1 /*
2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
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 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc_implementation/parallelScavenge/adjoiningGenerations.hpp"
27 #include "gc_implementation/parallelScavenge/adjoiningVirtualSpaces.hpp"
28 #include "gc_implementation/parallelScavenge/cardTableExtension.hpp"
29 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp"
30 #include "gc_implementation/parallelScavenge/generationSizer.hpp"
31 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.inline.hpp"
32 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
33 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp"
34 #include "gc_implementation/parallelScavenge/psParallelCompact.hpp"
35 #include "gc_implementation/parallelScavenge/psPromotionManager.hpp"
36 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
37 #include "gc_implementation/parallelScavenge/vmPSOperations.hpp"
38 #include "gc_implementation/shared/gcHeapSummary.hpp"
39 #include "gc_implementation/shared/gcWhen.hpp"
40 #include "memory/gcLocker.inline.hpp"
41 #include "oops/oop.inline.hpp"
42 #include "runtime/handles.inline.hpp"
43 #include "runtime/java.hpp"
44 #include "runtime/vmThread.hpp"
45 #include "services/memTracker.hpp"
46 #include "utilities/vmError.hpp"
47
48 PSYoungGen* ParallelScavengeHeap::_young_gen = NULL;
49 PSOldGen* ParallelScavengeHeap::_old_gen = NULL;
50 PSPermGen* ParallelScavengeHeap::_perm_gen = NULL;
51 PSAdaptiveSizePolicy* ParallelScavengeHeap::_size_policy = NULL;
52 PSGCAdaptivePolicyCounters* ParallelScavengeHeap::_gc_policy_counters = NULL;
53 ParallelScavengeHeap* ParallelScavengeHeap::_psh = NULL;
54 GCTaskManager* ParallelScavengeHeap::_gc_task_manager = NULL;
55
56 static void trace_gen_sizes(const char* const str,
57 size_t pg_min, size_t pg_max,
58 size_t og_min, size_t og_max,
59 size_t yg_min, size_t yg_max)
60 {
61 if (TracePageSizes) {
62 tty->print_cr("%s: " SIZE_FORMAT "," SIZE_FORMAT " "
63 SIZE_FORMAT "," SIZE_FORMAT " "
64 SIZE_FORMAT "," SIZE_FORMAT " "
65 SIZE_FORMAT,
66 str, pg_min / K, pg_max / K,
67 og_min / K, og_max / K,
68 yg_min / K, yg_max / K,
69 (pg_max + og_max + yg_max) / K);
70 }
71 }
72
73 jint ParallelScavengeHeap::initialize() {
74 CollectedHeap::pre_initialize();
75
76 // Cannot be initialized until after the flags are parsed
77 // GenerationSizer flag_parser;
78 _collector_policy = new GenerationSizer();
79
80 size_t yg_min_size = _collector_policy->min_young_gen_size();
81 size_t yg_max_size = _collector_policy->max_young_gen_size();
82 size_t og_min_size = _collector_policy->min_old_gen_size();
83 size_t og_max_size = _collector_policy->max_old_gen_size();
84 // Why isn't there a min_perm_gen_size()?
85 size_t pg_min_size = _collector_policy->perm_gen_size();
86 size_t pg_max_size = _collector_policy->max_perm_gen_size();
87
88 trace_gen_sizes("ps heap raw",
89 pg_min_size, pg_max_size,
90 og_min_size, og_max_size,
91 yg_min_size, yg_max_size);
92
93 // The ReservedSpace ctor used below requires that the page size for the perm
94 // gen is <= the page size for the rest of the heap (young + old gens).
95 const size_t og_page_sz = os::page_size_for_region(yg_min_size + og_min_size,
96 yg_max_size + og_max_size,
97 8);
98 const size_t pg_page_sz = MIN2(os::page_size_for_region(pg_min_size,
99 pg_max_size, 16),
100 og_page_sz);
101
102 const size_t pg_align = set_alignment(_perm_gen_alignment, pg_page_sz);
103 const size_t og_align = set_alignment(_old_gen_alignment, og_page_sz);
104 const size_t yg_align = set_alignment(_young_gen_alignment, og_page_sz);
105
106 // Update sizes to reflect the selected page size(s).
107 //
108 // NEEDS_CLEANUP. The default TwoGenerationCollectorPolicy uses NewRatio; it
109 // should check UseAdaptiveSizePolicy. Changes from generationSizer could
110 // move to the common code.
111 yg_min_size = align_size_up(yg_min_size, yg_align);
112 yg_max_size = align_size_up(yg_max_size, yg_align);
113 size_t yg_cur_size =
114 align_size_up(_collector_policy->young_gen_size(), yg_align);
115 yg_cur_size = MAX2(yg_cur_size, yg_min_size);
116
117 og_min_size = align_size_up(og_min_size, og_align);
118 // Align old gen size down to preserve specified heap size.
