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.
842 //
843 // Then, we need to make sure the allocation was retried after at least one
844 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
845
846 size_t tries = 0;
847
848 while (result == nullptr && _progress_last_gc.is_set()) {
849 tries++;
850 control_thread()->handle_alloc_failure(req);
851 result = allocate_memory_under_lock(req, in_new_region);
852 }
853
854 while (result == nullptr && tries <= ShenandoahFullGCThreshold) {
855 tries++;
856 control_thread()->handle_alloc_failure(req);
857 result = allocate_memory_under_lock(req, in_new_region);
858 }
859
860 } else {
861 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
862 result = allocate_memory_under_lock(req, in_new_region);
863 // Do not call handle_alloc_failure() here, because we cannot block.
864 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
865 }
866
867 if (in_new_region) {
868 control_thread()->notify_heap_changed();
869 }
870
871 if (result != nullptr) {
872 size_t requested = req.size();
873 size_t actual = req.actual_size();
874
875 assert (req.is_lab_alloc() || (requested == actual),
876 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
877 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
878
879 if (req.is_mutator_alloc()) {
880 notify_mutator_alloc_words(actual, false);
881
882 // If we requested more than we were granted, give the rest back to pacer.
883 // This only matters if we are in the same pacing epoch: do not try to unpace
884 // over the budget for the other phase.
885 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
886 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
887 }
888 } else {
889 increase_used(actual*HeapWordSize);
890 }
891 }
892
893 return result;
894 }
895
896 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
897 ShenandoahHeapLocker locker(lock());
898 return _free_set->allocate(req, in_new_region);
899 }
900
901 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
902 bool* gc_overhead_limit_was_exceeded) {
903 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
904 return allocate_memory(req);
905 }
906
907 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
908 size_t size,
909 Metaspace::MetadataType mdtype) {
910 MetaWord* result;
911
912 // Inform metaspace OOM to GC heuristics if class unloading is possible.
913 if (heuristics()->can_unload_classes()) {
914 ShenandoahHeuristics* h = heuristics();
915 h->record_metaspace_oom();
916 }
917
918 // Expand and retry allocation
919 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
920 if (result != nullptr) {
921 return result;
922 }
923
924 // Start full GC
925 collect(GCCause::_metadata_GC_clear_soft_refs);
926
927 // Retry allocation
928 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
929 if (result != nullptr) {
930 return result;
931 }
932
933 // Expand and retry allocation
934 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
935 if (result != nullptr) {
936 return result;
937 }
938
939 // Out of memory
940 return nullptr;
941 }
942
943 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
944 private:
945 ShenandoahHeap* const _heap;
946 Thread* const _thread;
947 public:
948 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
949 _heap(heap), _thread(Thread::current()) {}
950
951 void do_object(oop p) {
952 shenandoah_assert_marked(nullptr, p);
953 if (!p->is_forwarded()) {
954 _heap->evacuate_object(p, _thread);
955 }
956 }
957 };
958
959 class ShenandoahEvacuationTask : public WorkerTask {
960 private:
961 ShenandoahHeap* const _sh;
962 ShenandoahCollectionSet* const _cs;
963 bool _concurrent;
964 public:
965 ShenandoahEvacuationTask(ShenandoahHeap* sh,
966 ShenandoahCollectionSet* cs,
967 bool concurrent) :
968 WorkerTask("Shenandoah Evacuation"),
969 _sh(sh),
970 _cs(cs),
971 _concurrent(concurrent)
972 {}
973
974 void work(uint worker_id) {
975 if (_concurrent) {
976 ShenandoahConcurrentWorkerSession worker_session(worker_id);
977 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
978 ShenandoahEvacOOMScope oom_evac_scope;
979 do_work();
980 } else {
981 ShenandoahParallelWorkerSession worker_session(worker_id);
982 ShenandoahEvacOOMScope oom_evac_scope;
983 do_work();
984 }
985 }
986
987 private:
988 void do_work() {
989 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
990 ShenandoahHeapRegion* r;
991 while ((r =_cs->claim_next()) != nullptr) {
992 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
993 _sh->marked_object_iterate(r, &cl);
994
995 if (ShenandoahPacing) {
996 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
997 }
998
999 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1000 break;
1001 }
1002 }
1003 }
1004 };
1005
1006 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
1007 ShenandoahEvacuationTask task(this, _collection_set, concurrent);
1008 workers()->run_task(&task);
1009 }
1010
1011 void ShenandoahHeap::trash_cset_regions() {
1012 ShenandoahHeapLocker locker(lock());
1013
1014 ShenandoahCollectionSet* set = collection_set();
1015 ShenandoahHeapRegion* r;
1016 set->clear_current_index();
1017 while ((r = set->next()) != nullptr) {
1018 r->make_trash();
1019 }
1020 collection_set()->clear();
1021 }
1022
1023 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1024 st->print_cr("Heap Regions:");
1025 st->print_cr("Region state: EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HP=pinned humongous start");
1026 st->print_cr(" HC=humongous continuation, CS=collection set, TR=trash, P=pinned, CSP=pinned collection set");
1027 st->print_cr("BTE=bottom/top/end, TAMS=top-at-mark-start");
1028 st->print_cr("UWM=update watermark, U=used");
1029 st->print_cr("T=TLAB allocs, G=GCLAB allocs");
1030 st->print_cr("S=shared allocs, L=live data");
1031 st->print_cr("CP=critical pins");
1032
1033 for (size_t i = 0; i < num_regions(); i++) {
1034 get_region(i)->print_on(st);
1035 }
1036 }
1037
1038 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1039 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1040
1041 oop humongous_obj = cast_to_oop(start->bottom());
1042 size_t size = humongous_obj->size();
1043 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1044 size_t index = start->index() + required_regions - 1;
1045
1046 assert(!start->has_live(), "liveness must be zero");
1047
1048 for(size_t i = 0; i < required_regions; i++) {
