1 /*
2 * Copyright (c) 2011, 2023, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2017, 2021 SAP SE. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #include "precompiled.hpp"
27 #include "cds/metaspaceShared.hpp"
28 #include "classfile/classLoaderData.hpp"
29 #include "gc/shared/collectedHeap.hpp"
30 #include "logging/log.hpp"
31 #include "logging/logStream.hpp"
32 #include "memory/classLoaderMetaspace.hpp"
33 #include "memory/metaspace.hpp"
34 #include "memory/metaspaceCriticalAllocation.hpp"
35 #include "memory/metaspace/chunkHeaderPool.hpp"
36 #include "memory/metaspace/chunkManager.hpp"
37 #include "memory/metaspace/commitLimiter.hpp"
38 #include "memory/metaspace/internalStats.hpp"
39 #include "memory/metaspace/metaspaceCommon.hpp"
40 #include "memory/metaspace/metaspaceContext.hpp"
41 #include "memory/metaspace/metaspaceReporter.hpp"
42 #include "memory/metaspace/metaspaceSettings.hpp"
43 #include "memory/metaspace/runningCounters.hpp"
44 #include "memory/metaspace/virtualSpaceList.hpp"
45 #include "memory/metaspaceTracer.hpp"
46 #include "memory/metaspaceStats.hpp"
47 #include "memory/metaspaceUtils.hpp"
48 #include "memory/resourceArea.hpp"
49 #include "memory/universe.hpp"
50 #include "oops/compressedOops.hpp"
51 #include "prims/jvmtiExport.hpp"
52 #include "runtime/atomic.hpp"
53 #include "runtime/globals_extension.hpp"
54 #include "runtime/init.hpp"
55 #include "runtime/java.hpp"
56 #include "services/memTracker.hpp"
57 #include "utilities/copy.hpp"
58 #include "utilities/debug.hpp"
59 #include "utilities/formatBuffer.hpp"
60 #include "utilities/globalDefinitions.hpp"
61
62 using metaspace::ChunkManager;
63 using metaspace::CommitLimiter;
64 using metaspace::MetaspaceContext;
65 using metaspace::MetaspaceReporter;
66 using metaspace::RunningCounters;
67 using metaspace::VirtualSpaceList;
68
69 size_t MetaspaceUtils::used_words() {
70 return RunningCounters::used_words();
71 }
72
73 size_t MetaspaceUtils::used_words(Metaspace::MetadataType mdtype) {
74 return mdtype == Metaspace::ClassType ? RunningCounters::used_words_class() : RunningCounters::used_words_nonclass();
75 }
76
77 size_t MetaspaceUtils::reserved_words() {
78 return RunningCounters::reserved_words();
79 }
80
81 size_t MetaspaceUtils::reserved_words(Metaspace::MetadataType mdtype) {
82 return mdtype == Metaspace::ClassType ? RunningCounters::reserved_words_class() : RunningCounters::reserved_words_nonclass();
83 }
84
85 size_t MetaspaceUtils::committed_words() {
86 return RunningCounters::committed_words();
87 }
88
89 size_t MetaspaceUtils::committed_words(Metaspace::MetadataType mdtype) {
90 return mdtype == Metaspace::ClassType ? RunningCounters::committed_words_class() : RunningCounters::committed_words_nonclass();
91 }
92
93 // Helper for get_statistics()
94 static void get_values_for(Metaspace::MetadataType mdtype, size_t* reserved, size_t* committed, size_t* used) {
95 #define w2b(x) (x * sizeof(MetaWord))
96 if (mdtype == Metaspace::ClassType) {
97 *reserved = w2b(RunningCounters::reserved_words_class());
98 *committed = w2b(RunningCounters::committed_words_class());
99 *used = w2b(RunningCounters::used_words_class());
100 } else {
101 *reserved = w2b(RunningCounters::reserved_words_nonclass());
102 *committed = w2b(RunningCounters::committed_words_nonclass());
103 *used = w2b(RunningCounters::used_words_nonclass());
104 }
105 #undef w2b
106 }
107
108 // Retrieve all statistics in one go; make sure the values are consistent.
109 MetaspaceStats MetaspaceUtils::get_statistics(Metaspace::MetadataType mdtype) {
110
111 // Consistency:
112 // This function reads three values (reserved, committed, used) from different counters. These counters
113 // may (very rarely) be out of sync. This has been a source for intermittent test errors in the past
114 // (see e.g. JDK-8237872, JDK-8151460).
115 // - reserved and committed counter are updated under protection of Metaspace_lock; an inconsistency
116 // between them can be the result of a dirty read.
117 // - used is an atomic counter updated outside any lock range; there is no way to guarantee
118 // a clean read wrt the other two values.
119 // Reading these values under lock protection would would only help for the first case. Therefore
120 // we don't bother and just re-read several times, then give up and correct the values.
121
122 size_t r = 0, c = 0, u = 0; // Note: byte values.
123 get_values_for(mdtype, &r, &c, &u);
124 int retries = 10;
125 // If the first retrieval resulted in inconsistent values, retry a bit...
126 while ((r < c || c < u) && --retries >= 0) {
127 get_values_for(mdtype, &r, &c, &u);
128 }
129 if (c < u || r < c) { // still inconsistent.
130 // ... but not endlessly. If we don't get consistent values, correct them on the fly.
131 // The logic here is that we trust the used counter - its an atomic counter and whatever we see
132 // must have been the truth once - and from that we reconstruct a likely set of committed/reserved
133 // values.
