1 /*
2 * Copyright (c) 2001, 2016, 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/shared/adaptiveSizePolicy.hpp"
27 #include "gc/shared/cardTableRS.hpp"
28 #include "gc/shared/collectorPolicy.hpp"
29 #include "gc/shared/gcLocker.inline.hpp"
30 #include "gc/shared/gcPolicyCounters.hpp"
31 #include "gc/shared/genCollectedHeap.hpp"
32 #include "gc/shared/generationSpec.hpp"
33 #include "gc/shared/space.hpp"
34 #include "gc/shared/vmGCOperations.hpp"
35 #include "logging/log.hpp"
36 #include "memory/universe.hpp"
37 #include "runtime/arguments.hpp"
38 #include "runtime/globals_extension.hpp"
39 #include "runtime/handles.inline.hpp"
40 #include "runtime/java.hpp"
41 #include "runtime/thread.inline.hpp"
42 #include "runtime/vmThread.hpp"
43 #include "utilities/align.hpp"
44 #include "utilities/macros.hpp"
45
46 // CollectorPolicy methods
47
48 CollectorPolicy::CollectorPolicy() :
49 _space_alignment(0),
50 _heap_alignment(0),
51 _initial_heap_byte_size(InitialHeapSize),
52 _max_heap_byte_size(MaxHeapSize),
53 _min_heap_byte_size(Arguments::min_heap_size()),
54 _should_clear_all_soft_refs(false),
55 _all_soft_refs_clear(false)
56 {}
57
58 #ifdef ASSERT
59 void CollectorPolicy::assert_flags() {
60 assert(InitialHeapSize <= MaxHeapSize, "Ergonomics decided on incompatible initial and maximum heap sizes");
61 assert(InitialHeapSize % _heap_alignment == 0, "InitialHeapSize alignment");
62 assert(MaxHeapSize % _heap_alignment == 0, "MaxHeapSize alignment");
63 }
64
65 void CollectorPolicy::assert_size_info() {
66 assert(InitialHeapSize == _initial_heap_byte_size, "Discrepancy between InitialHeapSize flag and local storage");
67 assert(MaxHeapSize == _max_heap_byte_size, "Discrepancy between MaxHeapSize flag and local storage");
68 assert(_max_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible minimum and maximum heap sizes");
69 assert(_initial_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible initial and minimum heap sizes");
70 assert(_max_heap_byte_size >= _initial_heap_byte_size, "Ergonomics decided on incompatible initial and maximum heap sizes");
71 assert(_min_heap_byte_size % _heap_alignment == 0, "min_heap_byte_size alignment");
72 assert(_initial_heap_byte_size % _heap_alignment == 0, "initial_heap_byte_size alignment");
73 assert(_max_heap_byte_size % _heap_alignment == 0, "max_heap_byte_size alignment");
74 }
75 #endif // ASSERT
76
77 void CollectorPolicy::initialize_flags() {
78 assert(_space_alignment != 0, "Space alignment not set up properly");
79 assert(_heap_alignment != 0, "Heap alignment not set up properly");
80 assert(_heap_alignment >= _space_alignment,
81 "heap_alignment: " SIZE_FORMAT " less than space_alignment: " SIZE_FORMAT,
82 _heap_alignment, _space_alignment);
83 assert(_heap_alignment % _space_alignment == 0,
84 "heap_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT,
85 _heap_alignment, _space_alignment);
86
87 if (FLAG_IS_CMDLINE(MaxHeapSize)) {
88 if (FLAG_IS_CMDLINE(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {
89 vm_exit_during_initialization("Initial heap size set to a larger value than the maximum heap size");
90 }
91 if (_min_heap_byte_size != 0 && MaxHeapSize < _min_heap_byte_size) {
92 vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified");
93 }
94 }
95
96 // Check heap parameter properties
97 if (MaxHeapSize < 2 * M) {
98 vm_exit_during_initialization("Too small maximum heap");
99 }
100 if (InitialHeapSize < M) {
101 vm_exit_during_initialization("Too small initial heap");
102 }
103 if (_min_heap_byte_size < M) {
104 vm_exit_during_initialization("Too small minimum heap");
105 }
106
107 // User inputs from -Xmx and -Xms must be aligned
108 _min_heap_byte_size = align_up(_min_heap_byte_size, _heap_alignment);
109 size_t aligned_initial_heap_size = align_up(InitialHeapSize, _heap_alignment);
110 size_t aligned_max_heap_size = align_up(MaxHeapSize, _heap_alignment);
