1 /*
2 * Copyright (c) 2013, 2021, Red Hat, Inc. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.hpp"
27 #include "memory/universe.hpp"
28
29 #include "gc/shared/gcArguments.hpp"
30 #include "gc/shared/gcTimer.hpp"
31 #include "gc/shared/gcTraceTime.inline.hpp"
32 #include "gc/shared/locationPrinter.inline.hpp"
33 #include "gc/shared/memAllocator.hpp"
34 #include "gc/shared/plab.hpp"
35 #include "gc/shared/tlab_globals.hpp"
36
37 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
38 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
39 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
40 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
41 #include "gc/shenandoah/shenandoahConcurrentMark.hpp"
42 #include "gc/shenandoah/shenandoahControlThread.hpp"
43 #include "gc/shenandoah/shenandoahFreeSet.hpp"
44 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
45 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
46 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
47 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
48 #include "gc/shenandoah/shenandoahInitLogger.hpp"
49 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
50 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
51 #include "gc/shenandoah/shenandoahMetrics.hpp"
52 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
53 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
54 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
55 #include "gc/shenandoah/shenandoahPadding.hpp"
56 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
57 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
58 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
59 #include "gc/shenandoah/shenandoahStringDedup.hpp"
60 #include "gc/shenandoah/shenandoahSTWMark.hpp"
61 #include "gc/shenandoah/shenandoahUtils.hpp"
62 #include "gc/shenandoah/shenandoahVerifier.hpp"
63 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
64 #include "gc/shenandoah/shenandoahVMOperations.hpp"
65 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
66 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
67 #include "gc/shenandoah/mode/shenandoahIUMode.hpp"
68 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
69 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
70 #if INCLUDE_JFR
71 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
72 #endif
73
74 #include "classfile/systemDictionary.hpp"
75 #include "memory/classLoaderMetaspace.hpp"
76 #include "memory/metaspaceUtils.hpp"
77 #include "oops/compressedOops.inline.hpp"
78 #include "prims/jvmtiTagMap.hpp"
79 #include "runtime/atomic.hpp"
80 #include "runtime/globals.hpp"
81 #include "runtime/interfaceSupport.inline.hpp"
82 #include "runtime/java.hpp"
83 #include "runtime/orderAccess.hpp"
84 #include "runtime/safepointMechanism.hpp"
85 #include "runtime/vmThread.hpp"
86 #include "services/mallocTracker.hpp"
87 #include "services/memTracker.hpp"
88 #include "utilities/events.hpp"
89 #include "utilities/powerOfTwo.hpp"
90
91 class ShenandoahPretouchHeapTask : public AbstractGangTask {
92 private:
93 ShenandoahRegionIterator _regions;
94 const size_t _page_size;
95 public:
96 ShenandoahPretouchHeapTask(size_t page_size) :
97 AbstractGangTask("Shenandoah Pretouch Heap"),
98 _page_size(page_size) {}
99
100 virtual void work(uint worker_id) {
101 ShenandoahHeapRegion* r = _regions.next();
102 while (r != NULL) {
103 if (r->is_committed()) {
104 os::pretouch_memory(r->bottom(), r->end(), _page_size);
105 }
106 r = _regions.next();
107 }
108 }
109 };
110
111 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
112 private:
113 ShenandoahRegionIterator _regions;
114 char* _bitmap_base;
115 const size_t _bitmap_size;
116 const size_t _page_size;
117 public:
118 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
119 AbstractGangTask("Shenandoah Pretouch Bitmap"),
120 _bitmap_base(bitmap_base),
121 _bitmap_size(bitmap_size),
122 _page_size(page_size) {}
123
124 virtual void work(uint worker_id) {
125 ShenandoahHeapRegion* r = _regions.next();
126 while (r != NULL) {
127 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
128 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
129 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
130
131 if (r->is_committed()) {
132 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
133 }
134
135 r = _regions.next();
136 }
137 }
138 };
139
140 jint ShenandoahHeap::initialize() {
141 //
142 // Figure out heap sizing
143 //
144
145 size_t init_byte_size = InitialHeapSize;
146 size_t min_byte_size = MinHeapSize;
147 size_t max_byte_size = MaxHeapSize;
148 size_t heap_alignment = HeapAlignment;
149
150 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
151
152 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
153 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
154
155 _num_regions = ShenandoahHeapRegion::region_count();
156 assert(_num_regions == (max_byte_size / reg_size_bytes),
157 "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT,
158 _num_regions, max_byte_size, reg_size_bytes);
159
160 // Now we know the number of regions, initialize the heuristics.
