1 /*
2 * Copyright (c) 2001, 2013, 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/shared/adaptiveSizePolicy.hpp"
27 #include "gc_implementation/shared/gcPolicyCounters.hpp"
28 #include "gc_implementation/shared/vmGCOperations.hpp"
29 #include "memory/cardTableRS.hpp"
30 #include "memory/collectorPolicy.hpp"
31 #include "memory/gcLocker.inline.hpp"
32 #include "memory/genCollectedHeap.hpp"
33 #include "memory/generationSpec.hpp"
34 #include "memory/space.hpp"
35 #include "memory/universe.hpp"
36 #include "runtime/arguments.hpp"
37 #include "runtime/globals_extension.hpp"
38 #include "runtime/handles.inline.hpp"
39 #include "runtime/java.hpp"
40 #include "runtime/thread.inline.hpp"
41 #include "runtime/vmThread.hpp"
42 #include "utilities/macros.hpp"
43 #if INCLUDE_ALL_GCS
44 #include "gc_implementation/concurrentMarkSweep/cmsAdaptiveSizePolicy.hpp"
45 #include "gc_implementation/concurrentMarkSweep/cmsGCAdaptivePolicyCounters.hpp"
46 #endif // INCLUDE_ALL_GCS
47
48 // CollectorPolicy methods.
49
50 // Align down. If the aligning result in 0, return 'alignment'.
51 static size_t restricted_align_down(size_t size, size_t alignment) {
52 return MAX2(alignment, align_size_down_(size, alignment));
53 }
54
55 void CollectorPolicy::initialize_flags() {
56 assert(max_alignment() >= min_alignment(),
57 err_msg("max_alignment: " SIZE_FORMAT " less than min_alignment: " SIZE_FORMAT,
58 max_alignment(), min_alignment()));
59 assert(max_alignment() % min_alignment() == 0,
60 err_msg("max_alignment: " SIZE_FORMAT " not aligned by min_alignment: " SIZE_FORMAT,
61 max_alignment(), min_alignment()));
62
63 if (MaxHeapSize < InitialHeapSize) {
64 vm_exit_during_initialization("Incompatible initial and maximum heap sizes specified");
65 }
66
67 if (!is_size_aligned(MaxMetaspaceSize, max_alignment())) {
68 FLAG_SET_ERGO(uintx, MaxMetaspaceSize,
69 restricted_align_down(MaxMetaspaceSize, max_alignment()));
70 }
71
72 if (MetaspaceSize > MaxMetaspaceSize) {
73 FLAG_SET_ERGO(uintx, MetaspaceSize, MaxMetaspaceSize);
74 }
75
76 if (!is_size_aligned(MetaspaceSize, min_alignment())) {
77 FLAG_SET_ERGO(uintx, MetaspaceSize,
78 restricted_align_down(MetaspaceSize, min_alignment()));
79 }
80
81 assert(MetaspaceSize <= MaxMetaspaceSize, "Must be");
82
83 MinMetaspaceExpansion = restricted_align_down(MinMetaspaceExpansion, min_alignment());
84 MaxMetaspaceExpansion = restricted_align_down(MaxMetaspaceExpansion, min_alignment());
85
86 MinHeapDeltaBytes = align_size_up(MinHeapDeltaBytes, min_alignment());
87
88 assert(MetaspaceSize % min_alignment() == 0, "metapace alignment");
89 assert(MaxMetaspaceSize % max_alignment() == 0, "maximum metaspace alignment");
90 if (MetaspaceSize < 256*K) {
91 vm_exit_during_initialization("Too small initial Metaspace size");
92 }
93 }
94
95 void CollectorPolicy::initialize_size_info() {
96 // User inputs from -mx and ms must be aligned
97 set_min_heap_byte_size(align_size_up(Arguments::min_heap_size(), min_alignment()));
98 set_initial_heap_byte_size(align_size_up(InitialHeapSize, min_alignment()));
99 set_max_heap_byte_size(align_size_up(MaxHeapSize, max_alignment()));
100
101 // Check heap parameter properties
102 if (initial_heap_byte_size() < M) {
103 vm_exit_during_initialization("Too small initial heap");
104 }
105 // Check heap parameter properties
106 if (min_heap_byte_size() < M) {
107 vm_exit_during_initialization("Too small minimum heap");
108 }
109 if (initial_heap_byte_size() <= NewSize) {
110 // make sure there is at least some room in old space
111 vm_exit_during_initialization("Too small initial heap for new size specified");
112 }
113 if (max_heap_byte_size() < min_heap_byte_size()) {
114 vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified");
115 }
116 if (initial_heap_byte_size() < min_heap_byte_size()) {
117 vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified");
118 }
119 if (max_heap_byte_size() < initial_heap_byte_size()) {
120 vm_exit_during_initialization("Incompatible initial and maximum heap sizes specified");
121 }
122
123 if (PrintGCDetails && Verbose) {
124 gclog_or_tty->print_cr("Minimum heap " SIZE_FORMAT " Initial heap "
125 SIZE_FORMAT " Maximum heap " SIZE_FORMAT,
126 min_heap_byte_size(), initial_heap_byte_size(), max_heap_byte_size());
127 }
128 }
129
130 bool CollectorPolicy::use_should_clear_all_soft_refs(bool v) {
131 bool result = _should_clear_all_soft_refs;
132 set_should_clear_all_soft_refs(false);
133 return result;
134 }
135
136 GenRemSet* CollectorPolicy::create_rem_set(MemRegion whole_heap,
137 int max_covered_regions) {
138 switch (rem_set_name()) {
139 case GenRemSet::CardTable: {
140 CardTableRS* res = new CardTableRS(whole_heap, max_covered_regions);
141 return res;
142 }
143 default:
144 guarantee(false, "unrecognized GenRemSet::Name");
145 return NULL;
146 }
147 }
148
149 void CollectorPolicy::cleared_all_soft_refs() {
150 // If near gc overhear limit, continue to clear SoftRefs. SoftRefs may
151 // have been cleared in the last collection but if the gc overhear
152 // limit continues to be near, SoftRefs should still be cleared.
