Mercurial > hg > graal-compiler
annotate src/share/vm/gc_implementation/parNew/parNewGeneration.cpp @ 6595:aaf61e68b255
6818524: G1: use ergonomic resizing of PLABs
Summary: Employ PLABStats instances to record information about survivor and old PLABs, and use the recorded stats to adjust the sizes of survivor and old PLABS.
Reviewed-by: johnc, ysr
Contributed-by: Brandon Mitchell <brandon@twitter.com>
author | johnc |
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date | Mon, 06 Aug 2012 12:20:14 -0700 |
parents | d2a62e0f25eb |
children | da91efe96a93 |
rev | line source |
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0 | 1 /* |
4911 | 2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved. |
0 | 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. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp" | |
27 #include "gc_implementation/parNew/parNewGeneration.hpp" | |
28 #include "gc_implementation/parNew/parOopClosures.inline.hpp" | |
29 #include "gc_implementation/shared/adaptiveSizePolicy.hpp" | |
30 #include "gc_implementation/shared/ageTable.hpp" | |
6595 | 31 #include "gc_implementation/shared/parGCAllocBuffer.hpp" |
1972 | 32 #include "gc_implementation/shared/spaceDecorator.hpp" |
33 #include "memory/defNewGeneration.inline.hpp" | |
34 #include "memory/genCollectedHeap.hpp" | |
35 #include "memory/genOopClosures.inline.hpp" | |
36 #include "memory/generation.hpp" | |
37 #include "memory/generation.inline.hpp" | |
38 #include "memory/referencePolicy.hpp" | |
39 #include "memory/resourceArea.hpp" | |
40 #include "memory/sharedHeap.hpp" | |
41 #include "memory/space.hpp" | |
42 #include "oops/objArrayOop.hpp" | |
43 #include "oops/oop.inline.hpp" | |
44 #include "oops/oop.pcgc.inline.hpp" | |
45 #include "runtime/handles.hpp" | |
46 #include "runtime/handles.inline.hpp" | |
47 #include "runtime/java.hpp" | |
48 #include "runtime/thread.hpp" | |
49 #include "utilities/copy.hpp" | |
50 #include "utilities/globalDefinitions.hpp" | |
51 #include "utilities/workgroup.hpp" | |
0 | 52 |
53 #ifdef _MSC_VER | |
54 #pragma warning( push ) | |
55 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list | |
56 #endif | |
57 ParScanThreadState::ParScanThreadState(Space* to_space_, | |
58 ParNewGeneration* gen_, | |
59 Generation* old_gen_, | |
60 int thread_num_, | |
61 ObjToScanQueueSet* work_queue_set_, | |
6197 | 62 Stack<oop, mtGC>* overflow_stacks_, |
0 | 63 size_t desired_plab_sz_, |
64 ParallelTaskTerminator& term_) : | |
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65 _to_space(to_space_), _old_gen(old_gen_), _young_gen(gen_), _thread_num(thread_num_), |
0 | 66 _work_queue(work_queue_set_->queue(thread_num_)), _to_space_full(false), |
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67 _overflow_stack(overflow_stacks_ ? overflow_stacks_ + thread_num_ : NULL), |
0 | 68 _ageTable(false), // false ==> not the global age table, no perf data. |
69 _to_space_alloc_buffer(desired_plab_sz_), | |
70 _to_space_closure(gen_, this), _old_gen_closure(gen_, this), | |
71 _to_space_root_closure(gen_, this), _old_gen_root_closure(gen_, this), | |
72 _older_gen_closure(gen_, this), | |
73 _evacuate_followers(this, &_to_space_closure, &_old_gen_closure, | |
74 &_to_space_root_closure, gen_, &_old_gen_root_closure, | |
75 work_queue_set_, &term_), | |
76 _is_alive_closure(gen_), _scan_weak_ref_closure(gen_, this), | |
77 _keep_alive_closure(&_scan_weak_ref_closure), | |
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78 _promotion_failure_size(0), |
0 | 79 _strong_roots_time(0.0), _term_time(0.0) |
80 { | |
1710 | 81 #if TASKQUEUE_STATS |
82 _term_attempts = 0; | |
83 _overflow_refills = 0; | |
84 _overflow_refill_objs = 0; | |
85 #endif // TASKQUEUE_STATS | |
86 | |
0 | 87 _survivor_chunk_array = |
88 (ChunkArray*) old_gen()->get_data_recorder(thread_num()); | |
89 _hash_seed = 17; // Might want to take time-based random value. | |
90 _start = os::elapsedTime(); | |
91 _old_gen_closure.set_generation(old_gen_); | |
92 _old_gen_root_closure.set_generation(old_gen_); | |
93 } | |
94 #ifdef _MSC_VER | |
95 #pragma warning( pop ) | |
96 #endif | |
97 | |
98 void ParScanThreadState::record_survivor_plab(HeapWord* plab_start, | |
99 size_t plab_word_size) { | |
100 ChunkArray* sca = survivor_chunk_array(); | |
101 if (sca != NULL) { | |
102 // A non-null SCA implies that we want the PLAB data recorded. | |
103 sca->record_sample(plab_start, plab_word_size); | |
104 } | |
105 } | |
106 | |
107 bool ParScanThreadState::should_be_partially_scanned(oop new_obj, oop old_obj) const { | |
108 return new_obj->is_objArray() && | |
109 arrayOop(new_obj)->length() > ParGCArrayScanChunk && | |
110 new_obj != old_obj; | |
111 } | |
112 | |
113 void ParScanThreadState::scan_partial_array_and_push_remainder(oop old) { | |
114 assert(old->is_objArray(), "must be obj array"); | |
115 assert(old->is_forwarded(), "must be forwarded"); | |
116 assert(Universe::heap()->is_in_reserved(old), "must be in heap."); | |
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117 assert(!old_gen()->is_in(old), "must be in young generation."); |
0 | 118 |
119 objArrayOop obj = objArrayOop(old->forwardee()); | |
120 // Process ParGCArrayScanChunk elements now | |
121 // and push the remainder back onto queue | |
122 int start = arrayOop(old)->length(); | |
123 int end = obj->length(); | |
124 int remainder = end - start; | |
125 assert(start <= end, "just checking"); | |
126 if (remainder > 2 * ParGCArrayScanChunk) { | |
127 // Test above combines last partial chunk with a full chunk | |
128 end = start + ParGCArrayScanChunk; | |
129 arrayOop(old)->set_length(end); | |
130 // Push remainder. | |
131 bool ok = work_queue()->push(old); | |
132 assert(ok, "just popped, push must be okay"); | |
133 } else { | |
134 // Restore length so that it can be used if there | |
135 // is a promotion failure and forwarding pointers | |
136 // must be removed. | |
137 arrayOop(old)->set_length(end); | |
138 } | |
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139 |
0 | 140 // process our set of indices (include header in first chunk) |
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141 // should make sure end is even (aligned to HeapWord in case of compressed oops) |
0 | 142 if ((HeapWord *)obj < young_old_boundary()) { |
143 // object is in to_space | |
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144 obj->oop_iterate_range(&_to_space_closure, start, end); |
0 | 145 } else { |
146 // object is in old generation | |
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147 obj->oop_iterate_range(&_old_gen_closure, start, end); |
0 | 148 } |
149 } | |
150 | |
151 | |
152 void ParScanThreadState::trim_queues(int max_size) { | |
153 ObjToScanQueue* queue = work_queue(); | |
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154 do { |
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155 while (queue->size() > (juint)max_size) { |
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156 oop obj_to_scan; |
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157 if (queue->pop_local(obj_to_scan)) { |
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158 if ((HeapWord *)obj_to_scan < young_old_boundary()) { |
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159 if (obj_to_scan->is_objArray() && |
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160 obj_to_scan->is_forwarded() && |
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161 obj_to_scan->forwardee() != obj_to_scan) { |
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162 scan_partial_array_and_push_remainder(obj_to_scan); |
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163 } else { |
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164 // object is in to_space |
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165 obj_to_scan->oop_iterate(&_to_space_closure); |
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166 } |
0 | 167 } else { |
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168 // object is in old generation |
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169 obj_to_scan->oop_iterate(&_old_gen_closure); |
0 | 170 } |
171 } | |
172 } | |
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173 // For the case of compressed oops, we have a private, non-shared |
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174 // overflow stack, so we eagerly drain it so as to more evenly |
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175 // distribute load early. Note: this may be good to do in |
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176 // general rather than delay for the final stealing phase. |
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177 // If applicable, we'll transfer a set of objects over to our |
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178 // work queue, allowing them to be stolen and draining our |
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179 // private overflow stack. |
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180 } while (ParGCTrimOverflow && young_gen()->take_from_overflow_list(this)); |
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181 } |
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182 |
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183 bool ParScanThreadState::take_from_overflow_stack() { |
695 | 184 assert(ParGCUseLocalOverflow, "Else should not call"); |
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185 assert(young_gen()->overflow_list() == NULL, "Error"); |
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186 ObjToScanQueue* queue = work_queue(); |
6197 | 187 Stack<oop, mtGC>* const of_stack = overflow_stack(); |
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188 const size_t num_overflow_elems = of_stack->size(); |
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189 const size_t space_available = queue->max_elems() - queue->size(); |
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190 const size_t num_take_elems = MIN3(space_available / 4, |
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191 ParGCDesiredObjsFromOverflowList, |
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192 num_overflow_elems); |
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193 // Transfer the most recent num_take_elems from the overflow |
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194 // stack to our work queue. |
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195 for (size_t i = 0; i != num_take_elems; i++) { |
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196 oop cur = of_stack->pop(); |
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197 oop obj_to_push = cur->forwardee(); |
