1 /*
2 * Copyright (c) 2011, 2025, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2017, 2021 SAP SE. All rights reserved.
4 * Copyright (c) 2023, 2025, 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 "cds/cdsConfig.hpp"
28 #include "cds/metaspaceShared.hpp"
29 #include "classfile/classLoaderData.hpp"
30 #include "gc/shared/collectedHeap.hpp"
31 #include "logging/log.hpp"
32 #include "logging/logStream.hpp"
33 #include "memory/classLoaderMetaspace.hpp"
34 #include "memory/memoryReserver.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/metachunk.hpp"
41 #include "memory/metaspace/metaspaceCommon.hpp"
42 #include "memory/metaspace/metaspaceContext.hpp"
43 #include "memory/metaspace/metaspaceReporter.hpp"
44 #include "memory/metaspace/metaspaceSettings.hpp"
45 #include "memory/metaspace/runningCounters.hpp"
46 #include "memory/metaspace/virtualSpaceList.hpp"
47 #include "memory/metaspaceCriticalAllocation.hpp"
48 #include "memory/metaspaceStats.hpp"
49 #include "memory/metaspaceTracer.hpp"
50 #include "memory/metaspaceUtils.hpp"
51 #include "memory/resourceArea.hpp"
52 #include "memory/universe.hpp"
53 #include "nmt/memTracker.hpp"
54 #include "oops/compressedKlass.inline.hpp"
55 #include "oops/compressedOops.hpp"
56 #include "prims/jvmtiExport.hpp"
57 #include "runtime/atomic.hpp"
58 #include "runtime/globals_extension.hpp"
59 #include "runtime/init.hpp"
60 #include "runtime/java.hpp"
61 #include "runtime/mutexLocker.hpp"
62 #include "utilities/copy.hpp"
63 #include "utilities/debug.hpp"
64 #include "utilities/formatBuffer.hpp"
65 #include "utilities/globalDefinitions.hpp"
66 #include "utilities/ostream.hpp"
67
68 using metaspace::ChunkManager;
69 using metaspace::CommitLimiter;
70 using metaspace::MetaspaceContext;
71 using metaspace::MetaspaceReporter;
72 using metaspace::RunningCounters;
73 using metaspace::VirtualSpaceList;
74
75 size_t MetaspaceUtils::used_words() {
76 return RunningCounters::used_words();
77 }
78
79 size_t MetaspaceUtils::used_words(Metaspace::MetadataType mdtype) {
80 return mdtype == Metaspace::ClassType ? RunningCounters::used_words_class() : RunningCounters::used_words_nonclass();
81 }
82
83 size_t MetaspaceUtils::reserved_words() {
84 return RunningCounters::reserved_words();
85 }
86
87 size_t MetaspaceUtils::reserved_words(Metaspace::MetadataType mdtype) {
88 return mdtype == Metaspace::ClassType ? RunningCounters::reserved_words_class() : RunningCounters::reserved_words_nonclass();
89 }
90
91 size_t MetaspaceUtils::committed_words() {
92 return RunningCounters::committed_words();
93 }
94
95 size_t MetaspaceUtils::committed_words(Metaspace::MetadataType mdtype) {
96 return mdtype == Metaspace::ClassType ? RunningCounters::committed_words_class() : RunningCounters::committed_words_nonclass();
97 }
98
99 // Helper for get_statistics()
100 static void get_values_for(Metaspace::MetadataType mdtype, size_t* reserved, size_t* committed, size_t* used) {
101 #define w2b(x) (x * sizeof(MetaWord))
102 if (mdtype == Metaspace::ClassType) {
103 *reserved = w2b(RunningCounters::reserved_words_class());
104 *committed = w2b(RunningCounters::committed_words_class());
105 *used = w2b(RunningCounters::used_words_class());
106 } else {
107 *reserved = w2b(RunningCounters::reserved_words_nonclass());
108 *committed = w2b(RunningCounters::committed_words_nonclass());
109 *used = w2b(RunningCounters::used_words_nonclass());
110 }
111 #undef w2b
112 }
113
114 // Retrieve all statistics in one go; make sure the values are consistent.
115 MetaspaceStats MetaspaceUtils::get_statistics(Metaspace::MetadataType mdtype) {
116
117 // Consistency:
118 // This function reads three values (reserved, committed, used) from different counters. These counters
119 // may (very rarely) be out of sync. This has been a source for intermittent test errors in the past
120 // (see e.g. JDK-8237872, JDK-8151460).
121 // - reserved and committed counter are updated under protection of Metaspace_lock; an inconsistency
122 // between them can be the result of a dirty read.
123 // - used is an atomic counter updated outside any lock range; there is no way to guarantee
124 // a clean read wrt the other two values.
125 // Reading these values under lock protection would would only help for the first case. Therefore
126 // we don't bother and just re-read several times, then give up and correct the values.
127
128 size_t r = 0, c = 0, u = 0; // Note: byte values.
129 get_values_for(mdtype, &r, &c, &u);
130 int retries = 10;
131 // If the first retrieval resulted in inconsistent values, retry a bit...
132 while ((r < c || c < u) && --retries >= 0) {
133 get_values_for(mdtype, &r, &c, &u);
134 }
135 if (c < u || r < c) { // still inconsistent.
136 // ... but not endlessly. If we don't get consistent values, correct them on the fly.
137 // The logic here is that we trust the used counter - its an atomic counter and whatever we see
138 // must have been the truth once - and from that we reconstruct a likely set of committed/reserved
139 // values.
