Fri, 16 Oct 2009 02:05:46 -0700
6888898: CMS: ReduceInitialCardMarks unsafe in the presence of cms precleaning
6889757: G1: enable card mark elision for initializing writes from compiled code (ReduceInitialCardMarks)
Summary: Defer the (compiler-elided) card-mark upon a slow-path allocation until after the store and before the next subsequent safepoint; G1 now answers yes to can_elide_tlab_write_barriers().
Reviewed-by: jcoomes, kvn, never
1 /*
2 * Copyright 2001-2009 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 # include "incls/_precompiled.incl"
26 # include "incls/_parallelScavengeHeap.cpp.incl"
28 PSYoungGen* ParallelScavengeHeap::_young_gen = NULL;
29 PSOldGen* ParallelScavengeHeap::_old_gen = NULL;
30 PSPermGen* ParallelScavengeHeap::_perm_gen = NULL;
31 PSAdaptiveSizePolicy* ParallelScavengeHeap::_size_policy = NULL;
32 PSGCAdaptivePolicyCounters* ParallelScavengeHeap::_gc_policy_counters = NULL;
33 ParallelScavengeHeap* ParallelScavengeHeap::_psh = NULL;
34 GCTaskManager* ParallelScavengeHeap::_gc_task_manager = NULL;
36 static void trace_gen_sizes(const char* const str,
37 size_t pg_min, size_t pg_max,
38 size_t og_min, size_t og_max,
39 size_t yg_min, size_t yg_max)
40 {
41 if (TracePageSizes) {
42 tty->print_cr("%s: " SIZE_FORMAT "," SIZE_FORMAT " "
43 SIZE_FORMAT "," SIZE_FORMAT " "
44 SIZE_FORMAT "," SIZE_FORMAT " "
45 SIZE_FORMAT,
46 str, pg_min / K, pg_max / K,
47 og_min / K, og_max / K,
48 yg_min / K, yg_max / K,
49 (pg_max + og_max + yg_max) / K);
50 }
51 }
53 jint ParallelScavengeHeap::initialize() {
54 // Cannot be initialized until after the flags are parsed
55 GenerationSizer flag_parser;
57 size_t yg_min_size = flag_parser.min_young_gen_size();
58 size_t yg_max_size = flag_parser.max_young_gen_size();
59 size_t og_min_size = flag_parser.min_old_gen_size();
60 size_t og_max_size = flag_parser.max_old_gen_size();
61 // Why isn't there a min_perm_gen_size()?
62 size_t pg_min_size = flag_parser.perm_gen_size();
63 size_t pg_max_size = flag_parser.max_perm_gen_size();
65 trace_gen_sizes("ps heap raw",
66 pg_min_size, pg_max_size,
67 og_min_size, og_max_size,
68 yg_min_size, yg_max_size);
70 // The ReservedSpace ctor used below requires that the page size for the perm
71 // gen is <= the page size for the rest of the heap (young + old gens).
72 const size_t og_page_sz = os::page_size_for_region(yg_min_size + og_min_size,
73 yg_max_size + og_max_size,
74 8);
75 const size_t pg_page_sz = MIN2(os::page_size_for_region(pg_min_size,
76 pg_max_size, 16),
77 og_page_sz);
79 const size_t pg_align = set_alignment(_perm_gen_alignment, pg_page_sz);
80 const size_t og_align = set_alignment(_old_gen_alignment, og_page_sz);
81 const size_t yg_align = set_alignment(_young_gen_alignment, og_page_sz);
83 // Update sizes to reflect the selected page size(s).
84 //
85 // NEEDS_CLEANUP. The default TwoGenerationCollectorPolicy uses NewRatio; it
86 // should check UseAdaptiveSizePolicy. Changes from generationSizer could
87 // move to the common code.
88 yg_min_size = align_size_up(yg_min_size, yg_align);
89 yg_max_size = align_size_up(yg_max_size, yg_align);
90 size_t yg_cur_size = align_size_up(flag_parser.young_gen_size(), yg_align);
91 yg_cur_size = MAX2(yg_cur_size, yg_min_size);
93 og_min_size = align_size_up(og_min_size, og_align);
94 og_max_size = align_size_up(og_max_size, og_align);
95 size_t og_cur_size = align_size_up(flag_parser.old_gen_size(), og_align);
96 og_cur_size = MAX2(og_cur_size, og_min_size);
98 pg_min_size = align_size_up(pg_min_size, pg_align);
99 pg_max_size = align_size_up(pg_max_size, pg_align);
100 size_t pg_cur_size = pg_min_size;
102 trace_gen_sizes("ps heap rnd",
103 pg_min_size, pg_max_size,
104 og_min_size, og_max_size,
105 yg_min_size, yg_max_size);
107 const size_t total_reserved = pg_max_size + og_max_size + yg_max_size;
108 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
110 // The main part of the heap (old gen + young gen) can often use a larger page
111 // size than is needed or wanted for the perm gen. Use the "compound
112 // alignment" ReservedSpace ctor to avoid having to use the same page size for
113 // all gens.