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198 assert(Universe::heap()->is_in_reserved(cur), "Should be in heap"); |
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199 assert(!old_gen()->is_in_reserved(cur), "Should be in young gen"); |
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200 assert(Universe::heap()->is_in_reserved(obj_to_push), "Should be in heap"); |
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201 if (should_be_partially_scanned(obj_to_push, cur)) { |
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202 assert(arrayOop(cur)->length() == 0, "entire array remaining to be scanned"); |
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203 obj_to_push = cur; |
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204 } |
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205 bool ok = queue->push(obj_to_push); |
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206 assert(ok, "Should have succeeded"); |
0 | 207 } |
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208 assert(young_gen()->overflow_list() == NULL, "Error"); |
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209 return num_take_elems > 0; // was something transferred? |
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210 } |
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211 |
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212 void ParScanThreadState::push_on_overflow_stack(oop p) { |
695 | 213 assert(ParGCUseLocalOverflow, "Else should not call"); |
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214 overflow_stack()->push(p); |
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215 assert(young_gen()->overflow_list() == NULL, "Error"); |
0 | 216 } |
217 | |
218 HeapWord* ParScanThreadState::alloc_in_to_space_slow(size_t word_sz) { | |
219 | |
220 // Otherwise, if the object is small enough, try to reallocate the | |
221 // buffer. | |
222 HeapWord* obj = NULL; | |
223 if (!_to_space_full) { | |
224 ParGCAllocBuffer* const plab = to_space_alloc_buffer(); | |
225 Space* const sp = to_space(); | |
226 if (word_sz * 100 < | |
227 ParallelGCBufferWastePct * plab->word_sz()) { | |
228 // Is small enough; abandon this buffer and start a new one. | |
229 plab->retire(false, false); | |
230 size_t buf_size = plab->word_sz(); | |
231 HeapWord* buf_space = sp->par_allocate(buf_size); | |
232 if (buf_space == NULL) { | |
233 const size_t min_bytes = | |
234 ParGCAllocBuffer::min_size() << LogHeapWordSize; | |
235 size_t free_bytes = sp->free(); | |
236 while(buf_space == NULL && free_bytes >= min_bytes) { | |
237 buf_size = free_bytes >> LogHeapWordSize; | |
238 assert(buf_size == (size_t)align_object_size(buf_size), | |
239 "Invariant"); | |
240 buf_space = sp->par_allocate(buf_size); | |
241 free_bytes = sp->free(); | |
242 } | |
243 } | |
244 if (buf_space != NULL) { | |
245 plab->set_word_size(buf_size); | |
246 plab->set_buf(buf_space); | |
247 record_survivor_plab(buf_space, buf_size); | |
248 obj = plab->allocate(word_sz); | |
249 // Note that we cannot compare buf_size < word_sz below | |
250 // because of AlignmentReserve (see ParGCAllocBuffer::allocate()). | |
251 assert(obj != NULL || plab->words_remaining() < word_sz, | |
252 "Else should have been able to allocate"); | |
253 // It's conceivable that we may be able to use the | |
254 // buffer we just grabbed for subsequent small requests | |
255 // even if not for this one. | |
256 } else { | |
257 // We're used up. | |
258 _to_space_full = true; | |
259 } | |
260 | |
261 } else { | |
262 // Too large; allocate the object individually. | |
263 obj = sp->par_allocate(word_sz); | |
264 } | |
265 } | |
266 return obj; | |
267 } | |
268 | |
269 | |
270 void ParScanThreadState::undo_alloc_in_to_space(HeapWord* obj, | |
271 size_t word_sz) { | |
272 // Is the alloc in the current alloc buffer? | |
273 if (to_space_alloc_buffer()->contains(obj)) { | |
274 assert(to_space_alloc_buffer()->contains(obj + word_sz - 1), | |
275 "Should contain whole object."); | |
276 to_space_alloc_buffer()->undo_allocation(obj, word_sz); | |
277 } else { | |
481
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278 CollectedHeap::fill_with_object(obj, word_sz); |
0 | 279 } |
280 } | |
281 | |
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282 void ParScanThreadState::print_and_clear_promotion_failure_size() { |
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283 if (_promotion_failure_size != 0) { |
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284 if (PrintPromotionFailure) { |
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285 gclog_or_tty->print(" (%d: promotion failure size = " SIZE_FORMAT ") ", |
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286 _thread_num, _promotion_failure_size); |
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287 } |
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288 _promotion_failure_size = 0; |
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289 } |
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290 } |
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291 |
0 | 292 class ParScanThreadStateSet: private ResourceArray { |
293 public: | |
294 // Initializes states for the specified number of threads; | |
295 ParScanThreadStateSet(int num_threads, | |
296 Space& to_space, | |
297 ParNewGeneration& gen, | |
298 Generation& old_gen, | |
299 ObjToScanQueueSet& queue_set, | |
6197 | 300 Stack<oop, mtGC>* overflow_stacks_, |
0 | 301 size_t desired_plab_sz, |
302 ParallelTaskTerminator& term); | |
1710 | 303 |
304 ~ParScanThreadStateSet() { TASKQUEUE_STATS_ONLY(reset_stats()); } | |
305 | |
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306 inline ParScanThreadState& thread_state(int i); |
1710 | 307 |
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308 void reset(int active_workers, bool promotion_failed); |
0 | 309 void flush(); |
1710 | 310 |
311 #if TASKQUEUE_STATS | |
312 static void | |
313 print_termination_stats_hdr(outputStream* const st = gclog_or_tty); | |
314 void print_termination_stats(outputStream* const st = gclog_or_tty); | |
315 static void | |
316 print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); | |
317 void print_taskqueue_stats(outputStream* const st = gclog_or_tty); | |
318 void reset_stats(); | |
319 #endif // TASKQUEUE_STATS | |
320 | |
0 | 321 private: |
322 ParallelTaskTerminator& _term; | |
323 ParNewGeneration& _gen; | |
324 Generation& _next_gen; | |
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325 public: |
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326 bool is_valid(int id) const { return id < length(); } |
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327 ParallelTaskTerminator* terminator() { return &_term; } |
0 | 328 }; |
329 | |
330 | |
331 ParScanThreadStateSet::ParScanThreadStateSet( | |
332 int num_threads, Space& to_space, ParNewGeneration& gen, | |
333 Generation& old_gen, ObjToScanQueueSet& queue_set, | |
6197 | 334 Stack<oop, mtGC>* overflow_stacks, |
0 | 335 size_t desired_plab_sz, ParallelTaskTerminator& term) |
336 : ResourceArray(sizeof(ParScanThreadState), num_threads), | |
1710 | 337 _gen(gen), _next_gen(old_gen), _term(term) |
0 | 338 { |
339 assert(num_threads > 0, "sanity check!"); | |
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340 assert(ParGCUseLocalOverflow == (overflow_stacks != NULL), |
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341 "overflow_stack allocation mismatch"); |
0 | 342 // Initialize states. |
343 for (int i = 0; i < num_threads; ++i) { | |
344 new ((ParScanThreadState*)_data + i) | |
345 ParScanThreadState(&to_space, &gen, &old_gen, i, &queue_set, | |
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346 overflow_stacks, desired_plab_sz, term); |
0 | 347 } |
348 } | |
349 | |
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350 inline ParScanThreadState& ParScanThreadStateSet::thread_state(int i) |
0 | 351 { |
352 assert(i >= 0 && i < length(), "sanity check!"); | |
353 return ((ParScanThreadState*)_data)[i]; | |
354 } | |
355 | |
356 | |
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357 void ParScanThreadStateSet::reset(int active_threads, bool promotion_failed) |
0 | 358 { |
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359 _term.reset_for_reuse(active_threads); |
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360 if (promotion_failed) { |
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361 for (int i = 0; i < length(); ++i) { |
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362 thread_state(i).print_and_clear_promotion_failure_size(); |
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363 } |
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364 } |
0 | 365 } |
366 | |
1710 | 367 #if TASKQUEUE_STATS |
368 void | |
369 ParScanThreadState::reset_stats() | |
370 { | |
371 taskqueue_stats().reset(); | |
372 _term_attempts = 0; | |
373 _overflow_refills = 0; | |
374 _overflow_refill_objs = 0; | |
375 } | |
376 | |
377 void ParScanThreadStateSet::reset_stats() | |
378 { | |
379 for (int i = 0; i < length(); ++i) { | |
380 thread_state(i).reset_stats(); | |
381 } | |
382 } | |
383 | |
384 void | |
385 ParScanThreadStateSet::print_termination_stats_hdr(outputStream* const st) | |
386 { | |
387 st->print_raw_cr("GC Termination Stats"); | |
388 st->print_raw_cr(" elapsed --strong roots-- " | |
389 "-------termination-------"); | |
390 st->print_raw_cr("thr ms ms % " | |
391 " ms % attempts"); | |
392 st->print_raw_cr("--- --------- --------- ------ " | |
393 "--------- ------ --------"); | |
394 } | |
395 | |
396 void ParScanThreadStateSet::print_termination_stats(outputStream* const st) | |
397 { | |
398 print_termination_stats_hdr(st); | |
399 | |
400 for (int i = 0; i < length(); ++i) { | |
401 const ParScanThreadState & pss = thread_state(i); | |
402 const double elapsed_ms = pss.elapsed_time() * 1000.0; | |
403 const double s_roots_ms = pss.strong_roots_time() * 1000.0; | |
404 const double term_ms = pss.term_time() * 1000.0; | |
405 st->print_cr("%3d %9.2f %9.2f %6.2f " | |
406 "%9.2f %6.2f " SIZE_FORMAT_W(8), | |
407 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms, | |
408 term_ms, term_ms * 100 / elapsed_ms, pss.term_attempts()); | |
409 } | |
410 } | |
411 | |
412 // Print stats related to work queue activity. | |
413 void ParScanThreadStateSet::print_taskqueue_stats_hdr(outputStream* const st) | |
414 { | |
415 st->print_raw_cr("GC Task Stats"); | |
416 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); | |
417 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); | |
418 } | |
419 | |