161 initialize_heuristics();
162
163 size_t num_committed_regions = init_byte_size / reg_size_bytes;
164 num_committed_regions = MIN2(num_committed_regions, _num_regions);
165 assert(num_committed_regions <= _num_regions, "sanity");
166 _initial_size = num_committed_regions * reg_size_bytes;
167
168 size_t num_min_regions = min_byte_size / reg_size_bytes;
169 num_min_regions = MIN2(num_min_regions, _num_regions);
170 assert(num_min_regions <= _num_regions, "sanity");
171 _minimum_size = num_min_regions * reg_size_bytes;
172
173 // Default to max heap size.
174 _soft_max_size = _num_regions * reg_size_bytes;
175
176 _committed = _initial_size;
177
178 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
179 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
180 size_t region_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
181
182 //
183 // Reserve and commit memory for heap
184 //
185
186 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
187 initialize_reserved_region(heap_rs);
188 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
189 _heap_region_special = heap_rs.special();
190
191 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
192 "Misaligned heap: " PTR_FORMAT, p2i(base()));
193
194 #if SHENANDOAH_OPTIMIZED_MARKTASK
195 // The optimized ShenandoahMarkTask takes some bits away from the full object bits.
196 // Fail if we ever attempt to address more than we can.
197 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) {
198 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
199 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
200 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
201 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable());
202 vm_exit_during_initialization("Fatal Error", buf);
203 }
204 #endif
205
206 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
207 if (!_heap_region_special) {
208 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
209 "Cannot commit heap memory");
210 }
211
212 //
213 // Reserve and commit memory for bitmap(s)
214 //
215
216 _bitmap_size = ShenandoahMarkBitMap::compute_size(heap_rs.size());
217 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
218
219 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor();
220
221 guarantee(bitmap_bytes_per_region != 0,
222 "Bitmap bytes per region should not be zero");
223 guarantee(is_power_of_2(bitmap_bytes_per_region),
224 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
225
226 if (bitmap_page_size > bitmap_bytes_per_region) {
227 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
228 _bitmap_bytes_per_slice = bitmap_page_size;
229 } else {
230 _bitmap_regions_per_slice = 1;
231 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
232 }
233
234 guarantee(_bitmap_regions_per_slice >= 1,
235 "Should have at least one region per slice: " SIZE_FORMAT,
236 _bitmap_regions_per_slice);
237
238 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
239 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
240 _bitmap_bytes_per_slice, bitmap_page_size);
241
242 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
243 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
244 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
245 _bitmap_region_special = bitmap.special();
246
247 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
248 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
249 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
250 if (!_bitmap_region_special) {
251 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
252 "Cannot commit bitmap memory");
253 }
254
255 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions, _max_workers);
256
257 if (ShenandoahVerify) {
258 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
259 if (!verify_bitmap.special()) {
260 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
261 "Cannot commit verification bitmap memory");
262 }
263 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
264 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
265 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
266 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
267 }
268
269 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
270 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
271 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
272 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
273 _aux_bitmap_region_special = aux_bitmap.special();
274 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
275
276 //
277 // Create regions and region sets
278 //
279 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
280 size_t region_storage_size = align_up(region_align * _num_regions, region_page_size);
281 region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity());
282
283 ReservedSpace region_storage(region_storage_size, region_page_size);
284 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
285 if (!region_storage.special()) {
286 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
287 "Cannot commit region memory");
288 }
289
290 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks.
291 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there.
292 // If not successful, bite a bullet and allocate at whatever address.
