1 /*
2 * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2013, 2022, Red Hat, Inc. 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 "memory/allocation.hpp"
28 #include "memory/universe.hpp"
29
30 #include "gc/shared/gcArguments.hpp"
31 #include "gc/shared/gcTimer.hpp"
32 #include "gc/shared/gcTraceTime.inline.hpp"
33 #include "gc/shared/locationPrinter.inline.hpp"
34 #include "gc/shared/memAllocator.hpp"
35 #include "gc/shared/plab.hpp"
36 #include "gc/shared/tlab_globals.hpp"
37
38 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
39 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
40 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
41 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
42 #include "gc/shenandoah/shenandoahConcurrentMark.hpp"
43 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
44 #include "gc/shenandoah/shenandoahControlThread.hpp"
45 #include "gc/shenandoah/shenandoahFreeSet.hpp"
46 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
47 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
48 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
49 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
50 #include "gc/shenandoah/shenandoahInitLogger.hpp"
51 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
52 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
53 #include "gc/shenandoah/shenandoahMetrics.hpp"
54 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
55 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
56 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
57 #include "gc/shenandoah/shenandoahPadding.hpp"
58 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
59 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
60 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
61 #include "gc/shenandoah/shenandoahSTWMark.hpp"
62 #include "gc/shenandoah/shenandoahUtils.hpp"
63 #include "gc/shenandoah/shenandoahVerifier.hpp"
64 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
65 #include "gc/shenandoah/shenandoahVMOperations.hpp"
66 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
67 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
68 #include "gc/shenandoah/mode/shenandoahIUMode.hpp"
69 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
70 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
71 #if INCLUDE_JFR
72 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
73 #endif
74
75 #include "classfile/systemDictionary.hpp"
76 #include "code/codeCache.hpp"
77 #include "memory/classLoaderMetaspace.hpp"
78 #include "memory/metaspaceUtils.hpp"
79 #include "oops/compressedOops.inline.hpp"
80 #include "prims/jvmtiTagMap.hpp"
81 #include "runtime/atomic.hpp"
82 #include "runtime/globals.hpp"
83 #include "runtime/interfaceSupport.inline.hpp"
84 #include "runtime/java.hpp"
85 #include "runtime/orderAccess.hpp"
86 #include "runtime/safepointMechanism.hpp"
87 #include "runtime/vmThread.hpp"
88 #include "services/mallocTracker.hpp"
89 #include "services/memTracker.hpp"
90 #include "utilities/events.hpp"
91 #include "utilities/powerOfTwo.hpp"
92
93 class ShenandoahPretouchHeapTask : public WorkerTask {
94 private:
95 ShenandoahRegionIterator _regions;
96 const size_t _page_size;
97 public:
98 ShenandoahPretouchHeapTask(size_t page_size) :
99 WorkerTask("Shenandoah Pretouch Heap"),
100 _page_size(page_size) {}
101
102 virtual void work(uint worker_id) {
103 ShenandoahHeapRegion* r = _regions.next();
104 while (r != nullptr) {
105 if (r->is_committed()) {
106 os::pretouch_memory(r->bottom(), r->end(), _page_size);
107 }
108 r = _regions.next();
109 }
110 }
111 };
112
113 class ShenandoahPretouchBitmapTask : public WorkerTask {
114 private:
115 ShenandoahRegionIterator _regions;
116 char* _bitmap_base;
117 const size_t _bitmap_size;
118 const size_t _page_size;
119 public:
120 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
121 WorkerTask("Shenandoah Pretouch Bitmap"),
122 _bitmap_base(bitmap_base),
123 _bitmap_size(bitmap_size),
124 _page_size(page_size) {}
125
126 virtual void work(uint worker_id) {
127 ShenandoahHeapRegion* r = _regions.next();
128 while (r != nullptr) {
129 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
130 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
131 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
132
133 if (r->is_committed()) {
134 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
135 }
136
137 r = _regions.next();
138 }
139 }
140 };
141
142 jint ShenandoahHeap::initialize() {
143 //
144 // Figure out heap sizing
145 //
146
147 size_t init_byte_size = InitialHeapSize;
148 size_t min_byte_size = MinHeapSize;
149 size_t max_byte_size = MaxHeapSize;
150 size_t heap_alignment = HeapAlignment;
151
152 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
153
154 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
155 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
156
157 _num_regions = ShenandoahHeapRegion::region_count();
158 assert(_num_regions == (max_byte_size / reg_size_bytes),
159 "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT,
160 _num_regions, max_byte_size, reg_size_bytes);
161
162 // Now we know the number of regions, initialize the heuristics.
163 initialize_heuristics();
164
165 size_t num_committed_regions = init_byte_size / reg_size_bytes;
166 num_committed_regions = MIN2(num_committed_regions, _num_regions);
167 assert(num_committed_regions <= _num_regions, "sanity");
168 _initial_size = num_committed_regions * reg_size_bytes;
169
170 size_t num_min_regions = min_byte_size / reg_size_bytes;
171 num_min_regions = MIN2(num_min_regions, _num_regions);
172 assert(num_min_regions <= _num_regions, "sanity");
173 _minimum_size = num_min_regions * reg_size_bytes;
174
175 // Default to max heap size.
176 _soft_max_size = _num_regions * reg_size_bytes;
177
178 _committed = _initial_size;
179
180 size_t heap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
181 size_t bitmap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
182 size_t region_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
183
184 //
185 // Reserve and commit memory for heap
186 //
187
188 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
189 initialize_reserved_region(heap_rs);
190 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
191 _heap_region_special = heap_rs.special();
192
193 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
194 "Misaligned heap: " PTR_FORMAT, p2i(base()));
195
196 #if SHENANDOAH_OPTIMIZED_MARKTASK
197 // The optimized ShenandoahMarkTask takes some bits away from the full object bits.
198 // Fail if we ever attempt to address more than we can.
199 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) {
200 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
201 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
202 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
203 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable());
204 vm_exit_during_initialization("Fatal Error", buf);
205 }
206 #endif
207
208 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
209 if (!_heap_region_special) {
210 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
211 "Cannot commit heap memory");
212 }
213
214 //
215 // Reserve and commit memory for bitmap(s)
216 //
217
218 _bitmap_size = ShenandoahMarkBitMap::compute_size(heap_rs.size());
219 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
220
221 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor();
222
223 guarantee(bitmap_bytes_per_region != 0,
224 "Bitmap bytes per region should not be zero");
225 guarantee(is_power_of_2(bitmap_bytes_per_region),
226 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
227
228 if (bitmap_page_size > bitmap_bytes_per_region) {
229 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
230 _bitmap_bytes_per_slice = bitmap_page_size;
231 } else {
232 _bitmap_regions_per_slice = 1;
233 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
234 }
235
236 guarantee(_bitmap_regions_per_slice >= 1,
237 "Should have at least one region per slice: " SIZE_FORMAT,
238 _bitmap_regions_per_slice);
239
240 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
241 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
242 _bitmap_bytes_per_slice, bitmap_page_size);
243
244 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
245 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
246 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
247 _bitmap_region_special = bitmap.special();
248
249 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
250 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
251 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
252 if (!_bitmap_region_special) {
253 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
254 "Cannot commit bitmap memory");
255 }
256
257 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions, _max_workers);
258
259 if (ShenandoahVerify) {
260 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
261 if (!verify_bitmap.special()) {
262 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
263 "Cannot commit verification bitmap memory");
264 }
265 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
266 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
267 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
268 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
269 }
270
271 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
272 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
273 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
274 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
275 _aux_bitmap_region_special = aux_bitmap.special();
276 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
277
278 //
279 // Create regions and region sets
280 //
281 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
282 size_t region_storage_size = align_up(region_align * _num_regions, region_page_size);
283 region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity());
284
285 ReservedSpace region_storage(region_storage_size, region_page_size);
286 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
287 if (!region_storage.special()) {
288 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
289 "Cannot commit region memory");
290 }
291
292 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks.
293 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there.
294 // If not successful, bite a bullet and allocate at whatever address.