420 void ParScanThreadStateSet::print_taskqueue_stats(outputStream* const st) | |
421 { | |
422 print_taskqueue_stats_hdr(st); | |
423 | |
424 TaskQueueStats totals; | |
425 for (int i = 0; i < length(); ++i) { | |
426 const ParScanThreadState & pss = thread_state(i); | |
427 const TaskQueueStats & stats = pss.taskqueue_stats(); | |
428 st->print("%3d ", i); stats.print(st); st->cr(); | |
429 totals += stats; | |
430 | |
431 if (pss.overflow_refills() > 0) { | |
432 st->print_cr(" " SIZE_FORMAT_W(10) " overflow refills " | |
433 SIZE_FORMAT_W(10) " overflow objects", | |
434 pss.overflow_refills(), pss.overflow_refill_objs()); | |
435 } | |
436 } | |
437 st->print("tot "); totals.print(st); st->cr(); | |
438 | |
439 DEBUG_ONLY(totals.verify()); | |
440 } | |
441 #endif // TASKQUEUE_STATS | |
442 | |
0 | 443 void ParScanThreadStateSet::flush() |
444 { | |
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445 // Work in this loop should be kept as lightweight as |
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446 // possible since this might otherwise become a bottleneck |
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447 // to scaling. Should we add heavy-weight work into this |
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448 // loop, consider parallelizing the loop into the worker threads. |
0 | 449 for (int i = 0; i < length(); ++i) { |
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450 ParScanThreadState& par_scan_state = thread_state(i); |
0 | 451 |
452 // Flush stats related to To-space PLAB activity and | |
453 // retire the last buffer. | |
454 par_scan_state.to_space_alloc_buffer()-> | |
455 flush_stats_and_retire(_gen.plab_stats(), | |
6595 | 456 true /* end_of_gc */, |
457 false /* retain */); | |
0 | 458 |
459 // Every thread has its own age table. We need to merge | |
460 // them all into one. | |
461 ageTable *local_table = par_scan_state.age_table(); | |
462 _gen.age_table()->merge(local_table); | |
463 | |
464 // Inform old gen that we're done. | |
465 _next_gen.par_promote_alloc_done(i); | |
466 _next_gen.par_oop_since_save_marks_iterate_done(i); | |
1710 | 467 } |
0 | 468 |
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469 if (UseConcMarkSweepGC && ParallelGCThreads > 0) { |
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470 // We need to call this even when ResizeOldPLAB is disabled |
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471 // so as to avoid breaking some asserts. While we may be able |
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472 // to avoid this by reorganizing the code a bit, I am loathe |
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473 // to do that unless we find cases where ergo leads to bad |
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474 // performance. |
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475 CFLS_LAB::compute_desired_plab_size(); |
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476 } |
0 | 477 } |
478 | |
479 ParScanClosure::ParScanClosure(ParNewGeneration* g, | |
480 ParScanThreadState* par_scan_state) : | |
481 OopsInGenClosure(g), _par_scan_state(par_scan_state), _g(g) | |
482 { | |
483 assert(_g->level() == 0, "Optimized for youngest generation"); | |
484 _boundary = _g->reserved().end(); | |
485 } | |
486 | |
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487 void ParScanWithBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, true, false); } |
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488 void ParScanWithBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, true, false); } |
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489 |
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490 void ParScanWithoutBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, false, false); } |
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491 void ParScanWithoutBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, false, false); } |
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492 |
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493 void ParRootScanWithBarrierTwoGensClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, true, true); } |
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494 void ParRootScanWithBarrierTwoGensClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, true, true); } |
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495 |
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496 void ParRootScanWithoutBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, false, true); } |
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497 void ParRootScanWithoutBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, false, true); } |
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498 |
0 | 499 ParScanWeakRefClosure::ParScanWeakRefClosure(ParNewGeneration* g, |
500 ParScanThreadState* par_scan_state) | |
501 : ScanWeakRefClosure(g), _par_scan_state(par_scan_state) | |
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502 {} |
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503 |
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504 void ParScanWeakRefClosure::do_oop(oop* p) { ParScanWeakRefClosure::do_oop_work(p); } |
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505 void ParScanWeakRefClosure::do_oop(narrowOop* p) { ParScanWeakRefClosure::do_oop_work(p); } |
0 | 506 |
507 #ifdef WIN32 | |
508 #pragma warning(disable: 4786) /* identifier was truncated to '255' characters in the browser information */ | |
509 #endif | |
510 | |
511 ParEvacuateFollowersClosure::ParEvacuateFollowersClosure( | |
512 ParScanThreadState* par_scan_state_, | |
513 ParScanWithoutBarrierClosure* to_space_closure_, | |
514 ParScanWithBarrierClosure* old_gen_closure_, | |
515 ParRootScanWithoutBarrierClosure* to_space_root_closure_, | |
516 ParNewGeneration* par_gen_, | |
517 ParRootScanWithBarrierTwoGensClosure* old_gen_root_closure_, | |
518 ObjToScanQueueSet* task_queues_, | |
519 ParallelTaskTerminator* terminator_) : | |
520 | |
521 _par_scan_state(par_scan_state_), | |
522 _to_space_closure(to_space_closure_), | |
523 _old_gen_closure(old_gen_closure_), | |
524 _to_space_root_closure(to_space_root_closure_), | |
525 _old_gen_root_closure(old_gen_root_closure_), | |
526 _par_gen(par_gen_), | |
527 _task_queues(task_queues_), | |
528 _terminator(terminator_) | |
529 {} | |
530 | |
531 void ParEvacuateFollowersClosure::do_void() { | |
532 ObjToScanQueue* work_q = par_scan_state()->work_queue(); | |
533 | |
534 while (true) { | |
535 | |
536 // Scan to-space and old-gen objs until we run out of both. | |
537 oop obj_to_scan; | |
538 par_scan_state()->trim_queues(0); | |
539 | |
540 // We have no local work, attempt to steal from other threads. | |
541 | |
542 // attempt to steal work from promoted. | |
543 if (task_queues()->steal(par_scan_state()->thread_num(), | |
544 par_scan_state()->hash_seed(), | |
545 obj_to_scan)) { | |
546 bool res = work_q->push(obj_to_scan); | |
547 assert(res, "Empty queue should have room for a push."); | |
548 | |
549 // if successful, goto Start. | |
550 continue; | |
551 | |
552 // try global overflow list. | |
553 } else if (par_gen()->take_from_overflow_list(par_scan_state())) { | |
554 continue; | |
555 } | |
556 | |
557 // Otherwise, offer termination. | |
558 par_scan_state()->start_term_time(); | |
559 if (terminator()->offer_termination()) break; | |
560 par_scan_state()->end_term_time(); | |
561 } | |
534 | 562 assert(par_gen()->_overflow_list == NULL && par_gen()->_num_par_pushes == 0, |
563 "Broken overflow list?"); | |
0 | 564 // Finish the last termination pause. |
565 par_scan_state()->end_term_time(); | |
566 } | |
567 | |
568 ParNewGenTask::ParNewGenTask(ParNewGeneration* gen, Generation* next_gen, | |
569 HeapWord* young_old_boundary, ParScanThreadStateSet* state_set) : | |
570 AbstractGangTask("ParNewGeneration collection"), | |
571 _gen(gen), _next_gen(next_gen), | |
572 _young_old_boundary(young_old_boundary), | |
573 _state_set(state_set) | |
574 {} | |
575 | |
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576 // Reset the terminator for the given number of |
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577 // active threads. |
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578 void ParNewGenTask::set_for_termination(int active_workers) { |
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579 _state_set->reset(active_workers, _gen->promotion_failed()); |
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580 // Should the heap be passed in? There's only 1 for now so |
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581 // grab it instead. |
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582 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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583 gch->set_n_termination(active_workers); |
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584 } |
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585 |
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586 // The "i" passed to this method is the part of the work for |
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587 // this thread. It is not the worker ID. The "i" is derived |
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588 // from _started_workers which is incremented in internal_note_start() |
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589 // called in GangWorker loop() and which is called under the |
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590 // which is called under the protection of the gang monitor and is |
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591 // called after a task is started. So "i" is based on |
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592 // first-come-first-served. |
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593 |
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594 void ParNewGenTask::work(uint worker_id) { |
0 | 595 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
596 // Since this is being done in a separate thread, need new resource | |
597 // and handle marks. | |
598 ResourceMark rm; | |
599 HandleMark hm; | |
600 // We would need multiple old-gen queues otherwise. | |
679
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601 assert(gch->n_gens() == 2, "Par young collection currently only works with one older gen."); |
0 | 602 |
603 Generation* old_gen = gch->next_gen(_gen); | |
604 | |
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605 ParScanThreadState& par_scan_state = _state_set->thread_state(worker_id); |
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606 assert(_state_set->is_valid(worker_id), "Should not have been called"); |
