwise... | |
291 jint next_index = index+1; | |
292 jint res = Atomic::cmpxchg(next_index, &_index, index); | |
293 if (res == index) { | |
294 _base[index] = mr; | |
295 return; | |
296 } | |
297 // Otherwise, we need to try again. | |
298 } | |
299 } | |
300 | |
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301 // Lock-free pop of the region stack. Called during the concurrent |
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302 // marking / remark phases. Should only be called in tandem with |
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303 // other lock-free pops. |
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304 MemRegion CMRegionStack::pop_lock_free() { |
342 | 305 while (true) { |
306 jint index = _index; | |
307 | |
308 if (index == 0) { | |
309 return MemRegion(); | |
310 } | |
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311 // Otherwise... |
342 | 312 jint next_index = index-1; |
313 jint res = Atomic::cmpxchg(next_index, &_index, index); | |
314 if (res == index) { | |
315 MemRegion mr = _base[next_index]; | |
316 if (mr.start() != NULL) { | |
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317 assert(mr.end() != NULL, "invariant"); |
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318 assert(mr.word_size() > 0, "invariant"); |
342 | 319 return mr; |
320 } else { | |
321 // that entry was invalidated... let's skip it | |
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322 assert(mr.end() == NULL, "invariant"); |
342 | 323 } |
324 } | |
325 // Otherwise, we need to try again. | |
326 } | |
327 } | |
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328 |
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329 #if 0 |
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330 // The routines that manipulate the region stack with a lock are |
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331 // not currently used. They should be retained, however, as a |
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332 // diagnostic aid. |
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333 |
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334 void CMRegionStack::push_with_lock(MemRegion mr) { |
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335 assert(mr.word_size() > 0, "Precondition"); |
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336 MutexLockerEx x(CMRegionStack_lock, Mutex::_no_safepoint_check_flag); |
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337 |
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338 if (isFull()) { |
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339 _overflow = true; |
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340 return; |
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341 } |
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342 |
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343 _base[_index] = mr; |
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344 _index += 1; |
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345 } |
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346 |
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347 MemRegion CMRegionStack::pop_with_lock() { |
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348 MutexLockerEx x(CMRegionStack_lock, Mutex::_no_safepoint_check_flag); |
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349 |
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350 while (true) { |
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351 if (_index == 0) { |
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352 return MemRegion(); |
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353 } |
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354 _index -= 1; |
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355 |
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356 MemRegion mr = _base[_index]; |
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357 if (mr.start() != NULL) { |
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358 assert(mr.end() != NULL, "invariant"); |
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359 assert(mr.word_size() > 0, "invariant"); |
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360 return mr; |
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361 } else { |
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362 // that entry was invalidated... let's skip it |
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363 assert(mr.end() == NULL, "invariant"); |
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364 } |
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365 } |
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366 } |
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367 #endif |
342 | 368 |
369 bool CMRegionStack::invalidate_entries_into_cset() { | |
370 bool result = false; | |
371 G1CollectedHeap* g1h = G1CollectedHeap::heap(); | |
372 for (int i = 0; i < _oops_do_bound; ++i) { | |
373 MemRegion mr = _base[i]; | |
374 if (mr.start() != NULL) { | |
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375 assert(mr.end() != NULL, "invariant"); |
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376 assert(mr.word_size() > 0, "invariant"); |
342 | 377 HeapRegion* hr = g1h->heap_region_containing(mr.start()); |
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378 assert(hr != NULL, "invariant"); |
342 | 379 if (hr->in_collection_set()) { |
380 // The region points into the collection set | |
381 _base[i] = MemRegion(); | |
382 result = true; | |
383 } | |
384 } else { | |
385 // that entry was invalidated... let's skip it | |
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386 assert(mr.end() == NULL, "invariant"); |
342 | 387 } |
388 } | |
389 return result; | |
390 } | |
391 | |
392 template<class OopClosureClass> | |
393 bool CMMarkStack::drain(OopClosureClass* cl, CMBitMap* bm, bool yield_after) { | |
394 assert(!_drain_in_progress || !_drain_in_progress_yields || yield_after | |
395 || SafepointSynchronize::is_at_safepoint(), | |
396 "Drain recursion must be yield-safe."); | |
397 bool res = true; | |
398 debug_only(_drain_in_progress = true); | |
399 debug_only(_drain_in_progress_yields = yield_after); | |
400 while (!isEmpty()) { | |
401 oop newOop = pop(); | |
402 assert(G1CollectedHeap::heap()->is_in_reserved(newOop), "Bad pop"); | |
403 assert(newOop->is_oop(), "Expected an oop"); | |
404 assert(bm == NULL || bm->isMarked((HeapWord*)newOop), | |
405 "only grey objects on this stack"); | |
406 // iterate over the oops in this oop, marking and pushing | |
407 // the ones in CMS generation. | |
408 newOop->oop_iterate(cl); | |
409 if (yield_after && _cm->do_yield_check()) { | |
410 res = false; break; | |
411 } | |
412 } | |
413 debug_only(_drain_in_progress = false); | |
414 return res; | |
415 } | |
416 | |
417 void CMMarkStack::oops_do(OopClosure* f) { | |
418 if (_index == 0) return; | |
419 assert(_oops_do_bound != -1 && _oops_do_bound <= _index, | |
420 "Bound must be set."); | |
421 for (int i = 0; i < _oops_do_bound; i++) { | |
422 f->do_oop(&_base[i]); | |
423 } | |
424 _oops_do_bound = -1; | |
425 } | |
426 | |
427 bool ConcurrentMark::not_yet_marked(oop obj) const { | |
428 return (_g1h->is_obj_ill(obj) | |
429 || (_g1h->is_in_permanent(obj) | |
430 && !nextMarkBitMap()->isMarked((HeapWord*)obj))); | |
431 } | |
432 | |
433 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away | |
434 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list | |
435 #endif // _MSC_VER | |
436 | |
437 ConcurrentMark::ConcurrentMark(ReservedSpace rs, | |
438 int max_regions) : | |
439 _markBitMap1(rs, MinObjAlignment - 1), | |
440 _markBitMap2(rs, MinObjAlignment - 1), | |
441 | |
442 _parallel_marking_threads(0), | |
443 _sleep_factor(0.0), | |
444 _marking_task_overhead(1.0), | |
445 _cleanup_sleep_factor(0.0), | |
446 _cleanup_task_overhead(1.0), | |
447 _region_bm(max_regions, false /* in_resource_area*/), | |
448 _card_bm((rs.size() + CardTableModRefBS::card_size - 1) >> | |
449 CardTableModRefBS::card_shift, | |
450 false /* in_resource_area*/), | |
451 _prevMarkBitMap(&_markBitMap1), | |
452 _nextMarkBitMap(&_markBitMap2), | |
453 _at_least_one_mark_complete(false), | |
454 | |
455 _markStack(this), | |
456 _regionStack(), | |
457 // _finger set in set_non_marking_state | |
458 | |
459 _max_task_num(MAX2(ParallelGCThreads, (size_t)1)), | |
460 // _active_tasks set in set_non_marking_state | |
461 // _tasks set inside the constructor | |
462 _task_queues(new CMTaskQueueSet((int) _max_task_num)), | |
463 _terminator(ParallelTaskTerminator((int) _max_task_num, _task_queues)), | |
464 | |
465 _has_overflown(false), | |
466 _concurrent(false), | |
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467 _has_aborted(false), |
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468 _restart_for_overflow(false), |
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469 _concurrent_marking_in_progress(false), |
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470 _should_gray_objects(false), |
342 | 471 |
472 // _verbose_level set below | |
473 | |
474 _init_times(), | |
475 _remark_times(), _remark_mark_times(), _remark_weak_ref_times(), | |
476 _cleanup_times(), | |
477 _total_counting_time(0.0), | |
478 _total_rs_scrub_time(0.0), | |
479 | |
936 | 480 _parallel_workers(NULL) |
342 | 481 { |
482 CMVerboseLevel verbose_level = | |
483 (CMVerboseLevel) G1MarkingVerboseLevel; | |
484 if (verbose_level < no_verbose) | |
485 verbose_level = no_verbose; | |
486 if (verbose_level > high_verbose) | |
487 verbose_level = high_verbose; | |
488 _verbose_level = verbose_level; | |
489 | |
490 if (verbose_low()) | |
491 gclog_or_tty->print_cr("[global] init, heap start = "PTR_FORMAT", " | |
492 "heap end = "PTR_FORMAT, _heap_start, _heap_end); | |
493 | |
1284 | 494 _markStack.allocate(MarkStackSize); |
751 | 495 _regionStack.allocate(G1MarkRegionStackSize); |
342 | 496 |
497 // Create & start a ConcurrentMark thread. | |
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498 _cmThread = new ConcurrentMarkThread(this); |
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499 assert(cmThread() != NULL, "CM Thread should have been created"); |
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500 assert(cmThread()->cm() != NULL, "CM Thread should refer to this cm"); |
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501 |
342 | 502 _g1h = G1CollectedHeap::heap(); |
503 assert(CGC_lock != NULL, "Where's the CGC_lock?"); | |
504 assert(_markBitMap1.covers(rs), "_markBitMap1 inconsistency"); | |
505 assert(_markBitMap2.covers(rs), "_markBitMap2 inconsistency"); | |
506 | |
507 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set(); | |
1282 | 508 satb_qs.set_buffer_size(G1SATBBufferSize); |
342 | 509 |
510 int size = (int) MAX2(ParallelGCThreads, (size_t)1); | |
511 _par_cleanup_thread_state = NEW_C_HEAP_ARRAY(ParCleanupThreadState*, size); | |
512 for (int i = 0 ; i < size; i++) { | |
513 _par_cleanup_thread_state[i] = new ParCleanupThreadState; | |
514 } | |
515 | |
516 _tasks = NEW_C_HEAP_ARRAY(CMTask*, _max_task_num); | |
517 _accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_task_num); | |
518 | |
519 // so that the assertion in MarkingTaskQueue::task_queue doesn't fail | |
520 _active_tasks = _max_task_num; | |
521 for (int i = 0; i < (int) _max_task_num; ++i) { | |
522 CMTaskQueue* task_queue = new CMTaskQueue(); | |
523 task_queue->initialize(); | |
524 _task_queues->register_queue(i, task_queue); | |
525 | |
526 _tasks[i] = new CMTask(i, this, task_queue, _task_queues); | |
527 _accum_task_vtime[i] = 0.0; | |
528 } | |
529 | |
1284 | 530 if (ConcGCThreads > ParallelGCThreads) { |
531 vm_exit_during_initialization("Can't have more ConcGCThreads " | |
342 | 532 "than ParallelGCThreads."); |
533 } | |
534 if (ParallelGCThreads == 0) { | |
535 // if we are not running with any parallel GC threads we will not | |
536 // spawn any marking threads either | |
537 _parallel_marking_threads = 0; | |
538 _sleep_factor = 0.0; | |
539 _marking_task_overhead = 1.0; | |
540 } else { | |
1284 | 541 if (ConcGCThreads > 0) { |
542 // notice that ConcGCThreads overwrites G1MarkingOverheadPercent | |
342 | 543 // if both are set |
544 | |
1284 | 545 _parallel_marking_threads = ConcGCThreads; |
342 | 546 _sleep_factor = 0.0; |
547 _marking_task_overhead = 1.0; | |
751 | 548 } else if (G1MarkingOverheadPercent > 0) { |
342 | 549 // we will calculate the number of parallel marking threads |
550 // based on a target overhead with respect to the soft real-time | |
551 // goal | |
552 | |
751 | 553 double marking_overhead = (double) G1MarkingOverheadPercent / 100.0; |
342 | 554 double overall_cm_overhead = |
751 | 555 (double) MaxGCPauseMillis * marking_overhead / |
556 (double) GCPauseIntervalMillis; | |
342 | 557 double cpu_ratio = 1.0 / (double) os::processor_count(); |
558 double marking_thread_num = ceil(overall_cm_overhead / cpu_ratio); | |
559 double marking_task_overhead = | |
560 overall_cm_overhead / marking_thread_num * | |
561 (double) os::processor_count(); | |
562 double sleep_factor = | |
563 (1.0 - marking_task_overhead) / marking_task_overhead; | |
564 | |
565 _parallel_marking_threads = (size_t) marking_thread_num; | |
566 _sleep_factor = sleep_factor; | |
567 _marking_task_overhead = marking_task_overhead; | |
568 } else { | |
569 _parallel_marking_threads = MAX2((ParallelGCThreads + 2) / 4, (size_t)1); | |
570 _sleep_factor = 0.0; | |
571 _marking_task_overhead = 1.0; | |
572 } | |
573 | |
574 if (parallel_marking_threads() > 1) | |
575 _cleanup_task_overhead = 1.0; | |
576 else | |
577 _cleanup_task_overhead = marking_task_overhead(); | |
578 _cleanup_sleep_factor = | |
579 (1.0 - cleanup_task_overhead()) / cleanup_task_overhead(); | |
580 | |
581 #if 0 | |
582 gclog_or_tty->print_cr("Marking Threads %d", parallel_marking_threads()); | |
583 gclog_or_tty->print_cr("CM Marking Task Overhead %1.4lf", marking_task_overhead()); | |
584 gclog_or_tty->print_cr("CM Sleep Factor %1.4lf", sleep_factor()); | |
585 gclog_or_tty->print_cr("CL Marking Task Overhead %1.4lf", cleanup_task_overhead()); | |
586 gclog_or_tty->print_cr("CL Sleep Factor %1.4lf", cleanup_sleep_factor()); | |
587 #endif | |
588 | |
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589 guarantee(parallel_marking_threads() > 0, "peace of mind"); |
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590 _parallel_workers = new FlexibleWorkGang("G1 Parallel Marking Threads", |
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591 (int) _parallel_marking_threads, false, true); |
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592 if (_parallel_workers == NULL) { |
342 | 593 vm_exit_during_initialization("Failed necessary allocation."); |
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594 } else { |
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595 _parallel_workers->initialize_workers(); |
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596 } |
342 | 597 } |
598 | |
599 // so that the call below can read a sensible value | |
600 _heap_start = (HeapWord*) rs.base(); | |
601 set_non_marking_state(); | |
602 } | |
603 | |
604 void ConcurrentMark::update_g1_committed(bool force) { | |
605 // If concurrent marking is not in progress, then we do not need to | |
606 // update _heap_end. This has a subtle and important | |
607 // side-effect. Imagine that two evacuation pauses happen between | |
608 // marking completion and remark. The first one can grow the | |
609 // heap (hence now the finger is below the heap end). Then, the | |
610 // second one could unnecessarily push regions on the region | |
611 // stack. This causes the invariant that the region stack is empty | |
612 // at the beginning of remark to be false. By ensuring that we do | |
613 // not observe heap expansions after marking is complete, then we do | |
614 // not have this problem. | |
615 if (!concurrent_marking_in_progress() && !force) | |
616 return; | |
617 | |
618 MemRegion committed = _g1h->g1_committed(); | |
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619 assert(committed.start() == _heap_start, "start shouldn't change"); |
342 | 620 HeapWord* new_end = committed.end(); |
621 if (new_end > _heap_end) { | |
622 // The heap has been expanded. | |
623 | |
624 _heap_end = new_end; | |
625 } | |
626 // Notice that the heap can also shrink. However, this only happens | |
627 // during a Full GC (at least currently) and the entire marking | |
628 // phase will bail out and the task will not be restarted. So, let's | |
629 // do nothing. | |
630 } | |
631 | |
632 void ConcurrentMark::reset() { | |
633 // Starting values for these two. This should be called in a STW | |
634 // phase. CM will be notified of any future g1_committed expansions | |
635 // will be at the end of evacuation pauses, when tasks are | |
636 // inactive. | |
637 MemRegion committed = _g1h->g1_committed(); | |
638 _heap_start = committed.start(); | |
639 _heap_end = committed.end(); | |
640 | |
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641 // Separated the asserts so that we know which one fires. |
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642 assert(_heap_start != NULL, "heap bounds should look ok"); |
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643 assert(_heap_end != NULL, "heap bounds should look ok"); |
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644 assert(_heap_start < _heap_end, "heap bounds should look ok"); |
342 | 645 |
646 // reset all the marking data structures and any necessary flags | |
647 clear_marking_state(); | |
648 | |
649 if (verbose_low()) | |
650 gclog_or_tty->print_cr("[global] resetting"); | |
651 | |
652 // We do reset all of them, since different phases will use | |
653 // different number of active threads. So, it's easiest to have all | |
654 // of them ready. | |
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655 for (int i = 0; i < (int) _max_task_num; ++i) { |
342 | 656 _tasks[i]->reset(_nextMarkBitMap); |
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657 } |
342 | 658 |
659 // we need this to make sure that the flag is on during the evac | |
660 // pause with initial mark piggy-backed | |
661 set_concurrent_marking_in_progress(); | |
662 } | |
663 | |
664 void ConcurrentMark::set_phase(size_t active_tasks, bool concurrent) { | |
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665 assert(active_tasks <= _max_task_num, "we should not have more"); |
342 | 666 |
667 _active_tasks = active_tasks; | |
668 // Need to update the three data structures below according to the | |
669 // number of active threads for this phase. | |
670 _terminator = ParallelTaskTerminator((int) active_tasks, _task_queues); | |
671 _first_overflow_barrier_sync.set_n_workers((int) active_tasks); | |
672 _second_overflow_barrier_sync.set_n_workers((int) active_tasks); | |
673 | |
674 _concurrent = concurrent; | |
675 // We propagate this to all tasks, not just the active ones. | |
676 for (int i = 0; i < (int) _max_task_num; ++i) | |
677 _tasks[i]->set_concurrent(concurrent); | |
678 | |
679 if (concurrent) { | |
680 set_concurrent_marking_in_progress(); | |
681 } else { | |
682 // We currently assume that the concurrent flag has been set to | |
683 // false before we start remark. At this point we should also be | |
684 // in a STW phase. | |
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685 assert(!concurrent_marking_in_progress(), "invariant"); |
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686 assert(_finger == _heap_end, "only way to get here"); |
342 | 687 update_g1_committed(true); |
688 } | |
689 } | |
690 | |
691 void ConcurrentMark::set_non_marking_state() { | |
692 // We set the global marking state to some default values when we're | |
693 // not doing marking. | |
694 clear_marking_state(); | |
695 _active_tasks = 0; | |
696 clear_concurrent_marking_in_progress(); | |
697 } | |
698 | |
699 ConcurrentMark::~ConcurrentMark() { | |
700 int size = (int) MAX2(ParallelGCThreads, (size_t)1); | |
701 for (int i = 0; i < size; i++) delete _par_cleanup_thread_state[i]; | |
702 FREE_C_HEAP_ARRAY(ParCleanupThreadState*, | |
703 _par_cleanup_thread_state); | |
704 | |
705 for (int i = 0; i < (int) _max_task_num; ++i) { | |
706 delete _task_queues->queue(i); | |
707 delete _tasks[i]; | |
708 } | |
709 delete _task_queues; | |
710 FREE_C_HEAP_ARRAY(CMTask*, _max_task_num); | |
711 } | |
712 | |
713 // This closure is used to mark refs into the g1 generation | |
714 // from external roots in the CMS bit map. | |
715 // Called at the first checkpoint. | |
716 // | |
717 | |
718 void ConcurrentMark::clearNextBitmap() { | |
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719 G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
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720 G1CollectorPolicy* g1p = g1h->g1_policy(); |
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721 |
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722 // Make sure that the concurrent mark thread looks to still be in |
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723 // the current cycle. |
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724 guarantee(cmThread()->during_cycle(), "invariant"); |
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725 |
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726 // We are finishing up the current cycle by clearing the next |
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727 // marking bitmap and getting it ready for the next cycle. During |
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728 // this time no other cycle can start. So, let's make sure that this |
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729 // is the case. |
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730 guarantee(!g1h->mark_in_progress(), "invariant"); |
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731 |
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732 // clear the mark bitmap (no grey objects to start with). |
