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.
22 *
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.hpp"
33 #include "memory/metaspaceShared.hpp"
34 #include "memory/metaspaceTracer.hpp"
35 #include "memory/metaspace/chunkHeaderPool.hpp"
36 #include "memory/metaspace/chunkManager.hpp"
37 #include "memory/metaspace/commitLimiter.hpp"
38 #include "memory/metaspace/metaspaceCommon.hpp"
39 #include "memory/metaspace/metaspaceContext.hpp"
40 #include "memory/metaspace/metaspaceEnums.hpp"
41 #include "memory/metaspace/metaspaceReport.hpp"
42 #include "memory/metaspace/metaspaceSizesSnapshot.hpp"
43 #include "memory/metaspace/runningCounters.hpp"
44 #include "memory/metaspace/settings.hpp"
45 #include "memory/metaspace/virtualSpaceList.hpp"
46 #include "memory/universe.hpp"
47 #include "oops/compressedOops.hpp"
48 #include "runtime/atomic.hpp"
49 #include "runtime/init.hpp"
50 #include "runtime/java.hpp"
51 #include "services/memTracker.hpp"
52 #include "utilities/copy.hpp"
53 #include "utilities/debug.hpp"
54 #include "utilities/formatBuffer.hpp"
55 #include "utilities/globalDefinitions.hpp"
56
57
58 using metaspace::ChunkManager;
59 using metaspace::CommitLimiter;
60 using metaspace::MetaspaceContext;
61 using metaspace::MetaspaceReporter;
62 using metaspace::RunningCounters;
63 using metaspace::VirtualSpaceList;
64
65
66 size_t MetaspaceUtils::used_words() {
67 return RunningCounters::used_words();
68 }
69
70 size_t MetaspaceUtils::used_words(Metaspace::MetadataType mdtype) {
71 return metaspace::is_class(mdtype) ? RunningCounters::used_words_class() : RunningCounters::used_words_nonclass();
72 }
73
74 size_t MetaspaceUtils::reserved_words() {
75 return RunningCounters::reserved_words();
76 }
77
78 size_t MetaspaceUtils::reserved_words(Metaspace::MetadataType mdtype) {
79 return metaspace::is_class(mdtype) ? RunningCounters::reserved_words_class() : RunningCounters::reserved_words_nonclass();
80 }
81
82 size_t MetaspaceUtils::committed_words() {
83 return RunningCounters::committed_words();
84 }
85
86 size_t MetaspaceUtils::committed_words(Metaspace::MetadataType mdtype) {
87 return metaspace::is_class(mdtype) ? RunningCounters::committed_words_class() : RunningCounters::committed_words_nonclass();
88 }
89
90
91
92 void MetaspaceUtils::print_metaspace_change(const metaspace::MetaspaceSizesSnapshot& pre_meta_values) {
93 const metaspace::MetaspaceSizesSnapshot meta_values;
94
95 // We print used and committed since these are the most useful at-a-glance vitals for Metaspace:
96 // - used tells you how much memory is actually used for metadata
97 // - committed tells you how much memory is committed for the purpose of metadata
98 // The difference between those two would be waste, which can have various forms (freelists,
99 // unused parts of committed chunks etc)
100 //
101 // Left out is reserved, since this is not as exciting as the first two values: for class space,
102 // it is a constant (to uninformed users, often confusingly large). For non-class space, it would
103 // be interesting since free chunks can be uncommitted, but for now it is left out.
104
105 if (Metaspace::using_class_space()) {
106 log_info(gc, metaspace)(HEAP_CHANGE_FORMAT" "
107 HEAP_CHANGE_FORMAT" "
108 HEAP_CHANGE_FORMAT,
109 HEAP_CHANGE_FORMAT_ARGS("Metaspace",
110 pre_meta_values.used(),
111 pre_meta_values.committed(),
112 meta_values.used(),
113 meta_values.committed()),
114 HEAP_CHANGE_FORMAT_ARGS("NonClass",
115 pre_meta_values.non_class_used(),
116 pre_meta_values.non_class_committed(),
117 meta_values.non_class_used(),
118 meta_values.non_class_committed()),
119 HEAP_CHANGE_FORMAT_ARGS("Class",
120 pre_meta_values.class_used(),
121 pre_meta_values.class_committed(),
122 meta_values.class_used(),
123 meta_values.class_committed()));
124 } else {
125 log_info(gc, metaspace)(HEAP_CHANGE_FORMAT,
126 HEAP_CHANGE_FORMAT_ARGS("Metaspace",
127 pre_meta_values.used(),
128 pre_meta_values.committed(),
129 meta_values.used(),
130 meta_values.committed()));
131 }
132 }
133
134 // This will print out a basic metaspace usage report but
135 // unlike print_report() is guaranteed not to lock or to walk the CLDG.
136 void MetaspaceUtils::print_basic_report(outputStream* out, size_t scale) {
137 MetaspaceReporter::print_basic_report(out, scale);
138 }
139
140 // Prints a report about the current metaspace state.
141 // Optional parts can be enabled via flags.
142 // Function will walk the CLDG and will lock the expand lock; if that is not
143 // convenient, use print_basic_report() instead.