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607 |
0 | 608 par_scan_state.set_young_old_boundary(_young_old_boundary); |
609 | |
610 par_scan_state.start_strong_roots(); | |
611 gch->gen_process_strong_roots(_gen->level(), | |
989
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612 true, // Process younger gens, if any, |
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613 // as strong roots. |
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614 false, // no scope; this is parallel code |
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615 false, // not collecting perm generation. |
0 | 616 SharedHeap::SO_AllClasses, |
989
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617 &par_scan_state.to_space_root_closure(), |
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618 true, // walk *all* scavengable nmethods |
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619 &par_scan_state.older_gen_closure()); |
0 | 620 par_scan_state.end_strong_roots(); |
621 | |
622 // "evacuate followers". | |
623 par_scan_state.evacuate_followers_closure().do_void(); | |
624 } | |
625 | |
626 #ifdef _MSC_VER | |
627 #pragma warning( push ) | |
628 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list | |
629 #endif | |
630 ParNewGeneration:: | |
631 ParNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level) | |
632 : DefNewGeneration(rs, initial_byte_size, level, "PCopy"), | |
633 _overflow_list(NULL), | |
634 _is_alive_closure(this), | |
635 _plab_stats(YoungPLABSize, PLABWeight) | |
636 { | |
534 | 637 NOT_PRODUCT(_overflow_counter = ParGCWorkQueueOverflowInterval;) |
638 NOT_PRODUCT(_num_par_pushes = 0;) | |
0 | 639 _task_queues = new ObjToScanQueueSet(ParallelGCThreads); |
640 guarantee(_task_queues != NULL, "task_queues allocation failure."); | |
641 | |
642 for (uint i1 = 0; i1 < ParallelGCThreads; i1++) { | |
1665 | 643 ObjToScanQueue *q = new ObjToScanQueue(); |
644 guarantee(q != NULL, "work_queue Allocation failure."); | |
645 _task_queues->register_queue(i1, q); | |
0 | 646 } |
647 | |
648 for (uint i2 = 0; i2 < ParallelGCThreads; i2++) | |
649 _task_queues->queue(i2)->initialize(); | |
650 | |
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651 _overflow_stacks = NULL; |
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652 if (ParGCUseLocalOverflow) { |
6197 | 653 |
654 // typedef to workaround NEW_C_HEAP_ARRAY macro, which can not deal | |
655 // with ',' | |
656 typedef Stack<oop, mtGC> GCOopStack; | |
657 | |
658 _overflow_stacks = NEW_C_HEAP_ARRAY(GCOopStack, ParallelGCThreads, mtGC); | |
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659 for (size_t i = 0; i < ParallelGCThreads; ++i) { |
6197 | 660 new (_overflow_stacks + i) Stack<oop, mtGC>(); |
695 | 661 } |
662 } | |
663 | |
0 | 664 if (UsePerfData) { |
665 EXCEPTION_MARK; | |
666 ResourceMark rm; | |
667 | |
668 const char* cname = | |
669 PerfDataManager::counter_name(_gen_counters->name_space(), "threads"); | |
670 PerfDataManager::create_constant(SUN_GC, cname, PerfData::U_None, | |
671 ParallelGCThreads, CHECK); | |
672 } | |
673 } | |
674 #ifdef _MSC_VER | |
675 #pragma warning( pop ) | |
676 #endif | |
677 | |
678 // ParNewGeneration:: | |
679 ParKeepAliveClosure::ParKeepAliveClosure(ParScanWeakRefClosure* cl) : | |
680 DefNewGeneration::KeepAliveClosure(cl), _par_cl(cl) {} | |
681 | |
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682 template <class T> |
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683 void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop_work(T* p) { |
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684 #ifdef ASSERT |
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685 { |
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686 assert(!oopDesc::is_null(*p), "expected non-null ref"); |
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687 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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688 // We never expect to see a null reference being processed |
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689 // as a weak reference. |
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690 assert(obj->is_oop(), "expected an oop while scanning weak refs"); |
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691 } |
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692 #endif // ASSERT |
0 | 693 |
694 _par_cl->do_oop_nv(p); | |
695 | |
696 if (Universe::heap()->is_in_reserved(p)) { | |
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697 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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698 _rs->write_ref_field_gc_par(p, obj); |
0 | 699 } |
700 } | |
701 | |
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702 void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop(oop* p) { ParKeepAliveClosure::do_oop_work(p); } |
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703 void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop(narrowOop* p) { ParKeepAliveClosure::do_oop_work(p); } |
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704 |
0 | 705 // ParNewGeneration:: |
706 KeepAliveClosure::KeepAliveClosure(ScanWeakRefClosure* cl) : | |
707 DefNewGeneration::KeepAliveClosure(cl) {} | |
708 | |
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709 template <class T> |
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710 void /*ParNewGeneration::*/KeepAliveClosure::do_oop_work(T* p) { |
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711 #ifdef ASSERT |
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712 { |
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713 assert(!oopDesc::is_null(*p), "expected non-null ref"); |
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714 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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715 // We never expect to see a null reference being processed |
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716 // as a weak reference. |
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717 assert(obj->is_oop(), "expected an oop while scanning weak refs"); |
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718 } |
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719 #endif // ASSERT |
0 | 720 |
721 _cl->do_oop_nv(p); | |
722 | |
723 if (Universe::heap()->is_in_reserved(p)) { | |
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724 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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725 _rs->write_ref_field_gc_par(p, obj); |
0 | 726 } |
727 } | |
728 | |
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729 void /*ParNewGeneration::*/KeepAliveClosure::do_oop(oop* p) { KeepAliveClosure::do_oop_work(p); } |
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730 void /*ParNewGeneration::*/KeepAliveClosure::do_oop(narrowOop* p) { KeepAliveClosure::do_oop_work(p); } |
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731 |
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732 template <class T> void ScanClosureWithParBarrier::do_oop_work(T* p) { |
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733 T heap_oop = oopDesc::load_heap_oop(p); |
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734 if (!oopDesc::is_null(heap_oop)) { |
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735 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); |
0 | 736 if ((HeapWord*)obj < _boundary) { |
737 assert(!_g->to()->is_in_reserved(obj), "Scanning field twice?"); | |
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738 oop new_obj = obj->is_forwarded() |
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739 ? obj->forwardee() |
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740 : _g->DefNewGeneration::copy_to_survivor_space(obj); |
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741 oopDesc::encode_store_heap_oop_not_null(p, new_obj); |
0 | 742 } |
743 if (_gc_barrier) { | |
744 // If p points to a younger generation, mark the card. | |
745 if ((HeapWord*)obj < _gen_boundary) { | |
746 _rs->write_ref_field_gc_par(p, obj); | |
747 } | |
748 } | |
749 } | |
750 } | |
751 | |
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752 void ScanClosureWithParBarrier::do_oop(oop* p) { ScanClosureWithParBarrier::do_oop_work(p); } |
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753 void ScanClosureWithParBarrier::do_oop(narrowOop* p) { ScanClosureWithParBarrier::do_oop_work(p); } |
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754 |
0 | 755 class ParNewRefProcTaskProxy: public AbstractGangTask { |
756 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; | |
757 public: | |
758 ParNewRefProcTaskProxy(ProcessTask& task, ParNewGeneration& gen, | |
759 Generation& next_gen, | |
760 HeapWord* young_old_boundary, | |
761 ParScanThreadStateSet& state_set); | |
762 | |
763 private: | |
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764 virtual void work(uint worker_id); |
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765 virtual void set_for_termination(int active_workers) { |
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766 _state_set.terminator()->reset_for_reuse(active_workers); |
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767 } |
0 | 768 private: |
769 ParNewGeneration& _gen; | |
770 ProcessTask& _task; | |
771 Generation& _next_gen; | |
772 HeapWord* _young_old_boundary; | |
773 ParScanThreadStateSet& _state_set; | |
774 }; | |
775 | |
776 ParNewRefProcTaskProxy::ParNewRefProcTaskProxy( | |
777 ProcessTask& task, ParNewGeneration& gen, | |
778 Generation& next_gen, | |
779 HeapWord* young_old_boundary, | |
780 ParScanThreadStateSet& state_set) | |
781 : AbstractGangTask("ParNewGeneration parallel reference processing"), | |
782 _gen(gen), | |
783 _task(task), | |
784 _next_gen(next_gen), | |
785 _young_old_boundary(young_old_boundary), | |
786 _state_set(state_set) | |
787 { | |
788 } | |
789 | |
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790 void ParNewRefProcTaskProxy::work(uint worker_id) |
0 | 791 { |
792 ResourceMark rm; | |
793 HandleMark hm; | |
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794 ParScanThreadState& par_scan_state = _state_set.thread_state(worker_id); |
0 | 795 par_scan_state.set_young_old_boundary(_young_old_boundary); |
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796 _task.work(worker_id, par_scan_state.is_alive_closure(), |
0 | 797 par_scan_state.keep_alive_closure(), |
798 par_scan_state.evacuate_followers_closure()); | |
799 } | |
800 | |
801 class ParNewRefEnqueueTaskProxy: public AbstractGangTask { | |