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733 // We need to do this in chunks and offer to yield in between |
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734 // each chunk. |
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735 HeapWord* start = _nextMarkBitMap->startWord(); |
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736 HeapWord* end = _nextMarkBitMap->endWord(); |
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737 HeapWord* cur = start; |
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738 size_t chunkSize = M; |
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739 while (cur < end) { |
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740 HeapWord* next = cur + chunkSize; |
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741 if (next > end) |
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742 next = end; |
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743 MemRegion mr(cur,next); |
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744 _nextMarkBitMap->clearRange(mr); |
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745 cur = next; |
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746 do_yield_check(); |
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747 |
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748 // Repeat the asserts from above. We'll do them as asserts here to |
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749 // minimize their overhead on the product. However, we'll have |
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750 // them as guarantees at the beginning / end of the bitmap |
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751 // clearing to get some checking in the product. |
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752 assert(cmThread()->during_cycle(), "invariant"); |
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753 assert(!g1h->mark_in_progress(), "invariant"); |
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754 } |
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755 |
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756 // Repeat the asserts from above. |
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757 guarantee(cmThread()->during_cycle(), "invariant"); |
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758 guarantee(!g1h->mark_in_progress(), "invariant"); |
342 | 759 } |
760 | |
761 class NoteStartOfMarkHRClosure: public HeapRegionClosure { | |
762 public: | |
763 bool doHeapRegion(HeapRegion* r) { | |
764 if (!r->continuesHumongous()) { | |
765 r->note_start_of_marking(true); | |
766 } | |
767 return false; | |
768 } | |
769 }; | |
770 | |
771 void ConcurrentMark::checkpointRootsInitialPre() { | |
772 G1CollectedHeap* g1h = G1CollectedHeap::heap(); | |
773 G1CollectorPolicy* g1p = g1h->g1_policy(); | |
774 | |
775 _has_aborted = false; | |
776 | |
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777 #ifndef PRODUCT |
1044 | 778 if (G1PrintReachableAtInitialMark) { |
1388 | 779 print_reachable("at-cycle-start", |
780 true /* use_prev_marking */, true /* all */); | |
1044 | 781 } |
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782 #endif |
342 | 783 |
784 // Initialise marking structures. This has to be done in a STW phase. | |
785 reset(); | |
786 } | |
787 | |
788 class CMMarkRootsClosure: public OopsInGenClosure { | |
789 private: | |
790 ConcurrentMark* _cm; | |
791 G1CollectedHeap* _g1h; | |
792 bool _do_barrier; | |
793 | |
794 public: | |
795 CMMarkRootsClosure(ConcurrentMark* cm, | |
796 G1CollectedHeap* g1h, | |
797 bool do_barrier) : _cm(cm), _g1h(g1h), | |
798 _do_barrier(do_barrier) { } | |
799 | |
845
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800 virtual void do_oop(narrowOop* p) { do_oop_work(p); } |
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801 virtual void do_oop( oop* p) { do_oop_work(p); } |
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802 |
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803 template <class T> void do_oop_work(T* p) { |
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804 T heap_oop = oopDesc::load_heap_oop(p); |
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805 if (!oopDesc::is_null(heap_oop)) { |
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806 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); |
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807 assert(obj->is_oop() || obj->mark() == NULL, |
342 | 808 "expected an oop, possibly with mark word displaced"); |
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809 HeapWord* addr = (HeapWord*)obj; |
342 | 810 if (_g1h->is_in_g1_reserved(addr)) { |
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811 _cm->grayRoot(obj); |
342 | 812 } |
813 } | |
814 if (_do_barrier) { | |
815 assert(!_g1h->is_in_g1_reserved(p), | |
816 "Should be called on external roots"); | |
817 do_barrier(p); | |
818 } | |
819 } | |
820 }; | |
821 | |
822 void ConcurrentMark::checkpointRootsInitialPost() { | |
823 G1CollectedHeap* g1h = G1CollectedHeap::heap(); | |
824 | |
825 // For each region note start of marking. | |
826 NoteStartOfMarkHRClosure startcl; | |
827 g1h->heap_region_iterate(&startcl); | |
828 | |
829 // Start weak-reference discovery. | |
830 ReferenceProcessor* rp = g1h->ref_processor(); | |
831 rp->verify_no_references_recorded(); | |
832 rp->enable_discovery(); // enable ("weak") refs discovery | |
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833 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle |
342 | 834 |
835 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set(); | |
1317
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836 // This is the start of the marking cycle, we're expected all |
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837 // threads to have SATB queues with active set to false. |
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838 satb_mq_set.set_active_all_threads(true, /* new active value */ |
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839 false /* expected_active */); |
342 | 840 |
841 // update_g1_committed() will be called at the end of an evac pause | |
842 // when marking is on. So, it's also called at the end of the | |
843 // initial-mark pause to update the heap end, if the heap expands | |
844 // during it. No need to call it here. | |
845 } | |
846 | |
847 // Checkpoint the roots into this generation from outside | |
848 // this generation. [Note this initial checkpoint need only | |
849 // be approximate -- we'll do a catch up phase subsequently.] | |
850 void ConcurrentMark::checkpointRootsInitial() { | |
851 assert(SafepointSynchronize::is_at_safepoint(), "world should be stopped"); | |
852 G1CollectedHeap* g1h = G1CollectedHeap::heap(); | |
853 | |
854 double start = os::elapsedTime(); | |
855 | |
856 G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy(); | |
857 g1p->record_concurrent_mark_init_start(); | |
858 checkpointRootsInitialPre(); | |
859 | |
860 // YSR: when concurrent precleaning is in place, we'll | |
861 // need to clear the cached card table here | |
862 | |
863 ResourceMark rm; | |
864 HandleMark hm; | |
865 | |
866 g1h->ensure_parsability(false); | |
867 g1h->perm_gen()->save_marks(); | |
868 | |
869 CMMarkRootsClosure notOlder(this, g1h, false); | |
870 CMMarkRootsClosure older(this, g1h, true); | |
871 | |
872 g1h->set_marking_started(); | |
873 g1h->rem_set()->prepare_for_younger_refs_iterate(false); | |
874 | |
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875 g1h->process_strong_roots(true, // activate StrongRootsScope |
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876 false, // fake perm gen collection |
342 | 877 SharedHeap::SO_AllClasses, |
878 ¬Older, // Regular roots | |
989
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879 NULL, // do not visit active blobs |
342 | 880 &older // Perm Gen Roots |
881 ); | |
882 checkpointRootsInitialPost(); | |
883 | |
884 // Statistics. | |
885 double end = os::elapsedTime(); | |
886 _init_times.add((end - start) * 1000.0); | |
887 | |
888 g1p->record_concurrent_mark_init_end(); | |
889 } | |
890 | |
891 /* | |
892 Notice that in the next two methods, we actually leave the STS | |
893 during the barrier sync and join it immediately afterwards. If we | |
894 do not do this, this then the following deadlock can occur: one | |
895 thread could be in the barrier sync code, waiting for the other | |
896 thread to also sync up, whereas another one could be trying to | |
897 yield, while also waiting for the other threads to sync up too. | |
898 | |
899 Because the thread that does the sync barrier has left the STS, it | |
900 is possible to be suspended for a Full GC or an evacuation pause | |
901 could occur. This is actually safe, since the entering the sync | |
902 barrier is one of the last things do_marking_step() does, and it | |
903 doesn't manipulate any data structures afterwards. | |
904 */ | |
905 | |
906 void ConcurrentMark::enter_first_sync_barrier(int task_num) { | |
907 if (verbose_low()) | |
908 gclog_or_tty->print_cr("[%d] entering first barrier", task_num); | |
909 | |
910 ConcurrentGCThread::stsLeave(); | |
911 _first_overflow_barrier_sync.enter(); | |
912 ConcurrentGCThread::stsJoin(); | |
913 // at this point everyone should have synced up and not be doing any | |
914 // more work | |
915 | |
916 if (verbose_low()) | |
917 gclog_or_tty->print_cr("[%d] leaving first barrier", task_num); | |
918 | |
919 // let task 0 do this | |
920 if (task_num == 0) { | |
921 // task 0 is responsible for clearing the global data structures | |
922 clear_marking_state(); | |
923 | |
924 if (PrintGC) { | |
925 gclog_or_tty->date_stamp(PrintGCDateStamps); | |
926 gclog_or_tty->stamp(PrintGCTimeStamps); | |
927 gclog_or_tty->print_cr("[GC concurrent-mark-reset-for-overflow]"); | |
928 } | |
929 } | |
930 | |
931 // after this, each task should reset its own data structures then | |
932 // then go into the second barrier | |
933 } | |
934 | |
935 void ConcurrentMark::enter_second_sync_barrier(int task_num) { | |
936 if (verbose_low()) | |
937 gclog_or_tty->print_cr("[%d] entering second barrier", task_num); | |
938 | |
939 ConcurrentGCThread::stsLeave(); | |
940 _second_overflow_barrier_sync.enter(); | |
941 ConcurrentGCThread::stsJoin(); | |
942 // at this point everything should be re-initialised and ready to go | |
943 | |
944 if (verbose_low()) | |
945 gclog_or_tty->print_cr("[%d] leaving second barrier", task_num); | |
946 } | |
947 | |
948 void ConcurrentMark::grayRoot(oop p) { | |
949 HeapWord* addr = (HeapWord*) p; | |
950 // We can't really check against _heap_start and _heap_end, since it | |
951 // is possible during an evacuation pause with piggy-backed | |
952 // initial-mark that the committed space is expanded during the | |
953 // pause without CM observing this change. So the assertions below | |
954 // is a bit conservative; but better than nothing. | |
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955 assert(_g1h->g1_committed().contains(addr), |
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956 "address should be within the heap bounds"); |
342 | 957 |
958 if (!_nextMarkBitMap->isMarked(addr)) | |
959 _nextMarkBitMap->parMark(addr); | |
960 } | |
961 | |
962 void ConcurrentMark::grayRegionIfNecessary(MemRegion mr) { | |
963 // The objects on the region have already been marked "in bulk" by | |
964 // the caller. We only need to decide whether to push the region on | |
965 // the region stack or not. | |
966 | |
967 if (!concurrent_marking_in_progress() || !_should_gray_objects) | |
968 // We're done with marking and waiting for remark. We do not need to | |
969 // push anything else on the region stack. | |
970 return; | |
971 | |
972 HeapWord* finger = _finger; | |
973 | |
974 if (verbose_low()) | |
975 gclog_or_tty->print_cr("[global] attempting to push " | |
976 "region ["PTR_FORMAT", "PTR_FORMAT"), finger is at " | |
977 PTR_FORMAT, mr.start(), mr.end(), finger); | |
978 | |
979 if (mr.start() < finger) { | |
980 // The finger is always heap region aligned and it is not possible | |
981 // for mr to span heap regions. | |
1023
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982 assert(mr.end() <= finger, "invariant"); |
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983 |
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984 // Separated the asserts so that we know which one fires. |
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985 assert(mr.start() <= mr.end(), |
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986 "region boundaries should fall within the committed space"); |
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987 assert(_heap_start <= mr.start(), |
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988 "region boundaries should fall within the committed space"); |
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989 assert(mr.end() <= _heap_end, |
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990 "region boundaries should fall within the committed space"); |
342 | 991 if (verbose_low()) |
992 gclog_or_tty->print_cr("[global] region ["PTR_FORMAT", "PTR_FORMAT") " | |
993 "below the finger, pushing it", | |
994 mr.start(), mr.end()); | |
995 | |
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996 if (!region_stack_push_lock_free(mr)) { |
342 | 997 if (verbose_low()) |
998 gclog_or_tty->print_cr("[global] region stack has overflown."); | |
999 } | |
1000 } | |
1001 } | |
1002 | |
1003 void ConcurrentMark::markAndGrayObjectIfNecessary(oop p) { | |
1004 // The object is not marked by the caller. We need to at least mark | |
1005 // it and maybe push in on the stack. | |
1006 | |
1007 HeapWord* addr = (HeapWord*)p; | |
1008 if (!_nextMarkBitMap->isMarked(addr)) { | |
1009 // We definitely need to mark it, irrespective whether we bail out | |
1010 // because we're done with marking. | |
1011 if (_nextMarkBitMap->parMark(addr)) { | |
1012 if (!concurrent_marking_in_progress() || !_should_gray_objects) | |
1013 // If we're done with concurrent marking and we're waiting for | |
1014 // remark, then we're not pushing anything on the stack. | |
1015 return; | |
1016 | |
1017 // No OrderAccess:store_load() is needed. It is implicit in the | |
1018 // CAS done in parMark(addr) above | |
1019 HeapWord* finger = _finger; | |
1020 | |
1021 if (addr < finger) { | |
1022 if (!mark_stack_push(oop(addr))) { | |
1023 if (verbose_low()) | |
1024 gclog_or_tty->print_cr("[global] global stack overflow " | |
1025 "during parMark"); | |
1026 } | |
1027 } | |
1028 } | |
1029 } | |
1030 } | |
1031 | |
1032 class CMConcurrentMarkingTask: public AbstractGangTask { | |
1033 private: | |
1034 ConcurrentMark* _cm; | |
1035 ConcurrentMarkThread* _cmt; | |
1036 | |
1037 public: | |
1038 void work(int worker_i) { | |
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1039 assert(Thread::current()->is_ConcurrentGC_thread(), |
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1040 "this should only be done by a conc GC thread"); |
342 | 1041 |
1042 double start_vtime = os::elapsedVTime(); | |
1043 | |
1044 ConcurrentGCThread::stsJoin(); | |
1045 | |
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1046 assert((size_t) worker_i < _cm->active_tasks(), "invariant"); |
342 | 1047 CMTask* the_task = _cm->task(worker_i); |
1048 the_task->record_start_time(); | |
1049 if (!_cm->has_aborted()) { | |
1050 do { | |
1051 double start_vtime_sec = os::elapsedVTime(); | |
1052 double start_time_sec = os::elapsedTime(); | |
1053 the_task->do_marking_step(10.0); | |
1054 double end_time_sec = os::elapsedTime(); | |
1055 double end_vtime_sec = os::elapsedVTime(); | |
1056 double elapsed_vtime_sec = end_vtime_sec - start_vtime_sec; | |
1057 double elapsed_time_sec = end_time_sec - start_time_sec; | |
1058 _cm->clear_has_overflown(); | |
1059 | |
1060 bool ret = _cm->do_yield_check(worker_i); | |
1061 | |
1062 jlong sleep_time_ms; | |
1063 if (!_cm->has_aborted() && the_task->has_aborted()) { | |
1064 sleep_time_ms = | |
1065 (jlong) (elapsed_vtime_sec * _cm->sleep_factor() * 1000.0); | |
1066 ConcurrentGCThread::stsLeave(); | |
1067 os::sleep(Thread::current(), sleep_time_ms, false); | |
1068 ConcurrentGCThread::stsJoin(); | |
1069 } | |
1070 double end_time2_sec = os::elapsedTime(); | |
1071 double elapsed_time2_sec = end_time2_sec - start_time_sec; | |
1072 | |
1073 #if 0 | |
1074 gclog_or_tty->print_cr("CM: elapsed %1.4lf ms, sleep %1.4lf ms, " | |
1075 "overhead %1.4lf", | |
1076 elapsed_vtime_sec * 1000.0, (double) sleep_time_ms, | |
1077 the_task->conc_overhead(os::elapsedTime()) * 8.0); | |
1078 gclog_or_tty->print_cr("elapsed time %1.4lf ms, time 2: %1.4lf ms", | |
1079 elapsed_time_sec * 1000.0, elapsed_time2_sec * 1000.0); | |
1080 #endif | |
1081 } while (!_cm->has_aborted() && the_task->has_aborted()); | |
1082 } | |
1083 the_task->record_end_time(); | |
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1084 guarantee(!the_task->has_aborted() || _cm->has_aborted(), "invariant"); |
342 | 1085 |
1086 ConcurrentGCThread::stsLeave(); | |
1087 | |
1088 double end_vtime = os::elapsedVTime(); | |
1089 _cm->update_accum_task_vtime(worker_i, end_vtime - start_vtime); | |
1090 } | |
1091 | |
1092 CMConcurrentMarkingTask(ConcurrentMark* cm, | |
1093 ConcurrentMarkThread* cmt) : | |
1094 AbstractGangTask("Concurrent Mark"), _cm(cm), _cmt(cmt) { } | |
1095 | |
1096 ~CMConcurrentMarkingTask() { } | |
1097 }; | |
1098 | |
1099 void ConcurrentMark::markFromRoots() { | |
1100 // we might be tempted to assert that: | |
1101 // assert(asynch == !SafepointSynchronize::is_at_safepoint(), | |
1102 // "inconsistent argument?"); | |
1103 // However that wouldn't be right, because it's possible that | |
1104 // a safepoint is indeed in progress as a younger generation | |
1105 // stop-the-world GC happens even as we mark in this generation. | |
1106 | |
1107 _restart_for_overflow = false; | |
1108 | |
1109 set_phase(MAX2((size_t) 1, parallel_marking_threads()), true); | |
1110 | |
1111 CMConcurrentMarkingTask markingTask(this, cmThread()); | |
1112 if (parallel_marking_threads() > 0) | |
1113 _parallel_workers->run_task(&markingTask); | |
1114 else | |
1115 markingTask.work(0); | |
1116 print_stats(); | |
1117 } | |
1118 | |
1119 void ConcurrentMark::checkpointRootsFinal(bool clear_all_soft_refs) { | |
1120 // world is stopped at this checkpoint | |
1121 assert(SafepointSynchronize::is_at_safepoint(), | |
1122 "world should be stopped"); | |
1123 G1CollectedHeap* g1h = G1CollectedHeap::heap(); | |
1124 | |
1125 // If a full collection has happened, we shouldn't do this. | |
1126 if (has_aborted()) { | |
1127 g1h->set_marking_complete(); // So bitmap clearing isn't confused | |
1128 return; | |
1129 } | |
1130 | |
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1131 if (VerifyDuringGC) { |
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1132 HandleMark hm; // handle scope |
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1133 gclog_or_tty->print(" VerifyDuringGC:(before)"); |
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1134 Universe::heap()->prepare_for_verify(); |
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1135 Universe::verify(true, false, true); |
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1136 } |
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1137 |
342 | 1138 G1CollectorPolicy* g1p = g1h->g1_policy(); |
1139 g1p->record_concurrent_mark_remark_start(); | |
1140 | |
1141 double start = os::elapsedTime(); | |
1142 | |
1143 checkpointRootsFinalWork(); | |
1144 | |
1145 double mark_work_end = os::elapsedTime(); | |
1146 | |
1147 weakRefsWork(clear_all_soft_refs); | |
1148 | |
1149 if (has_overflown()) { | |
1150 // Oops. We overflowed. Restart concurrent marking. | |
1151 _restart_for_overflow = true; | |
1152 // Clear the flag. We do not need it any more. | |
1153 clear_has_overflown(); | |
1154 if (G1TraceMarkStackOverflow) | |
1155 gclog_or_tty->print_cr("\nRemark led to restart for overflow."); | |
1156 } else { | |
1157 // We're done with marking. | |
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1158 // This is the end of the marking cycle, we're expected all |
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1159 // threads to have SATB queues with active set to true. |
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1160 JavaThread::satb_mark_queue_set().set_active_all_threads( |
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1161 false, /* new active value */ |
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1162 true /* expected_active */); |
811 | 1163 |
1164 if (VerifyDuringGC) { | |
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1165 HandleMark hm; // handle scope |
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1166 gclog_or_tty->print(" VerifyDuringGC:(after)"); |
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1167 Universe::heap()->prepare_for_verify(); |
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1168 Universe::heap()->verify(/* allow_dirty */ true, |
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1169 /* silent */ false, |
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1170 /* use_prev_marking */ false); |
811 | 1171 } |
342 | 1172 } |
1173 | |
1174 #if VERIFY_OBJS_PROCESSED | |
1175 _scan_obj_cl.objs_processed = 0; | |
1176 ThreadLocalObjQueue::objs_enqueued = 0; | |
1177 #endif | |
1178 | |
1179 // Statistics | |
1180 double now = os::elapsedTime(); | |
1181 _remark_mark_times.add((mark_work_end - start) * 1000.0); | |
1182 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0); | |
1183 _remark_times.add((now - start) * 1000.0); | |
1184 | |
1185 g1p->record_concurrent_mark_remark_end(); | |
1186 } | |
1187 | |
1188 | |
1189 #define CARD_BM_TEST_MODE 0 | |
1190 | |
1191 class CalcLiveObjectsClosure: public HeapRegionClosure { | |
1192 | |
1193 CMBitMapRO* _bm; | |
1194 ConcurrentMark* _cm; | |
1195 bool _changed; | |
1196 bool _yield; | |
1197 size_t _words_done; | |
1198 size_t _tot_live; | |
1199 size_t _tot_used; | |
1200 size_t _regions_done; | |
1201 double _start_vtime_sec; | |
