1 /*
2 * Copyright (c) 2011, 2020, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #include "precompiled.hpp"
26
27 #include "aot/aotLoader.hpp"
28 #include "gc/shared/collectedHeap.hpp"
29 #include "logging/log.hpp"
30 #include "logging/logStream.hpp"
31 #include "memory/filemap.hpp"
32 #include "memory/metaspace/metaspaceSizesSnapshot.hpp"
33 #include "memory/metaspace/msChunkHeaderPool.hpp"
34 #include "memory/metaspace/msChunkManager.hpp"
35 #include "memory/metaspace/msCommitLimiter.hpp"
36 #include "memory/metaspace/msCommon.hpp"
37 #include "memory/metaspace/msContext.hpp"
38 #include "memory/metaspace/msReport.hpp"
39 #include "memory/metaspace/msRunningCounters.hpp"
40 #include "memory/metaspace/msSettings.hpp"
41 #include "memory/metaspace/msVirtualSpaceList.hpp"
42 #include "memory/metaspace.hpp"
43 #include "memory/metaspaceShared.hpp"
44 #include "memory/metaspaceTracer.hpp"
45 #include "memory/universe.hpp"
46 #include "oops/compressedOops.hpp"
47 #include "runtime/atomic.hpp"
48 #include "runtime/init.hpp"
49 #include "runtime/java.hpp"
50 #include "services/memTracker.hpp"
51 #include "utilities/copy.hpp"
52 #include "utilities/debug.hpp"
53 #include "utilities/formatBuffer.hpp"
54 #include "utilities/globalDefinitions.hpp"
55
56
57 using metaspace::ChunkManager;
58 using metaspace::CommitLimiter;
59 using metaspace::MetaspaceContext;
60 using metaspace::MetaspaceReporter;
61 using metaspace::RunningCounters;
62 using metaspace::VirtualSpaceList;
63
64
65 size_t MetaspaceUtils::used_words() {
66 return RunningCounters::used_words();
67 }
68
69 size_t MetaspaceUtils::used_words(Metaspace::MetadataType mdtype) {
70 return Metaspace::is_class_space_allocation(mdtype) ? RunningCounters::used_words_class() : RunningCounters::used_words_nonclass();
71 }
72
73 size_t MetaspaceUtils::reserved_words() {
74 return RunningCounters::reserved_words();
75 }
76
77 size_t MetaspaceUtils::reserved_words(Metaspace::MetadataType mdtype) {
78 return Metaspace::is_class_space_allocation(mdtype) ? RunningCounters::reserved_words_class() : RunningCounters::reserved_words_nonclass();
79 }
80
81 size_t MetaspaceUtils::committed_words() {
82 return RunningCounters::committed_words();
83 }
84
85 size_t MetaspaceUtils::committed_words(Metaspace::MetadataType mdtype) {
86 return Metaspace::is_class_space_allocation(mdtype) ? RunningCounters::committed_words_class() : RunningCounters::committed_words_nonclass();
87 }
88
89
90
91 void MetaspaceUtils::print_metaspace_change(const metaspace::MetaspaceSizesSnapshot& pre_meta_values) {
92 const metaspace::MetaspaceSizesSnapshot meta_values;
93
94 // We print used and committed since these are the most useful at-a-glance vitals for Metaspace:
95 // - used tells you how much memory is actually used for metadata
96 // - committed tells you how much memory is committed for the purpose of metadata
97 // The difference between those two would be waste, which can have various forms (freelists,
98 // unused parts of committed chunks etc)
99 //
100 // Left out is reserved, since this is not as exciting as the first two values: for class space,
101 // it is a constant (to uninformed users, often confusingly large). For non-class space, it would
102 // be interesting since free chunks can be uncommitted, but for now it is left out.
103
104 if (Metaspace::using_class_space()) {
105 log_info(gc, metaspace)(HEAP_CHANGE_FORMAT" "
106 HEAP_CHANGE_FORMAT" "
107 HEAP_CHANGE_FORMAT,
108 HEAP_CHANGE_FORMAT_ARGS("Metaspace",
109 pre_meta_values.used(),
110 pre_meta_values.committed(),
111 meta_values.used(),
112 meta_values.committed()),
113 HEAP_CHANGE_FORMAT_ARGS("NonClass",
114 pre_meta_values.non_class_used(),
115 pre_meta_values.non_class_committed(),
116 meta_values.non_class_used(),
117 meta_values.non_class_committed()),
118 HEAP_CHANGE_FORMAT_ARGS("Class",
119 pre_meta_values.class_used(),
120 pre_meta_values.class_committed(),
121 meta_values.class_used(),
122 meta_values.class_committed()));
123 } else {
124 log_info(gc, metaspace)(HEAP_CHANGE_FORMAT,
125 HEAP_CHANGE_FORMAT_ARGS("Metaspace",
126 pre_meta_values.used(),
127 pre_meta_values.committed(),
128 meta_values.used(),
129 meta_values.committed()));
130 }
131 }
132
133 // This will print out a basic metaspace usage report but
134 // unlike print_report() is guaranteed not to lock or to walk the CLDG.