295 {
296 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
297 size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align);
298
299 uintptr_t min = round_up_power_of_2(cset_align);
300 uintptr_t max = (1u << 30u);
301
302 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
303 char* req_addr = (char*)addr;
304 assert(is_aligned(req_addr, cset_align), "Should be aligned");
305 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size(), req_addr);
306 if (cset_rs.is_reserved()) {
307 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr);
308 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
309 break;
310 }
311 }
312
313 if (_collection_set == nullptr) {
314 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size());
315 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
316 }
317 }
318
319 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
320 _free_set = new ShenandoahFreeSet(this, _num_regions);
321
322 {
323 ShenandoahHeapLocker locker(lock());
324
325 for (size_t i = 0; i < _num_regions; i++) {
326 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
327 bool is_committed = i < num_committed_regions;
328 void* loc = region_storage.base() + i * region_align;
329
330 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
331 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
332
333 _marking_context->initialize_top_at_mark_start(r);
334 _regions[i] = r;
335 assert(!collection_set()->is_in(i), "New region should not be in collection set");
336 }
337
338 // Initialize to complete
339 _marking_context->mark_complete();
340
341 _free_set->rebuild();
342 }
343
344 if (AlwaysPreTouch) {
345 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
346 // before initialize() below zeroes it with initializing thread. For any given region,
347 // we touch the region and the corresponding bitmaps from the same thread.
348 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
349
350 _pretouch_heap_page_size = heap_page_size;
351 _pretouch_bitmap_page_size = bitmap_page_size;
352
353 #ifdef LINUX
354 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
355 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
356 // them into huge one. Therefore, we need to pretouch with smaller pages.
357 if (UseTransparentHugePages) {
358 _pretouch_heap_page_size = (size_t)os::vm_page_size();
359 _pretouch_bitmap_page_size = (size_t)os::vm_page_size();
360 }
361 #endif
362
363 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
364 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
365
366 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size);
367 _workers->run_task(&bcl);
368
369 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size);
370 _workers->run_task(&hcl);
371 }
372
373 //
374 // Initialize the rest of GC subsystems
375 //
376
377 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
378 for (uint worker = 0; worker < _max_workers; worker++) {
379 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
380 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
381 }
382
383 // There should probably be Shenandoah-specific options for these,
384 // just as there are G1-specific options.
385 {
386 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
387 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
388 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
389 }
390
391 _monitoring_support = new ShenandoahMonitoringSupport(this);
392 _phase_timings = new ShenandoahPhaseTimings(max_workers());
393 ShenandoahCodeRoots::initialize();
394
395 if (ShenandoahPacing) {
396 _pacer = new ShenandoahPacer(this);
397 _pacer->setup_for_idle();
398 } else {
399 _pacer = nullptr;
400 }
401
402 _control_thread = new ShenandoahControlThread();
403
404 ShenandoahInitLogger::print();
405
406 return JNI_OK;
407 }
408
409 void ShenandoahHeap::initialize_mode() {
410 if (ShenandoahGCMode != nullptr) {
411 if (strcmp(ShenandoahGCMode, "satb") == 0) {
412 _gc_mode = new ShenandoahSATBMode();
413 } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
414 _gc_mode = new ShenandoahIUMode();
415 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
416 _gc_mode = new ShenandoahPassiveMode();
417 } else {
418 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
419 }
420 } else {
421 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)");
422 }
423 _gc_mode->initialize_flags();
424 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
425 vm_exit_during_initialization(
426 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
427 _gc_mode->name()));
428 }
429 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
430 vm_exit_during_initialization(
431 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
432 _gc_mode->name()));
433 }
434 }
435
436 void ShenandoahHeap::initialize_heuristics() {
437 assert(_gc_mode != nullptr, "Must be initialized");
438 _heuristics = _gc_mode->initialize_heuristics();
439
440 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
441 vm_exit_during_initialization(
442 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
443 _heuristics->name()));
444 }
445 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
446 vm_exit_during_initialization(
447 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
448 _heuristics->name()));
449 }
450 }
451
452 #ifdef _MSC_VER
453 #pragma warning( push )
454 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
455 #endif
456
457 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
458 CollectedHeap(),
459 _initial_size(0),
460 _used(0),
461 _committed(0),
462 _bytes_allocated_since_gc_start(0),
463 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
464 _workers(nullptr),
465 _safepoint_workers(nullptr),
466 _heap_region_special(false),
467 _num_regions(0),
468 _regions(nullptr),
469 _update_refs_iterator(this),
470 _control_thread(nullptr),
471 _shenandoah_policy(policy),
472 _gc_mode(nullptr),
473 _heuristics(nullptr),
474 _free_set(nullptr),
475 _pacer(nullptr),
476 _verifier(nullptr),
477 _phase_timings(nullptr),
478 _monitoring_support(nullptr),
479 _memory_pool(nullptr),
480 _stw_memory_manager("Shenandoah Pauses"),
481 _cycle_memory_manager("Shenandoah Cycles"),
482 _gc_timer(new ConcurrentGCTimer()),
483 _soft_ref_policy(),
484 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
485 _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))),
486 _marking_context(nullptr),
487 _bitmap_size(0),
488 _bitmap_regions_per_slice(0),
489 _bitmap_bytes_per_slice(0),
490 _bitmap_region_special(false),
491 _aux_bitmap_region_special(false),
492 _liveness_cache(nullptr),
493 _collection_set(nullptr)
494 {
495 // Initialize GC mode early, so we can adjust barrier support
496 initialize_mode();
497 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
498
499 _max_workers = MAX2(_max_workers, 1U);
500 _workers = new ShenandoahWorkerThreads("Shenandoah GC Threads", _max_workers);
501 if (_workers == nullptr) {
502 vm_exit_during_initialization("Failed necessary allocation.");
503 } else {
504 _workers->initialize_workers();
505 }
506
507 if (ParallelGCThreads > 1) {
508 _safepoint_workers = new ShenandoahWorkerThreads("Safepoint Cleanup Thread",
509 ParallelGCThreads);
510 _safepoint_workers->initialize_workers();
511 }
512 }
513
514 #ifdef _MSC_VER
515 #pragma warning( pop )
516 #endif
517
518 class ShenandoahResetBitmapTask : public WorkerTask {
519 private:
520 ShenandoahRegionIterator _regions;
521
522 public:
523 ShenandoahResetBitmapTask() :
524 WorkerTask("Shenandoah Reset Bitmap") {}
525
526 void work(uint worker_id) {
527 ShenandoahHeapRegion* region = _regions.next();
528 ShenandoahHeap* heap = ShenandoahHeap::heap();
529 ShenandoahMarkingContext* const ctx = heap->marking_context();
530 while (region != nullptr) {
531 if (heap->is_bitmap_slice_committed(region)) {
532 ctx->clear_bitmap(region);
533 }
534 region = _regions.next();
535 }
536 }
537 };
538
539 void ShenandoahHeap::reset_mark_bitmap() {
540 assert_gc_workers(_workers->active_workers());
541 mark_incomplete_marking_context();
542
543 ShenandoahResetBitmapTask task;
544 _workers->run_task(&task);
545 }
546
547 void ShenandoahHeap::print_on(outputStream* st) const {
548 st->print_cr("Shenandoah Heap");
549 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
550 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
551 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
552 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
553 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
554 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
555 num_regions(),
556 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
557 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
558
559 st->print("Status: ");
560 if (has_forwarded_objects()) st->print("has forwarded objects, ");
561 if (is_concurrent_mark_in_progress()) st->print("marking, ");
562 if (is_evacuation_in_progress()) st->print("evacuating, ");
563 if (is_update_refs_in_progress()) st->print("updating refs, ");
564 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
565 if (is_full_gc_in_progress()) st->print("full gc, ");
566 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
567 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
568 if (is_concurrent_strong_root_in_progress() &&
569 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
570
571 if (cancelled_gc()) {
572 st->print("cancelled");
573 } else {
574 st->print("not cancelled");
575 }
576 st->cr();
577
578 st->print_cr("Reserved region:");
579 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
580 p2i(reserved_region().start()),
581 p2i(reserved_region().end()));
582
583 ShenandoahCollectionSet* cset = collection_set();
584 st->print_cr("Collection set:");
585 if (cset != nullptr) {
586 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
587 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
588 } else {
589 st->print_cr(" (null)");
590 }
591
592 st->cr();
593 MetaspaceUtils::print_on(st);
594
595 if (Verbose) {
596 st->cr();
597 print_heap_regions_on(st);
598 }
599 }
600
601 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
602 public:
603 void do_thread(Thread* thread) {
604 assert(thread != nullptr, "Sanity");
605 assert(thread->is_Worker_thread(), "Only worker thread expected");
606 ShenandoahThreadLocalData::initialize_gclab(thread);
607 }
608 };
609
610 void ShenandoahHeap::post_initialize() {
611 CollectedHeap::post_initialize();
612 MutexLocker ml(Threads_lock);
613
614 ShenandoahInitWorkerGCLABClosure init_gclabs;
615 _workers->threads_do(&init_gclabs);
616
617 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
618 // Now, we will let WorkerThreads to initialize gclab when new worker is created.