1202 | |
1203 BitMap* _region_bm; | |
1204 BitMap* _card_bm; | |
1205 intptr_t _bottom_card_num; | |
1206 bool _final; | |
1207 | |
1208 void mark_card_num_range(intptr_t start_card_num, intptr_t last_card_num) { | |
1209 for (intptr_t i = start_card_num; i <= last_card_num; i++) { | |
1210 #if CARD_BM_TEST_MODE | |
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1211 guarantee(_card_bm->at(i - _bottom_card_num), "Should already be set."); |
342 | 1212 #else |
1213 _card_bm->par_at_put(i - _bottom_card_num, 1); | |
1214 #endif | |
1215 } | |
1216 } | |
1217 | |
1218 public: | |
1219 CalcLiveObjectsClosure(bool final, | |
1220 CMBitMapRO *bm, ConcurrentMark *cm, | |
936 | 1221 BitMap* region_bm, BitMap* card_bm) : |
342 | 1222 _bm(bm), _cm(cm), _changed(false), _yield(true), |
1223 _words_done(0), _tot_live(0), _tot_used(0), | |
936 | 1224 _region_bm(region_bm), _card_bm(card_bm),_final(final), |
342 | 1225 _regions_done(0), _start_vtime_sec(0.0) |
1226 { | |
1227 _bottom_card_num = | |
1228 intptr_t(uintptr_t(G1CollectedHeap::heap()->reserved_region().start()) >> | |
1229 CardTableModRefBS::card_shift); | |
1230 } | |
1231 | |
829 | 1232 // It takes a region that's not empty (i.e., it has at least one |
1233 // live object in it and sets its corresponding bit on the region | |
1234 // bitmap to 1. If the region is "starts humongous" it will also set | |
1235 // to 1 the bits on the region bitmap that correspond to its | |
1236 // associated "continues humongous" regions. | |
1237 void set_bit_for_region(HeapRegion* hr) { | |
1238 assert(!hr->continuesHumongous(), "should have filtered those out"); | |
1239 | |
1240 size_t index = hr->hrs_index(); | |
1241 if (!hr->startsHumongous()) { | |
1242 // Normal (non-humongous) case: just set the bit. | |
1243 _region_bm->par_at_put((BitMap::idx_t) index, true); | |
1244 } else { | |
1245 // Starts humongous case: calculate how many regions are part of | |
1246 // this humongous region and then set the bit range. It might | |
1247 // have been a bit more efficient to look at the object that | |
1248 // spans these humongous regions to calculate their number from | |
1249 // the object's size. However, it's a good idea to calculate | |
1250 // this based on the metadata itself, and not the region | |
1251 // contents, so that this code is not aware of what goes into | |
1252 // the humongous regions (in case this changes in the future). | |
1253 G1CollectedHeap* g1h = G1CollectedHeap::heap(); | |
1254 size_t end_index = index + 1; | |
831 | 1255 while (end_index < g1h->n_regions()) { |
1256 HeapRegion* chr = g1h->region_at(end_index); | |
829 | 1257 if (!chr->continuesHumongous()) { |
1258 break; | |
1259 } | |
1260 end_index += 1; | |
1261 } | |
1262 _region_bm->par_at_put_range((BitMap::idx_t) index, | |
1263 (BitMap::idx_t) end_index, true); | |
1264 } | |
1265 } | |
1266 | |
342 | 1267 bool doHeapRegion(HeapRegion* hr) { |
1268 if (!_final && _regions_done == 0) | |
1269 _start_vtime_sec = os::elapsedVTime(); | |
1270 | |
639 | 1271 if (hr->continuesHumongous()) { |
829 | 1272 // We will ignore these here and process them when their |
1273 // associated "starts humongous" region is processed (see | |
1274 // set_bit_for_heap_region()). Note that we cannot rely on their | |
1275 // associated "starts humongous" region to have their bit set to | |
1276 // 1 since, due to the region chunking in the parallel region | |
1277 // iteration, a "continues humongous" region might be visited | |
1278 // before its associated "starts humongous". | |
639 | 1279 return false; |
1280 } | |
342 | 1281 |
1282 HeapWord* nextTop = hr->next_top_at_mark_start(); | |
1283 HeapWord* start = hr->top_at_conc_mark_count(); | |
1284 assert(hr->bottom() <= start && start <= hr->end() && | |
1285 hr->bottom() <= nextTop && nextTop <= hr->end() && | |
1286 start <= nextTop, | |
1287 "Preconditions."); | |
1288 // Otherwise, record the number of word's we'll examine. | |
1289 size_t words_done = (nextTop - start); | |
1290 // Find the first marked object at or after "start". | |
1291 start = _bm->getNextMarkedWordAddress(start, nextTop); | |
1292 size_t marked_bytes = 0; | |
1293 | |
1294 // Below, the term "card num" means the result of shifting an address | |
1295 // by the card shift -- address 0 corresponds to card number 0. One | |
1296 // must subtract the card num of the bottom of the heap to obtain a | |
1297 // card table index. | |
1298 // The first card num of the sequence of live cards currently being | |
1299 // constructed. -1 ==> no sequence. | |
1300 intptr_t start_card_num = -1; | |
1301 // The last card num of the sequence of live cards currently being | |
1302 // constructed. -1 ==> no sequence. | |
1303 intptr_t last_card_num = -1; | |
1304 | |
1305 while (start < nextTop) { | |
1306 if (_yield && _cm->do_yield_check()) { | |
1307 // We yielded. It might be for a full collection, in which case | |
1308 // all bets are off; terminate the traversal. | |
1309 if (_cm->has_aborted()) { | |
1310 _changed = false; | |
1311 return true; | |
1312 } else { | |
1313 // Otherwise, it might be a collection pause, and the region | |
1314 // we're looking at might be in the collection set. We'll | |
1315 // abandon this region. | |
1316 return false; | |
1317 } | |
1318 } | |
1319 oop obj = oop(start); | |
1320 int obj_sz = obj->size(); | |
1321 // The card num of the start of the current object. | |
1322 intptr_t obj_card_num = | |
1323 intptr_t(uintptr_t(start) >> CardTableModRefBS::card_shift); | |
1324 | |
1325 HeapWord* obj_last = start + obj_sz - 1; | |
1326 intptr_t obj_last_card_num = | |
1327 intptr_t(uintptr_t(obj_last) >> CardTableModRefBS::card_shift); | |
1328 | |
1329 if (obj_card_num != last_card_num) { | |
1330 if (start_card_num == -1) { | |
1331 assert(last_card_num == -1, "Both or neither."); | |
1332 start_card_num = obj_card_num; | |
1333 } else { | |
1334 assert(last_card_num != -1, "Both or neither."); | |
1335 assert(obj_card_num >= last_card_num, "Inv"); | |
1336 if ((obj_card_num - last_card_num) > 1) { | |
1337 // Mark the last run, and start a new one. | |
1338 mark_card_num_range(start_card_num, last_card_num); | |
1339 start_card_num = obj_card_num; | |
1340 } | |
1341 } | |
1342 #if CARD_BM_TEST_MODE | |
1343 /* | |
1344 gclog_or_tty->print_cr("Setting bits from %d/%d.", | |
1345 obj_card_num - _bottom_card_num, | |
1346 obj_last_card_num - _bottom_card_num); | |
1347 */ | |
1348 for (intptr_t j = obj_card_num; j <= obj_last_card_num; j++) { | |
1349 _card_bm->par_at_put(j - _bottom_card_num, 1); | |
1350 } | |
1351 #endif | |
1352 } | |
1353 // In any case, we set the last card num. | |
1354 last_card_num = obj_last_card_num; | |
1355 | |
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1356 marked_bytes += (size_t)obj_sz * HeapWordSize; |
342 | 1357 // Find the next marked object after this one. |
1358 start = _bm->getNextMarkedWordAddress(start + 1, nextTop); | |
1359 _changed = true; | |
1360 } | |
1361 // Handle the last range, if any. | |
1362 if (start_card_num != -1) | |
1363 mark_card_num_range(start_card_num, last_card_num); | |
1364 if (_final) { | |
1365 // Mark the allocated-since-marking portion... | |
1366 HeapWord* tp = hr->top(); | |
1367 if (nextTop < tp) { | |
1368 start_card_num = | |
1369 intptr_t(uintptr_t(nextTop) >> CardTableModRefBS::card_shift); | |
1370 last_card_num = | |
1371 intptr_t(uintptr_t(tp) >> CardTableModRefBS::card_shift); | |
1372 mark_card_num_range(start_card_num, last_card_num); | |
1373 // This definitely means the region has live objects. | |
829 | 1374 set_bit_for_region(hr); |
342 | 1375 } |
1376 } | |
1377 | |
1378 hr->add_to_marked_bytes(marked_bytes); | |
1379 // Update the live region bitmap. | |
1380 if (marked_bytes > 0) { | |
829 | 1381 set_bit_for_region(hr); |
342 | 1382 } |
1383 hr->set_top_at_conc_mark_count(nextTop); | |
1384 _tot_live += hr->next_live_bytes(); | |
1385 _tot_used += hr->used(); | |
1386 _words_done = words_done; | |
1387 | |
1388 if (!_final) { | |
1389 ++_regions_done; | |
1390 if (_regions_done % 10 == 0) { | |
1391 double end_vtime_sec = os::elapsedVTime(); | |
1392 double elapsed_vtime_sec = end_vtime_sec - _start_vtime_sec; | |
1393 if (elapsed_vtime_sec > (10.0 / 1000.0)) { | |
1394 jlong sleep_time_ms = | |
1395 (jlong) (elapsed_vtime_sec * _cm->cleanup_sleep_factor() * 1000.0); | |
1396 os::sleep(Thread::current(), sleep_time_ms, false); | |
1397 _start_vtime_sec = end_vtime_sec; | |
1398 } | |
1399 } | |
1400 } | |
1401 | |
1402 return false; | |
1403 } | |
1404 | |
1405 bool changed() { return _changed; } | |
1406 void reset() { _changed = false; _words_done = 0; } | |
1407 void no_yield() { _yield = false; } | |
1408 size_t words_done() { return _words_done; } | |
1409 size_t tot_live() { return _tot_live; } | |
1410 size_t tot_used() { return _tot_used; } | |
1411 }; | |
1412 | |
1413 | |
1414 void ConcurrentMark::calcDesiredRegions() { | |
1415 _region_bm.clear(); | |
1416 _card_bm.clear(); | |
1417 CalcLiveObjectsClosure calccl(false /*final*/, | |
1418 nextMarkBitMap(), this, | |
936 | 1419 &_region_bm, &_card_bm); |
342 | 1420 G1CollectedHeap *g1h = G1CollectedHeap::heap(); |
1421 g1h->heap_region_iterate(&calccl); | |
1422 | |
1423 do { | |
1424 calccl.reset(); | |
1425 g1h->heap_region_iterate(&calccl); | |
1426 } while (calccl.changed()); | |
1427 } | |
1428 | |
1429 class G1ParFinalCountTask: public AbstractGangTask { | |
1430 protected: | |
1431 G1CollectedHeap* _g1h; | |
1432 CMBitMap* _bm; | |
1433 size_t _n_workers; | |
1434 size_t *_live_bytes; | |
1435 size_t *_used_bytes; | |
1436 BitMap* _region_bm; | |
1437 BitMap* _card_bm; | |
1438 public: | |
1439 G1ParFinalCountTask(G1CollectedHeap* g1h, CMBitMap* bm, | |
1440 BitMap* region_bm, BitMap* card_bm) : | |
1441 AbstractGangTask("G1 final counting"), _g1h(g1h), | |
1442 _bm(bm), _region_bm(region_bm), _card_bm(card_bm) | |
1443 { | |
1444 if (ParallelGCThreads > 0) | |
1445 _n_workers = _g1h->workers()->total_workers(); | |
1446 else | |
1447 _n_workers = 1; | |
1448 _live_bytes = NEW_C_HEAP_ARRAY(size_t, _n_workers); | |
1449 _used_bytes = NEW_C_HEAP_ARRAY(size_t, _n_workers); | |
1450 } | |
1451 | |
1452 ~G1ParFinalCountTask() { | |
1453 FREE_C_HEAP_ARRAY(size_t, _live_bytes); | |
1454 FREE_C_HEAP_ARRAY(size_t, _used_bytes); | |
1455 } | |
1456 | |
1457 void work(int i) { | |
1458 CalcLiveObjectsClosure calccl(true /*final*/, | |
1459 _bm, _g1h->concurrent_mark(), | |
936 | 1460 _region_bm, _card_bm); |
342 | 1461 calccl.no_yield(); |
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1462 if (G1CollectedHeap::use_parallel_gc_threads()) { |
355 | 1463 _g1h->heap_region_par_iterate_chunked(&calccl, i, |
1464 HeapRegion::FinalCountClaimValue); | |
342 | 1465 } else { |
1466 _g1h->heap_region_iterate(&calccl); | |
1467 } | |
1468 assert(calccl.complete(), "Shouldn't have yielded!"); | |
1469 | |
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1470 assert((size_t) i < _n_workers, "invariant"); |
342 | 1471 _live_bytes[i] = calccl.tot_live(); |
1472 _used_bytes[i] = calccl.tot_used(); | |
1473 } | |
1474 size_t live_bytes() { | |
1475 size_t live_bytes = 0; | |
1476 for (size_t i = 0; i < _n_workers; ++i) | |
1477 live_bytes += _live_bytes[i]; | |
1478 return live_bytes; | |
1479 } | |
1480 size_t used_bytes() { | |
1481 size_t used_bytes = 0; | |
1482 for (size_t i = 0; i < _n_workers; ++i) | |
1483 used_bytes += _used_bytes[i]; | |
1484 return used_bytes; | |
1485 } | |
1486 }; | |
1487 | |
1488 class G1ParNoteEndTask; | |
1489 | |
1490 class G1NoteEndOfConcMarkClosure : public HeapRegionClosure { | |
1491 G1CollectedHeap* _g1; | |
1492 int _worker_num; | |
1493 size_t _max_live_bytes; | |
1494 size_t _regions_claimed; | |
1495 size_t _freed_bytes; | |
1496 size_t _cleared_h_regions; | |
1497 size_t _freed_regions; | |
1498 UncleanRegionList* _unclean_region_list; | |
1499 double _claimed_region_time; | |
1500 double _max_region_time; | |
1501 | |
1502 public: | |
1503 G1NoteEndOfConcMarkClosure(G1CollectedHeap* g1, | |
1504 UncleanRegionList* list, | |
1505 int worker_num); | |
1506 size_t freed_bytes() { return _freed_bytes; } | |
1507 size_t cleared_h_regions() { return _cleared_h_regions; } | |
1508 size_t freed_regions() { return _freed_regions; } | |
1509 UncleanRegionList* unclean_region_list() { | |
1510 return _unclean_region_list; | |
1511 } | |
1512 | |
1513 bool doHeapRegion(HeapRegion *r); | |
1514 | |
1515 size_t max_live_bytes() { return _max_live_bytes; } | |
1516 size_t regions_claimed() { return _regions_claimed; } | |
1517 double claimed_region_time_sec() { return _claimed_region_time; } | |
1518 double max_region_time_sec() { return _max_region_time; } | |
1519 }; | |
1520 | |
1521 class G1ParNoteEndTask: public AbstractGangTask { | |
1522 friend class G1NoteEndOfConcMarkClosure; | |
1523 protected: | |
1524 G1CollectedHeap* _g1h; | |
1525 size_t _max_live_bytes; | |
1526 size_t _freed_bytes; | |
1527 ConcurrentMark::ParCleanupThreadState** _par_cleanup_thread_state; | |
1528 public: | |
1529 G1ParNoteEndTask(G1CollectedHeap* g1h, | |
1530 ConcurrentMark::ParCleanupThreadState** | |
1531 par_cleanup_thread_state) : | |
1532 AbstractGangTask("G1 note end"), _g1h(g1h), | |
1533 _max_live_bytes(0), _freed_bytes(0), | |
1534 _par_cleanup_thread_state(par_cleanup_thread_state) | |
1535 {} | |
1536 | |
1537 void work(int i) { | |
1538 double start = os::elapsedTime(); | |
1539 G1NoteEndOfConcMarkClosure g1_note_end(_g1h, | |
1540 &_par_cleanup_thread_state[i]->list, | |
1541 i); | |
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1542 if (G1CollectedHeap::use_parallel_gc_threads()) { |
355 | 1543 _g1h->heap_region_par_iterate_chunked(&g1_note_end, i, |
1544 HeapRegion::NoteEndClaimValue); | |
342 | 1545 } else { |
1546 _g1h->heap_region_iterate(&g1_note_end); | |
1547 } | |
1548 assert(g1_note_end.complete(), "Shouldn't have yielded!"); | |
1549 | |
1550 // Now finish up freeing the current thread's regions. | |
1551 _g1h->finish_free_region_work(g1_note_end.freed_bytes(), | |
1552 g1_note_end.cleared_h_regions(), | |
1553 0, NULL); | |
1554 { | |
1555 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); | |
1556 _max_live_bytes += g1_note_end.max_live_bytes(); | |
1557 _freed_bytes += g1_note_end.freed_bytes(); | |
1558 } | |
1559 double end = os::elapsedTime(); | |
1560 if (G1PrintParCleanupStats) { | |
1561 gclog_or_tty->print(" Worker thread %d [%8.3f..%8.3f = %8.3f ms] " | |
1562 "claimed %d regions (tot = %8.3f ms, max = %8.3f ms).\n", | |
1563 i, start, end, (end-start)*1000.0, | |
1564 g1_note_end.regions_claimed(), | |
1565 g1_note_end.claimed_region_time_sec()*1000.0, | |
1566 g1_note_end.max_region_time_sec()*1000.0); | |
1567 } | |
1568 } | |
1569 size_t max_live_bytes() { return _max_live_bytes; } | |
1570 size_t freed_bytes() { return _freed_bytes; } | |
1571 }; | |
1572 | |
1573 class G1ParScrubRemSetTask: public AbstractGangTask { | |
1574 protected: | |
1575 G1RemSet* _g1rs; | |
1576 BitMap* _region_bm; | |
1577 BitMap* _card_bm; | |
1578 public: | |
1579 G1ParScrubRemSetTask(G1CollectedHeap* g1h, | |
1580 BitMap* region_bm, BitMap* card_bm) : | |
1581 AbstractGangTask("G1 ScrubRS"), _g1rs(g1h->g1_rem_set()), | |
1582 _region_bm(region_bm), _card_bm(card_bm) | |
1583 {} | |
1584 | |
1585 void work(int i) { | |
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1586 if (G1CollectedHeap::use_parallel_gc_threads()) { |
355 | 1587 _g1rs->scrub_par(_region_bm, _card_bm, i, |
1588 HeapRegion::ScrubRemSetClaimValue); | |
342 | 1589 } else { |
1590 _g1rs->scrub(_region_bm, _card_bm); | |
1591 } | |
1592 } | |
1593 | |
1594 }; | |
1595 | |
1596 G1NoteEndOfConcMarkClosure:: | |
1597 G1NoteEndOfConcMarkClosure(G1CollectedHeap* g1, | |
1598 UncleanRegionList* list, | |
1599 int worker_num) | |
1600 : _g1(g1), _worker_num(worker_num), | |
1601 _max_live_bytes(0), _regions_claimed(0), | |
1602 _freed_bytes(0), _cleared_h_regions(0), _freed_regions(0), | |
1603 _claimed_region_time(0.0), _max_region_time(0.0), | |
1604 _unclean_region_list(list) | |
1605 {} | |
1606 | |
1607 bool G1NoteEndOfConcMarkClosure::doHeapRegion(HeapRegion *r) { | |
1608 // We use a claim value of zero here because all regions | |
1609 // were claimed with value 1 in the FinalCount task. | |
1610 r->reset_gc_time_stamp(); | |
1611 if (!r->continuesHumongous()) { | |
1612 double start = os::elapsedTime(); | |
1613 _regions_claimed++; | |
1614 r->note_end_of_marking(); | |
1615 _max_live_bytes += r->max_live_bytes(); | |
1616 _g1->free_region_if_totally_empty_work(r, | |
1617 _freed_bytes, | |
1618 _cleared_h_regions, | |
1619 _freed_regions, | |
1620 _unclean_region_list, | |
1621 true /*par*/); | |
1622 double region_time = (os::elapsedTime() - start); | |
1623 _claimed_region_time += region_time; | |
1624 if (region_time > _max_region_time) _max_region_time = region_time; | |
1625 } | |
1626 return false; | |
1627 } | |
1628 | |
1629 void ConcurrentMark::cleanup() { | |
1630 // world is stopped at this checkpoint | |
1631 assert(SafepointSynchronize::is_at_safepoint(), | |
1632 "world should be stopped"); | |
1633 G1CollectedHeap* g1h = G1CollectedHeap::heap(); | |
1634 | |
1635 // If a full collection has happened, we shouldn't do this. | |
1636 if (has_aborted()) { | |
1637 g1h->set_marking_complete(); // So bitmap clearing isn't confused | |
1638 return; | |
1639 } | |
1640 | |
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1641 if (VerifyDuringGC) { |
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1642 HandleMark hm; // handle scope |
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1643 gclog_or_tty->print(" VerifyDuringGC:(before)"); |
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1644 Universe::heap()->prepare_for_verify(); |
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1645 Universe::verify(/* allow dirty */ true, |
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1646 /* silent */ false, |
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1647 /* prev marking */ true); |
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1648 } |
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1649 |
342 | 1650 G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy(); |
1651 g1p->record_concurrent_mark_cleanup_start(); | |
1652 | |
1653 double start = os::elapsedTime(); | |
1654 | |
1655 // Do counting once more with the world stopped for good measure. | |
1656 G1ParFinalCountTask g1_par_count_task(g1h, nextMarkBitMap(), | |
1657 &_region_bm, &_card_bm); | |
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1658 if (G1CollectedHeap::use_parallel_gc_threads()) { |
355 | 1659 assert(g1h->check_heap_region_claim_values( |
1660 HeapRegion::InitialClaimValue), | |
1661 "sanity check"); | |
1662 | |
342 | 1663 int n_workers = g1h->workers()->total_workers(); |
1664 g1h->set_par_threads(n_workers); | |
1665 g1h->workers()->run_task(&g1_par_count_task); | |
1666 g1h->set_par_threads(0); | |
355 | 1667 |
1668 assert(g1h->check_heap_region_claim_values( | |
1669 HeapRegion::FinalCountClaimValue), | |
1670 "sanity check"); | |
342 | 1671 } else { |
1672 g1_par_count_task.work(0); | |
1673 } | |
1674 | |
1675 size_t known_garbage_bytes = | |
1676 g1_par_count_task.used_bytes() - g1_par_count_task.live_bytes(); | |
1677 #if 0 | |
1678 gclog_or_tty->print_cr("used %1.2lf, live %1.2lf, garbage %1.2lf", | |
1679 (double) g1_par_count_task.used_bytes() / (double) (1024 * 1024), | |
1680 (double) g1_par_count_task.live_bytes() / (double) (1024 * 1024), | |
1681 (double) known_garbage_bytes / (double) (1024 * 1024)); | |
1682 #endif // 0 | |
1683 g1p->set_known_garbage_bytes(known_garbage_bytes); | |
1684 | |
1685 size_t start_used_bytes = g1h->used(); | |
1686 _at_least_one_mark_complete = true; | |
1687 g1h->set_marking_complete(); | |
1688 | |
1689 double count_end = os::elapsedTime(); | |
1690 double this_final_counting_time = (count_end - start); | |
1691 if (G1PrintParCleanupStats) { | |
1692 gclog_or_tty->print_cr("Cleanup:"); | |
1693 gclog_or_tty->print_cr(" Finalize counting: %8.3f ms", | |
1694 this_final_counting_time*1000.0); | |
1695 } | |
1696 _total_counting_time += this_final_counting_time; | |
1697 | |
1698 // Install newly created mark bitMap as "prev". | |
1699 swapMarkBitMaps(); | |
1700 | |
1701 g1h->reset_gc_time_stamp(); | |
1702 | |
1703 // Note end of marking in all heap regions. | |
1704 double note_end_start = os::elapsedTime(); | |
1705 G1ParNoteEndTask g1_par_note_end_task(g1h, _par_cleanup_thread_state); | |
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1706 if (G1CollectedHeap::use_parallel_gc_threads()) { |
342 | 1707 int n_workers = g1h->workers()->total_workers(); |
1708 g1h->set_par_threads(n_workers); | |
1709 g1h->workers()->run_task(&g1_par_note_end_task); | |
1710 g1h->set_par_threads(0); | |
355 | 1711 |
1712 assert(g1h->check_heap_region_claim_values(HeapRegion::NoteEndClaimValue), | |
1713 "sanity check"); | |
342 | 1714 } else { |
1715 g1_par_note_end_task.work(0); | |
1716 } | |
1717 g1h->set_unclean_regions_coming(true); | |
1718 double note_end_end = os::elapsedTime(); | |
1719 // Tell the mutators that there might be unclean regions coming... | |
1720 if (G1PrintParCleanupStats) { | |
1721 gclog_or_tty->print_cr(" note end of marking: %8.3f ms.", | |
1722 (note_end_end - note_end_start)*1000.0); | |
1723 } | |
1724 | |
355 | 1725 |
342 | 1726 // call below, since it affects the metric by which we sort the heap |
1727 // regions. | |
1728 if (G1ScrubRemSets) { | |
1729 double rs_scrub_start = os::elapsedTime(); | |
1730 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1h, &_region_bm, &_card_bm); | |
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1731 if (G1CollectedHeap::use_parallel_gc_threads()) { |
342 | 1732 int n_workers = g1h->workers()->total_workers(); |
1733 g1h->set_par_threads(n_workers); | |
1734 g1h->workers()->run_task(&g1_par_scrub_rs_task); | |
1735 g1h->set_par_threads(0); | |
355 | 1736 |
1737 assert(g1h->check_heap_region_claim_values( | |
1738 HeapRegion::ScrubRemSetClaimValue), | |
1739 "sanity check"); | |