144 void MetaspaceUtils::print_report(outputStream* out, size_t scale) {
145 const int flags =
146 MetaspaceReporter::rf_show_loaders |
147 MetaspaceReporter::rf_break_down_by_chunktype |
148 MetaspaceReporter::rf_show_classes;
149 MetaspaceReporter::print_report(out, scale, flags);
150 }
151
152 void MetaspaceUtils::print_on(outputStream* out) {
153
154 // Used from all GCs. It first prints out totals, then, separately, the class space portion.
155
156 out->print_cr(" Metaspace "
157 "used " SIZE_FORMAT "K, "
158 "committed " SIZE_FORMAT "K, "
159 "reserved " SIZE_FORMAT "K",
160 used_bytes()/K,
161 committed_bytes()/K,
162 reserved_bytes()/K);
163
164 if (Metaspace::using_class_space()) {
165 const Metaspace::MetadataType ct = Metaspace::ClassType;
166 out->print_cr(" class space "
167 "used " SIZE_FORMAT "K, "
168 "committed " SIZE_FORMAT "K, "
169 "reserved " SIZE_FORMAT "K",
170 used_bytes(ct)/K,
171 committed_bytes(ct)/K,
172 reserved_bytes(ct)/K);
173 }
174 }
175
176 #ifdef ASSERT
177 void MetaspaceUtils::verify(bool slow) {
178 if (Metaspace::initialized()) {
179
180 // Verify non-class chunkmanager...
181 ChunkManager* cm = ChunkManager::chunkmanager_nonclass();
182 cm->verify(slow);
183
184 // ... and space list.
185 VirtualSpaceList* vsl = VirtualSpaceList::vslist_nonclass();
186 vsl->verify(slow);
187
188 if (Metaspace::using_class_space()) {
189 // If we use compressed class pointers, verify class chunkmanager...
190 cm = ChunkManager::chunkmanager_class();
191 assert(cm != NULL, "Sanity");
192 cm->verify(slow);
193
194 // ... and class spacelist.
195 VirtualSpaceList* vsl = VirtualSpaceList::vslist_nonclass();
196 assert(vsl != NULL, "Sanity");
197 vsl->verify(slow);
198 }
199
200 }
201 }
202 #endif
203
204 ////////////////////////////////7
205 // MetaspaceGC methods
206
207 volatile size_t MetaspaceGC::_capacity_until_GC = 0;
208 uint MetaspaceGC::_shrink_factor = 0;
209
210 // VM_CollectForMetadataAllocation is the vm operation used to GC.
211 // Within the VM operation after the GC the attempt to allocate the metadata
212 // should succeed. If the GC did not free enough space for the metaspace
213 // allocation, the HWM is increased so that another virtualspace will be
214 // allocated for the metadata. With perm gen the increase in the perm
215 // gen had bounds, MinMetaspaceExpansion and MaxMetaspaceExpansion. The
216 // metaspace policy uses those as the small and large steps for the HWM.
217 //
218 // After the GC the compute_new_size() for MetaspaceGC is called to
219 // resize the capacity of the metaspaces. The current implementation
220 // is based on the flags MinMetaspaceFreeRatio and MaxMetaspaceFreeRatio used
221 // to resize the Java heap by some GC's. New flags can be implemented
222 // if really needed. MinMetaspaceFreeRatio is used to calculate how much
223 // free space is desirable in the metaspace capacity to decide how much
224 // to increase the HWM. MaxMetaspaceFreeRatio is used to decide how much
225 // free space is desirable in the metaspace capacity before decreasing
226 // the HWM.
227
228 // Calculate the amount to increase the high water mark (HWM).
229 // Increase by a minimum amount (MinMetaspaceExpansion) so that
230 // another expansion is not requested too soon. If that is not
231 // enough to satisfy the allocation, increase by MaxMetaspaceExpansion.
232 // If that is still not enough, expand by the size of the allocation
233 // plus some.
234 size_t MetaspaceGC::delta_capacity_until_GC(size_t bytes) {
235 size_t min_delta = MinMetaspaceExpansion;
236 size_t max_delta = MaxMetaspaceExpansion;
237 size_t delta = align_up(bytes, Metaspace::commit_alignment());
238
239 if (delta <= min_delta) {
240 delta = min_delta;
241 } else if (delta <= max_delta) {
242 // Don't want to hit the high water mark on the next
243 // allocation so make the delta greater than just enough
244 // for this allocation.
245 delta = max_delta;
246 } else {
247 // This allocation is large but the next ones are probably not
248 // so increase by the minimum.
249 delta = delta + min_delta;
250 }
251
252 assert_is_aligned(delta, Metaspace::commit_alignment());
253
254 return delta;
255 }
256
257 size_t MetaspaceGC::capacity_until_GC() {
258 size_t value = Atomic::load_acquire(&_capacity_until_GC);
259 assert(value >= MetaspaceSize, "Not initialized properly?");
260 return value;
261 }
262
263 // Try to increase the _capacity_until_GC limit counter by v bytes.
264 // Returns true if it succeeded. It may fail if either another thread
265 // concurrently increased the limit or the new limit would be larger
266 // than MaxMetaspaceSize.