293 {
294 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
295 size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align);
296
297 uintptr_t min = round_up_power_of_2(cset_align);
298 uintptr_t max = (1u << 30u);
299
300 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
301 char* req_addr = (char*)addr;
302 assert(is_aligned(req_addr, cset_align), "Should be aligned");
303 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size(), req_addr);
304 if (cset_rs.is_reserved()) {
305 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr);
306 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
307 break;
308 }
309 }
310
311 if (_collection_set == NULL) {
312 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size());
313 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
314 }
315 }
316
317 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
318 _free_set = new ShenandoahFreeSet(this, _num_regions);
319
320 {
321 ShenandoahHeapLocker locker(lock());
322
323 for (size_t i = 0; i < _num_regions; i++) {
324 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
325 bool is_committed = i < num_committed_regions;
326 void* loc = region_storage.base() + i * region_align;
327
328 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
329 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
330
331 _marking_context->initialize_top_at_mark_start(r);
332 _regions[i] = r;
333 assert(!collection_set()->is_in(i), "New region should not be in collection set");
334 }
335
336 // Initialize to complete
337 _marking_context->mark_complete();
338
339 _free_set->rebuild();
340 }
341
342 if (AlwaysPreTouch) {
343 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
344 // before initialize() below zeroes it with initializing thread. For any given region,
345 // we touch the region and the corresponding bitmaps from the same thread.
346 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
347
348 _pretouch_heap_page_size = heap_page_size;
349 _pretouch_bitmap_page_size = bitmap_page_size;
350
351 #ifdef LINUX
352 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
353 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
354 // them into huge one. Therefore, we need to pretouch with smaller pages.
355 if (UseTransparentHugePages) {
356 _pretouch_heap_page_size = (size_t)os::vm_page_size();
357 _pretouch_bitmap_page_size = (size_t)os::vm_page_size();
358 }
359 #endif
360
361 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
362 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
363
364 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size);
365 _workers->run_task(&bcl);
366
367 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size);
368 _workers->run_task(&hcl);
369 }
370
371 //
372 // Initialize the rest of GC subsystems
373 //
374
375 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
376 for (uint worker = 0; worker < _max_workers; worker++) {
377 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
378 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
379 }
380
381 // There should probably be Shenandoah-specific options for these,
382 // just as there are G1-specific options.
383 {
384 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
385 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
386 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
387 }
388
389 _monitoring_support = new ShenandoahMonitoringSupport(this);
390 _phase_timings = new ShenandoahPhaseTimings(max_workers());
391 ShenandoahCodeRoots::initialize();
392
393 if (ShenandoahPacing) {
394 _pacer = new ShenandoahPacer(this);
395 _pacer->setup_for_idle();
396 } else {
397 _pacer = NULL;
398 }
399
400 _control_thread = new ShenandoahControlThread();
401
402 ShenandoahInitLogger::print();
403
404 return JNI_OK;
405 }
406
407 void ShenandoahHeap::initialize_mode() {
408 if (ShenandoahGCMode != NULL) {
409 if (strcmp(ShenandoahGCMode, "satb") == 0) {
410 _gc_mode = new ShenandoahSATBMode();
411 } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
412 _gc_mode = new ShenandoahIUMode();
413 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
414 _gc_mode = new ShenandoahPassiveMode();
415 } else {
416 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
417 }
418 } else {
419 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)");
420 }
421 _gc_mode->initialize_flags();
422 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
423 vm_exit_during_initialization(
424 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
425 _gc_mode->name()));
426 }
427 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
428 vm_exit_during_initialization(
429 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
430 _gc_mode->name()));
431 }
432 }
433
434 void ShenandoahHeap::initialize_heuristics() {
435 assert(_gc_mode != NULL, "Must be initialized");
436 _heuristics = _gc_mode->initialize_heuristics();
437
438 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
439 vm_exit_during_initialization(
440 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
441 _heuristics->name()));
442 }
443 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
444 vm_exit_during_initialization(
445 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
446 _heuristics->name()));
447 }
448 }
449
450 #ifdef _MSC_VER
451 #pragma warning( push )
452 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
453 #endif