342 | 1740 } else { |
1741 g1_par_scrub_rs_task.work(0); | |
1742 } | |
1743 | |
1744 double rs_scrub_end = os::elapsedTime(); | |
1745 double this_rs_scrub_time = (rs_scrub_end - rs_scrub_start); | |
1746 _total_rs_scrub_time += this_rs_scrub_time; | |
1747 } | |
1748 | |
1749 // this will also free any regions totally full of garbage objects, | |
1750 // and sort the regions. | |
1751 g1h->g1_policy()->record_concurrent_mark_cleanup_end( | |
1752 g1_par_note_end_task.freed_bytes(), | |
1753 g1_par_note_end_task.max_live_bytes()); | |
1754 | |
1755 // Statistics. | |
1756 double end = os::elapsedTime(); | |
1757 _cleanup_times.add((end - start) * 1000.0); | |
1758 | |
1759 // G1CollectedHeap::heap()->print(); | |
1760 // gclog_or_tty->print_cr("HEAP GC TIME STAMP : %d", | |
1761 // G1CollectedHeap::heap()->get_gc_time_stamp()); | |
1762 | |
1763 if (PrintGC || PrintGCDetails) { | |
1764 g1h->print_size_transition(gclog_or_tty, | |
1765 start_used_bytes, | |
1766 g1h->used(), | |
1767 g1h->capacity()); | |
1768 } | |
1769 | |
1770 size_t cleaned_up_bytes = start_used_bytes - g1h->used(); | |
1771 g1p->decrease_known_garbage_bytes(cleaned_up_bytes); | |
1772 | |
1773 // We need to make this be a "collection" so any collection pause that | |
1774 // races with it goes around and waits for completeCleanup to finish. | |
1775 g1h->increment_total_collections(); | |
1776 | |
751 | 1777 if (VerifyDuringGC) { |
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1778 HandleMark hm; // handle scope |
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1779 gclog_or_tty->print(" VerifyDuringGC:(after)"); |
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1780 Universe::heap()->prepare_for_verify(); |
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1781 Universe::verify(/* allow dirty */ true, |
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1782 /* silent */ false, |
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1783 /* prev marking */ true); |
342 | 1784 } |
1785 } | |
1786 | |
1787 void ConcurrentMark::completeCleanup() { | |
1788 // A full collection intervened. | |
1789 if (has_aborted()) return; | |
1790 | |
1791 int first = 0; | |
1792 int last = (int)MAX2(ParallelGCThreads, (size_t)1); | |
1793 for (int t = 0; t < last; t++) { | |
1794 UncleanRegionList* list = &_par_cleanup_thread_state[t]->list; | |
1795 assert(list->well_formed(), "Inv"); | |
1796 HeapRegion* hd = list->hd(); | |
1797 while (hd != NULL) { | |
1798 // Now finish up the other stuff. | |
1799 hd->rem_set()->clear(); | |
1800 HeapRegion* next_hd = hd->next_from_unclean_list(); | |
1801 (void)list->pop(); | |
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1802 assert(list->hd() == next_hd, "how not?"); |
342 | 1803 _g1h->put_region_on_unclean_list(hd); |
1804 if (!hd->isHumongous()) { | |
1805 // Add this to the _free_regions count by 1. | |
1806 _g1h->finish_free_region_work(0, 0, 1, NULL); | |
1807 } | |
1808 hd = list->hd(); | |
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1809 assert(hd == next_hd, "how not?"); |
342 | 1810 } |
1811 } | |
1812 } | |
1813 | |
1814 | |
1815 class G1CMIsAliveClosure: public BoolObjectClosure { | |
1816 G1CollectedHeap* _g1; | |
1817 public: | |
1818 G1CMIsAliveClosure(G1CollectedHeap* g1) : | |
1819 _g1(g1) | |
1820 {} | |
1821 | |
1822 void do_object(oop obj) { | |
1823 assert(false, "not to be invoked"); | |
1824 } | |
1825 bool do_object_b(oop obj) { | |
1826 HeapWord* addr = (HeapWord*)obj; | |
1827 return addr != NULL && | |
1828 (!_g1->is_in_g1_reserved(addr) || !_g1->is_obj_ill(obj)); | |
1829 } | |
1830 }; | |
1831 | |
1832 class G1CMKeepAliveClosure: public OopClosure { | |
1833 G1CollectedHeap* _g1; | |
1834 ConcurrentMark* _cm; | |
1835 CMBitMap* _bitMap; | |
1836 public: | |
1837 G1CMKeepAliveClosure(G1CollectedHeap* g1, ConcurrentMark* cm, | |
1838 CMBitMap* bitMap) : | |
1839 _g1(g1), _cm(cm), | |
1840 _bitMap(bitMap) {} | |
1841 | |
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1842 virtual void do_oop(narrowOop* p) { do_oop_work(p); } |
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1843 virtual void do_oop( oop* p) { do_oop_work(p); } |
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1844 |
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1845 template <class T> void do_oop_work(T* p) { |
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1846 oop thisOop = oopDesc::load_decode_heap_oop(p); |
342 | 1847 HeapWord* addr = (HeapWord*)thisOop; |
1848 if (_g1->is_in_g1_reserved(addr) && _g1->is_obj_ill(thisOop)) { | |
1849 _bitMap->mark(addr); | |
1850 _cm->mark_stack_push(thisOop); | |
1851 } | |
1852 } | |
1853 }; | |
1854 | |
1855 class G1CMDrainMarkingStackClosure: public VoidClosure { | |
1856 CMMarkStack* _markStack; | |
1857 CMBitMap* _bitMap; | |
1858 G1CMKeepAliveClosure* _oopClosure; | |
1859 public: | |
1860 G1CMDrainMarkingStackClosure(CMBitMap* bitMap, CMMarkStack* markStack, | |
1861 G1CMKeepAliveClosure* oopClosure) : | |
1862 _bitMap(bitMap), | |
1863 _markStack(markStack), | |
1864 _oopClosure(oopClosure) | |
1865 {} | |
1866 | |
1867 void do_void() { | |
1868 _markStack->drain((OopClosure*)_oopClosure, _bitMap, false); | |
1869 } | |
1870 }; | |
1871 | |
1872 void ConcurrentMark::weakRefsWork(bool clear_all_soft_refs) { | |
1873 ResourceMark rm; | |
1874 HandleMark hm; | |
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1875 G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
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1876 ReferenceProcessor* rp = g1h->ref_processor(); |
342 | 1877 |
1878 // Process weak references. | |
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1879 rp->setup_policy(clear_all_soft_refs); |
342 | 1880 assert(_markStack.isEmpty(), "mark stack should be empty"); |
1881 | |
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1882 G1CMIsAliveClosure g1IsAliveClosure (g1h); |
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1883 G1CMKeepAliveClosure g1KeepAliveClosure(g1h, this, nextMarkBitMap()); |
342 | 1884 G1CMDrainMarkingStackClosure |
1885 g1DrainMarkingStackClosure(nextMarkBitMap(), &_markStack, | |
1886 &g1KeepAliveClosure); | |
1887 | |
1888 // XXXYYY Also: copy the parallel ref processing code from CMS. | |
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1889 rp->process_discovered_references(&g1IsAliveClosure, |
342 | 1890 &g1KeepAliveClosure, |
1891 &g1DrainMarkingStackClosure, | |
1892 NULL); | |
1893 assert(_markStack.overflow() || _markStack.isEmpty(), | |
1894 "mark stack should be empty (unless it overflowed)"); | |
1895 if (_markStack.overflow()) { | |
1896 set_has_overflown(); | |
1897 } | |
1898 | |
1899 rp->enqueue_discovered_references(); | |
1900 rp->verify_no_references_recorded(); | |
1901 assert(!rp->discovery_enabled(), "should have been disabled"); | |
1902 | |
1903 // Now clean up stale oops in SymbolTable and StringTable | |
1904 SymbolTable::unlink(&g1IsAliveClosure); | |
1905 StringTable::unlink(&g1IsAliveClosure); | |
1906 } | |
1907 | |
1908 void ConcurrentMark::swapMarkBitMaps() { | |
1909 CMBitMapRO* temp = _prevMarkBitMap; | |
1910 _prevMarkBitMap = (CMBitMapRO*)_nextMarkBitMap; | |
1911 _nextMarkBitMap = (CMBitMap*) temp; | |
1912 } | |
1913 | |
1914 class CMRemarkTask: public AbstractGangTask { | |
1915 private: | |
1916 ConcurrentMark *_cm; | |
1917 | |
1918 public: | |
1919 void work(int worker_i) { | |
1920 // Since all available tasks are actually started, we should | |
1921 // only proceed if we're supposed to be actived. | |
1922 if ((size_t)worker_i < _cm->active_tasks()) { | |
1923 CMTask* task = _cm->task(worker_i); | |
1924 task->record_start_time(); | |
1925 do { | |
1926 task->do_marking_step(1000000000.0 /* something very large */); | |
1927 } while (task->has_aborted() && !_cm->has_overflown()); | |
1928 // If we overflow, then we do not want to restart. We instead | |
1929 // want to abort remark and do concurrent marking again. | |
1930 task->record_end_time(); | |
1931 } | |
1932 } | |
1933 | |
1934 CMRemarkTask(ConcurrentMark* cm) : | |
1935 AbstractGangTask("Par Remark"), _cm(cm) { } | |
1936 }; | |
1937 | |
1938 void ConcurrentMark::checkpointRootsFinalWork() { | |
1939 ResourceMark rm; | |
1940 HandleMark hm; | |
1941 G1CollectedHeap* g1h = G1CollectedHeap::heap(); | |
1942 | |
1943 g1h->ensure_parsability(false); | |
1944 | |
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1945 if (G1CollectedHeap::use_parallel_gc_threads()) { |
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1946 G1CollectedHeap::StrongRootsScope srs(g1h); |
342 | 1947 // this is remark, so we'll use up all available threads |
1948 int active_workers = ParallelGCThreads; | |
1949 set_phase(active_workers, false); | |
1950 | |
1951 CMRemarkTask remarkTask(this); | |
1952 // We will start all available threads, even if we decide that the | |
1953 // active_workers will be fewer. The extra ones will just bail out | |
1954 // immediately. | |
1955 int n_workers = g1h->workers()->total_workers(); | |
1956 g1h->set_par_threads(n_workers); | |
1957 g1h->workers()->run_task(&remarkTask); | |
1958 g1h->set_par_threads(0); | |
1959 } else { | |
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1960 G1CollectedHeap::StrongRootsScope srs(g1h); |
342 | 1961 // this is remark, so we'll use up all available threads |
1962 int active_workers = 1; | |
1963 set_phase(active_workers, false); | |
1964 | |
1965 CMRemarkTask remarkTask(this); | |
1966 // We will start all available threads, even if we decide that the | |
1967 // active_workers will be fewer. The extra ones will just bail out | |
1968 // immediately. | |
1969 remarkTask.work(0); | |
1970 } | |
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1971 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set(); |
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1972 guarantee(satb_mq_set.completed_buffers_num() == 0, "invariant"); |
342 | 1973 |
1974 print_stats(); | |
1975 | |
1976 if (!restart_for_overflow()) | |
1977 set_non_marking_state(); | |
1978 | |
1979 #if VERIFY_OBJS_PROCESSED | |
1980 if (_scan_obj_cl.objs_processed != ThreadLocalObjQueue::objs_enqueued) { | |
1981 gclog_or_tty->print_cr("Processed = %d, enqueued = %d.", | |
1982 _scan_obj_cl.objs_processed, | |
1983 ThreadLocalObjQueue::objs_enqueued); | |
1984 guarantee(_scan_obj_cl.objs_processed == | |
1985 ThreadLocalObjQueue::objs_enqueued, | |
1986 "Different number of objs processed and enqueued."); | |
1987 } | |
1988 #endif | |
1989 } | |
1990 | |
1044 | 1991 #ifndef PRODUCT |
1992 | |
1388 | 1993 class PrintReachableOopClosure: public OopClosure { |
342 | 1994 private: |
1995 G1CollectedHeap* _g1h; | |
1996 CMBitMapRO* _bitmap; | |
1997 outputStream* _out; | |
1044 | 1998 bool _use_prev_marking; |
1388 | 1999 bool _all; |
342 | 2000 |
2001 public: | |
1388 | 2002 PrintReachableOopClosure(CMBitMapRO* bitmap, |
2003 outputStream* out, | |
2004 bool use_prev_marking, | |
2005 bool all) : | |
1044 | 2006 _g1h(G1CollectedHeap::heap()), |
1388 | 2007 _bitmap(bitmap), _out(out), _use_prev_marking(use_prev_marking), _all(all) { } |
342 | 2008 |
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2009 void do_oop(narrowOop* p) { do_oop_work(p); } |
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2010 void do_oop( oop* p) { do_oop_work(p); } |
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2011 |
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2012 template <class T> void do_oop_work(T* p) { |
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2013 oop obj = oopDesc::load_decode_heap_oop(p); |
342 | 2014 const char* str = NULL; |
2015 const char* str2 = ""; | |
2016 | |
1388 | 2017 if (obj == NULL) { |
2018 str = ""; | |
2019 } else if (!_g1h->is_in_g1_reserved(obj)) { | |
2020 str = " O"; | |
2021 } else { | |
342 | 2022 HeapRegion* hr = _g1h->heap_region_containing(obj); |
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2023 guarantee(hr != NULL, "invariant"); |
1044 | 2024 bool over_tams = false; |
2025 if (_use_prev_marking) { | |
2026 over_tams = hr->obj_allocated_since_prev_marking(obj); | |
2027 } else { | |
2028 over_tams = hr->obj_allocated_since_next_marking(obj); | |
2029 } | |
1388 | 2030 bool marked = _bitmap->isMarked((HeapWord*) obj); |
1044 | 2031 |
2032 if (over_tams) { | |
1388 | 2033 str = " >"; |
2034 if (marked) { | |
342 | 2035 str2 = " AND MARKED"; |
1044 | 2036 } |
1388 | 2037 } else if (marked) { |
2038 str = " M"; | |
1044 | 2039 } else { |
1388 | 2040 str = " NOT"; |
1044 | 2041 } |
342 | 2042 } |
2043 | |
1388 | 2044 _out->print_cr(" "PTR_FORMAT": "PTR_FORMAT"%s%s", |
342 | 2045 p, (void*) obj, str, str2); |
2046 } | |
2047 }; | |
2048 | |
1388 | 2049 class PrintReachableObjectClosure : public ObjectClosure { |
342 | 2050 private: |
1044 | 2051 CMBitMapRO* _bitmap; |
342 | 2052 outputStream* _out; |
1044 | 2053 bool _use_prev_marking; |
1388 | 2054 bool _all; |
2055 HeapRegion* _hr; | |
342 | 2056 |
2057 public: | |
1388 | 2058 PrintReachableObjectClosure(CMBitMapRO* bitmap, |
2059 outputStream* out, | |
2060 bool use_prev_marking, | |
2061 bool all, | |
2062 HeapRegion* hr) : | |
2063 _bitmap(bitmap), _out(out), | |
2064 _use_prev_marking(use_prev_marking), _all(all), _hr(hr) { } | |
2065 | |
2066 void do_object(oop o) { | |
2067 bool over_tams; | |
2068 if (_use_prev_marking) { | |
2069 over_tams = _hr->obj_allocated_since_prev_marking(o); | |
2070 } else { | |
2071 over_tams = _hr->obj_allocated_since_next_marking(o); | |
2072 } | |
2073 bool marked = _bitmap->isMarked((HeapWord*) o); | |
2074 bool print_it = _all || over_tams || marked; | |
2075 | |
2076 if (print_it) { | |
2077 _out->print_cr(" "PTR_FORMAT"%s", | |
2078 o, (over_tams) ? " >" : (marked) ? " M" : ""); | |
2079 PrintReachableOopClosure oopCl(_bitmap, _out, _use_prev_marking, _all); | |
2080 o->oop_iterate(&oopCl); | |
2081 } | |
342 | 2082 } |
2083 }; | |
2084 | |
1388 | 2085 class PrintReachableRegionClosure : public HeapRegionClosure { |
342 | 2086 private: |
1044 | 2087 CMBitMapRO* _bitmap; |
342 | 2088 outputStream* _out; |
1044 | 2089 bool _use_prev_marking; |
1388 | 2090 bool _all; |
342 | 2091 |
2092 public: | |
2093 bool doHeapRegion(HeapRegion* hr) { | |
2094 HeapWord* b = hr->bottom(); | |
2095 HeapWord* e = hr->end(); | |
2096 HeapWord* t = hr->top(); | |
1044 | 2097 HeapWord* p = NULL; |
2098 if (_use_prev_marking) { | |
2099 p = hr->prev_top_at_mark_start(); | |
2100 } else { | |
2101 p = hr->next_top_at_mark_start(); | |
2102 } | |
342 | 2103 _out->print_cr("** ["PTR_FORMAT", "PTR_FORMAT"] top: "PTR_FORMAT" " |
1044 | 2104 "TAMS: "PTR_FORMAT, b, e, t, p); |
1388 | 2105 _out->cr(); |
2106 | |
2107 HeapWord* from = b; | |
2108 HeapWord* to = t; | |
2109 | |
2110 if (to > from) { | |
2111 _out->print_cr("Objects in ["PTR_FORMAT", "PTR_FORMAT"]", from, to); | |
2112 _out->cr(); | |
2113 PrintReachableObjectClosure ocl(_bitmap, _out, | |
2114 _use_prev_marking, _all, hr); | |
2115 hr->object_iterate_mem_careful(MemRegion(from, to), &ocl); | |
2116 _out->cr(); | |
2117 } | |
342 | 2118 |
2119 return false; | |
2120 } | |
2121 | |
1388 | 2122 PrintReachableRegionClosure(CMBitMapRO* bitmap, |
2123 outputStream* out, | |
2124 bool use_prev_marking, | |
2125 bool all) : | |
2126 _bitmap(bitmap), _out(out), _use_prev_marking(use_prev_marking), _all(all) { } | |
342 | 2127 }; |
2128 | |
1388 | 2129 void ConcurrentMark::print_reachable(const char* str, |
2130 bool use_prev_marking, | |
2131 bool all) { | |
2132 gclog_or_tty->cr(); | |
2133 gclog_or_tty->print_cr("== Doing heap dump... "); | |
1044 | 2134 |
2135 if (G1PrintReachableBaseFile == NULL) { | |
2136 gclog_or_tty->print_cr(" #### error: no base file defined"); | |
2137 return; | |
2138 } | |
2139 | |
2140 if (strlen(G1PrintReachableBaseFile) + 1 + strlen(str) > | |
2141 (JVM_MAXPATHLEN - 1)) { | |
2142 gclog_or_tty->print_cr(" #### error: file name too long"); | |
2143 return; | |
2144 } | |
2145 | |
2146 char file_name[JVM_MAXPATHLEN]; | |
2147 sprintf(file_name, "%s.%s", G1PrintReachableBaseFile, str); | |
2148 gclog_or_tty->print_cr(" dumping to file %s", file_name); | |
2149 | |
2150 fileStream fout(file_name); | |
2151 if (!fout.is_open()) { | |
2152 gclog_or_tty->print_cr(" #### error: could not open file"); | |
2153 return; | |
2154 } | |
2155 | |
2156 outputStream* out = &fout; | |
2157 | |
2158 CMBitMapRO* bitmap = NULL; | |
2159 if (use_prev_marking) { | |
2160 bitmap = _prevMarkBitMap; | |
2161 } else { | |
2162 bitmap = _nextMarkBitMap; | |
2163 } | |
2164 | |
2165 out->print_cr("-- USING %s", (use_prev_marking) ? "PTAMS" : "NTAMS"); | |
2166 out->cr(); | |
2167 | |
1388 | 2168 out->print_cr("--- ITERATING OVER REGIONS"); |
1044 | 2169 out->cr(); |
1388 | 2170 PrintReachableRegionClosure rcl(bitmap, out, use_prev_marking, all); |
2171 _g1h->heap_region_iterate(&rcl); | |
1044 | 2172 out->cr(); |
2173 | |
2174 gclog_or_tty->print_cr(" done"); | |
1388 | 2175 gclog_or_tty->flush(); |
342 | 2176 } |
2177 | |
1044 | 2178 #endif // PRODUCT |
2179 | |
342 | 2180 // This note is for drainAllSATBBuffers and the code in between. |
2181 // In the future we could reuse a task to do this work during an | |
2182 // evacuation pause (since now tasks are not active and can be claimed | |
2183 // during an evacuation pause). This was a late change to the code and | |
2184 // is currently not being taken advantage of. | |
2185 | |
2186 class CMGlobalObjectClosure : public ObjectClosure { | |
2187 private: | |
2188 ConcurrentMark* _cm; | |
2189 | |
2190 public: | |
2191 void do_object(oop obj) { | |
2192 _cm->deal_with_reference(obj); | |
2193 } | |
2194 | |
2195 CMGlobalObjectClosure(ConcurrentMark* cm) : _cm(cm) { } | |
2196 }; | |
2197 | |
2198 void ConcurrentMark::deal_with_reference(oop obj) { | |
2199 if (verbose_high()) | |
2200 gclog_or_tty->print_cr("[global] we're dealing with reference "PTR_FORMAT, | |
2201 (void*) obj); | |
2202 | |
2203 | |
2204 HeapWord* objAddr = (HeapWord*) obj; | |
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2205 assert(obj->is_oop_or_null(true /* ignore mark word */), "Error"); |
342 | 2206 if (_g1h->is_in_g1_reserved(objAddr)) { |
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2207 assert(obj != NULL, "is_in_g1_reserved should ensure this"); |
342 | 2208 HeapRegion* hr = _g1h->heap_region_containing(obj); |
2209 if (_g1h->is_obj_ill(obj, hr)) { | |
2210 if (verbose_high()) | |
2211 gclog_or_tty->print_cr("[global] "PTR_FORMAT" is not considered " | |
2212 "marked", (void*) obj); | |
2213 | |
2214 // we need to mark it first | |
2215 if (_nextMarkBitMap->parMark(objAddr)) { | |
2216 // No OrderAccess:store_load() is needed. It is implicit in the | |
2217 // CAS done in parMark(objAddr) above | |
2218 HeapWord* finger = _finger; | |
2219 if (objAddr < finger) { | |
2220 if (verbose_high()) | |
2221 gclog_or_tty->print_cr("[global] below the global finger " | |
2222 "("PTR_FORMAT"), pushing it", finger); | |
2223 if (!mark_stack_push(obj)) { | |
2224 if (verbose_low()) | |
2225 gclog_or_tty->print_cr("[global] global stack overflow during " | |
2226 "deal_with_reference"); | |
2227 } | |
2228 } | |
2229 } | |
2230 } | |
2231 } | |
2232 } | |
2233 | |
2234 void ConcurrentMark::drainAllSATBBuffers() { | |
2235 CMGlobalObjectClosure oc(this); | |
2236 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set(); | |
2237 satb_mq_set.set_closure(&oc); | |
2238 | |
2239 while (satb_mq_set.apply_closure_to_completed_buffer()) { | |
2240 if (verbose_medium()) | |
2241 gclog_or_tty->print_cr("[global] processed an SATB buffer"); | |
2242 } | |
2243 | |
2244 // no need to check whether we should do this, as this is only | |
2245 // called during an evacuation pause | |
2246 satb_mq_set.iterate_closure_all_threads(); | |
2247 | |
2248 satb_mq_set.set_closure(NULL); | |
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2249 assert(satb_mq_set.completed_buffers_num() == 0, "invariant"); |
342 | 2250 } |
2251 | |
2252 void ConcurrentMark::markPrev(oop p) { | |
2253 // Note we are overriding the read-only view of the prev map here, via | |
2254 // the cast. | |
2255 ((CMBitMap*)_prevMarkBitMap)->mark((HeapWord*)p); | |
2256 } | |
2257 | |
2258 void ConcurrentMark::clear(oop p) { | |
2259 assert(p != NULL && p->is_oop(), "expected an oop"); | |
2260 HeapWord* addr = (HeapWord*)p; | |
2261 assert(addr >= _nextMarkBitMap->startWord() || | |
2262 addr < _nextMarkBitMap->endWord(), "in a region"); | |
2263 | |
2264 _nextMarkBitMap->clear(addr); | |
2265 } | |
2266 | |
2267 void ConcurrentMark::clearRangeBothMaps(MemRegion mr) { | |
2268 // Note we are overriding the read-only view of the prev map here, via | |
2269 // the cast. | |
2270 ((CMBitMap*)_prevMarkBitMap)->clearRange(mr); | |
2271 _nextMarkBitMap->clearRange(mr); | |
2272 } | |
2273 | |
2274 HeapRegion* | |
2275 ConcurrentMark::claim_region(int task_num) { | |
2276 // "checkpoint" the finger | |
2277 HeapWord* finger = _finger; | |
2278 | |
2279 // _heap_end will not change underneath our feet; it only changes at | |
2280 // yield points. | |
2281 while (finger < _heap_end) { | |
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2282 assert(_g1h->is_in_g1_reserved(finger), "invariant"); |
342 | 2283 |
2284 // is the gap between reading the finger and doing the CAS too long? | |
2285 | |
2286 HeapRegion* curr_region = _g1h->heap_region_containing(finger); | |
2287 HeapWord* bottom = curr_region->bottom(); | |
2288 HeapWord* end = curr_region->end(); | |
2289 HeapWord* limit = curr_region->next_top_at_mark_start(); | |
2290 | |
2291 if (verbose_low()) | |
2292 gclog_or_tty->print_cr("[%d] curr_region = "PTR_FORMAT" " | |
2293 "["PTR_FORMAT", "PTR_FORMAT"), " | |
2294 "limit = "PTR_FORMAT, | |
2295 task_num, curr_region, bottom, end, limit); | |
2296 | |
2297 HeapWord* res = | |
2298 (HeapWord*) Atomic::cmpxchg_ptr(end, &_finger, finger); | |
2299 if (res == finger) { | |
2300 // we succeeded | |
2301 | |
2302 // notice that _finger == end cannot be guaranteed here since, | |
2303 // someone else might have moved the finger even further | |