802 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; | |
803 EnqueueTask& _task; | |
804 | |
805 public: | |
806 ParNewRefEnqueueTaskProxy(EnqueueTask& task) | |
807 : AbstractGangTask("ParNewGeneration parallel reference enqueue"), | |
808 _task(task) | |
809 { } | |
810 | |
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811 virtual void work(uint worker_id) |
0 | 812 { |
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813 _task.work(worker_id); |
0 | 814 } |
815 }; | |
816 | |
817 | |
818 void ParNewRefProcTaskExecutor::execute(ProcessTask& task) | |
819 { | |
820 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
821 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
822 "not a generational heap"); | |
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823 FlexibleWorkGang* workers = gch->workers(); |
0 | 824 assert(workers != NULL, "Need parallel worker threads."); |
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825 _state_set.reset(workers->active_workers(), _generation.promotion_failed()); |
0 | 826 ParNewRefProcTaskProxy rp_task(task, _generation, *_generation.next_gen(), |
827 _generation.reserved().end(), _state_set); | |
828 workers->run_task(&rp_task); | |
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829 _state_set.reset(0 /* bad value in debug if not reset */, |
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830 _generation.promotion_failed()); |
0 | 831 } |
832 | |
833 void ParNewRefProcTaskExecutor::execute(EnqueueTask& task) | |
834 { | |
835 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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836 FlexibleWorkGang* workers = gch->workers(); |
0 | 837 assert(workers != NULL, "Need parallel worker threads."); |
838 ParNewRefEnqueueTaskProxy enq_task(task); | |
839 workers->run_task(&enq_task); | |
840 } | |
841 | |
842 void ParNewRefProcTaskExecutor::set_single_threaded_mode() | |
843 { | |
844 _state_set.flush(); | |
845 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
846 gch->set_par_threads(0); // 0 ==> non-parallel. | |
847 gch->save_marks(); | |
848 } | |
849 | |
850 ScanClosureWithParBarrier:: | |
851 ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier) : | |
852 ScanClosure(g, gc_barrier) {} | |
853 | |
854 EvacuateFollowersClosureGeneral:: | |
855 EvacuateFollowersClosureGeneral(GenCollectedHeap* gch, int level, | |
856 OopsInGenClosure* cur, | |
857 OopsInGenClosure* older) : | |
858 _gch(gch), _level(level), | |
859 _scan_cur_or_nonheap(cur), _scan_older(older) | |
860 {} | |
861 | |
862 void EvacuateFollowersClosureGeneral::do_void() { | |
863 do { | |
864 // Beware: this call will lead to closure applications via virtual | |
865 // calls. | |
866 _gch->oop_since_save_marks_iterate(_level, | |
867 _scan_cur_or_nonheap, | |
868 _scan_older); | |
869 } while (!_gch->no_allocs_since_save_marks(_level)); | |
870 } | |
871 | |
872 | |
873 bool ParNewGeneration::_avoid_promotion_undo = false; | |
874 | |
875 void ParNewGeneration::adjust_desired_tenuring_threshold() { | |
876 // Set the desired survivor size to half the real survivor space | |
877 _tenuring_threshold = | |
878 age_table()->compute_tenuring_threshold(to()->capacity()/HeapWordSize); | |
879 } | |
880 | |
881 // A Generation that does parallel young-gen collection. | |
882 | |
883 void ParNewGeneration::collect(bool full, | |
884 bool clear_all_soft_refs, | |
885 size_t size, | |
886 bool is_tlab) { | |
887 assert(full || size > 0, "otherwise we don't want to collect"); | |
888 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
889 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
890 "not a CMS generational heap"); | |
891 AdaptiveSizePolicy* size_policy = gch->gen_policy()->size_policy(); | |
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892 FlexibleWorkGang* workers = gch->workers(); |
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893 assert(workers != NULL, "Need workgang for parallel work"); |
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894 int active_workers = |
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895 AdaptiveSizePolicy::calc_active_workers(workers->total_workers(), |
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896 workers->active_workers(), |
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897 Threads::number_of_non_daemon_threads()); |
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898 workers->set_active_workers(active_workers); |
0 | 899 _next_gen = gch->next_gen(this); |
900 assert(_next_gen != NULL, | |
901 "This must be the youngest gen, and not the only gen"); | |
902 assert(gch->n_gens() == 2, | |
903 "Par collection currently only works with single older gen."); | |
904 // Do we have to avoid promotion_undo? | |
905 if (gch->collector_policy()->is_concurrent_mark_sweep_policy()) { | |
906 set_avoid_promotion_undo(true); | |
907 } | |
908 | |
909 // If the next generation is too full to accomodate worst-case promotion | |
910 // from this generation, pass on collection; let the next generation | |
911 // do it. | |
912 if (!collection_attempt_is_safe()) { | |
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913 gch->set_incremental_collection_failed(); // slight lie, in that we did not even attempt one |
0 | 914 return; |
915 } | |
916 assert(to()->is_empty(), "Else not collection_attempt_is_safe"); | |
917 | |
918 init_assuming_no_promotion_failure(); | |
919 | |
920 if (UseAdaptiveSizePolicy) { | |
921 set_survivor_overflow(false); | |
922 size_policy->minor_collection_begin(); | |
923 } | |
924 | |
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925 TraceTime t1(GCCauseString("GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, gclog_or_tty); |
0 | 926 // Capture heap used before collection (for printing). |
927 size_t gch_prev_used = gch->used(); | |
928 | |
929 SpecializationStats::clear(); | |
930 | |
931 age_table()->clear(); | |
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932 to()->clear(SpaceDecorator::Mangle); |
0 | 933 |
934 gch->save_marks(); | |
935 assert(workers != NULL, "Need parallel worker threads."); | |
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936 int n_workers = active_workers; |
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937 |
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938 // Set the correct parallelism (number of queues) in the reference processor |
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939 ref_processor()->set_active_mt_degree(n_workers); |
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940 |
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941 // Always set the terminator for the active number of workers |
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942 // because only those workers go through the termination protocol. |
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943 ParallelTaskTerminator _term(n_workers, task_queues()); |
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944 ParScanThreadStateSet thread_state_set(workers->active_workers(), |
0 | 945 *to(), *this, *_next_gen, *task_queues(), |
695 | 946 _overflow_stacks, desired_plab_sz(), _term); |
0 | 947 |
948 ParNewGenTask tsk(this, _next_gen, reserved().end(), &thread_state_set); | |
949 gch->set_par_threads(n_workers); | |
950 gch->rem_set()->prepare_for_younger_refs_iterate(true); | |
951 // It turns out that even when we're using 1 thread, doing the work in a | |
952 // separate thread causes wide variance in run times. We can't help this | |
953 // in the multi-threaded case, but we special-case n=1 here to get | |
954 // repeatable measurements of the 1-thread overhead of the parallel code. | |
955 if (n_workers > 1) { | |
989
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956 GenCollectedHeap::StrongRootsScope srs(gch); |
0 | 957 workers->run_task(&tsk); |
958 } else { | |
989
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959 GenCollectedHeap::StrongRootsScope srs(gch); |
0 | 960 tsk.work(0); |
961 } | |
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962 thread_state_set.reset(0 /* Bad value in debug if not reset */, |
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963 promotion_failed()); |
0 | 964 |
965 // Process (weak) reference objects found during scavenge. | |
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966 ReferenceProcessor* rp = ref_processor(); |
0 | 967 IsAliveClosure is_alive(this); |
968 ScanWeakRefClosure scan_weak_ref(this); | |
969 KeepAliveClosure keep_alive(&scan_weak_ref); | |
970 ScanClosure scan_without_gc_barrier(this, false); | |
971 ScanClosureWithParBarrier scan_with_gc_barrier(this, true); | |
972 set_promo_failure_scan_stack_closure(&scan_without_gc_barrier); | |
973 EvacuateFollowersClosureGeneral evacuate_followers(gch, _level, | |
974 &scan_without_gc_barrier, &scan_with_gc_barrier); | |
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975 rp->setup_policy(clear_all_soft_refs); |
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976 // Can the mt_degree be set later (at run_task() time would be best)? |
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977 rp->set_active_mt_degree(active_workers); |
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978 if (rp->processing_is_mt()) { |
0 | 979 ParNewRefProcTaskExecutor task_executor(*this, thread_state_set); |
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980 rp->process_discovered_references(&is_alive, &keep_alive, |
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981 &evacuate_followers, &task_executor); |
0 | 982 } else { |
983 thread_state_set.flush(); | |
984 gch->set_par_threads(0); // 0 ==> non-parallel. | |
985 gch->save_marks(); | |
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986 rp->process_discovered_references(&is_alive, &keep_alive, |
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987 &evacuate_followers, NULL); |
0 | 988 } |
989 if (!promotion_failed()) { | |
990 // Swap the survivor spaces. | |
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991 eden()->clear(SpaceDecorator::Mangle); |
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992 from()->clear(SpaceDecorator::Mangle); |
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993 if (ZapUnusedHeapArea) { |
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994 // This is now done here because of the piece-meal mangling which |
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995 // can check for valid mangling at intermediate points in the |
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996 // collection(s). When a minor collection fails to collect |
