Mercurial > hg > graal-jvmci-8
annotate src/share/vm/gc_implementation/parNew/parNewGeneration.cpp @ 20254:9fec19bb0659
8032379: Remove the is_scavenging flag to process_strong_roots
Summary: Refactor the strong root processing to avoid using a boolean in addition to the ScanOption enum.
Reviewed-by: stefank, tschatzl, ehelin, jmasa
author | mgerdin |
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date | Tue, 14 Jan 2014 16:40:33 +0100 |
parents | ce8f6bb717c9 |
children | 7426d8d76305 |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 2001, 2014, 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" |
10405 | 32 #include "gc_implementation/shared/gcHeapSummary.hpp" |
33 #include "gc_implementation/shared/gcTimer.hpp" | |
34 #include "gc_implementation/shared/gcTrace.hpp" | |
35 #include "gc_implementation/shared/gcTraceTime.hpp" | |
36 #include "gc_implementation/shared/copyFailedInfo.hpp" | |
1972 | 37 #include "gc_implementation/shared/spaceDecorator.hpp" |
38 #include "memory/defNewGeneration.inline.hpp" | |
39 #include "memory/genCollectedHeap.hpp" | |
40 #include "memory/genOopClosures.inline.hpp" | |
41 #include "memory/generation.hpp" | |
42 #include "memory/generation.inline.hpp" | |
43 #include "memory/referencePolicy.hpp" | |
44 #include "memory/resourceArea.hpp" | |
45 #include "memory/sharedHeap.hpp" | |
46 #include "memory/space.hpp" | |
47 #include "oops/objArrayOop.hpp" | |
48 #include "oops/oop.inline.hpp" | |
49 #include "oops/oop.pcgc.inline.hpp" | |
50 #include "runtime/handles.hpp" | |
51 #include "runtime/handles.inline.hpp" | |
52 #include "runtime/java.hpp" | |
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53 #include "runtime/thread.inline.hpp" |
1972 | 54 #include "utilities/copy.hpp" |
55 #include "utilities/globalDefinitions.hpp" | |
56 #include "utilities/workgroup.hpp" | |
0 | 57 |
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58 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC |
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59 |
0 | 60 #ifdef _MSC_VER |
61 #pragma warning( push ) | |
62 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list | |
63 #endif | |
64 ParScanThreadState::ParScanThreadState(Space* to_space_, | |
65 ParNewGeneration* gen_, | |
66 Generation* old_gen_, | |
67 int thread_num_, | |
68 ObjToScanQueueSet* work_queue_set_, | |
6197 | 69 Stack<oop, mtGC>* overflow_stacks_, |
0 | 70 size_t desired_plab_sz_, |
71 ParallelTaskTerminator& term_) : | |
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72 _to_space(to_space_), _old_gen(old_gen_), _young_gen(gen_), _thread_num(thread_num_), |
0 | 73 _work_queue(work_queue_set_->queue(thread_num_)), _to_space_full(false), |
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74 _overflow_stack(overflow_stacks_ ? overflow_stacks_ + thread_num_ : NULL), |
0 | 75 _ageTable(false), // false ==> not the global age table, no perf data. |
76 _to_space_alloc_buffer(desired_plab_sz_), | |
77 _to_space_closure(gen_, this), _old_gen_closure(gen_, this), | |
78 _to_space_root_closure(gen_, this), _old_gen_root_closure(gen_, this), | |
79 _older_gen_closure(gen_, this), | |
80 _evacuate_followers(this, &_to_space_closure, &_old_gen_closure, | |
81 &_to_space_root_closure, gen_, &_old_gen_root_closure, | |
82 work_queue_set_, &term_), | |
83 _is_alive_closure(gen_), _scan_weak_ref_closure(gen_, this), | |
84 _keep_alive_closure(&_scan_weak_ref_closure), | |
85 _strong_roots_time(0.0), _term_time(0.0) | |
86 { | |
1710 | 87 #if TASKQUEUE_STATS |
88 _term_attempts = 0; | |
89 _overflow_refills = 0; | |
90 _overflow_refill_objs = 0; | |
91 #endif // TASKQUEUE_STATS | |
92 | |
0 | 93 _survivor_chunk_array = |
94 (ChunkArray*) old_gen()->get_data_recorder(thread_num()); | |
95 _hash_seed = 17; // Might want to take time-based random value. | |
96 _start = os::elapsedTime(); | |
97 _old_gen_closure.set_generation(old_gen_); | |
98 _old_gen_root_closure.set_generation(old_gen_); | |
99 } | |
100 #ifdef _MSC_VER | |
101 #pragma warning( pop ) | |
102 #endif | |
103 | |
104 void ParScanThreadState::record_survivor_plab(HeapWord* plab_start, | |
105 size_t plab_word_size) { | |
106 ChunkArray* sca = survivor_chunk_array(); | |
107 if (sca != NULL) { | |
108 // A non-null SCA implies that we want the PLAB data recorded. | |
109 sca->record_sample(plab_start, plab_word_size); | |
110 } | |
111 } | |
112 | |
113 bool ParScanThreadState::should_be_partially_scanned(oop new_obj, oop old_obj) const { | |
114 return new_obj->is_objArray() && | |
115 arrayOop(new_obj)->length() > ParGCArrayScanChunk && | |
116 new_obj != old_obj; | |
117 } | |
118 | |
119 void ParScanThreadState::scan_partial_array_and_push_remainder(oop old) { | |
120 assert(old->is_objArray(), "must be obj array"); | |
121 assert(old->is_forwarded(), "must be forwarded"); | |
122 assert(Universe::heap()->is_in_reserved(old), "must be in heap."); | |
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123 assert(!old_gen()->is_in(old), "must be in young generation."); |
0 | 124 |
125 objArrayOop obj = objArrayOop(old->forwardee()); | |
126 // Process ParGCArrayScanChunk elements now | |
127 // and push the remainder back onto queue | |
128 int start = arrayOop(old)->length(); | |
129 int end = obj->length(); | |
130 int remainder = end - start; | |
131 assert(start <= end, "just checking"); | |
132 if (remainder > 2 * ParGCArrayScanChunk) { | |
133 // Test above combines last partial chunk with a full chunk | |
134 end = start + ParGCArrayScanChunk; | |
135 arrayOop(old)->set_length(end); | |
136 // Push remainder. | |
137 bool ok = work_queue()->push(old); | |
138 assert(ok, "just popped, push must be okay"); | |
139 } else { | |
140 // Restore length so that it can be used if there | |
141 // is a promotion failure and forwarding pointers | |
142 // must be removed. | |
143 arrayOop(old)->set_length(end); | |
144 } | |
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145 |
0 | 146 // process our set of indices (include header in first chunk) |
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147 // should make sure end is even (aligned to HeapWord in case of compressed oops) |
0 | 148 if ((HeapWord *)obj < young_old_boundary()) { |
149 // object is in to_space | |
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150 obj->oop_iterate_range(&_to_space_closure, start, end); |
0 | 151 } else { |
152 // object is in old generation | |
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153 obj->oop_iterate_range(&_old_gen_closure, start, end); |
0 | 154 } |
155 } | |
156 | |
157 | |
158 void ParScanThreadState::trim_queues(int max_size) { | |
159 ObjToScanQueue* queue = work_queue(); | |
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160 do { |
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161 while (queue->size() > (juint)max_size) { |
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162 oop obj_to_scan; |
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163 if (queue->pop_local(obj_to_scan)) { |
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164 if ((HeapWord *)obj_to_scan < young_old_boundary()) { |
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165 if (obj_to_scan->is_objArray() && |
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166 obj_to_scan->is_forwarded() && |
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167 obj_to_scan->forwardee() != obj_to_scan) { |
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168 scan_partial_array_and_push_remainder(obj_to_scan); |
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169 } else { |
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170 // object is in to_space |
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171 obj_to_scan->oop_iterate(&_to_space_closure); |
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172 } |
0 | 173 } else { |
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174 // object is in old generation |
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175 obj_to_scan->oop_iterate(&_old_gen_closure); |
0 | 176 } |
177 } | |
178 } | |
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179 // For the case of compressed oops, we have a private, non-shared |
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180 // overflow stack, so we eagerly drain it so as to more evenly |
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181 // distribute load early. Note: this may be good to do in |
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182 // general rather than delay for the final stealing phase. |
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183 // If applicable, we'll transfer a set of objects over to our |
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184 // work queue, allowing them to be stolen and draining our |
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185 // private overflow stack. |
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186 } while (ParGCTrimOverflow && young_gen()->take_from_overflow_list(this)); |
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187 } |
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188 |
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189 bool ParScanThreadState::take_from_overflow_stack() { |
695 | 190 assert(ParGCUseLocalOverflow, "Else should not call"); |
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191 assert(young_gen()->overflow_list() == NULL, "Error"); |
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192 ObjToScanQueue* queue = work_queue(); |
6197 | 193 Stack<oop, mtGC>* const of_stack = overflow_stack(); |
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194 const size_t num_overflow_elems = of_stack->size(); |
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195 const size_t space_available = queue->max_elems() - queue->size(); |
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196 const size_t num_take_elems = MIN3(space_available / 4, |
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197 ParGCDesiredObjsFromOverflowList, |
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198 num_overflow_elems); |
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199 // Transfer the most recent num_take_elems from the overflow |
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200 // stack to our work queue. |
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201 for (size_t i = 0; i != num_take_elems; i++) { |
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202 oop cur = of_stack->pop(); |
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203 oop obj_to_push = cur->forwardee(); |
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204 assert(Universe::heap()->is_in_reserved(cur), "Should be in heap"); |
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205 assert(!old_gen()->is_in_reserved(cur), "Should be in young gen"); |
