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/metaspaceAlignment.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/metaspaceTracer.hpp"
47 #include "memory/metaspaceStats.hpp"
48 #include "memory/metaspaceUtils.hpp"
49 #include "memory/resourceArea.hpp"
50 #include "memory/universe.hpp"
51 #include "oops/compressedOops.hpp"
52 #include "prims/jvmtiExport.hpp"
53 #include "runtime/atomic.hpp"
54 #include "runtime/globals_extension.hpp"
55 #include "runtime/init.hpp"
56 #include "runtime/java.hpp"
57 #include "services/memTracker.hpp"
58 #include "utilities/copy.hpp"
59 #include "utilities/debug.hpp"
60 #include "utilities/formatBuffer.hpp"
61 #include "utilities/globalDefinitions.hpp"
62
63 using metaspace::ChunkManager;
64 using metaspace::CommitLimiter;
65 using metaspace::MetaspaceContext;
66 using metaspace::MetaspaceReporter;
67 using metaspace::RunningCounters;
68 using metaspace::VirtualSpaceList;
69
70 size_t MetaspaceUtils::used_words() {
71 return RunningCounters::used_words();
72 }
73
74 size_t MetaspaceUtils::used_words(Metaspace::MetadataType mdtype) {
75 return mdtype == Metaspace::ClassType ? RunningCounters::used_words_class() : RunningCounters::used_words_nonclass();
76 }
77
78 size_t MetaspaceUtils::reserved_words() {
79 return RunningCounters::reserved_words();
80 }
81
82 size_t MetaspaceUtils::reserved_words(Metaspace::MetadataType mdtype) {
83 return mdtype == Metaspace::ClassType ? RunningCounters::reserved_words_class() : RunningCounters::reserved_words_nonclass();
84 }
85
86 size_t MetaspaceUtils::committed_words() {
87 return RunningCounters::committed_words();
88 }
89
90 size_t MetaspaceUtils::committed_words(Metaspace::MetadataType mdtype) {
91 return mdtype == Metaspace::ClassType ? RunningCounters::committed_words_class() : RunningCounters::committed_words_nonclass();
92 }
93
94 // Helper for get_statistics()
95 static void get_values_for(Metaspace::MetadataType mdtype, size_t* reserved, size_t* committed, size_t* used) {
96 #define w2b(x) (x * sizeof(MetaWord))
97 if (mdtype == Metaspace::ClassType) {
98 *reserved = w2b(RunningCounters::reserved_words_class());
99 *committed = w2b(RunningCounters::committed_words_class());
100 *used = w2b(RunningCounters::used_words_class());
101 } else {
102 *reserved = w2b(RunningCounters::reserved_words_nonclass());
103 *committed = w2b(RunningCounters::committed_words_nonclass());
104 *used = w2b(RunningCounters::used_words_nonclass());
105 }
106 #undef w2b
107 }
108
109 // Retrieve all statistics in one go; make sure the values are consistent.
110 MetaspaceStats MetaspaceUtils::get_statistics(Metaspace::MetadataType mdtype) {
111
112 // Consistency:
113 // This function reads three values (reserved, committed, used) from different counters. These counters
114 // may (very rarely) be out of sync. This has been a source for intermittent test errors in the past
115 // (see e.g. JDK-8237872, JDK-8151460).
116 // - reserved and committed counter are updated under protection of Metaspace_lock; an inconsistency
117 // between them can be the result of a dirty read.
118 // - used is an atomic counter updated outside any lock range; there is no way to guarantee
119 // a clean read wrt the other two values.
120 // Reading these values under lock protection would would only help for the first case. Therefore
121 // we don't bother and just re-read several times, then give up and correct the values.
122
123 size_t r = 0, c = 0, u = 0; // Note: byte values.
124 get_values_for(mdtype, &r, &c, &u);
125 int retries = 10;
126 // If the first retrieval resulted in inconsistent values, retry a bit...
127 while ((r < c || c < u) && --retries >= 0) {
128 get_values_for(mdtype, &r, &c, &u);
129 }
130 if (c < u || r < c) { // still inconsistent.
131 // ... but not endlessly. If we don't get consistent values, correct them on the fly.
132 // The logic here is that we trust the used counter - its an atomic counter and whatever we see
133 // must have been the truth once - and from that we reconstruct a likely set of committed/reserved
134 // values.
135 metaspace::InternalStats::inc_num_inconsistent_stats();
136 if (c < u) {
137 c = align_up(u, Metaspace::commit_alignment());
138 }
139 if (r < c) {
140 r = align_up(c, Metaspace::reserve_alignment());
141 }
142 }
143 return MetaspaceStats(r, c, u);
144 }
145
146 MetaspaceCombinedStats MetaspaceUtils::get_combined_statistics() {
147 return MetaspaceCombinedStats(get_statistics(Metaspace::ClassType), get_statistics(Metaspace::NonClassType));
148 }
149
150 void MetaspaceUtils::print_metaspace_change(const MetaspaceCombinedStats& pre_meta_values) {
151 // Get values now:
152 const MetaspaceCombinedStats meta_values = get_combined_statistics();
153
154 // We print used and committed since these are the most useful at-a-glance vitals for Metaspace:
155 // - used tells you how much memory is actually used for metadata
156 // - committed tells you how much memory is committed for the purpose of metadata
157 // The difference between those two would be waste, which can have various forms (freelists,
158 // unused parts of committed chunks etc)
159 //
160 // Left out is reserved, since this is not as exciting as the first two values: for class space,
161 // it is a constant (to uninformed users, often confusingly large). For non-class space, it would
162 // be interesting since free chunks can be uncommitted, but for now it is left out.