454
455 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
456 CollectedHeap(),
457 _initial_size(0),
458 _used(0),
459 _committed(0),
460 _bytes_allocated_since_gc_start(0),
461 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
462 _workers(NULL),
463 _safepoint_workers(NULL),
464 _heap_region_special(false),
465 _num_regions(0),
466 _regions(NULL),
467 _update_refs_iterator(this),
468 _control_thread(NULL),
469 _shenandoah_policy(policy),
470 _gc_mode(NULL),
471 _heuristics(NULL),
472 _free_set(NULL),
473 _pacer(NULL),
474 _verifier(NULL),
475 _phase_timings(NULL),
476 _monitoring_support(NULL),
477 _memory_pool(NULL),
478 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
479 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
480 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
481 _soft_ref_policy(),
482 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
483 _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))),
484 _marking_context(NULL),
485 _bitmap_size(0),
486 _bitmap_regions_per_slice(0),
487 _bitmap_bytes_per_slice(0),
488 _bitmap_region_special(false),
489 _aux_bitmap_region_special(false),
490 _liveness_cache(NULL),
491 _collection_set(NULL)
492 {
493 // Initialize GC mode early, so we can adjust barrier support
494 initialize_mode();
495 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
496
497 _max_workers = MAX2(_max_workers, 1U);
498 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
499 /* are_GC_task_threads */ true,
500 /* are_ConcurrentGC_threads */ true);
501 if (_workers == NULL) {
502 vm_exit_during_initialization("Failed necessary allocation.");
503 } else {
504 _workers->initialize_workers();
505 }
506
507 if (ParallelGCThreads > 1) {
508 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
509 ParallelGCThreads,
510 /* are_GC_task_threads */ false,
511 /* are_ConcurrentGC_threads */ false);
512 _safepoint_workers->initialize_workers();
513 }
514 }
515
516 #ifdef _MSC_VER
517 #pragma warning( pop )
518 #endif
519
520 class ShenandoahResetBitmapTask : public AbstractGangTask {
521 private:
522 ShenandoahRegionIterator _regions;
523
524 public:
525 ShenandoahResetBitmapTask() :
526 AbstractGangTask("Shenandoah Reset Bitmap") {}
527
528 void work(uint worker_id) {
529 ShenandoahHeapRegion* region = _regions.next();
530 ShenandoahHeap* heap = ShenandoahHeap::heap();
531 ShenandoahMarkingContext* const ctx = heap->marking_context();
532 while (region != NULL) {
533 if (heap->is_bitmap_slice_committed(region)) {
534 ctx->clear_bitmap(region);
535 }
536 region = _regions.next();
537 }
538 }
539 };
540
541 void ShenandoahHeap::reset_mark_bitmap() {
542 assert_gc_workers(_workers->active_workers());
543 mark_incomplete_marking_context();
544
545 ShenandoahResetBitmapTask task;
546 _workers->run_task(&task);
547 }
548
549 void ShenandoahHeap::print_on(outputStream* st) const {
550 st->print_cr("Shenandoah Heap");
551 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
552 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
553 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
554 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
555 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
556 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
557 num_regions(),
558 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
559 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
560
561 st->print("Status: ");
562 if (has_forwarded_objects()) st->print("has forwarded objects, ");
563 if (is_concurrent_mark_in_progress()) st->print("marking, ");
564 if (is_evacuation_in_progress()) st->print("evacuating, ");
565 if (is_update_refs_in_progress()) st->print("updating refs, ");
566 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
567 if (is_full_gc_in_progress()) st->print("full gc, ");
568 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
569 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
570 if (is_concurrent_strong_root_in_progress() &&
571 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
572
573 if (cancelled_gc()) {
574 st->print("cancelled");
575 } else {
576 st->print("not cancelled");
577 }
578 st->cr();
579
580 st->print_cr("Reserved region:");
581 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
582 p2i(reserved_region().start()),
583 p2i(reserved_region().end()));
584
585 ShenandoahCollectionSet* cset = collection_set();
586 st->print_cr("Collection set:");
587 if (cset != NULL) {
588 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
589 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
590 } else {
591 st->print_cr(" (NULL)");
592 }
593
594 st->cr();
595 MetaspaceUtils::print_on(st);
596
597 if (Verbose) {
598 print_heap_regions_on(st);
599 }
600 }
601
602 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
603 public:
604 void do_thread(Thread* thread) {
605 assert(thread != NULL, "Sanity");
606 assert(thread->is_Worker_thread(), "Only worker thread expected");
607 ShenandoahThreadLocalData::initialize_gclab(thread);
608 }
609 };
610
611 void ShenandoahHeap::post_initialize() {
612 CollectedHeap::post_initialize();
613 MutexLocker ml(Threads_lock);
614
615 ShenandoahInitWorkerGCLABClosure init_gclabs;
616 _workers->threads_do(&init_gclabs);
617
618 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
619 // Now, we will let WorkGang to initialize gclab when new worker is created.