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206 assert(Universe::heap()->is_in_reserved(obj_to_push), "Should be in heap"); |
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207 if (should_be_partially_scanned(obj_to_push, cur)) { |
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208 assert(arrayOop(cur)->length() == 0, "entire array remaining to be scanned"); |
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209 obj_to_push = cur; |
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210 } |
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211 bool ok = queue->push(obj_to_push); |
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212 assert(ok, "Should have succeeded"); |
0 | 213 } |
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214 assert(young_gen()->overflow_list() == NULL, "Error"); |
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215 return num_take_elems > 0; // was something transferred? |
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216 } |
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217 |
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218 void ParScanThreadState::push_on_overflow_stack(oop p) { |
695 | 219 assert(ParGCUseLocalOverflow, "Else should not call"); |
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220 overflow_stack()->push(p); |
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221 assert(young_gen()->overflow_list() == NULL, "Error"); |
0 | 222 } |
223 | |
224 HeapWord* ParScanThreadState::alloc_in_to_space_slow(size_t word_sz) { | |
225 | |
226 // Otherwise, if the object is small enough, try to reallocate the | |
227 // buffer. | |
228 HeapWord* obj = NULL; | |
229 if (!_to_space_full) { | |
230 ParGCAllocBuffer* const plab = to_space_alloc_buffer(); | |
231 Space* const sp = to_space(); | |
232 if (word_sz * 100 < | |
233 ParallelGCBufferWastePct * plab->word_sz()) { | |
234 // Is small enough; abandon this buffer and start a new one. | |
235 plab->retire(false, false); | |
236 size_t buf_size = plab->word_sz(); | |
237 HeapWord* buf_space = sp->par_allocate(buf_size); | |
238 if (buf_space == NULL) { | |
239 const size_t min_bytes = | |
240 ParGCAllocBuffer::min_size() << LogHeapWordSize; | |
241 size_t free_bytes = sp->free(); | |
242 while(buf_space == NULL && free_bytes >= min_bytes) { | |
243 buf_size = free_bytes >> LogHeapWordSize; | |
244 assert(buf_size == (size_t)align_object_size(buf_size), | |
245 "Invariant"); | |
246 buf_space = sp->par_allocate(buf_size); | |
247 free_bytes = sp->free(); | |
248 } | |
249 } | |
250 if (buf_space != NULL) { | |
251 plab->set_word_size(buf_size); | |
252 plab->set_buf(buf_space); | |
253 record_survivor_plab(buf_space, buf_size); | |
254 obj = plab->allocate(word_sz); | |
255 // Note that we cannot compare buf_size < word_sz below | |
256 // because of AlignmentReserve (see ParGCAllocBuffer::allocate()). | |
257 assert(obj != NULL || plab->words_remaining() < word_sz, | |
258 "Else should have been able to allocate"); | |
259 // It's conceivable that we may be able to use the | |
260 // buffer we just grabbed for subsequent small requests | |
261 // even if not for this one. | |
262 } else { | |
263 // We're used up. | |
264 _to_space_full = true; | |
265 } | |
266 | |
267 } else { | |
268 // Too large; allocate the object individually. | |
269 obj = sp->par_allocate(word_sz); | |
270 } | |
271 } | |
272 return obj; | |
273 } | |
274 | |
275 | |
276 void ParScanThreadState::undo_alloc_in_to_space(HeapWord* obj, | |
277 size_t word_sz) { | |
278 // Is the alloc in the current alloc buffer? | |
279 if (to_space_alloc_buffer()->contains(obj)) { | |
280 assert(to_space_alloc_buffer()->contains(obj + word_sz - 1), | |
281 "Should contain whole object."); | |
282 to_space_alloc_buffer()->undo_allocation(obj, word_sz); | |
283 } else { | |
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284 CollectedHeap::fill_with_object(obj, word_sz); |
0 | 285 } |
286 } | |
287 | |
10405 | 288 void ParScanThreadState::print_promotion_failure_size() { |
289 if (_promotion_failed_info.has_failed() && PrintPromotionFailure) { | |
290 gclog_or_tty->print(" (%d: promotion failure size = " SIZE_FORMAT ") ", | |
291 _thread_num, _promotion_failed_info.first_size()); | |
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292 } |
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293 } |
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294 |
0 | 295 class ParScanThreadStateSet: private ResourceArray { |
296 public: | |
297 // Initializes states for the specified number of threads; | |
298 ParScanThreadStateSet(int num_threads, | |
299 Space& to_space, | |
300 ParNewGeneration& gen, | |
301 Generation& old_gen, | |
302 ObjToScanQueueSet& queue_set, | |
6197 | 303 Stack<oop, mtGC>* overflow_stacks_, |
0 | 304 size_t desired_plab_sz, |
305 ParallelTaskTerminator& term); | |
1710 | 306 |
307 ~ParScanThreadStateSet() { TASKQUEUE_STATS_ONLY(reset_stats()); } | |
308 | |
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309 inline ParScanThreadState& thread_state(int i); |
1710 | 310 |
10405 | 311 void trace_promotion_failed(YoungGCTracer& gc_tracer); |
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312 void reset(int active_workers, bool promotion_failed); |
0 | 313 void flush(); |
1710 | 314 |
315 #if TASKQUEUE_STATS | |
316 static void | |
317 print_termination_stats_hdr(outputStream* const st = gclog_or_tty); | |
318 void print_termination_stats(outputStream* const st = gclog_or_tty); | |
319 static void | |
320 print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); | |
321 void print_taskqueue_stats(outputStream* const st = gclog_or_tty); | |
322 void reset_stats(); | |
323 #endif // TASKQUEUE_STATS | |
324 | |
0 | 325 private: |
326 ParallelTaskTerminator& _term; | |
327 ParNewGeneration& _gen; | |
328 Generation& _next_gen; | |
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329 public: |
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330 bool is_valid(int id) const { return id < length(); } |
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331 ParallelTaskTerminator* terminator() { return &_term; } |
0 | 332 }; |
333 | |
334 | |
335 ParScanThreadStateSet::ParScanThreadStateSet( | |
336 int num_threads, Space& to_space, ParNewGeneration& gen, | |
337 Generation& old_gen, ObjToScanQueueSet& queue_set, | |
6197 | 338 Stack<oop, mtGC>* overflow_stacks, |
0 | 339 size_t desired_plab_sz, ParallelTaskTerminator& term) |
340 : ResourceArray(sizeof(ParScanThreadState), num_threads), | |
1710 | 341 _gen(gen), _next_gen(old_gen), _term(term) |
0 | 342 { |
343 assert(num_threads > 0, "sanity check!"); | |
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344 assert(ParGCUseLocalOverflow == (overflow_stacks != NULL), |
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345 "overflow_stack allocation mismatch"); |
0 | 346 // Initialize states. |
347 for (int i = 0; i < num_threads; ++i) { | |
348 new ((ParScanThreadState*)_data + i) | |
349 ParScanThreadState(&to_space, &gen, &old_gen, i, &queue_set, | |
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350 overflow_stacks, desired_plab_sz, term); |
0 | 351 } |
352 } | |
353 | |
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354 inline ParScanThreadState& ParScanThreadStateSet::thread_state(int i) |
0 | 355 { |
356 assert(i >= 0 && i < length(), "sanity check!"); | |
357 return ((ParScanThreadState*)_data)[i]; | |
358 } | |
359 | |
10405 | 360 void ParScanThreadStateSet::trace_promotion_failed(YoungGCTracer& gc_tracer) { |
361 for (int i = 0; i < length(); ++i) { | |
362 if (thread_state(i).promotion_failed()) { | |
363 gc_tracer.report_promotion_failed(thread_state(i).promotion_failed_info()); | |
364 thread_state(i).promotion_failed_info().reset(); | |
365 } | |
366 } | |
367 } | |
0 | 368 |
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369 void ParScanThreadStateSet::reset(int active_threads, bool promotion_failed) |
0 | 370 { |
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371 _term.reset_for_reuse(active_threads); |
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372 if (promotion_failed) { |
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373 for (int i = 0; i < length(); ++i) { |
10405 | 374 thread_state(i).print_promotion_failure_size(); |
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375 } |
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376 } |
0 | 377 } |
378 | |
1710 | 379 #if TASKQUEUE_STATS |
380 void | |
381 ParScanThreadState::reset_stats() | |
382 { | |
383 taskqueue_stats().reset(); | |
384 _term_attempts = 0; | |
385 _overflow_refills = 0; | |
386 _overflow_refill_objs = 0; | |
387 } | |
388 | |
389 void ParScanThreadStateSet::reset_stats() | |
390 { | |
391 for (int i = 0; i < length(); ++i) { | |
392 thread_state(i).reset_stats(); | |
393 } | |
394 } | |
395 | |
396 void | |
397 ParScanThreadStateSet::print_termination_stats_hdr(outputStream* const st) | |
398 { | |
399 st->print_raw_cr("GC Termination Stats"); | |
400 st->print_raw_cr(" elapsed --strong roots-- " | |
401 "-------termination-------"); | |
402 st->print_raw_cr("thr ms ms % " | |
403 " ms % attempts"); | |
404 st->print_raw_cr("--- --------- --------- ------ " | |
405 "--------- ------ --------"); | |
406 } | |
407 | |
408 void ParScanThreadStateSet::print_termination_stats(outputStream* const st) | |
409 { | |
410 print_termination_stats_hdr(st); | |
411 | |
412 for (int i = 0; i < length(); ++i) { | |
413 const ParScanThreadState & pss = thread_state(i); | |
414 const double elapsed_ms = pss.elapsed_time() * 1000.0; | |
415 const double s_roots_ms = pss.strong_roots_time() * 1000.0; | |
416 const double term_ms = pss.term_time() * 1000.0; | |
417 st->print_cr("%3d %9.2f %9.2f %6.2f " | |
418 "%9.2f %6.2f " SIZE_FORMAT_W(8), | |
419 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms, | |
420 term_ms, term_ms * 100 / elapsed_ms, pss.term_attempts()); | |
421 } | |
422 } | |
423 | |
424 // Print stats related to work queue activity. | |
425 void ParScanThreadStateSet::print_taskqueue_stats_hdr(outputStream* const st) | |
426 { | |
427 st->print_raw_cr("GC Task Stats"); | |
428 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); | |
429 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); | |
430 } | |
431 | |
432 void ParScanThreadStateSet::print_taskqueue_stats(outputStream* const st) | |
433 { | |
434 print_taskqueue_stats_hdr(st); | |
435 | |
436 TaskQueueStats totals; | |
437 for (int i = 0; i < length(); ++i) { | |
438 const ParScanThreadState & pss = thread_state(i); | |
439 const TaskQueueStats & stats = pss.taskqueue_stats(); | |
440 st->print("%3d ", i); stats.print(st); st->cr(); | |
441 totals += stats; | |
442 | |
443 if (pss.overflow_refills() > 0) { | |
444 st->print_cr(" " SIZE_FORMAT_W(10) " overflow refills " | |
445 SIZE_FORMAT_W(10) " overflow objects", | |
446 pss.overflow_refills(), pss.overflow_refill_objs()); | |