163
164 if (Metaspace::using_class_space()) {
165 log_info(gc, metaspace)(HEAP_CHANGE_FORMAT" "
166 HEAP_CHANGE_FORMAT" "
167 HEAP_CHANGE_FORMAT,
168 HEAP_CHANGE_FORMAT_ARGS("Metaspace",
169 pre_meta_values.used(),
170 pre_meta_values.committed(),
171 meta_values.used(),
172 meta_values.committed()),
173 HEAP_CHANGE_FORMAT_ARGS("NonClass",
174 pre_meta_values.non_class_used(),
175 pre_meta_values.non_class_committed(),
176 meta_values.non_class_used(),
177 meta_values.non_class_committed()),
178 HEAP_CHANGE_FORMAT_ARGS("Class",
179 pre_meta_values.class_used(),
180 pre_meta_values.class_committed(),
181 meta_values.class_used(),
182 meta_values.class_committed()));
183 } else {
184 log_info(gc, metaspace)(HEAP_CHANGE_FORMAT,
185 HEAP_CHANGE_FORMAT_ARGS("Metaspace",
186 pre_meta_values.used(),
187 pre_meta_values.committed(),
188 meta_values.used(),
189 meta_values.committed()));
190 }
191 }
192
193 // This will print out a basic metaspace usage report but
194 // unlike print_report() is guaranteed not to lock or to walk the CLDG.
195 void MetaspaceUtils::print_basic_report(outputStream* out, size_t scale) {
196 MetaspaceReporter::print_basic_report(out, scale);
197 }
198
199 // Prints a report about the current metaspace state.
200 // Optional parts can be enabled via flags.
201 // Function will walk the CLDG and will lock the expand lock; if that is not
202 // convenient, use print_basic_report() instead.
203 void MetaspaceUtils::print_report(outputStream* out, size_t scale) {
204 const int flags =
205 (int)MetaspaceReporter::Option::ShowLoaders |
206 (int)MetaspaceReporter::Option::BreakDownByChunkType |
207 (int)MetaspaceReporter::Option::ShowClasses;
208 MetaspaceReporter::print_report(out, scale, flags);
209 }
210
211 void MetaspaceUtils::print_on(outputStream* out) {
212
213 // Used from all GCs. It first prints out totals, then, separately, the class space portion.
214 MetaspaceCombinedStats stats = get_combined_statistics();
215 out->print_cr(" Metaspace "
216 "used " SIZE_FORMAT "K, "
217 "committed " SIZE_FORMAT "K, "
218 "reserved " SIZE_FORMAT "K",
219 stats.used()/K,
220 stats.committed()/K,
221 stats.reserved()/K);
222
223 if (Metaspace::using_class_space()) {
224 out->print_cr(" class space "
225 "used " SIZE_FORMAT "K, "
226 "committed " SIZE_FORMAT "K, "
227 "reserved " SIZE_FORMAT "K",
228 stats.class_space_stats().used()/K,
229 stats.class_space_stats().committed()/K,
230 stats.class_space_stats().reserved()/K);
231 }
232 }
233
234 #ifdef ASSERT
235 void MetaspaceUtils::verify() {
236 if (Metaspace::initialized()) {
237
238 // Verify non-class chunkmanager...
239 ChunkManager* cm = ChunkManager::chunkmanager_nonclass();
240 cm->verify();
241
242 // ... and space list.
243 VirtualSpaceList* vsl = VirtualSpaceList::vslist_nonclass();
244 vsl->verify();
245
246 if (Metaspace::using_class_space()) {
247 // If we use compressed class pointers, verify class chunkmanager...
248 cm = ChunkManager::chunkmanager_class();
249 cm->verify();
250
251 // ... and class spacelist.
252 vsl = VirtualSpaceList::vslist_class();
253 vsl->verify();
254 }
255
256 }
257 }
258 #endif
259
260 ////////////////////////////////7
261 // MetaspaceGC methods
262
263 volatile size_t MetaspaceGC::_capacity_until_GC = 0;
264 uint MetaspaceGC::_shrink_factor = 0;
265
266 // VM_CollectForMetadataAllocation is the vm operation used to GC.
267 // Within the VM operation after the GC the attempt to allocate the metadata
268 // should succeed. If the GC did not free enough space for the metaspace
269 // allocation, the HWM is increased so that another virtualspace will be
270 // allocated for the metadata. With perm gen the increase in the perm
271 // gen had bounds, MinMetaspaceExpansion and MaxMetaspaceExpansion. The
272 // metaspace policy uses those as the small and large steps for the HWM.
273 //
274 // After the GC the compute_new_size() for MetaspaceGC is called to
275 // resize the capacity of the metaspaces. The current implementation
276 // is based on the flags MinMetaspaceFreeRatio and MaxMetaspaceFreeRatio used
277 // to resize the Java heap by some GC's. New flags can be implemented
278 // if really needed. MinMetaspaceFreeRatio is used to calculate how much
279 // free space is desirable in the metaspace capacity to decide how much
280 // to increase the HWM. MaxMetaspaceFreeRatio is used to decide how much
281 // free space is desirable in the metaspace capacity before decreasing
282 // the HWM.
283
284 // Calculate the amount to increase the high water mark (HWM).
285 // Increase by a minimum amount (MinMetaspaceExpansion) so that
286 // another expansion is not requested too soon. If that is not
287 // enough to satisfy the allocation, increase by MaxMetaspaceExpansion.
288 // If that is still not enough, expand by the size of the allocation
289 // plus some.
290 size_t MetaspaceGC::delta_capacity_until_GC(size_t bytes) {
291 size_t min_delta = MinMetaspaceExpansion;
292 size_t max_delta = MaxMetaspaceExpansion;
293 size_t delta = align_up(bytes, Metaspace::commit_alignment());
294
295 if (delta <= min_delta) {
296 delta = min_delta;
297 } else if (delta <= max_delta) {
298 // Don't want to hit the high water mark on the next
299 // allocation so make the delta greater than just enough
300 // for this allocation.
301 delta = max_delta;
302 } else {
303 // This allocation is large but the next ones are probably not
304 // so increase by the minimum.