134 metaspace::InternalStats::inc_num_inconsistent_stats();
135 if (c < u) {
136 c = align_up(u, Metaspace::commit_alignment());
137 }
138 if (r < c) {
139 r = align_up(c, Metaspace::reserve_alignment());
140 }
141 }
142 return MetaspaceStats(r, c, u);
143 }
144
145 MetaspaceCombinedStats MetaspaceUtils::get_combined_statistics() {
146 return MetaspaceCombinedStats(get_statistics(Metaspace::ClassType), get_statistics(Metaspace::NonClassType));
147 }
148
149 void MetaspaceUtils::print_metaspace_change(const MetaspaceCombinedStats& pre_meta_values) {
150 // Get values now:
151 const MetaspaceCombinedStats meta_values = get_combined_statistics();
152
153 // We print used and committed since these are the most useful at-a-glance vitals for Metaspace:
154 // - used tells you how much memory is actually used for metadata
155 // - committed tells you how much memory is committed for the purpose of metadata
156 // The difference between those two would be waste, which can have various forms (freelists,
157 // unused parts of committed chunks etc)
158 //
159 // Left out is reserved, since this is not as exciting as the first two values: for class space,
160 // it is a constant (to uninformed users, often confusingly large). For non-class space, it would
161 // be interesting since free chunks can be uncommitted, but for now it is left out.
162
163 if (Metaspace::using_class_space()) {
164 log_info(gc, metaspace)(HEAP_CHANGE_FORMAT" "
165 HEAP_CHANGE_FORMAT" "
166 HEAP_CHANGE_FORMAT,
167 HEAP_CHANGE_FORMAT_ARGS("Metaspace",
168 pre_meta_values.used(),
169 pre_meta_values.committed(),
170 meta_values.used(),
171 meta_values.committed()),
172 HEAP_CHANGE_FORMAT_ARGS("NonClass",
173 pre_meta_values.non_class_used(),
174 pre_meta_values.non_class_committed(),
175 meta_values.non_class_used(),
176 meta_values.non_class_committed()),
177 HEAP_CHANGE_FORMAT_ARGS("Class",
178 pre_meta_values.class_used(),
179 pre_meta_values.class_committed(),
180 meta_values.class_used(),
181 meta_values.class_committed()));
182 } else {
183 log_info(gc, metaspace)(HEAP_CHANGE_FORMAT,
184 HEAP_CHANGE_FORMAT_ARGS("Metaspace",
185 pre_meta_values.used(),
186 pre_meta_values.committed(),
187 meta_values.used(),
188 meta_values.committed()));
189 }
190 }
191
192 // This will print out a basic metaspace usage report but
193 // unlike print_report() is guaranteed not to lock or to walk the CLDG.
194 void MetaspaceUtils::print_basic_report(outputStream* out, size_t scale) {
195 MetaspaceReporter::print_basic_report(out, scale);
196 }
197
198 // Prints a report about the current metaspace state.
199 // Optional parts can be enabled via flags.
200 // Function will walk the CLDG and will lock the expand lock; if that is not
201 // convenient, use print_basic_report() instead.
202 void MetaspaceUtils::print_report(outputStream* out, size_t scale) {
203 const int flags =
204 (int)MetaspaceReporter::Option::ShowLoaders |
205 (int)MetaspaceReporter::Option::BreakDownByChunkType |
206 (int)MetaspaceReporter::Option::ShowClasses;
207 MetaspaceReporter::print_report(out, scale, flags);
208 }
209
210 void MetaspaceUtils::print_on(outputStream* out) {
211
212 // Used from all GCs. It first prints out totals, then, separately, the class space portion.
213 MetaspaceCombinedStats stats = get_combined_statistics();
214 out->print_cr(" Metaspace "
215 "used " SIZE_FORMAT "K, "
216 "committed " SIZE_FORMAT "K, "
217 "reserved " SIZE_FORMAT "K",
218 stats.used()/K,
219 stats.committed()/K,
220 stats.reserved()/K);
221
222 if (Metaspace::using_class_space()) {
223 out->print_cr(" class space "
224 "used " SIZE_FORMAT "K, "
225 "committed " SIZE_FORMAT "K, "
226 "reserved " SIZE_FORMAT "K",
227 stats.class_space_stats().used()/K,
228 stats.class_space_stats().committed()/K,
229 stats.class_space_stats().reserved()/K);
230 }
231 }
232
233 #ifdef ASSERT
234 void MetaspaceUtils::verify() {
235 if (Metaspace::initialized()) {
236
237 // Verify non-class chunkmanager...
238 ChunkManager* cm = ChunkManager::chunkmanager_nonclass();
239 cm->verify();
240
241 // ... and space list.
242 VirtualSpaceList* vsl = VirtualSpaceList::vslist_nonclass();
243 vsl->verify();
244
245 if (Metaspace::using_class_space()) {
246 // If we use compressed class pointers, verify class chunkmanager...
247 cm = ChunkManager::chunkmanager_class();
248 cm->verify();
249
250 // ... and class spacelist.
251 vsl = VirtualSpaceList::vslist_class();
252 vsl->verify();
253 }
254
255 }
256 }
257 #endif
258
259 ////////////////////////////////7
260 // MetaspaceGC methods
261
262 volatile size_t MetaspaceGC::_capacity_until_GC = 0;
263 uint MetaspaceGC::_shrink_factor = 0;
264
265 // VM_CollectForMetadataAllocation is the vm operation used to GC.
266 // Within the VM operation after the GC the attempt to allocate the metadata
267 // should succeed. If the GC did not free enough space for the metaspace
268 // allocation, the HWM is increased so that another virtualspace will be
269 // allocated for the metadata. With perm gen the increase in the perm
270 // gen had bounds, MinMetaspaceExpansion and MaxMetaspaceExpansion. The
271 // metaspace policy uses those as the small and large steps for the HWM.