620 _workers->set_initialize_gclab();
621 if (_safepoint_workers != NULL) {
622 _safepoint_workers->threads_do(&init_gclabs);
623 _safepoint_workers->set_initialize_gclab();
624 }
625
626 _heuristics->initialize();
627
628 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
629 }
630
631 size_t ShenandoahHeap::used() const {
632 return Atomic::load(&_used);
633 }
634
635 size_t ShenandoahHeap::committed() const {
636 return Atomic::load(&_committed);
637 }
638
639 void ShenandoahHeap::increase_committed(size_t bytes) {
640 shenandoah_assert_heaplocked_or_safepoint();
641 _committed += bytes;
642 }
643
644 void ShenandoahHeap::decrease_committed(size_t bytes) {
645 shenandoah_assert_heaplocked_or_safepoint();
646 _committed -= bytes;
647 }
648
649 void ShenandoahHeap::increase_used(size_t bytes) {
650 Atomic::add(&_used, bytes, memory_order_relaxed);
651 }
652
653 void ShenandoahHeap::set_used(size_t bytes) {
654 Atomic::store(&_used, bytes);
655 }
656
657 void ShenandoahHeap::decrease_used(size_t bytes) {
658 assert(used() >= bytes, "never decrease heap size by more than we've left");
659 Atomic::sub(&_used, bytes, memory_order_relaxed);
660 }
661
662 void ShenandoahHeap::increase_allocated(size_t bytes) {
663 Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed);
664 }
665
666 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
667 size_t bytes = words * HeapWordSize;
668 if (!waste) {
669 increase_used(bytes);
670 }
671 increase_allocated(bytes);
672 if (ShenandoahPacing) {
673 control_thread()->pacing_notify_alloc(words);
674 if (waste) {
675 pacer()->claim_for_alloc(words, true);
676 }
677 }
678 }
679
680 size_t ShenandoahHeap::capacity() const {
681 return committed();
682 }
683
684 size_t ShenandoahHeap::max_capacity() const {
685 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
686 }
687
688 size_t ShenandoahHeap::soft_max_capacity() const {
689 size_t v = Atomic::load(&_soft_max_size);
690 assert(min_capacity() <= v && v <= max_capacity(),
691 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
692 min_capacity(), v, max_capacity());
693 return v;
694 }
695
696 void ShenandoahHeap::set_soft_max_capacity(size_t v) {
697 assert(min_capacity() <= v && v <= max_capacity(),
698 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
699 min_capacity(), v, max_capacity());
700 Atomic::store(&_soft_max_size, v);
701 }
702
703 size_t ShenandoahHeap::min_capacity() const {
704 return _minimum_size;
705 }
706
707 size_t ShenandoahHeap::initial_capacity() const {
708 return _initial_size;
709 }
710
711 bool ShenandoahHeap::is_in(const void* p) const {
712 HeapWord* heap_base = (HeapWord*) base();
713 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
714 return p >= heap_base && p < last_region_end;
715 }
716
717 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
718 assert (ShenandoahUncommit, "should be enabled");
719
720 // Application allocates from the beginning of the heap, and GC allocates at
721 // the end of it. It is more efficient to uncommit from the end, so that applications
722 // could enjoy the near committed regions. GC allocations are much less frequent,
723 // and therefore can accept the committing costs.
724
725 size_t count = 0;
726 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
727 ShenandoahHeapRegion* r = get_region(i - 1);
728 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
729 ShenandoahHeapLocker locker(lock());
730 if (r->is_empty_committed()) {
731 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
732 break;
733 }
734
735 r->make_uncommitted();
736 count++;
737 }
738 }
739 SpinPause(); // allow allocators to take the lock
740 }
741
742 if (count > 0) {
743 control_thread()->notify_heap_changed();
744 }
745 }
746
747 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
748 // New object should fit the GCLAB size
749 size_t min_size = MAX2(size, PLAB::min_size());
750
751 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
752 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
753 new_size = MIN2(new_size, PLAB::max_size());
754 new_size = MAX2(new_size, PLAB::min_size());
755
756 // Record new heuristic value even if we take any shortcut. This captures
757 // the case when moderately-sized objects always take a shortcut. At some point,
758 // heuristics should catch up with them.
759 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
760
761 if (new_size < size) {
762 // New size still does not fit the object. Fall back to shared allocation.
763 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
764 return NULL;
765 }
766
767 // Retire current GCLAB, and allocate a new one.
768 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
769 gclab->retire();
770
771 size_t actual_size = 0;
772 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
773 if (gclab_buf == NULL) {
774 return NULL;
775 }
776
777 assert (size <= actual_size, "allocation should fit");
778
779 if (ZeroTLAB) {
780 // ..and clear it.