305 delta = delta + min_delta;
306 }
307
308 assert_is_aligned(delta, Metaspace::commit_alignment());
309
310 return delta;
311 }
312
313 size_t MetaspaceGC::capacity_until_GC() {
314 size_t value = Atomic::load_acquire(&_capacity_until_GC);
315 assert(value >= MetaspaceSize, "Not initialized properly?");
316 return value;
317 }
318
319 // Try to increase the _capacity_until_GC limit counter by v bytes.
320 // Returns true if it succeeded. It may fail if either another thread
321 // concurrently increased the limit or the new limit would be larger
322 // than MaxMetaspaceSize.
323 // On success, optionally returns new and old metaspace capacity in
324 // new_cap_until_GC and old_cap_until_GC respectively.
325 // On error, optionally sets can_retry to indicate whether if there is
326 // actually enough space remaining to satisfy the request.
327 bool MetaspaceGC::inc_capacity_until_GC(size_t v, size_t* new_cap_until_GC, size_t* old_cap_until_GC, bool* can_retry) {
328 assert_is_aligned(v, Metaspace::commit_alignment());
329
330 size_t old_capacity_until_GC = _capacity_until_GC;
331 size_t new_value = old_capacity_until_GC + v;
332
333 if (new_value < old_capacity_until_GC) {
334 // The addition wrapped around, set new_value to aligned max value.
335 new_value = align_down(max_uintx, Metaspace::reserve_alignment());
336 }
337
338 if (new_value > MaxMetaspaceSize) {
339 if (can_retry != nullptr) {
340 *can_retry = false;
341 }
342 return false;
343 }
344
345 if (can_retry != nullptr) {
346 *can_retry = true;
347 }
348 size_t prev_value = Atomic::cmpxchg(&_capacity_until_GC, old_capacity_until_GC, new_value);
349
350 if (old_capacity_until_GC != prev_value) {
351 return false;
352 }
353
354 if (new_cap_until_GC != nullptr) {
355 *new_cap_until_GC = new_value;
356 }
357 if (old_cap_until_GC != nullptr) {
358 *old_cap_until_GC = old_capacity_until_GC;
359 }
360 return true;
361 }
362
363 size_t MetaspaceGC::dec_capacity_until_GC(size_t v) {
364 assert_is_aligned(v, Metaspace::commit_alignment());
365
366 return Atomic::sub(&_capacity_until_GC, v);
367 }
368
369 void MetaspaceGC::initialize() {
370 // Set the high-water mark to MaxMetapaceSize during VM initializaton since
371 // we can't do a GC during initialization.
372 _capacity_until_GC = MaxMetaspaceSize;
373 }
374
375 void MetaspaceGC::post_initialize() {
376 // Reset the high-water mark once the VM initialization is done.
377 _capacity_until_GC = MAX2(MetaspaceUtils::committed_bytes(), MetaspaceSize);
378 }
379
380 bool MetaspaceGC::can_expand(size_t word_size, bool is_class) {
381 // Check if the compressed class space is full.
382 if (is_class && Metaspace::using_class_space()) {
383 size_t class_committed = MetaspaceUtils::committed_bytes(Metaspace::ClassType);
384 if (class_committed + word_size * BytesPerWord > CompressedClassSpaceSize) {
385 log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by " SIZE_FORMAT " words (CompressedClassSpaceSize = " SIZE_FORMAT " words)",
386 (is_class ? "class" : "non-class"), word_size, CompressedClassSpaceSize / sizeof(MetaWord));
387 return false;
388 }
389 }
390
391 // Check if the user has imposed a limit on the metaspace memory.
392 size_t committed_bytes = MetaspaceUtils::committed_bytes();
393 if (committed_bytes + word_size * BytesPerWord > MaxMetaspaceSize) {
394 log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by " SIZE_FORMAT " words (MaxMetaspaceSize = " SIZE_FORMAT " words)",
395 (is_class ? "class" : "non-class"), word_size, MaxMetaspaceSize / sizeof(MetaWord));
396 return false;
397 }
398
399 return true;
400 }
401
402 size_t MetaspaceGC::allowed_expansion() {
403 size_t committed_bytes = MetaspaceUtils::committed_bytes();
404 size_t capacity_until_gc = capacity_until_GC();
405
406 assert(capacity_until_gc >= committed_bytes,
407 "capacity_until_gc: " SIZE_FORMAT " < committed_bytes: " SIZE_FORMAT,
408 capacity_until_gc, committed_bytes);
409
410 size_t left_until_max = MaxMetaspaceSize - committed_bytes;
411 size_t left_until_GC = capacity_until_gc - committed_bytes;
412 size_t left_to_commit = MIN2(left_until_GC, left_until_max);
413 log_trace(gc, metaspace, freelist)("allowed expansion words: " SIZE_FORMAT
414 " (left_until_max: " SIZE_FORMAT ", left_until_GC: " SIZE_FORMAT ".",
415 left_to_commit / BytesPerWord, left_until_max / BytesPerWord, left_until_GC / BytesPerWord);
416
417 return left_to_commit / BytesPerWord;
418 }
419
420 void MetaspaceGC::compute_new_size() {
421 assert(_shrink_factor <= 100, "invalid shrink factor");
422 uint current_shrink_factor = _shrink_factor;
423 _shrink_factor = 0;
424
425 // Using committed_bytes() for used_after_gc is an overestimation, since the
426 // chunk free lists are included in committed_bytes() and the memory in an
427 // un-fragmented chunk free list is available for future allocations.
428 // However, if the chunk free lists becomes fragmented, then the memory may
429 // not be available for future allocations and the memory is therefore "in use".
430 // Including the chunk free lists in the definition of "in use" is therefore
431 // necessary. Not including the chunk free lists can cause capacity_until_GC to
432 // shrink below committed_bytes() and this has caused serious bugs in the past.
