1 /*
2 * Copyright 2001-2010 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 */
24
25 # include "incls/_precompiled.incl"
26 # include "incls/_parallelScavengeHeap.cpp.incl"
27
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;
35
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 }
52
53 jint ParallelScavengeHeap::initialize() {
54 CollectedHeap::pre_initialize();
55
56 // Cannot be initialized until after the flags are parsed
57 // GenerationSizer flag_parser;
58 _collector_policy = new GenerationSizer();
59
60 size_t yg_min_size = _collector_policy->min_young_gen_size();
61 size_t yg_max_size = _collector_policy->max_young_gen_size();
62 size_t og_min_size = _collector_policy->min_old_gen_size();
63 size_t og_max_size = _collector_policy->max_old_gen_size();
64 // Why isn't there a min_perm_gen_size()?
65 size_t pg_min_size = _collector_policy->perm_gen_size();
66 size_t pg_max_size = _collector_policy->max_perm_gen_size();
67
68 trace_gen_sizes("ps heap raw",
69 pg_min_size, pg_max_size,
70 og_min_size, og_max_size,
71 yg_min_size, yg_max_size);
72
73 // The ReservedSpace ctor used below requires that the page size for the perm
74 // gen is <= the page size for the rest of the heap (young + old gens).
75 const size_t og_page_sz = os::page_size_for_region(yg_min_size + og_min_size,
76 yg_max_size + og_max_size,
77 8);
78 const size_t pg_page_sz = MIN2(os::page_size_for_region(pg_min_size,
79 pg_max_size, 16),
80 og_page_sz);
81
82 const size_t pg_align = set_alignment(_perm_gen_alignment, pg_page_sz);
83 const size_t og_align = set_alignment(_old_gen_alignment, og_page_sz);
84 const size_t yg_align = set_alignment(_young_gen_alignment, og_page_sz);
85
86 // Update sizes to reflect the selected page size(s).
87 //
88 // NEEDS_CLEANUP. The default TwoGenerationCollectorPolicy uses NewRatio; it
89 // should check UseAdaptiveSizePolicy. Changes from generationSizer could
90 // move to the common code.
91 yg_min_size = align_size_up(yg_min_size, yg_align);
92 yg_max_size = align_size_up(yg_max_size, yg_align);
93 size_t yg_cur_size =
94 align_size_up(_collector_policy->young_gen_size(), yg_align);
95 yg_cur_size = MAX2(yg_cur_size, yg_min_size);
96
97 og_min_size = align_size_up(og_min_size, og_align);
98 og_max_size = align_size_up(og_max_size, og_align);
99 size_t og_cur_size =
100 align_size_up(_collector_policy->old_gen_size(), og_align);
101 og_cur_size = MAX2(og_cur_size, og_min_size);
102
103 pg_min_size = align_size_up(pg_min_size, pg_align);
104 pg_max_size = align_size_up(pg_max_size, pg_align);
105 size_t pg_cur_size = pg_min_size;
106
107 trace_gen_sizes("ps heap rnd",
108 pg_min_size, pg_max_size,
109 og_min_size, og_max_size,
110 yg_min_size, yg_max_size);
111
112 const size_t total_reserved = pg_max_size + og_max_size + yg_max_size;
113 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
114
115 // The main part of the heap (old gen + young gen) can often use a larger page
116 // size than is needed or wanted for the perm gen. Use the "compound
117 // alignment" ReservedSpace ctor to avoid having to use the same page size for
118 // all gens.
119
120 ReservedHeapSpace heap_rs(pg_max_size, pg_align, og_max_size + yg_max_size,
121 og_align, addr);
122
123 if (UseCompressedOops) {
124 if (addr != NULL && !heap_rs.is_reserved()) {
125 // Failed to reserve at specified address - the requested memory
126 // region is taken already, for example, by 'java' launcher.
127 // Try again to reserver heap higher.
128 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
129 ReservedHeapSpace heap_rs0(pg_max_size, pg_align, og_max_size + yg_max_size,
130 og_align, addr);
131 if (addr != NULL && !heap_rs0.is_reserved()) {
132 // Failed to reserve at specified address again - give up.