1049 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1050 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1051 ShenandoahHeapRegion* region = get_region(index --);
1052
1053 assert(region->is_humongous(), "expect correct humongous start or continuation");
1054 assert(!region->is_cset(), "Humongous region should not be in collection set");
1055
1056 region->make_trash_immediate();
1057 }
1058 }
1059
1060 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1061 public:
1062 ShenandoahCheckCleanGCLABClosure() {}
1063 void do_thread(Thread* thread) {
1064 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1065 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1066 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1067 }
1068 };
1069
1070 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1071 private:
1072 bool const _resize;
1073 public:
1074 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1075 void do_thread(Thread* thread) {
1076 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1077 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1078 gclab->retire();
1079 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1080 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1081 }
1082 }
1083 };
1084
1085 void ShenandoahHeap::labs_make_parsable() {
1086 assert(UseTLAB, "Only call with UseTLAB");
1087
1088 ShenandoahRetireGCLABClosure cl(false);
1089
1090 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1091 ThreadLocalAllocBuffer& tlab = t->tlab();
1092 tlab.make_parsable();
1093 cl.do_thread(t);
1094 }
1095
1096 workers()->threads_do(&cl);
1097 }
1098
1099 void ShenandoahHeap::tlabs_retire(bool resize) {
1100 assert(UseTLAB, "Only call with UseTLAB");
1101 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1102
1103 ThreadLocalAllocStats stats;
1104
1105 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1106 ThreadLocalAllocBuffer& tlab = t->tlab();
1107 tlab.retire(&stats);
1108 if (resize) {
1109 tlab.resize();
1110 }
1111 }
1112
1113 stats.publish();
1114
1115 #ifdef ASSERT
1116 ShenandoahCheckCleanGCLABClosure cl;
1117 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1118 cl.do_thread(t);
1119 }
1120 workers()->threads_do(&cl);
1121 #endif
1122 }
1123
1124 void ShenandoahHeap::gclabs_retire(bool resize) {
1125 assert(UseTLAB, "Only call with UseTLAB");
1126 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1127
1128 ShenandoahRetireGCLABClosure cl(resize);
1129 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1130 cl.do_thread(t);
1131 }
1132 workers()->threads_do(&cl);
1133
1134 if (safepoint_workers() != nullptr) {
1135 safepoint_workers()->threads_do(&cl);
1136 }
1137 }
1138
1139 // Returns size in bytes
1140 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1141 if (ShenandoahElasticTLAB) {
1142 // With Elastic TLABs, return the max allowed size, and let the allocation path
1143 // figure out the safe size for current allocation.
1144 return ShenandoahHeapRegion::max_tlab_size_bytes();
1145 } else {
1146 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1147 }
1148 }
1149
1150 size_t ShenandoahHeap::max_tlab_size() const {
1151 // Returns size in words
1152 return ShenandoahHeapRegion::max_tlab_size_words();
1153 }
1154
1155 void ShenandoahHeap::collect(GCCause::Cause cause) {
1156 control_thread()->request_gc(cause);
1157 }
1158
1159 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1160 //assert(false, "Shouldn't need to do full collections");
1161 }
1162
1163 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1164 ShenandoahHeapRegion* r = heap_region_containing(addr);
1165 if (r != nullptr) {
1166 return r->block_start(addr);
1167 }
1168 return nullptr;
1169 }
1170
1171 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1172 ShenandoahHeapRegion* r = heap_region_containing(addr);
1173 return r->block_is_obj(addr);
1174 }
1175
1176 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1177 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1178 }
1179
1180 void ShenandoahHeap::prepare_for_verify() {
1181 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1182 labs_make_parsable();
1183 }
1184 }
1185
1186 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1187 tcl->do_thread(_control_thread);
1188 workers()->threads_do(tcl);
1189 if (_safepoint_workers != nullptr) {
1190 _safepoint_workers->threads_do(tcl);
1191 }
1192 }
1193
1194 void ShenandoahHeap::print_tracing_info() const {
1195 LogTarget(Info, gc, stats) lt;
1196 if (lt.is_enabled()) {
1197 ResourceMark rm;
1198 LogStream ls(lt);
1199
1200 phase_timings()->print_global_on(&ls);
1201
1202 ls.cr();
1203 ls.cr();
1204
1205 shenandoah_policy()->print_gc_stats(&ls);
1206
1207 ls.cr();
1208 ls.cr();
1209 }
1210 }
1211
1212 void ShenandoahHeap::verify(VerifyOption vo) {
1213 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1214 if (ShenandoahVerify) {
1215 verifier()->verify_generic(vo);
1216 } else {
1217 // TODO: Consider allocating verification bitmaps on demand,
1218 // and turn this on unconditionally.
1219 }
1220 }
1221 }
1222 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1223 return _free_set->capacity();
1224 }
1225
1226 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1227 private:
1228 MarkBitMap* _bitmap;
1229 ShenandoahScanObjectStack* _oop_stack;
1230 ShenandoahHeap* const _heap;
1231 ShenandoahMarkingContext* const _marking_context;
1232
1233 template <class T>
1234 void do_oop_work(T* p) {
1235 T o = RawAccess<>::oop_load(p);
1236 if (!CompressedOops::is_null(o)) {
1237 oop obj = CompressedOops::decode_not_null(o);
1238 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1239 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1240 return;
1241 }
1242 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1243
1244 assert(oopDesc::is_oop(obj), "must be a valid oop");
1245 if (!_bitmap->is_marked(obj)) {
1246 _bitmap->mark(obj);
1247 _oop_stack->push(obj);
1248 }
1249 }
1250 }
1251 public:
1252 ObjectIterateScanRootClosure(MarkBitMap* bitmap, ShenandoahScanObjectStack* oop_stack) :
1253 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1254 _marking_context(_heap->marking_context()) {}
1255 void do_oop(oop* p) { do_oop_work(p); }
1256 void do_oop(narrowOop* p) { do_oop_work(p); }
1257 };
1258
1259 /*
1260 * This is public API, used in preparation of object_iterate().