433 const size_t used_after_gc = MetaspaceUtils::committed_bytes();
434 const size_t capacity_until_GC = MetaspaceGC::capacity_until_GC();
435
436 const double minimum_free_percentage = MinMetaspaceFreeRatio / 100.0;
437 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
438
439 const double min_tmp = used_after_gc / maximum_used_percentage;
440 size_t minimum_desired_capacity =
441 (size_t)MIN2(min_tmp, double(MaxMetaspaceSize));
442 // Don't shrink less than the initial generation size
443 minimum_desired_capacity = MAX2(minimum_desired_capacity,
444 MetaspaceSize);
445
446 log_trace(gc, metaspace)("MetaspaceGC::compute_new_size: ");
447 log_trace(gc, metaspace)(" minimum_free_percentage: %6.2f maximum_used_percentage: %6.2f",
448 minimum_free_percentage, maximum_used_percentage);
449 log_trace(gc, metaspace)(" used_after_gc : %6.1fKB", used_after_gc / (double) K);
450
451 size_t shrink_bytes = 0;
452 if (capacity_until_GC < minimum_desired_capacity) {
453 // If we have less capacity below the metaspace HWM, then
454 // increment the HWM.
455 size_t expand_bytes = minimum_desired_capacity - capacity_until_GC;
456 expand_bytes = align_up(expand_bytes, Metaspace::commit_alignment());
457 // Don't expand unless it's significant
458 if (expand_bytes >= MinMetaspaceExpansion) {
459 size_t new_capacity_until_GC = 0;
460 bool succeeded = MetaspaceGC::inc_capacity_until_GC(expand_bytes, &new_capacity_until_GC);
461 assert(succeeded, "Should always successfully increment HWM when at safepoint");
462
463 Metaspace::tracer()->report_gc_threshold(capacity_until_GC,
464 new_capacity_until_GC,
465 MetaspaceGCThresholdUpdater::ComputeNewSize);
466 log_trace(gc, metaspace)(" expanding: minimum_desired_capacity: %6.1fKB expand_bytes: %6.1fKB MinMetaspaceExpansion: %6.1fKB new metaspace HWM: %6.1fKB",
467 minimum_desired_capacity / (double) K,
468 expand_bytes / (double) K,
469 MinMetaspaceExpansion / (double) K,
470 new_capacity_until_GC / (double) K);
471 }
472 return;
473 }
474
475 // No expansion, now see if we want to shrink
476 // We would never want to shrink more than this
477 assert(capacity_until_GC >= minimum_desired_capacity,
478 SIZE_FORMAT " >= " SIZE_FORMAT,
479 capacity_until_GC, minimum_desired_capacity);
480 size_t max_shrink_bytes = capacity_until_GC - minimum_desired_capacity;
481
482 // Should shrinking be considered?
483 if (MaxMetaspaceFreeRatio < 100) {
484 const double maximum_free_percentage = MaxMetaspaceFreeRatio / 100.0;
485 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
486 const double max_tmp = used_after_gc / minimum_used_percentage;
487 size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(MaxMetaspaceSize));
488 maximum_desired_capacity = MAX2(maximum_desired_capacity,
489 MetaspaceSize);
490 log_trace(gc, metaspace)(" maximum_free_percentage: %6.2f minimum_used_percentage: %6.2f",
491 maximum_free_percentage, minimum_used_percentage);
492 log_trace(gc, metaspace)(" minimum_desired_capacity: %6.1fKB maximum_desired_capacity: %6.1fKB",
493 minimum_desired_capacity / (double) K, maximum_desired_capacity / (double) K);
494
495 assert(minimum_desired_capacity <= maximum_desired_capacity,
496 "sanity check");
497
498 if (capacity_until_GC > maximum_desired_capacity) {
499 // Capacity too large, compute shrinking size
500 shrink_bytes = capacity_until_GC - maximum_desired_capacity;
501 // We don't want shrink all the way back to initSize if people call
502 // System.gc(), because some programs do that between "phases" and then
503 // we'd just have to grow the heap up again for the next phase. So we
504 // damp the shrinking: 0% on the first call, 10% on the second call, 40%
505 // on the third call, and 100% by the fourth call. But if we recompute
506 // size without shrinking, it goes back to 0%.
507 shrink_bytes = shrink_bytes / 100 * current_shrink_factor;
508
509 shrink_bytes = align_down(shrink_bytes, Metaspace::commit_alignment());
510
511 assert(shrink_bytes <= max_shrink_bytes,
512 "invalid shrink size " SIZE_FORMAT " not <= " SIZE_FORMAT,
513 shrink_bytes, max_shrink_bytes);
514 if (current_shrink_factor == 0) {
515 _shrink_factor = 10;
516 } else {
517 _shrink_factor = MIN2(current_shrink_factor * 4, (uint) 100);
518 }
519 log_trace(gc, metaspace)(" shrinking: initThreshold: %.1fK maximum_desired_capacity: %.1fK",
520 MetaspaceSize / (double) K, maximum_desired_capacity / (double) K);
521 log_trace(gc, metaspace)(" shrink_bytes: %.1fK current_shrink_factor: %d new shrink factor: %d MinMetaspaceExpansion: %.1fK",
522 shrink_bytes / (double) K, current_shrink_factor, _shrink_factor, MinMetaspaceExpansion / (double) K);
523 }
524 }
525
526 // Don't shrink unless it's significant
527 if (shrink_bytes >= MinMetaspaceExpansion &&
528 ((capacity_until_GC - shrink_bytes) >= MetaspaceSize)) {
529 size_t new_capacity_until_GC = MetaspaceGC::dec_capacity_until_GC(shrink_bytes);
530 Metaspace::tracer()->report_gc_threshold(capacity_until_GC,
531 new_capacity_until_GC,
532 MetaspaceGCThresholdUpdater::ComputeNewSize);
533 }
534 }
535
536 ////// Metaspace methods /////
537
538 const MetaspaceTracer* Metaspace::_tracer = nullptr;
539
540 bool Metaspace::initialized() {
541 return metaspace::MetaspaceContext::context_nonclass() != nullptr
542 LP64_ONLY(&& (using_class_space() ? Metaspace::class_space_is_initialized() : true));
543 }
544
545 #ifdef _LP64
546
547 void Metaspace::print_compressed_class_space(outputStream* st) {
548 if (VirtualSpaceList::vslist_class() != nullptr) {
549 MetaWord* base = VirtualSpaceList::vslist_class()->base_of_first_node();
550 size_t size = VirtualSpaceList::vslist_class()->word_size_of_first_node();
551 MetaWord* top = base + size;
552 st->print("Compressed class space mapped at: " PTR_FORMAT "-" PTR_FORMAT ", reserved size: " SIZE_FORMAT,
553 p2i(base), p2i(top), (top - base) * BytesPerWord);
554 st->cr();
555 }
556 }
557
558 // Given a prereserved space, use that to set up the compressed class space list.
