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