1261 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1262 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1263 * control, we call SH::tlabs_retire, SH::gclabs_retire.
1264 */
1265 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1266 // No-op.
1267 }
1268
1269 /*
1270 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1271 *
1272 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1273 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1274 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1275 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1276 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1277 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1278 * wiped the bitmap in preparation for next marking).
1279 *
1280 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1281 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1282 * is allowed to report dead objects, but is not required to do so.
1283 */
1284 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1285 // Reset bitmap
1286 if (!prepare_aux_bitmap_for_iteration())
1287 return;
1288
1289 ShenandoahScanObjectStack oop_stack;
1290 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1291 // Seed the stack with root scan
1292 scan_roots_for_iteration(&oop_stack, &oops);
1293
1294 // Work through the oop stack to traverse heap
1295 while (! oop_stack.is_empty()) {
1296 oop obj = oop_stack.pop();
1297 assert(oopDesc::is_oop(obj), "must be a valid oop");
1298 cl->do_object(obj);
1299 obj->oop_iterate(&oops);
1300 }
1301
1302 assert(oop_stack.is_empty(), "should be empty");
1303 // Reclaim bitmap
1304 reclaim_aux_bitmap_for_iteration();
1305 }
1306
1307 bool ShenandoahHeap::prepare_aux_bitmap_for_iteration() {
1308 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1309
1310 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1311 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1312 return false;
1313 }
1314 // Reset bitmap
1315 _aux_bit_map.clear();
1316 return true;
1317 }
1318
1319 void ShenandoahHeap::scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops) {
1320 // Process GC roots according to current GC cycle
1321 // This populates the work stack with initial objects
1322 // It is important to relinquish the associated locks before diving
1323 // into heap dumper
1324 uint n_workers = safepoint_workers() != nullptr ? safepoint_workers()->active_workers() : 1;
1325 ShenandoahHeapIterationRootScanner rp(n_workers);
1326 rp.roots_do(oops);
1327 }
1328
1329 void ShenandoahHeap::reclaim_aux_bitmap_for_iteration() {
1330 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1331 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1332 }
1333 }
1334
1335 // Closure for parallelly iterate objects
1336 class ShenandoahObjectIterateParScanClosure : public BasicOopIterateClosure {
1337 private:
1338 MarkBitMap* _bitmap;
1339 ShenandoahObjToScanQueue* _queue;
1340 ShenandoahHeap* const _heap;
1341 ShenandoahMarkingContext* const _marking_context;
1342
1343 template <class T>
1344 void do_oop_work(T* p) {
1345 T o = RawAccess<>::oop_load(p);
1346 if (!CompressedOops::is_null(o)) {
1347 oop obj = CompressedOops::decode_not_null(o);
1348 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1349 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1350 return;
1351 }
1352 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1353
1354 assert(oopDesc::is_oop(obj), "Must be a valid oop");
1355 if (_bitmap->par_mark(obj)) {
1356 _queue->push(ShenandoahMarkTask(obj));
1357 }
1358 }
1359 }
1360 public:
1361 ShenandoahObjectIterateParScanClosure(MarkBitMap* bitmap, ShenandoahObjToScanQueue* q) :
1362 _bitmap(bitmap), _queue(q), _heap(ShenandoahHeap::heap()),
1363 _marking_context(_heap->marking_context()) {}
1364 void do_oop(oop* p) { do_oop_work(p); }
1365 void do_oop(narrowOop* p) { do_oop_work(p); }
1366 };
1367
1368 // Object iterator for parallel heap iteraion.
1369 // The root scanning phase happenes in construction as a preparation of
1370 // parallel marking queues.
1371 // Every worker processes it's own marking queue. work-stealing is used
1372 // to balance workload.