447 } | |
448 } | |
449 st->print("tot "); totals.print(st); st->cr(); | |
450 | |
451 DEBUG_ONLY(totals.verify()); | |
452 } | |
453 #endif // TASKQUEUE_STATS | |
454 | |
0 | 455 void ParScanThreadStateSet::flush() |
456 { | |
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457 // Work in this loop should be kept as lightweight as |
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458 // possible since this might otherwise become a bottleneck |
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459 // to scaling. Should we add heavy-weight work into this |
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460 // loop, consider parallelizing the loop into the worker threads. |
0 | 461 for (int i = 0; i < length(); ++i) { |
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462 ParScanThreadState& par_scan_state = thread_state(i); |
0 | 463 |
464 // Flush stats related to To-space PLAB activity and | |
465 // retire the last buffer. | |
466 par_scan_state.to_space_alloc_buffer()-> | |
467 flush_stats_and_retire(_gen.plab_stats(), | |
6595 | 468 true /* end_of_gc */, |
469 false /* retain */); | |
0 | 470 |
471 // Every thread has its own age table. We need to merge | |
472 // them all into one. | |
473 ageTable *local_table = par_scan_state.age_table(); | |
474 _gen.age_table()->merge(local_table); | |
475 | |
476 // Inform old gen that we're done. | |
477 _next_gen.par_promote_alloc_done(i); | |
478 _next_gen.par_oop_since_save_marks_iterate_done(i); | |
1710 | 479 } |
0 | 480 |
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481 if (UseConcMarkSweepGC && ParallelGCThreads > 0) { |
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482 // We need to call this even when ResizeOldPLAB is disabled |
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483 // so as to avoid breaking some asserts. While we may be able |
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484 // to avoid this by reorganizing the code a bit, I am loathe |
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485 // to do that unless we find cases where ergo leads to bad |
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486 // performance. |
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487 CFLS_LAB::compute_desired_plab_size(); |
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488 } |
0 | 489 } |
490 | |
491 ParScanClosure::ParScanClosure(ParNewGeneration* g, | |
492 ParScanThreadState* par_scan_state) : | |
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493 OopsInKlassOrGenClosure(g), _par_scan_state(par_scan_state), _g(g) |
0 | 494 { |
495 assert(_g->level() == 0, "Optimized for youngest generation"); | |
496 _boundary = _g->reserved().end(); | |
497 } | |
498 | |
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499 void ParScanWithBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, true, false); } |
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500 void ParScanWithBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, true, false); } |
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501 |
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502 void ParScanWithoutBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, false, false); } |
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503 void ParScanWithoutBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, false, false); } |
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504 |
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505 void ParRootScanWithBarrierTwoGensClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, true, true); } |
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506 void ParRootScanWithBarrierTwoGensClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, true, true); } |
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507 |
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508 void ParRootScanWithoutBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, false, true); } |
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509 void ParRootScanWithoutBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, false, true); } |
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510 |
0 | 511 ParScanWeakRefClosure::ParScanWeakRefClosure(ParNewGeneration* g, |
512 ParScanThreadState* par_scan_state) | |
513 : ScanWeakRefClosure(g), _par_scan_state(par_scan_state) | |
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514 {} |
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515 |
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516 void ParScanWeakRefClosure::do_oop(oop* p) { ParScanWeakRefClosure::do_oop_work(p); } |
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517 void ParScanWeakRefClosure::do_oop(narrowOop* p) { ParScanWeakRefClosure::do_oop_work(p); } |
0 | 518 |
519 #ifdef WIN32 | |
520 #pragma warning(disable: 4786) /* identifier was truncated to '255' characters in the browser information */ | |
521 #endif | |
522 | |
523 ParEvacuateFollowersClosure::ParEvacuateFollowersClosure( | |
524 ParScanThreadState* par_scan_state_, | |
525 ParScanWithoutBarrierClosure* to_space_closure_, | |
526 ParScanWithBarrierClosure* old_gen_closure_, | |
527 ParRootScanWithoutBarrierClosure* to_space_root_closure_, | |
528 ParNewGeneration* par_gen_, | |
529 ParRootScanWithBarrierTwoGensClosure* old_gen_root_closure_, | |
530 ObjToScanQueueSet* task_queues_, | |
531 ParallelTaskTerminator* terminator_) : | |
532 | |
533 _par_scan_state(par_scan_state_), | |
534 _to_space_closure(to_space_closure_), | |
535 _old_gen_closure(old_gen_closure_), | |
536 _to_space_root_closure(to_space_root_closure_), | |
537 _old_gen_root_closure(old_gen_root_closure_), | |
538 _par_gen(par_gen_), | |
539 _task_queues(task_queues_), | |
540 _terminator(terminator_) | |
541 {} | |
542 | |
543 void ParEvacuateFollowersClosure::do_void() { | |
544 ObjToScanQueue* work_q = par_scan_state()->work_queue(); | |
545 | |
546 while (true) { | |
547 | |
548 // Scan to-space and old-gen objs until we run out of both. | |
549 oop obj_to_scan; | |
550 par_scan_state()->trim_queues(0); | |
551 | |
552 // We have no local work, attempt to steal from other threads. | |
553 | |
554 // attempt to steal work from promoted. | |
555 if (task_queues()->steal(par_scan_state()->thread_num(), | |
556 par_scan_state()->hash_seed(), | |
557 obj_to_scan)) { | |
558 bool res = work_q->push(obj_to_scan); | |
559 assert(res, "Empty queue should have room for a push."); | |
560 | |
561 // if successful, goto Start. | |
562 continue; | |
563 | |
564 // try global overflow list. | |
565 } else if (par_gen()->take_from_overflow_list(par_scan_state())) { | |
566 continue; | |
567 } | |
568 | |
569 // Otherwise, offer termination. | |
570 par_scan_state()->start_term_time(); | |
571 if (terminator()->offer_termination()) break; | |
572 par_scan_state()->end_term_time(); | |
573 } | |
534 | 574 assert(par_gen()->_overflow_list == NULL && par_gen()->_num_par_pushes == 0, |
575 "Broken overflow list?"); | |
0 | 576 // Finish the last termination pause. |
577 par_scan_state()->end_term_time(); | |
578 } | |
579 | |
580 ParNewGenTask::ParNewGenTask(ParNewGeneration* gen, Generation* next_gen, | |
581 HeapWord* young_old_boundary, ParScanThreadStateSet* state_set) : | |
582 AbstractGangTask("ParNewGeneration collection"), | |
583 _gen(gen), _next_gen(next_gen), | |
584 _young_old_boundary(young_old_boundary), | |
585 _state_set(state_set) | |
586 {} | |
587 | |
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588 // Reset the terminator for the given number of |
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589 // active threads. |
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590 void ParNewGenTask::set_for_termination(int active_workers) { |
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591 _state_set->reset(active_workers, _gen->promotion_failed()); |
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592 // Should the heap be passed in? There's only 1 for now so |
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593 // grab it instead. |
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594 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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595 gch->set_n_termination(active_workers); |
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596 } |
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597 |
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598 void ParNewGenTask::work(uint worker_id) { |
0 | 599 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
600 // Since this is being done in a separate thread, need new resource | |
601 // and handle marks. | |
602 ResourceMark rm; | |
603 HandleMark hm; | |
604 // We would need multiple old-gen queues otherwise. | |
679
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605 assert(gch->n_gens() == 2, "Par young collection currently only works with one older gen."); |
0 | 606 |
607 Generation* old_gen = gch->next_gen(_gen); | |
608 | |
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609 ParScanThreadState& par_scan_state = _state_set->thread_state(worker_id); |
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610 assert(_state_set->is_valid(worker_id), "Should not have been called"); |
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611 |
0 | 612 par_scan_state.set_young_old_boundary(_young_old_boundary); |
613 | |
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614 KlassScanClosure klass_scan_closure(&par_scan_state.to_space_root_closure(), |
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615 gch->rem_set()->klass_rem_set()); |
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616 |
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617 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_ScavengeCodeCache; |
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618 |
0 | 619 par_scan_state.start_strong_roots(); |
620 gch->gen_process_strong_roots(_gen->level(), | |
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621 true, // Process younger gens, if any, |
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622 // as strong roots. |
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623 false, // no scope; this is parallel code |
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624 SharedHeap::ScanningOption(so), |
989
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625 &par_scan_state.to_space_root_closure(), |
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626 true, // walk *all* scavengable nmethods |
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627 &par_scan_state.older_gen_closure(), |
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628 &klass_scan_closure); |
0 | 629 par_scan_state.end_strong_roots(); |
630 | |
631 // "evacuate followers". | |
632 par_scan_state.evacuate_followers_closure().do_void(); | |
633 } | |
634 | |
