1 /*
2 * Copyright (c) 2011, 2024, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2017, 2021 SAP SE. All rights reserved.
4 * Copyright (c) 2023, 2024, Red Hat, Inc. All rights reserved.
5 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
6 *
7 * This code is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License version 2 only, as
9 * published by the Free Software Foundation.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 *
25 */
26
27 #include "precompiled.hpp"
28 #include "cds/cdsConfig.hpp"
29 #include "cds/metaspaceShared.hpp"
30 #include "classfile/classLoaderData.hpp"
31 #include "gc/shared/collectedHeap.hpp"
32 #include "logging/log.hpp"
33 #include "logging/logStream.hpp"
34 #include "memory/classLoaderMetaspace.hpp"
35 #include "memory/metaspace.hpp"
36 #include "memory/metaspace/chunkHeaderPool.hpp"
37 #include "memory/metaspace/chunkManager.hpp"
38 #include "memory/metaspace/commitLimiter.hpp"
39 #include "memory/metaspace/internalStats.hpp"
40 #include "memory/metaspace/metaspaceCommon.hpp"
41 #include "memory/metaspace/metaspaceContext.hpp"
42 #include "memory/metaspace/metaspaceReporter.hpp"
43 #include "memory/metaspace/metaspaceSettings.hpp"
44 #include "memory/metaspace/runningCounters.hpp"
45 #include "memory/metaspace/virtualSpaceList.hpp"
46 #include "memory/metaspaceCriticalAllocation.hpp"
47 #include "memory/metaspaceStats.hpp"
48 #include "memory/metaspaceTracer.hpp"
49 #include "memory/metaspaceUtils.hpp"
50 #include "memory/resourceArea.hpp"
51 #include "memory/universe.hpp"
52 #include "nmt/memTracker.hpp"
53 #include "oops/compressedKlass.inline.hpp"
54 #include "oops/compressedOops.hpp"
55 #include "prims/jvmtiExport.hpp"
56 #include "runtime/atomic.hpp"
57 #include "runtime/globals_extension.hpp"
58 #include "runtime/init.hpp"
59 #include "runtime/java.hpp"
60 #include "utilities/copy.hpp"
61 #include "utilities/debug.hpp"
62 #include "utilities/formatBuffer.hpp"
63 #include "utilities/globalDefinitions.hpp"
64 #include "virtualspace.hpp"
65
66 using metaspace::ChunkManager;
67 using metaspace::CommitLimiter;
68 using metaspace::MetaspaceContext;
69 using metaspace::MetaspaceReporter;
70 using metaspace::RunningCounters;
71 using metaspace::VirtualSpaceList;
72
73 size_t MetaspaceUtils::used_words() {
74 return RunningCounters::used_words();
75 }
76
77 size_t MetaspaceUtils::used_words(Metaspace::MetadataType mdtype) {
78 return mdtype == Metaspace::ClassType ? RunningCounters::used_words_class() : RunningCounters::used_words_nonclass();
79 }
80
81 size_t MetaspaceUtils::reserved_words() {
82 return RunningCounters::reserved_words();
83 }
84
85 size_t MetaspaceUtils::reserved_words(Metaspace::MetadataType mdtype) {
86 return mdtype == Metaspace::ClassType ? RunningCounters::reserved_words_class() : RunningCounters::reserved_words_nonclass();
87 }
88
89 size_t MetaspaceUtils::committed_words() {
90 return RunningCounters::committed_words();
91 }
92
93 size_t MetaspaceUtils::committed_words(Metaspace::MetadataType mdtype) {
94 return mdtype == Metaspace::ClassType ? RunningCounters::committed_words_class() : RunningCounters::committed_words_nonclass();
95 }
96
97 // Helper for get_statistics()
98 static void get_values_for(Metaspace::MetadataType mdtype, size_t* reserved, size_t* committed, size_t* used) {
99 #define w2b(x) (x * sizeof(MetaWord))
100 if (mdtype == Metaspace::ClassType) {
101 *reserved = w2b(RunningCounters::reserved_words_class());
102 *committed = w2b(RunningCounters::committed_words_class());
103 *used = w2b(RunningCounters::used_words_class());
104 } else {
105 *reserved = w2b(RunningCounters::reserved_words_nonclass());
106 *committed = w2b(RunningCounters::committed_words_nonclass());
107 *used = w2b(RunningCounters::used_words_nonclass());
108 }
109 #undef w2b
110 }
111
112 // Retrieve all statistics in one go; make sure the values are consistent.
113 MetaspaceStats MetaspaceUtils::get_statistics(Metaspace::MetadataType mdtype) {
114
115 // Consistency:
116 // This function reads three values (reserved, committed, used) from different counters. These counters
117 // may (very rarely) be out of sync. This has been a source for intermittent test errors in the past
118 // (see e.g. JDK-8237872, JDK-8151460).
119 // - reserved and committed counter are updated under protection of Metaspace_lock; an inconsistency
120 // between them can be the result of a dirty read.
121 // - used is an atomic counter updated outside any lock range; there is no way to guarantee
122 // a clean read wrt the other two values.
123 // Reading these values under lock protection would would only help for the first case. Therefore
124 // we don't bother and just re-read several times, then give up and correct the values.
125
126 size_t r = 0, c = 0, u = 0; // Note: byte values.
127 get_values_for(mdtype, &r, &c, &u);
128 int retries = 10;
129 // If the first retrieval resulted in inconsistent values, retry a bit...
130 while ((r < c || c < u) && --retries >= 0) {
131 get_values_for(mdtype, &r, &c, &u);
132 }
133 if (c < u || r < c) { // still inconsistent.
134 // ... but not endlessly. If we don't get consistent values, correct them on the fly.
135 // The logic here is that we trust the used counter - its an atomic counter and whatever we see
136 // must have been the truth once - and from that we reconstruct a likely set of committed/reserved
137 // values.