133 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
134 assert(addr == NULL, "");
135 ReservedHeapSpace heap_rs1(pg_max_size, pg_align, og_max_size + yg_max_size,
136 og_align, addr);
137 heap_rs = heap_rs1;
138 } else {
139 heap_rs = heap_rs0;
140 }
141 }
142 }
143
144 os::trace_page_sizes("ps perm", pg_min_size, pg_max_size, pg_page_sz,
145 heap_rs.base(), pg_max_size);
146 os::trace_page_sizes("ps main", og_min_size + yg_min_size,
147 og_max_size + yg_max_size, og_page_sz,
148 heap_rs.base() + pg_max_size,
149 heap_rs.size() - pg_max_size);
150 if (!heap_rs.is_reserved()) {
151 vm_shutdown_during_initialization(
152 "Could not reserve enough space for object heap");
153 return JNI_ENOMEM;
154 }
155
156 _reserved = MemRegion((HeapWord*)heap_rs.base(),
157 (HeapWord*)(heap_rs.base() + heap_rs.size()));
158
159 CardTableExtension* const barrier_set = new CardTableExtension(_reserved, 3);
160 _barrier_set = barrier_set;
161 oopDesc::set_bs(_barrier_set);
162 if (_barrier_set == NULL) {
163 vm_shutdown_during_initialization(
164 "Could not reserve enough space for barrier set");
165 return JNI_ENOMEM;
166 }
167
168 // Initial young gen size is 4 Mb
169 //
170 // XXX - what about flag_parser.young_gen_size()?
171 const size_t init_young_size = align_size_up(4 * M, yg_align);
172 yg_cur_size = MAX2(MIN2(init_young_size, yg_max_size), yg_cur_size);
173
174 // Split the reserved space into perm gen and the main heap (everything else).
175 // The main heap uses a different alignment.
176 ReservedSpace perm_rs = heap_rs.first_part(pg_max_size);
177 ReservedSpace main_rs = heap_rs.last_part(pg_max_size, og_align);
178
179 // Make up the generations
180 // Calculate the maximum size that a generation can grow. This
181 // includes growth into the other generation. Note that the
182 // parameter _max_gen_size is kept as the maximum
183 // size of the generation as the boundaries currently stand.
184 // _max_gen_size is still used as that value.
185 double max_gc_pause_sec = ((double) MaxGCPauseMillis)/1000.0;
186 double max_gc_minor_pause_sec = ((double) MaxGCMinorPauseMillis)/1000.0;
187
188 _gens = new AdjoiningGenerations(main_rs,
189 og_cur_size,
190 og_min_size,
191 og_max_size,
192 yg_cur_size,
193 yg_min_size,
194 yg_max_size,
195 yg_align);
196
197 _old_gen = _gens->old_gen();
198 _young_gen = _gens->young_gen();
199
200 const size_t eden_capacity = _young_gen->eden_space()->capacity_in_bytes();
201 const size_t old_capacity = _old_gen->capacity_in_bytes();
202 const size_t initial_promo_size = MIN2(eden_capacity, old_capacity);
203 _size_policy =
204 new PSAdaptiveSizePolicy(eden_capacity,
205 initial_promo_size,
206 young_gen()->to_space()->capacity_in_bytes(),
207 intra_heap_alignment(),
208 max_gc_pause_sec,
209 max_gc_minor_pause_sec,
210 GCTimeRatio
211 );
212
213 _perm_gen = new PSPermGen(perm_rs,
214 pg_align,
215 pg_cur_size,
216 pg_cur_size,
217 pg_max_size,
218 "perm", 2);
219
220 assert(!UseAdaptiveGCBoundary ||
221 (old_gen()->virtual_space()->high_boundary() ==
222 young_gen()->virtual_space()->low_boundary()),
223 "Boundaries must meet");
224 // initialize the policy counters - 2 collectors, 3 generations
225 _gc_policy_counters =
226 new PSGCAdaptivePolicyCounters("ParScav:MSC", 2, 3, _size_policy);
227 _psh = this;
228
229 // Set up the GCTaskManager
230 _gc_task_manager = GCTaskManager::create(ParallelGCThreads);
231
232 if (UseParallelOldGC && !PSParallelCompact::initialize()) {
233 return JNI_ENOMEM;
234 }
235
236 return JNI_OK;
237 }
238
239 void ParallelScavengeHeap::post_initialize() {
240 // Need to init the tenuring threshold
241 PSScavenge::initialize();
242 if (UseParallelOldGC) {
243 PSParallelCompact::post_initialize();
244 } else {
245 PSMarkSweep::initialize();
246 }
247 PSPromotionManager::initialize();
248 }
249
250 void ParallelScavengeHeap::update_counters() {
251 young_gen()->update_counters();
252 old_gen()->update_counters();
253 perm_gen()->update_counters();
254 }
255
256 size_t ParallelScavengeHeap::capacity() const {
257 size_t value = young_gen()->capacity_in_bytes() + old_gen()->capacity_in_bytes();
258 return value;
259 }
260
261 size_t ParallelScavengeHeap::used() const {
262 size_t value = young_gen()->used_in_bytes() + old_gen()->used_in_bytes();
263 return value;
264 }
265
266 bool ParallelScavengeHeap::is_maximal_no_gc() const {