115 ReservedHeapSpace heap_rs(pg_max_size, pg_align, og_max_size + yg_max_size,
116 og_align, addr);
118 if (UseCompressedOops) {
119 if (addr != NULL && !heap_rs.is_reserved()) {
120 // Failed to reserve at specified address - the requested memory
121 // region is taken already, for example, by 'java' launcher.
122 // Try again to reserver heap higher.
123 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
124 ReservedHeapSpace heap_rs0(pg_max_size, pg_align, og_max_size + yg_max_size,
125 og_align, addr);
126 if (addr != NULL && !heap_rs0.is_reserved()) {
127 // Failed to reserve at specified address again - give up.
128 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
129 assert(addr == NULL, "");
130 ReservedHeapSpace heap_rs1(pg_max_size, pg_align, og_max_size + yg_max_size,
131 og_align, addr);
132 heap_rs = heap_rs1;
133 } else {
134 heap_rs = heap_rs0;
135 }
136 }
137 }
139 os::trace_page_sizes("ps perm", pg_min_size, pg_max_size, pg_page_sz,
140 heap_rs.base(), pg_max_size);
141 os::trace_page_sizes("ps main", og_min_size + yg_min_size,
142 og_max_size + yg_max_size, og_page_sz,
143 heap_rs.base() + pg_max_size,
144 heap_rs.size() - pg_max_size);
145 if (!heap_rs.is_reserved()) {
146 vm_shutdown_during_initialization(
147 "Could not reserve enough space for object heap");
148 return JNI_ENOMEM;
149 }
151 _reserved = MemRegion((HeapWord*)heap_rs.base(),
152 (HeapWord*)(heap_rs.base() + heap_rs.size()));
154 CardTableExtension* const barrier_set = new CardTableExtension(_reserved, 3);
155 _barrier_set = barrier_set;
156 oopDesc::set_bs(_barrier_set);
157 if (_barrier_set == NULL) {
158 vm_shutdown_during_initialization(
159 "Could not reserve enough space for barrier set");
160 return JNI_ENOMEM;
161 }
163 // Initial young gen size is 4 Mb
164 //
165 // XXX - what about flag_parser.young_gen_size()?
166 const size_t init_young_size = align_size_up(4 * M, yg_align);
167 yg_cur_size = MAX2(MIN2(init_young_size, yg_max_size), yg_cur_size);
169 // Split the reserved space into perm gen and the main heap (everything else).
170 // The main heap uses a different alignment.
171 ReservedSpace perm_rs = heap_rs.first_part(pg_max_size);
172 ReservedSpace main_rs = heap_rs.last_part(pg_max_size, og_align);
174 // Make up the generations
175 // Calculate the maximum size that a generation can grow. This
176 // includes growth into the other generation. Note that the
177 // parameter _max_gen_size is kept as the maximum
178 // size of the generation as the boundaries currently stand.
179 // _max_gen_size is still used as that value.
180 double max_gc_pause_sec = ((double) MaxGCPauseMillis)/1000.0;
181 double max_gc_minor_pause_sec = ((double) MaxGCMinorPauseMillis)/1000.0;
183 _gens = new AdjoiningGenerations(main_rs,
184 og_cur_size,
185 og_min_size,
186 og_max_size,
187 yg_cur_size,
188 yg_min_size,
189 yg_max_size,
190 yg_align);
192 _old_gen = _gens->old_gen();
193 _young_gen = _gens->young_gen();
195 const size_t eden_capacity = _young_gen->eden_space()->capacity_in_bytes();
196 const size_t old_capacity = _old_gen->capacity_in_bytes();
197 const size_t initial_promo_size = MIN2(eden_capacity, old_capacity);
198 _size_policy =
199 new PSAdaptiveSizePolicy(eden_capacity,
200 initial_promo_size,
201 young_gen()->to_space()->capacity_in_bytes(),
202 intra_heap_alignment(),
203 max_gc_pause_sec,
204 max_gc_minor_pause_sec,
205 GCTimeRatio
206 );
208 _perm_gen = new PSPermGen(perm_rs,
209 pg_align,
210 pg_cur_size,
211 pg_cur_size,
212 pg_max_size,
213 "perm", 2);
215 assert(!UseAdaptiveGCBoundary ||
216 (old_gen()->virtual_space()->high_boundary() ==
217 young_gen()->virtual_space()->low_boundary()),
218 "Boundaries must meet");
219 // initialize the policy counters - 2 collectors, 3 generations
220 _gc_policy_counters =
221 new PSGCAdaptivePolicyCounters("ParScav:MSC", 2, 3, _size_policy);
222 _psh = this;
224 // Set up the GCTaskManager
225 _gc_task_manager = GCTaskManager::create(ParallelGCThreads);
227 if (UseParallelOldGC && !PSParallelCompact::initialize()) {
228 return JNI_ENOMEM;
229 }
231 return JNI_OK;
232 }
234 void ParallelScavengeHeap::post_initialize() {