111
112 // Write back to flags if the values changed
113 if (aligned_initial_heap_size != InitialHeapSize) {
114 FLAG_SET_ERGO(size_t, InitialHeapSize, aligned_initial_heap_size);
115 }
116 if (aligned_max_heap_size != MaxHeapSize) {
117 FLAG_SET_ERGO(size_t, MaxHeapSize, aligned_max_heap_size);
118 }
119
120 if (FLAG_IS_CMDLINE(InitialHeapSize) && _min_heap_byte_size != 0 &&
121 InitialHeapSize < _min_heap_byte_size) {
122 vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified");
123 }
124 if (!FLAG_IS_DEFAULT(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {
125 FLAG_SET_ERGO(size_t, MaxHeapSize, InitialHeapSize);
126 } else if (!FLAG_IS_DEFAULT(MaxHeapSize) && InitialHeapSize > MaxHeapSize) {
127 FLAG_SET_ERGO(size_t, InitialHeapSize, MaxHeapSize);
128 if (InitialHeapSize < _min_heap_byte_size) {
129 _min_heap_byte_size = InitialHeapSize;
130 }
131 }
132
133 _initial_heap_byte_size = InitialHeapSize;
134 _max_heap_byte_size = MaxHeapSize;
135
136 FLAG_SET_ERGO(size_t, MinHeapDeltaBytes, align_up(MinHeapDeltaBytes, _space_alignment));
137
138 DEBUG_ONLY(CollectorPolicy::assert_flags();)
139 }
140
141 void CollectorPolicy::initialize_size_info() {
142 log_debug(gc, heap)("Minimum heap " SIZE_FORMAT " Initial heap " SIZE_FORMAT " Maximum heap " SIZE_FORMAT,
143 _min_heap_byte_size, _initial_heap_byte_size, _max_heap_byte_size);
144
145 DEBUG_ONLY(CollectorPolicy::assert_size_info();)
146 }
147
148 bool CollectorPolicy::use_should_clear_all_soft_refs(bool v) {
149 bool result = _should_clear_all_soft_refs;
150 set_should_clear_all_soft_refs(false);
151 return result;
152 }
153
154 CardTableRS* CollectorPolicy::create_rem_set(MemRegion whole_heap) {
155 return new CardTableRS(whole_heap);
156 }
157
158 void CollectorPolicy::cleared_all_soft_refs() {
159 _all_soft_refs_clear = true;
160 }
161
162 size_t CollectorPolicy::compute_heap_alignment() {
163 // The card marking array and the offset arrays for old generations are
164 // committed in os pages as well. Make sure they are entirely full (to
165 // avoid partial page problems), e.g. if 512 bytes heap corresponds to 1
166 // byte entry and the os page size is 4096, the maximum heap size should
167 // be 512*4096 = 2MB aligned.
168
169 size_t alignment = CardTableRS::ct_max_alignment_constraint();
170
171 if (UseLargePages) {
172 // In presence of large pages we have to make sure that our
173 // alignment is large page aware.
174 alignment = lcm(os::large_page_size(), alignment);
175 }
176
177 return alignment;
178 }
179
180 // GenCollectorPolicy methods
181
182 GenCollectorPolicy::GenCollectorPolicy() :
183 _min_young_size(0),
184 _initial_young_size(0),
185 _max_young_size(0),
186 _min_old_size(0),
187 _initial_old_size(0),
188 _max_old_size(0),
189 _gen_alignment(0),
190 _young_gen_spec(NULL),
191 _old_gen_spec(NULL),
192 _size_policy(NULL)
193 {}
194
195 size_t GenCollectorPolicy::scale_by_NewRatio_aligned(size_t base_size) {
196 return align_down_bounded(base_size / (NewRatio + 1), _gen_alignment);
197 }
198
199 size_t GenCollectorPolicy::bound_minus_alignment(size_t desired_size,
200 size_t maximum_size) {
201 size_t max_minus = maximum_size - _gen_alignment;
202 return desired_size < max_minus ? desired_size : max_minus;
203 }
204
205
206 void GenCollectorPolicy::initialize_size_policy(size_t init_eden_size,
207 size_t init_promo_size,
208 size_t init_survivor_size) {
209 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
210 _size_policy = new AdaptiveSizePolicy(init_eden_size,
211 init_promo_size,
212 init_survivor_size,
213 max_gc_pause_sec,
214 GCTimeRatio);
215 }
216
217 void GenCollectorPolicy::cleared_all_soft_refs() {
218 // If near gc overhear limit, continue to clear SoftRefs. SoftRefs may
219 // have been cleared in the last collection but if the gc overhear
220 // limit continues to be near, SoftRefs should still be cleared.