119 assert(og_align == yg_align, "sanity");
120 og_max_size = align_size_down(og_max_size, og_align);
121 og_max_size = MAX2(og_max_size, og_min_size);
122 size_t og_cur_size =
123 align_size_down(_collector_policy->old_gen_size(), og_align);
124 og_cur_size = MAX2(og_cur_size, og_min_size);
125
126 pg_min_size = align_size_up(pg_min_size, pg_align);
127 pg_max_size = align_size_up(pg_max_size, pg_align);
128 size_t pg_cur_size = pg_min_size;
129
130 trace_gen_sizes("ps heap rnd",
131 pg_min_size, pg_max_size,
132 og_min_size, og_max_size,
133 yg_min_size, yg_max_size);
134
135 size_t total_reserved = 0;
136
137 total_reserved = add_and_check_overflow(total_reserved, pg_max_size);
138 total_reserved = add_and_check_overflow(total_reserved, og_max_size);
139 total_reserved = add_and_check_overflow(total_reserved, yg_max_size);
140
141 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
142
143 // The main part of the heap (old gen + young gen) can often use a larger page
144 // size than is needed or wanted for the perm gen. Use the "compound
145 // alignment" ReservedSpace ctor to avoid having to use the same page size for
146 // all gens.
147
148 ReservedHeapSpace heap_rs(pg_max_size, pg_align, og_max_size + yg_max_size,
149 og_align, addr);
150
151 if (UseCompressedOops) {
152 if (addr != NULL && !heap_rs.is_reserved()) {
153 // Failed to reserve at specified address - the requested memory
154 // region is taken already, for example, by 'java' launcher.
155 // Try again to reserver heap higher.
156 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
157 ReservedHeapSpace heap_rs0(pg_max_size, pg_align, og_max_size + yg_max_size,
158 og_align, addr);
159 if (addr != NULL && !heap_rs0.is_reserved()) {
160 // Failed to reserve at specified address again - give up.
161 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
162 assert(addr == NULL, "");
163 ReservedHeapSpace heap_rs1(pg_max_size, pg_align, og_max_size + yg_max_size,
164 og_align, addr);
165 heap_rs = heap_rs1;
166 } else {
167 heap_rs = heap_rs0;
168 }
169 }
170 }
171
172 MemTracker::record_virtual_memory_type((address)heap_rs.base(), mtJavaHeap);
173
174 os::trace_page_sizes("ps perm", pg_min_size, pg_max_size, pg_page_sz,
175 heap_rs.base(), pg_max_size);
176 os::trace_page_sizes("ps main", og_min_size + yg_min_size,
177 og_max_size + yg_max_size, og_page_sz,
178 heap_rs.base() + pg_max_size,
179 heap_rs.size() - pg_max_size);
180 if (!heap_rs.is_reserved()) {
181 vm_shutdown_during_initialization(
182 "Could not reserve enough space for object heap");
183 return JNI_ENOMEM;
184 }
185
186 _reserved = MemRegion((HeapWord*)heap_rs.base(),
187 (HeapWord*)(heap_rs.base() + heap_rs.size()));
188
189 CardTableExtension* const barrier_set = new CardTableExtension(_reserved, 3);
190 _barrier_set = barrier_set;
191 oopDesc::set_bs(_barrier_set);
192 if (_barrier_set == NULL) {
193 vm_shutdown_during_initialization(
194 "Could not reserve enough space for barrier set");
195 return JNI_ENOMEM;
196 }
197
198 // Initial young gen size is 4 Mb
199 //
200 // XXX - what about flag_parser.young_gen_size()?
201 const size_t init_young_size = align_size_up(4 * M, yg_align);
202 yg_cur_size = MAX2(MIN2(init_young_size, yg_max_size), yg_cur_size);
203
204 // Split the reserved space into perm gen and the main heap (everything else).
205 // The main heap uses a different alignment.
206 ReservedSpace perm_rs = heap_rs.first_part(pg_max_size);
207 ReservedSpace main_rs = heap_rs.last_part(pg_max_size, og_align);
208
209 // Make up the generations
210 // Calculate the maximum size that a generation can grow. This
211 // includes growth into the other generation. Note that the
212 // parameter _max_gen_size is kept as the maximum
213 // size of the generation as the boundaries currently stand.
214 // _max_gen_size is still used as that value.