235 // Need to init the tenuring threshold
236 PSScavenge::initialize();
237 if (UseParallelOldGC) {
238 PSParallelCompact::post_initialize();
239 } else {
240 PSMarkSweep::initialize();
241 }
242 PSPromotionManager::initialize();
243 }
245 void ParallelScavengeHeap::update_counters() {
246 young_gen()->update_counters();
247 old_gen()->update_counters();
248 perm_gen()->update_counters();
249 }
251 size_t ParallelScavengeHeap::capacity() const {
252 size_t value = young_gen()->capacity_in_bytes() + old_gen()->capacity_in_bytes();
253 return value;
254 }
256 size_t ParallelScavengeHeap::used() const {
257 size_t value = young_gen()->used_in_bytes() + old_gen()->used_in_bytes();
258 return value;
259 }
261 bool ParallelScavengeHeap::is_maximal_no_gc() const {
262 return old_gen()->is_maximal_no_gc() && young_gen()->is_maximal_no_gc();
263 }
266 size_t ParallelScavengeHeap::permanent_capacity() const {
267 return perm_gen()->capacity_in_bytes();
268 }
270 size_t ParallelScavengeHeap::permanent_used() const {
271 return perm_gen()->used_in_bytes();
272 }
274 size_t ParallelScavengeHeap::max_capacity() const {
275 size_t estimated = reserved_region().byte_size();
276 estimated -= perm_gen()->reserved().byte_size();
277 if (UseAdaptiveSizePolicy) {
278 estimated -= _size_policy->max_survivor_size(young_gen()->max_size());
279 } else {
280 estimated -= young_gen()->to_space()->capacity_in_bytes();
281 }
282 return MAX2(estimated, capacity());
283 }
285 bool ParallelScavengeHeap::is_in(const void* p) const {
286 if (young_gen()->is_in(p)) {
287 return true;
288 }
290 if (old_gen()->is_in(p)) {
291 return true;
292 }
294 if (perm_gen()->is_in(p)) {
295 return true;
296 }
298 return false;
299 }
301 bool ParallelScavengeHeap::is_in_reserved(const void* p) const {
302 if (young_gen()->is_in_reserved(p)) {
303 return true;
304 }
306 if (old_gen()->is_in_reserved(p)) {
307 return true;
308 }
310 if (perm_gen()->is_in_reserved(p)) {
311 return true;
312 }
314 return false;
315 }
317 // There are two levels of allocation policy here.
318 //
319 // When an allocation request fails, the requesting thread must invoke a VM
320 // operation, transfer control to the VM thread, and await the results of a
321 // garbage collection. That is quite expensive, and we should avoid doing it
322 // multiple times if possible.
323 //
324 // To accomplish this, we have a basic allocation policy, and also a
325 // failed allocation policy.
326 //
327 // The basic allocation policy controls how you allocate memory without
328 // attempting garbage collection. It is okay to grab locks and
329 // expand the heap, if that can be done without coming to a safepoint.
330 // It is likely that the basic allocation policy will not be very
331 // aggressive.
332 //
333 // The failed allocation policy is invoked from the VM thread after
334 // the basic allocation policy is unable to satisfy a mem_allocate
335 // request. This policy needs to cover the entire range of collection,
336 // heap expansion, and out-of-memory conditions. It should make every
337 // attempt to allocate the requested memory.
339 // Basic allocation policy. Should never be called at a safepoint, or
340 // from the VM thread.
341 //
342 // This method must handle cases where many mem_allocate requests fail
343 // simultaneously. When that happens, only one VM operation will succeed,
344 // and the rest will not be executed. For that reason, this method loops
345 // during failed allocation attempts. If the java heap becomes exhausted,
346 // we rely on the size_policy object to force a bail out.
347 HeapWord* ParallelScavengeHeap::mem_allocate(
348 size_t size,
349 bool is_noref,
350 bool is_tlab,
351 bool* gc_overhead_limit_was_exceeded) {
352 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
353 assert(Thread::current() != (Thread*)VMThread::vm_thread(), "should not be in vm thread");
354 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
356 HeapWord* result = young_gen()->allocate(size, is_tlab);
358 uint loop_count = 0;
359 uint gc_count = 0;
361 while (result == NULL) {
362 // We don't want to have multiple collections for a single filled generation.