1373 class ShenandoahParallelObjectIterator : public ParallelObjectIteratorImpl {
1374 private:
1375 uint _num_workers;
1376 bool _init_ready;
1377 MarkBitMap* _aux_bit_map;
1378 ShenandoahHeap* _heap;
1379 ShenandoahScanObjectStack _roots_stack; // global roots stack
1380 ShenandoahObjToScanQueueSet* _task_queues;
1381 public:
1382 ShenandoahParallelObjectIterator(uint num_workers, MarkBitMap* bitmap) :
1383 _num_workers(num_workers),
1384 _init_ready(false),
1385 _aux_bit_map(bitmap),
1386 _heap(ShenandoahHeap::heap()) {
1387 // Initialize bitmap
1388 _init_ready = _heap->prepare_aux_bitmap_for_iteration();
1389 if (!_init_ready) {
1390 return;
1391 }
1392
1393 ObjectIterateScanRootClosure oops(_aux_bit_map, &_roots_stack);
1394 _heap->scan_roots_for_iteration(&_roots_stack, &oops);
1395
1396 _init_ready = prepare_worker_queues();
1397 }
1398
1399 ~ShenandoahParallelObjectIterator() {
1400 // Reclaim bitmap
1401 _heap->reclaim_aux_bitmap_for_iteration();
1402 // Reclaim queue for workers
1403 if (_task_queues!= nullptr) {
1404 for (uint i = 0; i < _num_workers; ++i) {
1405 ShenandoahObjToScanQueue* q = _task_queues->queue(i);
1406 if (q != nullptr) {
1407 delete q;
1408 _task_queues->register_queue(i, nullptr);
1409 }
1410 }
1411 delete _task_queues;
1412 _task_queues = nullptr;
1413 }
1414 }
1415
1416 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
1417 if (_init_ready) {
1418 object_iterate_parallel(cl, worker_id, _task_queues);
1419 }
1420 }
1421
1422 private:
1423 // Divide global root_stack into worker queues
1424 bool prepare_worker_queues() {
1425 _task_queues = new ShenandoahObjToScanQueueSet((int) _num_workers);
1426 // Initialize queues for every workers
1427 for (uint i = 0; i < _num_workers; ++i) {
1428 ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue();
1429 _task_queues->register_queue(i, task_queue);
1430 }
1431 // Divide roots among the workers. Assume that object referencing distribution
1432 // is related with root kind, use round-robin to make every worker have same chance
1433 // to process every kind of roots
1434 size_t roots_num = _roots_stack.size();
1435 if (roots_num == 0) {
1436 // No work to do
1437 return false;
1438 }
1439
1440 for (uint j = 0; j < roots_num; j++) {
1441 uint stack_id = j % _num_workers;
1442 oop obj = _roots_stack.pop();
1443 _task_queues->queue(stack_id)->push(ShenandoahMarkTask(obj));
1444 }
1445 return true;
1446 }
1447
1448 void object_iterate_parallel(ObjectClosure* cl,
1449 uint worker_id,
1450 ShenandoahObjToScanQueueSet* queue_set) {
1451 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1452 assert(queue_set != nullptr, "task queue must not be null");
1453
1454 ShenandoahObjToScanQueue* q = queue_set->queue(worker_id);
1455 assert(q != nullptr, "object iterate queue must not be null");
1456
1457 ShenandoahMarkTask t;
1458 ShenandoahObjectIterateParScanClosure oops(_aux_bit_map, q);
1459
1460 // Work through the queue to traverse heap.
1461 // Steal when there is no task in queue.
1462 while (q->pop(t) || queue_set->steal(worker_id, t)) {
1463 oop obj = t.obj();
1464 assert(oopDesc::is_oop(obj), "must be a valid oop");
1465 cl->do_object(obj);
1466 obj->oop_iterate(&oops);
1467 }
1468 assert(q->is_empty(), "should be empty");
1469 }
1470 };
1471
1472 ParallelObjectIteratorImpl* ShenandoahHeap::parallel_object_iterator(uint workers) {
1473 return new ShenandoahParallelObjectIterator(workers, &_aux_bit_map);
1474 }
1475
1476 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1477 void ShenandoahHeap::keep_alive(oop obj) {
1478 if (is_concurrent_mark_in_progress() && (obj != nullptr)) {
1479 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1480 }
1481 }
1482
1483 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1484 for (size_t i = 0; i < num_regions(); i++) {
1485 ShenandoahHeapRegion* current = get_region(i);
1486 blk->heap_region_do(current);
1487 }
1488 }
1489
1490 class ShenandoahParallelHeapRegionTask : public WorkerTask {
1491 private:
1492 ShenandoahHeap* const _heap;
1493 ShenandoahHeapRegionClosure* const _blk;
1494
1495 shenandoah_padding(0);
1496 volatile size_t _index;
1497 shenandoah_padding(1);
1498
1499 public:
1500 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1501 WorkerTask("Shenandoah Parallel Region Operation"),
1502 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1503
1504 void work(uint worker_id) {
1505 ShenandoahParallelWorkerSession worker_session(worker_id);
1506 size_t stride = ShenandoahParallelRegionStride;
1507
1508 size_t max = _heap->num_regions();
1509 while (Atomic::load(&_index) < max) {
1510 size_t cur = Atomic::fetch_then_add(&_index, stride, memory_order_relaxed);
1511 size_t start = cur;
1512 size_t end = MIN2(cur + stride, max);
1513 if (start >= max) break;
1514
1515 for (size_t i = cur; i < end; i++) {
1516 ShenandoahHeapRegion* current = _heap->get_region(i);
1517 _blk->heap_region_do(current);
1518 }
1519 }
1520 }
1521 };
1522
1523 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1524 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1525 if (num_regions() > ShenandoahParallelRegionStride) {
1526 ShenandoahParallelHeapRegionTask task(blk);
1527 workers()->run_task(&task);
1528 } else {
1529 heap_region_iterate(blk);
1530 }
1531 }
1532
1533 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1534 private:
1535 ShenandoahMarkingContext* const _ctx;
1536 public:
1537 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1538
1539 void heap_region_do(ShenandoahHeapRegion* r) {
1540 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1541 if (r->is_active()) {
1542 // Check if region needs updating its TAMS. We have updated it already during concurrent
1543 // reset, so it is very likely we don't need to do another write here.
1544 if (_ctx->top_at_mark_start(r) != r->top()) {
1545 _ctx->capture_top_at_mark_start(r);
1546 }
1547 } else {
1548 assert(_ctx->top_at_mark_start(r) == r->top(),
1549 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1550 }
1551 }
1552
1553 bool is_thread_safe() { return true; }
1554 };
1555
1556 class ShenandoahRendezvousClosure : public HandshakeClosure {
1557 public:
1558 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
1559 inline void do_thread(Thread* thread) {}
1560 };
1561
1562 void ShenandoahHeap::rendezvous_threads() {
1563 ShenandoahRendezvousClosure cl;
1564 Handshake::execute(&cl);
1565 }
1566
1567 void ShenandoahHeap::recycle_trash() {
1568 free_set()->recycle_trash();
1569 }
1570
1571 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1572 private:
1573 ShenandoahMarkingContext* const _ctx;
1574 public:
1575 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1576
1577 void heap_region_do(ShenandoahHeapRegion* r) {
1578 if (r->is_active()) {
1579 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1580 // anyway to capture any updates that happened since now.