559 void Metaspace::initialize_class_space(ReservedSpace rs) {
560 assert(rs.size() >= CompressedClassSpaceSize,
561 SIZE_FORMAT " != " SIZE_FORMAT, rs.size(), CompressedClassSpaceSize);
562 assert(using_class_space(), "Must be using class space");
563
564 assert(rs.size() == CompressedClassSpaceSize, SIZE_FORMAT " != " SIZE_FORMAT,
565 rs.size(), CompressedClassSpaceSize);
566 assert(is_aligned(rs.base(), Metaspace::reserve_alignment()) &&
567 is_aligned(rs.size(), Metaspace::reserve_alignment()),
568 "wrong alignment");
569
570 MetaspaceContext::initialize_class_space_context(rs);
571
572 // This does currently not work because rs may be the result of a split
573 // operation and NMT seems not to be able to handle splits.
574 // Will be fixed with JDK-8243535.
575 // MemTracker::record_virtual_memory_type((address)rs.base(), mtClass);
576
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 at an address suitable for en/decoding narrow
585 // Klass pointers (see: CompressedClassPointers::is_valid_base()).
586 // The returned address shall both be suitable as a compressed class pointers
587 // base, and aligned to Metaspace::reserve_alignment (which is equal to or a
588 // multiple of allocation granularity).
589 // On error, returns an unreserved space.
590 ReservedSpace Metaspace::reserve_address_space_for_compressed_classes(size_t size) {
591
592 // Note: code below is broken and needs rethinking since it confuses encoding base
593 // with compressed class space attach address; both don't have be the same.
594 // That is also the reason why we atm don't get zero-based encoding for aarch.
595 // Comment is also wrong, at least for 9-bit shift.
596
597 // Will be fixed. For now it works well enough.
598
599 #if defined(AARCH64) || defined(PPC64)
600 const size_t alignment = Metaspace::reserve_alignment();
601
602 // AArch64: Try to align metaspace so that we can decode a compressed
603 // klass with a single MOVK instruction. We can do this iff the
604 // compressed class base is a multiple of 4G.
605 // Additionally, above 32G, ensure the lower LogKlassAlignmentInBytes bits
606 // of the upper 32-bits of the address are zero so we can handle a shift
607 // when decoding.
608
609 // PPC64: smaller heaps up to 2g will be mapped just below 4g. Then the
610 // attempt to place the compressed class space just after the heap fails on
611 // Linux 4.1.42 and higher because the launcher is loaded at 4g
612 // (ELF_ET_DYN_BASE). In that case we reach here and search the address space
613 // below 32g to get a zerobased CCS. For simplicity we reuse the search
614 // strategy for AARCH64.
615
616 static const struct {
617 address from;
618 address to;
619 size_t increment;
620 } search_ranges[] = {
621 { (address)(4*G), (address)(32*G), 4*G, },
622 { (address)(32*G), (address)(1024*G), (4 << LogKlassAlignmentInBytes) * G },
623 { nullptr, nullptr, 0 }
624 };
625
626 for (int i = 0; search_ranges[i].from != nullptr; i ++) {
627 address a = search_ranges[i].from;
628 if (CompressedKlassPointers::is_valid_base(a)) {
629 while (a < search_ranges[i].to) {
630 ReservedSpace rs(size, Metaspace::reserve_alignment(),
631 os::vm_page_size(), (char*)a);
632 if (rs.is_reserved()) {
633 assert(a == (address)rs.base(), "Sanity");
634 return rs;
635 }
636 a += search_ranges[i].increment;
637 }
638 }
639 }
640 #endif // defined(AARCH64) || defined(PPC64)
641
642 #ifdef AARCH64
643 // Note: on AARCH64, if the code above does not find any good placement, we
644 // have no recourse. We return an empty space and the VM will exit.
645 return ReservedSpace();
646 #else
647 // Default implementation: Just reserve anywhere.
648 return ReservedSpace(size, Metaspace::reserve_alignment(), os::vm_page_size(), (char*)nullptr);
649 #endif // AARCH64
650 }
651
652 #endif // _LP64
653
654 size_t Metaspace::reserve_alignment_words() {
655 return metaspace::Settings::virtual_space_node_reserve_alignment_words();
656 }
657
658 size_t Metaspace::commit_alignment_words() {
659 return metaspace::Settings::commit_granule_words();
660 }
661
662 void Metaspace::ergo_initialize() {
663
664 // Must happen before using any setting from Settings::---
665 metaspace::Settings::ergo_initialize();
666
667 // MaxMetaspaceSize and CompressedClassSpaceSize:
668 //
669 // MaxMetaspaceSize is the maximum size, in bytes, of memory we are allowed
670 // to commit for the Metaspace.
671 // It is just a number; a limit we compare against before committing. It
672 // does not have to be aligned to anything.