363 // To prevent this, each thread tracks the total_collections() value, and if
364 // the count has changed, does not do a new collection.
365 //
366 // The collection count must be read only while holding the heap lock. VM
367 // operations also hold the heap lock during collections. There is a lock
368 // contention case where thread A blocks waiting on the Heap_lock, while
369 // thread B is holding it doing a collection. When thread A gets the lock,
370 // the collection count has already changed. To prevent duplicate collections,
371 // The policy MUST attempt allocations during the same period it reads the
372 // total_collections() value!
373 {
374 MutexLocker ml(Heap_lock);
375 gc_count = Universe::heap()->total_collections();
377 result = young_gen()->allocate(size, is_tlab);
379 // (1) If the requested object is too large to easily fit in the
380 // young_gen, or
381 // (2) If GC is locked out via GCLocker, young gen is full and
382 // the need for a GC already signalled to GCLocker (done
383 // at a safepoint),
384 // ... then, rather than force a safepoint and (a potentially futile)
385 // collection (attempt) for each allocation, try allocation directly
386 // in old_gen. For case (2) above, we may in the future allow
387 // TLAB allocation directly in the old gen.
388 if (result != NULL) {
389 return result;
390 }
391 if (!is_tlab &&
392 size >= (young_gen()->eden_space()->capacity_in_words(Thread::current()) / 2)) {
393 result = old_gen()->allocate(size, is_tlab);
394 if (result != NULL) {
395 return result;
396 }
397 }
398 if (GC_locker::is_active_and_needs_gc()) {
399 // GC is locked out. If this is a TLAB allocation,
400 // return NULL; the requestor will retry allocation
401 // of an idividual object at a time.
402 if (is_tlab) {
403 return NULL;
404 }
406 // If this thread is not in a jni critical section, we stall
407 // the requestor until the critical section has cleared and
408 // GC allowed. When the critical section clears, a GC is
409 // initiated by the last thread exiting the critical section; so
410 // we retry the allocation sequence from the beginning of the loop,
411 // rather than causing more, now probably unnecessary, GC attempts.
412 JavaThread* jthr = JavaThread::current();
413 if (!jthr->in_critical()) {
414 MutexUnlocker mul(Heap_lock);
415 GC_locker::stall_until_clear();
416 continue;
417 } else {
418 if (CheckJNICalls) {
419 fatal("Possible deadlock due to allocating while"
420 " in jni critical section");
421 }
422 return NULL;
423 }
424 }
425 }
427 if (result == NULL) {
429 // Exit the loop if if the gc time limit has been exceeded.
430 // The allocation must have failed above (result must be NULL),
431 // and the most recent collection must have exceeded the
432 // gc time limit. Exit the loop so that an out-of-memory
433 // will be thrown (returning a NULL will do that), but
434 // clear gc_time_limit_exceeded so that the next collection
435 // will succeeded if the applications decides to handle the
436 // out-of-memory and tries to go on.
437 *gc_overhead_limit_was_exceeded = size_policy()->gc_time_limit_exceeded();
438 if (size_policy()->gc_time_limit_exceeded()) {
439 size_policy()->set_gc_time_limit_exceeded(false);
440 if (PrintGCDetails && Verbose) {
441 gclog_or_tty->print_cr("ParallelScavengeHeap::mem_allocate: "
442 "return NULL because gc_time_limit_exceeded is set");
443 }
444 return NULL;
445 }
447 // Generate a VM operation
448 VM_ParallelGCFailedAllocation op(size, is_tlab, gc_count);
449 VMThread::execute(&op);
451 // Did the VM operation execute? If so, return the result directly.
452 // This prevents us from looping until time out on requests that can
453 // not be satisfied.
454 if (op.prologue_succeeded()) {
455 assert(Universe::heap()->is_in_or_null(op.result()),
456 "result not in heap");
458 // If GC was locked out during VM operation then retry allocation
459 // and/or stall as necessary.
460 if (op.gc_locked()) {
461 assert(op.result() == NULL, "must be NULL if gc_locked() is true");
462 continue; // retry and/or stall as necessary
463 }
464 // If a NULL result is being returned, an out-of-memory
465 // will be thrown now. Clear the gc_time_limit_exceeded
466 // flag to avoid the following situation.