153 if (size_policy() != NULL) {
154 _should_clear_all_soft_refs = size_policy()->gc_overhead_limit_near();
155 }
156 _all_soft_refs_clear = true;
157 }
158
159 size_t CollectorPolicy::compute_max_alignment() {
160 // The card marking array and the offset arrays for old generations are
161 // committed in os pages as well. Make sure they are entirely full (to
162 // avoid partial page problems), e.g. if 512 bytes heap corresponds to 1
163 // byte entry and the os page size is 4096, the maximum heap size should
164 // be 512*4096 = 2MB aligned.
165
166 // There is only the GenRemSet in Hotspot and only the GenRemSet::CardTable
167 // is supported.
168 // Requirements of any new remembered set implementations must be added here.
169 size_t alignment = GenRemSet::max_alignment_constraint(GenRemSet::CardTable);
170
171 // Parallel GC does its own alignment of the generations to avoid requiring a
172 // large page (256M on some platforms) for the permanent generation. The
173 // other collectors should also be updated to do their own alignment and then
174 // this use of lcm() should be removed.
175 if (UseLargePages && !UseParallelGC) {
176 // in presence of large pages we have to make sure that our
177 // alignment is large page aware
178 alignment = lcm(os::large_page_size(), alignment);
179 }
180
181 return alignment;
182 }
183
184 // GenCollectorPolicy methods.
185
186 size_t GenCollectorPolicy::scale_by_NewRatio_aligned(size_t base_size) {
187 size_t x = base_size / (NewRatio+1);
188 size_t new_gen_size = x > min_alignment() ?
189 align_size_down(x, min_alignment()) :
190 min_alignment();
191 return new_gen_size;
192 }
193
194 size_t GenCollectorPolicy::bound_minus_alignment(size_t desired_size,
195 size_t maximum_size) {
196 size_t alignment = min_alignment();
197 size_t max_minus = maximum_size - alignment;
198 return desired_size < max_minus ? desired_size : max_minus;
199 }
200
201
202 void GenCollectorPolicy::initialize_size_policy(size_t init_eden_size,
203 size_t init_promo_size,
204 size_t init_survivor_size) {
205 const double max_gc_pause_sec = ((double) MaxGCPauseMillis)/1000.0;
206 _size_policy = new AdaptiveSizePolicy(init_eden_size,
207 init_promo_size,
208 init_survivor_size,
209 max_gc_pause_sec,
210 GCTimeRatio);
211 }
212
213 void GenCollectorPolicy::initialize_flags() {
214 // All sizes must be multiples of the generation granularity.
215 set_min_alignment((uintx) Generation::GenGrain);
216 set_max_alignment(compute_max_alignment());
217
218 CollectorPolicy::initialize_flags();
219
220 // All generational heaps have a youngest gen; handle those flags here.
221
222 // Adjust max size parameters
223 if (NewSize > MaxNewSize) {
224 MaxNewSize = NewSize;
225 }
226 NewSize = align_size_down(NewSize, min_alignment());
227 MaxNewSize = align_size_down(MaxNewSize, min_alignment());
228
229 // Check validity of heap flags
230 assert(NewSize % min_alignment() == 0, "eden space alignment");
231 assert(MaxNewSize % min_alignment() == 0, "survivor space alignment");
232
233 if (NewSize < 3*min_alignment()) {
234 // make sure there room for eden and two survivor spaces
235 vm_exit_during_initialization("Too small new size specified");
236 }
237 if (SurvivorRatio < 1 || NewRatio < 1) {
238 vm_exit_during_initialization("Invalid heap ratio specified");
239 }
240 }
241
242 void TwoGenerationCollectorPolicy::initialize_flags() {
243 GenCollectorPolicy::initialize_flags();
244
245 OldSize = align_size_down(OldSize, min_alignment());
246
247 if (FLAG_IS_CMDLINE(OldSize) && FLAG_IS_DEFAULT(NewSize)) {
248 // NewRatio will be used later to set the young generation size so we use
249 // it to calculate how big the heap should be based on the requested OldSize
250 // and NewRatio.