221 if (size_policy() != NULL) {
222 _should_clear_all_soft_refs = size_policy()->gc_overhead_limit_near();
223 }
224
225 CollectorPolicy::cleared_all_soft_refs();
226 }
227
228 size_t GenCollectorPolicy::young_gen_size_lower_bound() {
229 // The young generation must be aligned and have room for eden + two survivors
230 return align_up(3 * _space_alignment, _gen_alignment);
231 }
232
233 size_t GenCollectorPolicy::old_gen_size_lower_bound() {
234 return align_up(_space_alignment, _gen_alignment);
235 }
236
237 #ifdef ASSERT
238 void GenCollectorPolicy::assert_flags() {
239 CollectorPolicy::assert_flags();
240 assert(NewSize >= _min_young_size, "Ergonomics decided on a too small young gen size");
241 assert(NewSize <= MaxNewSize, "Ergonomics decided on incompatible initial and maximum young gen sizes");
242 assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young gen and heap sizes");
243 assert(NewSize % _gen_alignment == 0, "NewSize alignment");
244 assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize % _gen_alignment == 0, "MaxNewSize alignment");
245 assert(OldSize + NewSize <= MaxHeapSize, "Ergonomics decided on incompatible generation and heap sizes");
246 assert(OldSize % _gen_alignment == 0, "OldSize alignment");
247 }
248
249 void GenCollectorPolicy::assert_size_info() {
250 CollectorPolicy::assert_size_info();
251 // GenCollectorPolicy::initialize_size_info may update the MaxNewSize
252 assert(MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young and heap sizes");
253 assert(NewSize == _initial_young_size, "Discrepancy between NewSize flag and local storage");
254 assert(MaxNewSize == _max_young_size, "Discrepancy between MaxNewSize flag and local storage");
255 assert(OldSize == _initial_old_size, "Discrepancy between OldSize flag and local storage");
256 assert(_min_young_size <= _initial_young_size, "Ergonomics decided on incompatible minimum and initial young gen sizes");
257 assert(_initial_young_size <= _max_young_size, "Ergonomics decided on incompatible initial and maximum young gen sizes");
258 assert(_min_young_size % _gen_alignment == 0, "_min_young_size alignment");
259 assert(_initial_young_size % _gen_alignment == 0, "_initial_young_size alignment");
260 assert(_max_young_size % _gen_alignment == 0, "_max_young_size alignment");
261 assert(_min_young_size <= bound_minus_alignment(_min_young_size, _min_heap_byte_size),
262 "Ergonomics made minimum young generation larger than minimum heap");
263 assert(_initial_young_size <= bound_minus_alignment(_initial_young_size, _initial_heap_byte_size),
264 "Ergonomics made initial young generation larger than initial heap");
265 assert(_max_young_size <= bound_minus_alignment(_max_young_size, _max_heap_byte_size),
266 "Ergonomics made maximum young generation lager than maximum heap");
267 assert(_min_old_size <= _initial_old_size, "Ergonomics decided on incompatible minimum and initial old gen sizes");
268 assert(_initial_old_size <= _max_old_size, "Ergonomics decided on incompatible initial and maximum old gen sizes");
269 assert(_max_old_size % _gen_alignment == 0, "_max_old_size alignment");
270 assert(_initial_old_size % _gen_alignment == 0, "_initial_old_size alignment");
271 assert(_max_heap_byte_size <= (_max_young_size + _max_old_size), "Total maximum heap sizes must be sum of generation maximum sizes");
272 assert(_min_young_size + _min_old_size <= _min_heap_byte_size, "Minimum generation sizes exceed minimum heap size");
273 assert(_initial_young_size + _initial_old_size == _initial_heap_byte_size, "Initial generation sizes should match initial heap size");
274 assert(_max_young_size + _max_old_size == _max_heap_byte_size, "Maximum generation sizes should match maximum heap size");
275 }
276 #endif // ASSERT
277
278 void GenCollectorPolicy::initialize_flags() {
279 CollectorPolicy::initialize_flags();
280
281 assert(_gen_alignment != 0, "Generation alignment not set up properly");
282 assert(_heap_alignment >= _gen_alignment,
283 "heap_alignment: " SIZE_FORMAT " less than gen_alignment: " SIZE_FORMAT,
284 _heap_alignment, _gen_alignment);
285 assert(_gen_alignment % _space_alignment == 0,
286 "gen_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT,
287 _gen_alignment, _space_alignment);
288 assert(_heap_alignment % _gen_alignment == 0,
289 "heap_alignment: " SIZE_FORMAT " not aligned by gen_alignment: " SIZE_FORMAT,
290 _heap_alignment, _gen_alignment);
291
292 // All generational heaps have a young gen; handle those flags here
293
294 // Make sure the heap is large enough for two generations
295 size_t smallest_new_size = young_gen_size_lower_bound();
296 size_t smallest_heap_size = align_up(smallest_new_size + old_gen_size_lower_bound(),
297 _heap_alignment);
298 if (MaxHeapSize < smallest_heap_size) {
299 FLAG_SET_ERGO(size_t, MaxHeapSize, smallest_heap_size);
300 _max_heap_byte_size = MaxHeapSize;
301 }
302 // If needed, synchronize _min_heap_byte size and _initial_heap_byte_size
303 if (_min_heap_byte_size < smallest_heap_size) {
304 _min_heap_byte_size = smallest_heap_size;
305 if (InitialHeapSize < _min_heap_byte_size) {
306 FLAG_SET_ERGO(size_t, InitialHeapSize, smallest_heap_size);
307 _initial_heap_byte_size = smallest_heap_size;
308 }
309 }
310
311 // Make sure NewSize allows an old generation to fit even if set on the command line
312 if (FLAG_IS_CMDLINE(NewSize) && NewSize >= _initial_heap_byte_size) {
313 log_warning(gc, ergo)("NewSize was set larger than initial heap size, will use initial heap size.");
314 FLAG_SET_ERGO(size_t, NewSize, bound_minus_alignment(NewSize, _initial_heap_byte_size));
315 }
316
317 // Now take the actual NewSize into account. We will silently increase NewSize
318 // if the user specified a smaller or unaligned value.