467 // gc_time_limit_exceeded is set during a collection
468 // the collection fails to return enough space and an OOM is thrown
469 // the next GC is skipped because the gc_time_limit_exceeded
470 // flag is set and another OOM is thrown
471 if (op.result() == NULL) {
472 size_policy()->set_gc_time_limit_exceeded(false);
473 }
474 return op.result();
475 }
476 }
478 // The policy object will prevent us from looping forever. If the
479 // time spent in gc crosses a threshold, we will bail out.
480 loop_count++;
481 if ((result == NULL) && (QueuedAllocationWarningCount > 0) &&
482 (loop_count % QueuedAllocationWarningCount == 0)) {
483 warning("ParallelScavengeHeap::mem_allocate retries %d times \n\t"
484 " size=%d %s", loop_count, size, is_tlab ? "(TLAB)" : "");
485 }
486 }
488 return result;
489 }
491 // Failed allocation policy. Must be called from the VM thread, and
492 // only at a safepoint! Note that this method has policy for allocation
493 // flow, and NOT collection policy. So we do not check for gc collection
494 // time over limit here, that is the responsibility of the heap specific
495 // collection methods. This method decides where to attempt allocations,
496 // and when to attempt collections, but no collection specific policy.
497 HeapWord* ParallelScavengeHeap::failed_mem_allocate(size_t size, bool is_tlab) {
498 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
499 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
500 assert(!Universe::heap()->is_gc_active(), "not reentrant");
501 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
503 size_t mark_sweep_invocation_count = total_invocations();
505 // We assume (and assert!) that an allocation at this point will fail
506 // unless we collect.
508 // First level allocation failure, scavenge and allocate in young gen.
509 GCCauseSetter gccs(this, GCCause::_allocation_failure);
510 PSScavenge::invoke();
511 HeapWord* result = young_gen()->allocate(size, is_tlab);
513 // Second level allocation failure.
514 // Mark sweep and allocate in young generation.
515 if (result == NULL) {
516 // There is some chance the scavenge method decided to invoke mark_sweep.
517 // Don't mark sweep twice if so.
518 if (mark_sweep_invocation_count == total_invocations()) {
519 invoke_full_gc(false);
520 result = young_gen()->allocate(size, is_tlab);
521 }
522 }
524 // Third level allocation failure.
525 // After mark sweep and young generation allocation failure,
526 // allocate in old generation.
527 if (result == NULL && !is_tlab) {
528 result = old_gen()->allocate(size, is_tlab);
529 }
531 // Fourth level allocation failure. We're running out of memory.
532 // More complete mark sweep and allocate in young generation.
533 if (result == NULL) {
534 invoke_full_gc(true);
535 result = young_gen()->allocate(size, is_tlab);
536 }
538 // Fifth level allocation failure.
539 // After more complete mark sweep, allocate in old generation.
540 if (result == NULL && !is_tlab) {
541 result = old_gen()->allocate(size, is_tlab);
542 }
544 return result;
545 }
547 //
548 // This is the policy loop for allocating in the permanent generation.
549 // If the initial allocation fails, we create a vm operation which will
550 // cause a collection.
551 HeapWord* ParallelScavengeHeap::permanent_mem_allocate(size_t size) {
552 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
553 assert(Thread::current() != (Thread*)VMThread::vm_thread(), "should not be in vm thread");
554 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
556 HeapWord* result;
558 uint loop_count = 0;
559 uint gc_count = 0;
560 uint full_gc_count = 0;
562 do {
563 // We don't want to have multiple collections for a single filled generation.
564 // To prevent this, each thread tracks the total_collections() value, and if
565 // the count has changed, does not do a new collection.
566 //
567 // The collection count must be read only while holding the heap lock. VM
568 // operations also hold the heap lock during collections. There is a lock
569 // contention case where thread A blocks waiting on the Heap_lock, while
570 // thread B is holding it doing a collection. When thread A gets the lock,
571 // the collection count has already changed. To prevent duplicate collections,
572 // The policy MUST attempt allocations during the same period it reads the
573 // total_collections() value!
574 {
575 MutexLocker ml(Heap_lock);
576 gc_count = Universe::heap()->total_collections();
577 full_gc_count = Universe::heap()->total_full_collections();
579 result = perm_gen()->allocate_permanent(size);
581 if (result != NULL) {
582 return result;
583 }
585 if (GC_locker::is_active_and_needs_gc()) {
586 // If this thread is not in a jni critical section, we stall
587 // the requestor until the critical section has cleared and
588 // GC allowed. When the critical section clears, a GC is
589 // initiated by the last thread exiting the critical section; so
590 // we retry the allocation sequence from the beginning of the loop,
591 // rather than causing more, now probably unnecessary, GC attempts.