138 metaspace::InternalStats::inc_num_inconsistent_stats();
139 if (c < u) {
140 c = align_up(u, Metaspace::commit_alignment());
141 }
142 if (r < c) {
143 r = align_up(c, Metaspace::reserve_alignment());
144 }
145 }
146 return MetaspaceStats(r, c, u);
147 }
148
149 MetaspaceCombinedStats MetaspaceUtils::get_combined_statistics() {
150 return MetaspaceCombinedStats(get_statistics(Metaspace::ClassType), get_statistics(Metaspace::NonClassType));
151 }
152
153 void MetaspaceUtils::print_metaspace_change(const MetaspaceCombinedStats& pre_meta_values) {
154 // Get values now:
155 const MetaspaceCombinedStats meta_values = get_combined_statistics();
156
157 // We print used and committed since these are the most useful at-a-glance vitals for Metaspace:
158 // - used tells you how much memory is actually used for metadata
159 // - committed tells you how much memory is committed for the purpose of metadata
160 // The difference between those two would be waste, which can have various forms (freelists,
161 // unused parts of committed chunks etc)
162 //
163 // Left out is reserved, since this is not as exciting as the first two values: for class space,
164 // it is a constant (to uninformed users, often confusingly large). For non-class space, it would
165 // be interesting since free chunks can be uncommitted, but for now it is left out.
166
167 if (Metaspace::using_class_space()) {
168 log_info(gc, metaspace)(HEAP_CHANGE_FORMAT" "
169 HEAP_CHANGE_FORMAT" "
170 HEAP_CHANGE_FORMAT,
171 HEAP_CHANGE_FORMAT_ARGS("Metaspace",
172 pre_meta_values.used(),
173 pre_meta_values.committed(),
174 meta_values.used(),
175 meta_values.committed()),
176 HEAP_CHANGE_FORMAT_ARGS("NonClass",
177 pre_meta_values.non_class_used(),
178 pre_meta_values.non_class_committed(),
179 meta_values.non_class_used(),
180 meta_values.non_class_committed()),
181 HEAP_CHANGE_FORMAT_ARGS("Class",
182 pre_meta_values.class_used(),
183 pre_meta_values.class_committed(),
184 meta_values.class_used(),
185 meta_values.class_committed()));
186 } else {
187 log_info(gc, metaspace)(HEAP_CHANGE_FORMAT,
188 HEAP_CHANGE_FORMAT_ARGS("Metaspace",
189 pre_meta_values.used(),
190 pre_meta_values.committed(),
191 meta_values.used(),
192 meta_values.committed()));
193 }
194 }
195
196 // This will print out a basic metaspace usage report but
197 // unlike print_report() is guaranteed not to lock or to walk the CLDG.
198 void MetaspaceUtils::print_basic_report(outputStream* out, size_t scale) {
199 MetaspaceReporter::print_basic_report(out, scale);
200 }
201
202 // Prints a report about the current metaspace state.
203 // Optional parts can be enabled via flags.
204 // Function will walk the CLDG and will lock the expand lock; if that is not
205 // convenient, use print_basic_report() instead.
206 void MetaspaceUtils::print_report(outputStream* out, size_t scale) {
207 const int flags =
208 (int)MetaspaceReporter::Option::ShowLoaders |
209 (int)MetaspaceReporter::Option::BreakDownByChunkType |
210 (int)MetaspaceReporter::Option::ShowClasses;
211 MetaspaceReporter::print_report(out, scale, flags);
212 }
213
214 void MetaspaceUtils::print_on(outputStream* out) {
215
216 // Used from all GCs. It first prints out totals, then, separately, the class space portion.
217 MetaspaceCombinedStats stats = get_combined_statistics();
218 out->print_cr(" Metaspace "
219 "used " SIZE_FORMAT "K, "
220 "committed " SIZE_FORMAT "K, "
221 "reserved " SIZE_FORMAT "K",
222 stats.used()/K,
223 stats.committed()/K,
224 stats.reserved()/K);
225
226 if (Metaspace::using_class_space()) {
227 out->print_cr(" class space "
228 "used " SIZE_FORMAT "K, "
229 "committed " SIZE_FORMAT "K, "
230 "reserved " SIZE_FORMAT "K",
231 stats.class_space_stats().used()/K,
232 stats.class_space_stats().committed()/K,
233 stats.class_space_stats().reserved()/K);
234 }
235 }
236
237 #ifdef ASSERT
238 void MetaspaceUtils::verify() {
239 if (Metaspace::initialized()) {
240
241 // Verify non-class chunkmanager...
242 ChunkManager* cm = ChunkManager::chunkmanager_nonclass();
243 cm->verify();
244
245 // ... and space list.
246 VirtualSpaceList* vsl = VirtualSpaceList::vslist_nonclass();
247 vsl->verify();
248
249 if (Metaspace::using_class_space()) {
250 // If we use compressed class pointers, verify class chunkmanager...
251 cm = ChunkManager::chunkmanager_class();
252 cm->verify();
253
254 // ... and class spacelist.
255 vsl = VirtualSpaceList::vslist_class();
256 vsl->verify();
257 }
258
259 }
260 }
261 #endif
262
263 ////////////////////////////////7
264 // MetaspaceGC methods
265
266 volatile size_t MetaspaceGC::_capacity_until_GC = 0;
267 uint MetaspaceGC::_shrink_factor = 0;
268
269 // VM_CollectForMetadataAllocation is the vm operation used to GC.
270 // Within the VM operation after the GC the attempt to allocate the metadata
271 // should succeed. If the GC did not free enough space for the metaspace
272 // allocation, the HWM is increased so that another virtualspace will be
273 // allocated for the metadata. With perm gen the increase in the perm
274 // gen had bounds, MinMetaspaceExpansion and MaxMetaspaceExpansion. The
275 // metaspace policy uses those as the small and large steps for the HWM.