1581 r->clear_live_data();
1582 _ctx->capture_top_at_mark_start(r);
1583 }
1584 }
1585
1586 bool is_thread_safe() { return true; }
1587 };
1588
1589 void ShenandoahHeap::prepare_gc() {
1590 reset_mark_bitmap();
1591
1592 ShenandoahResetUpdateRegionStateClosure cl;
1593 parallel_heap_region_iterate(&cl);
1594 }
1595
1596 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1597 private:
1598 ShenandoahMarkingContext* const _ctx;
1599 ShenandoahHeapLock* const _lock;
1600
1601 public:
1602 ShenandoahFinalMarkUpdateRegionStateClosure() :
1603 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1604
1605 void heap_region_do(ShenandoahHeapRegion* r) {
1606 if (r->is_active()) {
1607 // All allocations past TAMS are implicitly live, adjust the region data.
1608 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1609 HeapWord *tams = _ctx->top_at_mark_start(r);
1610 HeapWord *top = r->top();
1611 if (top > tams) {
1612 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1613 }
1614
1615 // We are about to select the collection set, make sure it knows about
1616 // current pinning status. Also, this allows trashing more regions that
1617 // now have their pinning status dropped.
1618 if (r->is_pinned()) {
1619 if (r->pin_count() == 0) {
1620 ShenandoahHeapLocker locker(_lock);
1621 r->make_unpinned();
1622 }
1623 } else {
1624 if (r->pin_count() > 0) {
1625 ShenandoahHeapLocker locker(_lock);
1626 r->make_pinned();
1627 }
1628 }
1629
1630 // Remember limit for updating refs. It's guaranteed that we get no
1631 // from-space-refs written from here on.
1632 r->set_update_watermark_at_safepoint(r->top());
1633 } else {
1634 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1635 assert(_ctx->top_at_mark_start(r) == r->top(),
1636 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1637 }
1638 }
1639
1640 bool is_thread_safe() { return true; }
1641 };
1642
1643 void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) {
1644 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
1645 {
1646 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states :
1647 ShenandoahPhaseTimings::degen_gc_final_update_region_states);
1648 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1649 parallel_heap_region_iterate(&cl);
1650
1651 assert_pinned_region_status();
1652 }
1653
1654 {
1655 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset :
1656 ShenandoahPhaseTimings::degen_gc_choose_cset);
1657 ShenandoahHeapLocker locker(lock());
1658 _collection_set->clear();
1659 heuristics()->choose_collection_set(_collection_set);
1660 }
1661
1662 {
1663 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset :
1664 ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset);
1665 ShenandoahHeapLocker locker(lock());
1666 _free_set->rebuild();
1667 }
1668 }
1669
1670 void ShenandoahHeap::do_class_unloading() {
1671 _unloader.unload();
1672 }
1673
1674 void ShenandoahHeap::stw_weak_refs(bool full_gc) {
1675 // Weak refs processing
1676 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
1677 : ShenandoahPhaseTimings::degen_gc_weakrefs;
1678 ShenandoahTimingsTracker t(phase);
1679 ShenandoahGCWorkerPhase worker_phase(phase);
1680 ref_processor()->process_references(phase, workers(), false /* concurrent */);
1681 }
1682
1683 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
1684 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1685
1686 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
1687 // make them parsable for update code to work correctly. Plus, we can compute new sizes
1688 // for future GCLABs here.
1689 if (UseTLAB) {
1690 ShenandoahGCPhase phase(concurrent ?
1691 ShenandoahPhaseTimings::init_update_refs_manage_gclabs :
1692 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs);
1693 gclabs_retire(ResizeTLAB);
1694 }
1695
1696 _update_refs_iterator.reset();
1697 }
1698
1699 void ShenandoahHeap::set_gc_state_all_threads(char state) {
1700 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1701 ShenandoahThreadLocalData::set_gc_state(t, state);
1702 }
1703 }
1704
1705 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1706 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1707 _gc_state.set_cond(mask, value);
1708 set_gc_state_all_threads(_gc_state.raw_value());
1709 }
1710
1711 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1712 assert(!has_forwarded_objects(), "Not expected before/after mark phase");
1713 set_gc_state_mask(MARKING, in_progress);
1714 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1715 }
1716
1717 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1718 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1719 set_gc_state_mask(EVACUATION, in_progress);
1720 }
1721
1722 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
1723 if (in_progress) {
1724 _concurrent_strong_root_in_progress.set();
1725 } else {
1726 _concurrent_strong_root_in_progress.unset();
1727 }
1728 }
1729
1730 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) {
1731 set_gc_state_mask(WEAK_ROOTS, cond);
1732 }
1733
1734 GCTracer* ShenandoahHeap::tracer() {
1735 return shenandoah_policy()->tracer();
1736 }
1737
1738 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1739 return _free_set->used();
1740 }
1741
1742 bool ShenandoahHeap::try_cancel_gc() {
1743 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1744 return prev == CANCELLABLE;
1745 }
1746
1747 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1748 if (try_cancel_gc()) {
1749 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1750 log_info(gc)("%s", msg.buffer());
1751 Events::log(Thread::current(), "%s", msg.buffer());
1752 }
1753 }
1754
1755 uint ShenandoahHeap::max_workers() {
1756 return _max_workers;
1757 }
1758
1759 void ShenandoahHeap::stop() {
1760 // The shutdown sequence should be able to terminate when GC is running.
1761
1762 // Step 0. Notify policy to disable event recording.