619 _workers->set_initialize_gclab();
620 if (_safepoint_workers != nullptr) {
621 _safepoint_workers->threads_do(&init_gclabs);
622 _safepoint_workers->set_initialize_gclab();
623 }
624
625 _heuristics->initialize();
626
627 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
628 }
629
630 size_t ShenandoahHeap::used() const {
631 return Atomic::load(&_used);
632 }
633
634 size_t ShenandoahHeap::committed() const {
635 return Atomic::load(&_committed);
636 }
637
638 void ShenandoahHeap::increase_committed(size_t bytes) {
639 shenandoah_assert_heaplocked_or_safepoint();
640 _committed += bytes;
641 }
642
643 void ShenandoahHeap::decrease_committed(size_t bytes) {
644 shenandoah_assert_heaplocked_or_safepoint();
645 _committed -= bytes;
646 }
647
648 void ShenandoahHeap::increase_used(size_t bytes) {
649 Atomic::add(&_used, bytes, memory_order_relaxed);
650 }
651
652 void ShenandoahHeap::set_used(size_t bytes) {
653 Atomic::store(&_used, bytes);
654 }
655
656 void ShenandoahHeap::decrease_used(size_t bytes) {
657 assert(used() >= bytes, "never decrease heap size by more than we've left");
658 Atomic::sub(&_used, bytes, memory_order_relaxed);
659 }
660
661 void ShenandoahHeap::increase_allocated(size_t bytes) {
662 Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed);
663 }
664
665 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
666 size_t bytes = words * HeapWordSize;
667 if (!waste) {
668 increase_used(bytes);
669 }
670 increase_allocated(bytes);
671 if (ShenandoahPacing) {
672 control_thread()->pacing_notify_alloc(words);
673 if (waste) {
674 pacer()->claim_for_alloc(words, true);
675 }
676 }
677 }
678
679 size_t ShenandoahHeap::capacity() const {
680 return committed();
681 }
682
683 size_t ShenandoahHeap::max_capacity() const {
684 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
685 }
686
687 size_t ShenandoahHeap::soft_max_capacity() const {
688 size_t v = Atomic::load(&_soft_max_size);
689 assert(min_capacity() <= v && v <= max_capacity(),
690 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
691 min_capacity(), v, max_capacity());
692 return v;
693 }
694
695 void ShenandoahHeap::set_soft_max_capacity(size_t v) {
696 assert(min_capacity() <= v && v <= max_capacity(),
697 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
698 min_capacity(), v, max_capacity());
699 Atomic::store(&_soft_max_size, v);
700 }
701
702 size_t ShenandoahHeap::min_capacity() const {
703 return _minimum_size;
704 }
705
706 size_t ShenandoahHeap::initial_capacity() const {
707 return _initial_size;
708 }
709
710 bool ShenandoahHeap::is_in(const void* p) const {
711 HeapWord* heap_base = (HeapWord*) base();
712 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
713 return p >= heap_base && p < last_region_end;
714 }
715
716 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
717 assert (ShenandoahUncommit, "should be enabled");
718
719 // Application allocates from the beginning of the heap, and GC allocates at
720 // the end of it. It is more efficient to uncommit from the end, so that applications
721 // could enjoy the near committed regions. GC allocations are much less frequent,
722 // and therefore can accept the committing costs.
723
724 size_t count = 0;
725 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
726 ShenandoahHeapRegion* r = get_region(i - 1);
727 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
728 ShenandoahHeapLocker locker(lock());
729 if (r->is_empty_committed()) {
730 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
731 break;
732 }
733
734 r->make_uncommitted();
735 count++;
736 }
737 }
738 SpinPause(); // allow allocators to take the lock
739 }
740
741 if (count > 0) {
742 control_thread()->notify_heap_changed();
743 }
744 }
745
746 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
747 // New object should fit the GCLAB size
748 size_t min_size = MAX2(size, PLAB::min_size());
749
750 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
751 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
752 new_size = MIN2(new_size, PLAB::max_size());
753 new_size = MAX2(new_size, PLAB::min_size());
754
755 // Record new heuristic value even if we take any shortcut. This captures
756 // the case when moderately-sized objects always take a shortcut. At some point,
757 // heuristics should catch up with them.
758 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
759
760 if (new_size < size) {
761 // New size still does not fit the object. Fall back to shared allocation.
762 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
763 return nullptr;
764 }
765
766 // Retire current GCLAB, and allocate a new one.
767 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
768 gclab->retire();
769
770 size_t actual_size = 0;
771 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
772 if (gclab_buf == nullptr) {
773 return nullptr;
774 }
775
776 assert (size <= actual_size, "allocation should fit");
777
778 if (ZeroTLAB) {
779 // ..and clear it.
780 Copy::zero_to_words(gclab_buf, actual_size);
781 } else {
782 // ...and zap just allocated object.
783 #ifdef ASSERT
784 // Skip mangling the space corresponding to the object header to
785 // ensure that the returned space is not considered parsable by
786 // any concurrent GC thread.
787 size_t hdr_size = oopDesc::header_size();
788 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
789 #endif // ASSERT
790 }
791 gclab->set_buf(gclab_buf, actual_size);
792 return gclab->allocate(size);
793 }
794
795 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
796 size_t requested_size,
797 size_t* actual_size) {
798 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
799 HeapWord* res = allocate_memory(req);
800 if (res != nullptr) {
801 *actual_size = req.actual_size();
802 } else {
803 *actual_size = 0;
804 }
805 return res;
806 }
807
808 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
809 size_t word_size,
810 size_t* actual_size) {
811 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
812 HeapWord* res = allocate_memory(req);
813 if (res != nullptr) {
814 *actual_size = req.actual_size();
815 } else {
816 *actual_size = 0;
817 }
818 return res;
819 }
820
821 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
822 intptr_t pacer_epoch = 0;
823 bool in_new_region = false;
824 HeapWord* result = nullptr;
825
826 if (req.is_mutator_alloc()) {
827 if (ShenandoahPacing) {
828 pacer()->pace_for_alloc(req.size());
829 pacer_epoch = pacer()->epoch();
830 }
831
832 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
833 result = allocate_memory_under_lock(req, in_new_region);
834 }
835
836 // Allocation failed, block until control thread reacted, then retry allocation.
837 //
838 // It might happen that one of the threads requesting allocation would unblock
839 // way later after GC happened, only to fail the second allocation, because
840 // other threads have already depleted the free storage. In this case, a better
841 // strategy is to try again, as long as GC makes progress (or until at least
842 // one full GC has completed).
843 size_t original_count = shenandoah_policy()->full_gc_count();
844 while (result == nullptr
845 && (_progress_last_gc.is_set() || original_count == shenandoah_policy()->full_gc_count())) {
846 control_thread()->handle_alloc_failure(req);
847 result = allocate_memory_under_lock(req, in_new_region);
848 }
849 } else {
850 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
851 result = allocate_memory_under_lock(req, in_new_region);
852 // Do not call handle_alloc_failure() here, because we cannot block.
853 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
854 }
855
856 if (in_new_region) {
857 control_thread()->notify_heap_changed();
858 }
859
860 if (result != nullptr) {
861 size_t requested = req.size();
862 size_t actual = req.actual_size();
863
864 assert (req.is_lab_alloc() || (requested == actual),
865 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
866 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
867
868 if (req.is_mutator_alloc()) {
869 notify_mutator_alloc_words(actual, false);
870
871 // If we requested more than we were granted, give the rest back to pacer.
872 // This only matters if we are in the same pacing epoch: do not try to unpace
873 // over the budget for the other phase.
874 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
875 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
876 }
877 } else {
878 increase_used(actual*HeapWordSize);
879 }
880 }
881
882 return result;
883 }
884
885 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
886 ShenandoahHeapLocker locker(lock());
887 return _free_set->allocate(req, in_new_region);
888 }
889
890 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
891 bool* gc_overhead_limit_was_exceeded) {
892 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
893 return allocate_memory(req);
894 }
895
896 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
897 size_t size,
898 Metaspace::MetadataType mdtype) {
899 MetaWord* result;
900
901 // Inform metaspace OOM to GC heuristics if class unloading is possible.