135 void MetaspaceUtils::print_basic_report(outputStream* out, size_t scale) {
136 MetaspaceReporter::print_basic_report(out, scale);
137 }
138
139 // Prints a report about the current metaspace state.
140 // Optional parts can be enabled via flags.
141 // Function will walk the CLDG and will lock the expand lock; if that is not
142 // convenient, use print_basic_report() instead.
143 void MetaspaceUtils::print_report(outputStream* out, size_t scale) {
144 const int flags =
145 (int)MetaspaceReporter::Option::ShowLoaders |
146 (int)MetaspaceReporter::Option::BreakDownByChunkType |
147 (int)MetaspaceReporter::Option::ShowClasses;
148 MetaspaceReporter::print_report(out, scale, flags);
149 }
150
151 void MetaspaceUtils::print_on(outputStream* out) {
152
153 // Used from all GCs. It first prints out totals, then, separately, the class space portion.
154
155 out->print_cr(" Metaspace "
156 "used " SIZE_FORMAT "K, "
157 "committed " SIZE_FORMAT "K, "
158 "reserved " SIZE_FORMAT "K",
159 used_bytes()/K,
160 committed_bytes()/K,
161 reserved_bytes()/K);
162
163 if (Metaspace::using_class_space()) {
164 const Metaspace::MetadataType ct = Metaspace::ClassType;
165 out->print_cr(" class space "
166 "used " SIZE_FORMAT "K, "
167 "committed " SIZE_FORMAT "K, "
168 "reserved " SIZE_FORMAT "K",
169 used_bytes(ct)/K,
170 committed_bytes(ct)/K,
171 reserved_bytes(ct)/K);
172 }
173 }
174
175 #ifdef ASSERT
176 void MetaspaceUtils::verify() {
177 if (Metaspace::initialized()) {
178
179 // Verify non-class chunkmanager...
180 ChunkManager* cm = ChunkManager::chunkmanager_nonclass();
181 cm->verify();
182
183 // ... and space list.
184 VirtualSpaceList* vsl = VirtualSpaceList::vslist_nonclass();
185 vsl->verify();
186
187 if (Metaspace::using_class_space()) {
188 // If we use compressed class pointers, verify class chunkmanager...
189 cm = ChunkManager::chunkmanager_class();
190 cm->verify();
191
192 // ... and class spacelist.
193 vsl = VirtualSpaceList::vslist_class();
194 vsl->verify();
195 }
196
197 }
198 }
199 #endif
200
201 ////////////////////////////////7
202 // MetaspaceGC methods
203
204 volatile size_t MetaspaceGC::_capacity_until_GC = 0;
205 uint MetaspaceGC::_shrink_factor = 0;
206
207 // VM_CollectForMetadataAllocation is the vm operation used to GC.
208 // Within the VM operation after the GC the attempt to allocate the metadata
209 // should succeed. If the GC did not free enough space for the metaspace
210 // allocation, the HWM is increased so that another virtualspace will be
211 // allocated for the metadata. With perm gen the increase in the perm
212 // gen had bounds, MinMetaspaceExpansion and MaxMetaspaceExpansion. The
213 // metaspace policy uses those as the small and large steps for the HWM.
214 //
215 // After the GC the compute_new_size() for MetaspaceGC is called to
216 // resize the capacity of the metaspaces. The current implementation
217 // is based on the flags MinMetaspaceFreeRatio and MaxMetaspaceFreeRatio used
218 // to resize the Java heap by some GC's. New flags can be implemented
219 // if really needed. MinMetaspaceFreeRatio is used to calculate how much
220 // free space is desirable in the metaspace capacity to decide how much
221 // to increase the HWM. MaxMetaspaceFreeRatio is used to decide how much
222 // free space is desirable in the metaspace capacity before decreasing
223 // the HWM.
224
225 // Calculate the amount to increase the high water mark (HWM).
226 // Increase by a minimum amount (MinMetaspaceExpansion) so that
227 // another expansion is not requested too soon. If that is not
228 // enough to satisfy the allocation, increase by MaxMetaspaceExpansion.
229 // If that is still not enough, expand by the size of the allocation
230 // plus some.
231 size_t MetaspaceGC::delta_capacity_until_GC(size_t bytes) {
232 size_t min_delta = MinMetaspaceExpansion;
233 size_t max_delta = MaxMetaspaceExpansion;
234 size_t delta = align_up(bytes, Metaspace::commit_alignment());
235
236 if (delta <= min_delta) {
237 delta = min_delta;
238 } else if (delta <= max_delta) {
239 // Don't want to hit the high water mark on the next
240 // allocation so make the delta greater than just enough
241 // for this allocation.
242 delta = max_delta;
243 } else {
244 // This allocation is large but the next ones are probably not
245 // so increase by the minimum.
246 delta = delta + min_delta;
247 }
248
249 assert_is_aligned(delta, Metaspace::commit_alignment());
250
251 return delta;
252 }
253
254 size_t MetaspaceGC::capacity_until_GC() {
255 size_t value = Atomic::load_acquire(&_capacity_until_GC);
256 assert(value >= MetaspaceSize, "Not initialized properly?");
257 return value;
258 }
259
260 // Try to increase the _capacity_until_GC limit counter by v bytes.