781 Copy::zero_to_words(gclab_buf, actual_size);
782 } else {
783 // ...and zap just allocated object.
784 #ifdef ASSERT
785 // Skip mangling the space corresponding to the object header to
786 // ensure that the returned space is not considered parsable by
787 // any concurrent GC thread.
788 size_t hdr_size = oopDesc::header_size();
789 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
790 #endif // ASSERT
791 }
792 gclab->set_buf(gclab_buf, actual_size);
793 return gclab->allocate(size);
794 }
795
796 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
797 size_t requested_size,
798 size_t* actual_size) {
799 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
800 HeapWord* res = allocate_memory(req);
801 if (res != NULL) {
802 *actual_size = req.actual_size();
803 } else {
804 *actual_size = 0;
805 }
806 return res;
807 }
808
809 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
810 size_t word_size,
811 size_t* actual_size) {
812 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
813 HeapWord* res = allocate_memory(req);
814 if (res != NULL) {
815 *actual_size = req.actual_size();
816 } else {
817 *actual_size = 0;
818 }
819 return res;
820 }
821
822 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
823 intptr_t pacer_epoch = 0;
824 bool in_new_region = false;
825 HeapWord* result = NULL;
826
827 if (req.is_mutator_alloc()) {
828 if (ShenandoahPacing) {
829 pacer()->pace_for_alloc(req.size());
830 pacer_epoch = pacer()->epoch();
831 }
832
833 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
834 result = allocate_memory_under_lock(req, in_new_region);
835 }
836
837 // Allocation failed, block until control thread reacted, then retry allocation.
838 //
839 // It might happen that one of the threads requesting allocation would unblock
840 // way later after GC happened, only to fail the second allocation, because
841 // other threads have already depleted the free storage. In this case, a better
842 // strategy is to try again, as long as GC makes progress.
843 //
844 // Then, we need to make sure the allocation was retried after at least one
845 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
846
847 size_t tries = 0;
848
849 while (result == NULL && _progress_last_gc.is_set()) {
850 tries++;
851 control_thread()->handle_alloc_failure(req);
852 result = allocate_memory_under_lock(req, in_new_region);
853 }
854
855 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
856 tries++;
857 control_thread()->handle_alloc_failure(req);
858 result = allocate_memory_under_lock(req, in_new_region);
859 }
860
861 } else {
862 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
863 result = allocate_memory_under_lock(req, in_new_region);
864 // Do not call handle_alloc_failure() here, because we cannot block.
865 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
866 }
867
868 if (in_new_region) {
869 control_thread()->notify_heap_changed();
870 }
871
872 if (result != NULL) {
873 size_t requested = req.size();
874 size_t actual = req.actual_size();
875
876 assert (req.is_lab_alloc() || (requested == actual),
877 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
878 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
879
880 if (req.is_mutator_alloc()) {
881 notify_mutator_alloc_words(actual, false);
882
883 // If we requested more than we were granted, give the rest back to pacer.
884 // This only matters if we are in the same pacing epoch: do not try to unpace
885 // over the budget for the other phase.
886 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
887 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
888 }
889 } else {
890 increase_used(actual*HeapWordSize);
891 }
892 }
893
894 return result;
895 }
896
897 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
898 ShenandoahHeapLocker locker(lock());
899 return _free_set->allocate(req, in_new_region);
900 }
901
902 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
903 bool* gc_overhead_limit_was_exceeded) {
904 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
905 return allocate_memory(req);
906 }
907
908 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
909 size_t size,
910 Metaspace::MetadataType mdtype) {
911 MetaWord* result;
912
913 // Inform metaspace OOM to GC heuristics if class unloading is possible.