673 // It gets used as compare value before attempting to increase the metaspace
674 // commit charge. It defaults to max_uintx (unlimited).
675 //
676 // CompressedClassSpaceSize is the size, in bytes, of the address range we
677 // pre-reserve for the compressed class space (if we use class space).
678 // This size has to be aligned to the metaspace reserve alignment (to the
679 // size of a root chunk). It gets aligned up from whatever value the caller
680 // gave us to the next multiple of root chunk size.
681 //
682 // Note: Strictly speaking MaxMetaspaceSize and CompressedClassSpaceSize have
683 // very little to do with each other. The notion often encountered:
684 // MaxMetaspaceSize = CompressedClassSpaceSize + <non-class metadata size>
685 // is subtly wrong: MaxMetaspaceSize can besmaller than CompressedClassSpaceSize,
686 // in which case we just would not be able to fully commit the class space range.
687 //
688 // We still adjust CompressedClassSpaceSize to reasonable limits, mainly to
689 // save on reserved space, and to make ergnonomics less confusing.
690
691 MaxMetaspaceSize = MAX2(MaxMetaspaceSize, commit_alignment());
692
693 if (UseCompressedClassPointers) {
694 // Let CCS size not be larger than 80% of MaxMetaspaceSize. Note that is
695 // grossly over-dimensioned for most usage scenarios; typical ratio of
696 // class space : non class space usage is about 1:6. With many small classes,
697 // it can get as low as 1:2. It is not a big deal though since ccs is only
698 // reserved and will be committed on demand only.
699 size_t max_ccs_size = MaxMetaspaceSize * 0.8;
700 size_t adjusted_ccs_size = MIN2(CompressedClassSpaceSize, max_ccs_size);
701
702 // CCS must be aligned to root chunk size, and be at least the size of one
703 // root chunk.
704 adjusted_ccs_size = align_up(adjusted_ccs_size, reserve_alignment());
705 adjusted_ccs_size = MAX2(adjusted_ccs_size, reserve_alignment());
706
707 // Note: re-adjusting may have us left with a CompressedClassSpaceSize
708 // larger than MaxMetaspaceSize for very small values of MaxMetaspaceSize.
709 // Lets just live with that, its not a big deal.
710
711 if (adjusted_ccs_size != CompressedClassSpaceSize) {
712 FLAG_SET_ERGO(CompressedClassSpaceSize, adjusted_ccs_size);
713 log_info(metaspace)("Setting CompressedClassSpaceSize to " SIZE_FORMAT ".",
714 CompressedClassSpaceSize);
715 }
716 }
717
718 // Set MetaspaceSize, MinMetaspaceExpansion and MaxMetaspaceExpansion
719 if (MetaspaceSize > MaxMetaspaceSize) {
720 MetaspaceSize = MaxMetaspaceSize;
721 }
722
723 MetaspaceSize = align_down_bounded(MetaspaceSize, commit_alignment());
724
725 assert(MetaspaceSize <= MaxMetaspaceSize, "MetaspaceSize should be limited by MaxMetaspaceSize");
726
727 MinMetaspaceExpansion = align_down_bounded(MinMetaspaceExpansion, commit_alignment());
728 MaxMetaspaceExpansion = align_down_bounded(MaxMetaspaceExpansion, commit_alignment());
729
730 }
731
732 void Metaspace::global_initialize() {
733 MetaspaceGC::initialize(); // <- since we do not prealloc init chunks anymore is this still needed?
734
735 metaspace::ChunkHeaderPool::initialize();
736
737 if (DumpSharedSpaces) {
738 assert(!UseSharedSpaces, "sanity");
739 MetaspaceShared::initialize_for_static_dump();
740 }
741
742 // If UseCompressedClassPointers=1, we have two cases:
743 // a) if CDS is active (runtime, Xshare=on), it will create the class space
744 // for us, initialize it and set up CompressedKlassPointers encoding.
745 // Class space will be reserved above the mapped archives.
746 // b) if CDS either deactivated (Xshare=off) or a static dump is to be done (Xshare:dump),
747 // we will create the class space on our own. It will be placed above the java heap,
748 // since we assume it has been placed in low
749 // address regions. We may rethink this (see JDK-8244943). Failing that,
750 // it will be placed anywhere.
751
752 #if INCLUDE_CDS
753 // case (a)
754 if (UseSharedSpaces) {
755 if (!FLAG_IS_DEFAULT(CompressedClassSpaceBaseAddress)) {
756 log_warning(metaspace)("CDS active - ignoring CompressedClassSpaceBaseAddress.");
757 }
758 MetaspaceShared::initialize_runtime_shared_and_meta_spaces();
759 // If any of the archived space fails to map, UseSharedSpaces
760 // is reset to false.
761 }
762 #endif // INCLUDE_CDS
763
764 #ifdef _LP64
765
766 if (using_class_space() && !class_space_is_initialized()) {
767 assert(!UseSharedSpaces, "CDS archive is not mapped at this point");
768
769 // case (b) (No CDS)
770 ReservedSpace rs;
771 const size_t size = align_up(CompressedClassSpaceSize, Metaspace::reserve_alignment());
772 address base = nullptr;
773
774 // If CompressedClassSpaceBaseAddress is set, we attempt to force-map class space to
775 // the given address. This is a debug-only feature aiding tests. Due to the ASLR lottery
776 // this may fail, in which case the VM will exit after printing an appropriate message.
777 // Tests using this switch should cope with that.