272 //
273 // After the GC the compute_new_size() for MetaspaceGC is called to
274 // resize the capacity of the metaspaces. The current implementation
275 // is based on the flags MinMetaspaceFreeRatio and MaxMetaspaceFreeRatio used
276 // to resize the Java heap by some GC's. New flags can be implemented
277 // if really needed. MinMetaspaceFreeRatio is used to calculate how much
278 // free space is desirable in the metaspace capacity to decide how much
279 // to increase the HWM. MaxMetaspaceFreeRatio is used to decide how much
280 // free space is desirable in the metaspace capacity before decreasing
281 // the HWM.
282
283 // Calculate the amount to increase the high water mark (HWM).
284 // Increase by a minimum amount (MinMetaspaceExpansion) so that
285 // another expansion is not requested too soon. If that is not
286 // enough to satisfy the allocation, increase by MaxMetaspaceExpansion.
287 // If that is still not enough, expand by the size of the allocation
288 // plus some.
289 size_t MetaspaceGC::delta_capacity_until_GC(size_t bytes) {
290 size_t min_delta = MinMetaspaceExpansion;
291 size_t max_delta = MaxMetaspaceExpansion;
292 size_t delta = align_up(bytes, Metaspace::commit_alignment());
293
294 if (delta <= min_delta) {
295 delta = min_delta;
296 } else if (delta <= max_delta) {
297 // Don't want to hit the high water mark on the next
298 // allocation so make the delta greater than just enough
299 // for this allocation.
300 delta = max_delta;
301 } else {
302 // This allocation is large but the next ones are probably not
303 // so increase by the minimum.
304 delta = delta + min_delta;
305 }
306
307 assert_is_aligned(delta, Metaspace::commit_alignment());
308
309 return delta;
310 }
311
312 size_t MetaspaceGC::capacity_until_GC() {
313 size_t value = Atomic::load_acquire(&_capacity_until_GC);
314 assert(value >= MetaspaceSize, "Not initialized properly?");
315 return value;
316 }
317
318 // Try to increase the _capacity_until_GC limit counter by v bytes.
319 // Returns true if it succeeded. It may fail if either another thread
320 // concurrently increased the limit or the new limit would be larger
321 // than MaxMetaspaceSize.
322 // On success, optionally returns new and old metaspace capacity in
323 // new_cap_until_GC and old_cap_until_GC respectively.
324 // On error, optionally sets can_retry to indicate whether if there is
325 // actually enough space remaining to satisfy the request.
326 bool MetaspaceGC::inc_capacity_until_GC(size_t v, size_t* new_cap_until_GC, size_t* old_cap_until_GC, bool* can_retry) {
327 assert_is_aligned(v, Metaspace::commit_alignment());
328
329 size_t old_capacity_until_GC = _capacity_until_GC;
330 size_t new_value = old_capacity_until_GC + v;
331
332 if (new_value < old_capacity_until_GC) {
333 // The addition wrapped around, set new_value to aligned max value.
334 new_value = align_down(max_uintx, Metaspace::reserve_alignment());
335 }
336
337 if (new_value > MaxMetaspaceSize) {
338 if (can_retry != nullptr) {
339 *can_retry = false;
340 }
341 return false;
342 }
343
344 if (can_retry != nullptr) {
345 *can_retry = true;
346 }
347 size_t prev_value = Atomic::cmpxchg(&_capacity_until_GC, old_capacity_until_GC, new_value);
348
349 if (old_capacity_until_GC != prev_value) {
350 return false;
351 }
352
353 if (new_cap_until_GC != nullptr) {
354 *new_cap_until_GC = new_value;
355 }
356 if (old_cap_until_GC != nullptr) {
357 *old_cap_until_GC = old_capacity_until_GC;
358 }
359 return true;
360 }
361
362 size_t MetaspaceGC::dec_capacity_until_GC(size_t v) {
363 assert_is_aligned(v, Metaspace::commit_alignment());
364
365 return Atomic::sub(&_capacity_until_GC, v);
366 }
367
368 void MetaspaceGC::initialize() {
369 // Set the high-water mark to MaxMetapaceSize during VM initializaton since
370 // we can't do a GC during initialization.
371 _capacity_until_GC = MaxMetaspaceSize;
372 }
373
374 void MetaspaceGC::post_initialize() {
375 // Reset the high-water mark once the VM initialization is done.
376 _capacity_until_GC = MAX2(MetaspaceUtils::committed_bytes(), MetaspaceSize);
377 }
378
379 bool MetaspaceGC::can_expand(size_t word_size, bool is_class) {
380 // Check if the compressed class space is full.
381 if (is_class && Metaspace::using_class_space()) {
382 size_t class_committed = MetaspaceUtils::committed_bytes(Metaspace::ClassType);
383 if (class_committed + word_size * BytesPerWord > CompressedClassSpaceSize) {
384 log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by " SIZE_FORMAT " words (CompressedClassSpaceSize = " SIZE_FORMAT " words)",
385 (is_class ? "class" : "non-class"), word_size, CompressedClassSpaceSize / sizeof(MetaWord));
386 return false;
387 }
388 }
389
390 // Check if the user has imposed a limit on the metaspace memory.