635 #ifdef _MSC_VER | |
636 #pragma warning( push ) | |
637 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list | |
638 #endif | |
639 ParNewGeneration:: | |
640 ParNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level) | |
641 : DefNewGeneration(rs, initial_byte_size, level, "PCopy"), | |
642 _overflow_list(NULL), | |
643 _is_alive_closure(this), | |
644 _plab_stats(YoungPLABSize, PLABWeight) | |
645 { | |
534 | 646 NOT_PRODUCT(_overflow_counter = ParGCWorkQueueOverflowInterval;) |
647 NOT_PRODUCT(_num_par_pushes = 0;) | |
0 | 648 _task_queues = new ObjToScanQueueSet(ParallelGCThreads); |
649 guarantee(_task_queues != NULL, "task_queues allocation failure."); | |
650 | |
651 for (uint i1 = 0; i1 < ParallelGCThreads; i1++) { | |
1665 | 652 ObjToScanQueue *q = new ObjToScanQueue(); |
653 guarantee(q != NULL, "work_queue Allocation failure."); | |
654 _task_queues->register_queue(i1, q); | |
0 | 655 } |
656 | |
657 for (uint i2 = 0; i2 < ParallelGCThreads; i2++) | |
658 _task_queues->queue(i2)->initialize(); | |
659 | |
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660 _overflow_stacks = NULL; |
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661 if (ParGCUseLocalOverflow) { |
6197 | 662 |
663 // typedef to workaround NEW_C_HEAP_ARRAY macro, which can not deal | |
664 // with ',' | |
665 typedef Stack<oop, mtGC> GCOopStack; | |
666 | |
667 _overflow_stacks = NEW_C_HEAP_ARRAY(GCOopStack, ParallelGCThreads, mtGC); | |
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668 for (size_t i = 0; i < ParallelGCThreads; ++i) { |
6197 | 669 new (_overflow_stacks + i) Stack<oop, mtGC>(); |
695 | 670 } |
671 } | |
672 | |
0 | 673 if (UsePerfData) { |
674 EXCEPTION_MARK; | |
675 ResourceMark rm; | |
676 | |
677 const char* cname = | |
678 PerfDataManager::counter_name(_gen_counters->name_space(), "threads"); | |
679 PerfDataManager::create_constant(SUN_GC, cname, PerfData::U_None, | |
680 ParallelGCThreads, CHECK); | |
681 } | |
682 } | |
683 #ifdef _MSC_VER | |
684 #pragma warning( pop ) | |
685 #endif | |
686 | |
687 // ParNewGeneration:: | |
688 ParKeepAliveClosure::ParKeepAliveClosure(ParScanWeakRefClosure* cl) : | |
689 DefNewGeneration::KeepAliveClosure(cl), _par_cl(cl) {} | |
690 | |
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691 template <class T> |
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692 void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop_work(T* p) { |
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693 #ifdef ASSERT |
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694 { |
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695 assert(!oopDesc::is_null(*p), "expected non-null ref"); |
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696 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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697 // We never expect to see a null reference being processed |
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698 // as a weak reference. |
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699 assert(obj->is_oop(), "expected an oop while scanning weak refs"); |
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700 } |
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701 #endif // ASSERT |
0 | 702 |
703 _par_cl->do_oop_nv(p); | |
704 | |
705 if (Universe::heap()->is_in_reserved(p)) { | |
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706 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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707 _rs->write_ref_field_gc_par(p, obj); |
0 | 708 } |
709 } | |
710 | |
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711 void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop(oop* p) { ParKeepAliveClosure::do_oop_work(p); } |
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712 void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop(narrowOop* p) { ParKeepAliveClosure::do_oop_work(p); } |
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713 |
0 | 714 // ParNewGeneration:: |
715 KeepAliveClosure::KeepAliveClosure(ScanWeakRefClosure* cl) : | |
716 DefNewGeneration::KeepAliveClosure(cl) {} | |
717 | |
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718 template <class T> |
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719 void /*ParNewGeneration::*/KeepAliveClosure::do_oop_work(T* p) { |
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720 #ifdef ASSERT |
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721 { |
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722 assert(!oopDesc::is_null(*p), "expected non-null ref"); |
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723 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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724 // We never expect to see a null reference being processed |
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725 // as a weak reference. |
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726 assert(obj->is_oop(), "expected an oop while scanning weak refs"); |
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727 } |
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728 #endif // ASSERT |
0 | 729 |
730 _cl->do_oop_nv(p); | |
731 | |
732 if (Universe::heap()->is_in_reserved(p)) { | |
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733 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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734 _rs->write_ref_field_gc_par(p, obj); |
0 | 735 } |
736 } | |
737 | |
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738 void /*ParNewGeneration::*/KeepAliveClosure::do_oop(oop* p) { KeepAliveClosure::do_oop_work(p); } |
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739 void /*ParNewGeneration::*/KeepAliveClosure::do_oop(narrowOop* p) { KeepAliveClosure::do_oop_work(p); } |
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740 |
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741 template <class T> void ScanClosureWithParBarrier::do_oop_work(T* p) { |
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742 T heap_oop = oopDesc::load_heap_oop(p); |
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743 if (!oopDesc::is_null(heap_oop)) { |
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744 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); |
0 | 745 if ((HeapWord*)obj < _boundary) { |
746 assert(!_g->to()->is_in_reserved(obj), "Scanning field twice?"); | |
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747 oop new_obj = obj->is_forwarded() |
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748 ? obj->forwardee() |
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749 : _g->DefNewGeneration::copy_to_survivor_space(obj); |
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750 oopDesc::encode_store_heap_oop_not_null(p, new_obj); |
0 | 751 } |
752 if (_gc_barrier) { | |
753 // If p points to a younger generation, mark the card. | |
754 if ((HeapWord*)obj < _gen_boundary) { | |
755 _rs->write_ref_field_gc_par(p, obj); | |
756 } | |
757 } | |
758 } | |
759 } | |
760 | |
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761 void ScanClosureWithParBarrier::do_oop(oop* p) { ScanClosureWithParBarrier::do_oop_work(p); } |
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762 void ScanClosureWithParBarrier::do_oop(narrowOop* p) { ScanClosureWithParBarrier::do_oop_work(p); } |
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763 |
0 | 764 class ParNewRefProcTaskProxy: public AbstractGangTask { |
765 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; | |
766 public: | |
767 ParNewRefProcTaskProxy(ProcessTask& task, ParNewGeneration& gen, | |
768 Generation& next_gen, | |
769 HeapWord* young_old_boundary, | |
770 ParScanThreadStateSet& state_set); | |
771 | |
772 private: | |
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773 virtual void work(uint worker_id); |
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774 virtual void set_for_termination(int active_workers) { |
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775 _state_set.terminator()->reset_for_reuse(active_workers); |
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776 } |
0 | 777 private: |
778 ParNewGeneration& _gen; | |
779 ProcessTask& _task; | |
780 Generation& _next_gen; | |
781 HeapWord* _young_old_boundary; | |
782 ParScanThreadStateSet& _state_set; | |
783 }; | |
784 | |
785 ParNewRefProcTaskProxy::ParNewRefProcTaskProxy( | |
786 ProcessTask& task, ParNewGeneration& gen, | |
787 Generation& next_gen, | |
788 HeapWord* young_old_boundary, | |
789 ParScanThreadStateSet& state_set) | |
790 : AbstractGangTask("ParNewGeneration parallel reference processing"), | |
791 _gen(gen), | |
792 _task(task), | |
793 _next_gen(next_gen), | |
794 _young_old_boundary(young_old_boundary), | |
795 _state_set(state_set) | |
796 { | |
797 } | |
798 | |
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799 void ParNewRefProcTaskProxy::work(uint worker_id) |
0 | 800 { |
801 ResourceMark rm; | |
802 HandleMark hm; | |
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803 ParScanThreadState& par_scan_state = _state_set.thread_state(worker_id); |
0 | 804 par_scan_state.set_young_old_boundary(_young_old_boundary); |
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805 _task.work(worker_id, par_scan_state.is_alive_closure(), |
0 | 806 par_scan_state.keep_alive_closure(), |
807 par_scan_state.evacuate_followers_closure()); | |
808 } | |
809 | |
810 class ParNewRefEnqueueTaskProxy: public AbstractGangTask { | |
811 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; | |
812 EnqueueTask& _task; | |
813 | |
814 public: | |
815 ParNewRefEnqueueTaskProxy(EnqueueTask& task) | |
816 : AbstractGangTask("ParNewGeneration parallel reference enqueue"), | |
817 _task(task) | |
818 { } | |
819 | |
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820 virtual void work(uint worker_id) |
0 | 821 { |
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822 _task.work(worker_id); |
0 | 823 } |
824 }; | |
825 | |
826 | |
827 void ParNewRefProcTaskExecutor::execute(ProcessTask& task) | |
828 { | |
829 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
830 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
831 "not a generational heap"); | |
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832 FlexibleWorkGang* workers = gch->workers(); |
0 | 833 assert(workers != NULL, "Need parallel worker threads."); |
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834 _state_set.reset(workers->active_workers(), _generation.promotion_failed()); |
0 | 835 ParNewRefProcTaskProxy rp_task(task, _generation, *_generation.next_gen(), |
836 _generation.reserved().end(), _state_set); | |
837 workers->run_task(&rp_task); | |
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838 _state_set.reset(0 /* bad value in debug if not reset */, |