902 if (heuristics()->can_unload_classes()) {
903 ShenandoahHeuristics* h = heuristics();
904 h->record_metaspace_oom();
905 }
906
907 // Expand and retry allocation
908 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
909 if (result != nullptr) {
910 return result;
911 }
912
913 // Start full GC
914 collect(GCCause::_metadata_GC_clear_soft_refs);
915
916 // Retry allocation
917 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
918 if (result != nullptr) {
919 return result;
920 }
921
922 // Expand and retry allocation
923 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
924 if (result != nullptr) {
925 return result;
926 }
927
928 // Out of memory
929 return nullptr;
930 }
931
932 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
933 private:
934 ShenandoahHeap* const _heap;
935 Thread* const _thread;
936 public:
937 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
938 _heap(heap), _thread(Thread::current()) {}
939
940 void do_object(oop p) {
941 shenandoah_assert_marked(nullptr, p);
942 if (!p->is_forwarded()) {
943 _heap->evacuate_object(p, _thread);
944 }
945 }
946 };
947
948 class ShenandoahEvacuationTask : public WorkerTask {
949 private:
950 ShenandoahHeap* const _sh;
951 ShenandoahCollectionSet* const _cs;
952 bool _concurrent;
953 public:
954 ShenandoahEvacuationTask(ShenandoahHeap* sh,
955 ShenandoahCollectionSet* cs,
956 bool concurrent) :
957 WorkerTask("Shenandoah Evacuation"),
958 _sh(sh),
959 _cs(cs),
960 _concurrent(concurrent)
961 {}
962
963 void work(uint worker_id) {
964 if (_concurrent) {
965 ShenandoahConcurrentWorkerSession worker_session(worker_id);
966 ShenandoahSuspendibleThreadSetJoiner stsj;
967 ShenandoahEvacOOMScope oom_evac_scope;
968 do_work();
969 } else {
970 ShenandoahParallelWorkerSession worker_session(worker_id);
971 ShenandoahEvacOOMScope oom_evac_scope;
972 do_work();
973 }
974 }
975
976 private:
977 void do_work() {
978 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
979 ShenandoahHeapRegion* r;
980 while ((r =_cs->claim_next()) != nullptr) {
981 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
982 _sh->marked_object_iterate(r, &cl);
983
984 if (ShenandoahPacing) {
985 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
986 }
987
988 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
989 break;
990 }
991 }
992 }
993 };
994
995 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
996 ShenandoahEvacuationTask task(this, _collection_set, concurrent);
997 workers()->run_task(&task);
998 }
999
1000 void ShenandoahHeap::trash_cset_regions() {
1001 ShenandoahHeapLocker locker(lock());
1002
1003 ShenandoahCollectionSet* set = collection_set();
1004 ShenandoahHeapRegion* r;
1005 set->clear_current_index();
1006 while ((r = set->next()) != nullptr) {
1007 r->make_trash();
1008 }
1009 collection_set()->clear();
1010 }
1011
1012 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1013 st->print_cr("Heap Regions:");
1014 st->print_cr("Region state: EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HP=pinned humongous start");
1015 st->print_cr(" HC=humongous continuation, CS=collection set, TR=trash, P=pinned, CSP=pinned collection set");
1016 st->print_cr("BTE=bottom/top/end, TAMS=top-at-mark-start");
1017 st->print_cr("UWM=update watermark, U=used");
1018 st->print_cr("T=TLAB allocs, G=GCLAB allocs");
1019 st->print_cr("S=shared allocs, L=live data");
1020 st->print_cr("CP=critical pins");
1021
1022 for (size_t i = 0; i < num_regions(); i++) {
1023 get_region(i)->print_on(st);
1024 }
1025 }
1026
1027 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1028 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1029
1030 oop humongous_obj = cast_to_oop(start->bottom());
1031 size_t size = humongous_obj->size();
1032 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1033 size_t index = start->index() + required_regions - 1;
1034
1035 assert(!start->has_live(), "liveness must be zero");
1036
1037 for(size_t i = 0; i < required_regions; i++) {
1038 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1039 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1040 ShenandoahHeapRegion* region = get_region(index --);
1041
1042 assert(region->is_humongous(), "expect correct humongous start or continuation");
1043 assert(!region->is_cset(), "Humongous region should not be in collection set");
1044
1045 region->make_trash_immediate();
1046 }
1047 }
1048
1049 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1050 public:
1051 ShenandoahCheckCleanGCLABClosure() {}
1052 void do_thread(Thread* thread) {
1053 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1054 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1055 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1056 }
1057 };
1058
1059 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1060 private:
1061 bool const _resize;
1062 public:
1063 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1064 void do_thread(Thread* thread) {
1065 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1066 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1067 gclab->retire();
1068 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1069 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1070 }
1071 }
1072 };
1073
1074 void ShenandoahHeap::labs_make_parsable() {
1075 assert(UseTLAB, "Only call with UseTLAB");
1076
1077 ShenandoahRetireGCLABClosure cl(false);
1078
1079 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1080 ThreadLocalAllocBuffer& tlab = t->tlab();
1081 tlab.make_parsable();
1082 cl.do_thread(t);
1083 }
1084
1085 workers()->threads_do(&cl);
1086 }
1087
1088 void ShenandoahHeap::tlabs_retire(bool resize) {
1089 assert(UseTLAB, "Only call with UseTLAB");
1090 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1091
1092 ThreadLocalAllocStats stats;
1093
1094 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1095 ThreadLocalAllocBuffer& tlab = t->tlab();
1096 tlab.retire(&stats);
1097 if (resize) {
1098 tlab.resize();
1099 }
1100 }
1101
1102 stats.publish();
1103
1104 #ifdef ASSERT
1105 ShenandoahCheckCleanGCLABClosure cl;
1106 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1107 cl.do_thread(t);
1108 }
1109 workers()->threads_do(&cl);
1110 #endif
1111 }
1112
1113 void ShenandoahHeap::gclabs_retire(bool resize) {
1114 assert(UseTLAB, "Only call with UseTLAB");
1115 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1116
1117 ShenandoahRetireGCLABClosure cl(resize);
1118 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1119 cl.do_thread(t);
1120 }
1121 workers()->threads_do(&cl);
1122
1123 if (safepoint_workers() != nullptr) {
1124 safepoint_workers()->threads_do(&cl);
1125 }
1126 }
1127
1128 // Returns size in bytes
1129 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1130 // Return the max allowed size, and let the allocation path
1131 // figure out the safe size for current allocation.
1132 return ShenandoahHeapRegion::max_tlab_size_bytes();
1133 }
1134
1135 size_t ShenandoahHeap::max_tlab_size() const {
1136 // Returns size in words
1137 return ShenandoahHeapRegion::max_tlab_size_words();
1138 }
1139
1140 void ShenandoahHeap::collect(GCCause::Cause cause) {
1141 control_thread()->request_gc(cause);
1142 }
1143
1144 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1145 //assert(false, "Shouldn't need to do full collections");
1146 }
1147
1148 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1149 ShenandoahHeapRegion* r = heap_region_containing(addr);
1150 if (r != nullptr) {
1151 return r->block_start(addr);
1152 }
1153 return nullptr;
1154 }
1155
1156 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1157 ShenandoahHeapRegion* r = heap_region_containing(addr);
1158 return r->block_is_obj(addr);
1159 }
1160
1161 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1162 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1163 }
1164
1165 void ShenandoahHeap::prepare_for_verify() {
1166 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1167 labs_make_parsable();
1168 }
1169 }
1170
1171 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1172 tcl->do_thread(_control_thread);
1173 workers()->threads_do(tcl);
1174 if (_safepoint_workers != nullptr) {
1175 _safepoint_workers->threads_do(tcl);
1176 }
1177 }
1178
1179 void ShenandoahHeap::print_tracing_info() const {
1180 LogTarget(Info, gc, stats) lt;
1181 if (lt.is_enabled()) {
1182 ResourceMark rm;
1183 LogStream ls(lt);
1184
1185 phase_timings()->print_global_on(&ls);
1186
1187 ls.cr();
1188 ls.cr();
1189
1190 shenandoah_policy()->print_gc_stats(&ls);
1191
1192 ls.cr();
1193 ls.cr();
1194 }
1195 }
1196
1197 void ShenandoahHeap::verify(VerifyOption vo) {
1198 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1199 if (ShenandoahVerify) {
1200 verifier()->verify_generic(vo);
1201 } else {
1202 // TODO: Consider allocating verification bitmaps on demand,
1203 // and turn this on unconditionally.