251 assert(NewRatio > 0, "NewRatio should have been set up earlier");
252 size_t calculated_heapsize = (OldSize / NewRatio) * (NewRatio + 1);
253
254 calculated_heapsize = align_size_up(calculated_heapsize, max_alignment());
255 MaxHeapSize = calculated_heapsize;
256 InitialHeapSize = calculated_heapsize;
257 }
258 MaxHeapSize = align_size_up(MaxHeapSize, max_alignment());
259
260 // adjust max heap size if necessary
261 if (NewSize + OldSize > MaxHeapSize) {
262 if (FLAG_IS_CMDLINE(MaxHeapSize)) {
263 // somebody set a maximum heap size with the intention that we should not
264 // exceed it. Adjust New/OldSize as necessary.
265 uintx calculated_size = NewSize + OldSize;
266 double shrink_factor = (double) MaxHeapSize / calculated_size;
267 // align
268 NewSize = align_size_down((uintx) (NewSize * shrink_factor), min_alignment());
269 // OldSize is already aligned because above we aligned MaxHeapSize to
270 // max_alignment(), and we just made sure that NewSize is aligned to
271 // min_alignment(). In initialize_flags() we verified that max_alignment()
272 // is a multiple of min_alignment().
273 OldSize = MaxHeapSize - NewSize;
274 } else {
275 MaxHeapSize = NewSize + OldSize;
276 }
277 }
278 // need to do this again
279 MaxHeapSize = align_size_up(MaxHeapSize, max_alignment());
280
281 // adjust max heap size if necessary
282 if (NewSize + OldSize > MaxHeapSize) {
283 if (FLAG_IS_CMDLINE(MaxHeapSize)) {
284 // somebody set a maximum heap size with the intention that we should not
285 // exceed it. Adjust New/OldSize as necessary.
286 uintx calculated_size = NewSize + OldSize;
287 double shrink_factor = (double) MaxHeapSize / calculated_size;
288 // align
289 NewSize = align_size_down((uintx) (NewSize * shrink_factor), min_alignment());
290 // OldSize is already aligned because above we aligned MaxHeapSize to
291 // max_alignment(), and we just made sure that NewSize is aligned to
292 // min_alignment(). In initialize_flags() we verified that max_alignment()
293 // is a multiple of min_alignment().
294 OldSize = MaxHeapSize - NewSize;
295 } else {
296 MaxHeapSize = NewSize + OldSize;
297 }
298 }
299 // need to do this again
300 MaxHeapSize = align_size_up(MaxHeapSize, max_alignment());
301
302 always_do_update_barrier = UseConcMarkSweepGC;
303
304 // Check validity of heap flags
305 assert(OldSize % min_alignment() == 0, "old space alignment");
306 assert(MaxHeapSize % max_alignment() == 0, "maximum heap alignment");
307 }
308
309 // Values set on the command line win over any ergonomically
310 // set command line parameters.
311 // Ergonomic choice of parameters are done before this
312 // method is called. Values for command line parameters such as NewSize
313 // and MaxNewSize feed those ergonomic choices into this method.
314 // This method makes the final generation sizings consistent with
315 // themselves and with overall heap sizings.
316 // In the absence of explicitly set command line flags, policies
317 // such as the use of NewRatio are used to size the generation.
318 void GenCollectorPolicy::initialize_size_info() {
319 CollectorPolicy::initialize_size_info();
320
321 // min_alignment() is used for alignment within a generation.
322 // There is additional alignment done down stream for some
323 // collectors that sometimes causes unwanted rounding up of
324 // generations sizes.