276 //
277 // After the GC the compute_new_size() for MetaspaceGC is called to
278 // resize the capacity of the metaspaces. The current implementation
279 // is based on the flags MinMetaspaceFreeRatio and MaxMetaspaceFreeRatio used
280 // to resize the Java heap by some GC's. New flags can be implemented
281 // if really needed. MinMetaspaceFreeRatio is used to calculate how much
282 // free space is desirable in the metaspace capacity to decide how much
283 // to increase the HWM. MaxMetaspaceFreeRatio is used to decide how much
284 // free space is desirable in the metaspace capacity before decreasing
285 // the HWM.
286
287 // Calculate the amount to increase the high water mark (HWM).
288 // Increase by a minimum amount (MinMetaspaceExpansion) so that
289 // another expansion is not requested too soon. If that is not
290 // enough to satisfy the allocation, increase by MaxMetaspaceExpansion.
291 // If that is still not enough, expand by the size of the allocation
292 // plus some.
293 size_t MetaspaceGC::delta_capacity_until_GC(size_t bytes) {
294 size_t min_delta = MinMetaspaceExpansion;
295 size_t max_delta = MaxMetaspaceExpansion;
296 size_t delta = align_up(bytes, Metaspace::commit_alignment());
297
298 if (delta <= min_delta) {
299 delta = min_delta;
300 } else if (delta <= max_delta) {
301 // Don't want to hit the high water mark on the next
302 // allocation so make the delta greater than just enough
303 // for this allocation.
304 delta = max_delta;
305 } else {
306 // This allocation is large but the next ones are probably not
307 // so increase by the minimum.
308 delta = delta + min_delta;
309 }
310
311 assert_is_aligned(delta, Metaspace::commit_alignment());
312
313 return delta;
314 }
315
316 size_t MetaspaceGC::capacity_until_GC() {
317 size_t value = Atomic::load_acquire(&_capacity_until_GC);
318 assert(value >= MetaspaceSize, "Not initialized properly?");
319 return value;
320 }
321
322 // Try to increase the _capacity_until_GC limit counter by v bytes.
323 // Returns true if it succeeded. It may fail if either another thread
324 // concurrently increased the limit or the new limit would be larger
325 // than MaxMetaspaceSize.
326 // On success, optionally returns new and old metaspace capacity in
327 // new_cap_until_GC and old_cap_until_GC respectively.
328 // On error, optionally sets can_retry to indicate whether if there is
329 // actually enough space remaining to satisfy the request.
330 bool MetaspaceGC::inc_capacity_until_GC(size_t v, size_t* new_cap_until_GC, size_t* old_cap_until_GC, bool* can_retry) {
331 assert_is_aligned(v, Metaspace::commit_alignment());
332
333 size_t old_capacity_until_GC = _capacity_until_GC;
334 size_t new_value = old_capacity_until_GC + v;
335
336 if (new_value < old_capacity_until_GC) {
337 // The addition wrapped around, set new_value to aligned max value.
338 new_value = align_down(max_uintx, Metaspace::reserve_alignment());
339 }
340
341 if (new_value > MaxMetaspaceSize) {
342 if (can_retry != nullptr) {
343 *can_retry = false;
344 }
345 return false;
346 }
347
348 if (can_retry != nullptr) {
349 *can_retry = true;
350 }
351 size_t prev_value = Atomic::cmpxchg(&_capacity_until_GC, old_capacity_until_GC, new_value);
352
353 if (old_capacity_until_GC != prev_value) {
354 return false;
355 }
356
357 if (new_cap_until_GC != nullptr) {
358 *new_cap_until_GC = new_value;
359 }
360 if (old_cap_until_GC != nullptr) {
361 *old_cap_until_GC = old_capacity_until_GC;
362 }
363 return true;
364 }
365
366 size_t MetaspaceGC::dec_capacity_until_GC(size_t v) {
367 assert_is_aligned(v, Metaspace::commit_alignment());
368
369 return Atomic::sub(&_capacity_until_GC, v);
370 }
371
372 void MetaspaceGC::initialize() {
373 // Set the high-water mark to MaxMetapaceSize during VM initializaton since
374 // we can't do a GC during initialization.
375 _capacity_until_GC = MaxMetaspaceSize;
376 }
377
378 void MetaspaceGC::post_initialize() {
379 // Reset the high-water mark once the VM initialization is done.
380 _capacity_until_GC = MAX2(MetaspaceUtils::committed_bytes(), MetaspaceSize);
381 }
382
383 bool MetaspaceGC::can_expand(size_t word_size, bool is_class) {
384 // Check if the compressed class space is full.
385 if (is_class && Metaspace::using_class_space()) {
386 size_t class_committed = MetaspaceUtils::committed_bytes(Metaspace::ClassType);
387 if (class_committed + word_size * BytesPerWord > CompressedClassSpaceSize) {
388 log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by " SIZE_FORMAT " words (CompressedClassSpaceSize = " SIZE_FORMAT " words)",
389 (is_class ? "class" : "non-class"), word_size, CompressedClassSpaceSize / sizeof(MetaWord));
390 return false;
391 }
392 }
393
394 // Check if the user has imposed a limit on the metaspace memory.
395 size_t committed_bytes = MetaspaceUtils::committed_bytes();
396 if (committed_bytes + word_size * BytesPerWord > MaxMetaspaceSize) {
397 log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by " SIZE_FORMAT " words (MaxMetaspaceSize = " SIZE_FORMAT " words)",
398 (is_class ? "class" : "non-class"), word_size, MaxMetaspaceSize / sizeof(MetaWord));
399 return false;
400 }
401
402 return true;
403 }
404
405 size_t MetaspaceGC::allowed_expansion() {
406 size_t committed_bytes = MetaspaceUtils::committed_bytes();
407 size_t capacity_until_gc = capacity_until_GC();
408
409 size_t left_until_max = MaxMetaspaceSize - committed_bytes;
410 // capacity_until_GC may have been decreased concurrently and may
411 // temporarily be lower than what metaspace has committed. Allow for that.