592 JavaThread* jthr = JavaThread::current();
593 if (!jthr->in_critical()) {
594 MutexUnlocker mul(Heap_lock);
595 GC_locker::stall_until_clear();
596 continue;
597 } else {
598 if (CheckJNICalls) {
599 fatal("Possible deadlock due to allocating while"
600 " in jni critical section");
601 }
602 return NULL;
603 }
604 }
605 }
607 if (result == NULL) {
609 // Exit the loop if the gc time limit has been exceeded.
610 // The allocation must have failed above (result must be NULL),
611 // and the most recent collection must have exceeded the
612 // gc time limit. Exit the loop so that an out-of-memory
613 // will be thrown (returning a NULL will do that), but
614 // clear gc_time_limit_exceeded so that the next collection
615 // will succeeded if the applications decides to handle the
616 // out-of-memory and tries to go on.
617 if (size_policy()->gc_time_limit_exceeded()) {
618 size_policy()->set_gc_time_limit_exceeded(false);
619 if (PrintGCDetails && Verbose) {
620 gclog_or_tty->print_cr("ParallelScavengeHeap::permanent_mem_allocate: "
621 "return NULL because gc_time_limit_exceeded is set");
622 }
623 assert(result == NULL, "Allocation did not fail");
624 return NULL;
625 }
627 // Generate a VM operation
628 VM_ParallelGCFailedPermanentAllocation op(size, gc_count, full_gc_count);
629 VMThread::execute(&op);
631 // Did the VM operation execute? If so, return the result directly.
632 // This prevents us from looping until time out on requests that can
633 // not be satisfied.
634 if (op.prologue_succeeded()) {
635 assert(Universe::heap()->is_in_permanent_or_null(op.result()),
636 "result not in heap");
637 // If GC was locked out during VM operation then retry allocation
638 // and/or stall as necessary.
639 if (op.gc_locked()) {
640 assert(op.result() == NULL, "must be NULL if gc_locked() is true");
641 continue; // retry and/or stall as necessary
642 }
643 // If a NULL results is being returned, an out-of-memory
644 // will be thrown now. Clear the gc_time_limit_exceeded
645 // flag to avoid the following situation.
646 // gc_time_limit_exceeded is set during a collection
647 // the collection fails to return enough space and an OOM is thrown
648 // the next GC is skipped because the gc_time_limit_exceeded
649 // flag is set and another OOM is thrown
650 if (op.result() == NULL) {
651 size_policy()->set_gc_time_limit_exceeded(false);
652 }
653 return op.result();
654 }
655 }
657 // The policy object will prevent us from looping forever. If the
658 // time spent in gc crosses a threshold, we will bail out.
659 loop_count++;
660 if ((QueuedAllocationWarningCount > 0) &&
661 (loop_count % QueuedAllocationWarningCount == 0)) {
662 warning("ParallelScavengeHeap::permanent_mem_allocate retries %d times \n\t"
663 " size=%d", loop_count, size);
664 }
665 } while (result == NULL);
667 return result;
668 }
670 //
671 // This is the policy code for permanent allocations which have failed
672 // and require a collection. Note that just as in failed_mem_allocate,
673 // we do not set collection policy, only where & when to allocate and
674 // collect.
675 HeapWord* ParallelScavengeHeap::failed_permanent_mem_allocate(size_t size) {
676 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
677 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
678 assert(!Universe::heap()->is_gc_active(), "not reentrant");
679 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
680 assert(size > perm_gen()->free_in_words(), "Allocation should fail");
682 // We assume (and assert!) that an allocation at this point will fail
683 // unless we collect.
685 // First level allocation failure. Mark-sweep and allocate in perm gen.
686 GCCauseSetter gccs(this, GCCause::_allocation_failure);
687 invoke_full_gc(false);
688 HeapWord* result = perm_gen()->allocate_permanent(size);
690 // Second level allocation failure. We're running out of memory.
691 if (result == NULL) {
692 invoke_full_gc(true);
693 result = perm_gen()->allocate_permanent(size);
694 }
696 return result;
697 }
699 void ParallelScavengeHeap::ensure_parsability(bool retire_tlabs) {
700 CollectedHeap::ensure_parsability(retire_tlabs);
701 young_gen()->eden_space()->ensure_parsability();
702 }
704 size_t ParallelScavengeHeap::unsafe_max_alloc() {
705 return young_gen()->eden_space()->free_in_bytes();
706 }
708 size_t ParallelScavengeHeap::tlab_capacity(Thread* thr) const {
709 return young_gen()->eden_space()->tlab_capacity(thr);
710 }
712 size_t ParallelScavengeHeap::unsafe_max_tlab_alloc(Thread* thr) const {
713 return young_gen()->eden_space()->unsafe_max_tlab_alloc(thr);
714 }
716 HeapWord* ParallelScavengeHeap::allocate_new_tlab(size_t size) {
717 return young_gen()->allocate(size, true);
718 }
720 void ParallelScavengeHeap::fill_all_tlabs(bool retire) {
721 CollectedHeap::fill_all_tlabs(retire);
722 }
724 void ParallelScavengeHeap::accumulate_statistics_all_tlabs() {
725 CollectedHeap::accumulate_statistics_all_tlabs();
726 }
728 void ParallelScavengeHeap::resize_all_tlabs() {
729 CollectedHeap::resize_all_tlabs();
730 }
732 bool ParallelScavengeHeap::can_elide_initializing_store_barrier(oop new_obj) {
733 // We don't need barriers for stores to objects in the
734 // young gen and, a fortiori, for initializing stores to
735 // objects therein.