325
326 // Determine maximum size of gen0
327
328 size_t max_new_size = 0;
329 if (FLAG_IS_CMDLINE(MaxNewSize) || FLAG_IS_ERGO(MaxNewSize)) {
330 if (MaxNewSize < min_alignment()) {
331 max_new_size = min_alignment();
332 }
333 if (MaxNewSize >= max_heap_byte_size()) {
334 max_new_size = align_size_down(max_heap_byte_size() - min_alignment(),
335 min_alignment());
336 warning("MaxNewSize (" SIZE_FORMAT "k) is equal to or "
337 "greater than the entire heap (" SIZE_FORMAT "k). A "
338 "new generation size of " SIZE_FORMAT "k will be used.",
339 MaxNewSize/K, max_heap_byte_size()/K, max_new_size/K);
340 } else {
341 max_new_size = align_size_down(MaxNewSize, min_alignment());
342 }
343
344 // The case for FLAG_IS_ERGO(MaxNewSize) could be treated
345 // specially at this point to just use an ergonomically set
346 // MaxNewSize to set max_new_size. For cases with small
347 // heaps such a policy often did not work because the MaxNewSize
348 // was larger than the entire heap. The interpretation given
349 // to ergonomically set flags is that the flags are set
350 // by different collectors for their own special needs but
351 // are not allowed to badly shape the heap. This allows the
352 // different collectors to decide what's best for themselves
353 // without having to factor in the overall heap shape. It
354 // can be the case in the future that the collectors would
355 // only make "wise" ergonomics choices and this policy could
356 // just accept those choices. The choices currently made are
357 // not always "wise".
358 } else {
359 max_new_size = scale_by_NewRatio_aligned(max_heap_byte_size());
360 // Bound the maximum size by NewSize below (since it historically
361 // would have been NewSize and because the NewRatio calculation could
362 // yield a size that is too small) and bound it by MaxNewSize above.
363 // Ergonomics plays here by previously calculating the desired
364 // NewSize and MaxNewSize.
365 max_new_size = MIN2(MAX2(max_new_size, NewSize), MaxNewSize);
366 }
367 assert(max_new_size > 0, "All paths should set max_new_size");
368
369 // Given the maximum gen0 size, determine the initial and
370 // minimum gen0 sizes.
371
372 if (max_heap_byte_size() == min_heap_byte_size()) {
373 // The maximum and minimum heap sizes are the same so
374 // the generations minimum and initial must be the
375 // same as its maximum.
376 set_min_gen0_size(max_new_size);
377 set_initial_gen0_size(max_new_size);
378 set_max_gen0_size(max_new_size);
379 } else {
380 size_t desired_new_size = 0;
381 if (!FLAG_IS_DEFAULT(NewSize)) {
382 // If NewSize is set ergonomically (for example by cms), it
383 // would make sense to use it. If it is used, also use it
384 // to set the initial size. Although there is no reason
385 // the minimum size and the initial size have to be the same,
386 // the current implementation gets into trouble during the calculation
387 // of the tenured generation sizes if they are different.
388 // Note that this makes the initial size and the minimum size
389 // generally small compared to the NewRatio calculation.
390 _min_gen0_size = NewSize;
391 desired_new_size = NewSize;
392 max_new_size = MAX2(max_new_size, NewSize);
393 } else {
394 // For the case where NewSize is the default, use NewRatio
395 // to size the minimum and initial generation sizes.
396 // Use the default NewSize as the floor for these values. If
397 // NewRatio is overly large, the resulting sizes can be too
398 // small.
399 _min_gen0_size = MAX2(scale_by_NewRatio_aligned(min_heap_byte_size()),
400 NewSize);
401 desired_new_size =
402 MAX2(scale_by_NewRatio_aligned(initial_heap_byte_size()),
403 NewSize);
404 }
405
406 assert(_min_gen0_size > 0, "Sanity check");
407 set_initial_gen0_size(desired_new_size);
408 set_max_gen0_size(max_new_size);
409
410 // At this point the desirable initial and minimum sizes have been
411 // determined without regard to the maximum sizes.
412
413 // Bound the sizes by the corresponding overall heap sizes.
414 set_min_gen0_size(
415 bound_minus_alignment(_min_gen0_size, min_heap_byte_size()));
416 set_initial_gen0_size(
417 bound_minus_alignment(_initial_gen0_size, initial_heap_byte_size()));
418 set_max_gen0_size(
419 bound_minus_alignment(_max_gen0_size, max_heap_byte_size()));
420
421 // At this point all three sizes have been checked against the
422 // maximum sizes but have not been checked for consistency
423 // among the three.
424
425 // Final check min <= initial <= max
426 set_min_gen0_size(MIN2(_min_gen0_size, _max_gen0_size));
427 set_initial_gen0_size(
428 MAX2(MIN2(_initial_gen0_size, _max_gen0_size), _min_gen0_size));
429 set_min_gen0_size(MIN2(_min_gen0_size, _initial_gen0_size));
430 }
431
432 if (PrintGCDetails && Verbose) {
433 gclog_or_tty->print_cr("1: Minimum gen0 " SIZE_FORMAT " Initial gen0 "
434 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT,
435 min_gen0_size(), initial_gen0_size(), max_gen0_size());
436 }
437 }
438
439 // Call this method during the sizing of the gen1 to make
440 // adjustments to gen0 because of gen1 sizing policy. gen0 initially has
441 // the most freedom in sizing because it is done before the
442 // policy for gen1 is applied. Once gen1 policies have been applied,
443 // there may be conflicts in the shape of the heap and this method
444 // is used to make the needed adjustments. The application of the
445 // policies could be more sophisticated (iterative for example) but
446 // keeping it simple also seems a worthwhile goal.