261 // Returns true if it succeeded. It may fail if either another thread
262 // concurrently increased the limit or the new limit would be larger
263 // than MaxMetaspaceSize.
264 // On success, optionally returns new and old metaspace capacity in
265 // new_cap_until_GC and old_cap_until_GC respectively.
266 // On error, optionally sets can_retry to indicate whether if there is
267 // actually enough space remaining to satisfy the request.
268 bool MetaspaceGC::inc_capacity_until_GC(size_t v, size_t* new_cap_until_GC, size_t* old_cap_until_GC, bool* can_retry) {
269 assert_is_aligned(v, Metaspace::commit_alignment());
270
271 size_t old_capacity_until_GC = _capacity_until_GC;
272 size_t new_value = old_capacity_until_GC + v;
273
274 if (new_value < old_capacity_until_GC) {
275 // The addition wrapped around, set new_value to aligned max value.
276 new_value = align_down(max_uintx, Metaspace::commit_alignment());
277 }
278
279 if (new_value > MaxMetaspaceSize) {
280 if (can_retry != NULL) {
281 *can_retry = false;
282 }
283 return false;
284 }
285
286 if (can_retry != NULL) {
287 *can_retry = true;
288 }
289 size_t prev_value = Atomic::cmpxchg(&_capacity_until_GC, old_capacity_until_GC, new_value);
290
291 if (old_capacity_until_GC != prev_value) {
292 return false;
293 }
294
295 if (new_cap_until_GC != NULL) {
296 *new_cap_until_GC = new_value;
297 }
298 if (old_cap_until_GC != NULL) {
299 *old_cap_until_GC = old_capacity_until_GC;
300 }
301 return true;
302 }
303
304 size_t MetaspaceGC::dec_capacity_until_GC(size_t v) {
305 assert_is_aligned(v, Metaspace::commit_alignment());
306
307 return Atomic::sub(&_capacity_until_GC, v);
308 }
309
310 void MetaspaceGC::initialize() {
311 // Set the high-water mark to MaxMetapaceSize during VM initializaton since
312 // we can't do a GC during initialization.
313 _capacity_until_GC = MaxMetaspaceSize;
314 }
315
316 void MetaspaceGC::post_initialize() {
317 // Reset the high-water mark once the VM initialization is done.
318 _capacity_until_GC = MAX2(MetaspaceUtils::committed_bytes(), MetaspaceSize);
319 }
320
321 bool MetaspaceGC::can_expand(size_t word_size, bool is_class) {
322 // Check if the compressed class space is full.
323 if (is_class && Metaspace::using_class_space()) {
324 size_t class_committed = MetaspaceUtils::committed_bytes(Metaspace::ClassType);
325 if (class_committed + word_size * BytesPerWord > CompressedClassSpaceSize) {
326 log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by " SIZE_FORMAT " words (CompressedClassSpaceSize = " SIZE_FORMAT " words)",
327 (is_class ? "class" : "non-class"), word_size, CompressedClassSpaceSize / sizeof(MetaWord));
328 return false;
329 }
330 }
331
332 // Check if the user has imposed a limit on the metaspace memory.
333 size_t committed_bytes = MetaspaceUtils::committed_bytes();
334 if (committed_bytes + word_size * BytesPerWord > MaxMetaspaceSize) {
335 log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by " SIZE_FORMAT " words (MaxMetaspaceSize = " SIZE_FORMAT " words)",
336 (is_class ? "class" : "non-class"), word_size, MaxMetaspaceSize / sizeof(MetaWord));
337 return false;
338 }
339
340 return true;
341 }
342
343 size_t MetaspaceGC::allowed_expansion() {
344 size_t committed_bytes = MetaspaceUtils::committed_bytes();
345 size_t capacity_until_gc = capacity_until_GC();
346
347 assert(capacity_until_gc >= committed_bytes,
348 "capacity_until_gc: " SIZE_FORMAT " < committed_bytes: " SIZE_FORMAT,
349 capacity_until_gc, committed_bytes);
350
351 size_t left_until_max = MaxMetaspaceSize - committed_bytes;
352 size_t left_until_GC = capacity_until_gc - committed_bytes;
353 size_t left_to_commit = MIN2(left_until_GC, left_until_max);
354 log_trace(gc, metaspace, freelist)("allowed expansion words: " SIZE_FORMAT
355 " (left_until_max: " SIZE_FORMAT ", left_until_GC: " SIZE_FORMAT ".",
356 left_to_commit / BytesPerWord, left_until_max / BytesPerWord, left_until_GC / BytesPerWord);
357
358 return left_to_commit / BytesPerWord;
359 }
360
361 void MetaspaceGC::compute_new_size() {
362 assert(_shrink_factor <= 100, "invalid shrink factor");
363 uint current_shrink_factor = _shrink_factor;
364 _shrink_factor = 0;
365
366 // Using committed_bytes() for used_after_gc is an overestimation, since the
367 // chunk free lists are included in committed_bytes() and the memory in an
368 // un-fragmented chunk free list is available for future allocations.
369 // However, if the chunk free lists becomes fragmented, then the memory may
370 // not be available for future allocations and the memory is therefore "in use".