391 size_t committed_bytes = MetaspaceUtils::committed_bytes();
392 if (committed_bytes + word_size * BytesPerWord > MaxMetaspaceSize) {
393 log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by " SIZE_FORMAT " words (MaxMetaspaceSize = " SIZE_FORMAT " words)",
394 (is_class ? "class" : "non-class"), word_size, MaxMetaspaceSize / sizeof(MetaWord));
395 return false;
396 }
397
398 return true;
399 }
400
401 size_t MetaspaceGC::allowed_expansion() {
402 size_t committed_bytes = MetaspaceUtils::committed_bytes();
403 size_t capacity_until_gc = capacity_until_GC();
404
405 assert(capacity_until_gc >= committed_bytes,
406 "capacity_until_gc: " SIZE_FORMAT " < committed_bytes: " SIZE_FORMAT,
407 capacity_until_gc, committed_bytes);
408
409 size_t left_until_max = MaxMetaspaceSize - committed_bytes;
410 size_t left_until_GC = capacity_until_gc - committed_bytes;
411 size_t left_to_commit = MIN2(left_until_GC, left_until_max);
412 log_trace(gc, metaspace, freelist)("allowed expansion words: " SIZE_FORMAT
413 " (left_until_max: " SIZE_FORMAT ", left_until_GC: " SIZE_FORMAT ".",
414 left_to_commit / BytesPerWord, left_until_max / BytesPerWord, left_until_GC / BytesPerWord);
415
416 return left_to_commit / BytesPerWord;
417 }
418
419 void MetaspaceGC::compute_new_size() {
420 assert(_shrink_factor <= 100, "invalid shrink factor");
421 uint current_shrink_factor = _shrink_factor;
422 _shrink_factor = 0;
423
424 // Using committed_bytes() for used_after_gc is an overestimation, since the
425 // chunk free lists are included in committed_bytes() and the memory in an
426 // un-fragmented chunk free list is available for future allocations.
427 // However, if the chunk free lists becomes fragmented, then the memory may
428 // not be available for future allocations and the memory is therefore "in use".
429 // Including the chunk free lists in the definition of "in use" is therefore
430 // necessary. Not including the chunk free lists can cause capacity_until_GC to
431 // shrink below committed_bytes() and this has caused serious bugs in the past.
432 const size_t used_after_gc = MetaspaceUtils::committed_bytes();
433 const size_t capacity_until_GC = MetaspaceGC::capacity_until_GC();
434
435 const double minimum_free_percentage = MinMetaspaceFreeRatio / 100.0;
436 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
437
438 const double min_tmp = used_after_gc / maximum_used_percentage;
439 size_t minimum_desired_capacity =
440 (size_t)MIN2(min_tmp, double(MaxMetaspaceSize));
441 // Don't shrink less than the initial generation size
442 minimum_desired_capacity = MAX2(minimum_desired_capacity,
443 MetaspaceSize);
444
445 log_trace(gc, metaspace)("MetaspaceGC::compute_new_size: ");
446 log_trace(gc, metaspace)(" minimum_free_percentage: %6.2f maximum_used_percentage: %6.2f",
447 minimum_free_percentage, maximum_used_percentage);
448 log_trace(gc, metaspace)(" used_after_gc : %6.1fKB", used_after_gc / (double) K);
449
450 size_t shrink_bytes = 0;
451 if (capacity_until_GC < minimum_desired_capacity) {
452 // If we have less capacity below the metaspace HWM, then
453 // increment the HWM.
454 size_t expand_bytes = minimum_desired_capacity - capacity_until_GC;
455 expand_bytes = align_up(expand_bytes, Metaspace::commit_alignment());
456 // Don't expand unless it's significant
457 if (expand_bytes >= MinMetaspaceExpansion) {
458 size_t new_capacity_until_GC = 0;
459 bool succeeded = MetaspaceGC::inc_capacity_until_GC(expand_bytes, &new_capacity_until_GC);
460 assert(succeeded, "Should always successfully increment HWM when at safepoint");
461
462 Metaspace::tracer()->report_gc_threshold(capacity_until_GC,
463 new_capacity_until_GC,
464 MetaspaceGCThresholdUpdater::ComputeNewSize);
465 log_trace(gc, metaspace)(" expanding: minimum_desired_capacity: %6.1fKB expand_bytes: %6.1fKB MinMetaspaceExpansion: %6.1fKB new metaspace HWM: %6.1fKB",
466 minimum_desired_capacity / (double) K,
467 expand_bytes / (double) K,
468 MinMetaspaceExpansion / (double) K,
469 new_capacity_until_GC / (double) K);
470 }
471 return;
472 }
473
474 // No expansion, now see if we want to shrink
475 // We would never want to shrink more than this
476 assert(capacity_until_GC >= minimum_desired_capacity,
477 SIZE_FORMAT " >= " SIZE_FORMAT,
478 capacity_until_GC, minimum_desired_capacity);
479 size_t max_shrink_bytes = capacity_until_GC - minimum_desired_capacity;
480
481 // Should shrinking be considered?
482 if (MaxMetaspaceFreeRatio < 100) {
483 const double maximum_free_percentage = MaxMetaspaceFreeRatio / 100.0;
484 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
485 const double max_tmp = used_after_gc / minimum_used_percentage;
486 size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(MaxMetaspaceSize));
487 maximum_desired_capacity = MAX2(maximum_desired_capacity,
488 MetaspaceSize);
489 log_trace(gc, metaspace)(" maximum_free_percentage: %6.2f minimum_used_percentage: %6.2f",
490 maximum_free_percentage, minimum_used_percentage);
491 log_trace(gc, metaspace)(" minimum_desired_capacity: %6.1fKB maximum_desired_capacity: %6.1fKB",
492 minimum_desired_capacity / (double) K, maximum_desired_capacity / (double) K);
493
494 assert(minimum_desired_capacity <= maximum_desired_capacity,
495 "sanity check");
496
497 if (capacity_until_GC > maximum_desired_capacity) {
498 // Capacity too large, compute shrinking size
499 shrink_bytes = capacity_until_GC - maximum_desired_capacity;
500 // We don't want shrink all the way back to initSize if people call
501 // System.gc(), because some programs do that between "phases" and then
502 // we'd just have to grow the heap up again for the next phase. So we
503 // damp the shrinking: 0% on the first call, 10% on the second call, 40%
504 // on the third call, and 100% by the fourth call. But if we recompute
505 // size without shrinking, it goes back to 0%.