267 // On success, optionally returns new and old metaspace capacity in
268 // new_cap_until_GC and old_cap_until_GC respectively.
269 // On error, optionally sets can_retry to indicate whether if there is
270 // actually enough space remaining to satisfy the request.
271 bool MetaspaceGC::inc_capacity_until_GC(size_t v, size_t* new_cap_until_GC, size_t* old_cap_until_GC, bool* can_retry) {
272 assert_is_aligned(v, Metaspace::commit_alignment());
273
274 size_t old_capacity_until_GC = _capacity_until_GC;
275 size_t new_value = old_capacity_until_GC + v;
276
277 if (new_value < old_capacity_until_GC) {
278 // The addition wrapped around, set new_value to aligned max value.
279 new_value = align_down(max_uintx, Metaspace::commit_alignment());
280 }
281
282 if (new_value > MaxMetaspaceSize) {
283 if (can_retry != NULL) {
284 *can_retry = false;
285 }
286 return false;
287 }
288
289 if (can_retry != NULL) {
290 *can_retry = true;
291 }
292 size_t prev_value = Atomic::cmpxchg(&_capacity_until_GC, old_capacity_until_GC, new_value);
293
294 if (old_capacity_until_GC != prev_value) {
295 return false;
296 }
297
298 if (new_cap_until_GC != NULL) {
299 *new_cap_until_GC = new_value;
300 }
301 if (old_cap_until_GC != NULL) {
302 *old_cap_until_GC = old_capacity_until_GC;
303 }
304 return true;
305 }
306
307 size_t MetaspaceGC::dec_capacity_until_GC(size_t v) {
308 assert_is_aligned(v, Metaspace::commit_alignment());
309
310 return Atomic::sub(&_capacity_until_GC, v);
311 }
312
313 void MetaspaceGC::initialize() {
314 // Set the high-water mark to MaxMetapaceSize during VM initializaton since
315 // we can't do a GC during initialization.
316 _capacity_until_GC = MaxMetaspaceSize;
317 }
318
319 void MetaspaceGC::post_initialize() {
320 // Reset the high-water mark once the VM initialization is done.
321 _capacity_until_GC = MAX2(MetaspaceUtils::committed_bytes(), MetaspaceSize);
322 }
323
324 bool MetaspaceGC::can_expand(size_t word_size, bool is_class) {
325 // Check if the compressed class space is full.
326 if (is_class && Metaspace::using_class_space()) {
327 size_t class_committed = MetaspaceUtils::committed_bytes(Metaspace::ClassType);
328 if (class_committed + word_size * BytesPerWord > CompressedClassSpaceSize) {
329 log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by " SIZE_FORMAT " words (CompressedClassSpaceSize = " SIZE_FORMAT " words)",
330 (is_class ? "class" : "non-class"), word_size, CompressedClassSpaceSize / sizeof(MetaWord));
331 return false;
332 }
333 }
334
335 // Check if the user has imposed a limit on the metaspace memory.
336 size_t committed_bytes = MetaspaceUtils::committed_bytes();
337 if (committed_bytes + word_size * BytesPerWord > MaxMetaspaceSize) {
338 log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by " SIZE_FORMAT " words (MaxMetaspaceSize = " SIZE_FORMAT " words)",
339 (is_class ? "class" : "non-class"), word_size, MaxMetaspaceSize / sizeof(MetaWord));
340 return false;
341 }
342
343 return true;
344 }
345
346 size_t MetaspaceGC::allowed_expansion() {
347 size_t committed_bytes = MetaspaceUtils::committed_bytes();
348 size_t capacity_until_gc = capacity_until_GC();
349
350 assert(capacity_until_gc >= committed_bytes,
351 "capacity_until_gc: " SIZE_FORMAT " < committed_bytes: " SIZE_FORMAT,
352 capacity_until_gc, committed_bytes);
353
354 size_t left_until_max = MaxMetaspaceSize - committed_bytes;
355 size_t left_until_GC = capacity_until_gc - committed_bytes;
356 size_t left_to_commit = MIN2(left_until_GC, left_until_max);
357 log_trace(gc, metaspace, freelist)("allowed expansion words: " SIZE_FORMAT
358 " (left_until_max: " SIZE_FORMAT ", left_until_GC: " SIZE_FORMAT ".",
359 left_to_commit / BytesPerWord, left_until_max / BytesPerWord, left_until_GC / BytesPerWord);
360
361 return left_to_commit / BytesPerWord;
362 }
363
364 void MetaspaceGC::compute_new_size() {
365 assert(_shrink_factor <= 100, "invalid shrink factor");
366 uint current_shrink_factor = _shrink_factor;
367 _shrink_factor = 0;
368
369 // Using committed_bytes() for used_after_gc is an overestimation, since the
370 // chunk free lists are included in committed_bytes() and the memory in an
371 // un-fragmented chunk free list is available for future allocations.
372 // However, if the chunk free lists becomes fragmented, then the memory may
373 // not be available for future allocations and the memory is therefore "in use".