140 metaspace::InternalStats::inc_num_inconsistent_stats();
141 if (c < u) {
142 c = align_up(u, Metaspace::commit_alignment());
143 }
144 if (r < c) {
145 r = align_up(c, Metaspace::reserve_alignment());
146 }
147 }
148 return MetaspaceStats(r, c, u);
149 }
150
151 MetaspaceCombinedStats MetaspaceUtils::get_combined_statistics() {
152 return MetaspaceCombinedStats(get_statistics(Metaspace::ClassType), get_statistics(Metaspace::NonClassType));
153 }
154
155 void MetaspaceUtils::print_metaspace_change(const MetaspaceCombinedStats& pre_meta_values) {
156 // Get values now:
157 const MetaspaceCombinedStats meta_values = get_combined_statistics();
158
159 // We print used and committed since these are the most useful at-a-glance vitals for Metaspace:
160 // - used tells you how much memory is actually used for metadata
161 // - committed tells you how much memory is committed for the purpose of metadata
162 // The difference between those two would be waste, which can have various forms (freelists,
163 // unused parts of committed chunks etc)
164 //
165 // Left out is reserved, since this is not as exciting as the first two values: for class space,
166 // it is a constant (to uninformed users, often confusingly large). For non-class space, it would
167 // be interesting since free chunks can be uncommitted, but for now it is left out.
168
169 if (Metaspace::using_class_space()) {
170 log_info(gc, metaspace)(HEAP_CHANGE_FORMAT" "
171 HEAP_CHANGE_FORMAT" "
172 HEAP_CHANGE_FORMAT,
173 HEAP_CHANGE_FORMAT_ARGS("Metaspace",
174 pre_meta_values.used(),
175 pre_meta_values.committed(),
176 meta_values.used(),
177 meta_values.committed()),
178 HEAP_CHANGE_FORMAT_ARGS("NonClass",
179 pre_meta_values.non_class_used(),
180 pre_meta_values.non_class_committed(),
181 meta_values.non_class_used(),
182 meta_values.non_class_committed()),
183 HEAP_CHANGE_FORMAT_ARGS("Class",
184 pre_meta_values.class_used(),
185 pre_meta_values.class_committed(),
186 meta_values.class_used(),
187 meta_values.class_committed()));
188 } else {
189 log_info(gc, metaspace)(HEAP_CHANGE_FORMAT,
190 HEAP_CHANGE_FORMAT_ARGS("Metaspace",
191 pre_meta_values.used(),
192 pre_meta_values.committed(),
193 meta_values.used(),
194 meta_values.committed()));
195 }
196 }
197
198 // This will print out a basic metaspace usage report but
199 // unlike print_report() is guaranteed not to lock or to walk the CLDG.
200 void MetaspaceUtils::print_basic_report(outputStream* out, size_t scale) {
201 MetaspaceReporter::print_basic_report(out, scale);
202 }
203
204 // Prints a report about the current metaspace state.
205 // Optional parts can be enabled via flags.
206 // Function will walk the CLDG and will lock the expand lock; if that is not
207 // convenient, use print_basic_report() instead.
208 void MetaspaceUtils::print_report(outputStream* out, size_t scale) {
209 const int flags =
210 (int)MetaspaceReporter::Option::ShowLoaders |
211 (int)MetaspaceReporter::Option::BreakDownByChunkType |
212 (int)MetaspaceReporter::Option::ShowClasses;
213 MetaspaceReporter::print_report(out, scale, flags);
214 }
215
216 void MetaspaceUtils::print_on(outputStream* out) {
217
218 // First prints out totals, then, separately, the class space portion.
219 MetaspaceCombinedStats stats = get_combined_statistics();
220 out->print("Metaspace ");
221 out->fill_to(17);
222 out->print_cr("used %zuK, "
223 "committed %zuK, "
224 "reserved %zuK",
225 stats.used()/K,
226 stats.committed()/K,
227 stats.reserved()/K);
228
229 if (Metaspace::using_class_space()) {
230 StreamAutoIndentor indentor(out, 1);
231 out->print("class space ");
232 out->fill_to(17);
233 out->print_cr("used %zuK, "
234 "committed %zuK, "
235 "reserved %zuK",
236 stats.class_space_stats().used()/K,
237 stats.class_space_stats().committed()/K,
238 stats.class_space_stats().reserved()/K);
239 }
240 }
241
242 #ifdef ASSERT
243 void MetaspaceUtils::verify() {
244 if (Metaspace::initialized()) {
245
246 // Verify non-class chunkmanager...
247 ChunkManager* cm = ChunkManager::chunkmanager_nonclass();
248 cm->verify();
249
250 // ... and space list.
251 VirtualSpaceList* vsl = VirtualSpaceList::vslist_nonclass();
252 vsl->verify();
253
254 if (Metaspace::using_class_space()) {
255 // If we use compressed class pointers, verify class chunkmanager...
256 cm = ChunkManager::chunkmanager_class();
257 cm->verify();
258
259 // ... and class spacelist.
260 vsl = VirtualSpaceList::vslist_class();
261 vsl->verify();
262 }
263
264 }
265 }
266 #endif
267
268 ////////////////////////////////7
269 // MetaspaceGC methods
270
271 volatile size_t MetaspaceGC::_capacity_until_GC = 0;
272 uint MetaspaceGC::_shrink_factor = 0;
273
274 // VM_CollectForMetadataAllocation is the vm operation used to GC.
275 // Within the VM operation after the GC the attempt to allocate the metadata
276 // should succeed. If the GC did not free enough space for the metaspace
277 // allocation, the HWM is increased so that another virtualspace will be
278 // allocated for the metadata. With perm gen the increase in the perm
279 // gen had bounds, MinMetaspaceExpansion and MaxMetaspaceExpansion. The
280 // metaspace policy uses those as the small and large steps for the HWM.
281 //
282 // After the GC the compute_new_size() for MetaspaceGC is called to
283 // resize the capacity of the metaspaces. The current implementation
284 // is based on the flags MinMetaspaceFreeRatio and MaxMetaspaceFreeRatio used
285 // to resize the Java heap by some GC's. New flags can be implemented
286 // if really needed. MinMetaspaceFreeRatio is used to calculate how much
287 // free space is desirable in the metaspace capacity to decide how much
288 // to increase the HWM. MaxMetaspaceFreeRatio is used to decide how much
289 // free space is desirable in the metaspace capacity before decreasing
290 // the HWM.