371 // Including the chunk free lists in the definition of "in use" is therefore
372 // necessary. Not including the chunk free lists can cause capacity_until_GC to
373 // shrink below committed_bytes() and this has caused serious bugs in the past.
374 const size_t used_after_gc = MetaspaceUtils::committed_bytes();
375 const size_t capacity_until_GC = MetaspaceGC::capacity_until_GC();
376
377 const double minimum_free_percentage = MinMetaspaceFreeRatio / 100.0;
378 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
379
380 const double min_tmp = used_after_gc / maximum_used_percentage;
381 size_t minimum_desired_capacity =
382 (size_t)MIN2(min_tmp, double(MaxMetaspaceSize));
383 // Don't shrink less than the initial generation size
384 minimum_desired_capacity = MAX2(minimum_desired_capacity,
385 MetaspaceSize);
386
387 log_trace(gc, metaspace)("MetaspaceGC::compute_new_size: ");
388 log_trace(gc, metaspace)(" minimum_free_percentage: %6.2f maximum_used_percentage: %6.2f",
389 minimum_free_percentage, maximum_used_percentage);
390 log_trace(gc, metaspace)(" used_after_gc : %6.1fKB", used_after_gc / (double) K);
391
392
393 size_t shrink_bytes = 0;
394 if (capacity_until_GC < minimum_desired_capacity) {
395 // If we have less capacity below the metaspace HWM, then
396 // increment the HWM.
397 size_t expand_bytes = minimum_desired_capacity - capacity_until_GC;
398 expand_bytes = align_up(expand_bytes, Metaspace::commit_alignment());
399 // Don't expand unless it's significant
400 if (expand_bytes >= MinMetaspaceExpansion) {
401 size_t new_capacity_until_GC = 0;
402 bool succeeded = MetaspaceGC::inc_capacity_until_GC(expand_bytes, &new_capacity_until_GC);
403 assert(succeeded, "Should always succesfully increment HWM when at safepoint");
404
405 Metaspace::tracer()->report_gc_threshold(capacity_until_GC,
406 new_capacity_until_GC,
407 MetaspaceGCThresholdUpdater::ComputeNewSize);
408 log_trace(gc, metaspace)(" expanding: minimum_desired_capacity: %6.1fKB expand_bytes: %6.1fKB MinMetaspaceExpansion: %6.1fKB new metaspace HWM: %6.1fKB",
409 minimum_desired_capacity / (double) K,
410 expand_bytes / (double) K,
411 MinMetaspaceExpansion / (double) K,
412 new_capacity_until_GC / (double) K);
413 }
414 return;
415 }
416
417 // No expansion, now see if we want to shrink
418 // We would never want to shrink more than this
419 assert(capacity_until_GC >= minimum_desired_capacity,
420 SIZE_FORMAT " >= " SIZE_FORMAT,
421 capacity_until_GC, minimum_desired_capacity);
422 size_t max_shrink_bytes = capacity_until_GC - minimum_desired_capacity;
423
424 // Should shrinking be considered?
425 if (MaxMetaspaceFreeRatio < 100) {
426 const double maximum_free_percentage = MaxMetaspaceFreeRatio / 100.0;
427 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
428 const double max_tmp = used_after_gc / minimum_used_percentage;
429 size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(MaxMetaspaceSize));
430 maximum_desired_capacity = MAX2(maximum_desired_capacity,
431 MetaspaceSize);
432 log_trace(gc, metaspace)(" maximum_free_percentage: %6.2f minimum_used_percentage: %6.2f",
433 maximum_free_percentage, minimum_used_percentage);
434 log_trace(gc, metaspace)(" minimum_desired_capacity: %6.1fKB maximum_desired_capacity: %6.1fKB",
435 minimum_desired_capacity / (double) K, maximum_desired_capacity / (double) K);
436
437 assert(minimum_desired_capacity <= maximum_desired_capacity,
438 "sanity check");
439
440 if (capacity_until_GC > maximum_desired_capacity) {
441 // Capacity too large, compute shrinking size
442 shrink_bytes = capacity_until_GC - maximum_desired_capacity;
443 // We don't want shrink all the way back to initSize if people call
444 // System.gc(), because some programs do that between "phases" and then
445 // we'd just have to grow the heap up again for the next phase. So we
446 // damp the shrinking: 0% on the first call, 10% on the second call, 40%
447 // on the third call, and 100% by the fourth call. But if we recompute
448 // size without shrinking, it goes back to 0%.