506 shrink_bytes = shrink_bytes / 100 * current_shrink_factor;
507
508 shrink_bytes = align_down(shrink_bytes, Metaspace::commit_alignment());
509
510 assert(shrink_bytes <= max_shrink_bytes,
511 "invalid shrink size " SIZE_FORMAT " not <= " SIZE_FORMAT,
512 shrink_bytes, max_shrink_bytes);
513 if (current_shrink_factor == 0) {
514 _shrink_factor = 10;
515 } else {
516 _shrink_factor = MIN2(current_shrink_factor * 4, (uint) 100);
517 }
518 log_trace(gc, metaspace)(" shrinking: initThreshold: %.1fK maximum_desired_capacity: %.1fK",
519 MetaspaceSize / (double) K, maximum_desired_capacity / (double) K);
520 log_trace(gc, metaspace)(" shrink_bytes: %.1fK current_shrink_factor: %d new shrink factor: %d MinMetaspaceExpansion: %.1fK",
521 shrink_bytes / (double) K, current_shrink_factor, _shrink_factor, MinMetaspaceExpansion / (double) K);
522 }
523 }
524
525 // Don't shrink unless it's significant
526 if (shrink_bytes >= MinMetaspaceExpansion &&
527 ((capacity_until_GC - shrink_bytes) >= MetaspaceSize)) {
528 size_t new_capacity_until_GC = MetaspaceGC::dec_capacity_until_GC(shrink_bytes);
529 Metaspace::tracer()->report_gc_threshold(capacity_until_GC,
530 new_capacity_until_GC,
531 MetaspaceGCThresholdUpdater::ComputeNewSize);
532 }
533 }
534
535 ////// Metaspace methods /////
536
537 const MetaspaceTracer* Metaspace::_tracer = nullptr;
538
539 bool Metaspace::initialized() {
540 return metaspace::MetaspaceContext::context_nonclass() != nullptr
541 LP64_ONLY(&& (using_class_space() ? Metaspace::class_space_is_initialized() : true));
542 }
543
544 #ifdef _LP64
545
546 void Metaspace::print_compressed_class_space(outputStream* st) {
547 if (VirtualSpaceList::vslist_class() != nullptr) {
548 MetaWord* base = VirtualSpaceList::vslist_class()->base_of_first_node();
549 size_t size = VirtualSpaceList::vslist_class()->word_size_of_first_node();
550 MetaWord* top = base + size;
551 st->print("Compressed class space mapped at: " PTR_FORMAT "-" PTR_FORMAT ", reserved size: " SIZE_FORMAT,
552 p2i(base), p2i(top), (top - base) * BytesPerWord);
553 st->cr();
554 }
555 }
556
557 // Given a prereserved space, use that to set up the compressed class space list.
558 void Metaspace::initialize_class_space(ReservedSpace rs) {
559 assert(rs.size() >= CompressedClassSpaceSize,
560 SIZE_FORMAT " != " SIZE_FORMAT, rs.size(), CompressedClassSpaceSize);
561 assert(using_class_space(), "Must be using class space");
562
563 assert(rs.size() == CompressedClassSpaceSize, SIZE_FORMAT " != " SIZE_FORMAT,
564 rs.size(), CompressedClassSpaceSize);
565 assert(is_aligned(rs.base(), Metaspace::reserve_alignment()) &&
566 is_aligned(rs.size(), Metaspace::reserve_alignment()),
567 "wrong alignment");
568
569 MetaspaceContext::initialize_class_space_context(rs);
570
571 // This does currently not work because rs may be the result of a split
572 // operation and NMT seems not to be able to handle splits.
573 // Will be fixed with JDK-8243535.
574 // MemTracker::record_virtual_memory_type((address)rs.base(), mtClass);
575
576 }
577
578 // Returns true if class space has been setup (initialize_class_space).
579 bool Metaspace::class_space_is_initialized() {
580 return MetaspaceContext::context_class() != nullptr;
581 }
582
583 // Reserve a range of memory at an address suitable for en/decoding narrow
584 // Klass pointers (see: CompressedClassPointers::is_valid_base()).
585 // The returned address shall both be suitable as a compressed class pointers
586 // base, and aligned to Metaspace::reserve_alignment (which is equal to or a
587 // multiple of allocation granularity).
588 // On error, returns an unreserved space.
589 ReservedSpace Metaspace::reserve_address_space_for_compressed_classes(size_t size) {
590
591 #if defined(AARCH64) || defined(PPC64)
592 const size_t alignment = Metaspace::reserve_alignment();
593
594 // AArch64: Try to align metaspace so that we can decode a compressed
595 // klass with a single MOVK instruction. We can do this iff the
596 // compressed class base is a multiple of 4G.
597 // Additionally, above 32G, ensure the lower LogKlassAlignmentInBytes bits
598 // of the upper 32-bits of the address are zero so we can handle a shift
599 // when decoding.
600
601 // PPC64: smaller heaps up to 2g will be mapped just below 4g. Then the
602 // attempt to place the compressed class space just after the heap fails on
603 // Linux 4.1.42 and higher because the launcher is loaded at 4g
604 // (ELF_ET_DYN_BASE). In that case we reach here and search the address space
605 // below 32g to get a zerobased CCS. For simplicity we reuse the search
606 // strategy for AARCH64.