291
292 // Calculate the amount to increase the high water mark (HWM).
293 // Increase by a minimum amount (MinMetaspaceExpansion) so that
294 // another expansion is not requested too soon. If that is not
295 // enough to satisfy the allocation, increase by MaxMetaspaceExpansion.
296 // If that is still not enough, expand by the size of the allocation
297 // plus some.
298 size_t MetaspaceGC::delta_capacity_until_GC(size_t bytes) {
299 size_t min_delta = MinMetaspaceExpansion;
300 size_t max_delta = MaxMetaspaceExpansion;
301 size_t delta = align_up(bytes, Metaspace::commit_alignment());
302
303 if (delta <= min_delta) {
304 delta = min_delta;
305 } else if (delta <= max_delta) {
306 // Don't want to hit the high water mark on the next
307 // allocation so make the delta greater than just enough
308 // for this allocation.
309 delta = max_delta;
310 } else {
311 // This allocation is large but the next ones are probably not
312 // so increase by the minimum.
313 delta = delta + min_delta;
314 }
315
316 assert_is_aligned(delta, Metaspace::commit_alignment());
317
318 return delta;
319 }
320
321 size_t MetaspaceGC::capacity_until_GC() {
322 size_t value = Atomic::load_acquire(&_capacity_until_GC);
323 assert(value >= MetaspaceSize, "Not initialized properly?");
324 return value;
325 }
326
327 // Try to increase the _capacity_until_GC limit counter by v bytes.
328 // Returns true if it succeeded. It may fail if either another thread
329 // concurrently increased the limit or the new limit would be larger
330 // than MaxMetaspaceSize.
331 // On success, optionally returns new and old metaspace capacity in
332 // new_cap_until_GC and old_cap_until_GC respectively.
333 // On error, optionally sets can_retry to indicate whether if there is
334 // actually enough space remaining to satisfy the request.
335 bool MetaspaceGC::inc_capacity_until_GC(size_t v, size_t* new_cap_until_GC, size_t* old_cap_until_GC, bool* can_retry) {
336 assert_is_aligned(v, Metaspace::commit_alignment());
337
338 size_t old_capacity_until_GC = _capacity_until_GC;
339 size_t new_value = old_capacity_until_GC + v;
340
341 if (new_value < old_capacity_until_GC) {
342 // The addition wrapped around, set new_value to aligned max value.
343 new_value = align_down(max_uintx, Metaspace::reserve_alignment());
344 }
345
346 if (new_value > MaxMetaspaceSize) {
347 if (can_retry != nullptr) {
348 *can_retry = false;
349 }
350 return false;
351 }
352
353 if (can_retry != nullptr) {
354 *can_retry = true;
355 }
356 size_t prev_value = Atomic::cmpxchg(&_capacity_until_GC, old_capacity_until_GC, new_value);
357
358 if (old_capacity_until_GC != prev_value) {
359 return false;
360 }
361
362 if (new_cap_until_GC != nullptr) {
363 *new_cap_until_GC = new_value;
364 }
365 if (old_cap_until_GC != nullptr) {
366 *old_cap_until_GC = old_capacity_until_GC;
367 }
368 return true;
369 }
370
371 size_t MetaspaceGC::dec_capacity_until_GC(size_t v) {
372 assert_is_aligned(v, Metaspace::commit_alignment());
373
374 return Atomic::sub(&_capacity_until_GC, v);
375 }
376
377 void MetaspaceGC::initialize() {
378 // Set the high-water mark to MaxMetapaceSize during VM initializaton since
379 // we can't do a GC during initialization.
380 _capacity_until_GC = MaxMetaspaceSize;
381 }
382
383 void MetaspaceGC::post_initialize() {
384 // Reset the high-water mark once the VM initialization is done.
385 _capacity_until_GC = MAX2(MetaspaceUtils::committed_bytes(), MetaspaceSize);
386 }
387
388 bool MetaspaceGC::can_expand(size_t word_size, bool is_class) {
389 // Check if the compressed class space is full.
390 if (is_class && Metaspace::using_class_space()) {
391 size_t class_committed = MetaspaceUtils::committed_bytes(Metaspace::ClassType);
392 if (class_committed + word_size * BytesPerWord > CompressedClassSpaceSize) {
393 log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by %zu words (CompressedClassSpaceSize = %zu words)",
394 (is_class ? "class" : "non-class"), word_size, CompressedClassSpaceSize / sizeof(MetaWord));
395 return false;
396 }
397 }
398
399 // Check if the user has imposed a limit on the metaspace memory.
400 size_t committed_bytes = MetaspaceUtils::committed_bytes();
401 if (committed_bytes + word_size * BytesPerWord > MaxMetaspaceSize) {
402 log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by %zu words (MaxMetaspaceSize = %zu words)",
403 (is_class ? "class" : "non-class"), word_size, MaxMetaspaceSize / sizeof(MetaWord));
404 return false;
405 }
406
407 return true;
408 }
409
410 size_t MetaspaceGC::allowed_expansion() {
411 size_t committed_bytes = MetaspaceUtils::committed_bytes();
412 size_t capacity_until_gc = capacity_until_GC();
413
414 size_t left_until_max = MaxMetaspaceSize - committed_bytes;
415 // capacity_until_GC may have been decreased concurrently and may
416 // temporarily be lower than what metaspace has committed. Allow for that.
417 size_t left_until_GC = capacity_until_gc > committed_bytes ?