215 double max_gc_pause_sec = ((double) MaxGCPauseMillis)/1000.0;
216 double max_gc_minor_pause_sec = ((double) MaxGCMinorPauseMillis)/1000.0;
217
218 _gens = new AdjoiningGenerations(main_rs,
219 og_cur_size,
220 og_min_size,
221 og_max_size,
222 yg_cur_size,
223 yg_min_size,
224 yg_max_size,
225 yg_align);
226
227 _old_gen = _gens->old_gen();
228 _young_gen = _gens->young_gen();
229
230 const size_t eden_capacity = _young_gen->eden_space()->capacity_in_bytes();
231 const size_t old_capacity = _old_gen->capacity_in_bytes();
232 const size_t initial_promo_size = MIN2(eden_capacity, old_capacity);
233 _size_policy =
234 new PSAdaptiveSizePolicy(eden_capacity,
235 initial_promo_size,
236 young_gen()->to_space()->capacity_in_bytes(),
237 intra_heap_alignment(),
238 max_gc_pause_sec,
239 max_gc_minor_pause_sec,
240 GCTimeRatio
241 );
242
243 _perm_gen = new PSPermGen(perm_rs,
244 pg_align,
245 pg_cur_size,
246 pg_cur_size,
247 pg_max_size,
248 "perm", 2);
249
250 assert(!UseAdaptiveGCBoundary ||
251 (old_gen()->virtual_space()->high_boundary() ==
252 young_gen()->virtual_space()->low_boundary()),
253 "Boundaries must meet");
254 // initialize the policy counters - 2 collectors, 3 generations
255 _gc_policy_counters =
256 new PSGCAdaptivePolicyCounters("ParScav:MSC", 2, 3, _size_policy);
257 _psh = this;
258
259 // Set up the GCTaskManager
260 _gc_task_manager = GCTaskManager::create(ParallelGCThreads);
261
262 if (UseParallelOldGC && !PSParallelCompact::initialize()) {
263 return JNI_ENOMEM;
264 }
265
266 return JNI_OK;
267 }
268
269 void ParallelScavengeHeap::post_initialize() {
270 // Need to init the tenuring threshold
271 PSScavenge::initialize();
272 if (UseParallelOldGC) {
273 PSParallelCompact::post_initialize();
274 } else {
275 PSMarkSweep::initialize();
276 }
277 PSPromotionManager::initialize();
278 }
279
280 void ParallelScavengeHeap::update_counters() {
281 young_gen()->update_counters();
282 old_gen()->update_counters();
283 perm_gen()->update_counters();
284 }
285
286 size_t ParallelScavengeHeap::capacity() const {
287 size_t value = young_gen()->capacity_in_bytes() + old_gen()->capacity_in_bytes();
288 return value;
289 }
290
291 size_t ParallelScavengeHeap::used() const {
292 size_t value = young_gen()->used_in_bytes() + old_gen()->used_in_bytes();
293 return value;
294 }
295
296 bool ParallelScavengeHeap::is_maximal_no_gc() const {
297 return old_gen()->is_maximal_no_gc() && young_gen()->is_maximal_no_gc();
298 }
299
300
301 size_t ParallelScavengeHeap::permanent_capacity() const {
302 return perm_gen()->capacity_in_bytes();
303 }
304
305 size_t ParallelScavengeHeap::permanent_used() const {
306 return perm_gen()->used_in_bytes();
307 }
308
309 size_t ParallelScavengeHeap::max_capacity() const {
310 size_t estimated = reserved_region().byte_size();
311 estimated -= perm_gen()->reserved().byte_size();
312 if (UseAdaptiveSizePolicy) {
313 estimated -= _size_policy->max_survivor_size(young_gen()->max_size());
314 } else {
315 estimated -= young_gen()->to_space()->capacity_in_bytes();
316 }
317 return MAX2(estimated, capacity());
318 }
319
320 bool ParallelScavengeHeap::is_in(const void* p) const {
321 if (young_gen()->is_in(p)) {
322 return true;
323 }
324
325 if (old_gen()->is_in(p)) {
326 return true;
327 }
328
329 if (perm_gen()->is_in(p)) {
330 return true;
331 }
332
333 return false;
334 }
335
336 bool ParallelScavengeHeap::is_in_reserved(const void* p) const {
337 if (young_gen()->is_in_reserved(p)) {
338 return true;
339 }
340
341 if (old_gen()->is_in_reserved(p)) {
342 return true;
343 }
344
345 if (perm_gen()->is_in_reserved(p)) {
346 return true;
347 }
348
349 return false;
350 }
351
352 bool ParallelScavengeHeap::is_scavengable(const void* addr) {
353 return is_in_young((oop)addr);
354 }
355
356 #ifdef ASSERT
357 // Don't implement this by using is_in_young(). This method is used
358 // in some cases to check that is_in_young() is correct.
359 bool ParallelScavengeHeap::is_in_partial_collection(const void *p) {
360 assert(is_in_reserved(p) || p == NULL,
361 "Does not work if address is non-null and outside of the heap");
362 // The order of the generations is perm (low addr), old, young (high addr)
363 return p >= old_gen()->reserved().end();
364 }
365 #endif
366
367 // There are two levels of allocation policy here.
368 //
369 // When an allocation request fails, the requesting thread must invoke a VM
370 // operation, transfer control to the VM thread, and await the results of a
371 // garbage collection. That is quite expensive, and we should avoid doing it
372 // multiple times if possible.
373 //
374 // To accomplish this, we have a basic allocation policy, and also a
375 // failed allocation policy.
376 //
377 // The basic allocation policy controls how you allocate memory without
378 // attempting garbage collection. It is okay to grab locks and
379 // expand the heap, if that can be done without coming to a safepoint.
380 // It is likely that the basic allocation policy will not be very
381 // aggressive.
382 //
383 // The failed allocation policy is invoked from the VM thread after
384 // the basic allocation policy is unable to satisfy a mem_allocate
385 // request. This policy needs to cover the entire range of collection,
386 // heap expansion, and out-of-memory conditions. It should make every
387 // attempt to allocate the requested memory.
388
389 // Basic allocation policy. Should never be called at a safepoint, or
390 // from the VM thread.
391 //
392 // This method must handle cases where many mem_allocate requests fail
393 // simultaneously. When that happens, only one VM operation will succeed,
394 // and the rest will not be executed. For that reason, this method loops
395 // during failed allocation attempts. If the java heap becomes exhausted,
396 // we rely on the size_policy object to force a bail out.