374 // Including the chunk free lists in the definition of "in use" is therefore
375 // necessary. Not including the chunk free lists can cause capacity_until_GC to
376 // shrink below committed_bytes() and this has caused serious bugs in the past.
377 const size_t used_after_gc = MetaspaceUtils::committed_bytes();
378 const size_t capacity_until_GC = MetaspaceGC::capacity_until_GC();
379
380 const double minimum_free_percentage = MinMetaspaceFreeRatio / 100.0;
381 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
382
383 const double min_tmp = used_after_gc / maximum_used_percentage;
384 size_t minimum_desired_capacity =
385 (size_t)MIN2(min_tmp, double(MaxMetaspaceSize));
386 // Don't shrink less than the initial generation size
387 minimum_desired_capacity = MAX2(minimum_desired_capacity,
388 MetaspaceSize);
389
390 log_trace(gc, metaspace)("MetaspaceGC::compute_new_size: ");
391 log_trace(gc, metaspace)(" minimum_free_percentage: %6.2f maximum_used_percentage: %6.2f",
392 minimum_free_percentage, maximum_used_percentage);
393 log_trace(gc, metaspace)(" used_after_gc : %6.1fKB", used_after_gc / (double) K);
394
395
396 size_t shrink_bytes = 0;
397 if (capacity_until_GC < minimum_desired_capacity) {
398 // If we have less capacity below the metaspace HWM, then
399 // increment the HWM.
400 size_t expand_bytes = minimum_desired_capacity - capacity_until_GC;
401 expand_bytes = align_up(expand_bytes, Metaspace::commit_alignment());
402 // Don't expand unless it's significant
403 if (expand_bytes >= MinMetaspaceExpansion) {
404 size_t new_capacity_until_GC = 0;
405 bool succeeded = MetaspaceGC::inc_capacity_until_GC(expand_bytes, &new_capacity_until_GC);
406 assert(succeeded, "Should always succesfully increment HWM when at safepoint");
407
408 Metaspace::tracer()->report_gc_threshold(capacity_until_GC,
409 new_capacity_until_GC,
410 MetaspaceGCThresholdUpdater::ComputeNewSize);
411 log_trace(gc, metaspace)(" expanding: minimum_desired_capacity: %6.1fKB expand_bytes: %6.1fKB MinMetaspaceExpansion: %6.1fKB new metaspace HWM: %6.1fKB",
412 minimum_desired_capacity / (double) K,
413 expand_bytes / (double) K,
414 MinMetaspaceExpansion / (double) K,
415 new_capacity_until_GC / (double) K);
416 }
417 return;
418 }
419
420 // No expansion, now see if we want to shrink
421 // We would never want to shrink more than this
422 assert(capacity_until_GC >= minimum_desired_capacity,
423 SIZE_FORMAT " >= " SIZE_FORMAT,
424 capacity_until_GC, minimum_desired_capacity);
425 size_t max_shrink_bytes = capacity_until_GC - minimum_desired_capacity;
426
427 // Should shrinking be considered?
428 if (MaxMetaspaceFreeRatio < 100) {
429 const double maximum_free_percentage = MaxMetaspaceFreeRatio / 100.0;
430 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
431 const double max_tmp = used_after_gc / minimum_used_percentage;
432 size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(MaxMetaspaceSize));
433 maximum_desired_capacity = MAX2(maximum_desired_capacity,
434 MetaspaceSize);
435 log_trace(gc, metaspace)(" maximum_free_percentage: %6.2f minimum_used_percentage: %6.2f",
436 maximum_free_percentage, minimum_used_percentage);
437 log_trace(gc, metaspace)(" minimum_desired_capacity: %6.1fKB maximum_desired_capacity: %6.1fKB",
438 minimum_desired_capacity / (double) K, maximum_desired_capacity / (double) K);
439
440 assert(minimum_desired_capacity <= maximum_desired_capacity,
441 "sanity check");
442
443 if (capacity_until_GC > maximum_desired_capacity) {
444 // Capacity too large, compute shrinking size
445 shrink_bytes = capacity_until_GC - maximum_desired_capacity;
446 // We don't want shrink all the way back to initSize if people call
447 // System.gc(), because some programs do that between "phases" and then
448 // we'd just have to grow the heap up again for the next phase. So we
449 // damp the shrinking: 0% on the first call, 10% on the second call, 40%
450 // on the third call, and 100% by the fourth call. But if we recompute
451 // size without shrinking, it goes back to 0%.