412 size_t left_until_GC = capacity_until_gc > committed_bytes ?
413 capacity_until_gc - committed_bytes : 0;
414 size_t left_to_commit = MIN2(left_until_GC, left_until_max);
415 log_trace(gc, metaspace, freelist)("allowed expansion words: " SIZE_FORMAT
416 " (left_until_max: " SIZE_FORMAT ", left_until_GC: " SIZE_FORMAT ".",
417 left_to_commit / BytesPerWord, left_until_max / BytesPerWord, left_until_GC / BytesPerWord);
418
419 return left_to_commit / BytesPerWord;
420 }
421
422 void MetaspaceGC::compute_new_size() {
423 assert(_shrink_factor <= 100, "invalid shrink factor");
424 uint current_shrink_factor = _shrink_factor;
425 _shrink_factor = 0;
426
427 // Using committed_bytes() for used_after_gc is an overestimation, since the
428 // chunk free lists are included in committed_bytes() and the memory in an
429 // un-fragmented chunk free list is available for future allocations.
430 // However, if the chunk free lists becomes fragmented, then the memory may
431 // not be available for future allocations and the memory is therefore "in use".
432 // Including the chunk free lists in the definition of "in use" is therefore
433 // necessary. Not including the chunk free lists can cause capacity_until_GC to
434 // shrink below committed_bytes() and this has caused serious bugs in the past.
435 const double used_after_gc = (double)MetaspaceUtils::committed_bytes();
436 const size_t capacity_until_GC = MetaspaceGC::capacity_until_GC();
437
438 const double minimum_free_percentage = MinMetaspaceFreeRatio / 100.0;
439 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
440
441 const double min_tmp = used_after_gc / maximum_used_percentage;
442 size_t minimum_desired_capacity =
443 (size_t)MIN2(min_tmp, double(MaxMetaspaceSize));
444 // Don't shrink less than the initial generation size
445 minimum_desired_capacity = MAX2(minimum_desired_capacity,
446 MetaspaceSize);
447
448 log_trace(gc, metaspace)("MetaspaceGC::compute_new_size: ");
449 log_trace(gc, metaspace)(" minimum_free_percentage: %6.2f maximum_used_percentage: %6.2f",
450 minimum_free_percentage, maximum_used_percentage);
451 log_trace(gc, metaspace)(" used_after_gc : %6.1fKB", used_after_gc / (double) K);
452
453 size_t shrink_bytes = 0;
454 if (capacity_until_GC < minimum_desired_capacity) {
455 // If we have less capacity below the metaspace HWM, then
456 // increment the HWM.
457 size_t expand_bytes = minimum_desired_capacity - capacity_until_GC;
458 expand_bytes = align_up(expand_bytes, Metaspace::commit_alignment());
459 // Don't expand unless it's significant
460 if (expand_bytes >= MinMetaspaceExpansion) {
461 size_t new_capacity_until_GC = 0;
462 bool succeeded = MetaspaceGC::inc_capacity_until_GC(expand_bytes, &new_capacity_until_GC);
463 assert(succeeded, "Should always successfully increment HWM when at safepoint");
464
465 Metaspace::tracer()->report_gc_threshold(capacity_until_GC,
466 new_capacity_until_GC,
467 MetaspaceGCThresholdUpdater::ComputeNewSize);
468 log_trace(gc, metaspace)(" expanding: minimum_desired_capacity: %6.1fKB expand_bytes: %6.1fKB MinMetaspaceExpansion: %6.1fKB new metaspace HWM: %6.1fKB",
469 (double) minimum_desired_capacity / (double) K,
470 (double) expand_bytes / (double) K,
471 (double) MinMetaspaceExpansion / (double) K,
472 (double) new_capacity_until_GC / (double) K);
473 }
474 return;
475 }
476
477 // No expansion, now see if we want to shrink
478 // We would never want to shrink more than this
479 assert(capacity_until_GC >= minimum_desired_capacity,
480 SIZE_FORMAT " >= " SIZE_FORMAT,
481 capacity_until_GC, minimum_desired_capacity);
482 size_t max_shrink_bytes = capacity_until_GC - minimum_desired_capacity;
483
484 // Should shrinking be considered?
485 if (MaxMetaspaceFreeRatio < 100) {
486 const double maximum_free_percentage = MaxMetaspaceFreeRatio / 100.0;
487 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
488 const double max_tmp = used_after_gc / minimum_used_percentage;
489 size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(MaxMetaspaceSize));
490 maximum_desired_capacity = MAX2(maximum_desired_capacity,
491 MetaspaceSize);
492 log_trace(gc, metaspace)(" maximum_free_percentage: %6.2f minimum_used_percentage: %6.2f",
493 maximum_free_percentage, minimum_used_percentage);
494 log_trace(gc, metaspace)(" minimum_desired_capacity: %6.1fKB maximum_desired_capacity: %6.1fKB",
495 (double) minimum_desired_capacity / (double) K, (double) maximum_desired_capacity / (double) K);
496
497 assert(minimum_desired_capacity <= maximum_desired_capacity,
498 "sanity check");
499
500 if (capacity_until_GC > maximum_desired_capacity) {
501 // Capacity too large, compute shrinking size
502 shrink_bytes = capacity_until_GC - maximum_desired_capacity;
503 // We don't want shrink all the way back to initSize if people call
504 // System.gc(), because some programs do that between "phases" and then
505 // we'd just have to grow the heap up again for the next phase. So we
506 // damp the shrinking: 0% on the first call, 10% on the second call, 40%
507 // on the third call, and 100% by the fourth call. But if we recompute
508 // size without shrinking, it goes back to 0%.