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997 // sufficient space resizing of the young generation can occur |
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998 // an redistribute the spaces in the young generation. Mangle |
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999 // here so that unzapped regions don't get distributed to |
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1000 // other spaces. |
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1001 to()->mangle_unused_area(); |
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1002 } |
0 | 1003 swap_spaces(); |
1004 | |
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1005 // A successful scavenge should restart the GC time limit count which is |
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1006 // for full GC's. |
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1007 size_policy->reset_gc_overhead_limit_count(); |
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1008 |
0 | 1009 assert(to()->is_empty(), "to space should be empty now"); |
1010 } else { | |
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1011 assert(_promo_failure_scan_stack.is_empty(), "post condition"); |
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1012 _promo_failure_scan_stack.clear(true); // Clear cached segments. |
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1013 |
0 | 1014 remove_forwarding_pointers(); |
1015 if (PrintGCDetails) { | |
1016 gclog_or_tty->print(" (promotion failed)"); | |
1017 } | |
1018 // All the spaces are in play for mark-sweep. | |
1019 swap_spaces(); // Make life simpler for CMS || rescan; see 6483690. | |
1020 from()->set_next_compaction_space(to()); | |
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1021 gch->set_incremental_collection_failed(); |
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1022 // Inform the next generation that a promotion failure occurred. |
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1023 _next_gen->promotion_failure_occurred(); |
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1024 |
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1025 // Reset the PromotionFailureALot counters. |
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1026 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();) |
0 | 1027 } |
1028 // set new iteration safe limit for the survivor spaces | |
1029 from()->set_concurrent_iteration_safe_limit(from()->top()); | |
1030 to()->set_concurrent_iteration_safe_limit(to()->top()); | |
1031 | |
1032 adjust_desired_tenuring_threshold(); | |
1033 if (ResizePLAB) { | |
1034 plab_stats()->adjust_desired_plab_sz(); | |
1035 } | |
1036 | |
1037 if (PrintGC && !PrintGCDetails) { | |
1038 gch->print_heap_change(gch_prev_used); | |
1039 } | |
1040 | |
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1041 if (PrintGCDetails && ParallelGCVerbose) { |
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1042 TASKQUEUE_STATS_ONLY(thread_state_set.print_termination_stats()); |
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1043 TASKQUEUE_STATS_ONLY(thread_state_set.print_taskqueue_stats()); |
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1044 } |
1710 | 1045 |
0 | 1046 if (UseAdaptiveSizePolicy) { |
1047 size_policy->minor_collection_end(gch->gc_cause()); | |
1048 size_policy->avg_survived()->sample(from()->used()); | |
1049 } | |
1050 | |
4911 | 1051 // We need to use a monotonically non-deccreasing time in ms |
1052 // or we will see time-warp warnings and os::javaTimeMillis() | |
1053 // does not guarantee monotonicity. | |
1054 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; | |
1055 update_time_of_last_gc(now); | |
0 | 1056 |
1057 SpecializationStats::print(); | |
1058 | |
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1059 rp->set_enqueuing_is_done(true); |
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1060 if (rp->processing_is_mt()) { |
0 | 1061 ParNewRefProcTaskExecutor task_executor(*this, thread_state_set); |
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1062 rp->enqueue_discovered_references(&task_executor); |
0 | 1063 } else { |
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1064 rp->enqueue_discovered_references(NULL); |
0 | 1065 } |
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1066 rp->verify_no_references_recorded(); |
0 | 1067 } |
1068 | |
1069 static int sum; | |
1070 void ParNewGeneration::waste_some_time() { | |
1071 for (int i = 0; i < 100; i++) { | |
1072 sum += i; | |
1073 } | |
1074 } | |
1075 | |
1076 static const oop ClaimedForwardPtr = oop(0x4); | |
1077 | |
1078 // Because of concurrency, there are times where an object for which | |
1079 // "is_forwarded()" is true contains an "interim" forwarding pointer | |
1080 // value. Such a value will soon be overwritten with a real value. | |
1081 // This method requires "obj" to have a forwarding pointer, and waits, if | |
1082 // necessary for a real one to be inserted, and returns it. | |
1083 | |
1084 oop ParNewGeneration::real_forwardee(oop obj) { | |
1085 oop forward_ptr = obj->forwardee(); | |
1086 if (forward_ptr != ClaimedForwardPtr) { | |
1087 return forward_ptr; | |
1088 } else { | |
1089 return real_forwardee_slow(obj); | |
1090 } | |
1091 } | |
1092 | |
1093 oop ParNewGeneration::real_forwardee_slow(oop obj) { | |
1094 // Spin-read if it is claimed but not yet written by another thread. | |
1095 oop forward_ptr = obj->forwardee(); | |
1096 while (forward_ptr == ClaimedForwardPtr) { | |
1097 waste_some_time(); | |
1098 assert(obj->is_forwarded(), "precondition"); | |
1099 forward_ptr = obj->forwardee(); | |
1100 } | |
1101 return forward_ptr; | |
1102 } | |
1103 | |
1104 #ifdef ASSERT | |
1105 bool ParNewGeneration::is_legal_forward_ptr(oop p) { | |
1106 return | |
1107 (_avoid_promotion_undo && p == ClaimedForwardPtr) | |
1108 || Universe::heap()->is_in_reserved(p); | |
1109 } | |
1110 #endif | |
1111 | |
1112 void ParNewGeneration::preserve_mark_if_necessary(oop obj, markOop m) { | |
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1113 if (m->must_be_preserved_for_promotion_failure(obj)) { |
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1114 // We should really have separate per-worker stacks, rather |
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1115 // than use locking of a common pair of stacks. |
0 | 1116 MutexLocker ml(ParGCRareEvent_lock); |
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1117 preserve_mark(obj, m); |
0 | 1118 } |
1119 } | |
1120 | |
1121 // Multiple GC threads may try to promote an object. If the object | |
1122 // is successfully promoted, a forwarding pointer will be installed in | |
1123 // the object in the young generation. This method claims the right | |
1124 // to install the forwarding pointer before it copies the object, | |
1125 // thus avoiding the need to undo the copy as in | |
1126 // copy_to_survivor_space_avoiding_with_undo. | |
1127 | |
1128 oop ParNewGeneration::copy_to_survivor_space_avoiding_promotion_undo( | |
1129 ParScanThreadState* par_scan_state, oop old, size_t sz, markOop m) { | |
1130 // In the sequential version, this assert also says that the object is | |
1131 // not forwarded. That might not be the case here. It is the case that | |
1132 // the caller observed it to be not forwarded at some time in the past. | |
1133 assert(is_in_reserved(old), "shouldn't be scavenging this oop"); | |
1134 | |
1135 // The sequential code read "old->age()" below. That doesn't work here, | |
1136 // since the age is in the mark word, and that might be overwritten with | |
1137 // a forwarding pointer by a parallel thread. So we must save the mark | |
1138 // word in a local and then analyze it. | |
1139 oopDesc dummyOld; | |
1140 dummyOld.set_mark(m); | |
1141 assert(!dummyOld.is_forwarded(), | |
1142 "should not be called with forwarding pointer mark word."); | |
1143 | |
1144 oop new_obj = NULL; | |
1145 oop forward_ptr; | |
1146 | |
1147 // Try allocating obj in to-space (unless too old) | |
1148 if (dummyOld.age() < tenuring_threshold()) { | |
1149 new_obj = (oop)par_scan_state->alloc_in_to_space(sz); | |
1150 if (new_obj == NULL) { | |
1151 set_survivor_overflow(true); | |
1152 } | |
1153 } | |
1154 | |
1155 if (new_obj == NULL) { | |
1156 // Either to-space is full or we decided to promote | |
1157 // try allocating obj tenured | |
1158 | |
1159 // Attempt to install a null forwarding pointer (atomically), | |
1160 // to claim the right to install the real forwarding pointer. | |
1161 forward_ptr = old->forward_to_atomic(ClaimedForwardPtr); | |
1162 if (forward_ptr != NULL) { | |
1163 // someone else beat us to it. | |
1164 return real_forwardee(old); | |
1165 } | |
1166 | |
1167 new_obj = _next_gen->par_promote(par_scan_state->thread_num(), | |
1168 old, m, sz); | |
1169 | |
1170 if (new_obj == NULL) { | |
1171 // promotion failed, forward to self | |
1172 _promotion_failed = true; | |
1173 new_obj = old; | |
1174 | |
1175 preserve_mark_if_necessary(old, m); | |
1145
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1176 // Log the size of the maiden promotion failure |
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1177 par_scan_state->log_promotion_failure(sz); |
0 | 1178 } |
1179 | |
1180 old->forward_to(new_obj); | |
1181 forward_ptr = NULL; | |
1182 } else { | |
1183 // Is in to-space; do copying ourselves. | |
1184 Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)new_obj, sz); | |
1185 forward_ptr = old->forward_to_atomic(new_obj); | |
1186 // Restore the mark word copied above. | |
1187 new_obj->set_mark(m); | |
1188 // Increment age if obj still in new generation | |
1189 new_obj->incr_age(); | |
1190 par_scan_state->age_table()->add(new_obj, sz); | |
1191 } | |
1192 assert(new_obj != NULL, "just checking"); | |
1193 | |
1194 if (forward_ptr == NULL) { | |
1195 oop obj_to_push = new_obj; | |
1196 if (par_scan_state->should_be_partially_scanned(obj_to_push, old)) { | |
1197 // Length field used as index of next element to be scanned. | |
1198 // Real length can be obtained from real_forwardee() | |
1199 arrayOop(old)->set_length(0); | |
1200 obj_to_push = old; | |
1201 assert(obj_to_push->is_forwarded() && obj_to_push->forwardee() != obj_to_push, | |
1202 "push forwarded object"); | |
1203 } | |
1204 // Push it on one of the queues of to-be-scanned objects. | |
534 | 1205 bool simulate_overflow = false; |
1206 NOT_PRODUCT( | |
1207 if (ParGCWorkQueueOverflowALot && should_simulate_overflow()) { | |
1208 // simulate a stack overflow | |
1209 simulate_overflow = true; | |
1210 } | |
1211 ) | |
1212 if (simulate_overflow || !par_scan_state->work_queue()->push(obj_to_push)) { | |