1204 }
1205 }
1206 }
1207 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1208 return _free_set->capacity();
1209 }
1210
1211 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1212 private:
1213 MarkBitMap* _bitmap;
1214 ShenandoahScanObjectStack* _oop_stack;
1215 ShenandoahHeap* const _heap;
1216 ShenandoahMarkingContext* const _marking_context;
1217
1218 template <class T>
1219 void do_oop_work(T* p) {
1220 T o = RawAccess<>::oop_load(p);
1221 if (!CompressedOops::is_null(o)) {
1222 oop obj = CompressedOops::decode_not_null(o);
1223 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1224 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1225 return;
1226 }
1227 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1228
1229 assert(oopDesc::is_oop(obj), "must be a valid oop");
1230 if (!_bitmap->is_marked(obj)) {
1231 _bitmap->mark(obj);
1232 _oop_stack->push(obj);
1233 }
1234 }
1235 }
1236 public:
1237 ObjectIterateScanRootClosure(MarkBitMap* bitmap, ShenandoahScanObjectStack* oop_stack) :
1238 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1239 _marking_context(_heap->marking_context()) {}
1240 void do_oop(oop* p) { do_oop_work(p); }
1241 void do_oop(narrowOop* p) { do_oop_work(p); }
1242 };
1243
1244 /*
1245 * This is public API, used in preparation of object_iterate().
1246 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1247 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1248 * control, we call SH::tlabs_retire, SH::gclabs_retire.
1249 */
1250 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1251 // No-op.
1252 }
1253
1254 /*
1255 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1256 *
1257 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1258 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1259 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1260 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1261 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1262 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1263 * wiped the bitmap in preparation for next marking).
1264 *
1265 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1266 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1267 * is allowed to report dead objects, but is not required to do so.
1268 */
1269 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1270 // Reset bitmap
1271 if (!prepare_aux_bitmap_for_iteration())
1272 return;
1273
1274 ShenandoahScanObjectStack oop_stack;
1275 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1276 // Seed the stack with root scan
1277 scan_roots_for_iteration(&oop_stack, &oops);
1278
1279 // Work through the oop stack to traverse heap
1280 while (! oop_stack.is_empty()) {
1281 oop obj = oop_stack.pop();
1282 assert(oopDesc::is_oop(obj), "must be a valid oop");
1283 cl->do_object(obj);
1284 obj->oop_iterate(&oops);
1285 }
1286
1287 assert(oop_stack.is_empty(), "should be empty");
1288 // Reclaim bitmap
1289 reclaim_aux_bitmap_for_iteration();
1290 }
1291
1292 bool ShenandoahHeap::prepare_aux_bitmap_for_iteration() {
1293 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1294
1295 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1296 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1297 return false;
1298 }
1299 // Reset bitmap
1300 _aux_bit_map.clear();
1301 return true;
1302 }
1303
1304 void ShenandoahHeap::scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops) {
1305 // Process GC roots according to current GC cycle
1306 // This populates the work stack with initial objects
1307 // It is important to relinquish the associated locks before diving
1308 // into heap dumper
1309 uint n_workers = safepoint_workers() != nullptr ? safepoint_workers()->active_workers() : 1;
1310 ShenandoahHeapIterationRootScanner rp(n_workers);
1311 rp.roots_do(oops);
1312 }
1313
1314 void ShenandoahHeap::reclaim_aux_bitmap_for_iteration() {
1315 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1316 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1317 }
1318 }
1319
1320 // Closure for parallelly iterate objects
1321 class ShenandoahObjectIterateParScanClosure : public BasicOopIterateClosure {
1322 private:
1323 MarkBitMap* _bitmap;
1324 ShenandoahObjToScanQueue* _queue;
1325 ShenandoahHeap* const _heap;
1326 ShenandoahMarkingContext* const _marking_context;
1327
1328 template <class T>
1329 void do_oop_work(T* p) {
1330 T o = RawAccess<>::oop_load(p);
1331 if (!CompressedOops::is_null(o)) {
1332 oop obj = CompressedOops::decode_not_null(o);
1333 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1334 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1335 return;
1336 }
1337 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1338
1339 assert(oopDesc::is_oop(obj), "Must be a valid oop");
1340 if (_bitmap->par_mark(obj)) {
1341 _queue->push(ShenandoahMarkTask(obj));
1342 }
1343 }
1344 }
1345 public:
1346 ShenandoahObjectIterateParScanClosure(MarkBitMap* bitmap, ShenandoahObjToScanQueue* q) :
1347 _bitmap(bitmap), _queue(q), _heap(ShenandoahHeap::heap()),
1348 _marking_context(_heap->marking_context()) {}
1349 void do_oop(oop* p) { do_oop_work(p); }
1350 void do_oop(narrowOop* p) { do_oop_work(p); }
1351 };
1352
1353 // Object iterator for parallel heap iteraion.
1354 // The root scanning phase happenes in construction as a preparation of
1355 // parallel marking queues.
1356 // Every worker processes it's own marking queue. work-stealing is used
1357 // to balance workload.
1358 class ShenandoahParallelObjectIterator : public ParallelObjectIteratorImpl {
1359 private:
1360 uint _num_workers;
1361 bool _init_ready;
1362 MarkBitMap* _aux_bit_map;
1363 ShenandoahHeap* _heap;
1364 ShenandoahScanObjectStack _roots_stack; // global roots stack
1365 ShenandoahObjToScanQueueSet* _task_queues;
1366 public:
1367 ShenandoahParallelObjectIterator(uint num_workers, MarkBitMap* bitmap) :
1368 _num_workers(num_workers),
1369 _init_ready(false),
1370 _aux_bit_map(bitmap),
1371 _heap(ShenandoahHeap::heap()) {
1372 // Initialize bitmap
1373 _init_ready = _heap->prepare_aux_bitmap_for_iteration();
1374 if (!_init_ready) {
1375 return;
1376 }
1377
1378 ObjectIterateScanRootClosure oops(_aux_bit_map, &_roots_stack);
1379 _heap->scan_roots_for_iteration(&_roots_stack, &oops);
1380
1381 _init_ready = prepare_worker_queues();
1382 }
1383
1384 ~ShenandoahParallelObjectIterator() {
1385 // Reclaim bitmap
1386 _heap->reclaim_aux_bitmap_for_iteration();
1387 // Reclaim queue for workers
1388 if (_task_queues!= nullptr) {
1389 for (uint i = 0; i < _num_workers; ++i) {
1390 ShenandoahObjToScanQueue* q = _task_queues->queue(i);
1391 if (q != nullptr) {
1392 delete q;
1393 _task_queues->register_queue(i, nullptr);
1394 }
1395 }
1396 delete _task_queues;
1397 _task_queues = nullptr;
1398 }
1399 }
1400
1401 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
1402 if (_init_ready) {
1403 object_iterate_parallel(cl, worker_id, _task_queues);
1404 }
1405 }
1406
1407 private:
1408 // Divide global root_stack into worker queues
1409 bool prepare_worker_queues() {
1410 _task_queues = new ShenandoahObjToScanQueueSet((int) _num_workers);
1411 // Initialize queues for every workers
1412 for (uint i = 0; i < _num_workers; ++i) {
1413 ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue();
1414 _task_queues->register_queue(i, task_queue);
1415 }
1416 // Divide roots among the workers. Assume that object referencing distribution
1417 // is related with root kind, use round-robin to make every worker have same chance
1418 // to process every kind of roots
1419 size_t roots_num = _roots_stack.size();
1420 if (roots_num == 0) {
1421 // No work to do
1422 return false;
1423 }
1424
1425 for (uint j = 0; j < roots_num; j++) {
1426 uint stack_id = j % _num_workers;
1427 oop obj = _roots_stack.pop();
1428 _task_queues->queue(stack_id)->push(ShenandoahMarkTask(obj));
1429 }
1430 return true;
1431 }
1432
1433 void object_iterate_parallel(ObjectClosure* cl,
1434 uint worker_id,
1435 ShenandoahObjToScanQueueSet* queue_set) {
1436 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1437 assert(queue_set != nullptr, "task queue must not be null");
1438
1439 ShenandoahObjToScanQueue* q = queue_set->queue(worker_id);
1440 assert(q != nullptr, "object iterate queue must not be null");
1441
1442 ShenandoahMarkTask t;
1443 ShenandoahObjectIterateParScanClosure oops(_aux_bit_map, q);
1444
1445 // Work through the queue to traverse heap.
1446 // Steal when there is no task in queue.