397 HeapWord* ParallelScavengeHeap::mem_allocate(
398 size_t size,
399 bool* gc_overhead_limit_was_exceeded) {
400 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
401 assert(Thread::current() != (Thread*)VMThread::vm_thread(), "should not be in vm thread");
402 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
403
404 // In general gc_overhead_limit_was_exceeded should be false so
405 // set it so here and reset it to true only if the gc time
406 // limit is being exceeded as checked below.
407 *gc_overhead_limit_was_exceeded = false;
408
409 HeapWord* result = young_gen()->allocate(size);
410
411 uint loop_count = 0;
412 uint gc_count = 0;
413
414 while (result == NULL) {
415 // We don't want to have multiple collections for a single filled generation.
416 // To prevent this, each thread tracks the total_collections() value, and if
417 // the count has changed, does not do a new collection.
418 //
419 // The collection count must be read only while holding the heap lock. VM
420 // operations also hold the heap lock during collections. There is a lock
421 // contention case where thread A blocks waiting on the Heap_lock, while
422 // thread B is holding it doing a collection. When thread A gets the lock,
423 // the collection count has already changed. To prevent duplicate collections,
424 // The policy MUST attempt allocations during the same period it reads the
425 // total_collections() value!
426 {
427 MutexLocker ml(Heap_lock);
428 gc_count = Universe::heap()->total_collections();
429
430 result = young_gen()->allocate(size);
431 if (result != NULL) {
432 return result;
433 }
434
435 // If certain conditions hold, try allocating from the old gen.
436 result = mem_allocate_old_gen(size);
437 if (result != NULL) {
438 return result;
439 }
440
441 // Failed to allocate without a gc.
442 if (GC_locker::is_active_and_needs_gc()) {
443 // If this thread is not in a jni critical section, we stall
444 // the requestor until the critical section has cleared and
445 // GC allowed. When the critical section clears, a GC is
446 // initiated by the last thread exiting the critical section; so
447 // we retry the allocation sequence from the beginning of the loop,
448 // rather than causing more, now probably unnecessary, GC attempts.
449 JavaThread* jthr = JavaThread::current();
450 if (!jthr->in_critical()) {
451 MutexUnlocker mul(Heap_lock);
452 GC_locker::stall_until_clear();
453 continue;
454 } else {
455 if (CheckJNICalls) {
456 fatal("Possible deadlock due to allocating while"
457 " in jni critical section");
458 }
459 return NULL;
460 }
461 }
462 }
463
464 if (result == NULL) {
465 // Generate a VM operation
466 VM_ParallelGCFailedAllocation op(size, gc_count);
467 VMThread::execute(&op);
468
469 // Did the VM operation execute? If so, return the result directly.
470 // This prevents us from looping until time out on requests that can
471 // not be satisfied.
472 if (op.prologue_succeeded()) {
473 assert(Universe::heap()->is_in_or_null(op.result()),
474 "result not in heap");
475
476 // If GC was locked out during VM operation then retry allocation
477 // and/or stall as necessary.
478 if (op.gc_locked()) {
479 assert(op.result() == NULL, "must be NULL if gc_locked() is true");
480 continue; // retry and/or stall as necessary
481 }
482
483 // Exit the loop if the gc time limit has been exceeded.
484 // The allocation must have failed above ("result" guarding
485 // this path is NULL) and the most recent collection has exceeded the
486 // gc overhead limit (although enough may have been collected to
487 // satisfy the allocation). Exit the loop so that an out-of-memory
488 // will be thrown (return a NULL ignoring the contents of
489 // op.result()),
490 // but clear gc_overhead_limit_exceeded so that the next collection
491 // starts with a clean slate (i.e., forgets about previous overhead
492 // excesses). Fill op.result() with a filler object so that the
493 // heap remains parsable.
494 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
495 const bool softrefs_clear = collector_policy()->all_soft_refs_clear();
496 assert(!limit_exceeded || softrefs_clear, "Should have been cleared");
497 if (limit_exceeded && softrefs_clear) {
498 *gc_overhead_limit_was_exceeded = true;
499 size_policy()->set_gc_overhead_limit_exceeded(false);
500 if (PrintGCDetails && Verbose) {
501 gclog_or_tty->print_cr("ParallelScavengeHeap::mem_allocate: "
502 "return NULL because gc_overhead_limit_exceeded is set");
503 }
504 if (op.result() != NULL) {
505 CollectedHeap::fill_with_object(op.result(), size);
506 }
507 return NULL;
508 }
509
510 return op.result();
511 }
512 }
513
514 // The policy object will prevent us from looping forever. If the
515 // time spent in gc crosses a threshold, we will bail out.
516 loop_count++;
517 if ((result == NULL) && (QueuedAllocationWarningCount > 0) &&
518 (loop_count % QueuedAllocationWarningCount == 0)) {
519 warning("ParallelScavengeHeap::mem_allocate retries %d times \n\t"
520 " size=%d", loop_count, size);
521 }
522 }
523
524 return result;
525 }
526
527 // A "death march" is a series of ultra-slow allocations in which a full gc is
528 // done before each allocation, and after the full gc the allocation still
529 // cannot be satisfied from the young gen. This routine detects that condition;
530 // it should be called after a full gc has been done and the allocation
531 // attempted from the young gen. The parameter 'addr' should be the result of
532 // that young gen allocation attempt.