452 shrink_bytes = shrink_bytes / 100 * current_shrink_factor;
453
454 shrink_bytes = align_down(shrink_bytes, Metaspace::commit_alignment());
455
456 assert(shrink_bytes <= max_shrink_bytes,
457 "invalid shrink size " SIZE_FORMAT " not <= " SIZE_FORMAT,
458 shrink_bytes, max_shrink_bytes);
459 if (current_shrink_factor == 0) {
460 _shrink_factor = 10;
461 } else {
462 _shrink_factor = MIN2(current_shrink_factor * 4, (uint) 100);
463 }
464 log_trace(gc, metaspace)(" shrinking: initThreshold: %.1fK maximum_desired_capacity: %.1fK",
465 MetaspaceSize / (double) K, maximum_desired_capacity / (double) K);
466 log_trace(gc, metaspace)(" shrink_bytes: %.1fK current_shrink_factor: %d new shrink factor: %d MinMetaspaceExpansion: %.1fK",
467 shrink_bytes / (double) K, current_shrink_factor, _shrink_factor, MinMetaspaceExpansion / (double) K);
468 }
469 }
470
471 // Don't shrink unless it's significant
472 if (shrink_bytes >= MinMetaspaceExpansion &&
473 ((capacity_until_GC - shrink_bytes) >= MetaspaceSize)) {
474 size_t new_capacity_until_GC = MetaspaceGC::dec_capacity_until_GC(shrink_bytes);
475 Metaspace::tracer()->report_gc_threshold(capacity_until_GC,
476 new_capacity_until_GC,
477 MetaspaceGCThresholdUpdater::ComputeNewSize);
478 }
479 }
480
481
482
483 ////// Metaspace methods /////
484
485 const MetaspaceTracer* Metaspace::_tracer = NULL;
486
487 DEBUG_ONLY(bool Metaspace::_frozen = false;)
488
489 bool Metaspace::initialized() {
490 return metaspace::MetaspaceContext::context_nonclass() != NULL &&
491 (using_class_space() ? metaspace::MetaspaceContext::context_class() != NULL : true);
492 }
493
494 #ifdef _LP64
495
496 void Metaspace::print_compressed_class_space(outputStream* st) {
497 if (VirtualSpaceList::vslist_class() != NULL) {
498 MetaWord* base = VirtualSpaceList::vslist_class()->base_of_first_node();
499 size_t size = VirtualSpaceList::vslist_class()->word_size_of_first_node();
500 MetaWord* top = base + size;
501 st->print("Compressed class space mapped at: " PTR_FORMAT "-" PTR_FORMAT ", reserved size: " SIZE_FORMAT,
502 p2i(base), p2i(top), (top - base) * BytesPerWord);
503 st->cr();
504 }
505 }
506
507 // Given a prereserved space, use that to set up the compressed class space list.
508 void Metaspace::initialize_class_space(ReservedSpace rs) {
509 assert(rs.size() >= CompressedClassSpaceSize,
510 SIZE_FORMAT " != " SIZE_FORMAT, rs.size(), CompressedClassSpaceSize);
511 assert(using_class_space(), "Must be using class space");
512
513 assert(rs.size() == CompressedClassSpaceSize, SIZE_FORMAT " != " SIZE_FORMAT,
514 rs.size(), CompressedClassSpaceSize);
515 assert(is_aligned(rs.base(), Metaspace::reserve_alignment()) &&
516 is_aligned(rs.size(), Metaspace::reserve_alignment()),
517 "wrong alignment");
518
519 MetaspaceContext::initialize_class_space_context(rs);
520
521 // This does currently not work because rs may be the result of a split
522 // operation and NMT seems not to be able to handle splits.
523 // Will be fixed with JDK-8243535.
524 // MemTracker::record_virtual_memory_type((address)rs.base(), mtClass);
525
526 }
527
528 // Returns true if class space has been setup (initialize_class_space).
529 bool Metaspace::class_space_is_initialized() {
530 return MetaspaceContext::context_class() != NULL;
531 }
532
533 // Reserve a range of memory at an address suitable for en/decoding narrow
534 // Klass pointers (see: CompressedClassPointers::is_valid_base()).
535 // The returned address shall both be suitable as a compressed class pointers
536 // base, and aligned to Metaspace::reserve_alignment (which is equal to or a
537 // multiple of allocation granularity).
538 // On error, returns an unreserved space.
539 ReservedSpace Metaspace::reserve_address_space_for_compressed_classes(size_t size) {
540
541 #ifdef AARCH64
542 const size_t alignment = Metaspace::reserve_alignment();
543
544 // AArch64: Try to align metaspace so that we can decode a compressed
545 // klass with a single MOVK instruction. We can do this iff the
546 // compressed class base is a multiple of 4G.
547 // Additionally, above 32G, ensure the lower LogKlassAlignmentInBytes bits
548 // of the upper 32-bits of the address are zero so we can handle a shift
549 // when decoding.
550
551 static const struct {
552 address from;
553 address to;
554 size_t increment;
555 } search_ranges[] = {
556 { (address)(4*G), (address)(32*G), 4*G, },
557 { (address)(32*G), (address)(1024*G), (4 << LogKlassAlignmentInBytes) * G },
558 { NULL, NULL, 0 }
559 };
560
561 for (int i = 0; search_ranges[i].from != NULL; i ++) {
562 address a = search_ranges[i].from;
563 assert(CompressedKlassPointers::is_valid_base(a), "Sanity");
564 while (a < search_ranges[i].to) {
565 ReservedSpace rs(size, Metaspace::reserve_alignment(),
566 false /*large_pages*/, (char*)a);
567 if (rs.is_reserved()) {
568 assert(a == (address)rs.base(), "Sanity");
569 return rs;
570 }
571 a += search_ranges[i].increment;
572 }
573 }
574
575 // Note: on AARCH64, if the code above does not find any good placement, we
576 // have no recourse. We return an empty space and the VM will exit.