418 capacity_until_gc - committed_bytes : 0;
419 size_t left_to_commit = MIN2(left_until_GC, left_until_max);
420 log_trace(gc, metaspace, freelist)("allowed expansion words: %zu"
421 " (left_until_max: %zu, left_until_GC: %zu.",
422 left_to_commit / BytesPerWord, left_until_max / BytesPerWord, left_until_GC / BytesPerWord);
423
424 return left_to_commit / BytesPerWord;
425 }
426
427 void MetaspaceGC::compute_new_size() {
428 assert(_shrink_factor <= 100, "invalid shrink factor");
429 uint current_shrink_factor = _shrink_factor;
430 _shrink_factor = 0;
431
432 // Using committed_bytes() for used_after_gc is an overestimation, since the
433 // chunk free lists are included in committed_bytes() and the memory in an
434 // un-fragmented chunk free list is available for future allocations.
435 // However, if the chunk free lists becomes fragmented, then the memory may
436 // not be available for future allocations and the memory is therefore "in use".
437 // Including the chunk free lists in the definition of "in use" is therefore
438 // necessary. Not including the chunk free lists can cause capacity_until_GC to
439 // shrink below committed_bytes() and this has caused serious bugs in the past.
440 const double used_after_gc = (double)MetaspaceUtils::committed_bytes();
441 const size_t capacity_until_GC = MetaspaceGC::capacity_until_GC();
442
443 const double minimum_free_percentage = MinMetaspaceFreeRatio / 100.0;
444 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
445
446 const double min_tmp = used_after_gc / maximum_used_percentage;
447 size_t minimum_desired_capacity =
448 (size_t)MIN2(min_tmp, double(MaxMetaspaceSize));
449 // Don't shrink less than the initial generation size
450 minimum_desired_capacity = MAX2(minimum_desired_capacity,
451 MetaspaceSize);
452
453 log_trace(gc, metaspace)("MetaspaceGC::compute_new_size: ");
454 log_trace(gc, metaspace)(" minimum_free_percentage: %6.2f maximum_used_percentage: %6.2f",
455 minimum_free_percentage, maximum_used_percentage);
456 log_trace(gc, metaspace)(" used_after_gc : %6.1fKB", used_after_gc / (double) K);
457
458 size_t shrink_bytes = 0;
459 if (capacity_until_GC < minimum_desired_capacity) {
460 // If we have less capacity below the metaspace HWM, then
461 // increment the HWM.
462 size_t expand_bytes = minimum_desired_capacity - capacity_until_GC;
463 expand_bytes = align_up(expand_bytes, Metaspace::commit_alignment());
464 // Don't expand unless it's significant
465 if (expand_bytes >= MinMetaspaceExpansion) {
466 size_t new_capacity_until_GC = 0;
467 bool succeeded = MetaspaceGC::inc_capacity_until_GC(expand_bytes, &new_capacity_until_GC);
468 assert(succeeded, "Should always successfully increment HWM when at safepoint");
469
470 Metaspace::tracer()->report_gc_threshold(capacity_until_GC,
471 new_capacity_until_GC,
472 MetaspaceGCThresholdUpdater::ComputeNewSize);
473 log_trace(gc, metaspace)(" expanding: minimum_desired_capacity: %6.1fKB expand_bytes: %6.1fKB MinMetaspaceExpansion: %6.1fKB new metaspace HWM: %6.1fKB",
474 (double) minimum_desired_capacity / (double) K,
475 (double) expand_bytes / (double) K,
476 (double) MinMetaspaceExpansion / (double) K,
477 (double) new_capacity_until_GC / (double) K);
478 }
479 return;
480 }
481
482 // No expansion, now see if we want to shrink
483 // We would never want to shrink more than this
484 assert(capacity_until_GC >= minimum_desired_capacity,
485 "%zu >= %zu",
486 capacity_until_GC, minimum_desired_capacity);
487 size_t max_shrink_bytes = capacity_until_GC - minimum_desired_capacity;
488
489 // Should shrinking be considered?
490 if (MaxMetaspaceFreeRatio < 100) {
491 const double maximum_free_percentage = MaxMetaspaceFreeRatio / 100.0;
492 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
493 const double max_tmp = used_after_gc / minimum_used_percentage;
494 size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(MaxMetaspaceSize));
495 maximum_desired_capacity = MAX2(maximum_desired_capacity,
496 MetaspaceSize);
497 log_trace(gc, metaspace)(" maximum_free_percentage: %6.2f minimum_used_percentage: %6.2f",
498 maximum_free_percentage, minimum_used_percentage);
499 log_trace(gc, metaspace)(" minimum_desired_capacity: %6.1fKB maximum_desired_capacity: %6.1fKB",
500 (double) minimum_desired_capacity / (double) K, (double) maximum_desired_capacity / (double) K);
501
502 assert(minimum_desired_capacity <= maximum_desired_capacity,
503 "sanity check");
504
505 if (capacity_until_GC > maximum_desired_capacity) {
506 // Capacity too large, compute shrinking size
507 shrink_bytes = capacity_until_GC - maximum_desired_capacity;
508 // We don't want shrink all the way back to initSize if people call
509 // System.gc(), because some programs do that between "phases" and then
510 // we'd just have to grow the heap up again for the next phase. So we
511 // damp the shrinking: 0% on the first call, 10% on the second call, 40%
512 // on the third call, and 100% by the fourth call. But if we recompute
513 // size without shrinking, it goes back to 0%.