319 size_t bounded_new_size = bound_minus_alignment(NewSize, MaxHeapSize);
320 bounded_new_size = MAX2(smallest_new_size, align_down(bounded_new_size, _gen_alignment));
321 if (bounded_new_size != NewSize) {
322 FLAG_SET_ERGO(size_t, NewSize, bounded_new_size);
323 }
324 _min_young_size = smallest_new_size;
325 _initial_young_size = NewSize;
326
327 if (!FLAG_IS_DEFAULT(MaxNewSize)) {
328 if (MaxNewSize >= MaxHeapSize) {
329 // Make sure there is room for an old generation
330 size_t smaller_max_new_size = MaxHeapSize - _gen_alignment;
331 if (FLAG_IS_CMDLINE(MaxNewSize)) {
332 log_warning(gc, ergo)("MaxNewSize (" SIZE_FORMAT "k) is equal to or greater than the entire "
333 "heap (" SIZE_FORMAT "k). A new max generation size of " SIZE_FORMAT "k will be used.",
334 MaxNewSize/K, MaxHeapSize/K, smaller_max_new_size/K);
335 }
336 FLAG_SET_ERGO(size_t, MaxNewSize, smaller_max_new_size);
337 if (NewSize > MaxNewSize) {
338 FLAG_SET_ERGO(size_t, NewSize, MaxNewSize);
339 _initial_young_size = NewSize;
340 }
341 } else if (MaxNewSize < _initial_young_size) {
342 FLAG_SET_ERGO(size_t, MaxNewSize, _initial_young_size);
343 } else if (!is_aligned(MaxNewSize, _gen_alignment)) {
344 FLAG_SET_ERGO(size_t, MaxNewSize, align_down(MaxNewSize, _gen_alignment));
345 }
346 _max_young_size = MaxNewSize;
347 }
348
349 if (NewSize > MaxNewSize) {
350 // At this point this should only happen if the user specifies a large NewSize and/or
351 // a small (but not too small) MaxNewSize.
352 if (FLAG_IS_CMDLINE(MaxNewSize)) {
353 log_warning(gc, ergo)("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "
354 "A new max generation size of " SIZE_FORMAT "k will be used.",
355 NewSize/K, MaxNewSize/K, NewSize/K);
356 }
357 FLAG_SET_ERGO(size_t, MaxNewSize, NewSize);
358 _max_young_size = MaxNewSize;
359 }
360
361 if (SurvivorRatio < 1 || NewRatio < 1) {
362 vm_exit_during_initialization("Invalid young gen ratio specified");
363 }
364
365 if (OldSize < old_gen_size_lower_bound()) {
366 FLAG_SET_ERGO(size_t, OldSize, old_gen_size_lower_bound());
367 }
368 if (!is_aligned(OldSize, _gen_alignment)) {
369 FLAG_SET_ERGO(size_t, OldSize, align_down(OldSize, _gen_alignment));
370 }
371
372 if (FLAG_IS_CMDLINE(OldSize) && FLAG_IS_DEFAULT(MaxHeapSize)) {
373 // NewRatio will be used later to set the young generation size so we use
374 // it to calculate how big the heap should be based on the requested OldSize
375 // and NewRatio.
376 assert(NewRatio > 0, "NewRatio should have been set up earlier");
377 size_t calculated_heapsize = (OldSize / NewRatio) * (NewRatio + 1);
378
379 calculated_heapsize = align_up(calculated_heapsize, _heap_alignment);
380 FLAG_SET_ERGO(size_t, MaxHeapSize, calculated_heapsize);
381 _max_heap_byte_size = MaxHeapSize;
382 FLAG_SET_ERGO(size_t, InitialHeapSize, calculated_heapsize);
383 _initial_heap_byte_size = InitialHeapSize;
384 }
385
386 // Adjust NewSize and OldSize or MaxHeapSize to match each other
387 if (NewSize + OldSize > MaxHeapSize) {
388 if (FLAG_IS_CMDLINE(MaxHeapSize)) {
389 // Somebody has set a maximum heap size with the intention that we should not
390 // exceed it. Adjust New/OldSize as necessary.
391 size_t calculated_size = NewSize + OldSize;
392 double shrink_factor = (double) MaxHeapSize / calculated_size;
393 size_t smaller_new_size = align_down((size_t)(NewSize * shrink_factor), _gen_alignment);
394 FLAG_SET_ERGO(size_t, NewSize, MAX2(young_gen_size_lower_bound(), smaller_new_size));
395 _initial_young_size = NewSize;
396
397 // OldSize is already aligned because above we aligned MaxHeapSize to
398 // _heap_alignment, and we just made sure that NewSize is aligned to
399 // _gen_alignment. In initialize_flags() we verified that _heap_alignment
400 // is a multiple of _gen_alignment.
401 FLAG_SET_ERGO(size_t, OldSize, MaxHeapSize - NewSize);
402 } else {
403 FLAG_SET_ERGO(size_t, MaxHeapSize, align_up(NewSize + OldSize, _heap_alignment));
404 _max_heap_byte_size = MaxHeapSize;
405 }
406 }
407
408 // Update NewSize, if possible, to avoid sizing the young gen too small when only
409 // OldSize is set on the command line.