0 | 1213 // Add stats for overflow pushes. |
1214 if (Verbose && PrintGCDetails) { | |
1215 gclog_or_tty->print("queue overflow!\n"); | |
1216 } | |
534 | 1217 push_on_overflow_list(old, par_scan_state); |
1710 | 1218 TASKQUEUE_STATS_ONLY(par_scan_state->taskqueue_stats().record_overflow(0)); |
0 | 1219 } |
1220 | |
1221 return new_obj; | |
1222 } | |
1223 | |
1224 // Oops. Someone beat us to it. Undo the allocation. Where did we | |
1225 // allocate it? | |
1226 if (is_in_reserved(new_obj)) { | |
1227 // Must be in to_space. | |
1228 assert(to()->is_in_reserved(new_obj), "Checking"); | |
1229 if (forward_ptr == ClaimedForwardPtr) { | |
1230 // Wait to get the real forwarding pointer value. | |
1231 forward_ptr = real_forwardee(old); | |
1232 } | |
1233 par_scan_state->undo_alloc_in_to_space((HeapWord*)new_obj, sz); | |
1234 } | |
1235 | |
1236 return forward_ptr; | |
1237 } | |
1238 | |
1239 | |
1240 // Multiple GC threads may try to promote the same object. If two | |
1241 // or more GC threads copy the object, only one wins the race to install | |
1242 // the forwarding pointer. The other threads have to undo their copy. | |
1243 | |
1244 oop ParNewGeneration::copy_to_survivor_space_with_undo( | |
1245 ParScanThreadState* par_scan_state, oop old, size_t sz, markOop m) { | |
1246 | |
1247 // In the sequential version, this assert also says that the object is | |
1248 // not forwarded. That might not be the case here. It is the case that | |
1249 // the caller observed it to be not forwarded at some time in the past. | |
1250 assert(is_in_reserved(old), "shouldn't be scavenging this oop"); | |
1251 | |
1252 // The sequential code read "old->age()" below. That doesn't work here, | |
1253 // since the age is in the mark word, and that might be overwritten with | |
1254 // a forwarding pointer by a parallel thread. So we must save the mark | |
1255 // word here, install it in a local oopDesc, and then analyze it. | |
1256 oopDesc dummyOld; | |
1257 dummyOld.set_mark(m); | |
1258 assert(!dummyOld.is_forwarded(), | |
1259 "should not be called with forwarding pointer mark word."); | |
1260 | |
1261 bool failed_to_promote = false; | |
1262 oop new_obj = NULL; | |
1263 oop forward_ptr; | |
1264 | |
1265 // Try allocating obj in to-space (unless too old) | |
1266 if (dummyOld.age() < tenuring_threshold()) { | |
1267 new_obj = (oop)par_scan_state->alloc_in_to_space(sz); | |
1268 if (new_obj == NULL) { | |
1269 set_survivor_overflow(true); | |
1270 } | |
1271 } | |
1272 | |
1273 if (new_obj == NULL) { | |
1274 // Either to-space is full or we decided to promote | |
1275 // try allocating obj tenured | |
1276 new_obj = _next_gen->par_promote(par_scan_state->thread_num(), | |
1277 old, m, sz); | |
1278 | |
1279 if (new_obj == NULL) { | |
1280 // promotion failed, forward to self | |
1281 forward_ptr = old->forward_to_atomic(old); | |
1282 new_obj = old; | |
1283 | |
1284 if (forward_ptr != NULL) { | |
1285 return forward_ptr; // someone else succeeded | |
1286 } | |
1287 | |
1288 _promotion_failed = true; | |
1289 failed_to_promote = true; | |
1290 | |
1291 preserve_mark_if_necessary(old, m); | |
1145
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1292 // Log the size of the maiden promotion failure |
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1293 par_scan_state->log_promotion_failure(sz); |
0 | 1294 } |
1295 } else { | |
1296 // Is in to-space; do copying ourselves. | |
1297 Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)new_obj, sz); | |
1298 // Restore the mark word copied above. | |
1299 new_obj->set_mark(m); | |
1300 // Increment age if new_obj still in new generation | |
1301 new_obj->incr_age(); | |
1302 par_scan_state->age_table()->add(new_obj, sz); | |
1303 } | |
1304 assert(new_obj != NULL, "just checking"); | |
1305 | |
1306 // Now attempt to install the forwarding pointer (atomically). | |
1307 // We have to copy the mark word before overwriting with forwarding | |
1308 // ptr, so we can restore it below in the copy. | |
1309 if (!failed_to_promote) { | |
1310 forward_ptr = old->forward_to_atomic(new_obj); | |
1311 } | |
1312 | |
1313 if (forward_ptr == NULL) { | |
1314 oop obj_to_push = new_obj; | |
1315 if (par_scan_state->should_be_partially_scanned(obj_to_push, old)) { | |
1316 // Length field used as index of next element to be scanned. | |
1317 // Real length can be obtained from real_forwardee() | |
1318 arrayOop(old)->set_length(0); | |
1319 obj_to_push = old; | |
1320 assert(obj_to_push->is_forwarded() && obj_to_push->forwardee() != obj_to_push, | |
1321 "push forwarded object"); | |
1322 } | |
1323 // Push it on one of the queues of to-be-scanned objects. | |
534 | 1324 bool simulate_overflow = false; |
1325 NOT_PRODUCT( | |
1326 if (ParGCWorkQueueOverflowALot && should_simulate_overflow()) { | |
1327 // simulate a stack overflow | |
1328 simulate_overflow = true; | |
1329 } | |
1330 ) | |
1331 if (simulate_overflow || !par_scan_state->work_queue()->push(obj_to_push)) { | |
0 | 1332 // Add stats for overflow pushes. |
534 | 1333 push_on_overflow_list(old, par_scan_state); |
1710 | 1334 TASKQUEUE_STATS_ONLY(par_scan_state->taskqueue_stats().record_overflow(0)); |
0 | 1335 } |
1336 | |
1337 return new_obj; | |
1338 } | |
1339 | |
1340 // Oops. Someone beat us to it. Undo the allocation. Where did we | |
1341 // allocate it? | |
1342 if (is_in_reserved(new_obj)) { | |
1343 // Must be in to_space. | |
1344 assert(to()->is_in_reserved(new_obj), "Checking"); | |
1345 par_scan_state->undo_alloc_in_to_space((HeapWord*)new_obj, sz); | |
1346 } else { | |
1347 assert(!_avoid_promotion_undo, "Should not be here if avoiding."); | |
1348 _next_gen->par_promote_alloc_undo(par_scan_state->thread_num(), | |
1349 (HeapWord*)new_obj, sz); | |
1350 } | |
1351 | |
1352 return forward_ptr; | |
1353 } | |
1354 | |
534 | 1355 #ifndef PRODUCT |
1356 // It's OK to call this multi-threaded; the worst thing | |
1357 // that can happen is that we'll get a bunch of closely | |
1358 // spaced simulated oveflows, but that's OK, in fact | |
1359 // probably good as it would exercise the overflow code | |
1360 // under contention. | |
1361 bool ParNewGeneration::should_simulate_overflow() { | |
1362 if (_overflow_counter-- <= 0) { // just being defensive | |
1363 _overflow_counter = ParGCWorkQueueOverflowInterval; | |
1364 return true; | |
1365 } else { | |
1366 return false; | |
1367 } | |
1368 } | |
1369 #endif | |
1370 | |
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1371 // In case we are using compressed oops, we need to be careful. |
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1372 // If the object being pushed is an object array, then its length |
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1373 // field keeps track of the "grey boundary" at which the next |
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1374 // incremental scan will be done (see ParGCArrayScanChunk). |
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1375 // When using compressed oops, this length field is kept in the |
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1376 // lower 32 bits of the erstwhile klass word and cannot be used |
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1377 // for the overflow chaining pointer (OCP below). As such the OCP |
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1378 // would itself need to be compressed into the top 32-bits in this |
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1379 // case. Unfortunately, see below, in the event that we have a |
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1380 // promotion failure, the node to be pushed on the list can be |
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1381 // outside of the Java heap, so the heap-based pointer compression |
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1382 // would not work (we would have potential aliasing between C-heap |
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1383 // and Java-heap pointers). For this reason, when using compressed |
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1384 // oops, we simply use a worker-thread-local, non-shared overflow |
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1385 // list in the form of a growable array, with a slightly different |
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1386 // overflow stack draining strategy. If/when we start using fat |
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1387 // stacks here, we can go back to using (fat) pointer chains |
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1388 // (although some performance comparisons would be useful since |
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1389 // single global lists have their own performance disadvantages |
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1390 // as we were made painfully aware not long ago, see 6786503). |
534 | 1391 #define BUSY (oop(0x1aff1aff)) |
1392 void ParNewGeneration::push_on_overflow_list(oop from_space_obj, ParScanThreadState* par_scan_state) { | |
679
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1393 assert(is_in_reserved(from_space_obj), "Should be from this generation"); |
695 | 1394 if (ParGCUseLocalOverflow) { |
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1395 // In the case of compressed oops, we use a private, not-shared |
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1396 // overflow stack. |
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1397 par_scan_state->push_on_overflow_stack(from_space_obj); |
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1398 } else { |
695 | 1399 assert(!UseCompressedOops, "Error"); |
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1400 // if the object has been forwarded to itself, then we cannot |
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1401 // use the klass pointer for the linked list. Instead we have |
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1402 // to allocate an oopDesc in the C-Heap and use that for the linked list. |
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1403 // XXX This is horribly inefficient when a promotion failure occurs |
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1404 // and should be fixed. XXX FIX ME !!! |
534 | 1405 #ifndef PRODUCT |
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1406 Atomic::inc_ptr(&_num_par_pushes); |
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1407 assert(_num_par_pushes > 0, "Tautology"); |
534 | 1408 #endif |
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1409 if (from_space_obj->forwardee() == from_space_obj) { |