509 shrink_bytes = shrink_bytes / 100 * current_shrink_factor;
510
511 shrink_bytes = align_down(shrink_bytes, Metaspace::commit_alignment());
512
513 assert(shrink_bytes <= max_shrink_bytes,
514 "invalid shrink size " SIZE_FORMAT " not <= " SIZE_FORMAT,
515 shrink_bytes, max_shrink_bytes);
516 if (current_shrink_factor == 0) {
517 _shrink_factor = 10;
518 } else {
519 _shrink_factor = MIN2(current_shrink_factor * 4, (uint) 100);
520 }
521 log_trace(gc, metaspace)(" shrinking: initThreshold: %.1fK maximum_desired_capacity: %.1fK",
522 (double) MetaspaceSize / (double) K, (double) maximum_desired_capacity / (double) K);
523 log_trace(gc, metaspace)(" shrink_bytes: %.1fK current_shrink_factor: %d new shrink factor: %d MinMetaspaceExpansion: %.1fK",
524 (double) shrink_bytes / (double) K, current_shrink_factor, _shrink_factor, (double) MinMetaspaceExpansion / (double) K);
525 }
526 }
527
528 // Don't shrink unless it's significant
529 if (shrink_bytes >= MinMetaspaceExpansion &&
530 ((capacity_until_GC - shrink_bytes) >= MetaspaceSize)) {
531 size_t new_capacity_until_GC = MetaspaceGC::dec_capacity_until_GC(shrink_bytes);
532 Metaspace::tracer()->report_gc_threshold(capacity_until_GC,
533 new_capacity_until_GC,
534 MetaspaceGCThresholdUpdater::ComputeNewSize);
535 }
536 }
537
538 ////// Metaspace methods /////
539
540 const MetaspaceTracer* Metaspace::_tracer = nullptr;
541 const void* Metaspace::_class_space_start = nullptr;
542 const void* Metaspace::_class_space_end = nullptr;
543
544 bool Metaspace::initialized() {
545 return metaspace::MetaspaceContext::context_nonclass() != nullptr
546 LP64_ONLY(&& (using_class_space() ? Metaspace::class_space_is_initialized() : true));
547 }
548
549 #ifdef _LP64
550
551 void Metaspace::print_compressed_class_space(outputStream* st) {
552 if (VirtualSpaceList::vslist_class() != nullptr) {
553 MetaWord* base = VirtualSpaceList::vslist_class()->base_of_first_node();
554 size_t size = VirtualSpaceList::vslist_class()->word_size_of_first_node();
555 MetaWord* top = base + size;
556 st->print("Compressed class space mapped at: " PTR_FORMAT "-" PTR_FORMAT ", reserved size: " SIZE_FORMAT,
557 p2i(base), p2i(top), (top - base) * BytesPerWord);
558 st->cr();
559 }
560 }
561
562 // Given a prereserved space, use that to set up the compressed class space list.
563 void Metaspace::initialize_class_space(ReservedSpace rs) {
564 assert(rs.size() >= CompressedClassSpaceSize,
565 SIZE_FORMAT " != " SIZE_FORMAT, rs.size(), CompressedClassSpaceSize);
566 assert(using_class_space(), "Must be using class space");
567
568 assert(rs.size() == CompressedClassSpaceSize, SIZE_FORMAT " != " SIZE_FORMAT,
569 rs.size(), CompressedClassSpaceSize);
570 assert(is_aligned(rs.base(), Metaspace::reserve_alignment()) &&
571 is_aligned(rs.size(), Metaspace::reserve_alignment()),
572 "wrong alignment");
573
574 MetaspaceContext::initialize_class_space_context(rs);
575 _class_space_start = rs.base();
576 _class_space_end = rs.end();
577 }
578
579 // Returns true if class space has been setup (initialize_class_space).
580 bool Metaspace::class_space_is_initialized() {
581 return MetaspaceContext::context_class() != nullptr;
582 }
583
584 // Reserve a range of memory that is to contain narrow Klass IDs. If "try_in_low_address_ranges"
585 // is true, we will attempt to reserve memory suitable for zero-based encoding.
586 ReservedSpace Metaspace::reserve_address_space_for_compressed_classes(size_t size, bool optimize_for_zero_base) {
587 char* result = nullptr;
588
589 NOT_ZERO(result =
590 (char*) CompressedKlassPointers::reserve_address_space_for_compressed_classes(size, RandomizeClassSpaceLocation,
591 optimize_for_zero_base));
592
593 if (result == nullptr) {
594 // Fallback: reserve anywhere
595 log_debug(metaspace, map)("Trying anywhere...");
596 result = os::reserve_memory_aligned(size, Metaspace::reserve_alignment(), false);
597 }
598
599 // Wrap resulting range in ReservedSpace
600 ReservedSpace rs;
601 if (result != nullptr) {
602 log_debug(metaspace, map)("Mapped at " PTR_FORMAT, p2i(result));
603 assert(is_aligned(result, Metaspace::reserve_alignment()), "Alignment too small for metaspace");
604 rs = ReservedSpace::space_for_range(result, size, Metaspace::reserve_alignment(),
605 os::vm_page_size(), false, false);
606 } else {
607 log_debug(metaspace, map)("Failed to map.");
608 rs = ReservedSpace();
609 }
610 return rs;
611 }
612 #endif // _LP64
613
614 size_t Metaspace::reserve_alignment_words() {
615 return metaspace::Settings::virtual_space_node_reserve_alignment_words();
616 }
617
618 size_t Metaspace::commit_alignment_words() {
619 return metaspace::Settings::commit_granule_words();
620 }
621
622 void Metaspace::ergo_initialize() {
623
624 // Must happen before using any setting from Settings::---
625 metaspace::Settings::ergo_initialize();
626
627 // MaxMetaspaceSize and CompressedClassSpaceSize:
628 //
629 // MaxMetaspaceSize is the maximum size, in bytes, of memory we are allowed
630 // to commit for the Metaspace.
631 // It is just a number; a limit we compare against before committing. It
632 // does not have to be aligned to anything.
633 // It gets used as compare value before attempting to increase the metaspace
634 // commit charge. It defaults to max_uintx (unlimited).