514 shrink_bytes = shrink_bytes / 100 * current_shrink_factor;
515
516 shrink_bytes = align_down(shrink_bytes, Metaspace::commit_alignment());
517
518 assert(shrink_bytes <= max_shrink_bytes,
519 "invalid shrink size %zu not <= %zu",
520 shrink_bytes, max_shrink_bytes);
521 if (current_shrink_factor == 0) {
522 _shrink_factor = 10;
523 } else {
524 _shrink_factor = MIN2(current_shrink_factor * 4, (uint) 100);
525 }
526 log_trace(gc, metaspace)(" shrinking: initThreshold: %.1fK maximum_desired_capacity: %.1fK",
527 (double) MetaspaceSize / (double) K, (double) maximum_desired_capacity / (double) K);
528 log_trace(gc, metaspace)(" shrink_bytes: %.1fK current_shrink_factor: %d new shrink factor: %d MinMetaspaceExpansion: %.1fK",
529 (double) shrink_bytes / (double) K, current_shrink_factor, _shrink_factor, (double) MinMetaspaceExpansion / (double) K);
530 }
531 }
532
533 // Don't shrink unless it's significant
534 if (shrink_bytes >= MinMetaspaceExpansion &&
535 ((capacity_until_GC - shrink_bytes) >= MetaspaceSize)) {
536 size_t new_capacity_until_GC = MetaspaceGC::dec_capacity_until_GC(shrink_bytes);
537 Metaspace::tracer()->report_gc_threshold(capacity_until_GC,
538 new_capacity_until_GC,
539 MetaspaceGCThresholdUpdater::ComputeNewSize);
540 }
541 }
542
543 ////// Metaspace methods /////
544
545 const MetaspaceTracer* Metaspace::_tracer = nullptr;
546 const void* Metaspace::_class_space_start = nullptr;
547 const void* Metaspace::_class_space_end = nullptr;
548
549 bool Metaspace::initialized() {
550 return metaspace::MetaspaceContext::context_nonclass() != nullptr
551 LP64_ONLY(&& (using_class_space() ? Metaspace::class_space_is_initialized() : true));
552 }
553
554 #ifdef _LP64
555
556 void Metaspace::print_compressed_class_space(outputStream* st) {
557 if (VirtualSpaceList::vslist_class() != nullptr) {
558 MetaWord* base = VirtualSpaceList::vslist_class()->base_of_first_node();
559 size_t size = VirtualSpaceList::vslist_class()->word_size_of_first_node();
560 MetaWord* top = base + size;
561 st->print("Compressed class space mapped at: " PTR_FORMAT "-" PTR_FORMAT ", reserved size: %zu",
562 p2i(base), p2i(top), (top - base) * BytesPerWord);
563 st->cr();
564 }
565 }
566
567 // Given a prereserved space, use that to set up the compressed class space list.
568 void Metaspace::initialize_class_space(ReservedSpace rs) {
569 assert(rs.size() >= CompressedClassSpaceSize,
570 "%zu != %zu", rs.size(), CompressedClassSpaceSize);
571 assert(using_class_space(), "Must be using class space");
572
573 assert(rs.size() == CompressedClassSpaceSize, "%zu != %zu",
574 rs.size(), CompressedClassSpaceSize);
575 assert(is_aligned(rs.base(), Metaspace::reserve_alignment()) &&
576 is_aligned(rs.size(), Metaspace::reserve_alignment()),
577 "wrong alignment");
578
579 MetaspaceContext::initialize_class_space_context(rs);
580 _class_space_start = rs.base();
581 _class_space_end = rs.end();
582 }
583
584 // Returns true if class space has been setup (initialize_class_space).
585 bool Metaspace::class_space_is_initialized() {
586 return MetaspaceContext::context_class() != nullptr;
587 }
588
589 // Reserve a range of memory that is to contain narrow Klass IDs. If "try_in_low_address_ranges"
590 // is true, we will attempt to reserve memory suitable for zero-based encoding.
591 ReservedSpace Metaspace::reserve_address_space_for_compressed_classes(size_t size, bool optimize_for_zero_base) {
592 char* result = nullptr;
593
594 NOT_ZERO(result =
595 (char*) CompressedKlassPointers::reserve_address_space_for_compressed_classes(size, RandomizeClassSpaceLocation,
596 optimize_for_zero_base));
597
598 if (result == nullptr) {
599 // Fallback: reserve anywhere
600 log_debug(metaspace, map)("Trying anywhere...");
601 result = os::reserve_memory_aligned(size, Metaspace::reserve_alignment(), mtClass);
602 }
603
604 // Wrap resulting range in ReservedSpace
605 if (result != nullptr) {
606 log_debug(metaspace, map)("Mapped at " PTR_FORMAT, p2i(result));
607 assert(is_aligned(result, Metaspace::reserve_alignment()), "Alignment too small for metaspace");
608
609 return ReservedSpace(result,
610 size,
611 Metaspace::reserve_alignment(),
612 os::vm_page_size(),
613 !ExecMem,
614 false /* special */);
615 } else {
616 log_debug(metaspace, map)("Failed to map.");
617 return {};
618 }
619 }
620 #endif // _LP64
621
622 size_t Metaspace::reserve_alignment_words() {
623 return metaspace::Settings::virtual_space_node_reserve_alignment_words();
624 }
625
626 size_t Metaspace::commit_alignment_words() {
627 return metaspace::Settings::commit_granule_words();
628 }
629
630 void Metaspace::ergo_initialize() {
631
632 // Must happen before using any setting from Settings::---
633 metaspace::Settings::ergo_initialize();
634
635 // MaxMetaspaceSize and CompressedClassSpaceSize:
636 //
637 // MaxMetaspaceSize is the maximum size, in bytes, of memory we are allowed
638 // to commit for the Metaspace.
639 // It is just a number; a limit we compare against before committing. It
640 // does not have to be aligned to anything.
641 // It gets used as compare value before attempting to increase the metaspace
642 // commit charge. It defaults to max_uintx (unlimited).
643 //
644 // CompressedClassSpaceSize is the size, in bytes, of the address range we
645 // pre-reserve for the compressed class space (if we use class space).
646 // This size has to be aligned to the metaspace reserve alignment (to the
647 // size of a root chunk). It gets aligned up from whatever value the caller
648 // gave us to the next multiple of root chunk size.
649 //
650 // Note: Strictly speaking MaxMetaspaceSize and CompressedClassSpaceSize have
651 // very little to do with each other. The notion often encountered:
652 // MaxMetaspaceSize = CompressedClassSpaceSize + <non-class metadata size>
653 // is subtly wrong: MaxMetaspaceSize can besmaller than CompressedClassSpaceSize,
654 // in which case we just would not be able to fully commit the class space range.