577 return ReservedSpace();
578 #else
579 // Default implementation: Just reserve anywhere.
580 return ReservedSpace(size, Metaspace::reserve_alignment(), false, (char*)NULL);
581 #endif // AARCH64
582 }
583
584 #endif // _LP64
585
586
587 size_t Metaspace::reserve_alignment_words() {
588 return metaspace::Settings::virtual_space_node_reserve_alignment_words();
589 }
590
591 size_t Metaspace::commit_alignment_words() {
592 return metaspace::Settings::commit_granule_words();
593 }
594
595 void Metaspace::ergo_initialize() {
596
597 // Must happen before using any setting from Settings::---
598 metaspace::Settings::ergo_initialize();
599
600 // MaxMetaspaceSize and CompressedClassSpaceSize:
601 //
602 // MaxMetaspaceSize is the maximum size, in bytes, of memory we are allowed
603 // to commit for the Metaspace.
604 // It is just a number; a limit we compare against before committing. It
605 // does not have to be aligned to anything.
606 // It gets used as compare value in class CommitLimiter.
607 // It is set to max_uintx in globals.hpp by default, so by default it does
608 // not limit anything.
609 //
610 // CompressedClassSpaceSize is the size, in bytes, of the address range we
611 // pre-reserve for the compressed class space (if we use class space).
612 // This size has to be aligned to the metaspace reserve alignment (to the
613 // size of a root chunk). It gets aligned up from whatever value the caller
614 // gave us to the next multiple of root chunk size.
615 //
616 // Note: Strictly speaking MaxMetaspaceSize and CompressedClassSpaceSize have
617 // very little to do with each other. The notion often encountered:
618 // MaxMetaspaceSize = CompressedClassSpaceSize + <non-class metadata size>
619 // is subtly wrong: MaxMetaspaceSize can besmaller than CompressedClassSpaceSize,
620 // in which case we just would not be able to fully commit the class space range.
621 //
622 // We still adjust CompressedClassSpaceSize to reasonable limits, mainly to
623 // save on reserved space, and to make ergnonomics less confusing.
624
625 // (aligned just for cleanliness:)
626 MaxMetaspaceSize = MAX2(align_down(MaxMetaspaceSize, commit_alignment()), commit_alignment());
627
628 if (UseCompressedClassPointers) {
629 // Let CCS size not be larger than 80% of MaxMetaspaceSize. Note that is
630 // grossly over-dimensioned for most usage scenarios; typical ratio of
631 // class space : non class space usage is about 1:6. With many small classes,
632 // it can get as low as 1:2. It is not a big deal though since ccs is only
633 // reserved and will be committed on demand only.
634 size_t max_ccs_size = MaxMetaspaceSize * 0.8;
635 size_t adjusted_ccs_size = MIN2(CompressedClassSpaceSize, max_ccs_size);
636
637 // CCS must be aligned to root chunk size, and be at least the size of one
638 // root chunk.
639 adjusted_ccs_size = align_up(adjusted_ccs_size, reserve_alignment());
640 adjusted_ccs_size = MAX2(adjusted_ccs_size, reserve_alignment());
641
642 // Note: re-adjusting may have us left with a CompressedClassSpaceSize
643 // larger than MaxMetaspaceSize for very small values of MaxMetaspaceSize.
644 // Lets just live with that, its not a big deal.
645
646 if (adjusted_ccs_size != CompressedClassSpaceSize) {
647 FLAG_SET_ERGO(CompressedClassSpaceSize, adjusted_ccs_size);
648 log_info(metaspace)("Setting CompressedClassSpaceSize to " SIZE_FORMAT ".",
649 CompressedClassSpaceSize);
650 }
651 }
652
653 // Set MetaspaceSize, MinMetaspaceExpansion and MaxMetaspaceExpansion
654 if (MetaspaceSize > MaxMetaspaceSize) {
655 MetaspaceSize = MaxMetaspaceSize;
656 }
657
658 MetaspaceSize = align_down_bounded(MetaspaceSize, commit_alignment());
659
660 assert(MetaspaceSize <= MaxMetaspaceSize, "MetaspaceSize should be limited by MaxMetaspaceSize");
661
662 MinMetaspaceExpansion = align_down_bounded(MinMetaspaceExpansion, commit_alignment());
663 MaxMetaspaceExpansion = align_down_bounded(MaxMetaspaceExpansion, commit_alignment());
664
665 }
666
667 void Metaspace::global_initialize() {
668 MetaspaceGC::initialize(); // <- since we do not prealloc init chunks anymore is this still needed?
669
670 metaspace::ChunkHeaderPool::initialize();
671
672 // If UseCompressedClassPointers=1, we have two cases:
673 // a) if CDS is active (either dump time or runtime), it will create the ccs
674 // for us, initialize it and set up CompressedKlassPointers encoding.
675 // Class space will be reserved above the mapped archives.
676 // b) if CDS is not active, we will create the ccs on our own. It will be
677 // placed above the java heap, since we assume it has been placed in low
678 // address regions. We may rethink this (see JDK-8244943). Failing that,
679 // it will be placed anywhere.