447 bool TwoGenerationCollectorPolicy::adjust_gen0_sizes(size_t* gen0_size_ptr,
448 size_t* gen1_size_ptr,
449 const size_t heap_size,
450 const size_t min_gen1_size) {
451 bool result = false;
452
453 if ((*gen1_size_ptr + *gen0_size_ptr) > heap_size) {
454 if ((heap_size < (*gen0_size_ptr + min_gen1_size)) &&
455 (heap_size >= min_gen1_size + min_alignment())) {
456 // Adjust gen0 down to accommodate min_gen1_size
457 *gen0_size_ptr = heap_size - min_gen1_size;
458 *gen0_size_ptr =
459 MAX2((uintx)align_size_down(*gen0_size_ptr, min_alignment()),
460 min_alignment());
461 assert(*gen0_size_ptr > 0, "Min gen0 is too large");
462 result = true;
463 } else {
464 *gen1_size_ptr = heap_size - *gen0_size_ptr;
465 *gen1_size_ptr =
466 MAX2((uintx)align_size_down(*gen1_size_ptr, min_alignment()),
467 min_alignment());
468 }
469 }
470 return result;
471 }
472
473 // Minimum sizes of the generations may be different than
474 // the initial sizes. An inconsistently is permitted here
475 // in the total size that can be specified explicitly by
476 // command line specification of OldSize and NewSize and
477 // also a command line specification of -Xms. Issue a warning
478 // but allow the values to pass.
479
480 void TwoGenerationCollectorPolicy::initialize_size_info() {
481 GenCollectorPolicy::initialize_size_info();
482
483 // At this point the minimum, initial and maximum sizes
484 // of the overall heap and of gen0 have been determined.
485 // The maximum gen1 size can be determined from the maximum gen0
486 // and maximum heap size since no explicit flags exits
487 // for setting the gen1 maximum.
488 _max_gen1_size = max_heap_byte_size() - _max_gen0_size;
489 _max_gen1_size =
490 MAX2((uintx)align_size_down(_max_gen1_size, min_alignment()),
491 min_alignment());
492 // If no explicit command line flag has been set for the
493 // gen1 size, use what is left for gen1.
494 if (FLAG_IS_DEFAULT(OldSize) || FLAG_IS_ERGO(OldSize)) {
495 // The user has not specified any value or ergonomics
496 // has chosen a value (which may or may not be consistent
497 // with the overall heap size). In either case make
498 // the minimum, maximum and initial sizes consistent
499 // with the gen0 sizes and the overall heap sizes.
500 assert(min_heap_byte_size() > _min_gen0_size,
501 "gen0 has an unexpected minimum size");
502 set_min_gen1_size(min_heap_byte_size() - min_gen0_size());
503 set_min_gen1_size(
504 MAX2((uintx)align_size_down(_min_gen1_size, min_alignment()),
505 min_alignment()));
506 set_initial_gen1_size(initial_heap_byte_size() - initial_gen0_size());
507 set_initial_gen1_size(
508 MAX2((uintx)align_size_down(_initial_gen1_size, min_alignment()),
509 min_alignment()));
510
511 } else {
512 // It's been explicitly set on the command line. Use the
513 // OldSize and then determine the consequences.
514 set_min_gen1_size(OldSize);
515 set_initial_gen1_size(OldSize);
516
517 // If the user has explicitly set an OldSize that is inconsistent
518 // with other command line flags, issue a warning.
519 // The generation minimums and the overall heap mimimum should
520 // be within one heap alignment.
521 if ((_min_gen1_size + _min_gen0_size + min_alignment()) <
522 min_heap_byte_size()) {
523 warning("Inconsistency between minimum heap size and minimum "
524 "generation sizes: using minimum heap = " SIZE_FORMAT,
525 min_heap_byte_size());
526 }
527 if ((OldSize > _max_gen1_size)) {
528 warning("Inconsistency between maximum heap size and maximum "
529 "generation sizes: using maximum heap = " SIZE_FORMAT
530 " -XX:OldSize flag is being ignored",
531 max_heap_byte_size());
532 }
533 // If there is an inconsistency between the OldSize and the minimum and/or
534 // initial size of gen0, since OldSize was explicitly set, OldSize wins.