410 if (FLAG_IS_CMDLINE(OldSize) && !FLAG_IS_CMDLINE(NewSize)) {
411 if (OldSize < _initial_heap_byte_size) {
412 size_t new_size = _initial_heap_byte_size - OldSize;
413 // Need to compare against the flag value for max since _max_young_size
414 // might not have been set yet.
415 if (new_size >= _min_young_size && new_size <= MaxNewSize) {
416 FLAG_SET_ERGO(size_t, NewSize, new_size);
417 _initial_young_size = NewSize;
418 }
419 }
420 }
421
422 always_do_update_barrier = UseConcMarkSweepGC;
423
424 DEBUG_ONLY(GenCollectorPolicy::assert_flags();)
425 }
426
427 // Values set on the command line win over any ergonomically
428 // set command line parameters.
429 // Ergonomic choice of parameters are done before this
430 // method is called. Values for command line parameters such as NewSize
431 // and MaxNewSize feed those ergonomic choices into this method.
432 // This method makes the final generation sizings consistent with
433 // themselves and with overall heap sizings.
434 // In the absence of explicitly set command line flags, policies
435 // such as the use of NewRatio are used to size the generation.
436
437 // Minimum sizes of the generations may be different than
438 // the initial sizes. An inconsistency is permitted here
439 // in the total size that can be specified explicitly by
440 // command line specification of OldSize and NewSize and
441 // also a command line specification of -Xms. Issue a warning
442 // but allow the values to pass.
443 void GenCollectorPolicy::initialize_size_info() {
444 CollectorPolicy::initialize_size_info();
445
446 _initial_young_size = NewSize;
447 _max_young_size = MaxNewSize;
448 _initial_old_size = OldSize;
449
450 // Determine maximum size of the young generation.
451
452 if (FLAG_IS_DEFAULT(MaxNewSize)) {
453 _max_young_size = scale_by_NewRatio_aligned(_max_heap_byte_size);
454 // Bound the maximum size by NewSize below (since it historically
455 // would have been NewSize and because the NewRatio calculation could
456 // yield a size that is too small) and bound it by MaxNewSize above.
457 // Ergonomics plays here by previously calculating the desired
458 // NewSize and MaxNewSize.
459 _max_young_size = MIN2(MAX2(_max_young_size, _initial_young_size), MaxNewSize);
460 }
461
462 // Given the maximum young size, determine the initial and
463 // minimum young sizes.
464
465 if (_max_heap_byte_size == _initial_heap_byte_size) {
466 // The maximum and initial heap sizes are the same so the generation's
467 // initial size must be the same as it maximum size. Use NewSize as the
468 // size if set on command line.
469 _max_young_size = FLAG_IS_CMDLINE(NewSize) ? NewSize : _max_young_size;
470 _initial_young_size = _max_young_size;
471
472 // Also update the minimum size if min == initial == max.
473 if (_max_heap_byte_size == _min_heap_byte_size) {
474 _min_young_size = _max_young_size;
475 }
476 } else {
477 if (FLAG_IS_CMDLINE(NewSize)) {
478 // If NewSize is set on the command line, we should use it as
479 // the initial size, but make sure it is within the heap bounds.
480 _initial_young_size =
481 MIN2(_max_young_size, bound_minus_alignment(NewSize, _initial_heap_byte_size));
482 _min_young_size = bound_minus_alignment(_initial_young_size, _min_heap_byte_size);
483 } else {
484 // For the case where NewSize is not set on the command line, use
485 // NewRatio to size the initial generation size. Use the current
486 // NewSize as the floor, because if NewRatio is overly large, the resulting
487 // size can be too small.
488 _initial_young_size =
489 MIN2(_max_young_size, MAX2(scale_by_NewRatio_aligned(_initial_heap_byte_size), NewSize));
490 }
491 }
492
493 log_trace(gc, heap)("1: Minimum young " SIZE_FORMAT " Initial young " SIZE_FORMAT " Maximum young " SIZE_FORMAT,
494 _min_young_size, _initial_young_size, _max_young_size);
495
496 // At this point the minimum, initial and maximum sizes
497 // of the overall heap and of the young generation have been determined.
498 // The maximum old size can be determined from the maximum young
499 // and maximum heap size since no explicit flags exist
500 // for setting the old generation maximum.
501 _max_old_size = MAX2(_max_heap_byte_size - _max_young_size, _gen_alignment);
502
503 // If no explicit command line flag has been set for the
504 // old generation size, use what is left.
505 if (!FLAG_IS_CMDLINE(OldSize)) {
506 // The user has not specified any value but the ergonomics
507 // may have chosen a value (which may or may not be consistent
508 // with the overall heap size). In either case make
509 // the minimum, maximum and initial sizes consistent
510 // with the young sizes and the overall heap sizes.
511 _min_old_size = _gen_alignment;
512 _initial_old_size = MIN2(_max_old_size, MAX2(_initial_heap_byte_size - _initial_young_size, _min_old_size));
513 // _max_old_size has already been made consistent above.
514 } else {
515 // OldSize has been explicitly set on the command line. Use it
516 // for the initial size but make sure the minimum allow a young
517 // generation to fit as well.