680
681 #if INCLUDE_CDS
682 // case (a)
683 if (DumpSharedSpaces) {
684 MetaspaceShared::initialize_dumptime_shared_and_meta_spaces();
685 } else if (UseSharedSpaces) {
686 // If any of the archived space fails to map, UseSharedSpaces
687 // is reset to false.
688 MetaspaceShared::initialize_runtime_shared_and_meta_spaces();
689 }
690
691 if (DynamicDumpSharedSpaces && !UseSharedSpaces) {
692 vm_exit_during_initialization("DynamicDumpSharedSpaces is unsupported when base CDS archive is not loaded", NULL);
693 }
694 #endif // INCLUDE_CDS
695
696 #ifdef _LP64
697
698 if (using_class_space() && !class_space_is_initialized()) {
699 assert(!UseSharedSpaces && !DumpSharedSpaces, "CDS should be off at this point");
700
701 // case (b)
702 ReservedSpace rs;
703
704 // If UseCompressedOops=1, java heap may have been placed in coops-friendly
705 // territory already (lower address regions), so we attempt to place ccs
706 // right above the java heap.
707 // If UseCompressedOops=0, the heap has been placed anywhere - probably in
708 // high memory regions. In that case, try to place ccs at the lowest allowed
709 // mapping address.
710 address base = UseCompressedOops ? CompressedOops::end() : (address)HeapBaseMinAddress;
711 base = align_up(base, Metaspace::reserve_alignment());
712
713 const size_t size = align_up(CompressedClassSpaceSize, Metaspace::reserve_alignment());
714 if (base != NULL) {
715 if (CompressedKlassPointers::is_valid_base(base)) {
716 rs = ReservedSpace(size, Metaspace::reserve_alignment(),
717 false /* large */, (char*)base);
718 }
719 }
720
721 // ...failing that, reserve anywhere, but let platform do optimized placement:
722 if (!rs.is_reserved()) {
723 rs = Metaspace::reserve_address_space_for_compressed_classes(size);
724 }
725
726 // ...failing that, give up.
727 if (!rs.is_reserved()) {
728 vm_exit_during_initialization(
729 err_msg("Could not allocate compressed class space: " SIZE_FORMAT " bytes",
730 CompressedClassSpaceSize));
731 }
732
733 // Initialize space
734 Metaspace::initialize_class_space(rs);
735
736 // Set up compressed class pointer encoding.
737 CompressedKlassPointers::initialize((address)rs.base(), rs.size());
738 }
739
740 #endif
741
742 // Initialize non-class virtual space list, and its chunk manager:
743 MetaspaceContext::initialize_nonclass_space_context();
744
745 _tracer = new MetaspaceTracer();
746
747 // We must prevent the very first address of the ccs from being used to store
748 // metadata, since that address would translate to a narrow pointer of 0, and the
749 // VM does not distinguish between "narrow 0 as in NULL" and "narrow 0 as in start
750 // of ccs".
751 // Before Elastic Metaspace that did not happen due to the fact that every Metachunk
752 // had a header and therefore could not allocate anything at offset 0.
753 #ifdef _LP64
754 if (using_class_space()) {
755 // The simplest way to fix this is to allocate a tiny dummy chunk right at the
756 // start of ccs and do not use it for anything.
757 MetaspaceContext::context_class()->cm()->get_chunk(metaspace::chunklevel::HIGHEST_CHUNK_LEVEL);
758 }
759 #endif
760
761 #ifdef _LP64
762 if (UseCompressedClassPointers) {
763 // Note: "cds" would be a better fit but keep this for backward compatibility.
764 LogTarget(Info, gc, metaspace) lt;
765 if (lt.is_enabled()) {
766 ResourceMark rm;
767 LogStream ls(lt);
768 CDS_ONLY(MetaspaceShared::print_on(&ls);)
769 Metaspace::print_compressed_class_space(&ls);
770 CompressedKlassPointers::print_mode(&ls);
771 }
772 }
773 #endif
774
775 }
776
777 void Metaspace::post_initialize() {
778 MetaspaceGC::post_initialize();
779 }
780
781 size_t Metaspace::max_allocation_word_size() {
782 const size_t max_overhead_words = metaspace::get_raw_word_size_for_requested_word_size(1);
783 return metaspace::chunklevel::MAX_CHUNK_WORD_SIZE - max_overhead_words;
784 }
785
786 MetaWord* Metaspace::allocate(ClassLoaderData* loader_data, size_t word_size,
787 MetaspaceObj::Type type, TRAPS) {
788 assert(word_size <= Metaspace::max_allocation_word_size(),
789 "allocation size too large (" SIZE_FORMAT ")", word_size);
790 assert(!_frozen, "sanity");
791 assert(!(DumpSharedSpaces && THREAD->is_VM_thread()), "sanity");
792
793 if (HAS_PENDING_EXCEPTION) {
794 assert(false, "Should not allocate with exception pending");
795 return NULL; // caller does a CHECK_NULL too
796 }
797
798 assert(loader_data != NULL, "Should never pass around a NULL loader_data. "
799 "ClassLoaderData::the_null_class_loader_data() should have been used.");
800
801 Metaspace::MetadataType mdtype = (type == MetaspaceObj::ClassType) ? Metaspace::ClassType : Metaspace::NonClassType;
802
803 // Try to allocate metadata.