533 void
534 ParallelScavengeHeap::death_march_check(HeapWord* const addr, size_t size) {
535 if (addr != NULL) {
536 _death_march_count = 0; // death march has ended
537 } else if (_death_march_count == 0) {
538 if (should_alloc_in_eden(size)) {
539 _death_march_count = 1; // death march has started
540 }
541 }
542 }
543
544 HeapWord* ParallelScavengeHeap::mem_allocate_old_gen(size_t size) {
545 if (!should_alloc_in_eden(size) || GC_locker::is_active_and_needs_gc()) {
546 // Size is too big for eden, or gc is locked out.
547 return old_gen()->allocate(size);
548 }
549
550 // If a "death march" is in progress, allocate from the old gen a limited
551 // number of times before doing a GC.
552 if (_death_march_count > 0) {
553 if (_death_march_count < 64) {
554 ++_death_march_count;
555 return old_gen()->allocate(size);
556 } else {
557 _death_march_count = 0;
558 }
559 }
560 return NULL;
561 }
562
563 // Failed allocation policy. Must be called from the VM thread, and
564 // only at a safepoint! Note that this method has policy for allocation
565 // flow, and NOT collection policy. So we do not check for gc collection
566 // time over limit here, that is the responsibility of the heap specific
567 // collection methods. This method decides where to attempt allocations,
568 // and when to attempt collections, but no collection specific policy.
569 HeapWord* ParallelScavengeHeap::failed_mem_allocate(size_t size) {
570 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
571 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
572 assert(!Universe::heap()->is_gc_active(), "not reentrant");
573 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
574
575 // We assume that allocation in eden will fail unless we collect.
576
577 // First level allocation failure, scavenge and allocate in young gen.
578 GCCauseSetter gccs(this, GCCause::_allocation_failure);
579 const bool invoked_full_gc = PSScavenge::invoke();
580 HeapWord* result = young_gen()->allocate(size);
581
582 // Second level allocation failure.
583 // Mark sweep and allocate in young generation.
584 if (result == NULL && !invoked_full_gc) {
585 invoke_full_gc(false);
586 result = young_gen()->allocate(size);
587 }
588
589 death_march_check(result, size);
590
591 // Third level allocation failure.
592 // After mark sweep and young generation allocation failure,
593 // allocate in old generation.
594 if (result == NULL) {
595 result = old_gen()->allocate(size);
596 }
597
598 // Fourth level allocation failure. We're running out of memory.
599 // More complete mark sweep and allocate in young generation.
600 if (result == NULL) {
601 invoke_full_gc(true);
602 result = young_gen()->allocate(size);
603 }
604
605 // Fifth level allocation failure.
606 // After more complete mark sweep, allocate in old generation.
607 if (result == NULL) {
608 result = old_gen()->allocate(size);
609 }
610
611 return result;
612 }
613
614 //
615 // This is the policy loop for allocating in the permanent generation.
616 // If the initial allocation fails, we create a vm operation which will
617 // cause a collection.
618 HeapWord* ParallelScavengeHeap::permanent_mem_allocate(size_t size) {
619 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
620 assert(Thread::current() != (Thread*)VMThread::vm_thread(), "should not be in vm thread");
621 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
622
623 HeapWord* result;
624
625 uint loop_count = 0;
626 uint gc_count = 0;
627 uint full_gc_count = 0;
628
629 do {
630 // We don't want to have multiple collections for a single filled generation.
631 // To prevent this, each thread tracks the total_collections() value, and if
632 // the count has changed, does not do a new collection.
633 //
634 // The collection count must be read only while holding the heap lock. VM
635 // operations also hold the heap lock during collections. There is a lock
636 // contention case where thread A blocks waiting on the Heap_lock, while
637 // thread B is holding it doing a collection. When thread A gets the lock,
638 // the collection count has already changed. To prevent duplicate collections,
639 // The policy MUST attempt allocations during the same period it reads the
640 // total_collections() value!
641 {
642 MutexLocker ml(Heap_lock);
643 gc_count = Universe::heap()->total_collections();
644 full_gc_count = Universe::heap()->total_full_collections();
645
646 result = perm_gen()->allocate_permanent(size);
647
648 if (result != NULL) {
649 return result;
650 }
651
652 if (GC_locker::is_active_and_needs_gc()) {
653 // If this thread is not in a jni critical section, we stall
654 // the requestor until the critical section has cleared and
655 // GC allowed. When the critical section clears, a GC is
656 // initiated by the last thread exiting the critical section; so
657 // we retry the allocation sequence from the beginning of the loop,
658 // rather than causing more, now probably unnecessary, GC attempts.
659 JavaThread* jthr = JavaThread::current();
660 if (!jthr->in_critical()) {
661 MutexUnlocker mul(Heap_lock);
662 GC_locker::stall_until_clear();
663 continue;
664 } else {
665 if (CheckJNICalls) {
666 fatal("Possible deadlock due to allocating while"
667 " in jni critical section");
668 }
669 return NULL;
670 }
671 }
672 }
673
674 if (result == NULL) {
675
676 // Exit the loop if the gc time limit has been exceeded.