449 shrink_bytes = shrink_bytes / 100 * current_shrink_factor;
450
451 shrink_bytes = align_down(shrink_bytes, Metaspace::commit_alignment());
452
453 assert(shrink_bytes <= max_shrink_bytes,
454 "invalid shrink size " SIZE_FORMAT " not <= " SIZE_FORMAT,
455 shrink_bytes, max_shrink_bytes);
456 if (current_shrink_factor == 0) {
457 _shrink_factor = 10;
458 } else {
459 _shrink_factor = MIN2(current_shrink_factor * 4, (uint) 100);
460 }
461 log_trace(gc, metaspace)(" shrinking: initThreshold: %.1fK maximum_desired_capacity: %.1fK",
462 MetaspaceSize / (double) K, maximum_desired_capacity / (double) K);
463 log_trace(gc, metaspace)(" shrink_bytes: %.1fK current_shrink_factor: %d new shrink factor: %d MinMetaspaceExpansion: %.1fK",
464 shrink_bytes / (double) K, current_shrink_factor, _shrink_factor, MinMetaspaceExpansion / (double) K);
465 }
466 }
467
468 // Don't shrink unless it's significant
469 if (shrink_bytes >= MinMetaspaceExpansion &&
470 ((capacity_until_GC - shrink_bytes) >= MetaspaceSize)) {
471 size_t new_capacity_until_GC = MetaspaceGC::dec_capacity_until_GC(shrink_bytes);
472 Metaspace::tracer()->report_gc_threshold(capacity_until_GC,
473 new_capacity_until_GC,
474 MetaspaceGCThresholdUpdater::ComputeNewSize);
475 }
476 }
477
478
479
480 ////// Metaspace methods /////
481
482 const MetaspaceTracer* Metaspace::_tracer = NULL;
483
484 DEBUG_ONLY(bool Metaspace::_frozen = false;)
485
486 bool Metaspace::initialized() {
487 return metaspace::MetaspaceContext::context_nonclass() != NULL &&
488 (using_class_space() ? metaspace::MetaspaceContext::context_class() != NULL : true);
489 }
490
491 #ifdef _LP64
492
493 void Metaspace::print_compressed_class_space(outputStream* st) {
494 if (VirtualSpaceList::vslist_class() != NULL) {
495 MetaWord* base = VirtualSpaceList::vslist_class()->base_of_first_node();
496 size_t size = VirtualSpaceList::vslist_class()->word_size_of_first_node();
497 MetaWord* top = base + size;
498 st->print("Compressed class space mapped at: " PTR_FORMAT "-" PTR_FORMAT ", reserved size: " SIZE_FORMAT,
499 p2i(base), p2i(top), (top - base) * BytesPerWord);
500 st->cr();
501 }
502 }
503
504 // Given a prereserved space, use that to set up the compressed class space list.
505 void Metaspace::initialize_class_space(ReservedSpace rs) {
506 assert(rs.size() >= CompressedClassSpaceSize,
507 SIZE_FORMAT " != " SIZE_FORMAT, rs.size(), CompressedClassSpaceSize);
508 assert(using_class_space(), "Must be using class space");
509
510 assert(rs.size() == CompressedClassSpaceSize, SIZE_FORMAT " != " SIZE_FORMAT,
511 rs.size(), CompressedClassSpaceSize);
512 assert(is_aligned(rs.base(), Metaspace::reserve_alignment()) &&
513 is_aligned(rs.size(), Metaspace::reserve_alignment()),
514 "wrong alignment");
515
516 MetaspaceContext::initialize_class_space_context(rs);
517
518 // This does currently not work because rs may be the result of a split
519 // operation and NMT seems not to be able to handle splits.
520 // Will be fixed with JDK-8243535.
521 // MemTracker::record_virtual_memory_type((address)rs.base(), mtClass);
522
523 }
524
525 // Returns true if class space has been setup (initialize_class_space).
526 bool Metaspace::class_space_is_initialized() {
527 return MetaspaceContext::context_class() != NULL;
528 }
529
530 // Reserve a range of memory at an address suitable for en/decoding narrow
531 // Klass pointers (see: CompressedClassPointers::is_valid_base()).
532 // The returned address shall both be suitable as a compressed class pointers
533 // base, and aligned to Metaspace::reserve_alignment (which is equal to or a
534 // multiple of allocation granularity).
535 // On error, returns an unreserved space.
536 ReservedSpace Metaspace::reserve_address_space_for_compressed_classes(size_t size) {
537
538 #ifdef AARCH64
539 const size_t alignment = Metaspace::reserve_alignment();
540
541 // AArch64: Try to align metaspace so that we can decode a compressed
542 // klass with a single MOVK instruction. We can do this iff the
543 // compressed class base is a multiple of 4G.
544 // Additionally, above 32G, ensure the lower LogKlassAlignmentInBytes bits
545 // of the upper 32-bits of the address are zero so we can handle a shift
546 // when decoding.
547
548 static const struct {
549 address from;
550 address to;
551 size_t increment;
552 } search_ranges[] = {
553 { (address)(4*G), (address)(32*G), 4*G, },
554 { (address)(32*G), (address)(1024*G), (4 << LogKlassAlignmentInBytes) * G },
555 { NULL, NULL, 0 }
556 };
557
558 for (int i = 0; search_ranges[i].from != NULL; i ++) {
559 address a = search_ranges[i].from;
560 assert(CompressedKlassPointers::is_valid_base(a), "Sanity");
561 while (a < search_ranges[i].to) {
562 ReservedSpace rs(size, Metaspace::reserve_alignment(),
563 false /*large_pages*/, (char*)a);
564 if (rs.is_reserved()) {
565 assert(a == (address)rs.base(), "Sanity");
566 return rs;
567 }
568 a += search_ranges[i].increment;
569 }
570 }
571
572 // Note: on AARCH64, if the code above does not find any good placement, we
573 // have no recourse. We return an empty space and the VM will exit.