804 MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
805
806 if (result == NULL) {
807 tracer()->report_metaspace_allocation_failure(loader_data, word_size, type, mdtype);
808
809 // Allocation failed.
810 if (is_init_completed()) {
811 // Only start a GC if the bootstrapping has completed.
812 // Try to clean out some heap memory and retry. This can prevent premature
813 // expansion of the metaspace.
814 result = Universe::heap()->satisfy_failed_metadata_allocation(loader_data, word_size, mdtype);
815 }
816 }
817
818 if (result == NULL) {
819 if (DumpSharedSpaces) {
820 // CDS dumping keeps loading classes, so if we hit an OOM we probably will keep hitting OOM.
821 // We should abort to avoid generating a potentially bad archive.
822 vm_exit_during_cds_dumping(err_msg("Failed allocating metaspace object type %s of size " SIZE_FORMAT ". CDS dump aborted.",
823 MetaspaceObj::type_name(type), word_size * BytesPerWord),
824 err_msg("Please increase MaxMetaspaceSize (currently " SIZE_FORMAT " bytes).", MaxMetaspaceSize));
825 }
826 report_metadata_oome(loader_data, word_size, type, mdtype, THREAD);
827 assert(HAS_PENDING_EXCEPTION, "sanity");
828 return NULL;
829 }
830
831 // Zero initialize.
832 Copy::fill_to_words((HeapWord*)result, word_size, 0);
833
834 log_trace(metaspace)("Metaspace::allocate: type %d return " PTR_FORMAT ".", (int)type, p2i(result));
835
836 return result;
837 }
838
839 void Metaspace::report_metadata_oome(ClassLoaderData* loader_data, size_t word_size, MetaspaceObj::Type type, MetadataType mdtype, TRAPS) {
840 tracer()->report_metadata_oom(loader_data, word_size, type, mdtype);
841
842 // If result is still null, we are out of memory.
843 Log(gc, metaspace, freelist, oom) log;
844 if (log.is_info()) {
845 log.info("Metaspace (%s) allocation failed for size " SIZE_FORMAT,
846 metaspace::is_class(mdtype) ? "class" : "data", word_size);
847 ResourceMark rm;
848 if (log.is_debug()) {
849 if (loader_data->metaspace_or_null() != NULL) {
850 LogStream ls(log.debug());
851 loader_data->print_value_on(&ls);
852 }
853 }
854 LogStream ls(log.info());
855 // In case of an OOM, log out a short but still useful report.
856 MetaspaceUtils::print_basic_report(&ls, 0);
857 }
858
859 // Which limit did we hit? CompressedClassSpaceSize or MaxMetaspaceSize?
860 bool out_of_compressed_class_space = false;
861 if (metaspace::is_class(mdtype)) {
862 ClassLoaderMetaspace* metaspace = loader_data->metaspace_non_null();
863 out_of_compressed_class_space =
864 MetaspaceUtils::committed_bytes(Metaspace::ClassType) +
865 // TODO: Okay this is just cheesy.
866 // Of course this may fail and return incorrect results.
867 // Think this over - we need some clean way to remember which limit
868 // exactly we hit during an allocation. Some sort of allocation context structure?
869 align_up(word_size * BytesPerWord, 4 * M) >
870 CompressedClassSpaceSize;
871 }
872
873 // -XX:+HeapDumpOnOutOfMemoryError and -XX:OnOutOfMemoryError support
874 const char* space_string = out_of_compressed_class_space ?
875 "Compressed class space" : "Metaspace";
876
877 report_java_out_of_memory(space_string);
878
879 if (JvmtiExport::should_post_resource_exhausted()) {
880 JvmtiExport::post_resource_exhausted(
881 JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR,
882 space_string);
883 }
884
885 if (!is_init_completed()) {
886 vm_exit_during_initialization("OutOfMemoryError", space_string);
887 }
888
889 if (out_of_compressed_class_space) {
890 THROW_OOP(Universe::out_of_memory_error_class_metaspace());
891 } else {
892 THROW_OOP(Universe::out_of_memory_error_metaspace());
893 }
894 }
895
896 void Metaspace::purge() {
897 ChunkManager* cm = ChunkManager::chunkmanager_nonclass();
898 if (cm != NULL) {
899 cm->purge();
900 }
901 if (using_class_space()) {
902 cm = ChunkManager::chunkmanager_class();
903 if (cm != NULL) {
904 cm->purge();
905 }
906 }
907 }
908
909 bool Metaspace::contains(const void* ptr) {
910 if (MetaspaceShared::is_in_shared_metaspace(ptr)) {
911 return true;
912 }
913 return contains_non_shared(ptr);
914 }
915
916 bool Metaspace::contains_non_shared(const void* ptr) {
917 if (using_class_space() && VirtualSpaceList::vslist_class()->contains((MetaWord*)ptr)) {
918 return true;
919 }
920
921 return VirtualSpaceList::vslist_nonclass()->contains((MetaWord*)ptr);
922 }