267 return old_gen()->is_maximal_no_gc() && young_gen()->is_maximal_no_gc();
268 }
269
270
271 size_t ParallelScavengeHeap::permanent_capacity() const {
272 return perm_gen()->capacity_in_bytes();
273 }
274
275 size_t ParallelScavengeHeap::permanent_used() const {
276 return perm_gen()->used_in_bytes();
277 }
278
279 size_t ParallelScavengeHeap::max_capacity() const {
280 size_t estimated = reserved_region().byte_size();
281 estimated -= perm_gen()->reserved().byte_size();
282 if (UseAdaptiveSizePolicy) {
283 estimated -= _size_policy->max_survivor_size(young_gen()->max_size());
284 } else {
285 estimated -= young_gen()->to_space()->capacity_in_bytes();
286 }
287 return MAX2(estimated, capacity());
288 }
289
290 bool ParallelScavengeHeap::is_in(const void* p) const {
291 if (young_gen()->is_in(p)) {
292 return true;
293 }
294
295 if (old_gen()->is_in(p)) {
296 return true;
297 }
298
299 if (perm_gen()->is_in(p)) {
300 return true;
301 }
302
303 return false;
304 }
305
306 bool ParallelScavengeHeap::is_in_reserved(const void* p) const {
307 if (young_gen()->is_in_reserved(p)) {
308 return true;
309 }
310
311 if (old_gen()->is_in_reserved(p)) {
312 return true;
313 }
314
315 if (perm_gen()->is_in_reserved(p)) {
316 return true;
317 }
318
319 return false;
320 }
321
322 // There are two levels of allocation policy here.
323 //
324 // When an allocation request fails, the requesting thread must invoke a VM
325 // operation, transfer control to the VM thread, and await the results of a
326 // garbage collection. That is quite expensive, and we should avoid doing it
327 // multiple times if possible.
328 //
329 // To accomplish this, we have a basic allocation policy, and also a
330 // failed allocation policy.
331 //
332 // The basic allocation policy controls how you allocate memory without
333 // attempting garbage collection. It is okay to grab locks and
334 // expand the heap, if that can be done without coming to a safepoint.
335 // It is likely that the basic allocation policy will not be very
336 // aggressive.
337 //
338 // The failed allocation policy is invoked from the VM thread after
339 // the basic allocation policy is unable to satisfy a mem_allocate
340 // request. This policy needs to cover the entire range of collection,
341 // heap expansion, and out-of-memory conditions. It should make every
342 // attempt to allocate the requested memory.
343
344 // Basic allocation policy. Should never be called at a safepoint, or
345 // from the VM thread.
346 //
347 // This method must handle cases where many mem_allocate requests fail
348 // simultaneously. When that happens, only one VM operation will succeed,
349 // and the rest will not be executed. For that reason, this method loops
350 // during failed allocation attempts. If the java heap becomes exhausted,
351 // we rely on the size_policy object to force a bail out.
352 HeapWord* ParallelScavengeHeap::mem_allocate(
353 size_t size,
354 bool is_noref,
355 bool is_tlab,
356 bool* gc_overhead_limit_was_exceeded) {
357 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
358 assert(Thread::current() != (Thread*)VMThread::vm_thread(), "should not be in vm thread");
359 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
360
361 // In general gc_overhead_limit_was_exceeded should be false so
362 // set it so here and reset it to true only if the gc time
363 // limit is being exceeded as checked below.
364 *gc_overhead_limit_was_exceeded = false;
365
366 HeapWord* result = young_gen()->allocate(size, is_tlab);
367
368 uint loop_count = 0;
369 uint gc_count = 0;
370
371 while (result == NULL) {
372 // We don't want to have multiple collections for a single filled generation.
373 // To prevent this, each thread tracks the total_collections() value, and if
374 // the count has changed, does not do a new collection.
375 //
376 // The collection count must be read only while holding the heap lock. VM
377 // operations also hold the heap lock during collections. There is a lock
378 // contention case where thread A blocks waiting on the Heap_lock, while
379 // thread B is holding it doing a collection. When thread A gets the lock,
380 // the collection count has already changed. To prevent duplicate collections,
381 // The policy MUST attempt allocations during the same period it reads the
382 // total_collections() value!