518 // If the user has explicitly set an OldSize that is inconsistent
519 // with other command line flags, issue a warning.
520 // The generation minimums and the overall heap minimum should
521 // be within one generation alignment.
522 if (_initial_old_size > _max_old_size) {
523 log_warning(gc, ergo)("Inconsistency between maximum heap size and maximum "
524 "generation sizes: using maximum heap = " SIZE_FORMAT
525 ", -XX:OldSize flag is being ignored",
526 _max_heap_byte_size);
527 _initial_old_size = _max_old_size;
528 }
529
530 _min_old_size = MIN2(_initial_old_size, _min_heap_byte_size - _min_young_size);
531 }
532
533 // The initial generation sizes should match the initial heap size,
534 // if not issue a warning and resize the generations. This behavior
535 // differs from JDK8 where the generation sizes have higher priority
536 // than the initial heap size.
537 if ((_initial_old_size + _initial_young_size) != _initial_heap_byte_size) {
538 log_warning(gc, ergo)("Inconsistency between generation sizes and heap size, resizing "
539 "the generations to fit the heap.");
540
541 size_t desired_young_size = _initial_heap_byte_size - _initial_old_size;
542 if (_initial_heap_byte_size < _initial_old_size) {
543 // Old want all memory, use minimum for young and rest for old
544 _initial_young_size = _min_young_size;
545 _initial_old_size = _initial_heap_byte_size - _min_young_size;
546 } else if (desired_young_size > _max_young_size) {
547 // Need to increase both young and old generation
548 _initial_young_size = _max_young_size;
549 _initial_old_size = _initial_heap_byte_size - _max_young_size;
550 } else if (desired_young_size < _min_young_size) {
551 // Need to decrease both young and old generation
552 _initial_young_size = _min_young_size;
553 _initial_old_size = _initial_heap_byte_size - _min_young_size;
554 } else {
555 // The young generation boundaries allow us to only update the
556 // young generation.
557 _initial_young_size = desired_young_size;
558 }
559
560 log_trace(gc, heap)("2: Minimum young " SIZE_FORMAT " Initial young " SIZE_FORMAT " Maximum young " SIZE_FORMAT,
561 _min_young_size, _initial_young_size, _max_young_size);
562 }
563
564 // Write back to flags if necessary.
565 if (NewSize != _initial_young_size) {
566 FLAG_SET_ERGO(size_t, NewSize, _initial_young_size);
567 }
568
569 if (MaxNewSize != _max_young_size) {
570 FLAG_SET_ERGO(size_t, MaxNewSize, _max_young_size);
571 }
572
573 if (OldSize != _initial_old_size) {
574 FLAG_SET_ERGO(size_t, OldSize, _initial_old_size);
575 }
576
577 log_trace(gc, heap)("Minimum old " SIZE_FORMAT " Initial old " SIZE_FORMAT " Maximum old " SIZE_FORMAT,
578 _min_old_size, _initial_old_size, _max_old_size);
579
580 DEBUG_ONLY(GenCollectorPolicy::assert_size_info();)
581 }
582
583 HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size,
584 bool is_tlab,
585 bool* gc_overhead_limit_was_exceeded) {
586 GenCollectedHeap *gch = GenCollectedHeap::heap();
587
588 debug_only(gch->check_for_valid_allocation_state());
589 assert(gch->no_gc_in_progress(), "Allocation during gc not allowed");
590
591 // In general gc_overhead_limit_was_exceeded should be false so
592 // set it so here and reset it to true only if the gc time
593 // limit is being exceeded as checked below.
594 *gc_overhead_limit_was_exceeded = false;
595
596 HeapWord* result = NULL;
597
598 // Loop until the allocation is satisfied, or unsatisfied after GC.
599 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
600 HandleMark hm; // Discard any handles allocated in each iteration.
601
602 // First allocation attempt is lock-free.
603 Generation *young = gch->young_gen();
604 assert(young->supports_inline_contig_alloc(),
605 "Otherwise, must do alloc within heap lock");
606 if (young->should_allocate(size, is_tlab)) {
607 result = young->par_allocate(size, is_tlab);
608 if (result != NULL) {
609 assert(gch->is_in_reserved(result), "result not in heap");
610 return result;
611 }
612 }
613 uint gc_count_before; // Read inside the Heap_lock locked region.
614 {
615 MutexLocker ml(Heap_lock);
616 log_trace(gc, alloc)("GenCollectorPolicy::mem_allocate_work: attempting locked slow path allocation");
617 // Note that only large objects get a shot at being
618 // allocated in later generations.
619 bool first_only = ! should_try_older_generation_allocation(size);
620
621 result = gch->attempt_allocation(size, is_tlab, first_only);
622 if (result != NULL) {
623 assert(gch->is_in_reserved(result), "result not in heap");
624 return result;
625 }
626
627 if (GCLocker::is_active_and_needs_gc()) {
628 if (is_tlab) {
629 return NULL; // Caller will retry allocating individual object.
630 }
631 if (!gch->is_maximal_no_gc()) {
632 // Try and expand heap to satisfy request.