607
608 static const struct {
609 address from;
610 address to;
611 size_t increment;
612 } search_ranges[] = {
613 { (address)(4*G), (address)(32*G), 4*G, },
614 { (address)(32*G), (address)(1024*G), (4 << LogKlassAlignmentInBytes) * G },
615 { nullptr, nullptr, 0 }
616 };
617
618 for (int i = 0; search_ranges[i].from != nullptr; i ++) {
619 address a = search_ranges[i].from;
620 assert(CompressedKlassPointers::is_valid_base(a), "Sanity");
621 while (a < search_ranges[i].to) {
622 ReservedSpace rs(size, Metaspace::reserve_alignment(),
623 os::vm_page_size(), (char*)a);
624 if (rs.is_reserved()) {
625 assert(a == (address)rs.base(), "Sanity");
626 return rs;
627 }
628 a += search_ranges[i].increment;
629 }
630 }
631 #endif // defined(AARCH64) || defined(PPC64)
632
633 #ifdef AARCH64
634 // Note: on AARCH64, if the code above does not find any good placement, we
635 // have no recourse. We return an empty space and the VM will exit.
636 return ReservedSpace();
637 #else
638 // Default implementation: Just reserve anywhere.
639 return ReservedSpace(size, Metaspace::reserve_alignment(), os::vm_page_size(), (char*)nullptr);
640 #endif // AARCH64
641 }
642
643 #endif // _LP64
644
645 size_t Metaspace::reserve_alignment_words() {
646 return metaspace::Settings::virtual_space_node_reserve_alignment_words();
647 }
648
649 size_t Metaspace::commit_alignment_words() {
650 return metaspace::Settings::commit_granule_words();
651 }
652
653 void Metaspace::ergo_initialize() {
654
655 // Must happen before using any setting from Settings::---
656 metaspace::Settings::ergo_initialize();
657
658 // MaxMetaspaceSize and CompressedClassSpaceSize:
659 //
660 // MaxMetaspaceSize is the maximum size, in bytes, of memory we are allowed
661 // to commit for the Metaspace.
662 // It is just a number; a limit we compare against before committing. It
663 // does not have to be aligned to anything.
664 // It gets used as compare value before attempting to increase the metaspace
665 // commit charge. It defaults to max_uintx (unlimited).
666 //
667 // CompressedClassSpaceSize is the size, in bytes, of the address range we
668 // pre-reserve for the compressed class space (if we use class space).
669 // This size has to be aligned to the metaspace reserve alignment (to the
670 // size of a root chunk). It gets aligned up from whatever value the caller
671 // gave us to the next multiple of root chunk size.
672 //
673 // Note: Strictly speaking MaxMetaspaceSize and CompressedClassSpaceSize have
674 // very little to do with each other. The notion often encountered:
675 // MaxMetaspaceSize = CompressedClassSpaceSize + <non-class metadata size>
676 // is subtly wrong: MaxMetaspaceSize can besmaller than CompressedClassSpaceSize,
677 // in which case we just would not be able to fully commit the class space range.
678 //
679 // We still adjust CompressedClassSpaceSize to reasonable limits, mainly to
680 // save on reserved space, and to make ergnonomics less confusing.
681
682 MaxMetaspaceSize = MAX2(MaxMetaspaceSize, commit_alignment());
683
684 if (UseCompressedClassPointers) {
685 // Let CCS size not be larger than 80% of MaxMetaspaceSize. Note that is
686 // grossly over-dimensioned for most usage scenarios; typical ratio of
687 // class space : non class space usage is about 1:6. With many small classes,
688 // it can get as low as 1:2. It is not a big deal though since ccs is only
689 // reserved and will be committed on demand only.
690 size_t max_ccs_size = MaxMetaspaceSize * 0.8;
691 size_t adjusted_ccs_size = MIN2(CompressedClassSpaceSize, max_ccs_size);
692
693 // CCS must be aligned to root chunk size, and be at least the size of one
694 // root chunk.
695 adjusted_ccs_size = align_up(adjusted_ccs_size, reserve_alignment());
696 adjusted_ccs_size = MAX2(adjusted_ccs_size, reserve_alignment());
697
698 // Note: re-adjusting may have us left with a CompressedClassSpaceSize
699 // larger than MaxMetaspaceSize for very small values of MaxMetaspaceSize.
700 // Lets just live with that, its not a big deal.
701
702 if (adjusted_ccs_size != CompressedClassSpaceSize) {
703 FLAG_SET_ERGO(CompressedClassSpaceSize, adjusted_ccs_size);
704 log_info(metaspace)("Setting CompressedClassSpaceSize to " SIZE_FORMAT ".",
705 CompressedClassSpaceSize);
706 }
707 }
708
709 // Set MetaspaceSize, MinMetaspaceExpansion and MaxMetaspaceExpansion
710 if (MetaspaceSize > MaxMetaspaceSize) {
711 MetaspaceSize = MaxMetaspaceSize;
712 }
713
714 MetaspaceSize = align_down_bounded(MetaspaceSize, commit_alignment());
715
716 assert(MetaspaceSize <= MaxMetaspaceSize, "MetaspaceSize should be limited by MaxMetaspaceSize");
717
718 MinMetaspaceExpansion = align_down_bounded(MinMetaspaceExpansion, commit_alignment());
719 MaxMetaspaceExpansion = align_down_bounded(MaxMetaspaceExpansion, commit_alignment());
720
721 }
722
723 void Metaspace::global_initialize() {
724 MetaspaceGC::initialize(); // <- since we do not prealloc init chunks anymore is this still needed?
725
726 metaspace::ChunkHeaderPool::initialize();
727
728 if (DumpSharedSpaces) {
729 assert(!UseSharedSpaces, "sanity");
730 MetaspaceShared::initialize_for_static_dump();
731 }
732
733 // If UseCompressedClassPointers=1, we have two cases:
734 // a) if CDS is active (runtime, Xshare=on), it will create the class space
735 // for us, initialize it and set up CompressedKlassPointers encoding.
736 // Class space will be reserved above the mapped archives.