635 //
636 // CompressedClassSpaceSize is the size, in bytes, of the address range we
637 // pre-reserve for the compressed class space (if we use class space).
638 // This size has to be aligned to the metaspace reserve alignment (to the
639 // size of a root chunk). It gets aligned up from whatever value the caller
640 // gave us to the next multiple of root chunk size.
641 //
642 // Note: Strictly speaking MaxMetaspaceSize and CompressedClassSpaceSize have
643 // very little to do with each other. The notion often encountered:
644 // MaxMetaspaceSize = CompressedClassSpaceSize + <non-class metadata size>
645 // is subtly wrong: MaxMetaspaceSize can besmaller than CompressedClassSpaceSize,
646 // in which case we just would not be able to fully commit the class space range.
647 //
648 // We still adjust CompressedClassSpaceSize to reasonable limits, mainly to
649 // save on reserved space, and to make ergnonomics less confusing.
650
651 MaxMetaspaceSize = MAX2(MaxMetaspaceSize, commit_alignment());
652
653 if (UseCompressedClassPointers) {
654 // Adjust size of the compressed class space.
655
656 const size_t res_align = reserve_alignment();
657
658 // Let CCS size not be larger than 80% of MaxMetaspaceSize. Note that is
659 // grossly over-dimensioned for most usage scenarios; typical ratio of
660 // class space : non class space usage is about 1:6. With many small classes,
661 // it can get as low as 1:2. It is not a big deal though since ccs is only
662 // reserved and will be committed on demand only.
663 const size_t max_ccs_size = 8 * (MaxMetaspaceSize / 10);
664
665 // CCS is also limited by the max. possible Klass encoding range size
666 const size_t max_encoding_range = CompressedKlassPointers::max_encoding_range_size();
667 assert(max_encoding_range >= res_align,
668 "Encoding range (%zu) must cover at least a full root chunk (%zu)",
669 max_encoding_range, res_align);
670
671 size_t adjusted_ccs_size = MIN3(CompressedClassSpaceSize, max_ccs_size, max_encoding_range);
672
673 // CCS must be aligned to root chunk size, and be at least the size of one
674 // root chunk. But impose a miminum size of 1 root chunk (16MB).
675 adjusted_ccs_size = MAX2(align_down(adjusted_ccs_size, res_align), res_align);
676
677 // Print a warning if the adjusted size differs from the users input
678 if (CompressedClassSpaceSize != adjusted_ccs_size) {
679 #define X "CompressedClassSpaceSize adjusted from user input " \
680 "%zu bytes to %zu bytes", CompressedClassSpaceSize, adjusted_ccs_size
681 if (FLAG_IS_CMDLINE(CompressedClassSpaceSize)) {
682 log_warning(metaspace)(X);
683 } else {
684 log_info(metaspace)(X);
685 }
686 #undef X
687 }
688
689 // Note: re-adjusting may have us left with a CompressedClassSpaceSize
690 // larger than MaxMetaspaceSize for very small values of MaxMetaspaceSize.
691 // Lets just live with that, its not a big deal.
692 if (adjusted_ccs_size != CompressedClassSpaceSize) {
693 FLAG_SET_ERGO(CompressedClassSpaceSize, adjusted_ccs_size);
694 log_info(metaspace)("Setting CompressedClassSpaceSize to " SIZE_FORMAT ".",
695 CompressedClassSpaceSize);
696 }
697 }
698
699 // Set MetaspaceSize, MinMetaspaceExpansion and MaxMetaspaceExpansion
700 if (MetaspaceSize > MaxMetaspaceSize) {
701 MetaspaceSize = MaxMetaspaceSize;
702 }
703
704 MetaspaceSize = align_down_bounded(MetaspaceSize, commit_alignment());
705
706 assert(MetaspaceSize <= MaxMetaspaceSize, "MetaspaceSize should be limited by MaxMetaspaceSize");
707
708 MinMetaspaceExpansion = align_down_bounded(MinMetaspaceExpansion, commit_alignment());
709 MaxMetaspaceExpansion = align_down_bounded(MaxMetaspaceExpansion, commit_alignment());
710
711 }
712
713 void Metaspace::global_initialize() {
714 MetaspaceGC::initialize(); // <- since we do not prealloc init chunks anymore is this still needed?
715
716 metaspace::ChunkHeaderPool::initialize();
717
718 if (CDSConfig::is_dumping_static_archive()) {
719 assert(!CDSConfig::is_using_archive(), "sanity");
720 MetaspaceShared::initialize_for_static_dump();
721 }
722
723 // If UseCompressedClassPointers=1, we have two cases:
724 // a) if CDS is active (runtime, Xshare=on), it will create the class space
725 // for us, initialize it and set up CompressedKlassPointers encoding.
726 // Class space will be reserved above the mapped archives.
727 // b) if CDS either deactivated (Xshare=off) or a static dump is to be done (Xshare:dump),
728 // we will create the class space on our own. It will be placed above the java heap,
729 // since we assume it has been placed in low
730 // address regions. We may rethink this (see JDK-8244943). Failing that,
731 // it will be placed anywhere.
732
733 #if INCLUDE_CDS
734 // case (a)
735 if (CDSConfig::is_using_archive()) {
736 if (!FLAG_IS_DEFAULT(CompressedClassSpaceBaseAddress)) {
737 log_warning(metaspace)("CDS active - ignoring CompressedClassSpaceBaseAddress.");
738 }
739 MetaspaceShared::initialize_runtime_shared_and_meta_spaces();
740 // If any of the archived space fails to map, UseSharedSpaces
741 // is reset to false.