383 {
384 MutexLocker ml(Heap_lock);
385 gc_count = Universe::heap()->total_collections();
386
387 result = young_gen()->allocate(size, is_tlab);
388
389 // (1) If the requested object is too large to easily fit in the
390 // young_gen, or
391 // (2) If GC is locked out via GCLocker, young gen is full and
392 // the need for a GC already signalled to GCLocker (done
393 // at a safepoint),
394 // ... then, rather than force a safepoint and (a potentially futile)
395 // collection (attempt) for each allocation, try allocation directly
396 // in old_gen. For case (2) above, we may in the future allow
397 // TLAB allocation directly in the old gen.
398 if (result != NULL) {
399 return result;
400 }
401 if (!is_tlab &&
402 size >= (young_gen()->eden_space()->capacity_in_words(Thread::current()) / 2)) {
403 result = old_gen()->allocate(size, is_tlab);
404 if (result != NULL) {
405 return result;
406 }
407 }
408 if (GC_locker::is_active_and_needs_gc()) {
409 // GC is locked out. If this is a TLAB allocation,
410 // return NULL; the requestor will retry allocation
411 // of an idividual object at a time.
412 if (is_tlab) {
413 return NULL;
414 }
415
416 // If this thread is not in a jni critical section, we stall
417 // the requestor until the critical section has cleared and
418 // GC allowed. When the critical section clears, a GC is
419 // initiated by the last thread exiting the critical section; so
420 // we retry the allocation sequence from the beginning of the loop,
421 // rather than causing more, now probably unnecessary, GC attempts.
422 JavaThread* jthr = JavaThread::current();
423 if (!jthr->in_critical()) {
424 MutexUnlocker mul(Heap_lock);
425 GC_locker::stall_until_clear();
426 continue;
427 } else {
428 if (CheckJNICalls) {
429 fatal("Possible deadlock due to allocating while"
430 " in jni critical section");
431 }
432 return NULL;
433 }
434 }
435 }
436
437 if (result == NULL) {
438
439 // Generate a VM operation
440 VM_ParallelGCFailedAllocation op(size, is_tlab, gc_count);
441 VMThread::execute(&op);
442
443 // Did the VM operation execute? If so, return the result directly.
444 // This prevents us from looping until time out on requests that can
445 // not be satisfied.
446 if (op.prologue_succeeded()) {
447 assert(Universe::heap()->is_in_or_null(op.result()),
448 "result not in heap");
449
450 // If GC was locked out during VM operation then retry allocation
451 // and/or stall as necessary.
452 if (op.gc_locked()) {
453 assert(op.result() == NULL, "must be NULL if gc_locked() is true");
454 continue; // retry and/or stall as necessary
455 }
456
457 // Exit the loop if the gc time limit has been exceeded.
458 // The allocation must have failed above ("result" guarding
459 // this path is NULL) and the most recent collection has exceeded the
460 // gc overhead limit (although enough may have been collected to
461 // satisfy the allocation). Exit the loop so that an out-of-memory
462 // will be thrown (return a NULL ignoring the contents of
463 // op.result()),
464 // but clear gc_overhead_limit_exceeded so that the next collection
465 // starts with a clean slate (i.e., forgets about previous overhead
466 // excesses). Fill op.result() with a filler object so that the
467 // heap remains parsable.
468 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
469 const bool softrefs_clear = collector_policy()->all_soft_refs_clear();
470 assert(!limit_exceeded || softrefs_clear, "Should have been cleared");
471 if (limit_exceeded && softrefs_clear) {
472 *gc_overhead_limit_was_exceeded = true;
473 size_policy()->set_gc_overhead_limit_exceeded(false);
474 if (PrintGCDetails && Verbose) {
475 gclog_or_tty->print_cr("ParallelScavengeHeap::mem_allocate: "
476 "return NULL because gc_overhead_limit_exceeded is set");
477 }
478 if (op.result() != NULL) {
479 CollectedHeap::fill_with_object(op.result(), size);
480 }
481 return NULL;
482 }
483
484 return op.result();
485 }
486 }
487
488 // The policy object will prevent us from looping forever. If the
489 // time spent in gc crosses a threshold, we will bail out.
490 loop_count++;
491 if ((result == NULL) && (QueuedAllocationWarningCount > 0) &&
492 (loop_count % QueuedAllocationWarningCount == 0)) {
493 warning("ParallelScavengeHeap::mem_allocate retries %d times \n\t"
494 " size=%d %s", loop_count, size, is_tlab ? "(TLAB)" : "");
495 }
496 }
497
498 return result;
499 }
500
501 // Failed allocation policy. Must be called from the VM thread, and
502 // only at a safepoint! Note that this method has policy for allocation
503 // flow, and NOT collection policy. So we do not check for gc collection
504 // time over limit here, that is the responsibility of the heap specific
505 // collection methods. This method decides where to attempt allocations,
506 // and when to attempt collections, but no collection specific policy.