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2304 assert(_finger >= end, "the finger should have moved forward"); |
342 | 2305 |
2306 if (verbose_low()) | |
2307 gclog_or_tty->print_cr("[%d] we were successful with region = " | |
2308 PTR_FORMAT, task_num, curr_region); | |
2309 | |
2310 if (limit > bottom) { | |
2311 if (verbose_low()) | |
2312 gclog_or_tty->print_cr("[%d] region "PTR_FORMAT" is not empty, " | |
2313 "returning it ", task_num, curr_region); | |
2314 return curr_region; | |
2315 } else { | |
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2316 assert(limit == bottom, |
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2317 "the region limit should be at bottom"); |
342 | 2318 if (verbose_low()) |
2319 gclog_or_tty->print_cr("[%d] region "PTR_FORMAT" is empty, " | |
2320 "returning NULL", task_num, curr_region); | |
2321 // we return NULL and the caller should try calling | |
2322 // claim_region() again. | |
2323 return NULL; | |
2324 } | |
2325 } else { | |
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2326 assert(_finger > finger, "the finger should have moved forward"); |
342 | 2327 if (verbose_low()) |
2328 gclog_or_tty->print_cr("[%d] somebody else moved the finger, " | |
2329 "global finger = "PTR_FORMAT", " | |
2330 "our finger = "PTR_FORMAT, | |
2331 task_num, _finger, finger); | |
2332 | |
2333 // read it again | |
2334 finger = _finger; | |
2335 } | |
2336 } | |
2337 | |
2338 return NULL; | |
2339 } | |
2340 | |
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2341 bool ConcurrentMark::invalidate_aborted_regions_in_cset() { |
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2342 bool result = false; |
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2343 for (int i = 0; i < (int)_max_task_num; ++i) { |
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2344 CMTask* the_task = _tasks[i]; |
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2345 MemRegion mr = the_task->aborted_region(); |
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2346 if (mr.start() != NULL) { |
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2347 assert(mr.end() != NULL, "invariant"); |
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2348 assert(mr.word_size() > 0, "invariant"); |
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2349 HeapRegion* hr = _g1h->heap_region_containing(mr.start()); |
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2350 assert(hr != NULL, "invariant"); |
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2351 if (hr->in_collection_set()) { |
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2352 // The region points into the collection set |
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2353 the_task->set_aborted_region(MemRegion()); |
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2354 result = true; |
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2355 } |
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2356 } |
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2357 } |
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2358 return result; |
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2359 } |
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2360 |
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2361 bool ConcurrentMark::has_aborted_regions() { |
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2362 for (int i = 0; i < (int)_max_task_num; ++i) { |
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2363 CMTask* the_task = _tasks[i]; |
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2364 MemRegion mr = the_task->aborted_region(); |
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2365 if (mr.start() != NULL) { |
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2366 assert(mr.end() != NULL, "invariant"); |
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2367 assert(mr.word_size() > 0, "invariant"); |
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2368 return true; |
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2369 } |
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2370 } |
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2371 return false; |
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2372 } |
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2373 |
342 | 2374 void ConcurrentMark::oops_do(OopClosure* cl) { |
2375 if (_markStack.size() > 0 && verbose_low()) | |
2376 gclog_or_tty->print_cr("[global] scanning the global marking stack, " | |
2377 "size = %d", _markStack.size()); | |
2378 // we first iterate over the contents of the mark stack... | |
2379 _markStack.oops_do(cl); | |
2380 | |
2381 for (int i = 0; i < (int)_max_task_num; ++i) { | |
2382 OopTaskQueue* queue = _task_queues->queue((int)i); | |
2383 | |
2384 if (queue->size() > 0 && verbose_low()) | |
2385 gclog_or_tty->print_cr("[global] scanning task queue of task %d, " | |
2386 "size = %d", i, queue->size()); | |
2387 | |
2388 // ...then over the contents of the all the task queues. | |
2389 queue->oops_do(cl); | |
2390 } | |
2391 | |
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2392 // Invalidate any entries, that are in the region stack, that |
342 | 2393 // point into the collection set |
2394 if (_regionStack.invalidate_entries_into_cset()) { | |
2395 // otherwise, any gray objects copied during the evacuation pause | |
2396 // might not be visited. | |
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2397 assert(_should_gray_objects, "invariant"); |
342 | 2398 } |
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2399 |
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2400 // Invalidate any aborted regions, recorded in the individual CM |
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2401 // tasks, that point into the collection set. |
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2402 if (invalidate_aborted_regions_in_cset()) { |
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2403 // otherwise, any gray objects copied during the evacuation pause |
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2404 // might not be visited. |
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2405 assert(_should_gray_objects, "invariant"); |
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2406 } |
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2407 |
342 | 2408 } |
2409 | |
2410 void ConcurrentMark::clear_marking_state() { | |
2411 _markStack.setEmpty(); | |
2412 _markStack.clear_overflow(); | |
2413 _regionStack.setEmpty(); | |
2414 _regionStack.clear_overflow(); | |
2415 clear_has_overflown(); | |
2416 _finger = _heap_start; | |
2417 | |
2418 for (int i = 0; i < (int)_max_task_num; ++i) { | |
2419 OopTaskQueue* queue = _task_queues->queue(i); | |
2420 queue->set_empty(); | |
2421 } | |
2422 } | |
2423 | |
2424 void ConcurrentMark::print_stats() { | |
2425 if (verbose_stats()) { | |
2426 gclog_or_tty->print_cr("---------------------------------------------------------------------"); | |
2427 for (size_t i = 0; i < _active_tasks; ++i) { | |
2428 _tasks[i]->print_stats(); | |
2429 gclog_or_tty->print_cr("---------------------------------------------------------------------"); | |
2430 } | |
2431 } | |
2432 } | |
2433 | |
2434 class CSMarkOopClosure: public OopClosure { | |
2435 friend class CSMarkBitMapClosure; | |
2436 | |
2437 G1CollectedHeap* _g1h; | |
2438 CMBitMap* _bm; | |
2439 ConcurrentMark* _cm; | |
2440 oop* _ms; | |
2441 jint* _array_ind_stack; | |
2442 int _ms_size; | |
2443 int _ms_ind; | |
2444 int _array_increment; | |
2445 | |
2446 bool push(oop obj, int arr_ind = 0) { | |
2447 if (_ms_ind == _ms_size) { | |
2448 gclog_or_tty->print_cr("Mark stack is full."); | |
2449 return false; | |
2450 } | |
2451 _ms[_ms_ind] = obj; | |
2452 if (obj->is_objArray()) _array_ind_stack[_ms_ind] = arr_ind; | |
2453 _ms_ind++; | |
2454 return true; | |
2455 } | |
2456 | |
2457 oop pop() { | |
2458 if (_ms_ind == 0) return NULL; | |
2459 else { | |
2460 _ms_ind--; | |
2461 return _ms[_ms_ind]; | |
2462 } | |
2463 } | |
2464 | |
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2465 template <class T> bool drain() { |
342 | 2466 while (_ms_ind > 0) { |
2467 oop obj = pop(); | |
2468 assert(obj != NULL, "Since index was non-zero."); | |
2469 if (obj->is_objArray()) { | |
2470 jint arr_ind = _array_ind_stack[_ms_ind]; | |
2471 objArrayOop aobj = objArrayOop(obj); | |
2472 jint len = aobj->length(); | |
2473 jint next_arr_ind = arr_ind + _array_increment; | |
2474 if (next_arr_ind < len) { | |
2475 push(obj, next_arr_ind); | |
2476 } | |
2477 // Now process this portion of this one. | |
2478 int lim = MIN2(next_arr_ind, len); | |
2479 for (int j = arr_ind; j < lim; j++) { | |
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2480 do_oop(aobj->objArrayOopDesc::obj_at_addr<T>(j)); |
342 | 2481 } |
2482 | |
2483 } else { | |
2484 obj->oop_iterate(this); | |
2485 } | |
2486 if (abort()) return false; | |
2487 } | |
2488 return true; | |
2489 } | |
2490 | |
2491 public: | |
2492 CSMarkOopClosure(ConcurrentMark* cm, int ms_size) : | |
2493 _g1h(G1CollectedHeap::heap()), | |
2494 _cm(cm), | |
2495 _bm(cm->nextMarkBitMap()), | |
2496 _ms_size(ms_size), _ms_ind(0), | |
2497 _ms(NEW_C_HEAP_ARRAY(oop, ms_size)), | |
2498 _array_ind_stack(NEW_C_HEAP_ARRAY(jint, ms_size)), | |
2499 _array_increment(MAX2(ms_size/8, 16)) | |
2500 {} | |
2501 | |
2502 ~CSMarkOopClosure() { | |
2503 FREE_C_HEAP_ARRAY(oop, _ms); | |
2504 FREE_C_HEAP_ARRAY(jint, _array_ind_stack); | |
2505 } | |
2506 | |
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2507 virtual void do_oop(narrowOop* p) { do_oop_work(p); } |
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2508 virtual void do_oop( oop* p) { do_oop_work(p); } |
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2509 |
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2510 template <class T> void do_oop_work(T* p) { |
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2511 T heap_oop = oopDesc::load_heap_oop(p); |
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2512 if (oopDesc::is_null(heap_oop)) return; |
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2513 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); |
342 | 2514 if (obj->is_forwarded()) { |
2515 // If the object has already been forwarded, we have to make sure | |
2516 // that it's marked. So follow the forwarding pointer. Note that | |
2517 // this does the right thing for self-forwarding pointers in the | |
2518 // evacuation failure case. | |
2519 obj = obj->forwardee(); | |
2520 } | |
2521 HeapRegion* hr = _g1h->heap_region_containing(obj); | |
2522 if (hr != NULL) { | |
2523 if (hr->in_collection_set()) { | |
2524 if (_g1h->is_obj_ill(obj)) { | |
2525 _bm->mark((HeapWord*)obj); | |
2526 if (!push(obj)) { | |
2527 gclog_or_tty->print_cr("Setting abort in CSMarkOopClosure because push failed."); | |
2528 set_abort(); | |
2529 } | |
2530 } | |
2531 } else { | |
2532 // Outside the collection set; we need to gray it | |
2533 _cm->deal_with_reference(obj); | |
2534 } | |
2535 } | |
2536 } | |
2537 }; | |
2538 | |
2539 class CSMarkBitMapClosure: public BitMapClosure { | |
2540 G1CollectedHeap* _g1h; | |
2541 CMBitMap* _bitMap; | |
2542 ConcurrentMark* _cm; | |
2543 CSMarkOopClosure _oop_cl; | |
2544 public: | |
2545 CSMarkBitMapClosure(ConcurrentMark* cm, int ms_size) : | |
2546 _g1h(G1CollectedHeap::heap()), | |
2547 _bitMap(cm->nextMarkBitMap()), | |
2548 _oop_cl(cm, ms_size) | |
2549 {} | |
2550 | |
2551 ~CSMarkBitMapClosure() {} | |
2552 | |
2553 bool do_bit(size_t offset) { | |
2554 // convert offset into a HeapWord* | |
2555 HeapWord* addr = _bitMap->offsetToHeapWord(offset); | |
2556 assert(_bitMap->endWord() && addr < _bitMap->endWord(), | |
2557 "address out of range"); | |
2558 assert(_bitMap->isMarked(addr), "tautology"); | |
2559 oop obj = oop(addr); | |
2560 if (!obj->is_forwarded()) { | |
2561 if (!_oop_cl.push(obj)) return false; | |
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2562 if (UseCompressedOops) { |
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2563 if (!_oop_cl.drain<narrowOop>()) return false; |
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2564 } else { |
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2565 if (!_oop_cl.drain<oop>()) return false; |
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2566 } |
342 | 2567 } |
2568 // Otherwise... | |
2569 return true; | |
2570 } | |
2571 }; | |
2572 | |
2573 | |
2574 class CompleteMarkingInCSHRClosure: public HeapRegionClosure { | |
2575 CMBitMap* _bm; | |
2576 CSMarkBitMapClosure _bit_cl; | |
2577 enum SomePrivateConstants { | |
2578 MSSize = 1000 | |
2579 }; | |
2580 bool _completed; | |
2581 public: | |
2582 CompleteMarkingInCSHRClosure(ConcurrentMark* cm) : | |
2583 _bm(cm->nextMarkBitMap()), | |
2584 _bit_cl(cm, MSSize), | |
2585 _completed(true) | |
2586 {} | |
2587 | |
2588 ~CompleteMarkingInCSHRClosure() {} | |
2589 | |
2590 bool doHeapRegion(HeapRegion* r) { | |
2591 if (!r->evacuation_failed()) { | |
2592 MemRegion mr = MemRegion(r->bottom(), r->next_top_at_mark_start()); | |
2593 if (!mr.is_empty()) { | |
2594 if (!_bm->iterate(&_bit_cl, mr)) { | |
2595 _completed = false; | |
2596 return true; | |
2597 } | |
2598 } | |
2599 } | |
2600 return false; | |
2601 } | |
2602 | |
2603 bool completed() { return _completed; } | |
2604 }; | |
2605 | |
2606 class ClearMarksInHRClosure: public HeapRegionClosure { | |
2607 CMBitMap* _bm; | |
2608 public: | |
2609 ClearMarksInHRClosure(CMBitMap* bm): _bm(bm) { } | |
2610 | |
2611 bool doHeapRegion(HeapRegion* r) { | |
2612 if (!r->used_region().is_empty() && !r->evacuation_failed()) { | |
2613 MemRegion usedMR = r->used_region(); | |
2614 _bm->clearRange(r->used_region()); | |
2615 } | |
2616 return false; | |
2617 } | |
2618 }; | |
2619 | |
2620 void ConcurrentMark::complete_marking_in_collection_set() { | |
2621 G1CollectedHeap* g1h = G1CollectedHeap::heap(); | |
2622 | |
2623 if (!g1h->mark_in_progress()) { | |
2624 g1h->g1_policy()->record_mark_closure_time(0.0); | |
2625 return; | |
2626 } | |
2627 | |
2628 int i = 1; | |
2629 double start = os::elapsedTime(); | |
2630 while (true) { | |
2631 i++; | |
2632 CompleteMarkingInCSHRClosure cmplt(this); | |
2633 g1h->collection_set_iterate(&cmplt); | |
2634 if (cmplt.completed()) break; | |
2635 } | |
2636 double end_time = os::elapsedTime(); | |
2637 double elapsed_time_ms = (end_time - start) * 1000.0; | |
2638 g1h->g1_policy()->record_mark_closure_time(elapsed_time_ms); | |
2639 | |
2640 ClearMarksInHRClosure clr(nextMarkBitMap()); | |
2641 g1h->collection_set_iterate(&clr); | |
2642 } | |
2643 | |
2644 // The next two methods deal with the following optimisation. Some | |
2645 // objects are gray by being marked and located above the finger. If | |
2646 // they are copied, during an evacuation pause, below the finger then | |
2647 // the need to be pushed on the stack. The observation is that, if | |
2648 // there are no regions in the collection set located above the | |
2649 // finger, then the above cannot happen, hence we do not need to | |
2650 // explicitly gray any objects when copying them to below the | |
2651 // finger. The global stack will be scanned to ensure that, if it | |
2652 // points to objects being copied, it will update their | |
2653 // location. There is a tricky situation with the gray objects in | |
2654 // region stack that are being coped, however. See the comment in | |
2655 // newCSet(). | |
2656 | |
2657 void ConcurrentMark::newCSet() { | |
2658 if (!concurrent_marking_in_progress()) | |
2659 // nothing to do if marking is not in progress | |
2660 return; | |
2661 | |
2662 // find what the lowest finger is among the global and local fingers | |
2663 _min_finger = _finger; | |
2664 for (int i = 0; i < (int)_max_task_num; ++i) { | |
2665 CMTask* task = _tasks[i]; | |
2666 HeapWord* task_finger = task->finger(); | |
2667 if (task_finger != NULL && task_finger < _min_finger) | |
2668 _min_finger = task_finger; | |
2669 } | |
2670 | |
2671 _should_gray_objects = false; | |
2672 | |
2673 // This fixes a very subtle and fustrating bug. It might be the case | |
2674 // that, during en evacuation pause, heap regions that contain | |
2675 // objects that are gray (by being in regions contained in the | |
2676 // region stack) are included in the collection set. Since such gray | |
2677 // objects will be moved, and because it's not easy to redirect | |
2678 // region stack entries to point to a new location (because objects | |
2679 // in one region might be scattered to multiple regions after they | |
2680 // are copied), one option is to ensure that all marked objects | |
2681 // copied during a pause are pushed on the stack. Notice, however, | |
2682 // that this problem can only happen when the region stack is not | |
2683 // empty during an evacuation pause. So, we make the fix a bit less | |
2684 // conservative and ensure that regions are pushed on the stack, | |
2685 // irrespective whether all collection set regions are below the | |
2686 // finger, if the region stack is not empty. This is expected to be | |
2687 // a rare case, so I don't think it's necessary to be smarted about it. | |
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2688 if (!region_stack_empty() || has_aborted_regions()) |
342 | 2689 _should_gray_objects = true; |
2690 } | |
2691 | |
2692 void ConcurrentMark::registerCSetRegion(HeapRegion* hr) { | |
2693 if (!concurrent_marking_in_progress()) | |
2694 return; | |
2695 | |
2696 HeapWord* region_end = hr->end(); | |
2697 if (region_end > _min_finger) | |
2698 _should_gray_objects = true; | |
2699 } | |
2700 | |
2701 // abandon current marking iteration due to a Full GC | |
2702 void ConcurrentMark::abort() { | |
2703 // Clear all marks to force marking thread to do nothing | |
2704 _nextMarkBitMap->clearAll(); | |
2705 // Empty mark stack | |
2706 clear_marking_state(); | |
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2707 for (int i = 0; i < (int)_max_task_num; ++i) { |
342 | 2708 _tasks[i]->clear_region_fields(); |
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2709 _tasks[i]->clear_aborted_region(); |
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2710 } |
342 | 2711 _has_aborted = true; |
2712 | |
2713 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set(); | |
2714 satb_mq_set.abandon_partial_marking(); | |
1317
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2715 // This can be called either during or outside marking, we'll read |
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2716 // the expected_active value from the SATB queue set. |
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2717 satb_mq_set.set_active_all_threads( |
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2718 false, /* new active value */ |
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2719 satb_mq_set.is_active() /* expected_active */); |
342 | 2720 } |
2721 | |
2722 static void print_ms_time_info(const char* prefix, const char* name, | |
2723 NumberSeq& ns) { | |
2724 gclog_or_tty->print_cr("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).", | |
2725 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg()); | |
2726 if (ns.num() > 0) { | |
2727 gclog_or_tty->print_cr("%s [std. dev = %8.2f ms, max = %8.2f ms]", | |
2728 prefix, ns.sd(), ns.maximum()); | |
2729 } | |
2730 } | |
2731 | |
2732 void ConcurrentMark::print_summary_info() { | |
2733 gclog_or_tty->print_cr(" Concurrent marking:"); | |
2734 print_ms_time_info(" ", "init marks", _init_times); | |
2735 print_ms_time_info(" ", "remarks", _remark_times); | |
2736 { | |
2737 print_ms_time_info(" ", "final marks", _remark_mark_times); | |
2738 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times); | |
2739 | |
2740 } | |
2741 print_ms_time_info(" ", "cleanups", _cleanup_times); | |
2742 gclog_or_tty->print_cr(" Final counting total time = %8.2f s (avg = %8.2f ms).", | |
2743 _total_counting_time, | |
2744 (_cleanup_times.num() > 0 ? _total_counting_time * 1000.0 / | |
2745 (double)_cleanup_times.num() | |
2746 : 0.0)); | |
2747 if (G1ScrubRemSets) { | |
2748 gclog_or_tty->print_cr(" RS scrub total time = %8.2f s (avg = %8.2f ms).", | |
2749 _total_rs_scrub_time, | |
2750 (_cleanup_times.num() > 0 ? _total_rs_scrub_time * 1000.0 / | |
2751 (double)_cleanup_times.num() | |
2752 : 0.0)); | |
2753 } | |
2754 gclog_or_tty->print_cr(" Total stop_world time = %8.2f s.", | |
2755 (_init_times.sum() + _remark_times.sum() + | |
2756 _cleanup_times.sum())/1000.0); | |
2757 gclog_or_tty->print_cr(" Total concurrent time = %8.2f s " | |
2758 "(%8.2f s marking, %8.2f s counting).", | |
2759 cmThread()->vtime_accum(), | |
2760 cmThread()->vtime_mark_accum(), | |
2761 cmThread()->vtime_count_accum()); | |
2762 } | |
2763 | |
1019 | 2764 void ConcurrentMark::print_worker_threads_on(outputStream* st) const { |
2765 _parallel_workers->print_worker_threads_on(st); | |
2766 } | |
2767 | |
342 | 2768 // Closures |
2769 // XXX: there seems to be a lot of code duplication here; | |
2770 // should refactor and consolidate the shared code. | |
2771 | |
2772 // This closure is used to mark refs into the CMS generation in | |
2773 // the CMS bit map. Called at the first checkpoint. | |
2774 | |
2775 // We take a break if someone is trying to stop the world. | |
2776 bool ConcurrentMark::do_yield_check(int worker_i) { | |
2777 if (should_yield()) { | |
2778 if (worker_i == 0) | |
2779 _g1h->g1_policy()->record_concurrent_pause(); | |
2780 cmThread()->yield(); | |
2781 if (worker_i == 0) | |
2782 _g1h->g1_policy()->record_concurrent_pause_end(); | |
2783 return true; | |
2784 } else { | |
2785 return false; | |
2786 } | |
2787 } | |
2788 | |
2789 bool ConcurrentMark::should_yield() { | |
2790 return cmThread()->should_yield(); | |
2791 } | |
2792 | |
2793 bool ConcurrentMark::containing_card_is_marked(void* p) { | |
2794 size_t offset = pointer_delta(p, _g1h->reserved_region().start(), 1); | |
2795 return _card_bm.at(offset >> CardTableModRefBS::card_shift); | |
2796 } | |
2797 | |
2798 bool ConcurrentMark::containing_cards_are_marked(void* start, | |
2799 void* last) { | |