574 return ReservedSpace();
575 #else
576 // Default implementation: Just reserve anywhere.
577 return ReservedSpace(size, Metaspace::reserve_alignment(), false, (char*)NULL);
578 #endif // AARCH64
579 }
580
581 #endif // _LP64
582
583
584 size_t Metaspace::reserve_alignment_words() {
585 return metaspace::Settings::virtual_space_node_reserve_alignment_words();
586 }
587
588 size_t Metaspace::commit_alignment_words() {
589 return metaspace::Settings::commit_granule_words();
590 }
591
592 void Metaspace::ergo_initialize() {
593
594 // Must happen before using any setting from Settings::---
595 metaspace::Settings::ergo_initialize();
596
597 // MaxMetaspaceSize and CompressedClassSpaceSize:
598 //
599 // MaxMetaspaceSize is the maximum size, in bytes, of memory we are allowed
600 // to commit for the Metaspace.
601 // It is just a number; a limit we compare against before committing. It
602 // does not have to be aligned to anything.
603 // It gets used as compare value in class CommitLimiter.
604 // It is set to max_uintx in globals.hpp by default, so by default it does
605 // not limit anything.
606 //
607 // CompressedClassSpaceSize is the size, in bytes, of the address range we
608 // pre-reserve for the compressed class space (if we use class space).
609 // This size has to be aligned to the metaspace reserve alignment (to the
610 // size of a root chunk). It gets aligned up from whatever value the caller
611 // gave us to the next multiple of root chunk size.
612 //
613 // Note: Strictly speaking MaxMetaspaceSize and CompressedClassSpaceSize have
614 // very little to do with each other. The notion often encountered:
615 // MaxMetaspaceSize = CompressedClassSpaceSize + <non-class metadata size>
616 // is subtly wrong: MaxMetaspaceSize can besmaller than CompressedClassSpaceSize,
617 // in which case we just would not be able to fully commit the class space range.
618 //
619 // We still adjust CompressedClassSpaceSize to reasonable limits, mainly to
620 // save on reserved space, and to make ergnonomics less confusing.
621
622 // (aligned just for cleanliness:)
623 MaxMetaspaceSize = MAX2(align_down(MaxMetaspaceSize, commit_alignment()), commit_alignment());
624
625 if (UseCompressedClassPointers) {
626 // Let CCS size not be larger than 80% of MaxMetaspaceSize. Note that is
627 // grossly over-dimensioned for most usage scenarios; typical ratio of
628 // class space : non class space usage is about 1:6. With many small classes,
629 // it can get as low as 1:2. It is not a big deal though since ccs is only
630 // reserved and will be committed on demand only.
631 size_t max_ccs_size = MaxMetaspaceSize * 0.8;
632 size_t adjusted_ccs_size = MIN2(CompressedClassSpaceSize, max_ccs_size);
633
634 // CCS must be aligned to root chunk size, and be at least the size of one
635 // root chunk.
636 adjusted_ccs_size = align_up(adjusted_ccs_size, reserve_alignment());
637 adjusted_ccs_size = MAX2(adjusted_ccs_size, reserve_alignment());
638
639 // Note: re-adjusting may have us left with a CompressedClassSpaceSize
640 // larger than MaxMetaspaceSize for very small values of MaxMetaspaceSize.
641 // Lets just live with that, its not a big deal.
642
643 if (adjusted_ccs_size != CompressedClassSpaceSize) {
644 FLAG_SET_ERGO(CompressedClassSpaceSize, adjusted_ccs_size);
645 log_info(metaspace)("Setting CompressedClassSpaceSize to " SIZE_FORMAT ".",
646 CompressedClassSpaceSize);
647 }
648 }
649
650 // Set MetaspaceSize, MinMetaspaceExpansion and MaxMetaspaceExpansion
651 if (MetaspaceSize > MaxMetaspaceSize) {
652 MetaspaceSize = MaxMetaspaceSize;
653 }
654
655 MetaspaceSize = align_down_bounded(MetaspaceSize, commit_alignment());
656
657 assert(MetaspaceSize <= MaxMetaspaceSize, "MetaspaceSize should be limited by MaxMetaspaceSize");
658
659 MinMetaspaceExpansion = align_down_bounded(MinMetaspaceExpansion, commit_alignment());
660 MaxMetaspaceExpansion = align_down_bounded(MaxMetaspaceExpansion, commit_alignment());
661
662 }
663
664 void Metaspace::global_initialize() {
665 MetaspaceGC::initialize(); // <- since we do not prealloc init chunks anymore is this still needed?
666
667 metaspace::ChunkHeaderPool::initialize();
668
669 // If UseCompressedClassPointers=1, we have two cases:
670 // a) if CDS is active (either dump time or runtime), it will create the ccs
671 // for us, initialize it and set up CompressedKlassPointers encoding.
672 // Class space will be reserved above the mapped archives.
673 // b) if CDS is not active, we will create the ccs on our own. It will be
674 // placed above the java heap, since we assume it has been placed in low
675 // address regions. We may rethink this (see JDK-8244943). Failing that,
676 // it will be placed anywhere.