655 //
656 // We still adjust CompressedClassSpaceSize to reasonable limits, mainly to
657 // save on reserved space, and to make ergnonomics less confusing.
658
659 MaxMetaspaceSize = MAX2(MaxMetaspaceSize, commit_alignment());
660
661 if (UseCompressedClassPointers) {
662 // Let Class Space not be larger than 80% of MaxMetaspaceSize. Note that is
663 // grossly over-dimensioned for most usage scenarios; typical ratio of
664 // class space : non class space usage is about 1:6. With many small classes,
665 // it can get as low as 1:2. It is not a big deal though since ccs is only
666 // reserved and will be committed on demand only.
667 const size_t max_ccs_size = 8 * (MaxMetaspaceSize / 10);
668
669 // Sanity check.
670 const size_t max_klass_range = CompressedKlassPointers::max_klass_range_size();
671 assert(max_klass_range >= reserve_alignment(),
672 "Klass range (%zu) must cover at least a full root chunk (%zu)",
673 max_klass_range, reserve_alignment());
674
675 size_t adjusted_ccs_size = MIN3(CompressedClassSpaceSize, max_ccs_size, max_klass_range);
676
677 // CCS must be aligned to root chunk size, and be at least the size of one
678 // root chunk.
679 adjusted_ccs_size = align_up(adjusted_ccs_size, reserve_alignment());
680 adjusted_ccs_size = MAX2(adjusted_ccs_size, reserve_alignment());
681
682 // Print a warning if the adjusted size differs from the users input
683 if (CompressedClassSpaceSize != adjusted_ccs_size) {
684 #define X "CompressedClassSpaceSize adjusted from user input " \
685 "%zu bytes to %zu bytes", CompressedClassSpaceSize, adjusted_ccs_size
686 if (FLAG_IS_CMDLINE(CompressedClassSpaceSize)) {
687 log_warning(metaspace)(X);
688 } else {
689 log_info(metaspace)(X);
690 }
691 #undef X
692 }
693
694 // Note: re-adjusting may have us left with a CompressedClassSpaceSize
695 // larger than MaxMetaspaceSize for very small values of MaxMetaspaceSize.
696 // Lets just live with that, its not a big deal.
697 if (adjusted_ccs_size != CompressedClassSpaceSize) {
698 FLAG_SET_ERGO(CompressedClassSpaceSize, adjusted_ccs_size);
699 log_info(metaspace)("Setting CompressedClassSpaceSize to %zu.",
700 CompressedClassSpaceSize);
701 }
702 }
703
704 // Set MetaspaceSize, MinMetaspaceExpansion and MaxMetaspaceExpansion
705 if (MetaspaceSize > MaxMetaspaceSize) {
706 MetaspaceSize = MaxMetaspaceSize;
707 }
708
709 MetaspaceSize = align_down_bounded(MetaspaceSize, commit_alignment());
710
711 assert(MetaspaceSize <= MaxMetaspaceSize, "MetaspaceSize should be limited by MaxMetaspaceSize");
712
713 MinMetaspaceExpansion = align_down_bounded(MinMetaspaceExpansion, commit_alignment());
714 MaxMetaspaceExpansion = align_down_bounded(MaxMetaspaceExpansion, commit_alignment());
715
716 }
717
718 void Metaspace::global_initialize() {
719 MetaspaceGC::initialize(); // <- since we do not prealloc init chunks anymore is this still needed?
720
721 metaspace::ChunkHeaderPool::initialize();
722
723 if (CDSConfig::is_dumping_static_archive()) {
724 if (!CDSConfig::is_dumping_final_static_archive()) {
725 assert(!CDSConfig::is_using_archive(), "sanity");
726 }
727 MetaspaceShared::initialize_for_static_dump();
728 }
729
730 // If UseCompressedClassPointers=1, we have two cases:
731 // a) if CDS is active (runtime, Xshare=on), it will create the class space
732 // for us, initialize it and set up CompressedKlassPointers encoding.
733 // Class space will be reserved above the mapped archives.
734 // b) if CDS either deactivated (Xshare=off) or a static dump is to be done (Xshare:dump),
735 // we will create the class space on our own. It will be placed above the java heap,
736 // since we assume it has been placed in low
737 // address regions. We may rethink this (see JDK-8244943). Failing that,
738 // it will be placed anywhere.
739
740 #if INCLUDE_CDS
741 // case (a)
742 if (CDSConfig::is_using_archive()) {
743 if (!FLAG_IS_DEFAULT(CompressedClassSpaceBaseAddress)) {
744 log_warning(metaspace)("CDS active - ignoring CompressedClassSpaceBaseAddress.");
745 }
746 MetaspaceShared::initialize_runtime_shared_and_meta_spaces();
747 // If any of the archived space fails to map, UseSharedSpaces
748 // is reset to false.
749 }
750 #endif // INCLUDE_CDS
751
752 #ifdef _LP64
753
754 if (using_class_space() && !class_space_is_initialized()) {
755 assert(!CDSConfig::is_using_archive(), "CDS archive is not mapped at this point");
756
757 // case (b) (No CDS)
758 ReservedSpace rs;
759 const size_t size = align_up(CompressedClassSpaceSize, Metaspace::reserve_alignment());
760
761 // If CompressedClassSpaceBaseAddress is set, we attempt to force-map class space to
762 // the given address. This is a debug-only feature aiding tests. Due to the ASLR lottery
763 // this may fail, in which case the VM will exit after printing an appropriate message.
764 // Tests using this switch should cope with that.