742 }
743 #endif // INCLUDE_CDS
744
745 #ifdef _LP64
746
747 if (using_class_space() && !class_space_is_initialized()) {
748 assert(!CDSConfig::is_using_archive(), "CDS archive is not mapped at this point");
749
750 // case (b) (No CDS)
751 ReservedSpace rs;
752 const size_t size = align_up(CompressedClassSpaceSize, Metaspace::reserve_alignment());
753
754 // If CompressedClassSpaceBaseAddress is set, we attempt to force-map class space to
755 // the given address. This is a debug-only feature aiding tests. Due to the ASLR lottery
756 // this may fail, in which case the VM will exit after printing an appropriate message.
757 // Tests using this switch should cope with that.
758 if (CompressedClassSpaceBaseAddress != 0) {
759 const address base = (address)CompressedClassSpaceBaseAddress;
760 if (!is_aligned(base, Metaspace::reserve_alignment())) {
761 vm_exit_during_initialization(
762 err_msg("CompressedClassSpaceBaseAddress=" PTR_FORMAT " invalid "
763 "(must be aligned to " SIZE_FORMAT_X ").",
764 CompressedClassSpaceBaseAddress, Metaspace::reserve_alignment()));
765 }
766 rs = ReservedSpace(size, Metaspace::reserve_alignment(),
767 os::vm_page_size() /* large */, (char*)base);
768 if (rs.is_reserved()) {
769 log_info(metaspace)("Successfully forced class space address to " PTR_FORMAT, p2i(base));
770 } else {
771 LogTarget(Debug, metaspace) lt;
772 if (lt.is_enabled()) {
773 LogStream ls(lt);
774 os::print_memory_mappings((char*)base, size, &ls);
775 }
776 vm_exit_during_initialization(
777 err_msg("CompressedClassSpaceBaseAddress=" PTR_FORMAT " given, but reserving class space failed.",
778 CompressedClassSpaceBaseAddress));
779 }
780 }
781
782 // ...failing that, reserve anywhere, but let platform do optimized placement:
783 if (!rs.is_reserved()) {
784 log_info(metaspace)("Reserving compressed class space anywhere");
785 rs = Metaspace::reserve_address_space_for_compressed_classes(size, true);
786 }
787
788 // ...failing that, give up.
789 if (!rs.is_reserved()) {
790 vm_exit_during_initialization(
791 err_msg("Could not allocate compressed class space: " SIZE_FORMAT " bytes",
792 CompressedClassSpaceSize));
793 }
794
795 // Mark class space as such
796 MemTracker::record_virtual_memory_type((address)rs.base(), mtClass);
797
798 // Initialize space
799 Metaspace::initialize_class_space(rs);
800
801 // Set up compressed class pointer encoding.
802 // In CDS=off mode, we give the JVM some leeway to choose a favorable base/shift combination.
803 CompressedKlassPointers::initialize((address)rs.base(), rs.size());
804 }
805
806 #endif
807
808 // Initialize non-class virtual space list, and its chunk manager:
809 MetaspaceContext::initialize_nonclass_space_context();
810
811 _tracer = new MetaspaceTracer();
812
813 // We must prevent the very first address of the ccs from being used to store
814 // metadata, since that address would translate to a narrow pointer of 0, and the
815 // VM does not distinguish between "narrow 0 as in null" and "narrow 0 as in start
816 // of ccs".
817 // Before Elastic Metaspace that did not happen due to the fact that every Metachunk
818 // had a header and therefore could not allocate anything at offset 0.
819 #ifdef _LP64
820 if (using_class_space()) {
821 // The simplest way to fix this is to allocate a tiny dummy chunk right at the
822 // start of ccs and do not use it for anything.
823 MetaspaceContext::context_class()->cm()->get_chunk(metaspace::chunklevel::HIGHEST_CHUNK_LEVEL);
824 }
825 #endif
826
827 #ifdef _LP64
828 if (UseCompressedClassPointers) {
829 // Note: "cds" would be a better fit but keep this for backward compatibility.
830 LogTarget(Info, gc, metaspace) lt;
831 if (lt.is_enabled()) {
832 ResourceMark rm;
833 LogStream ls(lt);
834 CDS_ONLY(MetaspaceShared::print_on(&ls);)
835 Metaspace::print_compressed_class_space(&ls);
836 CompressedKlassPointers::print_mode(&ls);
837 }
838 }
839 #endif
840
841 }
842
843 void Metaspace::post_initialize() {
844 MetaspaceGC::post_initialize();
845 }
846
847 size_t Metaspace::max_allocation_word_size() {
848 return metaspace::chunklevel::MAX_CHUNK_WORD_SIZE;
849 }
850
851 // This version of Metaspace::allocate does not throw OOM but simply returns null, and
852 // is suitable for calling from non-Java threads.
853 // Callers are responsible for checking null.
854 MetaWord* Metaspace::allocate(ClassLoaderData* loader_data, size_t word_size,
855 MetaspaceObj::Type type) {
856 assert(word_size <= Metaspace::max_allocation_word_size(),
857 "allocation size too large (" SIZE_FORMAT ")", word_size);
858
859 assert(loader_data != nullptr, "Should never pass around a null loader_data. "
860 "ClassLoaderData::the_null_class_loader_data() should have been used.");
861
862 // Deal with concurrent unloading failed allocation starvation
863 MetaspaceCriticalAllocation::block_if_concurrent_purge();
864
865 MetadataType mdtype = (type == MetaspaceObj::ClassType) ? ClassType : NonClassType;
866
867 // Try to allocate metadata.
868 MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
869
870 if (result != nullptr) {
871 #ifdef ASSERT
872 if (using_class_space() && mdtype == ClassType) {
873 assert(is_in_class_space(result) &&
874 is_aligned(result, CompressedKlassPointers::klass_alignment_in_bytes()), "Sanity");
875 } else {
876 assert((is_in_class_space(result) || is_in_nonclass_metaspace(result)) &&
877 is_aligned(result, Metaspace::min_allocation_alignment_bytes), "Sanity");
878 }
879 #endif
880 // Zero initialize.