677
678 #if INCLUDE_CDS
679 // case (a)
680 if (DumpSharedSpaces) {
681 MetaspaceShared::initialize_dumptime_shared_and_meta_spaces();
682 } else if (UseSharedSpaces) {
683 // If any of the archived space fails to map, UseSharedSpaces
684 // is reset to false.
685 MetaspaceShared::initialize_runtime_shared_and_meta_spaces();
686 }
687
688 if (DynamicDumpSharedSpaces && !UseSharedSpaces) {
689 vm_exit_during_initialization("DynamicDumpSharedSpaces is unsupported when base CDS archive is not loaded", NULL);
690 }
691 #endif // INCLUDE_CDS
692
693 #ifdef _LP64
694
695 if (using_class_space() && !class_space_is_initialized()) {
696 assert(!UseSharedSpaces && !DumpSharedSpaces, "CDS should be off at this point");
697
698 // case (b)
699 ReservedSpace rs;
700
701 // If UseCompressedOops=1, java heap may have been placed in coops-friendly
702 // territory already (lower address regions), so we attempt to place ccs
703 // right above the java heap.
704 // If UseCompressedOops=0, the heap has been placed anywhere - probably in
705 // high memory regions. In that case, try to place ccs at the lowest allowed
706 // mapping address.
707 address base = UseCompressedOops ? CompressedOops::end() : (address)HeapBaseMinAddress;
708 base = align_up(base, Metaspace::reserve_alignment());
709
710 const size_t size = align_up(CompressedClassSpaceSize, Metaspace::reserve_alignment());
711 if (base != NULL) {
712 if (CompressedKlassPointers::is_valid_base(base)) {
713 rs = ReservedSpace(size, Metaspace::reserve_alignment(),
714 false /* large */, (char*)base);
715 }
716 }
717
718 // ...failing that, reserve anywhere, but let platform do optimized placement:
719 if (!rs.is_reserved()) {
720 rs = Metaspace::reserve_address_space_for_compressed_classes(size);
721 }
722
723 // ...failing that, give up.
724 if (!rs.is_reserved()) {
725 vm_exit_during_initialization(
726 err_msg("Could not allocate compressed class space: " SIZE_FORMAT " bytes",
727 CompressedClassSpaceSize));
728 }
729
730 // Initialize space
731 Metaspace::initialize_class_space(rs);
732
733 // Set up compressed class pointer encoding.
734 CompressedKlassPointers::initialize((address)rs.base(), rs.size());
735 }
736
737 #endif
738
739 // Initialize non-class virtual space list, and its chunk manager:
740 MetaspaceContext::initialize_nonclass_space_context();
741
742 _tracer = new MetaspaceTracer();
743
744 // We must prevent the very first address of the ccs from being used to store
745 // metadata, since that address would translate to a narrow pointer of 0, and the
746 // VM does not distinguish between "narrow 0 as in NULL" and "narrow 0 as in start
747 // of ccs".
748 // Before Elastic Metaspace that did not happen due to the fact that every Metachunk
749 // had a header and therefore could not allocate anything at offset 0.
750 #ifdef _LP64
751 if (using_class_space()) {
752 // The simplest way to fix this is to allocate a tiny dummy chunk right at the
753 // start of ccs and do not use it for anything.
754 MetaspaceContext::context_class()->cm()->get_chunk(metaspace::chunklevel::HIGHEST_CHUNK_LEVEL);
755 }
756 #endif
757
758 #ifdef _LP64
759 if (UseCompressedClassPointers) {
760 // Note: "cds" would be a better fit but keep this for backward compatibility.
761 LogTarget(Info, gc, metaspace) lt;
762 if (lt.is_enabled()) {
763 ResourceMark rm;
764 LogStream ls(lt);
765 CDS_ONLY(MetaspaceShared::print_on(&ls);)
766 Metaspace::print_compressed_class_space(&ls);
767 CompressedKlassPointers::print_mode(&ls);
768 }
769 }
770 #endif
771
772 }
773
774 void Metaspace::post_initialize() {
775 MetaspaceGC::post_initialize();
776 }
777
778 size_t Metaspace::max_allocation_word_size() {
779 const size_t max_overhead_words = metaspace::get_raw_word_size_for_requested_word_size(1);
780 return metaspace::chunklevel::MAX_CHUNK_WORD_SIZE - max_overhead_words;
781 }
782
783 MetaWord* Metaspace::allocate(ClassLoaderData* loader_data, size_t word_size,
784 MetaspaceObj::Type type, TRAPS) {
785 assert(word_size <= Metaspace::max_allocation_word_size(),
786 "allocation size too large (" SIZE_FORMAT ")", word_size);
787 assert(!_frozen, "sanity");
788 assert(!(DumpSharedSpaces && THREAD->is_VM_thread()), "sanity");
789
790 if (HAS_PENDING_EXCEPTION) {
791 assert(false, "Should not allocate with exception pending");
792 return NULL; // caller does a CHECK_NULL too
793 }
794
795 assert(loader_data != NULL, "Should never pass around a NULL loader_data. "
796 "ClassLoaderData::the_null_class_loader_data() should have been used.");
797
798 MetadataType mdtype = (type == MetaspaceObj::ClassType) ? ClassType : NonClassType;
799
800 // Try to allocate metadata.