2800 return | |
2801 containing_card_is_marked(start) && | |
2802 containing_card_is_marked(last); | |
2803 } | |
2804 | |
2805 #ifndef PRODUCT | |
2806 // for debugging purposes | |
2807 void ConcurrentMark::print_finger() { | |
2808 gclog_or_tty->print_cr("heap ["PTR_FORMAT", "PTR_FORMAT"), global finger = "PTR_FORMAT, | |
2809 _heap_start, _heap_end, _finger); | |
2810 for (int i = 0; i < (int) _max_task_num; ++i) { | |
2811 gclog_or_tty->print(" %d: "PTR_FORMAT, i, _tasks[i]->finger()); | |
2812 } | |
2813 gclog_or_tty->print_cr(""); | |
2814 } | |
2815 #endif | |
2816 | |
2817 // Closure for iteration over bitmaps | |
2818 class CMBitMapClosure : public BitMapClosure { | |
2819 private: | |
2820 // the bitmap that is being iterated over | |
2821 CMBitMap* _nextMarkBitMap; | |
2822 ConcurrentMark* _cm; | |
2823 CMTask* _task; | |
2824 // true if we're scanning a heap region claimed by the task (so that | |
2825 // we move the finger along), false if we're not, i.e. currently when | |
2826 // scanning a heap region popped from the region stack (so that we | |
2827 // do not move the task finger along; it'd be a mistake if we did so). | |
2828 bool _scanning_heap_region; | |
2829 | |
2830 public: | |
2831 CMBitMapClosure(CMTask *task, | |
2832 ConcurrentMark* cm, | |
2833 CMBitMap* nextMarkBitMap) | |
2834 : _task(task), _cm(cm), _nextMarkBitMap(nextMarkBitMap) { } | |
2835 | |
2836 void set_scanning_heap_region(bool scanning_heap_region) { | |
2837 _scanning_heap_region = scanning_heap_region; | |
2838 } | |
2839 | |
2840 bool do_bit(size_t offset) { | |
2841 HeapWord* addr = _nextMarkBitMap->offsetToHeapWord(offset); | |
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2842 assert(_nextMarkBitMap->isMarked(addr), "invariant"); |
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2843 assert( addr < _cm->finger(), "invariant"); |
342 | 2844 |
2845 if (_scanning_heap_region) { | |
2846 statsOnly( _task->increase_objs_found_on_bitmap() ); | |
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2847 assert(addr >= _task->finger(), "invariant"); |
342 | 2848 // We move that task's local finger along. |
2849 _task->move_finger_to(addr); | |
2850 } else { | |
2851 // We move the task's region finger along. | |
2852 _task->move_region_finger_to(addr); | |
2853 } | |
2854 | |
2855 _task->scan_object(oop(addr)); | |
2856 // we only partially drain the local queue and global stack | |
2857 _task->drain_local_queue(true); | |
2858 _task->drain_global_stack(true); | |
2859 | |
2860 // if the has_aborted flag has been raised, we need to bail out of | |
2861 // the iteration | |
2862 return !_task->has_aborted(); | |
2863 } | |
2864 }; | |
2865 | |
2866 // Closure for iterating over objects, currently only used for | |
2867 // processing SATB buffers. | |
2868 class CMObjectClosure : public ObjectClosure { | |
2869 private: | |
2870 CMTask* _task; | |
2871 | |
2872 public: | |
2873 void do_object(oop obj) { | |
2874 _task->deal_with_reference(obj); | |
2875 } | |
2876 | |
2877 CMObjectClosure(CMTask* task) : _task(task) { } | |
2878 }; | |
2879 | |
2880 // Closure for iterating over object fields | |
2881 class CMOopClosure : public OopClosure { | |
2882 private: | |
2883 G1CollectedHeap* _g1h; | |
2884 ConcurrentMark* _cm; | |
2885 CMTask* _task; | |
2886 | |
2887 public: | |
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2888 virtual void do_oop(narrowOop* p) { do_oop_work(p); } |
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2889 virtual void do_oop( oop* p) { do_oop_work(p); } |
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2890 |
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2891 template <class T> void do_oop_work(T* p) { |
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2892 assert(_g1h->is_in_g1_reserved((HeapWord*) p), "invariant"); |
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2893 assert(!_g1h->heap_region_containing((HeapWord*) p)->is_on_free_list(), |
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2894 "invariant"); |
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2895 |
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2896 oop obj = oopDesc::load_decode_heap_oop(p); |
342 | 2897 if (_cm->verbose_high()) |
2898 gclog_or_tty->print_cr("[%d] we're looking at location " | |
2899 "*"PTR_FORMAT" = "PTR_FORMAT, | |
2900 _task->task_id(), p, (void*) obj); | |
2901 _task->deal_with_reference(obj); | |
2902 } | |
2903 | |
2904 CMOopClosure(G1CollectedHeap* g1h, | |
2905 ConcurrentMark* cm, | |
2906 CMTask* task) | |
2907 : _g1h(g1h), _cm(cm), _task(task) { } | |
2908 }; | |
2909 | |
2910 void CMTask::setup_for_region(HeapRegion* hr) { | |
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2911 // Separated the asserts so that we know which one fires. |
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2912 assert(hr != NULL, |
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2913 "claim_region() should have filtered out continues humongous regions"); |
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2914 assert(!hr->continuesHumongous(), |
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2915 "claim_region() should have filtered out continues humongous regions"); |
342 | 2916 |
2917 if (_cm->verbose_low()) | |
2918 gclog_or_tty->print_cr("[%d] setting up for region "PTR_FORMAT, | |
2919 _task_id, hr); | |
2920 | |
2921 _curr_region = hr; | |
2922 _finger = hr->bottom(); | |
2923 update_region_limit(); | |
2924 } | |
2925 | |
2926 void CMTask::update_region_limit() { | |
2927 HeapRegion* hr = _curr_region; | |
2928 HeapWord* bottom = hr->bottom(); | |
2929 HeapWord* limit = hr->next_top_at_mark_start(); | |
2930 | |
2931 if (limit == bottom) { | |
2932 if (_cm->verbose_low()) | |
2933 gclog_or_tty->print_cr("[%d] found an empty region " | |
2934 "["PTR_FORMAT", "PTR_FORMAT")", | |
2935 _task_id, bottom, limit); | |
2936 // The region was collected underneath our feet. | |
2937 // We set the finger to bottom to ensure that the bitmap | |
2938 // iteration that will follow this will not do anything. | |
2939 // (this is not a condition that holds when we set the region up, | |
2940 // as the region is not supposed to be empty in the first place) | |
2941 _finger = bottom; | |
2942 } else if (limit >= _region_limit) { | |
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2943 assert(limit >= _finger, "peace of mind"); |
342 | 2944 } else { |
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2945 assert(limit < _region_limit, "only way to get here"); |
342 | 2946 // This can happen under some pretty unusual circumstances. An |
2947 // evacuation pause empties the region underneath our feet (NTAMS | |
2948 // at bottom). We then do some allocation in the region (NTAMS | |
2949 // stays at bottom), followed by the region being used as a GC | |
2950 // alloc region (NTAMS will move to top() and the objects | |
2951 // originally below it will be grayed). All objects now marked in | |
2952 // the region are explicitly grayed, if below the global finger, | |
2953 // and we do not need in fact to scan anything else. So, we simply | |
2954 // set _finger to be limit to ensure that the bitmap iteration | |
2955 // doesn't do anything. | |
2956 _finger = limit; | |
2957 } | |
2958 | |
2959 _region_limit = limit; | |
2960 } | |
2961 | |
2962 void CMTask::giveup_current_region() { | |
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2963 assert(_curr_region != NULL, "invariant"); |
342 | 2964 if (_cm->verbose_low()) |
2965 gclog_or_tty->print_cr("[%d] giving up region "PTR_FORMAT, | |
2966 _task_id, _curr_region); | |
2967 clear_region_fields(); | |
2968 } | |
2969 | |
2970 void CMTask::clear_region_fields() { | |
2971 // Values for these three fields that indicate that we're not | |
2972 // holding on to a region. | |
2973 _curr_region = NULL; | |
2974 _finger = NULL; | |
2975 _region_limit = NULL; | |
2976 | |
2977 _region_finger = NULL; | |
2978 } | |
2979 | |
2980 void CMTask::reset(CMBitMap* nextMarkBitMap) { | |
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2981 guarantee(nextMarkBitMap != NULL, "invariant"); |
342 | 2982 |
2983 if (_cm->verbose_low()) | |
2984 gclog_or_tty->print_cr("[%d] resetting", _task_id); | |
2985 | |
2986 _nextMarkBitMap = nextMarkBitMap; | |
2987 clear_region_fields(); | |
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2988 clear_aborted_region(); |
342 | 2989 |
2990 _calls = 0; | |
2991 _elapsed_time_ms = 0.0; | |
2992 _termination_time_ms = 0.0; | |
2993 _termination_start_time_ms = 0.0; | |
2994 | |
2995 #if _MARKING_STATS_ | |
2996 _local_pushes = 0; | |
2997 _local_pops = 0; | |
2998 _local_max_size = 0; | |
2999 _objs_scanned = 0; | |
3000 _global_pushes = 0; | |
3001 _global_pops = 0; | |
3002 _global_max_size = 0; | |
3003 _global_transfers_to = 0; | |
3004 _global_transfers_from = 0; | |
3005 _region_stack_pops = 0; | |
3006 _regions_claimed = 0; | |
3007 _objs_found_on_bitmap = 0; | |
3008 _satb_buffers_processed = 0; | |
3009 _steal_attempts = 0; | |
3010 _steals = 0; | |
3011 _aborted = 0; | |
3012 _aborted_overflow = 0; | |
3013 _aborted_cm_aborted = 0; | |
3014 _aborted_yield = 0; | |
3015 _aborted_timed_out = 0; | |
3016 _aborted_satb = 0; | |
3017 _aborted_termination = 0; | |
3018 #endif // _MARKING_STATS_ | |
3019 } | |
3020 | |
3021 bool CMTask::should_exit_termination() { | |
3022 regular_clock_call(); | |
3023 // This is called when we are in the termination protocol. We should | |
3024 // quit if, for some reason, this task wants to abort or the global | |
3025 // stack is not empty (this means that we can get work from it). | |
3026 return !_cm->mark_stack_empty() || has_aborted(); | |
3027 } | |
3028 | |
3029 // This determines whether the method below will check both the local | |
3030 // and global fingers when determining whether to push on the stack a | |
3031 // gray object (value 1) or whether it will only check the global one | |
3032 // (value 0). The tradeoffs are that the former will be a bit more | |
3033 // accurate and possibly push less on the stack, but it might also be | |
3034 // a little bit slower. | |
3035 | |
3036 #define _CHECK_BOTH_FINGERS_ 1 | |
3037 | |
3038 void CMTask::deal_with_reference(oop obj) { | |
3039 if (_cm->verbose_high()) | |
3040 gclog_or_tty->print_cr("[%d] we're dealing with reference = "PTR_FORMAT, | |
3041 _task_id, (void*) obj); | |
3042 | |
3043 ++_refs_reached; | |
3044 | |
3045 HeapWord* objAddr = (HeapWord*) obj; | |
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3046 assert(obj->is_oop_or_null(true /* ignore mark word */), "Error"); |
342 | 3047 if (_g1h->is_in_g1_reserved(objAddr)) { |
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3048 assert(obj != NULL, "is_in_g1_reserved should ensure this"); |
342 | 3049 HeapRegion* hr = _g1h->heap_region_containing(obj); |
3050 if (_g1h->is_obj_ill(obj, hr)) { | |
3051 if (_cm->verbose_high()) | |
3052 gclog_or_tty->print_cr("[%d] "PTR_FORMAT" is not considered marked", | |
3053 _task_id, (void*) obj); | |
3054 | |
3055 // we need to mark it first | |
3056 if (_nextMarkBitMap->parMark(objAddr)) { | |
3057 // No OrderAccess:store_load() is needed. It is implicit in the | |
3058 // CAS done in parMark(objAddr) above | |
3059 HeapWord* global_finger = _cm->finger(); | |
3060 | |
3061 #if _CHECK_BOTH_FINGERS_ | |
3062 // we will check both the local and global fingers | |
3063 | |
3064 if (_finger != NULL && objAddr < _finger) { | |
3065 if (_cm->verbose_high()) | |
3066 gclog_or_tty->print_cr("[%d] below the local finger ("PTR_FORMAT"), " | |
3067 "pushing it", _task_id, _finger); | |
3068 push(obj); | |
3069 } else if (_curr_region != NULL && objAddr < _region_limit) { | |
3070 // do nothing | |
3071 } else if (objAddr < global_finger) { | |
3072 // Notice that the global finger might be moving forward | |
3073 // concurrently. This is not a problem. In the worst case, we | |
3074 // mark the object while it is above the global finger and, by | |
3075 // the time we read the global finger, it has moved forward | |
3076 // passed this object. In this case, the object will probably | |
3077 // be visited when a task is scanning the region and will also | |
3078 // be pushed on the stack. So, some duplicate work, but no | |
3079 // correctness problems. | |
3080 | |
3081 if (_cm->verbose_high()) | |
3082 gclog_or_tty->print_cr("[%d] below the global finger " | |
3083 "("PTR_FORMAT"), pushing it", | |
3084 _task_id, global_finger); | |
3085 push(obj); | |
3086 } else { | |
3087 // do nothing | |
3088 } | |
3089 #else // _CHECK_BOTH_FINGERS_ | |
3090 // we will only check the global finger | |
3091 | |
3092 if (objAddr < global_finger) { | |
3093 // see long comment above | |
3094 | |
3095 if (_cm->verbose_high()) | |
3096 gclog_or_tty->print_cr("[%d] below the global finger " | |
3097 "("PTR_FORMAT"), pushing it", | |
3098 _task_id, global_finger); | |
3099 push(obj); | |
3100 } | |
3101 #endif // _CHECK_BOTH_FINGERS_ | |
3102 } | |
3103 } | |
3104 } | |
3105 } | |
3106 | |
3107 void CMTask::push(oop obj) { | |
3108 HeapWord* objAddr = (HeapWord*) obj; | |
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3109 assert(_g1h->is_in_g1_reserved(objAddr), "invariant"); |
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3110 assert(!_g1h->heap_region_containing(objAddr)->is_on_free_list(), |
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3111 "invariant"); |
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3112 assert(!_g1h->is_obj_ill(obj), "invariant"); |
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3113 assert(_nextMarkBitMap->isMarked(objAddr), "invariant"); |
342 | 3114 |
3115 if (_cm->verbose_high()) | |
3116 gclog_or_tty->print_cr("[%d] pushing "PTR_FORMAT, _task_id, (void*) obj); | |
3117 | |
3118 if (!_task_queue->push(obj)) { | |
3119 // The local task queue looks full. We need to push some entries | |
3120 // to the global stack. | |
3121 | |
3122 if (_cm->verbose_medium()) | |
3123 gclog_or_tty->print_cr("[%d] task queue overflow, " | |
3124 "moving entries to the global stack", | |
3125 _task_id); | |
3126 move_entries_to_global_stack(); | |
3127 | |
3128 // this should succeed since, even if we overflow the global | |
3129 // stack, we should have definitely removed some entries from the | |
3130 // local queue. So, there must be space on it. | |
3131 bool success = _task_queue->push(obj); | |
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3132 assert(success, "invariant"); |
342 | 3133 } |
3134 | |
3135 statsOnly( int tmp_size = _task_queue->size(); | |
3136 if (tmp_size > _local_max_size) | |
3137 _local_max_size = tmp_size; | |
3138 ++_local_pushes ); | |
3139 } | |
3140 | |
3141 void CMTask::reached_limit() { | |
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3142 assert(_words_scanned >= _words_scanned_limit || |
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3143 _refs_reached >= _refs_reached_limit , |
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3144 "shouldn't have been called otherwise"); |
342 | 3145 regular_clock_call(); |
3146 } | |
3147 | |
3148 void CMTask::regular_clock_call() { | |
3149 if (has_aborted()) | |
3150 return; | |
3151 | |
3152 // First, we need to recalculate the words scanned and refs reached | |
3153 // limits for the next clock call. | |
3154 recalculate_limits(); | |
3155 | |
3156 // During the regular clock call we do the following | |
3157 | |
3158 // (1) If an overflow has been flagged, then we abort. | |
3159 if (_cm->has_overflown()) { | |
3160 set_has_aborted(); | |
3161 return; | |
3162 } | |
3163 | |
3164 // If we are not concurrent (i.e. we're doing remark) we don't need | |
3165 // to check anything else. The other steps are only needed during | |
3166 // the concurrent marking phase. | |
3167 if (!concurrent()) | |
3168 return; | |
3169 | |
3170 // (2) If marking has been aborted for Full GC, then we also abort. | |
3171 if (_cm->has_aborted()) { | |
3172 set_has_aborted(); | |
3173 statsOnly( ++_aborted_cm_aborted ); | |
3174 return; | |
3175 } | |
3176 | |
3177 double curr_time_ms = os::elapsedVTime() * 1000.0; | |
3178 | |
3179 // (3) If marking stats are enabled, then we update the step history. | |
3180 #if _MARKING_STATS_ | |
3181 if (_words_scanned >= _words_scanned_limit) | |
3182 ++_clock_due_to_scanning; | |
3183 if (_refs_reached >= _refs_reached_limit) | |
3184 ++_clock_due_to_marking; | |
3185 | |
3186 double last_interval_ms = curr_time_ms - _interval_start_time_ms; | |
3187 _interval_start_time_ms = curr_time_ms; | |
3188 _all_clock_intervals_ms.add(last_interval_ms); | |
3189 | |
3190 if (_cm->verbose_medium()) { | |
3191 gclog_or_tty->print_cr("[%d] regular clock, interval = %1.2lfms, " | |
3192 "scanned = %d%s, refs reached = %d%s", | |
3193 _task_id, last_interval_ms, | |
3194 _words_scanned, | |
3195 (_words_scanned >= _words_scanned_limit) ? " (*)" : "", | |
3196 _refs_reached, | |
3197 (_refs_reached >= _refs_reached_limit) ? " (*)" : ""); | |
3198 } | |
3199 #endif // _MARKING_STATS_ | |
3200 | |
3201 // (4) We check whether we should yield. If we have to, then we abort. | |
3202 if (_cm->should_yield()) { | |
3203 // We should yield. To do this we abort the task. The caller is | |
3204 // responsible for yielding. | |
3205 set_has_aborted(); | |
3206 statsOnly( ++_aborted_yield ); | |
3207 return; | |
3208 } | |
3209 | |
3210 // (5) We check whether we've reached our time quota. If we have, | |
3211 // then we abort. | |
3212 double elapsed_time_ms = curr_time_ms - _start_time_ms; | |
3213 if (elapsed_time_ms > _time_target_ms) { | |
3214 set_has_aborted(); | |
3215 _has_aborted_timed_out = true; | |
3216 statsOnly( ++_aborted_timed_out ); | |
3217 return; | |
3218 } | |
3219 | |
3220 // (6) Finally, we check whether there are enough completed STAB | |
3221 // buffers available for processing. If there are, we abort. | |
3222 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set(); | |
3223 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) { | |
3224 if (_cm->verbose_low()) | |
3225 gclog_or_tty->print_cr("[%d] aborting to deal with pending SATB buffers", | |
3226 _task_id); | |
3227 // we do need to process SATB buffers, we'll abort and restart | |
3228 // the marking task to do so | |
3229 set_has_aborted(); | |
3230 statsOnly( ++_aborted_satb ); | |
3231 return; | |
3232 } | |
3233 } | |
3234 | |
3235 void CMTask::recalculate_limits() { | |
3236 _real_words_scanned_limit = _words_scanned + words_scanned_period; | |
3237 _words_scanned_limit = _real_words_scanned_limit; | |
3238 | |
3239 _real_refs_reached_limit = _refs_reached + refs_reached_period; | |
3240 _refs_reached_limit = _real_refs_reached_limit; | |
3241 } | |
3242 | |
3243 void CMTask::decrease_limits() { | |
3244 // This is called when we believe that we're going to do an infrequent | |
3245 // operation which will increase the per byte scanned cost (i.e. move | |
3246 // entries to/from the global stack). It basically tries to decrease the | |
3247 // scanning limit so that the clock is called earlier. | |
3248 | |
3249 if (_cm->verbose_medium()) | |
3250 gclog_or_tty->print_cr("[%d] decreasing limits", _task_id); | |
3251 | |
3252 _words_scanned_limit = _real_words_scanned_limit - | |
3253 3 * words_scanned_period / 4; | |
3254 _refs_reached_limit = _real_refs_reached_limit - | |
3255 3 * refs_reached_period / 4; | |
3256 } | |
3257 | |
3258 void CMTask::move_entries_to_global_stack() { | |
3259 // local array where we'll store the entries that will be popped | |
3260 // from the local queue | |
3261 oop buffer[global_stack_transfer_size]; | |
3262 | |
3263 int n = 0; | |
3264 oop obj; | |
3265 while (n < global_stack_transfer_size && _task_queue->pop_local(obj)) { | |
3266 buffer[n] = obj; | |
3267 ++n; | |
3268 } | |
3269 | |
3270 if (n > 0) { | |
3271 // we popped at least one entry from the local queue | |
3272 | |
3273 statsOnly( ++_global_transfers_to; _local_pops += n ); | |
3274 | |
3275 if (!_cm->mark_stack_push(buffer, n)) { | |
3276 if (_cm->verbose_low()) | |
3277 gclog_or_tty->print_cr("[%d] aborting due to global stack overflow", _task_id); | |
3278 set_has_aborted(); | |
3279 } else { | |
3280 // the transfer was successful | |
3281 | |
3282 if (_cm->verbose_medium()) | |
3283 gclog_or_tty->print_cr("[%d] pushed %d entries to the global stack", | |
3284 _task_id, n); | |
3285 statsOnly( int tmp_size = _cm->mark_stack_size(); | |
3286 if (tmp_size > _global_max_size) | |
3287 _global_max_size = tmp_size; | |
3288 _global_pushes += n ); | |
3289 } | |
3290 } | |
3291 | |
3292 // this operation was quite expensive, so decrease the limits | |
3293 decrease_limits(); | |
3294 } | |
3295 | |
3296 void CMTask::get_entries_from_global_stack() { | |
3297 // local array where we'll store the entries that will be popped | |
3298 // from the global stack. | |
3299 oop buffer[global_stack_transfer_size]; | |
3300 int n; | |
3301 _cm->mark_stack_pop(buffer, global_stack_transfer_size, &n); | |
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3302 assert(n <= global_stack_transfer_size, |
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3303 "we should not pop more than the given limit"); |
342 | 3304 if (n > 0) { |
3305 // yes, we did actually pop at least one entry | |
3306 | |
3307 statsOnly( ++_global_transfers_from; _global_pops += n ); | |
3308 if (_cm->verbose_medium()) | |
3309 gclog_or_tty->print_cr("[%d] popped %d entries from the global stack", | |
3310 _task_id, n); | |
3311 for (int i = 0; i < n; ++i) { | |
3312 bool success = _task_queue->push(buffer[i]); | |
3313 // We only call this when the local queue is empty or under a | |
3314 // given target limit. So, we do not expect this push to fail. | |
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3315 assert(success, "invariant"); |
342 | 3316 } |
3317 | |
3318 statsOnly( int tmp_size = _task_queue->size(); | |
3319 if (tmp_size > _local_max_size) | |
3320 _local_max_size = tmp_size; | |
3321 _local_pushes += n ); | |
3322 } | |
3323 | |
3324 // this operation was quite expensive, so decrease the limits | |