633 result = expand_heap_and_allocate(size, is_tlab);
634 // Result could be null if we are out of space.
635 if (result != NULL) {
636 return result;
637 }
638 }
639
640 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
641 return NULL; // We didn't get to do a GC and we didn't get any memory.
642 }
643
644 // If this thread is not in a jni critical section, we stall
645 // the requestor until the critical section has cleared and
646 // GC allowed. When the critical section clears, a GC is
647 // initiated by the last thread exiting the critical section; so
648 // we retry the allocation sequence from the beginning of the loop,
649 // rather than causing more, now probably unnecessary, GC attempts.
650 JavaThread* jthr = JavaThread::current();
651 if (!jthr->in_critical()) {
652 MutexUnlocker mul(Heap_lock);
653 // Wait for JNI critical section to be exited
654 GCLocker::stall_until_clear();
655 gclocker_stalled_count += 1;
656 continue;
657 } else {
658 if (CheckJNICalls) {
659 fatal("Possible deadlock due to allocating while"
660 " in jni critical section");
661 }
662 return NULL;
663 }
664 }
665
666 // Read the gc count while the heap lock is held.
667 gc_count_before = gch->total_collections();
668 }
669
670 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
671 VMThread::execute(&op);
672 if (op.prologue_succeeded()) {
673 result = op.result();
674 if (op.gc_locked()) {
675 assert(result == NULL, "must be NULL if gc_locked() is true");
676 continue; // Retry and/or stall as necessary.
677 }
678
679 // Allocation has failed and a collection
680 // has been done. If the gc time limit was exceeded the
681 // this time, return NULL so that an out-of-memory
682 // will be thrown. Clear gc_overhead_limit_exceeded
683 // so that the overhead exceeded does not persist.
684
685 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
686 const bool softrefs_clear = all_soft_refs_clear();
687
688 if (limit_exceeded && softrefs_clear) {
689 *gc_overhead_limit_was_exceeded = true;
690 size_policy()->set_gc_overhead_limit_exceeded(false);
691 if (op.result() != NULL) {
692 CollectedHeap::fill_with_object(op.result(), size);
693 }
694 return NULL;
695 }
696 assert(result == NULL || gch->is_in_reserved(result),
697 "result not in heap");
698 return result;
699 }
700
701 // Give a warning if we seem to be looping forever.
702 if ((QueuedAllocationWarningCount > 0) &&
703 (try_count % QueuedAllocationWarningCount == 0)) {
704 log_warning(gc, ergo)("GenCollectorPolicy::mem_allocate_work retries %d times,"
705 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
706 }
707 }
708 }
709
710 HeapWord* GenCollectorPolicy::expand_heap_and_allocate(size_t size,
711 bool is_tlab) {
712 GenCollectedHeap *gch = GenCollectedHeap::heap();
713 HeapWord* result = NULL;
714 Generation *old = gch->old_gen();
715 if (old->should_allocate(size, is_tlab)) {
716 result = old->expand_and_allocate(size, is_tlab);
717 }
718 if (result == NULL) {
719 Generation *young = gch->young_gen();
720 if (young->should_allocate(size, is_tlab)) {
721 result = young->expand_and_allocate(size, is_tlab);
722 }
723 }
724 assert(result == NULL || gch->is_in_reserved(result), "result not in heap");
725 return result;
726 }
727
728 HeapWord* GenCollectorPolicy::satisfy_failed_allocation(size_t size,
729 bool is_tlab) {
730 GenCollectedHeap *gch = GenCollectedHeap::heap();
731 GCCauseSetter x(gch, GCCause::_allocation_failure);
732 HeapWord* result = NULL;
733
734 assert(size != 0, "Precondition violated");
735 if (GCLocker::is_active_and_needs_gc()) {
736 // GC locker is active; instead of a collection we will attempt
737 // to expand the heap, if there's room for expansion.
738 if (!gch->is_maximal_no_gc()) {
739 result = expand_heap_and_allocate(size, is_tlab);
740 }
741 return result; // Could be null if we are out of space.
742 } else if (!gch->incremental_collection_will_fail(false /* don't consult_young */)) {
743 // Do an incremental collection.
744 gch->do_collection(false, // full
745 false, // clear_all_soft_refs
746 size, // size
747 is_tlab, // is_tlab
748 GenCollectedHeap::OldGen); // max_generation
749 } else {
750 log_trace(gc)(" :: Trying full because partial may fail :: ");
751 // Try a full collection; see delta for bug id 6266275
752 // for the original code and why this has been simplified
753 // with from-space allocation criteria modified and
754 // such allocation moved out of the safepoint path.
755 gch->do_collection(true, // full
756 false, // clear_all_soft_refs
757 size, // size
758 is_tlab, // is_tlab
759 GenCollectedHeap::OldGen); // max_generation
760 }
761
762 result = gch->attempt_allocation(size, is_tlab, false /*first_only*/);
763
764 if (result != NULL) {
765 assert(gch->is_in_reserved(result), "result not in heap");
766 return result;
767 }
768
769 // OK, collection failed, try expansion.