677 // The allocation must have failed above (result must be NULL),
678 // and the most recent collection must have exceeded the
679 // gc time limit. Exit the loop so that an out-of-memory
680 // will be thrown (returning a NULL will do that), but
681 // clear gc_overhead_limit_exceeded so that the next collection
682 // will succeeded if the applications decides to handle the
683 // out-of-memory and tries to go on.
684 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
685 if (limit_exceeded) {
686 size_policy()->set_gc_overhead_limit_exceeded(false);
687 if (PrintGCDetails && Verbose) {
688 gclog_or_tty->print_cr("ParallelScavengeHeap::permanent_mem_allocate:"
689 " return NULL because gc_overhead_limit_exceeded is set");
690 }
691 assert(result == NULL, "Allocation did not fail");
692 return NULL;
693 }
694
695 // Generate a VM operation
696 VM_ParallelGCFailedPermanentAllocation op(size, gc_count, full_gc_count);
697 VMThread::execute(&op);
698
699 // Did the VM operation execute? If so, return the result directly.
700 // This prevents us from looping until time out on requests that can
701 // not be satisfied.
702 if (op.prologue_succeeded()) {
703 assert(Universe::heap()->is_in_permanent_or_null(op.result()),
704 "result not in heap");
705 // If GC was locked out during VM operation then retry allocation
706 // and/or stall as necessary.
707 if (op.gc_locked()) {
708 assert(op.result() == NULL, "must be NULL if gc_locked() is true");
709 continue; // retry and/or stall as necessary
710 }
711 // If a NULL results is being returned, an out-of-memory
712 // will be thrown now. Clear the gc_overhead_limit_exceeded
713 // flag to avoid the following situation.
714 // gc_overhead_limit_exceeded is set during a collection
715 // the collection fails to return enough space and an OOM is thrown
716 // a subsequent GC prematurely throws an out-of-memory because
717 // the gc_overhead_limit_exceeded counts did not start
718 // again from 0.
719 if (op.result() == NULL) {
720 size_policy()->reset_gc_overhead_limit_count();
721 }
722 return op.result();
723 }
724 }
725
726 // The policy object will prevent us from looping forever. If the
727 // time spent in gc crosses a threshold, we will bail out.
728 loop_count++;
729 if ((QueuedAllocationWarningCount > 0) &&
730 (loop_count % QueuedAllocationWarningCount == 0)) {
731 warning("ParallelScavengeHeap::permanent_mem_allocate retries %d times \n\t"
732 " size=%d", loop_count, size);
733 }
734 } while (result == NULL);
735
736 return result;
737 }
738
739 //
740 // This is the policy code for permanent allocations which have failed
741 // and require a collection. Note that just as in failed_mem_allocate,
742 // we do not set collection policy, only where & when to allocate and
743 // collect.
744 HeapWord* ParallelScavengeHeap::failed_permanent_mem_allocate(size_t size) {
745 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
746 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
747 assert(!Universe::heap()->is_gc_active(), "not reentrant");
748 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
749 assert(size > perm_gen()->free_in_words(), "Allocation should fail");
750
751 // We assume (and assert!) that an allocation at this point will fail
752 // unless we collect.
753
754 // First level allocation failure. Mark-sweep and allocate in perm gen.
755 GCCauseSetter gccs(this, GCCause::_allocation_failure);
756 invoke_full_gc(false);
757 HeapWord* result = perm_gen()->allocate_permanent(size);
758
759 // Second level allocation failure. We're running out of memory.
760 if (result == NULL) {
761 invoke_full_gc(true);
762 result = perm_gen()->allocate_permanent(size);
763 }
764
765 return result;
766 }
767
768 void ParallelScavengeHeap::ensure_parsability(bool retire_tlabs) {
769 CollectedHeap::ensure_parsability(retire_tlabs);
770 young_gen()->eden_space()->ensure_parsability();
771 }
772
773 size_t ParallelScavengeHeap::unsafe_max_alloc() {
774 return young_gen()->eden_space()->free_in_bytes();
775 }
776
777 size_t ParallelScavengeHeap::tlab_capacity(Thread* thr) const {
778 return young_gen()->eden_space()->tlab_capacity(thr);
779 }
780
781 size_t ParallelScavengeHeap::unsafe_max_tlab_alloc(Thread* thr) const {
782 return young_gen()->eden_space()->unsafe_max_tlab_alloc(thr);
783 }
784
785 HeapWord* ParallelScavengeHeap::allocate_new_tlab(size_t size) {
786 return young_gen()->allocate(size);
787 }
788
789 void ParallelScavengeHeap::accumulate_statistics_all_tlabs() {
790 CollectedHeap::accumulate_statistics_all_tlabs();
791 }
792
793 void ParallelScavengeHeap::resize_all_tlabs() {
794 CollectedHeap::resize_all_tlabs();
795 }
796
797 bool ParallelScavengeHeap::can_elide_initializing_store_barrier(oop new_obj) {
798 // We don't need barriers for stores to objects in the
799 // young gen and, a fortiori, for initializing stores to
800 // objects therein.
801 return is_in_young(new_obj);
802 }
803
804 // This method is used by System.gc() and JVMTI.