1447 while (q->pop(t) || queue_set->steal(worker_id, t)) {
1448 oop obj = t.obj();
1449 assert(oopDesc::is_oop(obj), "must be a valid oop");
1450 cl->do_object(obj);
1451 obj->oop_iterate(&oops);
1452 }
1453 assert(q->is_empty(), "should be empty");
1454 }
1455 };
1456
1457 ParallelObjectIteratorImpl* ShenandoahHeap::parallel_object_iterator(uint workers) {
1458 return new ShenandoahParallelObjectIterator(workers, &_aux_bit_map);
1459 }
1460
1461 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1462 void ShenandoahHeap::keep_alive(oop obj) {
1463 if (is_concurrent_mark_in_progress() && (obj != nullptr)) {
1464 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1465 }
1466 }
1467
1468 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1469 for (size_t i = 0; i < num_regions(); i++) {
1470 ShenandoahHeapRegion* current = get_region(i);
1471 blk->heap_region_do(current);
1472 }
1473 }
1474
1475 class ShenandoahParallelHeapRegionTask : public WorkerTask {
1476 private:
1477 ShenandoahHeap* const _heap;
1478 ShenandoahHeapRegionClosure* const _blk;
1479
1480 shenandoah_padding(0);
1481 volatile size_t _index;
1482 shenandoah_padding(1);
1483
1484 public:
1485 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1486 WorkerTask("Shenandoah Parallel Region Operation"),
1487 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1488
1489 void work(uint worker_id) {
1490 ShenandoahParallelWorkerSession worker_session(worker_id);
1491 size_t stride = ShenandoahParallelRegionStride;
1492
1493 size_t max = _heap->num_regions();
1494 while (Atomic::load(&_index) < max) {
1495 size_t cur = Atomic::fetch_then_add(&_index, stride, memory_order_relaxed);
1496 size_t start = cur;
1497 size_t end = MIN2(cur + stride, max);
1498 if (start >= max) break;
1499
1500 for (size_t i = cur; i < end; i++) {
1501 ShenandoahHeapRegion* current = _heap->get_region(i);
1502 _blk->heap_region_do(current);
1503 }
1504 }
1505 }
1506 };
1507
1508 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1509 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1510 if (num_regions() > ShenandoahParallelRegionStride) {
1511 ShenandoahParallelHeapRegionTask task(blk);
1512 workers()->run_task(&task);
1513 } else {
1514 heap_region_iterate(blk);
1515 }
1516 }
1517
1518 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1519 private:
1520 ShenandoahMarkingContext* const _ctx;
1521 public:
1522 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1523
1524 void heap_region_do(ShenandoahHeapRegion* r) {
1525 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1526 if (r->is_active()) {
1527 // Check if region needs updating its TAMS. We have updated it already during concurrent
1528 // reset, so it is very likely we don't need to do another write here.
1529 if (_ctx->top_at_mark_start(r) != r->top()) {
1530 _ctx->capture_top_at_mark_start(r);
1531 }
1532 } else {
1533 assert(_ctx->top_at_mark_start(r) == r->top(),
1534 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1535 }
1536 }
1537
1538 bool is_thread_safe() { return true; }
1539 };
1540
1541 class ShenandoahRendezvousClosure : public HandshakeClosure {
1542 public:
1543 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
1544 inline void do_thread(Thread* thread) {}
1545 };
1546
1547 void ShenandoahHeap::rendezvous_threads() {
1548 ShenandoahRendezvousClosure cl;
1549 Handshake::execute(&cl);
1550 }
1551
1552 void ShenandoahHeap::recycle_trash() {
1553 free_set()->recycle_trash();
1554 }
1555
1556 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1557 private:
1558 ShenandoahMarkingContext* const _ctx;
1559 public:
1560 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1561
1562 void heap_region_do(ShenandoahHeapRegion* r) {
1563 if (r->is_active()) {
1564 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1565 // anyway to capture any updates that happened since now.
1566 r->clear_live_data();
1567 _ctx->capture_top_at_mark_start(r);
1568 }
1569 }
1570
1571 bool is_thread_safe() { return true; }
1572 };
1573
1574 void ShenandoahHeap::prepare_gc() {
1575 reset_mark_bitmap();
1576
1577 ShenandoahResetUpdateRegionStateClosure cl;
1578 parallel_heap_region_iterate(&cl);
1579 }
1580
1581 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1582 private:
1583 ShenandoahMarkingContext* const _ctx;
1584 ShenandoahHeapLock* const _lock;
1585
1586 public:
1587 ShenandoahFinalMarkUpdateRegionStateClosure() :
1588 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1589
1590 void heap_region_do(ShenandoahHeapRegion* r) {
1591 if (r->is_active()) {
1592 // All allocations past TAMS are implicitly live, adjust the region data.
1593 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1594 HeapWord *tams = _ctx->top_at_mark_start(r);
1595 HeapWord *top = r->top();
1596 if (top > tams) {
1597 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1598 }
1599
1600 // We are about to select the collection set, make sure it knows about
1601 // current pinning status. Also, this allows trashing more regions that
1602 // now have their pinning status dropped.
1603 if (r->is_pinned()) {
1604 if (r->pin_count() == 0) {
1605 ShenandoahHeapLocker locker(_lock);
1606 r->make_unpinned();
1607 }
1608 } else {
1609 if (r->pin_count() > 0) {
1610 ShenandoahHeapLocker locker(_lock);
1611 r->make_pinned();
1612 }
1613 }
1614
1615 // Remember limit for updating refs. It's guaranteed that we get no
1616 // from-space-refs written from here on.
1617 r->set_update_watermark_at_safepoint(r->top());
1618 } else {
1619 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1620 assert(_ctx->top_at_mark_start(r) == r->top(),
1621 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1622 }
1623 }
1624
1625 bool is_thread_safe() { return true; }
1626 };
1627
1628 void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) {
1629 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
1630 {
1631 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states :
1632 ShenandoahPhaseTimings::degen_gc_final_update_region_states);
1633 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1634 parallel_heap_region_iterate(&cl);
1635
1636 assert_pinned_region_status();
1637 }
1638
1639 {
1640 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset :
1641 ShenandoahPhaseTimings::degen_gc_choose_cset);
1642 ShenandoahHeapLocker locker(lock());
1643 _collection_set->clear();
1644 heuristics()->choose_collection_set(_collection_set);
1645 }
1646
1647 {
1648 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset :
1649 ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset);
1650 ShenandoahHeapLocker locker(lock());
1651 _free_set->rebuild();
1652 }
1653 }
1654
1655 void ShenandoahHeap::do_class_unloading() {
1656 _unloader.unload();
1657 }
1658
1659 void ShenandoahHeap::stw_weak_refs(bool full_gc) {
1660 // Weak refs processing
1661 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
1662 : ShenandoahPhaseTimings::degen_gc_weakrefs;
1663 ShenandoahTimingsTracker t(phase);
1664 ShenandoahGCWorkerPhase worker_phase(phase);
1665 ref_processor()->process_references(phase, workers(), false /* concurrent */);
1666 }
1667
1668 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
1669 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1670
1671 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
1672 // make them parsable for update code to work correctly. Plus, we can compute new sizes
1673 // for future GCLABs here.
1674 if (UseTLAB) {
1675 ShenandoahGCPhase phase(concurrent ?
1676 ShenandoahPhaseTimings::init_update_refs_manage_gclabs :
1677 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs);
1678 gclabs_retire(ResizeTLAB);
1679 }
1680
1681 _update_refs_iterator.reset();
1682 }
1683
1684 void ShenandoahHeap::set_gc_state_all_threads(char state) {
1685 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1686 ShenandoahThreadLocalData::set_gc_state(t, state);
1687 }
1688 }
1689
1690 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1691 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1692 _gc_state.set_cond(mask, value);
1693 set_gc_state_all_threads(_gc_state.raw_value());
1694 }
1695
1696 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1697 assert(!has_forwarded_objects(), "Not expected before/after mark phase");
1698 set_gc_state_mask(MARKING, in_progress);
1699 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1700 }
1701
1702 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1703 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1704 set_gc_state_mask(EVACUATION, in_progress);
1705 }
1706
1707 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
1708 if (in_progress) {
1709 _concurrent_strong_root_in_progress.set();
1710 } else {
1711 _concurrent_strong_root_in_progress.unset();
1712 }
1713 }
1714
1715 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) {
1716 set_gc_state_mask(WEAK_ROOTS, cond);
1717 }
1718
1719 GCTracer* ShenandoahHeap::tracer() {
1720 return shenandoah_policy()->tracer();
1721 }
1722
1723 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1724 return _free_set->used();
1725 }
1726
1727 bool ShenandoahHeap::try_cancel_gc() {
1728 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1729 return prev == CANCELLABLE;
1730 }
1731
1732 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1733 if (try_cancel_gc()) {
1734 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1735 log_info(gc)("%s", msg.buffer());
1736 Events::log(Thread::current(), "%s", msg.buffer());
1737 }
1738 }
1739
1740 uint ShenandoahHeap::max_workers() {
1741 return _max_workers;
1742 }
1743
1744 void ShenandoahHeap::stop() {
1745 // The shutdown sequence should be able to terminate when GC is running.