881 Copy::fill_to_words((HeapWord*)result, word_size, 0);
882 log_trace(metaspace)("Metaspace::allocate: type %d return " PTR_FORMAT ".", (int)type, p2i(result));
883 }
884
885 return result;
886 }
887
888 MetaWord* Metaspace::allocate(ClassLoaderData* loader_data, size_t word_size,
889 MetaspaceObj::Type type, TRAPS) {
890
891 if (HAS_PENDING_EXCEPTION) {
892 assert(false, "Should not allocate with exception pending");
893 return nullptr; // caller does a CHECK_NULL too
894 }
895 assert(!THREAD->owns_locks(), "allocating metaspace while holding mutex");
896
897 MetaWord* result = allocate(loader_data, word_size, type);
898
899 if (result == nullptr) {
900 MetadataType mdtype = (type == MetaspaceObj::ClassType) ? ClassType : NonClassType;
901 tracer()->report_metaspace_allocation_failure(loader_data, word_size, type, mdtype);
902
903 // Allocation failed.
904 if (is_init_completed()) {
905 // Only start a GC if the bootstrapping has completed.
906 // Try to clean out some heap memory and retry. This can prevent premature
907 // expansion of the metaspace.
908 result = Universe::heap()->satisfy_failed_metadata_allocation(loader_data, word_size, mdtype);
909 }
910
911 if (result == nullptr) {
912 report_metadata_oome(loader_data, word_size, type, mdtype, THREAD);
913 assert(HAS_PENDING_EXCEPTION, "sanity");
914 return nullptr;
915 }
916
917 // Zero initialize.
918 Copy::fill_to_words((HeapWord*)result, word_size, 0);
919
920 log_trace(metaspace)("Metaspace::allocate: type %d return " PTR_FORMAT ".", (int)type, p2i(result));
921 }
922
923 return result;
924 }
925
926 void Metaspace::report_metadata_oome(ClassLoaderData* loader_data, size_t word_size, MetaspaceObj::Type type, MetadataType mdtype, TRAPS) {
927 tracer()->report_metadata_oom(loader_data, word_size, type, mdtype);
928
929 // If result is still null, we are out of memory.
930 Log(gc, metaspace, freelist, oom) log;
931 if (log.is_info()) {
932 log.info("Metaspace (%s) allocation failed for size " SIZE_FORMAT,
933 is_class_space_allocation(mdtype) ? "class" : "data", word_size);
934 ResourceMark rm;
935 if (log.is_debug()) {
936 if (loader_data->metaspace_or_null() != nullptr) {
937 LogStream ls(log.debug());
938 loader_data->print_value_on(&ls);
939 }
940 }
941 LogStream ls(log.info());
942 // In case of an OOM, log out a short but still useful report.
943 MetaspaceUtils::print_basic_report(&ls, 0);
944 }
945
946 bool out_of_compressed_class_space = false;
947 if (is_class_space_allocation(mdtype)) {
948 ClassLoaderMetaspace* metaspace = loader_data->metaspace_non_null();
949 out_of_compressed_class_space =
950 MetaspaceUtils::committed_bytes(Metaspace::ClassType) +
951 align_up(word_size * BytesPerWord, 4 * M) >
952 CompressedClassSpaceSize;
953 }
954
955 // -XX:+HeapDumpOnOutOfMemoryError and -XX:OnOutOfMemoryError support
956 const char* space_string = out_of_compressed_class_space ?
957 "Compressed class space" : "Metaspace";
958
959 report_java_out_of_memory(space_string);
960
961 if (JvmtiExport::should_post_resource_exhausted()) {
962 JvmtiExport::post_resource_exhausted(
963 JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR,
964 space_string);
965 }
966
967 if (!is_init_completed()) {
968 vm_exit_during_initialization("OutOfMemoryError", space_string);
969 }
970
971 if (out_of_compressed_class_space) {
972 THROW_OOP(Universe::out_of_memory_error_class_metaspace());
973 } else {
974 THROW_OOP(Universe::out_of_memory_error_metaspace());
975 }
976 }
977
978 const char* Metaspace::metadata_type_name(Metaspace::MetadataType mdtype) {
979 switch (mdtype) {
980 case Metaspace::ClassType: return "Class";
981 case Metaspace::NonClassType: return "Metadata";
982 default:
983 assert(false, "Got bad mdtype: %d", (int) mdtype);
984 return nullptr;
985 }
986 }
987
988 void Metaspace::purge(bool classes_unloaded) {
989 // The MetaspaceCritical_lock is used by a concurrent GC to block out concurrent metaspace
990 // allocations, that would starve critical metaspace allocations, that are about to throw
991 // OOM if they fail; they need precedence for correctness.
992 MutexLocker ml(MetaspaceCritical_lock, Mutex::_no_safepoint_check_flag);
993 if (classes_unloaded) {
994 ChunkManager* cm = ChunkManager::chunkmanager_nonclass();
995 if (cm != nullptr) {
996 cm->purge();
997 }
998 if (using_class_space()) {
999 cm = ChunkManager::chunkmanager_class();
1000 if (cm != nullptr) {
1001 cm->purge();
1002 }
1003 }
1004 }
1005
1006 // Try to satisfy queued metaspace allocation requests.
1007 //
1008 // It might seem unnecessary to try to process allocation requests if no
1009 // classes have been unloaded. However, this call is required for the code
1010 // in MetaspaceCriticalAllocation::try_allocate_critical to work.
1011 MetaspaceCriticalAllocation::process();
1012 }
1013
1014 // Returns true if pointer points into one of the metaspace regions, or
1015 // into the class space.
1016 bool Metaspace::is_in_shared_metaspace(const void* ptr) {
1017 return MetaspaceShared::is_in_shared_metaspace(ptr);
1018 }
1019
1020 // Returns true if pointer points into one of the non-class-space metaspace regions.
1021 bool Metaspace::is_in_nonclass_metaspace(const void* ptr) {
1022 return VirtualSpaceList::vslist_nonclass()->contains((MetaWord*)ptr);
1023 }