535 if (adjust_gen0_sizes(&_min_gen0_size, &_min_gen1_size,
536 min_heap_byte_size(), OldSize)) {
537 if (PrintGCDetails && Verbose) {
538 gclog_or_tty->print_cr("2: Minimum gen0 " SIZE_FORMAT " Initial gen0 "
539 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT,
540 min_gen0_size(), initial_gen0_size(), max_gen0_size());
541 }
542 }
543 // Initial size
544 if (adjust_gen0_sizes(&_initial_gen0_size, &_initial_gen1_size,
545 initial_heap_byte_size(), OldSize)) {
546 if (PrintGCDetails && Verbose) {
547 gclog_or_tty->print_cr("3: Minimum gen0 " SIZE_FORMAT " Initial gen0 "
548 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT,
549 min_gen0_size(), initial_gen0_size(), max_gen0_size());
550 }
551 }
552 }
553 // Enforce the maximum gen1 size.
554 set_min_gen1_size(MIN2(_min_gen1_size, _max_gen1_size));
555
556 // Check that min gen1 <= initial gen1 <= max gen1
557 set_initial_gen1_size(MAX2(_initial_gen1_size, _min_gen1_size));
558 set_initial_gen1_size(MIN2(_initial_gen1_size, _max_gen1_size));
559
560 if (PrintGCDetails && Verbose) {
561 gclog_or_tty->print_cr("Minimum gen1 " SIZE_FORMAT " Initial gen1 "
562 SIZE_FORMAT " Maximum gen1 " SIZE_FORMAT,
563 min_gen1_size(), initial_gen1_size(), max_gen1_size());
564 }
565 }
566
567 HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size,
568 bool is_tlab,
569 bool* gc_overhead_limit_was_exceeded) {
570 GenCollectedHeap *gch = GenCollectedHeap::heap();
571
572 debug_only(gch->check_for_valid_allocation_state());
573 assert(gch->no_gc_in_progress(), "Allocation during gc not allowed");
574
575 // In general gc_overhead_limit_was_exceeded should be false so
576 // set it so here and reset it to true only if the gc time
577 // limit is being exceeded as checked below.
578 *gc_overhead_limit_was_exceeded = false;
579
580 HeapWord* result = NULL;
581
582 // Loop until the allocation is satisified,
583 // or unsatisfied after GC.
584 for (int try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
585 HandleMark hm; // discard any handles allocated in each iteration
586
587 // First allocation attempt is lock-free.
588 Generation *gen0 = gch->get_gen(0);
589 assert(gen0->supports_inline_contig_alloc(),
590 "Otherwise, must do alloc within heap lock");
591 if (gen0->should_allocate(size, is_tlab)) {
592 result = gen0->par_allocate(size, is_tlab);
593 if (result != NULL) {
594 assert(gch->is_in_reserved(result), "result not in heap");
595 return result;
596 }
597 }
598 unsigned int gc_count_before; // read inside the Heap_lock locked region
599 {
600 MutexLocker ml(Heap_lock);
601 if (PrintGC && Verbose) {
602 gclog_or_tty->print_cr("TwoGenerationCollectorPolicy::mem_allocate_work:"
603 " attempting locked slow path allocation");
604 }
605 // Note that only large objects get a shot at being
606 // allocated in later generations.
607 bool first_only = ! should_try_older_generation_allocation(size);
608
609 result = gch->attempt_allocation(size, is_tlab, first_only);
610 if (result != NULL) {
611 assert(gch->is_in_reserved(result), "result not in heap");
612 return result;
613 }
614
615 if (GC_locker::is_active_and_needs_gc()) {
616 if (is_tlab) {
617 return NULL; // Caller will retry allocating individual object
618 }
619 if (!gch->is_maximal_no_gc()) {
620 // Try and expand heap to satisfy request
621 result = expand_heap_and_allocate(size, is_tlab);
622 // result could be null if we are out of space
623 if (result != NULL) {
624 return result;
625 }
626 }
627
628 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
629 return NULL; // we didn't get to do a GC and we didn't get any memory
630 }
631
632 // If this thread is not in a jni critical section, we stall
633 // the requestor until the critical section has cleared and
634 // GC allowed. When the critical section clears, a GC is
635 // initiated by the last thread exiting the critical section; so
636 // we retry the allocation sequence from the beginning of the loop,
637 // rather than causing more, now probably unnecessary, GC attempts.
638 JavaThread* jthr = JavaThread::current();
639 if (!jthr->in_critical()) {
640 MutexUnlocker mul(Heap_lock);
641 // Wait for JNI critical section to be exited
642 GC_locker::stall_until_clear();
643 gclocker_stalled_count += 1;
644 continue;
645 } else {
646 if (CheckJNICalls) {
647 fatal("Possible deadlock due to allocating while"
648 " in jni critical section");
649 }
650 return NULL;
651 }
652 }
653
654 // Read the gc count while the heap lock is held.