6197 | 1410 oopDesc* listhead = NEW_C_HEAP_ARRAY(oopDesc, 1, mtGC); |
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1411 listhead->forward_to(from_space_obj); |
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1412 from_space_obj = listhead; |
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1413 } |
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1414 oop observed_overflow_list = _overflow_list; |
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1415 oop cur_overflow_list; |
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1416 do { |
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1417 cur_overflow_list = observed_overflow_list; |
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1418 if (cur_overflow_list != BUSY) { |
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1419 from_space_obj->set_klass_to_list_ptr(cur_overflow_list); |
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1420 } else { |
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1421 from_space_obj->set_klass_to_list_ptr(NULL); |
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1422 } |
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1423 observed_overflow_list = |
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1424 (oop)Atomic::cmpxchg_ptr(from_space_obj, &_overflow_list, cur_overflow_list); |
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1425 } while (cur_overflow_list != observed_overflow_list); |
0 | 1426 } |
1427 } | |
1428 | |
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1429 bool ParNewGeneration::take_from_overflow_list(ParScanThreadState* par_scan_state) { |
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1430 bool res; |
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1431 |
695 | 1432 if (ParGCUseLocalOverflow) { |
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1433 res = par_scan_state->take_from_overflow_stack(); |
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1434 } else { |
695 | 1435 assert(!UseCompressedOops, "Error"); |
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1436 res = take_from_overflow_list_work(par_scan_state); |
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1437 } |
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1438 return res; |
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1439 } |
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1440 |
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1441 |
534 | 1442 // *NOTE*: The overflow list manipulation code here and |
1443 // in CMSCollector:: are very similar in shape, | |
1444 // except that in the CMS case we thread the objects | |
1445 // directly into the list via their mark word, and do | |
1446 // not need to deal with special cases below related | |
1447 // to chunking of object arrays and promotion failure | |
1448 // handling. | |
1449 // CR 6797058 has been filed to attempt consolidation of | |
1450 // the common code. | |
1451 // Because of the common code, if you make any changes in | |
1452 // the code below, please check the CMS version to see if | |
1453 // similar changes might be needed. | |
1454 // See CMSCollector::par_take_from_overflow_list() for | |
1455 // more extensive documentation comments. | |
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1456 bool ParNewGeneration::take_from_overflow_list_work(ParScanThreadState* par_scan_state) { |
0 | 1457 ObjToScanQueue* work_q = par_scan_state->work_queue(); |
1458 // How many to take? | |
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1459 size_t objsFromOverflow = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
534 | 1460 (size_t)ParGCDesiredObjsFromOverflowList); |
0 | 1461 |
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1462 assert(!UseCompressedOops, "Error"); |
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1463 assert(par_scan_state->overflow_stack() == NULL, "Error"); |
0 | 1464 if (_overflow_list == NULL) return false; |
1465 | |
1466 // Otherwise, there was something there; try claiming the list. | |
534 | 1467 oop prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); |
1468 // Trim off a prefix of at most objsFromOverflow items | |
1469 Thread* tid = Thread::current(); | |
1470 size_t spin_count = (size_t)ParallelGCThreads; | |
1471 size_t sleep_time_millis = MAX2((size_t)1, objsFromOverflow/100); | |
1472 for (size_t spin = 0; prefix == BUSY && spin < spin_count; spin++) { | |
1473 // someone grabbed it before we did ... | |
1474 // ... we spin for a short while... | |
1475 os::sleep(tid, sleep_time_millis, false); | |
1476 if (_overflow_list == NULL) { | |
1477 // nothing left to take | |
1478 return false; | |
1479 } else if (_overflow_list != BUSY) { | |
1480 // try and grab the prefix | |
1481 prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); | |
1482 } | |
0 | 1483 } |
534 | 1484 if (prefix == NULL || prefix == BUSY) { |
1485 // Nothing to take or waited long enough | |
1486 if (prefix == NULL) { | |
1487 // Write back the NULL in case we overwrote it with BUSY above | |
1488 // and it is still the same value. | |
1489 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
1490 } | |
1491 return false; | |
1492 } | |
1493 assert(prefix != NULL && prefix != BUSY, "Error"); | |
1494 size_t i = 1; | |
0 | 1495 oop cur = prefix; |
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1496 while (i < objsFromOverflow && cur->klass_or_null() != NULL) { |
0 | 1497 i++; cur = oop(cur->klass()); |
1498 } | |
1499 | |
1500 // Reattach remaining (suffix) to overflow list | |
534 | 1501 if (cur->klass_or_null() == NULL) { |
1502 // Write back the NULL in lieu of the BUSY we wrote | |
1503 // above and it is still the same value. | |
1504 if (_overflow_list == BUSY) { | |
1505 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
0 | 1506 } |
534 | 1507 } else { |
1508 assert(cur->klass_or_null() != BUSY, "Error"); | |
1509 oop suffix = oop(cur->klass()); // suffix will be put back on global list | |
1510 cur->set_klass_to_list_ptr(NULL); // break off suffix | |
1511 // It's possible that the list is still in the empty(busy) state | |
1512 // we left it in a short while ago; in that case we may be | |
1513 // able to place back the suffix. | |
1514 oop observed_overflow_list = _overflow_list; | |
1515 oop cur_overflow_list = observed_overflow_list; | |
1516 bool attached = false; | |
1517 while (observed_overflow_list == BUSY || observed_overflow_list == NULL) { | |
1518 observed_overflow_list = | |
1519 (oop) Atomic::cmpxchg_ptr(suffix, &_overflow_list, cur_overflow_list); | |
1520 if (cur_overflow_list == observed_overflow_list) { | |
1521 attached = true; | |
1522 break; | |
1523 } else cur_overflow_list = observed_overflow_list; | |
1524 } | |
1525 if (!attached) { | |
1526 // Too bad, someone else got in in between; we'll need to do a splice. | |
1527 // Find the last item of suffix list | |
1528 oop last = suffix; | |
1529 while (last->klass_or_null() != NULL) { | |
1530 last = oop(last->klass()); | |
1531 } | |
1532 // Atomically prepend suffix to current overflow list | |
1533 observed_overflow_list = _overflow_list; | |
1534 do { | |
1535 cur_overflow_list = observed_overflow_list; | |
1536 if (cur_overflow_list != BUSY) { | |
1537 // Do the splice ... | |
1538 last->set_klass_to_list_ptr(cur_overflow_list); | |
1539 } else { // cur_overflow_list == BUSY | |
1540 last->set_klass_to_list_ptr(NULL); | |
1541 } | |
1542 observed_overflow_list = | |
1543 (oop)Atomic::cmpxchg_ptr(suffix, &_overflow_list, cur_overflow_list); | |
1544 } while (cur_overflow_list != observed_overflow_list); | |
0 | 1545 } |
1546 } | |
1547 | |
1548 // Push objects on prefix list onto this thread's work queue | |
534 | 1549 assert(prefix != NULL && prefix != BUSY, "program logic"); |
0 | 1550 cur = prefix; |
534 | 1551 ssize_t n = 0; |
0 | 1552 while (cur != NULL) { |
1553 oop obj_to_push = cur->forwardee(); | |
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1554 oop next = oop(cur->klass_or_null()); |
0 | 1555 cur->set_klass(obj_to_push->klass()); |
534 | 1556 // This may be an array object that is self-forwarded. In that case, the list pointer |
1557 // space, cur, is not in the Java heap, but rather in the C-heap and should be freed. | |
1558 if (!is_in_reserved(cur)) { | |
1559 // This can become a scaling bottleneck when there is work queue overflow coincident | |
1560 // with promotion failure. | |
1561 oopDesc* f = cur; | |
6197 | 1562 FREE_C_HEAP_ARRAY(oopDesc, f, mtGC); |
534 | 1563 } else if (par_scan_state->should_be_partially_scanned(obj_to_push, cur)) { |
0 | 1564 assert(arrayOop(cur)->length() == 0, "entire array remaining to be scanned"); |
534 | 1565 obj_to_push = cur; |
0 | 1566 } |
534 | 1567 bool ok = work_q->push(obj_to_push); |
1568 assert(ok, "Should have succeeded"); | |
0 | 1569 cur = next; |
1570 n++; | |
1571 } | |
1710 | 1572 TASKQUEUE_STATS_ONLY(par_scan_state->note_overflow_refill(n)); |
534 | 1573 #ifndef PRODUCT |
1574 assert(_num_par_pushes >= n, "Too many pops?"); | |
1575 Atomic::add_ptr(-(intptr_t)n, &_num_par_pushes); | |
1576 #endif | |
0 | 1577 return true; |
1578 } | |
534 | 1579 #undef BUSY |
0 | 1580 |
1581 void ParNewGeneration::ref_processor_init() | |
1582 { | |
1583 if (_ref_processor == NULL) { | |
1584 // Allocate and initialize a reference processor | |
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1585 _ref_processor = |
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1586 new ReferenceProcessor(_reserved, // span |
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1587 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing |
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1588 (int) ParallelGCThreads, // mt processing degree |
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1589 refs_discovery_is_mt(), // mt discovery |
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1590 (int) ParallelGCThreads, // mt discovery degree |
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1591 refs_discovery_is_atomic(), // atomic_discovery |
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1592 NULL, // is_alive_non_header |
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1593 false); // write barrier for next field updates |
0 | 1594 } |
1595 } | |
1596 | |
1597 const char* ParNewGeneration::name() const { | |
1598 return "par new generation"; | |
1599 } | |
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1600 |
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1601 bool ParNewGeneration::in_use() { |
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1602 return UseParNewGC && ParallelGCThreads > 0; |
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1603 } |