507 HeapWord* ParallelScavengeHeap::failed_mem_allocate(size_t size, bool is_tlab) {
508 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
509 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
510 assert(!Universe::heap()->is_gc_active(), "not reentrant");
511 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
512
513 size_t mark_sweep_invocation_count = total_invocations();
514
515 // We assume (and assert!) that an allocation at this point will fail
516 // unless we collect.
517
518 // First level allocation failure, scavenge and allocate in young gen.
519 GCCauseSetter gccs(this, GCCause::_allocation_failure);
520 PSScavenge::invoke();
521 HeapWord* result = young_gen()->allocate(size, is_tlab);
522
523 // Second level allocation failure.
524 // Mark sweep and allocate in young generation.
525 if (result == NULL) {
526 // There is some chance the scavenge method decided to invoke mark_sweep.
527 // Don't mark sweep twice if so.
528 if (mark_sweep_invocation_count == total_invocations()) {
529 invoke_full_gc(false);
530 result = young_gen()->allocate(size, is_tlab);
531 }
532 }
533
534 // Third level allocation failure.
535 // After mark sweep and young generation allocation failure,
536 // allocate in old generation.
537 if (result == NULL && !is_tlab) {
538 result = old_gen()->allocate(size, is_tlab);
539 }
540
541 // Fourth level allocation failure. We're running out of memory.
542 // More complete mark sweep and allocate in young generation.
543 if (result == NULL) {
544 invoke_full_gc(true);
545 result = young_gen()->allocate(size, is_tlab);
546 }
547
548 // Fifth level allocation failure.
549 // After more complete mark sweep, allocate in old generation.
550 if (result == NULL && !is_tlab) {
551 result = old_gen()->allocate(size, is_tlab);
552 }
553
554 return result;
555 }
556
557 //
558 // This is the policy loop for allocating in the permanent generation.
559 // If the initial allocation fails, we create a vm operation which will
560 // cause a collection.
561 HeapWord* ParallelScavengeHeap::permanent_mem_allocate(size_t size) {
562 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
563 assert(Thread::current() != (Thread*)VMThread::vm_thread(), "should not be in vm thread");
564 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
565
566 HeapWord* result;
567
568 uint loop_count = 0;
569 uint gc_count = 0;
570 uint full_gc_count = 0;
571
572 do {
573 // We don't want to have multiple collections for a single filled generation.
574 // To prevent this, each thread tracks the total_collections() value, and if
575 // the count has changed, does not do a new collection.
576 //
577 // The collection count must be read only while holding the heap lock. VM
578 // operations also hold the heap lock during collections. There is a lock
579 // contention case where thread A blocks waiting on the Heap_lock, while
580 // thread B is holding it doing a collection. When thread A gets the lock,
581 // the collection count has already changed. To prevent duplicate collections,
582 // The policy MUST attempt allocations during the same period it reads the
583 // total_collections() value!
584 {
585 MutexLocker ml(Heap_lock);
586 gc_count = Universe::heap()->total_collections();
587 full_gc_count = Universe::heap()->total_full_collections();
588
589 result = perm_gen()->allocate_permanent(size);
590
591 if (result != NULL) {
592 return result;
593 }
594
595 if (GC_locker::is_active_and_needs_gc()) {
596 // If this thread is not in a jni critical section, we stall
597 // the requestor until the critical section has cleared and
598 // GC allowed. When the critical section clears, a GC is
599 // initiated by the last thread exiting the critical section; so
600 // we retry the allocation sequence from the beginning of the loop,
601 // rather than causing more, now probably unnecessary, GC attempts.
602 JavaThread* jthr = JavaThread::current();
603 if (!jthr->in_critical()) {
604 MutexUnlocker mul(Heap_lock);
605 GC_locker::stall_until_clear();
606 continue;
607 } else {
608 if (CheckJNICalls) {
609 fatal("Possible deadlock due to allocating while"
610 " in jni critical section");
611 }
612 return NULL;
613 }
614 }
615 }
616
617 if (result == NULL) {
618
619 // Exit the loop if the gc time limit has been exceeded.
620 // The allocation must have failed above (result must be NULL),
621 // and the most recent collection must have exceeded the
622 // gc time limit. Exit the loop so that an out-of-memory
623 // will be thrown (returning a NULL will do that), but
624 // clear gc_overhead_limit_exceeded so that the next collection
625 // will succeeded if the applications decides to handle the
626 // out-of-memory and tries to go on.