737 // b) if CDS either deactivated (Xshare=off) or a static dump is to be done (Xshare:dump),
738 // we will create the class space on our own. It will be placed above the java heap,
739 // since we assume it has been placed in low
740 // address regions. We may rethink this (see JDK-8244943). Failing that,
741 // it will be placed anywhere.
742
743 #if INCLUDE_CDS
744 // case (a)
745 if (UseSharedSpaces) {
746 if (!FLAG_IS_DEFAULT(CompressedClassSpaceBaseAddress)) {
747 log_warning(metaspace)("CDS active - ignoring CompressedClassSpaceBaseAddress.");
748 }
749 MetaspaceShared::initialize_runtime_shared_and_meta_spaces();
750 // If any of the archived space fails to map, UseSharedSpaces
751 // is reset to false.
752 }
753 #endif // INCLUDE_CDS
754
755 #ifdef _LP64
756
757 if (using_class_space() && !class_space_is_initialized()) {
758 assert(!UseSharedSpaces, "CDS archive is not mapped at this point");
759
760 // case (b) (No CDS)
761 ReservedSpace rs;
762 const size_t size = align_up(CompressedClassSpaceSize, Metaspace::reserve_alignment());
763 address base = nullptr;
764
765 // If CompressedClassSpaceBaseAddress is set, we attempt to force-map class space to
766 // the given address. This is a debug-only feature aiding tests. Due to the ASLR lottery
767 // this may fail, in which case the VM will exit after printing an appropriate message.
768 // Tests using this switch should cope with that.
769 if (CompressedClassSpaceBaseAddress != 0) {
770 base = (address)CompressedClassSpaceBaseAddress;
771 if (!is_aligned(base, Metaspace::reserve_alignment())) {
772 vm_exit_during_initialization(
773 err_msg("CompressedClassSpaceBaseAddress=" PTR_FORMAT " invalid "
774 "(must be aligned to " SIZE_FORMAT_X ").",
775 CompressedClassSpaceBaseAddress, Metaspace::reserve_alignment()));
776 }
777 rs = ReservedSpace(size, Metaspace::reserve_alignment(),
778 os::vm_page_size() /* large */, (char*)base);
779 if (rs.is_reserved()) {
780 log_info(metaspace)("Successfully forced class space address to " PTR_FORMAT, p2i(base));
781 } else {
782 vm_exit_during_initialization(
783 err_msg("CompressedClassSpaceBaseAddress=" PTR_FORMAT " given, but reserving class space failed.",
784 CompressedClassSpaceBaseAddress));
785 }
786 }
787
788 if (!rs.is_reserved()) {
789 // If UseCompressedOops=1 and the java heap has been placed in coops-friendly
790 // territory, i.e. its base is under 32G, then we attempt to place ccs
791 // right above the java heap.
792 // Otherwise the lower 32G are still free. We try to place ccs at the lowest
793 // allowed mapping address.
794 base = (UseCompressedOops && (uint64_t)CompressedOops::base() < OopEncodingHeapMax) ?
795 CompressedOops::end() : (address)HeapBaseMinAddress;
796 base = align_up(base, Metaspace::reserve_alignment());
797
798 if (base != nullptr) {
799 if (CompressedKlassPointers::is_valid_base(base)) {
800 rs = ReservedSpace(size, Metaspace::reserve_alignment(),
801 os::vm_page_size(), (char*)base);
802 }
803 }
804 }
805
806 // ...failing that, reserve anywhere, but let platform do optimized placement:
807 if (!rs.is_reserved()) {
808 rs = Metaspace::reserve_address_space_for_compressed_classes(size);
809 }
810
811 // ...failing that, give up.
812 if (!rs.is_reserved()) {
813 vm_exit_during_initialization(
814 err_msg("Could not allocate compressed class space: " SIZE_FORMAT " bytes",
815 CompressedClassSpaceSize));
816 }
817
818 // Initialize space
819 Metaspace::initialize_class_space(rs);
820
821 // Set up compressed class pointer encoding.
822 CompressedKlassPointers::initialize((address)rs.base(), rs.size());
823 }
824
825 #endif
826
827 // Initialize non-class virtual space list, and its chunk manager:
828 MetaspaceContext::initialize_nonclass_space_context();
829
830 _tracer = new MetaspaceTracer();
831
832 // We must prevent the very first address of the ccs from being used to store
833 // metadata, since that address would translate to a narrow pointer of 0, and the
834 // VM does not distinguish between "narrow 0 as in null" and "narrow 0 as in start
835 // of ccs".
836 // Before Elastic Metaspace that did not happen due to the fact that every Metachunk
837 // had a header and therefore could not allocate anything at offset 0.
838 #ifdef _LP64
839 if (using_class_space()) {
840 // The simplest way to fix this is to allocate a tiny dummy chunk right at the
841 // start of ccs and do not use it for anything.
842 MetaspaceContext::context_class()->cm()->get_chunk(metaspace::chunklevel::HIGHEST_CHUNK_LEVEL);
843 }
844 #endif
845
846 #ifdef _LP64
847 if (UseCompressedClassPointers) {
848 // Note: "cds" would be a better fit but keep this for backward compatibility.
849 LogTarget(Info, gc, metaspace) lt;
850 if (lt.is_enabled()) {
851 ResourceMark rm;
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) {
875 assert(word_size <= Metaspace::max_allocation_word_size(),
876 "allocation size too large (" SIZE_FORMAT ")", word_size);
877
878 assert(loader_data != nullptr, "Should never pass around a nullptr 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 = (type == MetaspaceObj::ClassType) ? 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 // Zero initialize.
