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