1746
1747 // Step 0. Notify policy to disable event recording.
1748 _shenandoah_policy->record_shutdown();
1749
1750 // Step 1. Notify control thread that we are in shutdown.
1751 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1752 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1753 control_thread()->prepare_for_graceful_shutdown();
1754
1755 // Step 2. Notify GC workers that we are cancelling GC.
1756 cancel_gc(GCCause::_shenandoah_stop_vm);
1757
1758 // Step 3. Wait until GC worker exits normally.
1759 control_thread()->stop();
1760 }
1761
1762 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
1763 if (!unload_classes()) return;
1764 // Unload classes and purge SystemDictionary.
1765 {
1766 ShenandoahPhaseTimings::Phase phase = full_gc ?
1767 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1768 ShenandoahPhaseTimings::degen_gc_purge_class_unload;
1769 ShenandoahIsAliveSelector is_alive;
1770 CodeCache::UnloadingScope scope(is_alive.is_alive_closure());
1771 ShenandoahGCPhase gc_phase(phase);
1772 ShenandoahGCWorkerPhase worker_phase(phase);
1773 bool purged_class = SystemDictionary::do_unloading(gc_timer());
1774
1775 uint num_workers = _workers->active_workers();
1776 ShenandoahClassUnloadingTask unlink_task(phase, num_workers, purged_class);
1777 _workers->run_task(&unlink_task);
1778 }
1779
1780 {
1781 ShenandoahGCPhase phase(full_gc ?
1782 ShenandoahPhaseTimings::full_gc_purge_cldg :
1783 ShenandoahPhaseTimings::degen_gc_purge_cldg);
1784 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
1785 }
1786 // Resize and verify metaspace
1787 MetaspaceGC::compute_new_size();
1788 DEBUG_ONLY(MetaspaceUtils::verify();)
1789 }
1790
1791 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
1792 // so they should not have forwarded oops.
1793 // However, we do need to "null" dead oops in the roots, if can not be done
1794 // in concurrent cycles.
1795 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
1796 uint num_workers = _workers->active_workers();
1797 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
1798 ShenandoahPhaseTimings::full_gc_purge_weak_par :
1799 ShenandoahPhaseTimings::degen_gc_purge_weak_par;
1800 ShenandoahGCPhase phase(timing_phase);
1801 ShenandoahGCWorkerPhase worker_phase(timing_phase);
1802 // Cleanup weak roots
1803 if (has_forwarded_objects()) {
1804 ShenandoahForwardedIsAliveClosure is_alive;
1805 ShenandoahUpdateRefsClosure keep_alive;
1806 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
1807 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers);
1808 _workers->run_task(&cleaning_task);
1809 } else {
1810 ShenandoahIsAliveClosure is_alive;
1811 #ifdef ASSERT
1812 ShenandoahAssertNotForwardedClosure verify_cl;
1813 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
1814 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers);
1815 #else
1816 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
1817 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers);
1818 #endif
1819 _workers->run_task(&cleaning_task);
1820 }
1821 }
1822
1823 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
1824 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1825 assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC");
1826 ShenandoahGCPhase phase(full_gc ?
1827 ShenandoahPhaseTimings::full_gc_purge :
1828 ShenandoahPhaseTimings::degen_gc_purge);
1829 stw_weak_refs(full_gc);
1830 stw_process_weak_roots(full_gc);
1831 stw_unload_classes(full_gc);
1832 }
1833
1834 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
1835 set_gc_state_mask(HAS_FORWARDED, cond);
1836 }
1837
1838 void ShenandoahHeap::set_unload_classes(bool uc) {
1839 _unload_classes.set_cond(uc);
1840 }
1841
1842 bool ShenandoahHeap::unload_classes() const {
1843 return _unload_classes.is_set();
1844 }
1845
1846 address ShenandoahHeap::in_cset_fast_test_addr() {
1847 ShenandoahHeap* heap = ShenandoahHeap::heap();
1848 assert(heap->collection_set() != nullptr, "Sanity");
1849 return (address) heap->collection_set()->biased_map_address();
1850 }
1851
1852 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
1853 return Atomic::load(&_bytes_allocated_since_gc_start);
1854 }
1855
1856 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
1857 Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0);
1858 }
1859
1860 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
1861 _degenerated_gc_in_progress.set_cond(in_progress);
1862 }
1863
1864 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
1865 _full_gc_in_progress.set_cond(in_progress);
1866 }
1867
1868 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
1869 assert (is_full_gc_in_progress(), "should be");
1870 _full_gc_move_in_progress.set_cond(in_progress);
1871 }
1872
1873 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
1874 set_gc_state_mask(UPDATEREFS, in_progress);
1875 }
1876
1877 void ShenandoahHeap::register_nmethod(nmethod* nm) {
1878 ShenandoahCodeRoots::register_nmethod(nm);
1879 }
1880
1881 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
1882 ShenandoahCodeRoots::unregister_nmethod(nm);
1883 }
1884
1885 void ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
1886 heap_region_containing(o)->record_pin();
1887 }
1888
1889 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
1890 ShenandoahHeapRegion* r = heap_region_containing(o);
1891 assert(r != nullptr, "Sanity");
1892 assert(r->pin_count() > 0, "Region " SIZE_FORMAT " should have non-zero pins", r->index());
1893 r->record_unpin();
1894 }
1895
1896 void ShenandoahHeap::sync_pinned_region_status() {
1897 ShenandoahHeapLocker locker(lock());
1898
1899 for (size_t i = 0; i < num_regions(); i++) {
1900 ShenandoahHeapRegion *r = get_region(i);
1901 if (r->is_active()) {
1902 if (r->is_pinned()) {
1903 if (r->pin_count() == 0) {
1904 r->make_unpinned();
1905 }
1906 } else {
1907 if (r->pin_count() > 0) {
1908 r->make_pinned();
1909 }
1910 }
1911 }
1912 }
1913
1914 assert_pinned_region_status();
1915 }
1916
1917 #ifdef ASSERT
1918 void ShenandoahHeap::assert_pinned_region_status() {
1919 for (size_t i = 0; i < num_regions(); i++) {
1920 ShenandoahHeapRegion* r = get_region(i);
1921 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
1922 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
1923 }
1924 }
1925 #endif
1926
1927 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
1928 return _gc_timer;
1929 }
1930
1931 void ShenandoahHeap::prepare_concurrent_roots() {
1932 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1933 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1934 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
1935 set_concurrent_weak_root_in_progress(true);
1936 if (unload_classes()) {
1937 _unloader.prepare();
1938 }
1939 }
1940
1941 void ShenandoahHeap::finish_concurrent_roots() {
1942 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1943 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1944 if (unload_classes()) {
1945 _unloader.finish();
1946 }
1947 }
1948
1949 #ifdef ASSERT
1950 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
1951 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
1952
1953 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1954 if (UseDynamicNumberOfGCThreads) {
1955 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
1956 } else {
1957 // Use ParallelGCThreads inside safepoints
1958 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
1959 }
1960 } else {
1961 if (UseDynamicNumberOfGCThreads) {
1962 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
1963 } else {
1964 // Use ConcGCThreads outside safepoints
1965 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
1966 }
1967 }
1968 }
1969 #endif
1970
1971 ShenandoahVerifier* ShenandoahHeap::verifier() {
1972 guarantee(ShenandoahVerify, "Should be enabled");
1973 assert (_verifier != nullptr, "sanity");
1974 return _verifier;
1975 }
1976
1977 template<bool CONCURRENT>
1978 class ShenandoahUpdateHeapRefsTask : public WorkerTask {
1979 private:
1980 ShenandoahHeap* _heap;
1981 ShenandoahRegionIterator* _regions;
1982 public:
1983 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
1984 WorkerTask("Shenandoah Update References"),
1985 _heap(ShenandoahHeap::heap()),
1986 _regions(regions) {
1987 }
1988
1989 void work(uint worker_id) {
1990 if (CONCURRENT) {
1991 ShenandoahConcurrentWorkerSession worker_session(worker_id);
1992 ShenandoahSuspendibleThreadSetJoiner stsj;
1993 do_work<ShenandoahConcUpdateRefsClosure>();
1994 } else {
1995 ShenandoahParallelWorkerSession worker_session(worker_id);
1996 do_work<ShenandoahSTWUpdateRefsClosure>();
1997 }
1998 }
1999
2000 private:
2001 template<class T>
2002 void do_work() {
2003 T cl;
2004 ShenandoahHeapRegion* r = _regions->next();
2005 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2006 while (r != nullptr) {
2007 HeapWord* update_watermark = r->get_update_watermark();
2008 assert (update_watermark >= r->bottom(), "sanity");
2009 if (r->is_active() && !r->is_cset()) {
2010 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2011 }
2012 if (ShenandoahPacing) {
2013 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2014 }
2015 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2016 return;
2017 }
2018 r = _regions->next();
2019 }
2020 }
2021 };
2022
2023 void ShenandoahHeap::update_heap_references(bool concurrent) {
2024 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2025
2026 if (concurrent) {
2027 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator);
2028 workers()->run_task(&task);
2029 } else {
2030 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
2031 workers()->run_task(&task);
2032 }
2033 }
2034
2035
2036 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2037 private:
2038 ShenandoahHeapLock* const _lock;
2039
2040 public:
2041 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2042
2043 void heap_region_do(ShenandoahHeapRegion* r) {
2044 // Drop unnecessary "pinned" state from regions that does not have CP marks
2045 // anymore, as this would allow trashing them.