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839 _generation.promotion_failed()); |
0 | 840 } |
841 | |
842 void ParNewRefProcTaskExecutor::execute(EnqueueTask& task) | |
843 { | |
844 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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845 FlexibleWorkGang* workers = gch->workers(); |
0 | 846 assert(workers != NULL, "Need parallel worker threads."); |
847 ParNewRefEnqueueTaskProxy enq_task(task); | |
848 workers->run_task(&enq_task); | |
849 } | |
850 | |
851 void ParNewRefProcTaskExecutor::set_single_threaded_mode() | |
852 { | |
853 _state_set.flush(); | |
854 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
855 gch->set_par_threads(0); // 0 ==> non-parallel. | |
856 gch->save_marks(); | |
857 } | |
858 | |
859 ScanClosureWithParBarrier:: | |
860 ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier) : | |
861 ScanClosure(g, gc_barrier) {} | |
862 | |
863 EvacuateFollowersClosureGeneral:: | |
864 EvacuateFollowersClosureGeneral(GenCollectedHeap* gch, int level, | |
865 OopsInGenClosure* cur, | |
866 OopsInGenClosure* older) : | |
867 _gch(gch), _level(level), | |
868 _scan_cur_or_nonheap(cur), _scan_older(older) | |
869 {} | |
870 | |
871 void EvacuateFollowersClosureGeneral::do_void() { | |
872 do { | |
873 // Beware: this call will lead to closure applications via virtual | |
874 // calls. | |
875 _gch->oop_since_save_marks_iterate(_level, | |
876 _scan_cur_or_nonheap, | |
877 _scan_older); | |
878 } while (!_gch->no_allocs_since_save_marks(_level)); | |
879 } | |
880 | |
881 | |
10405 | 882 // A Generation that does parallel young-gen collection. |
883 | |
0 | 884 bool ParNewGeneration::_avoid_promotion_undo = false; |
885 | |
10405 | 886 void ParNewGeneration::handle_promotion_failed(GenCollectedHeap* gch, ParScanThreadStateSet& thread_state_set, ParNewTracer& gc_tracer) { |
887 assert(_promo_failure_scan_stack.is_empty(), "post condition"); | |
888 _promo_failure_scan_stack.clear(true); // Clear cached segments. | |
889 | |
890 remove_forwarding_pointers(); | |
891 if (PrintGCDetails) { | |
892 gclog_or_tty->print(" (promotion failed)"); | |
893 } | |
894 // All the spaces are in play for mark-sweep. | |
895 swap_spaces(); // Make life simpler for CMS || rescan; see 6483690. | |
896 from()->set_next_compaction_space(to()); | |
897 gch->set_incremental_collection_failed(); | |
898 // Inform the next generation that a promotion failure occurred. | |
899 _next_gen->promotion_failure_occurred(); | |
900 | |
901 // Trace promotion failure in the parallel GC threads | |
902 thread_state_set.trace_promotion_failed(gc_tracer); | |
903 // Single threaded code may have reported promotion failure to the global state | |
904 if (_promotion_failed_info.has_failed()) { | |
905 gc_tracer.report_promotion_failed(_promotion_failed_info); | |
906 } | |
907 // Reset the PromotionFailureALot counters. | |
908 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();) | |
909 } | |
0 | 910 |
911 void ParNewGeneration::collect(bool full, | |
912 bool clear_all_soft_refs, | |
913 size_t size, | |
914 bool is_tlab) { | |
915 assert(full || size > 0, "otherwise we don't want to collect"); | |
10405 | 916 |
0 | 917 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
10405 | 918 |
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919 _gc_timer->register_gc_start(); |
10405 | 920 |
0 | 921 assert(gch->kind() == CollectedHeap::GenCollectedHeap, |
922 "not a CMS generational heap"); | |
923 AdaptiveSizePolicy* size_policy = gch->gen_policy()->size_policy(); | |
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924 FlexibleWorkGang* workers = gch->workers(); |
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925 assert(workers != NULL, "Need workgang for parallel work"); |
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926 int active_workers = |
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927 AdaptiveSizePolicy::calc_active_workers(workers->total_workers(), |
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928 workers->active_workers(), |
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929 Threads::number_of_non_daemon_threads()); |
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930 workers->set_active_workers(active_workers); |
0 | 931 assert(gch->n_gens() == 2, |
932 "Par collection currently only works with single older gen."); | |
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933 _next_gen = gch->next_gen(this); |
0 | 934 // Do we have to avoid promotion_undo? |
935 if (gch->collector_policy()->is_concurrent_mark_sweep_policy()) { | |
936 set_avoid_promotion_undo(true); | |
937 } | |
938 | |
10405 | 939 // If the next generation is too full to accommodate worst-case promotion |
0 | 940 // from this generation, pass on collection; let the next generation |
941 // do it. | |
942 if (!collection_attempt_is_safe()) { | |
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943 gch->set_incremental_collection_failed(); // slight lie, in that we did not even attempt one |
0 | 944 return; |
945 } | |
946 assert(to()->is_empty(), "Else not collection_attempt_is_safe"); | |
947 | |
10405 | 948 ParNewTracer gc_tracer; |
949 gc_tracer.report_gc_start(gch->gc_cause(), _gc_timer->gc_start()); | |
950 gch->trace_heap_before_gc(&gc_tracer); | |
951 | |
0 | 952 init_assuming_no_promotion_failure(); |
953 | |
954 if (UseAdaptiveSizePolicy) { | |
955 set_survivor_overflow(false); | |
956 size_policy->minor_collection_begin(); | |
957 } | |
958 | |
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959 GCTraceTime t1(GCCauseString("GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL, gc_tracer.gc_id()); |
0 | 960 // Capture heap used before collection (for printing). |
961 size_t gch_prev_used = gch->used(); | |
962 | |
963 SpecializationStats::clear(); | |
964 | |
965 age_table()->clear(); | |
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966 to()->clear(SpaceDecorator::Mangle); |
0 | 967 |
968 gch->save_marks(); | |
969 assert(workers != NULL, "Need parallel worker threads."); | |
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970 int n_workers = active_workers; |
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971 |
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972 // Set the correct parallelism (number of queues) in the reference processor |
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973 ref_processor()->set_active_mt_degree(n_workers); |
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974 |
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975 // Always set the terminator for the active number of workers |
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976 // because only those workers go through the termination protocol. |
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977 ParallelTaskTerminator _term(n_workers, task_queues()); |
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978 ParScanThreadStateSet thread_state_set(workers->active_workers(), |
0 | 979 *to(), *this, *_next_gen, *task_queues(), |
695 | 980 _overflow_stacks, desired_plab_sz(), _term); |
0 | 981 |
982 ParNewGenTask tsk(this, _next_gen, reserved().end(), &thread_state_set); | |
983 gch->set_par_threads(n_workers); | |
984 gch->rem_set()->prepare_for_younger_refs_iterate(true); | |
985 // It turns out that even when we're using 1 thread, doing the work in a | |
986 // separate thread causes wide variance in run times. We can't help this | |
987 // in the multi-threaded case, but we special-case n=1 here to get | |
988 // repeatable measurements of the 1-thread overhead of the parallel code. | |
989 if (n_workers > 1) { | |
989
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990 GenCollectedHeap::StrongRootsScope srs(gch); |
0 | 991 workers->run_task(&tsk); |
992 } else { | |
989
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993 GenCollectedHeap::StrongRootsScope srs(gch); |
0 | 994 tsk.work(0); |
995 } | |
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996 thread_state_set.reset(0 /* Bad value in debug if not reset */, |
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997 promotion_failed()); |
0 | 998 |
999 // Process (weak) reference objects found during scavenge. | |
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1000 ReferenceProcessor* rp = ref_processor(); |
0 | 1001 IsAliveClosure is_alive(this); |
1002 ScanWeakRefClosure scan_weak_ref(this); | |
1003 KeepAliveClosure keep_alive(&scan_weak_ref); | |
1004 ScanClosure scan_without_gc_barrier(this, false); | |
1005 ScanClosureWithParBarrier scan_with_gc_barrier(this, true); | |
1006 set_promo_failure_scan_stack_closure(&scan_without_gc_barrier); | |
1007 EvacuateFollowersClosureGeneral evacuate_followers(gch, _level, | |
1008 &scan_without_gc_barrier, &scan_with_gc_barrier); | |
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1009 rp->setup_policy(clear_all_soft_refs); |
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1010 // Can the mt_degree be set later (at run_task() time would be best)? |
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1011 rp->set_active_mt_degree(active_workers); |
10405 | 1012 ReferenceProcessorStats stats; |
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1013 if (rp->processing_is_mt()) { |
0 | 1014 ParNewRefProcTaskExecutor task_executor(*this, thread_state_set); |
10405 | 1015 stats = rp->process_discovered_references(&is_alive, &keep_alive, |
1016 &evacuate_followers, &task_executor, | |
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1017 _gc_timer, gc_tracer.gc_id()); |
0 | 1018 } else { |
1019 thread_state_set.flush(); | |
1020 gch->set_par_threads(0); // 0 ==> non-parallel. | |
1021 gch->save_marks(); | |
10405 | 1022 stats = rp->process_discovered_references(&is_alive, &keep_alive, |
1023 &evacuate_followers, NULL, | |
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1024 _gc_timer, gc_tracer.gc_id()); |
0 | 1025 } |
10405 | 1026 gc_tracer.report_gc_reference_stats(stats); |
0 | 1027 if (!promotion_failed()) { |
1028 // Swap the survivor spaces. | |
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1029 eden()->clear(SpaceDecorator::Mangle); |
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1030 from()->clear(SpaceDecorator::Mangle); |
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1031 if (ZapUnusedHeapArea) { |
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1032 // This is now done here because of the piece-meal mangling which |
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1033 // can check for valid mangling at intermediate points in the |
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1034 // collection(s). When a minor collection fails to collect |
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1035 // sufficient space resizing of the young generation can occur |
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1036 // an redistribute the spaces in the young generation. Mangle |