1763 _shenandoah_policy->record_shutdown();
1764
1765 // Step 1. Notify control thread that we are in shutdown.
1766 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1767 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1768 control_thread()->prepare_for_graceful_shutdown();
1769
1770 // Step 2. Notify GC workers that we are cancelling GC.
1771 cancel_gc(GCCause::_shenandoah_stop_vm);
1772
1773 // Step 3. Wait until GC worker exits normally.
1774 control_thread()->stop();
1775 }
1776
1777 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
1778 if (!unload_classes()) return;
1779 // Unload classes and purge SystemDictionary.
1780 {
1781 ShenandoahPhaseTimings::Phase phase = full_gc ?
1782 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1783 ShenandoahPhaseTimings::degen_gc_purge_class_unload;
1784 ShenandoahIsAliveSelector is_alive;
1785 CodeCache::UnloadingScope scope(is_alive.is_alive_closure());
1786 ShenandoahGCPhase gc_phase(phase);
1787 ShenandoahGCWorkerPhase worker_phase(phase);
1788 bool purged_class = SystemDictionary::do_unloading(gc_timer());
1789
1790 uint num_workers = _workers->active_workers();
1791 ShenandoahClassUnloadingTask unlink_task(phase, num_workers, purged_class);
1792 _workers->run_task(&unlink_task);
1793 }
1794
1795 {
1796 ShenandoahGCPhase phase(full_gc ?
1797 ShenandoahPhaseTimings::full_gc_purge_cldg :
1798 ShenandoahPhaseTimings::degen_gc_purge_cldg);
1799 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
1800 }
1801 // Resize and verify metaspace
1802 MetaspaceGC::compute_new_size();
1803 DEBUG_ONLY(MetaspaceUtils::verify();)
1804 }
1805
1806 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
1807 // so they should not have forwarded oops.
1808 // However, we do need to "null" dead oops in the roots, if can not be done
1809 // in concurrent cycles.
1810 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
1811 uint num_workers = _workers->active_workers();
1812 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
1813 ShenandoahPhaseTimings::full_gc_purge_weak_par :
1814 ShenandoahPhaseTimings::degen_gc_purge_weak_par;
1815 ShenandoahGCPhase phase(timing_phase);
1816 ShenandoahGCWorkerPhase worker_phase(timing_phase);
1817 // Cleanup weak roots
1818 if (has_forwarded_objects()) {
1819 ShenandoahForwardedIsAliveClosure is_alive;
1820 ShenandoahUpdateRefsClosure keep_alive;
1821 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
1822 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers);
1823 _workers->run_task(&cleaning_task);
1824 } else {
1825 ShenandoahIsAliveClosure is_alive;
1826 #ifdef ASSERT
1827 ShenandoahAssertNotForwardedClosure verify_cl;
1828 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
1829 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers);
1830 #else
1831 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
1832 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers);
1833 #endif
1834 _workers->run_task(&cleaning_task);
1835 }
1836 }
1837
1838 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
1839 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1840 assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC");
1841 ShenandoahGCPhase phase(full_gc ?
1842 ShenandoahPhaseTimings::full_gc_purge :
1843 ShenandoahPhaseTimings::degen_gc_purge);
1844 stw_weak_refs(full_gc);
1845 stw_process_weak_roots(full_gc);
1846 stw_unload_classes(full_gc);
1847 }
1848
1849 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
1850 set_gc_state_mask(HAS_FORWARDED, cond);
1851 }
1852
1853 void ShenandoahHeap::set_unload_classes(bool uc) {
1854 _unload_classes.set_cond(uc);
1855 }
1856
1857 bool ShenandoahHeap::unload_classes() const {
1858 return _unload_classes.is_set();
1859 }
1860
1861 address ShenandoahHeap::in_cset_fast_test_addr() {
1862 ShenandoahHeap* heap = ShenandoahHeap::heap();
1863 assert(heap->collection_set() != nullptr, "Sanity");
1864 return (address) heap->collection_set()->biased_map_address();
1865 }
1866
1867 address ShenandoahHeap::cancelled_gc_addr() {
1868 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
1869 }
1870
1871 address ShenandoahHeap::gc_state_addr() {
1872 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
1873 }
1874
1875 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
1876 return Atomic::load(&_bytes_allocated_since_gc_start);
1877 }
1878
1879 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
1880 Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0);
1881 }
1882
1883 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
1884 _degenerated_gc_in_progress.set_cond(in_progress);
1885 }
1886
1887 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
1888 _full_gc_in_progress.set_cond(in_progress);
1889 }
1890
1891 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
1892 assert (is_full_gc_in_progress(), "should be");
1893 _full_gc_move_in_progress.set_cond(in_progress);
1894 }
1895
1896 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
1897 set_gc_state_mask(UPDATEREFS, in_progress);
1898 }
1899
1900 void ShenandoahHeap::register_nmethod(nmethod* nm) {
1901 ShenandoahCodeRoots::register_nmethod(nm);
1902 }
1903
1904 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
1905 ShenandoahCodeRoots::unregister_nmethod(nm);
1906 }
1907
1908 void ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
1909 heap_region_containing(o)->record_pin();
1910 }
1911
1912 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
1913 ShenandoahHeapRegion* r = heap_region_containing(o);
1914 assert(r != nullptr, "Sanity");
1915 assert(r->pin_count() > 0, "Region " SIZE_FORMAT " should have non-zero pins", r->index());
1916 r->record_unpin();
1917 }
1918
1919 void ShenandoahHeap::sync_pinned_region_status() {
1920 ShenandoahHeapLocker locker(lock());
1921
1922 for (size_t i = 0; i < num_regions(); i++) {
1923 ShenandoahHeapRegion *r = get_region(i);
1924 if (r->is_active()) {
1925 if (r->is_pinned()) {
1926 if (r->pin_count() == 0) {
1927 r->make_unpinned();
1928 }
1929 } else {
1930 if (r->pin_count() > 0) {
1931 r->make_pinned();
1932 }
1933 }
1934 }
1935 }
1936
1937 assert_pinned_region_status();
1938 }
1939
1940 #ifdef ASSERT
1941 void ShenandoahHeap::assert_pinned_region_status() {
1942 for (size_t i = 0; i < num_regions(); i++) {
1943 ShenandoahHeapRegion* r = get_region(i);