627 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
628 if (limit_exceeded) {
629 size_policy()->set_gc_overhead_limit_exceeded(false);
630 if (PrintGCDetails && Verbose) {
631 gclog_or_tty->print_cr("ParallelScavengeHeap::permanent_mem_allocate:"
632 " return NULL because gc_overhead_limit_exceeded is set");
633 }
634 assert(result == NULL, "Allocation did not fail");
635 return NULL;
636 }
637
638 // Generate a VM operation
639 VM_ParallelGCFailedPermanentAllocation op(size, gc_count, full_gc_count);
640 VMThread::execute(&op);
641
642 // Did the VM operation execute? If so, return the result directly.
643 // This prevents us from looping until time out on requests that can
644 // not be satisfied.
645 if (op.prologue_succeeded()) {
646 assert(Universe::heap()->is_in_permanent_or_null(op.result()),
647 "result not in heap");
648 // If GC was locked out during VM operation then retry allocation
649 // and/or stall as necessary.
650 if (op.gc_locked()) {
651 assert(op.result() == NULL, "must be NULL if gc_locked() is true");
652 continue; // retry and/or stall as necessary
653 }
654 // If a NULL results is being returned, an out-of-memory
655 // will be thrown now. Clear the gc_overhead_limit_exceeded
656 // flag to avoid the following situation.
657 // gc_overhead_limit_exceeded is set during a collection
658 // the collection fails to return enough space and an OOM is thrown
659 // a subsequent GC prematurely throws an out-of-memory because
660 // the gc_overhead_limit_exceeded counts did not start
661 // again from 0.
662 if (op.result() == NULL) {
663 size_policy()->reset_gc_overhead_limit_count();
664 }
665 return op.result();
666 }
667 }
668
669 // The policy object will prevent us from looping forever. If the
670 // time spent in gc crosses a threshold, we will bail out.
671 loop_count++;
672 if ((QueuedAllocationWarningCount > 0) &&
673 (loop_count % QueuedAllocationWarningCount == 0)) {
674 warning("ParallelScavengeHeap::permanent_mem_allocate retries %d times \n\t"
675 " size=%d", loop_count, size);
676 }
677 } while (result == NULL);
678
679 return result;
680 }
681
682 //
683 // This is the policy code for permanent allocations which have failed
684 // and require a collection. Note that just as in failed_mem_allocate,
685 // we do not set collection policy, only where & when to allocate and
686 // collect.
687 HeapWord* ParallelScavengeHeap::failed_permanent_mem_allocate(size_t size) {
688 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
689 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
690 assert(!Universe::heap()->is_gc_active(), "not reentrant");
691 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
692 assert(size > perm_gen()->free_in_words(), "Allocation should fail");
693
694 // We assume (and assert!) that an allocation at this point will fail
695 // unless we collect.
696
697 // First level allocation failure. Mark-sweep and allocate in perm gen.
698 GCCauseSetter gccs(this, GCCause::_allocation_failure);
699 invoke_full_gc(false);
700 HeapWord* result = perm_gen()->allocate_permanent(size);
701
702 // Second level allocation failure. We're running out of memory.
703 if (result == NULL) {
704 invoke_full_gc(true);
705 result = perm_gen()->allocate_permanent(size);
706 }
707
708 return result;
709 }
710
711 void ParallelScavengeHeap::ensure_parsability(bool retire_tlabs) {
712 CollectedHeap::ensure_parsability(retire_tlabs);
713 young_gen()->eden_space()->ensure_parsability();
714 }
715
716 size_t ParallelScavengeHeap::unsafe_max_alloc() {
717 return young_gen()->eden_space()->free_in_bytes();
718 }
719
720 size_t ParallelScavengeHeap::tlab_capacity(Thread* thr) const {
721 return young_gen()->eden_space()->tlab_capacity(thr);
722 }
723
724 size_t ParallelScavengeHeap::unsafe_max_tlab_alloc(Thread* thr) const {
725 return young_gen()->eden_space()->unsafe_max_tlab_alloc(thr);
726 }
727
728 HeapWord* ParallelScavengeHeap::allocate_new_tlab(size_t size) {
729 return young_gen()->allocate(size, true);
730 }
731
732 void ParallelScavengeHeap::accumulate_statistics_all_tlabs() {
733 CollectedHeap::accumulate_statistics_all_tlabs();
734 }
735
736 void ParallelScavengeHeap::resize_all_tlabs() {
737 CollectedHeap::resize_all_tlabs();
738 }
739
740 bool ParallelScavengeHeap::can_elide_initializing_store_barrier(oop new_obj) {
741 // We don't need barriers for stores to objects in the
742 // young gen and, a fortiori, for initializing stores to
743 // objects therein.