914 if (heuristics()->can_unload_classes()) {
915 ShenandoahHeuristics* h = heuristics();
916 h->record_metaspace_oom();
917 }
918
919 // Expand and retry allocation
920 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
921 if (result != NULL) {
922 return result;
923 }
924
925 // Start full GC
926 collect(GCCause::_metadata_GC_clear_soft_refs);
927
928 // Retry allocation
929 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
930 if (result != NULL) {
931 return result;
932 }
933
934 // Expand and retry allocation
935 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
936 if (result != NULL) {
937 return result;
938 }
939
940 // Out of memory
941 return NULL;
942 }
943
944 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
945 private:
946 ShenandoahHeap* const _heap;
947 Thread* const _thread;
948 public:
949 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
950 _heap(heap), _thread(Thread::current()) {}
951
952 void do_object(oop p) {
953 shenandoah_assert_marked(NULL, p);
954 if (!p->is_forwarded()) {
955 _heap->evacuate_object(p, _thread);
956 }
957 }
958 };
959
960 class ShenandoahEvacuationTask : public AbstractGangTask {
961 private:
962 ShenandoahHeap* const _sh;
963 ShenandoahCollectionSet* const _cs;
964 bool _concurrent;
965 public:
966 ShenandoahEvacuationTask(ShenandoahHeap* sh,
967 ShenandoahCollectionSet* cs,
968 bool concurrent) :
969 AbstractGangTask("Shenandoah Evacuation"),
970 _sh(sh),
971 _cs(cs),
972 _concurrent(concurrent)
973 {}
974
975 void work(uint worker_id) {
976 if (_concurrent) {
977 ShenandoahConcurrentWorkerSession worker_session(worker_id);
978 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
979 ShenandoahEvacOOMScope oom_evac_scope;
980 do_work();
981 } else {
982 ShenandoahParallelWorkerSession worker_session(worker_id);
983 ShenandoahEvacOOMScope oom_evac_scope;
984 do_work();
985 }
986 }
987
988 private:
989 void do_work() {
990 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
991 ShenandoahHeapRegion* r;
992 while ((r =_cs->claim_next()) != NULL) {
993 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
994 _sh->marked_object_iterate(r, &cl);
995
996 if (ShenandoahPacing) {
997 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
998 }
999
1000 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1001 break;
1002 }
1003 }
1004 }
1005 };
1006
1007 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
1008 ShenandoahEvacuationTask task(this, _collection_set, concurrent);
1009 workers()->run_task(&task);
1010 }
1011
1012 void ShenandoahHeap::trash_cset_regions() {
1013 ShenandoahHeapLocker locker(lock());
1014
1015 ShenandoahCollectionSet* set = collection_set();
1016 ShenandoahHeapRegion* r;
1017 set->clear_current_index();
1018 while ((r = set->next()) != NULL) {
1019 r->make_trash();
1020 }
1021 collection_set()->clear();
1022 }
1023
1024 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1025 st->print_cr("Heap Regions:");
1026 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
1027 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
1028 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark");
1029 st->print_cr("SN=alloc sequence number");
1030
1031 for (size_t i = 0; i < num_regions(); i++) {
1032 get_region(i)->print_on(st);
1033 }
1034 }
1035
1036 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1037 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1038
1039 oop humongous_obj = cast_to_oop(start->bottom());
1040 size_t size = humongous_obj->size();
1041 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1042 size_t index = start->index() + required_regions - 1;
1043
1044 assert(!start->has_live(), "liveness must be zero");
1045
1046 for(size_t i = 0; i < required_regions; i++) {
1047 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1048 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1049 ShenandoahHeapRegion* region = get_region(index --);
1050
1051 assert(region->is_humongous(), "expect correct humongous start or continuation");
1052 assert(!region->is_cset(), "Humongous region should not be in collection set");
1053
1054 region->make_trash_immediate();
1055 }
1056 }
1057
1058 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1059 public:
1060 ShenandoahCheckCleanGCLABClosure() {}
1061 void do_thread(Thread* thread) {
1062 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1063 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1064 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1065 }
1066 };
1067
1068 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1069 private:
1070 bool const _resize;
1071 public:
1072 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1073 void do_thread(Thread* thread) {
1074 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1075 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1076 gclab->retire();
1077 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1078 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1079 }
1080 }
1081 };
1082
1083 void ShenandoahHeap::labs_make_parsable() {
1084 assert(UseTLAB, "Only call with UseTLAB");
1085
1086 ShenandoahRetireGCLABClosure cl(false);
1087
1088 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1089 ThreadLocalAllocBuffer& tlab = t->tlab();
1090 tlab.make_parsable();
1091 cl.do_thread(t);
1092 }
1093
1094 workers()->threads_do(&cl);
1095 }
1096
1097 void ShenandoahHeap::tlabs_retire(bool resize) {
1098 assert(UseTLAB, "Only call with UseTLAB");
1099 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1100
1101 ThreadLocalAllocStats stats;
1102
1103 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1104 ThreadLocalAllocBuffer& tlab = t->tlab();
1105 tlab.retire(&stats);
1106 if (resize) {
1107 tlab.resize();
1108 }
1109 }
1110
1111 stats.publish();
1112
1113 #ifdef ASSERT
1114 ShenandoahCheckCleanGCLABClosure cl;
1115 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1116 cl.do_thread(t);
1117 }
1118 workers()->threads_do(&cl);
1119 #endif
1120 }
1121
1122 void ShenandoahHeap::gclabs_retire(bool resize) {
1123 assert(UseTLAB, "Only call with UseTLAB");
1124 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1125
1126 ShenandoahRetireGCLABClosure cl(resize);
1127 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1128 cl.do_thread(t);
1129 }
1130 workers()->threads_do(&cl);
1131
1132 if (safepoint_workers() != NULL) {
1133 safepoint_workers()->threads_do(&cl);
1134 }
1135 }
1136
1137 // Returns size in bytes
1138 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1139 if (ShenandoahElasticTLAB) {
1140 // With Elastic TLABs, return the max allowed size, and let the allocation path
1141 // figure out the safe size for current allocation.