2046
2047 if (r->is_active()) {
2048 if (r->is_pinned()) {
2049 if (r->pin_count() == 0) {
2050 ShenandoahHeapLocker locker(_lock);
2051 r->make_unpinned();
2052 }
2053 } else {
2054 if (r->pin_count() > 0) {
2055 ShenandoahHeapLocker locker(_lock);
2056 r->make_pinned();
2057 }
2058 }
2059 }
2060 }
2061
2062 bool is_thread_safe() { return true; }
2063 };
2064
2065 void ShenandoahHeap::update_heap_region_states(bool concurrent) {
2066 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2067 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2068
2069 {
2070 ShenandoahGCPhase phase(concurrent ?
2071 ShenandoahPhaseTimings::final_update_refs_update_region_states :
2072 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states);
2073 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2074 parallel_heap_region_iterate(&cl);
2075
2076 assert_pinned_region_status();
2077 }
2078
2079 {
2080 ShenandoahGCPhase phase(concurrent ?
2081 ShenandoahPhaseTimings::final_update_refs_trash_cset :
2082 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset);
2083 trash_cset_regions();
2084 }
2085 }
2086
2087 void ShenandoahHeap::rebuild_free_set(bool concurrent) {
2088 {
2089 ShenandoahGCPhase phase(concurrent ?
2090 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
2091 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
2092 ShenandoahHeapLocker locker(lock());
2093 _free_set->rebuild();
2094 }
2095 }
2096
2097 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2098 print_on(st);
2099 st->cr();
2100 print_heap_regions_on(st);
2101 }
2102
2103 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2104 size_t slice = r->index() / _bitmap_regions_per_slice;
2105
2106 size_t regions_from = _bitmap_regions_per_slice * slice;
2107 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2108 for (size_t g = regions_from; g < regions_to; g++) {
2109 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2110 if (skip_self && g == r->index()) continue;
2111 if (get_region(g)->is_committed()) {
2112 return true;
2113 }
2114 }
2115 return false;
2116 }
2117
2118 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2119 shenandoah_assert_heaplocked();
2120
2121 // Bitmaps in special regions do not need commits
2122 if (_bitmap_region_special) {
2123 return true;
2124 }
2125
2126 if (is_bitmap_slice_committed(r, true)) {
2127 // Some other region from the group is already committed, meaning the bitmap
2128 // slice is already committed, we exit right away.
2129 return true;
2130 }
2131
2132 // Commit the bitmap slice:
2133 size_t slice = r->index() / _bitmap_regions_per_slice;
2134 size_t off = _bitmap_bytes_per_slice * slice;
2135 size_t len = _bitmap_bytes_per_slice;
2136 char* start = (char*) _bitmap_region.start() + off;
2137
2138 if (!os::commit_memory(start, len, false)) {
2139 return false;
2140 }
2141
2142 if (AlwaysPreTouch) {
2143 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size);
2144 }
2145
2146 return true;
2147 }
2148
2149 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2150 shenandoah_assert_heaplocked();
2151
2152 // Bitmaps in special regions do not need uncommits
2153 if (_bitmap_region_special) {
2154 return true;
2155 }
2156
2157 if (is_bitmap_slice_committed(r, true)) {
2158 // Some other region from the group is still committed, meaning the bitmap
2159 // slice is should stay committed, exit right away.
2160 return true;
2161 }
2162
2163 // Uncommit the bitmap slice:
2164 size_t slice = r->index() / _bitmap_regions_per_slice;
2165 size_t off = _bitmap_bytes_per_slice * slice;
2166 size_t len = _bitmap_bytes_per_slice;
2167 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2168 return false;
2169 }
2170 return true;
2171 }
2172
2173 void ShenandoahHeap::safepoint_synchronize_begin() {
2174 SuspendibleThreadSet::synchronize();
2175 }
2176
2177 void ShenandoahHeap::safepoint_synchronize_end() {
2178 SuspendibleThreadSet::desynchronize();
2179 }
2180
2181 void ShenandoahHeap::entry_uncommit(double shrink_before, size_t shrink_until) {
2182 static const char *msg = "Concurrent uncommit";
2183 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
2184 EventMark em("%s", msg);
2185
2186 op_uncommit(shrink_before, shrink_until);
2187 }
2188
2189 void ShenandoahHeap::try_inject_alloc_failure() {
2190 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2191 _inject_alloc_failure.set();
2192 os::naked_short_sleep(1);
2193 if (cancelled_gc()) {
2194 log_info(gc)("Allocation failure was successfully injected");
2195 }
2196 }
2197 }
2198
2199 bool ShenandoahHeap::should_inject_alloc_failure() {
2200 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2201 }
2202
2203 void ShenandoahHeap::initialize_serviceability() {
2204 _memory_pool = new ShenandoahMemoryPool(this);
2205 _cycle_memory_manager.add_pool(_memory_pool);
2206 _stw_memory_manager.add_pool(_memory_pool);
2207 }
2208
2209 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2210 GrowableArray<GCMemoryManager*> memory_managers(2);
2211 memory_managers.append(&_cycle_memory_manager);
2212 memory_managers.append(&_stw_memory_manager);
2213 return memory_managers;
2214 }
2215
2216 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2217 GrowableArray<MemoryPool*> memory_pools(1);
2218 memory_pools.append(_memory_pool);
2219 return memory_pools;
2220 }
2221
2222 MemoryUsage ShenandoahHeap::memory_usage() {
2223 return _memory_pool->get_memory_usage();
2224 }
2225
2226 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2227 _heap(ShenandoahHeap::heap()),
2228 _index(0) {}
2229
2230 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2231 _heap(heap),
2232 _index(0) {}
2233
2234 void ShenandoahRegionIterator::reset() {
2235 _index = 0;
2236 }
2237
2238 bool ShenandoahRegionIterator::has_next() const {
2239 return _index < _heap->num_regions();
2240 }
2241
2242 char ShenandoahHeap::gc_state() const {
2243 return _gc_state.raw_value();
2244 }
2245
2246 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2247 #ifdef ASSERT
2248 assert(_liveness_cache != nullptr, "sanity");
2249 assert(worker_id < _max_workers, "sanity");
2250 for (uint i = 0; i < num_regions(); i++) {
2251 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2252 }
2253 #endif
2254 return _liveness_cache[worker_id];
2255 }
2256
2257 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2258 assert(worker_id < _max_workers, "sanity");
2259 assert(_liveness_cache != nullptr, "sanity");
2260 ShenandoahLiveData* ld = _liveness_cache[worker_id];
2261 for (uint i = 0; i < num_regions(); i++) {
2262 ShenandoahLiveData live = ld[i];
2263 if (live > 0) {
2264 ShenandoahHeapRegion* r = get_region(i);
2265 r->increase_live_data_gc_words(live);
2266 ld[i] = 0;
2267 }
2268 }
2269 }
2270
2271 bool ShenandoahHeap::requires_barriers(stackChunkOop obj) const {
2272 if (is_idle()) return false;
2273
2274 // Objects allocated after marking start are implicitly alive, don't need any barriers during
2275 // marking phase.
2276 if (is_concurrent_mark_in_progress() &&
2277 !marking_context()->allocated_after_mark_start(obj)) {
2278 return true;
2279 }
2280
2281 // Can not guarantee obj is deeply good.
2282 if (has_forwarded_objects()) {
2283 return true;
2284 }
2285
2286 return false;
2287 }