736 return is_in_young(new_obj);
737 }
739 // This method is used by System.gc() and JVMTI.
740 void ParallelScavengeHeap::collect(GCCause::Cause cause) {
741 assert(!Heap_lock->owned_by_self(),
742 "this thread should not own the Heap_lock");
744 unsigned int gc_count = 0;
745 unsigned int full_gc_count = 0;
746 {
747 MutexLocker ml(Heap_lock);
748 // This value is guarded by the Heap_lock
749 gc_count = Universe::heap()->total_collections();
750 full_gc_count = Universe::heap()->total_full_collections();
751 }
753 VM_ParallelGCSystemGC op(gc_count, full_gc_count, cause);
754 VMThread::execute(&op);
755 }
757 // This interface assumes that it's being called by the
758 // vm thread. It collects the heap assuming that the
759 // heap lock is already held and that we are executing in
760 // the context of the vm thread.
761 void ParallelScavengeHeap::collect_as_vm_thread(GCCause::Cause cause) {
762 assert(Thread::current()->is_VM_thread(), "Precondition#1");
763 assert(Heap_lock->is_locked(), "Precondition#2");
764 GCCauseSetter gcs(this, cause);
765 switch (cause) {
766 case GCCause::_heap_inspection:
767 case GCCause::_heap_dump: {
768 HandleMark hm;
769 invoke_full_gc(false);
770 break;
771 }
772 default: // XXX FIX ME
773 ShouldNotReachHere();
774 }
775 }
778 void ParallelScavengeHeap::oop_iterate(OopClosure* cl) {
779 Unimplemented();
780 }
782 void ParallelScavengeHeap::object_iterate(ObjectClosure* cl) {
783 young_gen()->object_iterate(cl);
784 old_gen()->object_iterate(cl);
785 perm_gen()->object_iterate(cl);
786 }
788 void ParallelScavengeHeap::permanent_oop_iterate(OopClosure* cl) {
789 Unimplemented();
790 }
792 void ParallelScavengeHeap::permanent_object_iterate(ObjectClosure* cl) {
793 perm_gen()->object_iterate(cl);
794 }
796 HeapWord* ParallelScavengeHeap::block_start(const void* addr) const {
797 if (young_gen()->is_in_reserved(addr)) {
798 assert(young_gen()->is_in(addr),
799 "addr should be in allocated part of young gen");
800 if (Debugging) return NULL; // called from find() in debug.cpp
801 Unimplemented();
802 } else if (old_gen()->is_in_reserved(addr)) {
803 assert(old_gen()->is_in(addr),
804 "addr should be in allocated part of old gen");
805 return old_gen()->start_array()->object_start((HeapWord*)addr);
806 } else if (perm_gen()->is_in_reserved(addr)) {
807 assert(perm_gen()->is_in(addr),
808 "addr should be in allocated part of perm gen");
809 return perm_gen()->start_array()->object_start((HeapWord*)addr);
810 }
811 return 0;
812 }
814 size_t ParallelScavengeHeap::block_size(const HeapWord* addr) const {
815 return oop(addr)->size();
816 }
818 bool ParallelScavengeHeap::block_is_obj(const HeapWord* addr) const {
819 return block_start(addr) == addr;
820 }
822 jlong ParallelScavengeHeap::millis_since_last_gc() {
823 return UseParallelOldGC ?