778 if (CompressedClassSpaceBaseAddress != 0) {
779 base = (address)CompressedClassSpaceBaseAddress;
780 if (!is_aligned(base, Metaspace::reserve_alignment())) {
781 vm_exit_during_initialization(
782 err_msg("CompressedClassSpaceBaseAddress=" PTR_FORMAT " invalid "
783 "(must be aligned to " SIZE_FORMAT_X ").",
784 CompressedClassSpaceBaseAddress, Metaspace::reserve_alignment()));
785 }
786 rs = ReservedSpace(size, Metaspace::reserve_alignment(),
787 os::vm_page_size() /* large */, (char*)base);
788 if (rs.is_reserved()) {
789 log_info(metaspace)("Successfully forced class space address to " PTR_FORMAT, p2i(base));
790 } else {
791 vm_exit_during_initialization(
792 err_msg("CompressedClassSpaceBaseAddress=" PTR_FORMAT " given, but reserving class space failed.",
793 CompressedClassSpaceBaseAddress));
794 }
795 }
796
797 if (!rs.is_reserved()) {
798 // If UseCompressedOops=1 and the java heap has been placed in coops-friendly
799 // territory, i.e. its base is under 32G, then we attempt to place ccs
800 // right above the java heap.
801 // Otherwise the lower 32G are still free. We try to place ccs at the lowest
802 // allowed mapping address.
803 base = (UseCompressedOops && (uint64_t)CompressedOops::base() < OopEncodingHeapMax) ?
804 CompressedOops::end() : (address)HeapBaseMinAddress;
805 base = align_up(base, Metaspace::reserve_alignment());
806
807 if (base != nullptr) {
808 if (CompressedKlassPointers::is_valid_base(base)) {
809 rs = ReservedSpace(size, Metaspace::reserve_alignment(),
810 os::vm_page_size(), (char*)base);
811 }
812 }
813 }
814
815 // ...failing that, reserve anywhere, but let platform do optimized placement:
816 if (!rs.is_reserved()) {
817 rs = Metaspace::reserve_address_space_for_compressed_classes(size);
818 }
819
820 // ...failing that, give up.
821 if (!rs.is_reserved()) {
822 vm_exit_during_initialization(
823 err_msg("Could not allocate compressed class space: " SIZE_FORMAT " bytes",
824 CompressedClassSpaceSize));
825 }
826
827 // Initialize space
828 Metaspace::initialize_class_space(rs);
829
830 // Set up compressed class pointer encoding.
831 CompressedKlassPointers::initialize((address)rs.base(), rs.size());
832 }
833
834 #endif
835
836 // Initialize non-class virtual space list, and its chunk manager:
837 MetaspaceContext::initialize_nonclass_space_context();
838
839 _tracer = new MetaspaceTracer();
840
841 // We must prevent the very first address of the ccs from being used to store
842 // metadata, since that address would translate to a narrow pointer of 0, and the
843 // VM does not distinguish between "narrow 0 as in null" and "narrow 0 as in start
844 // of ccs".
845 // Before Elastic Metaspace that did not happen due to the fact that every Metachunk
846 // had a header and therefore could not allocate anything at offset 0.
847 #ifdef _LP64
848 if (using_class_space()) {
849 // The simplest way to fix this is to allocate a tiny dummy chunk right at the
850 // start of ccs and do not use it for anything.
851 MetaspaceContext::context_class()->cm()->get_chunk(metaspace::chunklevel::HIGHEST_CHUNK_LEVEL);
852 }
853 #endif
854
855 #ifdef _LP64
856 if (UseCompressedClassPointers) {
857 // Note: "cds" would be a better fit but keep this for backward compatibility.
858 LogTarget(Info, gc, metaspace) lt;
859 if (lt.is_enabled()) {
860 ResourceMark rm;
861 LogStream ls(lt);
862 CDS_ONLY(MetaspaceShared::print_on(&ls);)
863 Metaspace::print_compressed_class_space(&ls);
864 CompressedKlassPointers::print_mode(&ls);
865 }
866 }
867 #endif
868
869 }
870
871 void Metaspace::post_initialize() {
872 MetaspaceGC::post_initialize();
873 }
874
875 size_t Metaspace::max_allocation_word_size() {
876 return metaspace::chunklevel::MAX_CHUNK_WORD_SIZE;
877 }
878
879 #ifdef _LP64
880 // The largest allowed size for class space
881 size_t Metaspace::max_class_space_size() {
882 assert(KlassEncodingMetaspaceMax > 0, "too early.");
883 // This is a bit fuzzy. Max value of class space size depends on narrow klass pointer
884 // encoding range size and CDS, since class space shares encoding range with CDS. CDS
885 // archives are usually pretty small though, so to keep matters simple, for now we
886 // just assume a reasonable default (this is hackish; improve!).
887 const size_t slice_for_cds = M * 128;
888 assert(KlassEncodingMetaspaceMax >= (slice_for_cds * 2), "rethink this");
889 const size_t max_class_space_size = KlassEncodingMetaspaceMax - slice_for_cds;
890 return max_class_space_size;
891 }
892 #endif // _LP64
893
894 // This version of Metaspace::allocate does not throw OOM but simply returns null, and
895 // is suitable for calling from non-Java threads.
896 // Callers are responsible for checking null.
897 MetaWord* Metaspace::allocate(ClassLoaderData* loader_data, size_t word_size,
898 MetaspaceObj::Type type) {
899 assert(word_size <= Metaspace::max_allocation_word_size(),
900 "allocation size too large (" SIZE_FORMAT ")", word_size);
901
902 assert(loader_data != nullptr, "Should never pass around a nullptr loader_data. "
903 "ClassLoaderData::the_null_class_loader_data() should have been used.");
904
905 // Deal with concurrent unloading failed allocation starvation
906 MetaspaceCriticalAllocation::block_if_concurrent_purge();
907
908 MetadataType mdtype = (type == MetaspaceObj::ClassType) ? ClassType : NonClassType;
909
910 // Try to allocate metadata.
911 MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
912
913 if (result != nullptr) {
914 // Zero initialize.