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1037 // here so that unzapped regions don't get distributed to |
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1038 // other spaces. |
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1039 to()->mangle_unused_area(); |
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1040 } |
0 | 1041 swap_spaces(); |
1042 | |
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1043 // A successful scavenge should restart the GC time limit count which is |
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1044 // for full GC's. |
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1045 size_policy->reset_gc_overhead_limit_count(); |
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1046 |
0 | 1047 assert(to()->is_empty(), "to space should be empty now"); |
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1048 |
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1049 adjust_desired_tenuring_threshold(); |
0 | 1050 } else { |
10405 | 1051 handle_promotion_failed(gch, thread_state_set, gc_tracer); |
0 | 1052 } |
1053 // set new iteration safe limit for the survivor spaces | |
1054 from()->set_concurrent_iteration_safe_limit(from()->top()); | |
1055 to()->set_concurrent_iteration_safe_limit(to()->top()); | |
1056 | |
1057 if (ResizePLAB) { | |
6819 | 1058 plab_stats()->adjust_desired_plab_sz(n_workers); |
0 | 1059 } |
1060 | |
1061 if (PrintGC && !PrintGCDetails) { | |
1062 gch->print_heap_change(gch_prev_used); | |
1063 } | |
1064 | |
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1065 if (PrintGCDetails && ParallelGCVerbose) { |
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1066 TASKQUEUE_STATS_ONLY(thread_state_set.print_termination_stats()); |
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1067 TASKQUEUE_STATS_ONLY(thread_state_set.print_taskqueue_stats()); |
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1068 } |
1710 | 1069 |
0 | 1070 if (UseAdaptiveSizePolicy) { |
1071 size_policy->minor_collection_end(gch->gc_cause()); | |
1072 size_policy->avg_survived()->sample(from()->used()); | |
1073 } | |
1074 | |
4911 | 1075 // We need to use a monotonically non-deccreasing time in ms |
1076 // or we will see time-warp warnings and os::javaTimeMillis() | |
1077 // does not guarantee monotonicity. | |
1078 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; | |
1079 update_time_of_last_gc(now); | |
0 | 1080 |
1081 SpecializationStats::print(); | |
1082 | |
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1083 rp->set_enqueuing_is_done(true); |
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1084 if (rp->processing_is_mt()) { |
0 | 1085 ParNewRefProcTaskExecutor task_executor(*this, thread_state_set); |
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1086 rp->enqueue_discovered_references(&task_executor); |
0 | 1087 } else { |
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1088 rp->enqueue_discovered_references(NULL); |
0 | 1089 } |
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1090 rp->verify_no_references_recorded(); |
10405 | 1091 |
1092 gch->trace_heap_after_gc(&gc_tracer); | |
1093 gc_tracer.report_tenuring_threshold(tenuring_threshold()); | |
1094 | |
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1095 _gc_timer->register_gc_end(); |
10405 | 1096 |
1097 gc_tracer.report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions()); | |
0 | 1098 } |
1099 | |
1100 static int sum; | |
1101 void ParNewGeneration::waste_some_time() { | |
1102 for (int i = 0; i < 100; i++) { | |
1103 sum += i; | |
1104 } | |
1105 } | |
1106 | |
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1107 static const oop ClaimedForwardPtr = cast_to_oop<intptr_t>(0x4); |
0 | 1108 |
1109 // Because of concurrency, there are times where an object for which | |
1110 // "is_forwarded()" is true contains an "interim" forwarding pointer | |
1111 // value. Such a value will soon be overwritten with a real value. | |
1112 // This method requires "obj" to have a forwarding pointer, and waits, if | |
1113 // necessary for a real one to be inserted, and returns it. | |
1114 | |
1115 oop ParNewGeneration::real_forwardee(oop obj) { | |
1116 oop forward_ptr = obj->forwardee(); | |
1117 if (forward_ptr != ClaimedForwardPtr) { | |
1118 return forward_ptr; | |
1119 } else { | |
1120 return real_forwardee_slow(obj); | |
1121 } | |
1122 } | |
1123 | |
1124 oop ParNewGeneration::real_forwardee_slow(oop obj) { | |
1125 // Spin-read if it is claimed but not yet written by another thread. | |
1126 oop forward_ptr = obj->forwardee(); | |
1127 while (forward_ptr == ClaimedForwardPtr) { | |
1128 waste_some_time(); | |
1129 assert(obj->is_forwarded(), "precondition"); | |
1130 forward_ptr = obj->forwardee(); | |
1131 } | |
1132 return forward_ptr; | |
1133 } | |
1134 | |
1135 #ifdef ASSERT | |
1136 bool ParNewGeneration::is_legal_forward_ptr(oop p) { | |
1137 return | |
1138 (_avoid_promotion_undo && p == ClaimedForwardPtr) | |
1139 || Universe::heap()->is_in_reserved(p); | |
1140 } | |
1141 #endif | |
1142 | |
1143 void ParNewGeneration::preserve_mark_if_necessary(oop obj, markOop m) { | |
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1144 if (m->must_be_preserved_for_promotion_failure(obj)) { |
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1145 // We should really have separate per-worker stacks, rather |
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1146 // than use locking of a common pair of stacks. |
0 | 1147 MutexLocker ml(ParGCRareEvent_lock); |
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1148 preserve_mark(obj, m); |
0 | 1149 } |
1150 } | |
1151 | |
1152 // Multiple GC threads may try to promote an object. If the object | |
1153 // is successfully promoted, a forwarding pointer will be installed in | |
1154 // the object in the young generation. This method claims the right | |
1155 // to install the forwarding pointer before it copies the object, | |
1156 // thus avoiding the need to undo the copy as in | |
1157 // copy_to_survivor_space_avoiding_with_undo. | |
1158 | |
1159 oop ParNewGeneration::copy_to_survivor_space_avoiding_promotion_undo( | |
1160 ParScanThreadState* par_scan_state, oop old, size_t sz, markOop m) { | |
1161 // In the sequential version, this assert also says that the object is | |
1162 // not forwarded. That might not be the case here. It is the case that | |
1163 // the caller observed it to be not forwarded at some time in the past. | |
1164 assert(is_in_reserved(old), "shouldn't be scavenging this oop"); | |
1165 | |
1166 // The sequential code read "old->age()" below. That doesn't work here, | |
1167 // since the age is in the mark word, and that might be overwritten with | |
1168 // a forwarding pointer by a parallel thread. So we must save the mark | |
1169 // word in a local and then analyze it. | |
1170 oopDesc dummyOld; | |
1171 dummyOld.set_mark(m); | |
1172 assert(!dummyOld.is_forwarded(), | |
1173 "should not be called with forwarding pointer mark word."); | |
1174 | |
1175 oop new_obj = NULL; | |
1176 oop forward_ptr; | |
1177 | |
1178 // Try allocating obj in to-space (unless too old) | |
1179 if (dummyOld.age() < tenuring_threshold()) { | |
1180 new_obj = (oop)par_scan_state->alloc_in_to_space(sz); | |
1181 if (new_obj == NULL) { | |
1182 set_survivor_overflow(true); | |
1183 } | |
1184 } | |
1185 | |
1186 if (new_obj == NULL) { | |
1187 // Either to-space is full or we decided to promote | |
1188 // try allocating obj tenured | |
1189 | |
1190 // Attempt to install a null forwarding pointer (atomically), | |
1191 // to claim the right to install the real forwarding pointer. | |
1192 forward_ptr = old->forward_to_atomic(ClaimedForwardPtr); | |
1193 if (forward_ptr != NULL) { | |
1194 // someone else beat us to it. | |
1195 return real_forwardee(old); | |
1196 } | |
1197 | |
1198 new_obj = _next_gen->par_promote(par_scan_state->thread_num(), | |
1199 old, m, sz); | |
1200 | |
1201 if (new_obj == NULL) { | |
1202 // promotion failed, forward to self | |
1203 _promotion_failed = true; | |
1204 new_obj = old; | |
1205 | |
1206 preserve_mark_if_necessary(old, m); | |
10405 | 1207 par_scan_state->register_promotion_failure(sz); |
0 | 1208 } |
1209 | |
1210 old->forward_to(new_obj); | |
1211 forward_ptr = NULL; | |
1212 } else { | |
1213 // Is in to-space; do copying ourselves. | |
1214 Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)new_obj, sz); | |
1215 forward_ptr = old->forward_to_atomic(new_obj); | |
1216 // Restore the mark word copied above. | |
1217 new_obj->set_mark(m); | |
1218 // Increment age if obj still in new generation | |
1219 new_obj->incr_age(); | |
1220 par_scan_state->age_table()->add(new_obj, sz); | |
1221 } | |
1222 assert(new_obj != NULL, "just checking"); | |
1223 | |
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1224 #ifndef PRODUCT |
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1225 // This code must come after the CAS test, or it will print incorrect |
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1226 // information. |
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1227 if (TraceScavenge) { |
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1228 gclog_or_tty->print_cr("{%s %s " PTR_FORMAT " -> " PTR_FORMAT " (%d)}", |
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1229 is_in_reserved(new_obj) ? "copying" : "tenuring", |
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1230 new_obj->klass()->internal_name(), (void *)old, (void *)new_obj, new_obj->size()); |
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1231 } |
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1232 #endif |
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1233 |
0 | 1234 if (forward_ptr == NULL) { |
1235 oop obj_to_push = new_obj; | |
1236 if (par_scan_state->should_be_partially_scanned(obj_to_push, old)) { | |
1237 // Length field used as index of next element to be scanned. | |
1238 // Real length can be obtained from real_forwardee() | |
1239 arrayOop(old)->set_length(0); | |
1240 obj_to_push = old; | |
1241 assert(obj_to_push->is_forwarded() && obj_to_push->forwardee() != obj_to_push, | |
1242 "push forwarded object"); | |
1243 } | |
1244 // Push it on one of the queues of to-be-scanned objects. | |
534 | 1245 bool simulate_overflow = false; |
1246 NOT_PRODUCT( | |
1247 if (ParGCWorkQueueOverflowALot && should_simulate_overflow()) { | |
1248 // simulate a stack overflow | |
1249 simulate_overflow = true; | |
1250 } | |
1251 ) | |
1252 if (simulate_overflow || !par_scan_state->work_queue()->push(obj_to_push)) { | |
0 | 1253 // Add stats for overflow pushes. |
1254 if (Verbose && PrintGCDetails) { | |
1255 gclog_or_tty->print("queue overflow!\n"); | |
1256 } | |
534 | 1257 push_on_overflow_list(old, par_scan_state); |
1710 | 1258 TASKQUEUE_STATS_ONLY(par_scan_state->taskqueue_stats().record_overflow(0)); |
0 | 1259 } |
1260 | |