824 PSParallelCompact::millis_since_last_gc() :
825 PSMarkSweep::millis_since_last_gc();
826 }
828 void ParallelScavengeHeap::prepare_for_verify() {
829 ensure_parsability(false); // no need to retire TLABs for verification
830 }
832 void ParallelScavengeHeap::print() const { print_on(tty); }
834 void ParallelScavengeHeap::print_on(outputStream* st) const {
835 young_gen()->print_on(st);
836 old_gen()->print_on(st);
837 perm_gen()->print_on(st);
838 }
840 void ParallelScavengeHeap::gc_threads_do(ThreadClosure* tc) const {
841 PSScavenge::gc_task_manager()->threads_do(tc);
842 }
844 void ParallelScavengeHeap::print_gc_threads_on(outputStream* st) const {
845 PSScavenge::gc_task_manager()->print_threads_on(st);
846 }
848 void ParallelScavengeHeap::print_tracing_info() const {
849 if (TraceGen0Time) {
850 double time = PSScavenge::accumulated_time()->seconds();
851 tty->print_cr("[Accumulated GC generation 0 time %3.7f secs]", time);
852 }
853 if (TraceGen1Time) {
854 double time = PSMarkSweep::accumulated_time()->seconds();
855 tty->print_cr("[Accumulated GC generation 1 time %3.7f secs]", time);
856 }
857 }
860 void ParallelScavengeHeap::verify(bool allow_dirty, bool silent, bool option /* ignored */) {
861 // Why do we need the total_collections()-filter below?
862 if (total_collections() > 0) {
863 if (!silent) {
864 gclog_or_tty->print("permanent ");
865 }
866 perm_gen()->verify(allow_dirty);
868 if (!silent) {
869 gclog_or_tty->print("tenured ");
870 }
871 old_gen()->verify(allow_dirty);
873 if (!silent) {
874 gclog_or_tty->print("eden ");
875 }
876 young_gen()->verify(allow_dirty);
877 }
878 if (!silent) {
879 gclog_or_tty->print("ref_proc ");
880 }
881 ReferenceProcessor::verify();
882 }
884 void ParallelScavengeHeap::print_heap_change(size_t prev_used) {
885 if (PrintGCDetails && Verbose) {
886 gclog_or_tty->print(" " SIZE_FORMAT
887 "->" SIZE_FORMAT
888 "(" SIZE_FORMAT ")",
889 prev_used, used(), capacity());
890 } else {
891 gclog_or_tty->print(" " SIZE_FORMAT "K"
892 "->" SIZE_FORMAT "K"
893 "(" SIZE_FORMAT "K)",
894 prev_used / K, used() / K, capacity() / K);
895 }
896 }
898 ParallelScavengeHeap* ParallelScavengeHeap::heap() {
899 assert(_psh != NULL, "Uninitialized access to ParallelScavengeHeap::heap()");
900 assert(_psh->kind() == CollectedHeap::ParallelScavengeHeap, "not a parallel scavenge heap");
901 return _psh;
902 }
904 // Before delegating the resize to the young generation,
905 // the reserved space for the young and old generations
906 // may be changed to accomodate the desired resize.
907 void ParallelScavengeHeap::resize_young_gen(size_t eden_size,
908 size_t survivor_size) {
909 if (UseAdaptiveGCBoundary) {
910 if (size_policy()->bytes_absorbed_from_eden() != 0) {
911 size_policy()->reset_bytes_absorbed_from_eden();
912 return; // The generation changed size already.
913 }
914 gens()->adjust_boundary_for_young_gen_needs(eden_size, survivor_size);
915 }
917 // Delegate the resize to the generation.
918 _young_gen->resize(eden_size, survivor_size);
919 }
921 // Before delegating the resize to the old generation,
922 // the reserved space for the young and old generations
923 // may be changed to accomodate the desired resize.
924 void ParallelScavengeHeap::resize_old_gen(size_t desired_free_space) {
925 if (UseAdaptiveGCBoundary) {
926 if (size_policy()->bytes_absorbed_from_eden() != 0) {
927 size_policy()->reset_bytes_absorbed_from_eden();
928 return; // The generation changed size already.
929 }
930 gens()->adjust_boundary_for_old_gen_needs(desired_free_space);
931 }
933 // Delegate the resize to the generation.
934 _old_gen->resize(desired_free_space);
935 }
937 ParallelScavengeHeap::ParStrongRootsScope::ParStrongRootsScope() {
938 // nothing particular
939 }
941 ParallelScavengeHeap::ParStrongRootsScope::~ParStrongRootsScope() {
942 // nothing particular
943 }
945 #ifndef PRODUCT
946 void ParallelScavengeHeap::record_gen_tops_before_GC() {
947 if (ZapUnusedHeapArea) {
948 young_gen()->record_spaces_top();
949 old_gen()->record_spaces_top();
950 perm_gen()->record_spaces_top();
951 }
952 }
954 void ParallelScavengeHeap::gen_mangle_unused_area() {
955 if (ZapUnusedHeapArea) {
956 young_gen()->eden_space()->mangle_unused_area();
957 young_gen()->to_space()->mangle_unused_area();
958 young_gen()->from_space()->mangle_unused_area();
959 old_gen()->object_space()->mangle_unused_area();
960 perm_gen()->object_space()->mangle_unused_area();
961 }
962 }
963 #endif