744 return is_in_young(new_obj);
745 }
746
747 // This method is used by System.gc() and JVMTI.
748 void ParallelScavengeHeap::collect(GCCause::Cause cause) {
749 assert(!Heap_lock->owned_by_self(),
750 "this thread should not own the Heap_lock");
751
752 unsigned int gc_count = 0;
753 unsigned int full_gc_count = 0;
754 {
755 MutexLocker ml(Heap_lock);
756 // This value is guarded by the Heap_lock
757 gc_count = Universe::heap()->total_collections();
758 full_gc_count = Universe::heap()->total_full_collections();
759 }
760
761 VM_ParallelGCSystemGC op(gc_count, full_gc_count, cause);
762 VMThread::execute(&op);
763 }
764
765 // This interface assumes that it's being called by the
766 // vm thread. It collects the heap assuming that the
767 // heap lock is already held and that we are executing in
768 // the context of the vm thread.
769 void ParallelScavengeHeap::collect_as_vm_thread(GCCause::Cause cause) {
770 assert(Thread::current()->is_VM_thread(), "Precondition#1");
771 assert(Heap_lock->is_locked(), "Precondition#2");
772 GCCauseSetter gcs(this, cause);
773 switch (cause) {
774 case GCCause::_heap_inspection:
775 case GCCause::_heap_dump: {
776 HandleMark hm;
777 invoke_full_gc(false);
778 break;
779 }
780 default: // XXX FIX ME
781 ShouldNotReachHere();
782 }
783 }
784
785
786 void ParallelScavengeHeap::oop_iterate(OopClosure* cl) {
787 Unimplemented();
788 }
789
790 void ParallelScavengeHeap::object_iterate(ObjectClosure* cl) {
791 young_gen()->object_iterate(cl);
792 old_gen()->object_iterate(cl);
793 perm_gen()->object_iterate(cl);
794 }
795
796 void ParallelScavengeHeap::permanent_oop_iterate(OopClosure* cl) {
797 Unimplemented();
798 }
799
800 void ParallelScavengeHeap::permanent_object_iterate(ObjectClosure* cl) {
801 perm_gen()->object_iterate(cl);
802 }
803
804 HeapWord* ParallelScavengeHeap::block_start(const void* addr) const {
805 if (young_gen()->is_in_reserved(addr)) {
806 assert(young_gen()->is_in(addr),
807 "addr should be in allocated part of young gen");
808 if (Debugging) return NULL; // called from find() in debug.cpp
809 Unimplemented();
810 } else if (old_gen()->is_in_reserved(addr)) {
811 assert(old_gen()->is_in(addr),
812 "addr should be in allocated part of old gen");
813 return old_gen()->start_array()->object_start((HeapWord*)addr);
814 } else if (perm_gen()->is_in_reserved(addr)) {
815 assert(perm_gen()->is_in(addr),
816 "addr should be in allocated part of perm gen");
817 return perm_gen()->start_array()->object_start((HeapWord*)addr);
818 }
819 return 0;
820 }
821
822 size_t ParallelScavengeHeap::block_size(const HeapWord* addr) const {
823 return oop(addr)->size();
824 }
825
826 bool ParallelScavengeHeap::block_is_obj(const HeapWord* addr) const {
827 return block_start(addr) == addr;
828 }
829
830 jlong ParallelScavengeHeap::millis_since_last_gc() {
831 return UseParallelOldGC ?
832 PSParallelCompact::millis_since_last_gc() :
833 PSMarkSweep::millis_since_last_gc();
834 }
835
836 void ParallelScavengeHeap::prepare_for_verify() {
837 ensure_parsability(false); // no need to retire TLABs for verification
838 }
839
840 void ParallelScavengeHeap::print() const { print_on(tty); }
841
842 void ParallelScavengeHeap::print_on(outputStream* st) const {
843 young_gen()->print_on(st);
844 old_gen()->print_on(st);
845 perm_gen()->print_on(st);
846 }
847
848 void ParallelScavengeHeap::gc_threads_do(ThreadClosure* tc) const {
849 PSScavenge::gc_task_manager()->threads_do(tc);
850 }
851
852 void ParallelScavengeHeap::print_gc_threads_on(outputStream* st) const {
853 PSScavenge::gc_task_manager()->print_threads_on(st);
854 }
855
856 void ParallelScavengeHeap::print_tracing_info() const {
857 if (TraceGen0Time) {
858 double time = PSScavenge::accumulated_time()->seconds();
859 tty->print_cr("[Accumulated GC generation 0 time %3.7f secs]", time);
860 }
861 if (TraceGen1Time) {
862 double time = PSMarkSweep::accumulated_time()->seconds();
863 tty->print_cr("[Accumulated GC generation 1 time %3.7f secs]", time);
864 }
865 }
866
867
868 void ParallelScavengeHeap::verify(bool allow_dirty, bool silent, bool option /* ignored */) {
869 // Why do we need the total_collections()-filter below?