770 result = expand_heap_and_allocate(size, is_tlab);
771 if (result != NULL) {
772 return result;
773 }
774
775 // If we reach this point, we're really out of memory. Try every trick
776 // we can to reclaim memory. Force collection of soft references. Force
777 // a complete compaction of the heap. Any additional methods for finding
778 // free memory should be here, especially if they are expensive. If this
779 // attempt fails, an OOM exception will be thrown.
780 {
781 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
782
783 gch->do_collection(true, // full
784 true, // clear_all_soft_refs
785 size, // size
786 is_tlab, // is_tlab
787 GenCollectedHeap::OldGen); // max_generation
788 }
789
790 result = gch->attempt_allocation(size, is_tlab, false /* first_only */);
791 if (result != NULL) {
792 assert(gch->is_in_reserved(result), "result not in heap");
793 return result;
794 }
795
796 assert(!should_clear_all_soft_refs(),
797 "Flag should have been handled and cleared prior to this point");
798
799 // What else? We might try synchronous finalization later. If the total
800 // space available is large enough for the allocation, then a more
801 // complete compaction phase than we've tried so far might be
802 // appropriate.
803 return NULL;
804 }
805
806 MetaWord* CollectorPolicy::satisfy_failed_metadata_allocation(
807 ClassLoaderData* loader_data,
808 size_t word_size,
809 Metaspace::MetadataType mdtype) {
810 uint loop_count = 0;
811 uint gc_count = 0;
812 uint full_gc_count = 0;
813
814 assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");
815
816 do {
817 MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
818 if (result != NULL) {
819 return result;
820 }
821
822 if (GCLocker::is_active_and_needs_gc()) {
823 // If the GCLocker is active, just expand and allocate.
824 // If that does not succeed, wait if this thread is not
825 // in a critical section itself.
826 result =
827 loader_data->metaspace_non_null()->expand_and_allocate(word_size,
828 mdtype);
829 if (result != NULL) {
830 return result;
831 }
832 JavaThread* jthr = JavaThread::current();
833 if (!jthr->in_critical()) {
834 // Wait for JNI critical section to be exited
835 GCLocker::stall_until_clear();
836 // The GC invoked by the last thread leaving the critical
837 // section will be a young collection and a full collection
838 // is (currently) needed for unloading classes so continue
839 // to the next iteration to get a full GC.
840 continue;
841 } else {
842 if (CheckJNICalls) {
843 fatal("Possible deadlock due to allocating while"
844 " in jni critical section");
845 }
846 return NULL;
847 }
848 }
849
850 { // Need lock to get self consistent gc_count's
851 MutexLocker ml(Heap_lock);
852 gc_count = Universe::heap()->total_collections();
853 full_gc_count = Universe::heap()->total_full_collections();
854 }
855
856 // Generate a VM operation
857 VM_CollectForMetadataAllocation op(loader_data,
858 word_size,
859 mdtype,
860 gc_count,
861 full_gc_count,
862 GCCause::_metadata_GC_threshold);
863 VMThread::execute(&op);
864
865 // If GC was locked out, try again. Check before checking success because the
866 // prologue could have succeeded and the GC still have been locked out.
867 if (op.gc_locked()) {
868 continue;
869 }
870
871 if (op.prologue_succeeded()) {
872 return op.result();
873 }
874 loop_count++;
875 if ((QueuedAllocationWarningCount > 0) &&
876 (loop_count % QueuedAllocationWarningCount == 0)) {
877 log_warning(gc, ergo)("satisfy_failed_metadata_allocation() retries %d times,"
878 " size=" SIZE_FORMAT, loop_count, word_size);
879 }
880 } while (true); // Until a GC is done
881 }
882
883 // Return true if any of the following is true:
884 // . the allocation won't fit into the current young gen heap
885 // . gc locker is occupied (jni critical section)
886 // . heap memory is tight -- the most recent previous collection
887 // was a full collection because a partial collection (would
888 // have) failed and is likely to fail again
889 bool GenCollectorPolicy::should_try_older_generation_allocation(
890 size_t word_size) const {
891 GenCollectedHeap* gch = GenCollectedHeap::heap();
892 size_t young_capacity = gch->young_gen()->capacity_before_gc();
893 return (word_size > heap_word_size(young_capacity))
894 || GCLocker::is_active_and_needs_gc()
895 || gch->incremental_collection_failed();
896 }
897
898
899 //
900 // MarkSweepPolicy methods
901 //
902
903 void MarkSweepPolicy::initialize_alignments() {
904 _space_alignment = _gen_alignment = (size_t)Generation::GenGrain;
905 _heap_alignment = compute_heap_alignment();
906 }
907
908 void MarkSweepPolicy::initialize_generations() {
909 _young_gen_spec = new GenerationSpec(Generation::DefNew, _initial_young_size, _max_young_size, _gen_alignment);
910 _old_gen_spec = new GenerationSpec(Generation::MarkSweepCompact, _initial_old_size, _max_old_size, _gen_alignment);
911 }
912
913 void MarkSweepPolicy::initialize_gc_policy_counters() {
914 // Initialize the policy counters - 2 collectors, 3 generations.
915 _gc_policy_counters = new GCPolicyCounters("Copy:MSC", 2, 3);
916 }
917