655 gc_count_before = Universe::heap()->total_collections();
656 }
657
658 VM_GenCollectForAllocation op(size,
659 is_tlab,
660 gc_count_before);
661 VMThread::execute(&op);
662 if (op.prologue_succeeded()) {
663 result = op.result();
664 if (op.gc_locked()) {
665 assert(result == NULL, "must be NULL if gc_locked() is true");
666 continue; // retry and/or stall as necessary
667 }
668
669 // Allocation has failed and a collection
670 // has been done. If the gc time limit was exceeded the
671 // this time, return NULL so that an out-of-memory
672 // will be thrown. Clear gc_overhead_limit_exceeded
673 // so that the overhead exceeded does not persist.
674
675 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
676 const bool softrefs_clear = all_soft_refs_clear();
677
678 if (limit_exceeded && softrefs_clear) {
679 *gc_overhead_limit_was_exceeded = true;
680 size_policy()->set_gc_overhead_limit_exceeded(false);
681 if (op.result() != NULL) {
682 CollectedHeap::fill_with_object(op.result(), size);
683 }
684 return NULL;
685 }
686 assert(result == NULL || gch->is_in_reserved(result),
687 "result not in heap");
688 return result;
689 }
690
691 // Give a warning if we seem to be looping forever.
692 if ((QueuedAllocationWarningCount > 0) &&
693 (try_count % QueuedAllocationWarningCount == 0)) {
694 warning("TwoGenerationCollectorPolicy::mem_allocate_work retries %d times \n\t"
695 " size=%d %s", try_count, size, is_tlab ? "(TLAB)" : "");
696 }
697 }
698 }
699
700 HeapWord* GenCollectorPolicy::expand_heap_and_allocate(size_t size,
701 bool is_tlab) {
702 GenCollectedHeap *gch = GenCollectedHeap::heap();
703 HeapWord* result = NULL;
704 for (int i = number_of_generations() - 1; i >= 0 && result == NULL; i--) {
705 Generation *gen = gch->get_gen(i);
706 if (gen->should_allocate(size, is_tlab)) {
707 result = gen->expand_and_allocate(size, is_tlab);
708 }
709 }
710 assert(result == NULL || gch->is_in_reserved(result), "result not in heap");
711 return result;
712 }
713
714 HeapWord* GenCollectorPolicy::satisfy_failed_allocation(size_t size,
715 bool is_tlab) {
716 GenCollectedHeap *gch = GenCollectedHeap::heap();
717 GCCauseSetter x(gch, GCCause::_allocation_failure);
718 HeapWord* result = NULL;
719
720 assert(size != 0, "Precondition violated");
721 if (GC_locker::is_active_and_needs_gc()) {
722 // GC locker is active; instead of a collection we will attempt
723 // to expand the heap, if there's room for expansion.
724 if (!gch->is_maximal_no_gc()) {
725 result = expand_heap_and_allocate(size, is_tlab);
726 }
727 return result; // could be null if we are out of space
728 } else if (!gch->incremental_collection_will_fail(false /* don't consult_young */)) {
729 // Do an incremental collection.
730 gch->do_collection(false /* full */,
731 false /* clear_all_soft_refs */,
732 size /* size */,
733 is_tlab /* is_tlab */,
734 number_of_generations() - 1 /* max_level */);
735 } else {
736 if (Verbose && PrintGCDetails) {
737 gclog_or_tty->print(" :: Trying full because partial may fail :: ");
738 }
739 // Try a full collection; see delta for bug id 6266275
740 // for the original code and why this has been simplified
741 // with from-space allocation criteria modified and
742 // such allocation moved out of the safepoint path.
743 gch->do_collection(true /* full */,
744 false /* clear_all_soft_refs */,
745 size /* size */,
746 is_tlab /* is_tlab */,
747 number_of_generations() - 1 /* max_level */);
748 }
749
750 result = gch->attempt_allocation(size, is_tlab, false /*first_only*/);
751
752 if (result != NULL) {
753 assert(gch->is_in_reserved(result), "result not in heap");
754 return result;
755 }
756
757 // OK, collection failed, try expansion.
758 result = expand_heap_and_allocate(size, is_tlab);
759 if (result != NULL) {
760 return result;
761 }
762
763 // If we reach this point, we're really out of memory. Try every trick
764 // we can to reclaim memory. Force collection of soft references. Force
765 // a complete compaction of the heap. Any additional methods for finding
766 // free memory should be here, especially if they are expensive. If this
767 // attempt fails, an OOM exception will be thrown.
768 {
769 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
770
771 gch->do_collection(true /* full */,
772 true /* clear_all_soft_refs */,
773 size /* size */,
774 is_tlab /* is_tlab */,
775 number_of_generations() - 1 /* max_level */);
776 }
777
778 result = gch->attempt_allocation(size, is_tlab, false /* first_only */);
779 if (result != NULL) {
780 assert(gch->is_in_reserved(result), "result not in heap");
781 return result;
782 }
783
784 assert(!should_clear_all_soft_refs(),
785 "Flag should have been handled and cleared prior to this point");
786
787 // What else? We might try synchronous finalization later. If the total
788 // space available is large enough for the allocation, then a more
789 // complete compaction phase than we've tried so far might be
790 // appropriate.