870 if (total_collections() > 0) {
871 if (!silent) {
872 gclog_or_tty->print("permanent ");
873 }
874 perm_gen()->verify(allow_dirty);
875
876 if (!silent) {
877 gclog_or_tty->print("tenured ");
878 }
879 old_gen()->verify(allow_dirty);
880
881 if (!silent) {
882 gclog_or_tty->print("eden ");
883 }
884 young_gen()->verify(allow_dirty);
885 }
886 if (!silent) {
887 gclog_or_tty->print("ref_proc ");
888 }
889 ReferenceProcessor::verify();
890 }
891
892 void ParallelScavengeHeap::print_heap_change(size_t prev_used) {
893 if (PrintGCDetails && Verbose) {
894 gclog_or_tty->print(" " SIZE_FORMAT
895 "->" SIZE_FORMAT
896 "(" SIZE_FORMAT ")",
897 prev_used, used(), capacity());
898 } else {
899 gclog_or_tty->print(" " SIZE_FORMAT "K"
900 "->" SIZE_FORMAT "K"
901 "(" SIZE_FORMAT "K)",
902 prev_used / K, used() / K, capacity() / K);
903 }
904 }
905
906 ParallelScavengeHeap* ParallelScavengeHeap::heap() {
907 assert(_psh != NULL, "Uninitialized access to ParallelScavengeHeap::heap()");
908 assert(_psh->kind() == CollectedHeap::ParallelScavengeHeap, "not a parallel scavenge heap");
909 return _psh;
910 }
911
912 // Before delegating the resize to the young generation,
913 // the reserved space for the young and old generations
914 // may be changed to accomodate the desired resize.
915 void ParallelScavengeHeap::resize_young_gen(size_t eden_size,
916 size_t survivor_size) {
917 if (UseAdaptiveGCBoundary) {
918 if (size_policy()->bytes_absorbed_from_eden() != 0) {
919 size_policy()->reset_bytes_absorbed_from_eden();
920 return; // The generation changed size already.
921 }
922 gens()->adjust_boundary_for_young_gen_needs(eden_size, survivor_size);
923 }
924
925 // Delegate the resize to the generation.
926 _young_gen->resize(eden_size, survivor_size);
927 }
928
929 // Before delegating the resize to the old generation,
930 // the reserved space for the young and old generations
931 // may be changed to accomodate the desired resize.
932 void ParallelScavengeHeap::resize_old_gen(size_t desired_free_space) {
933 if (UseAdaptiveGCBoundary) {
934 if (size_policy()->bytes_absorbed_from_eden() != 0) {
935 size_policy()->reset_bytes_absorbed_from_eden();
936 return; // The generation changed size already.
937 }
938 gens()->adjust_boundary_for_old_gen_needs(desired_free_space);
939 }
940
941 // Delegate the resize to the generation.
942 _old_gen->resize(desired_free_space);
943 }
944
945 ParallelScavengeHeap::ParStrongRootsScope::ParStrongRootsScope() {
946 // nothing particular
947 }
948
949 ParallelScavengeHeap::ParStrongRootsScope::~ParStrongRootsScope() {
950 // nothing particular
951 }
952
953 #ifndef PRODUCT
954 void ParallelScavengeHeap::record_gen_tops_before_GC() {
955 if (ZapUnusedHeapArea) {
956 young_gen()->record_spaces_top();
957 old_gen()->record_spaces_top();
958 perm_gen()->record_spaces_top();
959 }
960 }
961
962 void ParallelScavengeHeap::gen_mangle_unused_area() {
963 if (ZapUnusedHeapArea) {
964 young_gen()->eden_space()->mangle_unused_area();
965 young_gen()->to_space()->mangle_unused_area();
966 young_gen()->from_space()->mangle_unused_area();
967 old_gen()->object_space()->mangle_unused_area();
968 perm_gen()->object_space()->mangle_unused_area();
969 }
970 }
971 #endif