3325 decrease_limits(); | |
3326 } | |
3327 | |
3328 void CMTask::drain_local_queue(bool partially) { | |
3329 if (has_aborted()) | |
3330 return; | |
3331 | |
3332 // Decide what the target size is, depending whether we're going to | |
3333 // drain it partially (so that other tasks can steal if they run out | |
3334 // of things to do) or totally (at the very end). | |
3335 size_t target_size; | |
3336 if (partially) | |
3337 target_size = MIN2((size_t)_task_queue->max_elems()/3, GCDrainStackTargetSize); | |
3338 else | |
3339 target_size = 0; | |
3340 | |
3341 if (_task_queue->size() > target_size) { | |
3342 if (_cm->verbose_high()) | |
3343 gclog_or_tty->print_cr("[%d] draining local queue, target size = %d", | |
3344 _task_id, target_size); | |
3345 | |
3346 oop obj; | |
3347 bool ret = _task_queue->pop_local(obj); | |
3348 while (ret) { | |
3349 statsOnly( ++_local_pops ); | |
3350 | |
3351 if (_cm->verbose_high()) | |
3352 gclog_or_tty->print_cr("[%d] popped "PTR_FORMAT, _task_id, | |
3353 (void*) obj); | |
3354 | |
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3355 assert(_g1h->is_in_g1_reserved((HeapWord*) obj), "invariant" ); |
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3356 assert(!_g1h->heap_region_containing(obj)->is_on_free_list(), |
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3357 "invariant"); |
342 | 3358 |
3359 scan_object(obj); | |
3360 | |
3361 if (_task_queue->size() <= target_size || has_aborted()) | |
3362 ret = false; | |
3363 else | |
3364 ret = _task_queue->pop_local(obj); | |
3365 } | |
3366 | |
3367 if (_cm->verbose_high()) | |
3368 gclog_or_tty->print_cr("[%d] drained local queue, size = %d", | |
3369 _task_id, _task_queue->size()); | |
3370 } | |
3371 } | |
3372 | |
3373 void CMTask::drain_global_stack(bool partially) { | |
3374 if (has_aborted()) | |
3375 return; | |
3376 | |
3377 // We have a policy to drain the local queue before we attempt to | |
3378 // drain the global stack. | |
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3379 assert(partially || _task_queue->size() == 0, "invariant"); |
342 | 3380 |
3381 // Decide what the target size is, depending whether we're going to | |
3382 // drain it partially (so that other tasks can steal if they run out | |
3383 // of things to do) or totally (at the very end). Notice that, | |
3384 // because we move entries from the global stack in chunks or | |
3385 // because another task might be doing the same, we might in fact | |
3386 // drop below the target. But, this is not a problem. | |
3387 size_t target_size; | |
3388 if (partially) | |
3389 target_size = _cm->partial_mark_stack_size_target(); | |
3390 else | |
3391 target_size = 0; | |
3392 | |
3393 if (_cm->mark_stack_size() > target_size) { | |
3394 if (_cm->verbose_low()) | |
3395 gclog_or_tty->print_cr("[%d] draining global_stack, target size %d", | |
3396 _task_id, target_size); | |
3397 | |
3398 while (!has_aborted() && _cm->mark_stack_size() > target_size) { | |
3399 get_entries_from_global_stack(); | |
3400 drain_local_queue(partially); | |
3401 } | |
3402 | |
3403 if (_cm->verbose_low()) | |
3404 gclog_or_tty->print_cr("[%d] drained global stack, size = %d", | |
3405 _task_id, _cm->mark_stack_size()); | |
3406 } | |
3407 } | |
3408 | |
3409 // SATB Queue has several assumptions on whether to call the par or | |
3410 // non-par versions of the methods. this is why some of the code is | |
3411 // replicated. We should really get rid of the single-threaded version | |
3412 // of the code to simplify things. | |
3413 void CMTask::drain_satb_buffers() { | |
3414 if (has_aborted()) | |
3415 return; | |
3416 | |
3417 // We set this so that the regular clock knows that we're in the | |
3418 // middle of draining buffers and doesn't set the abort flag when it | |
3419 // notices that SATB buffers are available for draining. It'd be | |
3420 // very counter productive if it did that. :-) | |
3421 _draining_satb_buffers = true; | |
3422 | |
3423 CMObjectClosure oc(this); | |
3424 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set(); | |
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3425 if (G1CollectedHeap::use_parallel_gc_threads()) |
342 | 3426 satb_mq_set.set_par_closure(_task_id, &oc); |
3427 else | |
3428 satb_mq_set.set_closure(&oc); | |
3429 | |
3430 // This keeps claiming and applying the closure to completed buffers | |
3431 // until we run out of buffers or we need to abort. | |
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3432 if (G1CollectedHeap::use_parallel_gc_threads()) { |
342 | 3433 while (!has_aborted() && |
3434 satb_mq_set.par_apply_closure_to_completed_buffer(_task_id)) { | |
3435 if (_cm->verbose_medium()) | |
3436 gclog_or_tty->print_cr("[%d] processed an SATB buffer", _task_id); | |
3437 statsOnly( ++_satb_buffers_processed ); | |
3438 regular_clock_call(); | |
3439 } | |
3440 } else { | |
3441 while (!has_aborted() && | |
3442 satb_mq_set.apply_closure_to_completed_buffer()) { | |
3443 if (_cm->verbose_medium()) | |
3444 gclog_or_tty->print_cr("[%d] processed an SATB buffer", _task_id); | |
3445 statsOnly( ++_satb_buffers_processed ); | |
3446 regular_clock_call(); | |
3447 } | |
3448 } | |
3449 | |
3450 if (!concurrent() && !has_aborted()) { | |
3451 // We should only do this during remark. | |
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3452 if (G1CollectedHeap::use_parallel_gc_threads()) |
342 | 3453 satb_mq_set.par_iterate_closure_all_threads(_task_id); |
3454 else | |
3455 satb_mq_set.iterate_closure_all_threads(); | |
3456 } | |
3457 | |
3458 _draining_satb_buffers = false; | |
3459 | |
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3460 assert(has_aborted() || |
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3461 concurrent() || |
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3462 satb_mq_set.completed_buffers_num() == 0, "invariant"); |
342 | 3463 |
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3464 if (G1CollectedHeap::use_parallel_gc_threads()) |
342 | 3465 satb_mq_set.set_par_closure(_task_id, NULL); |
3466 else | |
3467 satb_mq_set.set_closure(NULL); | |
3468 | |
3469 // again, this was a potentially expensive operation, decrease the | |
3470 // limits to get the regular clock call early | |
3471 decrease_limits(); | |
3472 } | |
3473 | |
3474 void CMTask::drain_region_stack(BitMapClosure* bc) { | |
3475 if (has_aborted()) | |
3476 return; | |
3477 | |
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3478 assert(_region_finger == NULL, |
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3479 "it should be NULL when we're not scanning a region"); |
342 | 3480 |
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3481 if (!_cm->region_stack_empty() || !_aborted_region.is_empty()) { |
342 | 3482 if (_cm->verbose_low()) |
3483 gclog_or_tty->print_cr("[%d] draining region stack, size = %d", | |
3484 _task_id, _cm->region_stack_size()); | |
3485 | |
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3486 MemRegion mr; |
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3487 |
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3488 if (!_aborted_region.is_empty()) { |
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3489 mr = _aborted_region; |
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3490 _aborted_region = MemRegion(); |
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3491 |
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3492 if (_cm->verbose_low()) |
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3493 gclog_or_tty->print_cr("[%d] scanning aborted region [ " PTR_FORMAT ", " PTR_FORMAT " )", |
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3494 _task_id, mr.start(), mr.end()); |
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3495 } else { |
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3496 mr = _cm->region_stack_pop_lock_free(); |
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3497 // it returns MemRegion() if the pop fails |
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3498 statsOnly(if (mr.start() != NULL) ++_region_stack_pops ); |
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3499 } |
342 | 3500 |
3501 while (mr.start() != NULL) { | |
3502 if (_cm->verbose_medium()) | |
3503 gclog_or_tty->print_cr("[%d] we are scanning region " | |
3504 "["PTR_FORMAT", "PTR_FORMAT")", | |
3505 _task_id, mr.start(), mr.end()); | |
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3506 |
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3507 assert(mr.end() <= _cm->finger(), |
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3508 "otherwise the region shouldn't be on the stack"); |
342 | 3509 assert(!mr.is_empty(), "Only non-empty regions live on the region stack"); |
3510 if (_nextMarkBitMap->iterate(bc, mr)) { | |
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3511 assert(!has_aborted(), |
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3512 "cannot abort the task without aborting the bitmap iteration"); |
342 | 3513 |
3514 // We finished iterating over the region without aborting. | |
3515 regular_clock_call(); | |
3516 if (has_aborted()) | |
3517 mr = MemRegion(); | |
3518 else { | |
1835
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3519 mr = _cm->region_stack_pop_lock_free(); |
342 | 3520 // it returns MemRegion() if the pop fails |
3521 statsOnly(if (mr.start() != NULL) ++_region_stack_pops ); | |
3522 } | |
3523 } else { | |
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3524 assert(has_aborted(), "currently the only way to do so"); |
342 | 3525 |
3526 // The only way to abort the bitmap iteration is to return | |
3527 // false from the do_bit() method. However, inside the | |
3528 // do_bit() method we move the _region_finger to point to the | |
3529 // object currently being looked at. So, if we bail out, we | |
3530 // have definitely set _region_finger to something non-null. | |
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3531 assert(_region_finger != NULL, "invariant"); |
342 | 3532 |
1835
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3533 // Make sure that any previously aborted region has been |
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3534 // cleared. |
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3535 assert(_aborted_region.is_empty(), "aborted region not cleared"); |
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3536 |
342 | 3537 // The iteration was actually aborted. So now _region_finger |
3538 // points to the address of the object we last scanned. If we | |
3539 // leave it there, when we restart this task, we will rescan | |
3540 // the object. It is easy to avoid this. We move the finger by | |
3541 // enough to point to the next possible object header (the | |
3542 // bitmap knows by how much we need to move it as it knows its | |
3543 // granularity). | |
3544 MemRegion newRegion = | |
3545 MemRegion(_nextMarkBitMap->nextWord(_region_finger), mr.end()); | |
3546 | |
3547 if (!newRegion.is_empty()) { | |
3548 if (_cm->verbose_low()) { | |
1835
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3549 gclog_or_tty->print_cr("[%d] recording unscanned region" |
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3550 "[" PTR_FORMAT "," PTR_FORMAT ") in CMTask", |
342 | 3551 _task_id, |
3552 newRegion.start(), newRegion.end()); | |
3553 } | |
1835
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3554 // Now record the part of the region we didn't scan to |
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3555 // make sure this task scans it later. |
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3556 _aborted_region = newRegion; |
342 | 3557 } |
3558 // break from while | |
3559 mr = MemRegion(); | |
3560 } | |
3561 _region_finger = NULL; | |
3562 } | |
3563 | |
3564 if (_cm->verbose_low()) | |
3565 gclog_or_tty->print_cr("[%d] drained region stack, size = %d", | |
3566 _task_id, _cm->region_stack_size()); | |
3567 } | |
3568 } | |
3569 | |
3570 void CMTask::print_stats() { | |
3571 gclog_or_tty->print_cr("Marking Stats, task = %d, calls = %d", | |
3572 _task_id, _calls); | |
3573 gclog_or_tty->print_cr(" Elapsed time = %1.2lfms, Termination time = %1.2lfms", | |
3574 _elapsed_time_ms, _termination_time_ms); | |
3575 gclog_or_tty->print_cr(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms", | |
3576 _step_times_ms.num(), _step_times_ms.avg(), | |
3577 _step_times_ms.sd()); | |
3578 gclog_or_tty->print_cr(" max = %1.2lfms, total = %1.2lfms", | |
3579 _step_times_ms.maximum(), _step_times_ms.sum()); | |
3580 | |
3581 #if _MARKING_STATS_ | |
3582 gclog_or_tty->print_cr(" Clock Intervals (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms", | |
3583 _all_clock_intervals_ms.num(), _all_clock_intervals_ms.avg(), | |
3584 _all_clock_intervals_ms.sd()); | |
3585 gclog_or_tty->print_cr(" max = %1.2lfms, total = %1.2lfms", | |
3586 _all_clock_intervals_ms.maximum(), | |
3587 _all_clock_intervals_ms.sum()); | |
3588 gclog_or_tty->print_cr(" Clock Causes (cum): scanning = %d, marking = %d", | |
3589 _clock_due_to_scanning, _clock_due_to_marking); | |
3590 gclog_or_tty->print_cr(" Objects: scanned = %d, found on the bitmap = %d", | |
3591 _objs_scanned, _objs_found_on_bitmap); | |
3592 gclog_or_tty->print_cr(" Local Queue: pushes = %d, pops = %d, max size = %d", | |
3593 _local_pushes, _local_pops, _local_max_size); | |
3594 gclog_or_tty->print_cr(" Global Stack: pushes = %d, pops = %d, max size = %d", | |
3595 _global_pushes, _global_pops, _global_max_size); | |
3596 gclog_or_tty->print_cr(" transfers to = %d, transfers from = %d", | |
3597 _global_transfers_to,_global_transfers_from); | |
3598 gclog_or_tty->print_cr(" Regions: claimed = %d, Region Stack: pops = %d", | |
3599 _regions_claimed, _region_stack_pops); | |
3600 gclog_or_tty->print_cr(" SATB buffers: processed = %d", _satb_buffers_processed); | |
3601 gclog_or_tty->print_cr(" Steals: attempts = %d, successes = %d", | |
3602 _steal_attempts, _steals); | |
3603 gclog_or_tty->print_cr(" Aborted: %d, due to", _aborted); | |
3604 gclog_or_tty->print_cr(" overflow: %d, global abort: %d, yield: %d", | |
3605 _aborted_overflow, _aborted_cm_aborted, _aborted_yield); | |
3606 gclog_or_tty->print_cr(" time out: %d, SATB: %d, termination: %d", | |
3607 _aborted_timed_out, _aborted_satb, _aborted_termination); | |
3608 #endif // _MARKING_STATS_ | |
3609 } | |
3610 | |
3611 /***************************************************************************** | |
3612 | |
3613 The do_marking_step(time_target_ms) method is the building block | |
3614 of the parallel marking framework. It can be called in parallel | |
3615 with other invocations of do_marking_step() on different tasks | |
3616 (but only one per task, obviously) and concurrently with the | |
3617 mutator threads, or during remark, hence it eliminates the need | |
3618 for two versions of the code. When called during remark, it will | |
3619 pick up from where the task left off during the concurrent marking | |
3620 phase. Interestingly, tasks are also claimable during evacuation | |
3621 pauses too, since do_marking_step() ensures that it aborts before | |
3622 it needs to yield. | |
3623 | |
3624 The data structures that is uses to do marking work are the | |
3625 following: | |
3626 | |
3627 (1) Marking Bitmap. If there are gray objects that appear only | |
3628 on the bitmap (this happens either when dealing with an overflow | |
3629 or when the initial marking phase has simply marked the roots | |
3630 and didn't push them on the stack), then tasks claim heap | |
3631 regions whose bitmap they then scan to find gray objects. A | |
3632 global finger indicates where the end of the last claimed region | |
3633 is. A local finger indicates how far into the region a task has | |
3634 scanned. The two fingers are used to determine how to gray an | |
3635 object (i.e. whether simply marking it is OK, as it will be | |
3636 visited by a task in the future, or whether it needs to be also | |
3637 pushed on a stack). | |
3638 | |
3639 (2) Local Queue. The local queue of the task which is accessed | |
3640 reasonably efficiently by the task. Other tasks can steal from | |
3641 it when they run out of work. Throughout the marking phase, a | |
3642 task attempts to keep its local queue short but not totally | |
3643 empty, so that entries are available for stealing by other | |
3644 tasks. Only when there is no more work, a task will totally | |
3645 drain its local queue. | |
3646 | |
3647 (3) Global Mark Stack. This handles local queue overflow. During | |
3648 marking only sets of entries are moved between it and the local | |
3649 queues, as access to it requires a mutex and more fine-grain | |
3650 interaction with it which might cause contention. If it | |
3651 overflows, then the marking phase should restart and iterate | |
3652 over the bitmap to identify gray objects. Throughout the marking | |
3653 phase, tasks attempt to keep the global mark stack at a small | |
3654 length but not totally empty, so that entries are available for | |
3655 popping by other tasks. Only when there is no more work, tasks | |
3656 will totally drain the global mark stack. | |
3657 | |
3658 (4) Global Region Stack. Entries on it correspond to areas of | |
3659 the bitmap that need to be scanned since they contain gray | |
3660 objects. Pushes on the region stack only happen during | |
3661 evacuation pauses and typically correspond to areas covered by | |
3662 GC LABS. If it overflows, then the marking phase should restart | |
3663 and iterate over the bitmap to identify gray objects. Tasks will | |
3664 try to totally drain the region stack as soon as possible. | |
3665 | |
3666 (5) SATB Buffer Queue. This is where completed SATB buffers are | |
3667 made available. Buffers are regularly removed from this queue | |
3668 and scanned for roots, so that the queue doesn't get too | |
3669 long. During remark, all completed buffers are processed, as | |
3670 well as the filled in parts of any uncompleted buffers. | |
3671 | |
3672 The do_marking_step() method tries to abort when the time target | |
3673 has been reached. There are a few other cases when the | |
3674 do_marking_step() method also aborts: | |
3675 | |
3676 (1) When the marking phase has been aborted (after a Full GC). | |
3677 | |
3678 (2) When a global overflow (either on the global stack or the | |
3679 region stack) has been triggered. Before the task aborts, it | |
3680 will actually sync up with the other tasks to ensure that all | |
3681 the marking data structures (local queues, stacks, fingers etc.) | |
3682 are re-initialised so that when do_marking_step() completes, | |
3683 the marking phase can immediately restart. | |
3684 | |
3685 (3) When enough completed SATB buffers are available. The | |
3686 do_marking_step() method only tries to drain SATB buffers right | |
3687 at the beginning. So, if enough buffers are available, the | |
3688 marking step aborts and the SATB buffers are processed at | |
3689 the beginning of the next invocation. | |
3690 | |
3691 (4) To yield. when we have to yield then we abort and yield | |
3692 right at the end of do_marking_step(). This saves us from a lot | |
3693 of hassle as, by yielding we might allow a Full GC. If this | |
3694 happens then objects will be compacted underneath our feet, the | |
3695 heap might shrink, etc. We save checking for this by just | |
3696 aborting and doing the yield right at the end. | |
3697 | |
3698 From the above it follows that the do_marking_step() method should | |
3699 be called in a loop (or, otherwise, regularly) until it completes. | |
3700 | |
3701 If a marking step completes without its has_aborted() flag being | |
3702 true, it means it has completed the current marking phase (and | |
3703 also all other marking tasks have done so and have all synced up). | |
3704 | |
3705 A method called regular_clock_call() is invoked "regularly" (in | |
3706 sub ms intervals) throughout marking. It is this clock method that | |
3707 checks all the abort conditions which were mentioned above and | |
3708 decides when the task should abort. A work-based scheme is used to | |
3709 trigger this clock method: when the number of object words the | |
3710 marking phase has scanned or the number of references the marking | |
3711 phase has visited reach a given limit. Additional invocations to | |
3712 the method clock have been planted in a few other strategic places | |
3713 too. The initial reason for the clock method was to avoid calling | |
3714 vtime too regularly, as it is quite expensive. So, once it was in | |
3715 place, it was natural to piggy-back all the other conditions on it | |
3716 too and not constantly check them throughout the code. | |
3717 | |
3718 *****************************************************************************/ | |
3719 | |
3720 void CMTask::do_marking_step(double time_target_ms) { | |
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3721 assert(time_target_ms >= 1.0, "minimum granularity is 1ms"); |
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3722 assert(concurrent() == _cm->concurrent(), "they should be the same"); |
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3723 |
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3724 assert(concurrent() || _cm->region_stack_empty(), |
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3725 "the region stack should have been cleared before remark"); |
1835
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3726 assert(concurrent() || !_cm->has_aborted_regions(), |
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3727 "aborted regions should have been cleared before remark"); |
1023
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3728 assert(_region_finger == NULL, |
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3729 "this should be non-null only when a region is being scanned"); |
342 | 3730 |
3731 G1CollectorPolicy* g1_policy = _g1h->g1_policy(); | |
1023
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3732 assert(_task_queues != NULL, "invariant"); |