791 return NULL;
792 }
793
794 MetaWord* CollectorPolicy::satisfy_failed_metadata_allocation(
795 ClassLoaderData* loader_data,
796 size_t word_size,
797 Metaspace::MetadataType mdtype) {
798 uint loop_count = 0;
799 uint gc_count = 0;
800 uint full_gc_count = 0;
801
802 assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");
803
804 do {
805 MetaWord* result = NULL;
806 if (GC_locker::is_active_and_needs_gc()) {
807 // If the GC_locker is active, just expand and allocate.
808 // If that does not succeed, wait if this thread is not
809 // in a critical section itself.
810 result =
811 loader_data->metaspace_non_null()->expand_and_allocate(word_size,
812 mdtype);
813 if (result != NULL) {
814 return result;
815 }
816 JavaThread* jthr = JavaThread::current();
817 if (!jthr->in_critical()) {
818 // Wait for JNI critical section to be exited
819 GC_locker::stall_until_clear();
820 // The GC invoked by the last thread leaving the critical
821 // section will be a young collection and a full collection
822 // is (currently) needed for unloading classes so continue
823 // to the next iteration to get a full GC.
824 continue;
825 } else {
826 if (CheckJNICalls) {
827 fatal("Possible deadlock due to allocating while"
828 " in jni critical section");
829 }
830 return NULL;
831 }
832 }
833
834 { // Need lock to get self consistent gc_count's
835 MutexLocker ml(Heap_lock);
836 gc_count = Universe::heap()->total_collections();
837 full_gc_count = Universe::heap()->total_full_collections();
838 }
839
840 // Generate a VM operation
841 VM_CollectForMetadataAllocation op(loader_data,
842 word_size,
843 mdtype,
844 gc_count,
845 full_gc_count,
846 GCCause::_metadata_GC_threshold);
847 VMThread::execute(&op);
848
849 // If GC was locked out, try again. Check
850 // before checking success because the prologue
851 // could have succeeded and the GC still have
852 // been locked out.
853 if (op.gc_locked()) {
854 continue;
855 }
856
857 if (op.prologue_succeeded()) {
858 return op.result();
859 }
860 loop_count++;
861 if ((QueuedAllocationWarningCount > 0) &&
862 (loop_count % QueuedAllocationWarningCount == 0)) {
863 warning("satisfy_failed_metadata_allocation() retries %d times \n\t"
864 " size=%d", loop_count, word_size);
865 }
866 } while (true); // Until a GC is done
867 }
868
869 // Return true if any of the following is true:
870 // . the allocation won't fit into the current young gen heap
871 // . gc locker is occupied (jni critical section)
872 // . heap memory is tight -- the most recent previous collection
873 // was a full collection because a partial collection (would
874 // have) failed and is likely to fail again
875 bool GenCollectorPolicy::should_try_older_generation_allocation(
876 size_t word_size) const {
877 GenCollectedHeap* gch = GenCollectedHeap::heap();
878 size_t gen0_capacity = gch->get_gen(0)->capacity_before_gc();
879 return (word_size > heap_word_size(gen0_capacity))
880 || GC_locker::is_active_and_needs_gc()
881 || gch->incremental_collection_failed();
882 }
883
884
885 //
886 // MarkSweepPolicy methods
887 //
888
889 MarkSweepPolicy::MarkSweepPolicy() {
890 initialize_all();
891 }
892
893 void MarkSweepPolicy::initialize_generations() {
894 _generations = NEW_C_HEAP_ARRAY3(GenerationSpecPtr, number_of_generations(), mtGC, 0, AllocFailStrategy::RETURN_NULL);
895 if (_generations == NULL)
896 vm_exit_during_initialization("Unable to allocate gen spec");
897
898 if (UseParNewGC) {
899 _generations[0] = new GenerationSpec(Generation::ParNew, _initial_gen0_size, _max_gen0_size);
900 } else {
901 _generations[0] = new GenerationSpec(Generation::DefNew, _initial_gen0_size, _max_gen0_size);
902 }
903 _generations[1] = new GenerationSpec(Generation::MarkSweepCompact, _initial_gen1_size, _max_gen1_size);
904
905 if (_generations[0] == NULL || _generations[1] == NULL)
906 vm_exit_during_initialization("Unable to allocate gen spec");
907 }
908
909 void MarkSweepPolicy::initialize_gc_policy_counters() {
910 // initialize the policy counters - 2 collectors, 3 generations
911 if (UseParNewGC) {
912 _gc_policy_counters = new GCPolicyCounters("ParNew:MSC", 2, 3);
913 } else {
914 _gc_policy_counters = new GCPolicyCounters("Copy:MSC", 2, 3);
915 }
916 }