915 Copy::fill_to_words((HeapWord*)result, word_size, 0);
916
917 log_trace(metaspace)("Metaspace::allocate: type %d return " PTR_FORMAT ".", (int)type, p2i(result));
918 }
919
920 return result;
921 }
922
923 MetaWord* Metaspace::allocate(ClassLoaderData* loader_data, size_t word_size,
924 MetaspaceObj::Type type, TRAPS) {
925
926 if (HAS_PENDING_EXCEPTION) {
927 assert(false, "Should not allocate with exception pending");
928 return nullptr; // caller does a CHECK_NULL too
929 }
930
931 MetaWord* result = allocate(loader_data, word_size, type);
932
933 if (result == nullptr) {
934 MetadataType mdtype = (type == MetaspaceObj::ClassType) ? ClassType : NonClassType;
935 tracer()->report_metaspace_allocation_failure(loader_data, word_size, type, mdtype);
936
937 // Allocation failed.
938 if (is_init_completed()) {
939 // Only start a GC if the bootstrapping has completed.
940 // Try to clean out some heap memory and retry. This can prevent premature
941 // expansion of the metaspace.
942 result = Universe::heap()->satisfy_failed_metadata_allocation(loader_data, word_size, mdtype);
943 }
944
945 if (result == nullptr) {
946 report_metadata_oome(loader_data, word_size, type, mdtype, THREAD);
947 assert(HAS_PENDING_EXCEPTION, "sanity");
948 return nullptr;
949 }
950
951 // Zero initialize.
952 Copy::fill_to_words((HeapWord*)result, word_size, 0);
953
954 log_trace(metaspace)("Metaspace::allocate: type %d return " PTR_FORMAT ".", (int)type, p2i(result));
955 }
956
957 return result;
958 }
959
960 void Metaspace::report_metadata_oome(ClassLoaderData* loader_data, size_t word_size, MetaspaceObj::Type type, MetadataType mdtype, TRAPS) {
961 tracer()->report_metadata_oom(loader_data, word_size, type, mdtype);
962
963 // If result is still null, we are out of memory.
964 Log(gc, metaspace, freelist, oom) log;
965 if (log.is_info()) {
966 log.info("Metaspace (%s) allocation failed for size " SIZE_FORMAT,
967 is_class_space_allocation(mdtype) ? "class" : "data", word_size);
968 ResourceMark rm;
969 if (log.is_debug()) {
970 if (loader_data->metaspace_or_null() != nullptr) {
971 LogStream ls(log.debug());
972 loader_data->print_value_on(&ls);
973 }
974 }
975 LogStream ls(log.info());
976 // In case of an OOM, log out a short but still useful report.
977 MetaspaceUtils::print_basic_report(&ls, 0);
978 }
979
980 bool out_of_compressed_class_space = false;
981 if (is_class_space_allocation(mdtype)) {
982 ClassLoaderMetaspace* metaspace = loader_data->metaspace_non_null();
983 out_of_compressed_class_space =
984 MetaspaceUtils::committed_bytes(Metaspace::ClassType) +
985 align_up(word_size * BytesPerWord, 4 * M) >
986 CompressedClassSpaceSize;
987 }
988
989 // -XX:+HeapDumpOnOutOfMemoryError and -XX:OnOutOfMemoryError support
990 const char* space_string = out_of_compressed_class_space ?
991 "Compressed class space" : "Metaspace";
992
993 report_java_out_of_memory(space_string);
994
995 if (JvmtiExport::should_post_resource_exhausted()) {
996 JvmtiExport::post_resource_exhausted(
997 JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR,
998 space_string);
999 }
1000
1001 if (!is_init_completed()) {
1002 vm_exit_during_initialization("OutOfMemoryError", space_string);
1003 }
1004
1005 if (out_of_compressed_class_space) {
1006 THROW_OOP(Universe::out_of_memory_error_class_metaspace());
1007 } else {
1008 THROW_OOP(Universe::out_of_memory_error_metaspace());
1009 }
1010 }
1011
1012 const char* Metaspace::metadata_type_name(Metaspace::MetadataType mdtype) {
1013 switch (mdtype) {
1014 case Metaspace::ClassType: return "Class";
1015 case Metaspace::NonClassType: return "Metadata";
1016 default:
1017 assert(false, "Got bad mdtype: %d", (int) mdtype);
1018 return nullptr;
1019 }
1020 }
1021
1022 void Metaspace::purge(bool classes_unloaded) {
1023 // The MetaspaceCritical_lock is used by a concurrent GC to block out concurrent metaspace
1024 // allocations, that would starve critical metaspace allocations, that are about to throw
1025 // OOM if they fail; they need precedence for correctness.
1026 MutexLocker ml(MetaspaceCritical_lock, Mutex::_no_safepoint_check_flag);
1027 if (classes_unloaded) {
1028 ChunkManager* cm = ChunkManager::chunkmanager_nonclass();
1029 if (cm != nullptr) {
1030 cm->purge();
1031 }
1032 if (using_class_space()) {
1033 cm = ChunkManager::chunkmanager_class();
1034 if (cm != nullptr) {
1035 cm->purge();
1036 }
1037 }
1038 }
1039
1040 // Try to satisfy queued metaspace allocation requests.
1041 //
1042 // It might seem unnecessary to try to process allocation requests if no
1043 // classes have been unloaded. However, this call is required for the code
1044 // in MetaspaceCriticalAllocation::try_allocate_critical to work.
1045 MetaspaceCriticalAllocation::process();
1046 }
1047
1048 bool Metaspace::contains(const void* ptr) {
1049 if (MetaspaceShared::is_in_shared_metaspace(ptr)) {
1050 return true;
1051 }
1052 return contains_non_shared(ptr);
1053 }
1054
1055 bool Metaspace::contains_non_shared(const void* ptr) {
1056 if (using_class_space() && VirtualSpaceList::vslist_class()->contains((MetaWord*)ptr)) {
1057 return true;
1058 }
1059
1060 return VirtualSpaceList::vslist_nonclass()->contains((MetaWord*)ptr);
1061 }