765 if (CompressedClassSpaceBaseAddress != 0) {
766 const address base = (address)CompressedClassSpaceBaseAddress;
767 if (!is_aligned(base, Metaspace::reserve_alignment())) {
768 vm_exit_during_initialization(
769 err_msg("CompressedClassSpaceBaseAddress=" PTR_FORMAT " invalid "
770 "(must be aligned to 0x%zx).",
771 CompressedClassSpaceBaseAddress, Metaspace::reserve_alignment()));
772 }
773
774 rs = MemoryReserver::reserve((char*)base,
775 size,
776 Metaspace::reserve_alignment(),
777 os::vm_page_size(),
778 mtClass);
779
780 if (rs.is_reserved()) {
781 log_info(metaspace)("Successfully forced class space address to " PTR_FORMAT, p2i(base));
782 } else {
783 LogTarget(Debug, metaspace) lt;
784 if (lt.is_enabled()) {
785 LogStream ls(lt);
786 os::print_memory_mappings((char*)base, size, &ls);
787 }
788 vm_exit_during_initialization(
789 err_msg("CompressedClassSpaceBaseAddress=" PTR_FORMAT " given, but reserving class space failed.",
790 CompressedClassSpaceBaseAddress));
791 }
792 }
793
794 // ...failing that, reserve anywhere, but let platform do optimized placement:
795 if (!rs.is_reserved()) {
796 log_info(metaspace)("Reserving compressed class space anywhere");
797 rs = Metaspace::reserve_address_space_for_compressed_classes(size, true);
798 }
799
800 // ...failing that, give up.
801 if (!rs.is_reserved()) {
802 vm_exit_during_initialization(
803 err_msg("Could not allocate compressed class space: %zu bytes",
804 CompressedClassSpaceSize));
805 }
806
807 // Mark class space as such
808 MemTracker::record_virtual_memory_tag(rs, mtClass);
809
810 // Initialize space
811 Metaspace::initialize_class_space(rs);
812
813 // Set up compressed class pointer encoding.
814 // In CDS=off mode, we give the JVM some leeway to choose a favorable base/shift combination.
815 CompressedKlassPointers::initialize((address)rs.base(), rs.size());
816
817 // After narrowKlass encoding scheme is decided: if the encoding base points to class space start,
818 // establish a protection zone. Accidentally decoding a zero nKlass ID and then using it will result
819 // in an immediate segmentation fault instead of a delayed error much later.
820 if (CompressedKlassPointers::base() == (address)rs.base()) {
821 // Let the protection zone be a whole commit granule. Otherwise, buddy allocator may later place neighboring
822 // chunks in the same granule, see that the granule is not yet committed, and commit it, which would replace
823 // the protection mapping and make the zone readable.
824 // Alternatively, we could commit the chunk right now, but that is a tiny bit more fiddly, since we are not
825 // fully set up yet at this point.
826 const size_t protzone_size = metaspace::Settings::commit_granule_bytes(); // granule size >= page size
827 const size_t protzone_wordsize = protzone_size / BytesPerWord;
828 const metaspace::chunklevel_t lvl = metaspace::chunklevel::level_fitting_word_size(protzone_wordsize);
829 metaspace::Metachunk* const chunk = MetaspaceContext::context_class()->cm()->get_chunk(lvl);
830 const address protzone = (address) chunk->base();
831 assert(protzone == (address)rs.base(), "The very first chunk should be located at the class space start?");
832 assert(chunk->word_size() == protzone_wordsize, "Weird chunk size");
833 CompressedKlassPointers::establish_protection_zone(protzone, protzone_size);
834 } else {
835 assert(CompressedKlassPointers::base() == nullptr, "Zero-based encoding expected");
836 }
837
838 }
839
840 #endif // _LP64
841
842 // Initialize non-class virtual space list, and its chunk manager:
843 MetaspaceContext::initialize_nonclass_space_context();
844
845 _tracer = new MetaspaceTracer();
846
847 #ifdef _LP64
848 if (UseCompressedClassPointers) {
849 // Note: "cds" would be a better fit but keep this for backward compatibility.
850 LogTarget(Info, gc, metaspace) lt;
851 if (lt.is_enabled()) {
852 LogStream ls(lt);
853 CDS_ONLY(MetaspaceShared::print_on(&ls);)
854 Metaspace::print_compressed_class_space(&ls);
855 CompressedKlassPointers::print_mode(&ls);
856 }
857 }
858 #endif
859
860 }
861
862 void Metaspace::post_initialize() {
863 MetaspaceGC::post_initialize();
864 }
865
866 size_t Metaspace::max_allocation_word_size() {
867 return metaspace::chunklevel::MAX_CHUNK_WORD_SIZE;
868 }
869
870 // This version of Metaspace::allocate does not throw OOM but simply returns null, and
871 // is suitable for calling from non-Java threads.
872 // Callers are responsible for checking null.
873 MetaWord* Metaspace::allocate(ClassLoaderData* loader_data, size_t word_size,
874 MetaspaceObj::Type type, bool use_class_space) {
875 assert(word_size <= Metaspace::max_allocation_word_size(),
876 "allocation size too large (%zu)", word_size);
877
878 assert(loader_data != nullptr, "Should never pass around a null loader_data. "
879 "ClassLoaderData::the_null_class_loader_data() should have been used.");
880
881 // Deal with concurrent unloading failed allocation starvation
882 MetaspaceCriticalAllocation::block_if_concurrent_purge();
883
884 MetadataType mdtype = use_class_space ? ClassType : NonClassType;
885
886 // Try to allocate metadata.
887 MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
888
889 if (result != nullptr) {
890 #ifdef ASSERT
891 if (using_class_space() && mdtype == ClassType) {
892 assert(is_in_class_space(result) &&
893 is_aligned(result, CompressedKlassPointers::klass_alignment_in_bytes()), "Sanity");
894 } else {
895 assert((is_in_class_space(result) || is_in_nonclass_metaspace(result)) &&
896 is_aligned(result, Metaspace::min_allocation_alignment_bytes), "Sanity");
897 }
898 #endif
899 // Zero initialize.