1261 return new_obj; | |
1262 } | |
1263 | |
1264 // Oops. Someone beat us to it. Undo the allocation. Where did we | |
1265 // allocate it? | |
1266 if (is_in_reserved(new_obj)) { | |
1267 // Must be in to_space. | |
1268 assert(to()->is_in_reserved(new_obj), "Checking"); | |
1269 if (forward_ptr == ClaimedForwardPtr) { | |
1270 // Wait to get the real forwarding pointer value. | |
1271 forward_ptr = real_forwardee(old); | |
1272 } | |
1273 par_scan_state->undo_alloc_in_to_space((HeapWord*)new_obj, sz); | |
1274 } | |
1275 | |
1276 return forward_ptr; | |
1277 } | |
1278 | |
1279 | |
1280 // Multiple GC threads may try to promote the same object. If two | |
1281 // or more GC threads copy the object, only one wins the race to install | |
1282 // the forwarding pointer. The other threads have to undo their copy. | |
1283 | |
1284 oop ParNewGeneration::copy_to_survivor_space_with_undo( | |
1285 ParScanThreadState* par_scan_state, oop old, size_t sz, markOop m) { | |
1286 | |
1287 // In the sequential version, this assert also says that the object is | |
1288 // not forwarded. That might not be the case here. It is the case that | |
1289 // the caller observed it to be not forwarded at some time in the past. | |
1290 assert(is_in_reserved(old), "shouldn't be scavenging this oop"); | |
1291 | |
1292 // The sequential code read "old->age()" below. That doesn't work here, | |
1293 // since the age is in the mark word, and that might be overwritten with | |
1294 // a forwarding pointer by a parallel thread. So we must save the mark | |
1295 // word here, install it in a local oopDesc, and then analyze it. | |
1296 oopDesc dummyOld; | |
1297 dummyOld.set_mark(m); | |
1298 assert(!dummyOld.is_forwarded(), | |
1299 "should not be called with forwarding pointer mark word."); | |
1300 | |
1301 bool failed_to_promote = false; | |
1302 oop new_obj = NULL; | |
1303 oop forward_ptr; | |
1304 | |
1305 // Try allocating obj in to-space (unless too old) | |
1306 if (dummyOld.age() < tenuring_threshold()) { | |
1307 new_obj = (oop)par_scan_state->alloc_in_to_space(sz); | |
1308 if (new_obj == NULL) { | |
1309 set_survivor_overflow(true); | |
1310 } | |
1311 } | |
1312 | |
1313 if (new_obj == NULL) { | |
1314 // Either to-space is full or we decided to promote | |
1315 // try allocating obj tenured | |
1316 new_obj = _next_gen->par_promote(par_scan_state->thread_num(), | |
1317 old, m, sz); | |
1318 | |
1319 if (new_obj == NULL) { | |
1320 // promotion failed, forward to self | |
1321 forward_ptr = old->forward_to_atomic(old); | |
1322 new_obj = old; | |
1323 | |
1324 if (forward_ptr != NULL) { | |
1325 return forward_ptr; // someone else succeeded | |
1326 } | |
1327 | |
1328 _promotion_failed = true; | |
1329 failed_to_promote = true; | |
1330 | |
1331 preserve_mark_if_necessary(old, m); | |
10405 | 1332 par_scan_state->register_promotion_failure(sz); |
0 | 1333 } |
1334 } else { | |
1335 // Is in to-space; do copying ourselves. | |
1336 Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)new_obj, sz); | |
1337 // Restore the mark word copied above. | |
1338 new_obj->set_mark(m); | |
1339 // Increment age if new_obj still in new generation | |
1340 new_obj->incr_age(); | |
1341 par_scan_state->age_table()->add(new_obj, sz); | |
1342 } | |
1343 assert(new_obj != NULL, "just checking"); | |
1344 | |
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1345 #ifndef PRODUCT |
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1346 // This code must come after the CAS test, or it will print incorrect |
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1347 // information. |
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1348 if (TraceScavenge) { |
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1349 gclog_or_tty->print_cr("{%s %s " PTR_FORMAT " -> " PTR_FORMAT " (%d)}", |
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1350 is_in_reserved(new_obj) ? "copying" : "tenuring", |
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1351 new_obj->klass()->internal_name(), (void *)old, (void *)new_obj, new_obj->size()); |
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1352 } |
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1353 #endif |
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1354 |
0 | 1355 // Now attempt to install the forwarding pointer (atomically). |
1356 // We have to copy the mark word before overwriting with forwarding | |
1357 // ptr, so we can restore it below in the copy. | |
1358 if (!failed_to_promote) { | |
1359 forward_ptr = old->forward_to_atomic(new_obj); | |
1360 } | |
1361 | |
1362 if (forward_ptr == NULL) { | |
1363 oop obj_to_push = new_obj; | |
1364 if (par_scan_state->should_be_partially_scanned(obj_to_push, old)) { | |
1365 // Length field used as index of next element to be scanned. | |
1366 // Real length can be obtained from real_forwardee() | |
1367 arrayOop(old)->set_length(0); | |
1368 obj_to_push = old; | |
1369 assert(obj_to_push->is_forwarded() && obj_to_push->forwardee() != obj_to_push, | |
1370 "push forwarded object"); | |
1371 } | |
1372 // Push it on one of the queues of to-be-scanned objects. | |
534 | 1373 bool simulate_overflow = false; |
1374 NOT_PRODUCT( | |
1375 if (ParGCWorkQueueOverflowALot && should_simulate_overflow()) { | |
1376 // simulate a stack overflow | |
1377 simulate_overflow = true; | |
1378 } | |
1379 ) | |
1380 if (simulate_overflow || !par_scan_state->work_queue()->push(obj_to_push)) { | |
0 | 1381 // Add stats for overflow pushes. |
534 | 1382 push_on_overflow_list(old, par_scan_state); |
1710 | 1383 TASKQUEUE_STATS_ONLY(par_scan_state->taskqueue_stats().record_overflow(0)); |
0 | 1384 } |
1385 | |
1386 return new_obj; | |
1387 } | |
1388 | |
1389 // Oops. Someone beat us to it. Undo the allocation. Where did we | |
1390 // allocate it? | |
1391 if (is_in_reserved(new_obj)) { | |
1392 // Must be in to_space. | |
1393 assert(to()->is_in_reserved(new_obj), "Checking"); | |
1394 par_scan_state->undo_alloc_in_to_space((HeapWord*)new_obj, sz); | |
1395 } else { | |
1396 assert(!_avoid_promotion_undo, "Should not be here if avoiding."); | |
1397 _next_gen->par_promote_alloc_undo(par_scan_state->thread_num(), | |
1398 (HeapWord*)new_obj, sz); | |
1399 } | |
1400 | |
1401 return forward_ptr; | |
1402 } | |
1403 | |
534 | 1404 #ifndef PRODUCT |
1405 // It's OK to call this multi-threaded; the worst thing | |
1406 // that can happen is that we'll get a bunch of closely | |
1407 // spaced simulated oveflows, but that's OK, in fact | |
1408 // probably good as it would exercise the overflow code | |
1409 // under contention. | |
1410 bool ParNewGeneration::should_simulate_overflow() { | |
1411 if (_overflow_counter-- <= 0) { // just being defensive | |
1412 _overflow_counter = ParGCWorkQueueOverflowInterval; | |
1413 return true; | |
1414 } else { | |
1415 return false; | |
1416 } | |
1417 } | |
1418 #endif | |
1419 | |
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1420 // In case we are using compressed oops, we need to be careful. |
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1421 // If the object being pushed is an object array, then its length |
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1422 // field keeps track of the "grey boundary" at which the next |
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1423 // incremental scan will be done (see ParGCArrayScanChunk). |
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1424 // When using compressed oops, this length field is kept in the |
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1425 // lower 32 bits of the erstwhile klass word and cannot be used |
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1426 // for the overflow chaining pointer (OCP below). As such the OCP |
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1427 // would itself need to be compressed into the top 32-bits in this |
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1428 // case. Unfortunately, see below, in the event that we have a |
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1429 // promotion failure, the node to be pushed on the list can be |
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1430 // outside of the Java heap, so the heap-based pointer compression |
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1431 // would not work (we would have potential aliasing between C-heap |
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1432 // and Java-heap pointers). For this reason, when using compressed |
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1433 // oops, we simply use a worker-thread-local, non-shared overflow |
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1434 // list in the form of a growable array, with a slightly different |
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1435 // overflow stack draining strategy. If/when we start using fat |
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1436 // stacks here, we can go back to using (fat) pointer chains |
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1437 // (although some performance comparisons would be useful since |
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1438 // single global lists have their own performance disadvantages |
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1439 // as we were made painfully aware not long ago, see 6786503). |
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1440 #define BUSY (cast_to_oop<intptr_t>(0x1aff1aff)) |
534 | 1441 void ParNewGeneration::push_on_overflow_list(oop from_space_obj, ParScanThreadState* par_scan_state) { |
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1442 assert(is_in_reserved(from_space_obj), "Should be from this generation"); |
695 | 1443 if (ParGCUseLocalOverflow) { |
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1444 // In the case of compressed oops, we use a private, not-shared |
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1445 // overflow stack. |
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1446 par_scan_state->push_on_overflow_stack(from_space_obj); |
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1447 } else { |
695 | 1448 assert(!UseCompressedOops, "Error"); |
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1449 // if the object has been forwarded to itself, then we cannot |
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1450 // use the klass pointer for the linked list. Instead we have |
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1451 // to allocate an oopDesc in the C-Heap and use that for the linked list. |
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1452 // XXX This is horribly inefficient when a promotion failure occurs |
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1453 // and should be fixed. XXX FIX ME !!! |
534 | 1454 #ifndef PRODUCT |
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1455 Atomic::inc_ptr(&_num_par_pushes); |