805 void ParallelScavengeHeap::collect(GCCause::Cause cause) {
806 assert(!Heap_lock->owned_by_self(),
807 "this thread should not own the Heap_lock");
808
809 unsigned int gc_count = 0;
810 unsigned int full_gc_count = 0;
811 {
812 MutexLocker ml(Heap_lock);
813 // This value is guarded by the Heap_lock
814 gc_count = Universe::heap()->total_collections();
815 full_gc_count = Universe::heap()->total_full_collections();
816 }
817
818 VM_ParallelGCSystemGC op(gc_count, full_gc_count, cause);
819 VMThread::execute(&op);
820 }
821
822 // This interface assumes that it's being called by the
823 // vm thread. It collects the heap assuming that the
824 // heap lock is already held and that we are executing in
825 // the context of the vm thread.
826 void ParallelScavengeHeap::collect_as_vm_thread(GCCause::Cause cause) {
827 assert(Thread::current()->is_VM_thread(), "Precondition#1");
828 assert(Heap_lock->is_locked(), "Precondition#2");
829 GCCauseSetter gcs(this, cause);
830 switch (cause) {
831 case GCCause::_heap_inspection:
832 case GCCause::_heap_dump: {
833 HandleMark hm;
834 invoke_full_gc(false);
835 break;
836 }
837 default: // XXX FIX ME
838 ShouldNotReachHere();
839 }
840 }
841
842
843 void ParallelScavengeHeap::oop_iterate(OopClosure* cl) {
844 Unimplemented();
845 }
846
847 void ParallelScavengeHeap::object_iterate(ObjectClosure* cl) {
848 young_gen()->object_iterate(cl);
849 old_gen()->object_iterate(cl);
850 perm_gen()->object_iterate(cl);
851 }
852
853 void ParallelScavengeHeap::permanent_oop_iterate(OopClosure* cl) {
854 Unimplemented();
855 }
856
857 void ParallelScavengeHeap::permanent_object_iterate(ObjectClosure* cl) {
858 perm_gen()->object_iterate(cl);
859 }
860
861 HeapWord* ParallelScavengeHeap::block_start(const void* addr) const {
862 if (young_gen()->is_in_reserved(addr)) {
863 assert(young_gen()->is_in(addr),
864 "addr should be in allocated part of young gen");
865 // called from os::print_location by find or VMError
866 if (Debugging || VMError::fatal_error_in_progress()) return NULL;
867 Unimplemented();
868 } else if (old_gen()->is_in_reserved(addr)) {
869 assert(old_gen()->is_in(addr),
870 "addr should be in allocated part of old gen");
871 return old_gen()->start_array()->object_start((HeapWord*)addr);
872 } else if (perm_gen()->is_in_reserved(addr)) {
873 assert(perm_gen()->is_in(addr),
874 "addr should be in allocated part of perm gen");
875 return perm_gen()->start_array()->object_start((HeapWord*)addr);
876 }
877 return 0;
878 }
879
880 size_t ParallelScavengeHeap::block_size(const HeapWord* addr) const {
881 return oop(addr)->size();
882 }
883
884 bool ParallelScavengeHeap::block_is_obj(const HeapWord* addr) const {
885 return block_start(addr) == addr;
886 }
887
888 jlong ParallelScavengeHeap::millis_since_last_gc() {
889 return UseParallelOldGC ?
890 PSParallelCompact::millis_since_last_gc() :
891 PSMarkSweep::millis_since_last_gc();
892 }
893
894 void ParallelScavengeHeap::prepare_for_verify() {
895 ensure_parsability(false); // no need to retire TLABs for verification
896 }
897
898 PSHeapSummary ParallelScavengeHeap::create_ps_heap_summary() {
899 PSOldGen* old = old_gen();
900 HeapWord* old_committed_end = (HeapWord*)old->virtual_space()->committed_high_addr();
901 VirtualSpaceSummary old_summary(old->reserved().start(), old_committed_end, old->reserved().end());
902 SpaceSummary old_space(old->reserved().start(), old_committed_end, old->used_in_bytes());
903
904 PSYoungGen* young = young_gen();
905 VirtualSpaceSummary young_summary(young->reserved().start(),
906 (HeapWord*)young->virtual_space()->committed_high_addr(), young->reserved().end());
907
908 MutableSpace* eden = young_gen()->eden_space();
909 SpaceSummary eden_space(eden->bottom(), eden->end(), eden->used_in_bytes());
910
911 MutableSpace* from = young_gen()->from_space();
912 SpaceSummary from_space(from->bottom(), from->end(), from->used_in_bytes());
913
914 MutableSpace* to = young_gen()->to_space();
915 SpaceSummary to_space(to->bottom(), to->end(), to->used_in_bytes());
916
917 VirtualSpaceSummary heap_summary = create_heap_space_summary();
918 return PSHeapSummary(heap_summary, used(), old_summary, old_space, young_summary, eden_space, from_space, to_space);
919 }
920
921 VirtualSpaceSummary ParallelScavengeHeap::create_perm_gen_space_summary() {
922 PSVirtualSpace* space = perm_gen()->virtual_space();
923 return VirtualSpaceSummary(
924 (HeapWord*)space->low_boundary(),
925 (HeapWord*)space->high(),
926 (HeapWord*)space->high_boundary());
927 }
928
929 void ParallelScavengeHeap::print_on(outputStream* st) const {
930 young_gen()->print_on(st);
931 old_gen()->print_on(st);
932 perm_gen()->print_on(st);
933 }
934
935 void ParallelScavengeHeap::gc_threads_do(ThreadClosure* tc) const {
936 PSScavenge::gc_task_manager()->threads_do(tc);
937 }
938
939 void ParallelScavengeHeap::print_gc_threads_on(outputStream* st) const {
940 PSScavenge::gc_task_manager()->print_threads_on(st);
941 }
942
943 void ParallelScavengeHeap::print_tracing_info() const {
944 if (TraceGen0Time) {
945 double time = PSScavenge::accumulated_time()->seconds();
946 tty->print_cr("[Accumulated GC generation 0 time %3.7f secs]", time);
947 }
948 if (TraceGen1Time) {
949 double time = PSMarkSweep::accumulated_time()->seconds();
950 tty->print_cr("[Accumulated GC generation 1 time %3.7f secs]", time);
951 }
952 }
953
954
955 void ParallelScavengeHeap::verify(bool silent, VerifyOption option /* ignored */) {
956 // Why do we need the total_collections()-filter below?