900 Copy::fill_to_words((HeapWord*)result, word_size, 0);
901 log_trace(metaspace)("Metaspace::allocate: type %d return " PTR_FORMAT ".", (int)type, p2i(result));
902 }
903
904 return result;
905 }
906
907 MetaWord* Metaspace::allocate(ClassLoaderData* loader_data, size_t word_size,
908 MetaspaceObj::Type type, bool use_class_space, TRAPS) {
909
910 if (HAS_PENDING_EXCEPTION) {
911 assert(false, "Should not allocate with exception pending");
912 return nullptr; // caller does a CHECK_NULL too
913 }
914 //leyden/premain: temporarily disabled due to JDK-8327737
915 assert(!THREAD->owns_locks(), "allocating metaspace while holding mutex");
916
917 MetaWord* result = allocate(loader_data, word_size, type, use_class_space);
918
919 if (result == nullptr) {
920 MetadataType mdtype = use_class_space ? ClassType : NonClassType;
921 tracer()->report_metaspace_allocation_failure(loader_data, word_size, type, mdtype);
922
923 // Allocation failed.
924 if (is_init_completed()) {
925 // Only start a GC if the bootstrapping has completed.
926 // Try to clean out some heap memory and retry. This can prevent premature
927 // expansion of the metaspace.
928 result = Universe::heap()->satisfy_failed_metadata_allocation(loader_data, word_size, mdtype);
929 }
930
931 if (result == nullptr) {
932 report_metadata_oome(loader_data, word_size, type, mdtype, THREAD);
933 assert(HAS_PENDING_EXCEPTION, "sanity");
934 return nullptr;
935 }
936
937 // Zero initialize.
938 Copy::fill_to_words((HeapWord*)result, word_size, 0);
939
940 log_trace(metaspace)("Metaspace::allocate: type %d return " PTR_FORMAT ".", (int)type, p2i(result));
941 }
942
943 return result;
944 }
945
946 void Metaspace::report_metadata_oome(ClassLoaderData* loader_data, size_t word_size, MetaspaceObj::Type type, MetadataType mdtype, TRAPS) {
947 tracer()->report_metadata_oom(loader_data, word_size, type, mdtype);
948
949 // If result is still null, we are out of memory.
950 {
951 LogMessage(gc, metaspace, freelist, oom) log;
952 if (log.is_info()) {
953 log.info("Metaspace (%s) allocation failed for size %zu",
954 is_class_space_allocation(mdtype) ? "class" : "data", word_size);
955 ResourceMark rm;
956 if (log.is_debug()) {
957 if (loader_data->metaspace_or_null() != nullptr) {
958 NonInterleavingLogStream ls(LogLevelType::Debug, log);
959 loader_data->print_value_on(&ls);
960 }
961 }
962 NonInterleavingLogStream ls(LogLevelType::Info, log);
963 // In case of an OOM, log out a short but still useful report.
964 MetaspaceUtils::print_basic_report(&ls, 0);
965 }
966 }
967
968 bool out_of_compressed_class_space = false;
969 if (is_class_space_allocation(mdtype)) {
970 ClassLoaderMetaspace* metaspace = loader_data->metaspace_non_null();
971 out_of_compressed_class_space =
972 MetaspaceUtils::committed_bytes(Metaspace::ClassType) +
973 align_up(word_size * BytesPerWord, 4 * M) >
974 CompressedClassSpaceSize;
975 }
976
977 // -XX:+HeapDumpOnOutOfMemoryError and -XX:OnOutOfMemoryError support
978 const char* space_string = out_of_compressed_class_space ?
979 "Compressed class space" : "Metaspace";
980
981 report_java_out_of_memory(space_string);
982
983 if (JvmtiExport::should_post_resource_exhausted()) {
984 JvmtiExport::post_resource_exhausted(
985 JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR,
986 space_string);
987 }
988
989 if (!is_init_completed()) {
990 vm_exit_during_initialization("OutOfMemoryError", space_string);
991 }
992
993 if (out_of_compressed_class_space) {
994 THROW_OOP(Universe::out_of_memory_error_class_metaspace());
995 } else {
996 THROW_OOP(Universe::out_of_memory_error_metaspace());
997 }
998 }
999
1000 const char* Metaspace::metadata_type_name(Metaspace::MetadataType mdtype) {
1001 switch (mdtype) {
1002 case Metaspace::ClassType: return "Class";
1003 case Metaspace::NonClassType: return "Metadata";
1004 default:
1005 assert(false, "Got bad mdtype: %d", (int) mdtype);
1006 return nullptr;
1007 }
1008 }
1009
1010 void Metaspace::purge(bool classes_unloaded) {
1011 // The MetaspaceCritical_lock is used by a concurrent GC to block out concurrent metaspace
1012 // allocations, that would starve critical metaspace allocations, that are about to throw
1013 // OOM if they fail; they need precedence for correctness.
1014 MutexLocker ml(MetaspaceCritical_lock, Mutex::_no_safepoint_check_flag);
1015 if (classes_unloaded) {
1016 ChunkManager* cm = ChunkManager::chunkmanager_nonclass();
1017 if (cm != nullptr) {
1018 cm->purge();
1019 }
1020 if (using_class_space()) {
1021 cm = ChunkManager::chunkmanager_class();
1022 if (cm != nullptr) {
1023 cm->purge();
1024 }
1025 }
1026 }
1027
1028 // Try to satisfy queued metaspace allocation requests.
1029 //
1030 // It might seem unnecessary to try to process allocation requests if no
1031 // classes have been unloaded. However, this call is required for the code
1032 // in MetaspaceCriticalAllocation::try_allocate_critical to work.
1033 MetaspaceCriticalAllocation::process();
1034 }
1035
1036
1037 // Returns true if pointer points into one of the metaspace regions, or
1038 // into the class space.
1039 bool Metaspace::is_in_shared_metaspace(const void* ptr) {
1040 return MetaspaceShared::is_in_shared_metaspace(ptr);
1041 }
1042
1043 // Returns true if pointer points into one of the non-class-space metaspace regions.
1044 bool Metaspace::is_in_nonclass_metaspace(const void* ptr) {
1045 return VirtualSpaceList::vslist_nonclass()->contains((MetaWord*)ptr);
1046 }