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1456 assert(_num_par_pushes > 0, "Tautology"); |
534 | 1457 #endif |
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1458 if (from_space_obj->forwardee() == from_space_obj) { |
6197 | 1459 oopDesc* listhead = NEW_C_HEAP_ARRAY(oopDesc, 1, mtGC); |
679
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1460 listhead->forward_to(from_space_obj); |
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1461 from_space_obj = listhead; |
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1462 } |
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1463 oop observed_overflow_list = _overflow_list; |
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1464 oop cur_overflow_list; |
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1465 do { |
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1466 cur_overflow_list = observed_overflow_list; |
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1467 if (cur_overflow_list != BUSY) { |
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1468 from_space_obj->set_klass_to_list_ptr(cur_overflow_list); |
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1469 } else { |
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1470 from_space_obj->set_klass_to_list_ptr(NULL); |
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1471 } |
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1472 observed_overflow_list = |
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1473 (oop)Atomic::cmpxchg_ptr(from_space_obj, &_overflow_list, cur_overflow_list); |
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1474 } while (cur_overflow_list != observed_overflow_list); |
0 | 1475 } |
1476 } | |
1477 | |
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1478 bool ParNewGeneration::take_from_overflow_list(ParScanThreadState* par_scan_state) { |
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1479 bool res; |
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1480 |
695 | 1481 if (ParGCUseLocalOverflow) { |
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1482 res = par_scan_state->take_from_overflow_stack(); |
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1483 } else { |
695 | 1484 assert(!UseCompressedOops, "Error"); |
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1485 res = take_from_overflow_list_work(par_scan_state); |
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1486 } |
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1487 return res; |
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1488 } |
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1489 |
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1490 |
534 | 1491 // *NOTE*: The overflow list manipulation code here and |
1492 // in CMSCollector:: are very similar in shape, | |
1493 // except that in the CMS case we thread the objects | |
1494 // directly into the list via their mark word, and do | |
1495 // not need to deal with special cases below related | |
1496 // to chunking of object arrays and promotion failure | |
1497 // handling. | |
1498 // CR 6797058 has been filed to attempt consolidation of | |
1499 // the common code. | |
1500 // Because of the common code, if you make any changes in | |
1501 // the code below, please check the CMS version to see if | |
1502 // similar changes might be needed. | |
1503 // See CMSCollector::par_take_from_overflow_list() for | |
1504 // more extensive documentation comments. | |
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1505 bool ParNewGeneration::take_from_overflow_list_work(ParScanThreadState* par_scan_state) { |
0 | 1506 ObjToScanQueue* work_q = par_scan_state->work_queue(); |
1507 // How many to take? | |
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1508 size_t objsFromOverflow = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
534 | 1509 (size_t)ParGCDesiredObjsFromOverflowList); |
0 | 1510 |
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1511 assert(!UseCompressedOops, "Error"); |
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1512 assert(par_scan_state->overflow_stack() == NULL, "Error"); |
0 | 1513 if (_overflow_list == NULL) return false; |
1514 | |
1515 // Otherwise, there was something there; try claiming the list. | |
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1516 oop prefix = cast_to_oop(Atomic::xchg_ptr(BUSY, &_overflow_list)); |
534 | 1517 // Trim off a prefix of at most objsFromOverflow items |
1518 Thread* tid = Thread::current(); | |
1519 size_t spin_count = (size_t)ParallelGCThreads; | |
1520 size_t sleep_time_millis = MAX2((size_t)1, objsFromOverflow/100); | |
1521 for (size_t spin = 0; prefix == BUSY && spin < spin_count; spin++) { | |
1522 // someone grabbed it before we did ... | |
1523 // ... we spin for a short while... | |
1524 os::sleep(tid, sleep_time_millis, false); | |
1525 if (_overflow_list == NULL) { | |
1526 // nothing left to take | |
1527 return false; | |
1528 } else if (_overflow_list != BUSY) { | |
1529 // try and grab the prefix | |
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1530 prefix = cast_to_oop(Atomic::xchg_ptr(BUSY, &_overflow_list)); |
534 | 1531 } |
0 | 1532 } |
534 | 1533 if (prefix == NULL || prefix == BUSY) { |
1534 // Nothing to take or waited long enough | |
1535 if (prefix == NULL) { | |
1536 // Write back the NULL in case we overwrote it with BUSY above | |
1537 // and it is still the same value. | |
1538 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
1539 } | |
1540 return false; | |
1541 } | |
1542 assert(prefix != NULL && prefix != BUSY, "Error"); | |
1543 size_t i = 1; | |
0 | 1544 oop cur = prefix; |
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1545 while (i < objsFromOverflow && cur->klass_or_null() != NULL) { |
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1546 i++; cur = cur->list_ptr_from_klass(); |
0 | 1547 } |
1548 | |
1549 // Reattach remaining (suffix) to overflow list | |
534 | 1550 if (cur->klass_or_null() == NULL) { |
1551 // Write back the NULL in lieu of the BUSY we wrote | |
1552 // above and it is still the same value. | |
1553 if (_overflow_list == BUSY) { | |
1554 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
0 | 1555 } |
534 | 1556 } else { |
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1557 assert(cur->klass_or_null() != (Klass*)(address)BUSY, "Error"); |
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1558 oop suffix = cur->list_ptr_from_klass(); // suffix will be put back on global list |
534 | 1559 cur->set_klass_to_list_ptr(NULL); // break off suffix |
1560 // It's possible that the list is still in the empty(busy) state | |
1561 // we left it in a short while ago; in that case we may be | |
1562 // able to place back the suffix. | |
1563 oop observed_overflow_list = _overflow_list; | |
1564 oop cur_overflow_list = observed_overflow_list; | |
1565 bool attached = false; | |
1566 while (observed_overflow_list == BUSY || observed_overflow_list == NULL) { | |
1567 observed_overflow_list = | |
1568 (oop) Atomic::cmpxchg_ptr(suffix, &_overflow_list, cur_overflow_list); | |
1569 if (cur_overflow_list == observed_overflow_list) { | |
1570 attached = true; | |
1571 break; | |
1572 } else cur_overflow_list = observed_overflow_list; | |
1573 } | |
1574 if (!attached) { | |
1575 // Too bad, someone else got in in between; we'll need to do a splice. | |
1576 // Find the last item of suffix list | |
1577 oop last = suffix; | |
1578 while (last->klass_or_null() != NULL) { | |
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1579 last = last->list_ptr_from_klass(); |
534 | 1580 } |
1581 // Atomically prepend suffix to current overflow list | |
1582 observed_overflow_list = _overflow_list; | |
1583 do { | |
1584 cur_overflow_list = observed_overflow_list; | |
1585 if (cur_overflow_list != BUSY) { | |
1586 // Do the splice ... | |
1587 last->set_klass_to_list_ptr(cur_overflow_list); | |
1588 } else { // cur_overflow_list == BUSY | |
1589 last->set_klass_to_list_ptr(NULL); | |
1590 } | |
1591 observed_overflow_list = | |
1592 (oop)Atomic::cmpxchg_ptr(suffix, &_overflow_list, cur_overflow_list); | |
1593 } while (cur_overflow_list != observed_overflow_list); | |
0 | 1594 } |
1595 } | |
1596 | |
1597 // Push objects on prefix list onto this thread's work queue | |
534 | 1598 assert(prefix != NULL && prefix != BUSY, "program logic"); |
0 | 1599 cur = prefix; |
534 | 1600 ssize_t n = 0; |
0 | 1601 while (cur != NULL) { |
1602 oop obj_to_push = cur->forwardee(); | |
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1603 oop next = cur->list_ptr_from_klass(); |
0 | 1604 cur->set_klass(obj_to_push->klass()); |
534 | 1605 // This may be an array object that is self-forwarded. In that case, the list pointer |
1606 // space, cur, is not in the Java heap, but rather in the C-heap and should be freed. | |
1607 if (!is_in_reserved(cur)) { | |
1608 // This can become a scaling bottleneck when there is work queue overflow coincident | |
1609 // with promotion failure. | |
1610 oopDesc* f = cur; | |
6197 | 1611 FREE_C_HEAP_ARRAY(oopDesc, f, mtGC); |
534 | 1612 } else if (par_scan_state->should_be_partially_scanned(obj_to_push, cur)) { |
0 | 1613 assert(arrayOop(cur)->length() == 0, "entire array remaining to be scanned"); |
534 | 1614 obj_to_push = cur; |
0 | 1615 } |
534 | 1616 bool ok = work_q->push(obj_to_push); |
1617 assert(ok, "Should have succeeded"); | |
0 | 1618 cur = next; |
1619 n++; | |
1620 } | |
1710 | 1621 TASKQUEUE_STATS_ONLY(par_scan_state->note_overflow_refill(n)); |
534 | 1622 #ifndef PRODUCT |
1623 assert(_num_par_pushes >= n, "Too many pops?"); | |
1624 Atomic::add_ptr(-(intptr_t)n, &_num_par_pushes); | |
1625 #endif | |
0 | 1626 return true; |
1627 } | |
534 | 1628 #undef BUSY |
0 | 1629 |
10405 | 1630 void ParNewGeneration::ref_processor_init() { |
0 | 1631 if (_ref_processor == NULL) { |
1632 // Allocate and initialize a reference processor | |
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1633 _ref_processor = |
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1634 new ReferenceProcessor(_reserved, // span |
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1635 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing |
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1636 (int) ParallelGCThreads, // mt processing degree |
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1637 refs_discovery_is_mt(), // mt discovery |
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1638 (int) ParallelGCThreads, // mt discovery degree |
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1639 refs_discovery_is_atomic(), // atomic_discovery |
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1640 NULL); // is_alive_non_header |
0 | 1641 } |
1642 } | |
1643 | |
1644 const char* ParNewGeneration::name() const { | |
1645 return "par new generation"; | |
1646 } |