1944 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
1945 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
1946 }
1947 }
1948 #endif
1949
1950 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
1951 return _gc_timer;
1952 }
1953
1954 void ShenandoahHeap::prepare_concurrent_roots() {
1955 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1956 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1957 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
1958 set_concurrent_weak_root_in_progress(true);
1959 if (unload_classes()) {
1960 _unloader.prepare();
1961 }
1962 }
1963
1964 void ShenandoahHeap::finish_concurrent_roots() {
1965 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1966 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1967 if (unload_classes()) {
1968 _unloader.finish();
1969 }
1970 }
1971
1972 #ifdef ASSERT
1973 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
1974 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
1975
1976 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1977 if (UseDynamicNumberOfGCThreads) {
1978 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
1979 } else {
1980 // Use ParallelGCThreads inside safepoints
1981 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
1982 }
1983 } else {
1984 if (UseDynamicNumberOfGCThreads) {
1985 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
1986 } else {
1987 // Use ConcGCThreads outside safepoints
1988 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
1989 }
1990 }
1991 }
1992 #endif
1993
1994 ShenandoahVerifier* ShenandoahHeap::verifier() {
1995 guarantee(ShenandoahVerify, "Should be enabled");
1996 assert (_verifier != nullptr, "sanity");
1997 return _verifier;
1998 }
1999
2000 template<bool CONCURRENT>
2001 class ShenandoahUpdateHeapRefsTask : public WorkerTask {
2002 private:
2003 ShenandoahHeap* _heap;
2004 ShenandoahRegionIterator* _regions;
2005 public:
2006 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
2007 WorkerTask("Shenandoah Update References"),
2008 _heap(ShenandoahHeap::heap()),
2009 _regions(regions) {
2010 }
2011
2012 void work(uint worker_id) {
2013 if (CONCURRENT) {
2014 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2015 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2016 do_work<ShenandoahConcUpdateRefsClosure>();
2017 } else {
2018 ShenandoahParallelWorkerSession worker_session(worker_id);
2019 do_work<ShenandoahSTWUpdateRefsClosure>();
2020 }
2021 }
2022
2023 private:
2024 template<class T>
2025 void do_work() {
2026 T cl;
2027 ShenandoahHeapRegion* r = _regions->next();
2028 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2029 while (r != nullptr) {
2030 HeapWord* update_watermark = r->get_update_watermark();
2031 assert (update_watermark >= r->bottom(), "sanity");
2032 if (r->is_active() && !r->is_cset()) {
2033 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2034 }
2035 if (ShenandoahPacing) {
2036 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2037 }
2038 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2039 return;
2040 }
2041 r = _regions->next();
2042 }
2043 }
2044 };
2045
2046 void ShenandoahHeap::update_heap_references(bool concurrent) {
2047 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2048
2049 if (concurrent) {
2050 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator);
2051 workers()->run_task(&task);
2052 } else {
2053 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
2054 workers()->run_task(&task);
2055 }
2056 }
2057
2058
2059 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2060 private:
2061 ShenandoahHeapLock* const _lock;
2062
2063 public:
2064 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2065
2066 void heap_region_do(ShenandoahHeapRegion* r) {
2067 // Drop unnecessary "pinned" state from regions that does not have CP marks
2068 // anymore, as this would allow trashing them.
2069
2070 if (r->is_active()) {
2071 if (r->is_pinned()) {
2072 if (r->pin_count() == 0) {
2073 ShenandoahHeapLocker locker(_lock);
2074 r->make_unpinned();
2075 }
2076 } else {
2077 if (r->pin_count() > 0) {
2078 ShenandoahHeapLocker locker(_lock);
2079 r->make_pinned();
2080 }
2081 }
2082 }
2083 }
2084
2085 bool is_thread_safe() { return true; }
2086 };
2087
2088 void ShenandoahHeap::update_heap_region_states(bool concurrent) {
2089 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2090 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2091
2092 {
2093 ShenandoahGCPhase phase(concurrent ?
2094 ShenandoahPhaseTimings::final_update_refs_update_region_states :
2095 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states);
2096 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2097 parallel_heap_region_iterate(&cl);
2098
2099 assert_pinned_region_status();
2100 }
2101
2102 {
2103 ShenandoahGCPhase phase(concurrent ?
2104 ShenandoahPhaseTimings::final_update_refs_trash_cset :
2105 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset);
2106 trash_cset_regions();
2107 }
2108 }
2109
2110 void ShenandoahHeap::rebuild_free_set(bool concurrent) {
2111 {
2112 ShenandoahGCPhase phase(concurrent ?
2113 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
2114 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
2115 ShenandoahHeapLocker locker(lock());
2116 _free_set->rebuild();
2117 }
2118 }
2119
2120 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2121 print_on(st);
2122 st->cr();
2123 print_heap_regions_on(st);
2124 }
2125
2126 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2127 size_t slice = r->index() / _bitmap_regions_per_slice;
2128
2129 size_t regions_from = _bitmap_regions_per_slice * slice;
2130 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2131 for (size_t g = regions_from; g < regions_to; g++) {
2132 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2133 if (skip_self && g == r->index()) continue;
2134 if (get_region(g)->is_committed()) {
2135 return true;
2136 }
2137 }
2138 return false;
2139 }
2140
2141 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2142 shenandoah_assert_heaplocked();
2143
2144 // Bitmaps in special regions do not need commits
2145 if (_bitmap_region_special) {
2146 return true;
2147 }
2148
2149 if (is_bitmap_slice_committed(r, true)) {
2150 // Some other region from the group is already committed, meaning the bitmap
2151 // slice is already committed, we exit right away.