801 MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
802
803 if (result == NULL) {
804 tracer()->report_metaspace_allocation_failure(loader_data, word_size, type, mdtype);
805
806 // Allocation failed.
807 if (is_init_completed()) {
808 // Only start a GC if the bootstrapping has completed.
809 // Try to clean out some heap memory and retry. This can prevent premature
810 // expansion of the metaspace.
811 result = Universe::heap()->satisfy_failed_metadata_allocation(loader_data, word_size, mdtype);
812 }
813 }
814
815 if (result == NULL) {
816 if (DumpSharedSpaces) {
817 // CDS dumping keeps loading classes, so if we hit an OOM we probably will keep hitting OOM.
818 // We should abort to avoid generating a potentially bad archive.
819 vm_exit_during_cds_dumping(err_msg("Failed allocating metaspace object type %s of size " SIZE_FORMAT ". CDS dump aborted.",
820 MetaspaceObj::type_name(type), word_size * BytesPerWord),
821 err_msg("Please increase MaxMetaspaceSize (currently " SIZE_FORMAT " bytes).", MaxMetaspaceSize));
822 }
823 report_metadata_oome(loader_data, word_size, type, mdtype, THREAD);
824 assert(HAS_PENDING_EXCEPTION, "sanity");
825 return NULL;
826 }
827
828 // Zero initialize.
829 Copy::fill_to_words((HeapWord*)result, word_size, 0);
830
831 log_trace(metaspace)("Metaspace::allocate: type %d return " PTR_FORMAT ".", (int)type, p2i(result));
832
833 return result;
834 }
835
836 void Metaspace::report_metadata_oome(ClassLoaderData* loader_data, size_t word_size, MetaspaceObj::Type type, MetadataType mdtype, TRAPS) {
837 tracer()->report_metadata_oom(loader_data, word_size, type, mdtype);
838
839 // If result is still null, we are out of memory.
840 Log(gc, metaspace, freelist, oom) log;
841 if (log.is_info()) {
842 log.info("Metaspace (%s) allocation failed for size " SIZE_FORMAT,
843 is_class_space_allocation(mdtype) ? "class" : "data", word_size);
844 ResourceMark rm;
845 if (log.is_debug()) {
846 if (loader_data->metaspace_or_null() != NULL) {
847 LogStream ls(log.debug());
848 loader_data->print_value_on(&ls);
849 }
850 }
851 LogStream ls(log.info());
852 // In case of an OOM, log out a short but still useful report.
853 MetaspaceUtils::print_basic_report(&ls, 0);
854 }
855
856 // TODO: this exception text may be wrong and misleading. This needs more thinking. See JDK-8252189.
857 bool out_of_compressed_class_space = false;
858 if (is_class_space_allocation(mdtype)) {
859 ClassLoaderMetaspace* metaspace = loader_data->metaspace_non_null();
860 out_of_compressed_class_space =
861 MetaspaceUtils::committed_bytes(Metaspace::ClassType) +
862 align_up(word_size * BytesPerWord, 4 * M) >
863 CompressedClassSpaceSize;
864 }
865
866 // -XX:+HeapDumpOnOutOfMemoryError and -XX:OnOutOfMemoryError support
867 const char* space_string = out_of_compressed_class_space ?
868 "Compressed class space" : "Metaspace";
869
870 report_java_out_of_memory(space_string);
871
872 if (JvmtiExport::should_post_resource_exhausted()) {
873 JvmtiExport::post_resource_exhausted(
874 JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR,
875 space_string);
876 }
877
878 if (!is_init_completed()) {
879 vm_exit_during_initialization("OutOfMemoryError", space_string);
880 }
881
882 if (out_of_compressed_class_space) {
883 THROW_OOP(Universe::out_of_memory_error_class_metaspace());
884 } else {
885 THROW_OOP(Universe::out_of_memory_error_metaspace());
886 }
887 }
888
889 const char* Metaspace::metadata_type_name(Metaspace::MetadataType mdtype) {
890 switch (mdtype) {
891 case Metaspace::ClassType: return "Class";
892 case Metaspace::NonClassType: return "Metadata";
893 default:
894 assert(false, "Got bad mdtype: %d", (int) mdtype);
895 return NULL;
896 }
897 }
898
899 void Metaspace::purge() {
900 ChunkManager* cm = ChunkManager::chunkmanager_nonclass();
901 if (cm != NULL) {
902 cm->purge();
903 }
904 if (using_class_space()) {
905 cm = ChunkManager::chunkmanager_class();
906 if (cm != NULL) {
907 cm->purge();
908 }
909 }
910 }
911
912 bool Metaspace::contains(const void* ptr) {
913 if (MetaspaceShared::is_in_shared_metaspace(ptr)) {
914 return true;
915 }
916 return contains_non_shared(ptr);
917 }
918
919 bool Metaspace::contains_non_shared(const void* ptr) {
920 if (using_class_space() && VirtualSpaceList::vslist_class()->contains((MetaWord*)ptr)) {
921 return true;
922 }
923
924 return VirtualSpaceList::vslist_nonclass()->contains((MetaWord*)ptr);
925 }