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3733 assert(_task_queue != NULL, "invariant"); |
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3734 assert(_task_queues->queue(_task_id) == _task_queue, "invariant"); |
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3735 |
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3736 assert(!_claimed, |
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3737 "only one thread should claim this task at any one time"); |
342 | 3738 |
3739 // OK, this doesn't safeguard again all possible scenarios, as it is | |
3740 // possible for two threads to set the _claimed flag at the same | |
3741 // time. But it is only for debugging purposes anyway and it will | |
3742 // catch most problems. | |
3743 _claimed = true; | |
3744 | |
3745 _start_time_ms = os::elapsedVTime() * 1000.0; | |
3746 statsOnly( _interval_start_time_ms = _start_time_ms ); | |
3747 | |
3748 double diff_prediction_ms = | |
3749 g1_policy->get_new_prediction(&_marking_step_diffs_ms); | |
3750 _time_target_ms = time_target_ms - diff_prediction_ms; | |
3751 | |
3752 // set up the variables that are used in the work-based scheme to | |
3753 // call the regular clock method | |
3754 _words_scanned = 0; | |
3755 _refs_reached = 0; | |
3756 recalculate_limits(); | |
3757 | |
3758 // clear all flags | |
3759 clear_has_aborted(); | |
3760 _has_aborted_timed_out = false; | |
3761 _draining_satb_buffers = false; | |
3762 | |
3763 ++_calls; | |
3764 | |
3765 if (_cm->verbose_low()) | |
3766 gclog_or_tty->print_cr("[%d] >>>>>>>>>> START, call = %d, " | |
3767 "target = %1.2lfms >>>>>>>>>>", | |
3768 _task_id, _calls, _time_target_ms); | |
3769 | |
3770 // Set up the bitmap and oop closures. Anything that uses them is | |
3771 // eventually called from this method, so it is OK to allocate these | |
3772 // statically. | |
3773 CMBitMapClosure bitmap_closure(this, _cm, _nextMarkBitMap); | |
3774 CMOopClosure oop_closure(_g1h, _cm, this); | |
3775 set_oop_closure(&oop_closure); | |
3776 | |
3777 if (_cm->has_overflown()) { | |
3778 // This can happen if the region stack or the mark stack overflows | |
3779 // during a GC pause and this task, after a yield point, | |
3780 // restarts. We have to abort as we need to get into the overflow | |
3781 // protocol which happens right at the end of this task. | |
3782 set_has_aborted(); | |
3783 } | |
3784 | |
3785 // First drain any available SATB buffers. After this, we will not | |
3786 // look at SATB buffers before the next invocation of this method. | |
3787 // If enough completed SATB buffers are queued up, the regular clock | |
3788 // will abort this task so that it restarts. | |
3789 drain_satb_buffers(); | |
3790 // ...then partially drain the local queue and the global stack | |
3791 drain_local_queue(true); | |
3792 drain_global_stack(true); | |
3793 | |
3794 // Then totally drain the region stack. We will not look at | |
3795 // it again before the next invocation of this method. Entries on | |
3796 // the region stack are only added during evacuation pauses, for | |
3797 // which we have to yield. When we do, we abort the task anyway so | |
3798 // it will look at the region stack again when it restarts. | |
3799 bitmap_closure.set_scanning_heap_region(false); | |
3800 drain_region_stack(&bitmap_closure); | |
3801 // ...then partially drain the local queue and the global stack | |
3802 drain_local_queue(true); | |
3803 drain_global_stack(true); | |
3804 | |
3805 do { | |
3806 if (!has_aborted() && _curr_region != NULL) { | |
3807 // This means that we're already holding on to a region. | |
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3808 assert(_finger != NULL, "if region is not NULL, then the finger " |
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3809 "should not be NULL either"); |
342 | 3810 |
3811 // We might have restarted this task after an evacuation pause | |
3812 // which might have evacuated the region we're holding on to | |
3813 // underneath our feet. Let's read its limit again to make sure | |
3814 // that we do not iterate over a region of the heap that | |
3815 // contains garbage (update_region_limit() will also move | |
3816 // _finger to the start of the region if it is found empty). | |
3817 update_region_limit(); | |
3818 // We will start from _finger not from the start of the region, | |
3819 // as we might be restarting this task after aborting half-way | |
3820 // through scanning this region. In this case, _finger points to | |
3821 // the address where we last found a marked object. If this is a | |
3822 // fresh region, _finger points to start(). | |
3823 MemRegion mr = MemRegion(_finger, _region_limit); | |
3824 | |
3825 if (_cm->verbose_low()) | |
3826 gclog_or_tty->print_cr("[%d] we're scanning part " | |
3827 "["PTR_FORMAT", "PTR_FORMAT") " | |
3828 "of region "PTR_FORMAT, | |
3829 _task_id, _finger, _region_limit, _curr_region); | |
3830 | |
3831 // Let's iterate over the bitmap of the part of the | |
3832 // region that is left. | |
3833 bitmap_closure.set_scanning_heap_region(true); | |
3834 if (mr.is_empty() || | |
3835 _nextMarkBitMap->iterate(&bitmap_closure, mr)) { | |
3836 // We successfully completed iterating over the region. Now, | |
3837 // let's give up the region. | |
3838 giveup_current_region(); | |
3839 regular_clock_call(); | |
3840 } else { | |
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3841 assert(has_aborted(), "currently the only way to do so"); |
342 | 3842 // The only way to abort the bitmap iteration is to return |
3843 // false from the do_bit() method. However, inside the | |
3844 // do_bit() method we move the _finger to point to the | |
3845 // object currently being looked at. So, if we bail out, we | |
3846 // have definitely set _finger to something non-null. | |
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3847 assert(_finger != NULL, "invariant"); |
342 | 3848 |
3849 // Region iteration was actually aborted. So now _finger | |
3850 // points to the address of the object we last scanned. If we | |
3851 // leave it there, when we restart this task, we will rescan | |
3852 // the object. It is easy to avoid this. We move the finger by | |
3853 // enough to point to the next possible object header (the | |
3854 // bitmap knows by how much we need to move it as it knows its | |
3855 // granularity). | |
1314
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3856 assert(_finger < _region_limit, "invariant"); |
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3857 HeapWord* new_finger = _nextMarkBitMap->nextWord(_finger); |
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3858 // Check if bitmap iteration was aborted while scanning the last object |
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3859 if (new_finger >= _region_limit) { |
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3860 giveup_current_region(); |
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3861 } else { |
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3862 move_finger_to(new_finger); |
3f0549ed0c98
6921710: G1: assert(new_finger >= _finger && new_finger < _region_limit,"invariant")
apetrusenko
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|
3863 } |
342 | 3864 } |
3865 } | |
3866 // At this point we have either completed iterating over the | |
3867 // region we were holding on to, or we have aborted. | |
3868 | |
3869 // We then partially drain the local queue and the global stack. | |
3870 // (Do we really need this?) | |
3871 drain_local_queue(true); | |
3872 drain_global_stack(true); | |
3873 | |
3874 // Read the note on the claim_region() method on why it might | |
3875 // return NULL with potentially more regions available for | |
3876 // claiming and why we have to check out_of_regions() to determine | |
3877 // whether we're done or not. | |
3878 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) { | |
3879 // We are going to try to claim a new region. We should have | |
3880 // given up on the previous one. | |
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3881 // Separated the asserts so that we know which one fires. |
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3882 assert(_curr_region == NULL, "invariant"); |
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3883 assert(_finger == NULL, "invariant"); |
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3884 assert(_region_limit == NULL, "invariant"); |
342 | 3885 if (_cm->verbose_low()) |
3886 gclog_or_tty->print_cr("[%d] trying to claim a new region", _task_id); | |
3887 HeapRegion* claimed_region = _cm->claim_region(_task_id); | |
3888 if (claimed_region != NULL) { | |
3889 // Yes, we managed to claim one | |
3890 statsOnly( ++_regions_claimed ); | |
3891 | |
3892 if (_cm->verbose_low()) | |
3893 gclog_or_tty->print_cr("[%d] we successfully claimed " | |
3894 "region "PTR_FORMAT, | |
3895 _task_id, claimed_region); | |
3896 | |
3897 setup_for_region(claimed_region); | |
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3898 assert(_curr_region == claimed_region, "invariant"); |
342 | 3899 } |
3900 // It is important to call the regular clock here. It might take | |
3901 // a while to claim a region if, for example, we hit a large | |
3902 // block of empty regions. So we need to call the regular clock | |
3903 // method once round the loop to make sure it's called | |
3904 // frequently enough. | |
3905 regular_clock_call(); | |
3906 } | |
3907 | |
3908 if (!has_aborted() && _curr_region == NULL) { | |
1023
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|
3909 assert(_cm->out_of_regions(), |
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3910 "at this point we should be out of regions"); |
342 | 3911 } |
3912 } while ( _curr_region != NULL && !has_aborted()); | |
3913 | |
3914 if (!has_aborted()) { | |
3915 // We cannot check whether the global stack is empty, since other | |
343
afc1ce1efe66
6710665: G1: guarantee(_cm->out_of_regions() && _cm->region_stack_empty() && _task_queue->size() == 0, ...)
iveresov
parents:
342
diff
changeset
|
3916 // tasks might be pushing objects to it concurrently. We also cannot |
afc1ce1efe66
6710665: G1: guarantee(_cm->out_of_regions() && _cm->region_stack_empty() && _task_queue->size() == 0, ...)
iveresov
parents:
342
diff
changeset
|
3917 // check if the region stack is empty because if a thread is aborting |
afc1ce1efe66
6710665: G1: guarantee(_cm->out_of_regions() && _cm->region_stack_empty() && _task_queue->size() == 0, ...)
iveresov
parents:
342
diff
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|
3918 // it can push a partially done region back. |
1023
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3919 assert(_cm->out_of_regions(), |
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3920 "at this point we should be out of regions"); |
342 | 3921 |
3922 if (_cm->verbose_low()) | |
3923 gclog_or_tty->print_cr("[%d] all regions claimed", _task_id); | |
3924 | |
3925 // Try to reduce the number of available SATB buffers so that | |
3926 // remark has less work to do. | |
3927 drain_satb_buffers(); | |
3928 } | |
3929 | |
3930 // Since we've done everything else, we can now totally drain the | |
3931 // local queue and global stack. | |
3932 drain_local_queue(false); | |
3933 drain_global_stack(false); | |
3934 | |
3935 // Attempt at work stealing from other task's queues. | |
3936 if (!has_aborted()) { | |
3937 // We have not aborted. This means that we have finished all that | |
3938 // we could. Let's try to do some stealing... | |
3939 | |
3940 // We cannot check whether the global stack is empty, since other | |
343
afc1ce1efe66
6710665: G1: guarantee(_cm->out_of_regions() && _cm->region_stack_empty() && _task_queue->size() == 0, ...)
iveresov
parents:
342
diff
changeset
|
3941 // tasks might be pushing objects to it concurrently. We also cannot |
afc1ce1efe66
6710665: G1: guarantee(_cm->out_of_regions() && _cm->region_stack_empty() && _task_queue->size() == 0, ...)
iveresov
parents:
342
diff
changeset
|
3942 // check if the region stack is empty because if a thread is aborting |
afc1ce1efe66
6710665: G1: guarantee(_cm->out_of_regions() && _cm->region_stack_empty() && _task_queue->size() == 0, ...)
iveresov
parents:
342
diff
changeset
|
3943 // it can push a partially done region back. |
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3944 assert(_cm->out_of_regions() && _task_queue->size() == 0, |
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3945 "only way to reach here"); |
342 | 3946 |
3947 if (_cm->verbose_low()) | |
3948 gclog_or_tty->print_cr("[%d] starting to steal", _task_id); | |
3949 | |
3950 while (!has_aborted()) { | |
3951 oop obj; | |
3952 statsOnly( ++_steal_attempts ); | |
3953 | |
3954 if (_cm->try_stealing(_task_id, &_hash_seed, obj)) { | |
3955 if (_cm->verbose_medium()) | |
3956 gclog_or_tty->print_cr("[%d] stolen "PTR_FORMAT" successfully", | |
3957 _task_id, (void*) obj); | |
3958 | |
3959 statsOnly( ++_steals ); | |
3960 | |
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3961 assert(_nextMarkBitMap->isMarked((HeapWord*) obj), |
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3962 "any stolen object should be marked"); |
342 | 3963 scan_object(obj); |
3964 | |
3965 // And since we're towards the end, let's totally drain the | |
3966 // local queue and global stack. | |
3967 drain_local_queue(false); | |
3968 drain_global_stack(false); | |
3969 } else { | |
3970 break; | |
3971 } | |
3972 } | |
3973 } | |
3974 | |
3975 // We still haven't aborted. Now, let's try to get into the | |
3976 // termination protocol. | |
3977 if (!has_aborted()) { | |
3978 // We cannot check whether the global stack is empty, since other | |
343
afc1ce1efe66
6710665: G1: guarantee(_cm->out_of_regions() && _cm->region_stack_empty() && _task_queue->size() == 0, ...)
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parents:
342
diff
changeset
|
3979 // tasks might be concurrently pushing objects on it. We also cannot |
afc1ce1efe66
6710665: G1: guarantee(_cm->out_of_regions() && _cm->region_stack_empty() && _task_queue->size() == 0, ...)
iveresov
parents:
342
diff
changeset
|
3980 // check if the region stack is empty because if a thread is aborting |
afc1ce1efe66
6710665: G1: guarantee(_cm->out_of_regions() && _cm->region_stack_empty() && _task_queue->size() == 0, ...)
iveresov
parents:
342
diff
changeset
|
3981 // it can push a partially done region back. |
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3982 // Separated the asserts so that we know which one fires. |
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3983 assert(_cm->out_of_regions(), "only way to reach here"); |
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3984 assert(_task_queue->size() == 0, "only way to reach here"); |
342 | 3985 |
3986 if (_cm->verbose_low()) | |
3987 gclog_or_tty->print_cr("[%d] starting termination protocol", _task_id); | |
3988 | |
3989 _termination_start_time_ms = os::elapsedVTime() * 1000.0; | |
3990 // The CMTask class also extends the TerminatorTerminator class, | |
3991 // hence its should_exit_termination() method will also decide | |
3992 // whether to exit the termination protocol or not. | |
3993 bool finished = _cm->terminator()->offer_termination(this); | |
3994 double termination_end_time_ms = os::elapsedVTime() * 1000.0; | |
3995 _termination_time_ms += | |
3996 termination_end_time_ms - _termination_start_time_ms; | |
3997 | |
3998 if (finished) { | |
3999 // We're all done. | |
4000 | |
4001 if (_task_id == 0) { | |
4002 // let's allow task 0 to do this | |
4003 if (concurrent()) { | |
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4004 assert(_cm->concurrent_marking_in_progress(), "invariant"); |
342 | 4005 // we need to set this to false before the next |
4006 // safepoint. This way we ensure that the marking phase | |
4007 // doesn't observe any more heap expansions. | |
4008 _cm->clear_concurrent_marking_in_progress(); | |
4009 } | |
4010 } | |
4011 | |
4012 // We can now guarantee that the global stack is empty, since | |
1023
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|
4013 // all other tasks have finished. We separated the guarantees so |
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|
4014 // that, if a condition is false, we can immediately find out |
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|
4015 // which one. |
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4016 guarantee(_cm->out_of_regions(), "only way to reach here"); |
1835
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6941395: G1: Use only lock-free versions of region stack push() and pop()
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1833
diff
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|
4017 guarantee(_aborted_region.is_empty(), "only way to reach here"); |
1023
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|
4018 guarantee(_cm->region_stack_empty(), "only way to reach here"); |
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4019 guarantee(_cm->mark_stack_empty(), "only way to reach here"); |
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4020 guarantee(_task_queue->size() == 0, "only way to reach here"); |
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4021 guarantee(!_cm->has_overflown(), "only way to reach here"); |
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|
4022 guarantee(!_cm->mark_stack_overflow(), "only way to reach here"); |
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|
4023 guarantee(!_cm->region_stack_overflow(), "only way to reach here"); |
342 | 4024 |
4025 if (_cm->verbose_low()) | |
4026 gclog_or_tty->print_cr("[%d] all tasks terminated", _task_id); | |
4027 } else { | |
4028 // Apparently there's more work to do. Let's abort this task. It | |
4029 // will restart it and we can hopefully find more things to do. | |
4030 | |
4031 if (_cm->verbose_low()) | |
4032 gclog_or_tty->print_cr("[%d] apparently there is more work to do", _task_id); | |
4033 | |
4034 set_has_aborted(); | |
4035 statsOnly( ++_aborted_termination ); | |
4036 } | |
4037 } | |
4038 | |
4039 // Mainly for debugging purposes to make sure that a pointer to the | |
4040 // closure which was statically allocated in this frame doesn't | |
4041 // escape it by accident. | |
4042 set_oop_closure(NULL); | |
4043 double end_time_ms = os::elapsedVTime() * 1000.0; | |
4044 double elapsed_time_ms = end_time_ms - _start_time_ms; | |
4045 // Update the step history. | |
4046 _step_times_ms.add(elapsed_time_ms); | |
4047 | |
4048 if (has_aborted()) { | |
4049 // The task was aborted for some reason. | |
4050 | |
4051 statsOnly( ++_aborted ); | |
4052 | |
4053 if (_has_aborted_timed_out) { | |
4054 double diff_ms = elapsed_time_ms - _time_target_ms; | |
4055 // Keep statistics of how well we did with respect to hitting | |
4056 // our target only if we actually timed out (if we aborted for | |
4057 // other reasons, then the results might get skewed). | |
4058 _marking_step_diffs_ms.add(diff_ms); | |
4059 } | |
4060 | |
4061 if (_cm->has_overflown()) { | |
4062 // This is the interesting one. We aborted because a global | |
4063 // overflow was raised. This means we have to restart the | |
4064 // marking phase and start iterating over regions. However, in | |
4065 // order to do this we have to make sure that all tasks stop | |
4066 // what they are doing and re-initialise in a safe manner. We | |
4067 // will achieve this with the use of two barrier sync points. | |
4068 | |
4069 if (_cm->verbose_low()) | |
4070 gclog_or_tty->print_cr("[%d] detected overflow", _task_id); | |
4071 | |
4072 _cm->enter_first_sync_barrier(_task_id); | |
4073 // When we exit this sync barrier we know that all tasks have | |
4074 // stopped doing marking work. So, it's now safe to | |
4075 // re-initialise our data structures. At the end of this method, | |
4076 // task 0 will clear the global data structures. | |
4077 | |
4078 statsOnly( ++_aborted_overflow ); | |
4079 | |
4080 // We clear the local state of this task... | |
4081 clear_region_fields(); | |
4082 | |
4083 // ...and enter the second barrier. | |
4084 _cm->enter_second_sync_barrier(_task_id); | |
4085 // At this point everything has bee re-initialised and we're | |
4086 // ready to restart. | |
4087 } | |
4088 | |
4089 if (_cm->verbose_low()) { | |
4090 gclog_or_tty->print_cr("[%d] <<<<<<<<<< ABORTING, target = %1.2lfms, " | |
4091 "elapsed = %1.2lfms <<<<<<<<<<", | |
4092 _task_id, _time_target_ms, elapsed_time_ms); | |
4093 if (_cm->has_aborted()) | |
4094 gclog_or_tty->print_cr("[%d] ========== MARKING ABORTED ==========", | |
4095 _task_id); | |
4096 } | |
4097 } else { | |
4098 if (_cm->verbose_low()) | |
4099 gclog_or_tty->print_cr("[%d] <<<<<<<<<< FINISHED, target = %1.2lfms, " | |
4100 "elapsed = %1.2lfms <<<<<<<<<<", | |
4101 _task_id, _time_target_ms, elapsed_time_ms); | |
4102 } | |
4103 | |
4104 _claimed = false; | |
4105 } | |
4106 | |
4107 CMTask::CMTask(int task_id, | |
4108 ConcurrentMark* cm, | |
4109 CMTaskQueue* task_queue, | |
4110 CMTaskQueueSet* task_queues) | |
4111 : _g1h(G1CollectedHeap::heap()), | |
4112 _task_id(task_id), _cm(cm), | |
4113 _claimed(false), | |
4114 _nextMarkBitMap(NULL), _hash_seed(17), | |
4115 _task_queue(task_queue), | |
4116 _task_queues(task_queues), | |
1835
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johnc
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1833
diff
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|
4117 _oop_closure(NULL), |
4805b9f4779e
6941395: G1: Use only lock-free versions of region stack push() and pop()
johnc
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1833
diff
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|
4118 _aborted_region(MemRegion()) { |
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|
4119 guarantee(task_queue != NULL, "invariant"); |
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|
4120 guarantee(task_queues != NULL, "invariant"); |
342 | 4121 |
4122 statsOnly( _clock_due_to_scanning = 0; | |
4123 _clock_due_to_marking = 0 ); | |
4124 | |
4125 _marking_step_diffs_ms.add(0.5); | |
4126 } |