2152 return true;
2153 }
2154
2155 // Commit the bitmap slice:
2156 size_t slice = r->index() / _bitmap_regions_per_slice;
2157 size_t off = _bitmap_bytes_per_slice * slice;
2158 size_t len = _bitmap_bytes_per_slice;
2159 char* start = (char*) _bitmap_region.start() + off;
2160
2161 if (!os::commit_memory(start, len, false)) {
2162 return false;
2163 }
2164
2165 if (AlwaysPreTouch) {
2166 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size);
2167 }
2168
2169 return true;
2170 }
2171
2172 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2173 shenandoah_assert_heaplocked();
2174
2175 // Bitmaps in special regions do not need uncommits
2176 if (_bitmap_region_special) {
2177 return true;
2178 }
2179
2180 if (is_bitmap_slice_committed(r, true)) {
2181 // Some other region from the group is still committed, meaning the bitmap
2182 // slice is should stay committed, exit right away.
2183 return true;
2184 }
2185
2186 // Uncommit the bitmap slice:
2187 size_t slice = r->index() / _bitmap_regions_per_slice;
2188 size_t off = _bitmap_bytes_per_slice * slice;
2189 size_t len = _bitmap_bytes_per_slice;
2190 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2191 return false;
2192 }
2193 return true;
2194 }
2195
2196 void ShenandoahHeap::safepoint_synchronize_begin() {
2197 if (ShenandoahSuspendibleWorkers) {
2198 SuspendibleThreadSet::synchronize();
2199 }
2200 }
2201
2202 void ShenandoahHeap::safepoint_synchronize_end() {
2203 if (ShenandoahSuspendibleWorkers) {
2204 SuspendibleThreadSet::desynchronize();
2205 }
2206 }
2207
2208 void ShenandoahHeap::entry_uncommit(double shrink_before, size_t shrink_until) {
2209 static const char *msg = "Concurrent uncommit";
2210 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
2211 EventMark em("%s", msg);
2212
2213 op_uncommit(shrink_before, shrink_until);
2214 }
2215
2216 void ShenandoahHeap::try_inject_alloc_failure() {
2217 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2218 _inject_alloc_failure.set();
2219 os::naked_short_sleep(1);
2220 if (cancelled_gc()) {
2221 log_info(gc)("Allocation failure was successfully injected");
2222 }
2223 }
2224 }
2225
2226 bool ShenandoahHeap::should_inject_alloc_failure() {
2227 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2228 }
2229
2230 void ShenandoahHeap::initialize_serviceability() {
2231 _memory_pool = new ShenandoahMemoryPool(this);
2232 _cycle_memory_manager.add_pool(_memory_pool);
2233 _stw_memory_manager.add_pool(_memory_pool);
2234 }
2235
2236 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2237 GrowableArray<GCMemoryManager*> memory_managers(2);
2238 memory_managers.append(&_cycle_memory_manager);
2239 memory_managers.append(&_stw_memory_manager);
2240 return memory_managers;
2241 }
2242
2243 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2244 GrowableArray<MemoryPool*> memory_pools(1);
2245 memory_pools.append(_memory_pool);
2246 return memory_pools;
2247 }
2248
2249 MemoryUsage ShenandoahHeap::memory_usage() {
2250 return _memory_pool->get_memory_usage();
2251 }
2252
2253 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2254 _heap(ShenandoahHeap::heap()),
2255 _index(0) {}
2256
2257 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2258 _heap(heap),
2259 _index(0) {}
2260
2261 void ShenandoahRegionIterator::reset() {
2262 _index = 0;
2263 }
2264
2265 bool ShenandoahRegionIterator::has_next() const {
2266 return _index < _heap->num_regions();
2267 }
2268
2269 char ShenandoahHeap::gc_state() const {
2270 return _gc_state.raw_value();
2271 }
2272
2273 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2274 #ifdef ASSERT
2275 assert(_liveness_cache != nullptr, "sanity");
2276 assert(worker_id < _max_workers, "sanity");
2277 for (uint i = 0; i < num_regions(); i++) {
2278 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2279 }
2280 #endif
2281 return _liveness_cache[worker_id];
2282 }
2283
2284 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2285 assert(worker_id < _max_workers, "sanity");
2286 assert(_liveness_cache != nullptr, "sanity");
2287 ShenandoahLiveData* ld = _liveness_cache[worker_id];
2288 for (uint i = 0; i < num_regions(); i++) {
2289 ShenandoahLiveData live = ld[i];
2290 if (live > 0) {
2291 ShenandoahHeapRegion* r = get_region(i);
2292 r->increase_live_data_gc_words(live);
2293 ld[i] = 0;
2294 }
2295 }
2296 }
2297
2298 bool ShenandoahHeap::requires_barriers(stackChunkOop obj) const {
2299 if (is_idle()) return false;
2300
2301 // Objects allocated after marking start are implicitly alive, don't need any barriers during
2302 // marking phase.
2303 if (is_concurrent_mark_in_progress() &&
2304 !marking_context()->allocated_after_mark_start(obj)) {
2305 return true;
2306 }
2307
2308 // Can not guarantee obj is deeply good.
2309 if (has_forwarded_objects()) {
2310 return true;
2311 }
2312
2313 return false;
2314 }