891 Copy::fill_to_words((HeapWord*)result, word_size, 0);
892
893 log_trace(metaspace)("Metaspace::allocate: type %d return " PTR_FORMAT ".", (int)type, p2i(result));
894 }
895
896 return result;
897 }
898
899 MetaWord* Metaspace::allocate(ClassLoaderData* loader_data, size_t word_size,
900 MetaspaceObj::Type type, TRAPS) {
901
902 if (HAS_PENDING_EXCEPTION) {
903 assert(false, "Should not allocate with exception pending");
904 return nullptr; // caller does a CHECK_NULL too
905 }
906
907 MetaWord* result = allocate(loader_data, word_size, type);
908
909 if (result == nullptr) {
910 MetadataType mdtype = (type == MetaspaceObj::ClassType) ? ClassType : NonClassType;
911 tracer()->report_metaspace_allocation_failure(loader_data, word_size, type, mdtype);
912
913 // Allocation failed.
914 if (is_init_completed()) {
915 // Only start a GC if the bootstrapping has completed.
916 // Try to clean out some heap memory and retry. This can prevent premature
917 // expansion of the metaspace.
918 result = Universe::heap()->satisfy_failed_metadata_allocation(loader_data, word_size, mdtype);
919 }
920
921 if (result == nullptr) {
922 report_metadata_oome(loader_data, word_size, type, mdtype, THREAD);
923 assert(HAS_PENDING_EXCEPTION, "sanity");
924 return nullptr;
925 }
926
927 // Zero initialize.
928 Copy::fill_to_words((HeapWord*)result, word_size, 0);
929
930 log_trace(metaspace)("Metaspace::allocate: type %d return " PTR_FORMAT ".", (int)type, p2i(result));
931 }
932
933 return result;
934 }
935
936 void Metaspace::report_metadata_oome(ClassLoaderData* loader_data, size_t word_size, MetaspaceObj::Type type, MetadataType mdtype, TRAPS) {
937 tracer()->report_metadata_oom(loader_data, word_size, type, mdtype);
938
939 // If result is still null, we are out of memory.
940 Log(gc, metaspace, freelist, oom) log;
941 if (log.is_info()) {
942 log.info("Metaspace (%s) allocation failed for size " SIZE_FORMAT,
943 is_class_space_allocation(mdtype) ? "class" : "data", word_size);
944 ResourceMark rm;
945 if (log.is_debug()) {
946 if (loader_data->metaspace_or_null() != nullptr) {
947 LogStream ls(log.debug());
948 loader_data->print_value_on(&ls);
949 }
950 }
951 LogStream ls(log.info());
952 // In case of an OOM, log out a short but still useful report.
953 MetaspaceUtils::print_basic_report(&ls, 0);
954 }
955
956 bool out_of_compressed_class_space = false;
957 if (is_class_space_allocation(mdtype)) {
958 ClassLoaderMetaspace* metaspace = loader_data->metaspace_non_null();
959 out_of_compressed_class_space =
960 MetaspaceUtils::committed_bytes(Metaspace::ClassType) +
961 align_up(word_size * BytesPerWord, 4 * M) >
962 CompressedClassSpaceSize;
963 }
964
965 // -XX:+HeapDumpOnOutOfMemoryError and -XX:OnOutOfMemoryError support
966 const char* space_string = out_of_compressed_class_space ?
967 "Compressed class space" : "Metaspace";
968
969 report_java_out_of_memory(space_string);
970
971 if (JvmtiExport::should_post_resource_exhausted()) {
972 JvmtiExport::post_resource_exhausted(
973 JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR,
974 space_string);
975 }
976
977 if (!is_init_completed()) {
978 vm_exit_during_initialization("OutOfMemoryError", space_string);
979 }
980
981 if (out_of_compressed_class_space) {
982 THROW_OOP(Universe::out_of_memory_error_class_metaspace());
983 } else {
984 THROW_OOP(Universe::out_of_memory_error_metaspace());
985 }
986 }
987
988 const char* Metaspace::metadata_type_name(Metaspace::MetadataType mdtype) {
989 switch (mdtype) {
990 case Metaspace::ClassType: return "Class";
991 case Metaspace::NonClassType: return "Metadata";
992 default:
993 assert(false, "Got bad mdtype: %d", (int) mdtype);
994 return nullptr;
995 }
996 }
997
998 void Metaspace::purge(bool classes_unloaded) {
999 // The MetaspaceCritical_lock is used by a concurrent GC to block out concurrent metaspace
1000 // allocations, that would starve critical metaspace allocations, that are about to throw
1001 // OOM if they fail; they need precedence for correctness.
1002 MutexLocker ml(MetaspaceCritical_lock, Mutex::_no_safepoint_check_flag);
1003 if (classes_unloaded) {
1004 ChunkManager* cm = ChunkManager::chunkmanager_nonclass();
1005 if (cm != nullptr) {
1006 cm->purge();
1007 }
1008 if (using_class_space()) {
1009 cm = ChunkManager::chunkmanager_class();
1010 if (cm != nullptr) {
1011 cm->purge();
1012 }
1013 }
1014 }
1015
1016 // Try to satisfy queued metaspace allocation requests.
1017 //
1018 // It might seem unnecessary to try to process allocation requests if no
1019 // classes have been unloaded. However, this call is required for the code
1020 // in MetaspaceCriticalAllocation::try_allocate_critical to work.
1021 MetaspaceCriticalAllocation::process();
1022 }
1023
1024 bool Metaspace::contains(const void* ptr) {
1025 if (MetaspaceShared::is_in_shared_metaspace(ptr)) {
1026 return true;
1027 }
1028 return contains_non_shared(ptr);
1029 }
1030
1031 bool Metaspace::contains_non_shared(const void* ptr) {
1032 if (using_class_space() && VirtualSpaceList::vslist_class()->contains((MetaWord*)ptr)) {
1033 return true;
1034 }
1035
1036 return VirtualSpaceList::vslist_nonclass()->contains((MetaWord*)ptr);
1037 }