957 if (total_collections() > 0) {
958 if (!silent) {
959 gclog_or_tty->print("permanent ");
960 }
961 perm_gen()->verify();
962
963 if (!silent) {
964 gclog_or_tty->print("tenured ");
965 }
966 old_gen()->verify();
967
968 if (!silent) {
969 gclog_or_tty->print("eden ");
970 }
971 young_gen()->verify();
972 }
973 }
974
975 void ParallelScavengeHeap::print_heap_change(size_t prev_used) {
976 if (PrintGCDetails && Verbose) {
977 gclog_or_tty->print(" " SIZE_FORMAT
978 "->" SIZE_FORMAT
979 "(" SIZE_FORMAT ")",
980 prev_used, used(), capacity());
981 } else {
982 gclog_or_tty->print(" " SIZE_FORMAT "K"
983 "->" SIZE_FORMAT "K"
984 "(" SIZE_FORMAT "K)",
985 prev_used / K, used() / K, capacity() / K);
986 }
987 }
988
989 void ParallelScavengeHeap::trace_heap(GCWhen::Type when, GCTracer* gc_tracer) {
990 const PSHeapSummary& heap_summary = create_ps_heap_summary();
991 const PermGenSummary& perm_gen_summary = create_perm_gen_summary();
992 gc_tracer->report_gc_heap_summary(when, heap_summary, perm_gen_summary);
993 }
994
995 ParallelScavengeHeap* ParallelScavengeHeap::heap() {
996 assert(_psh != NULL, "Uninitialized access to ParallelScavengeHeap::heap()");
997 assert(_psh->kind() == CollectedHeap::ParallelScavengeHeap, "not a parallel scavenge heap");
998 return _psh;
999 }
1000
1001 // Before delegating the resize to the young generation,
1002 // the reserved space for the young and old generations
1003 // may be changed to accomodate the desired resize.
1004 void ParallelScavengeHeap::resize_young_gen(size_t eden_size,
1005 size_t survivor_size) {
1006 if (UseAdaptiveGCBoundary) {
1007 if (size_policy()->bytes_absorbed_from_eden() != 0) {
1008 size_policy()->reset_bytes_absorbed_from_eden();
1009 return; // The generation changed size already.
1010 }
1011 gens()->adjust_boundary_for_young_gen_needs(eden_size, survivor_size);
1012 }
1013
1014 // Delegate the resize to the generation.
1015 _young_gen->resize(eden_size, survivor_size);
1016 }
1017
1018 // Before delegating the resize to the old generation,
1019 // the reserved space for the young and old generations
1020 // may be changed to accomodate the desired resize.
1021 void ParallelScavengeHeap::resize_old_gen(size_t desired_free_space) {
1022 if (UseAdaptiveGCBoundary) {
1023 if (size_policy()->bytes_absorbed_from_eden() != 0) {
1024 size_policy()->reset_bytes_absorbed_from_eden();
1025 return; // The generation changed size already.
1026 }
1027 gens()->adjust_boundary_for_old_gen_needs(desired_free_space);
1028 }
1029
1030 // Delegate the resize to the generation.
1031 _old_gen->resize(desired_free_space);
1032 }
1033
1034 ParallelScavengeHeap::ParStrongRootsScope::ParStrongRootsScope() {
1035 // nothing particular
1036 }
1037
1038 ParallelScavengeHeap::ParStrongRootsScope::~ParStrongRootsScope() {
1039 // nothing particular
1040 }
1041
1042 #ifndef PRODUCT
1043 void ParallelScavengeHeap::record_gen_tops_before_GC() {
1044 if (ZapUnusedHeapArea) {
1045 young_gen()->record_spaces_top();
1046 old_gen()->record_spaces_top();
1047 perm_gen()->record_spaces_top();
1048 }
1049 }
1050
1051 void ParallelScavengeHeap::gen_mangle_unused_area() {
1052 if (ZapUnusedHeapArea) {
1053 young_gen()->eden_space()->mangle_unused_area();
1054 young_gen()->to_space()->mangle_unused_area();
1055 young_gen()->from_space()->mangle_unused_area();
1056 old_gen()->object_space()->mangle_unused_area();
1057 perm_gen()->object_space()->mangle_unused_area();
1058 }
1059 }
1060 #endif