1142 return ShenandoahHeapRegion::max_tlab_size_bytes();
1143 } else {
1144 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1145 }
1146 }
1147
1148 size_t ShenandoahHeap::max_tlab_size() const {
1149 // Returns size in words
1150 return ShenandoahHeapRegion::max_tlab_size_words();
1151 }
1152
1153 void ShenandoahHeap::collect(GCCause::Cause cause) {
1154 control_thread()->request_gc(cause);
1155 }
1156
1157 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1158 //assert(false, "Shouldn't need to do full collections");
1159 }
1160
1161 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1162 ShenandoahHeapRegion* r = heap_region_containing(addr);
1163 if (r != NULL) {
1164 return r->block_start(addr);
1165 }
1166 return NULL;
1167 }
1168
1169 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1170 ShenandoahHeapRegion* r = heap_region_containing(addr);
1171 return r->block_is_obj(addr);
1172 }
1173
1174 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1175 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1176 }
1177
1178 void ShenandoahHeap::prepare_for_verify() {
1179 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1180 labs_make_parsable();
1181 }
1182 }
1183
1184 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1185 workers()->threads_do(tcl);
1186 if (_safepoint_workers != NULL) {
1187 _safepoint_workers->threads_do(tcl);
1188 }
1189 if (ShenandoahStringDedup::is_enabled()) {
1190 ShenandoahStringDedup::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::resolve_forwarded_not_null(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 ShenandoahHeapIterationRootScanner rp;
1325 rp.roots_do(oops);
1326 }
1327
1328 void ShenandoahHeap::reclaim_aux_bitmap_for_iteration() {
1329 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1330 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1331 }
1332 }
1333
1334 // Closure for parallelly iterate objects
1335 class ShenandoahObjectIterateParScanClosure : public BasicOopIterateClosure {
1336 private:
1337 MarkBitMap* _bitmap;
1338 ShenandoahObjToScanQueue* _queue;
1339 ShenandoahHeap* const _heap;
1340 ShenandoahMarkingContext* const _marking_context;
1341
1342 template <class T>
1343 void do_oop_work(T* p) {
1344 T o = RawAccess<>::oop_load(p);
1345 if (!CompressedOops::is_null(o)) {
1346 oop obj = CompressedOops::decode_not_null(o);
1347 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1348 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1349 return;
1350 }
1351 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1352
1353 assert(oopDesc::is_oop(obj), "Must be a valid oop");
1354 if (_bitmap->par_mark(obj)) {
1355 _queue->push(ShenandoahMarkTask(obj));
1356 }
1357 }
1358 }
1359 public:
1360 ShenandoahObjectIterateParScanClosure(MarkBitMap* bitmap, ShenandoahObjToScanQueue* q) :
1361 _bitmap(bitmap), _queue(q), _heap(ShenandoahHeap::heap()),
1362 _marking_context(_heap->marking_context()) {}
1363 void do_oop(oop* p) { do_oop_work(p); }
1364 void do_oop(narrowOop* p) { do_oop_work(p); }
1365 };
1366
1367 // Object iterator for parallel heap iteraion.
1368 // The root scanning phase happenes in construction as a preparation of
1369 // parallel marking queues.
1370 // Every worker processes it's own marking queue. work-stealing is used
1371 // to balance workload.
1372 class ShenandoahParallelObjectIterator : public ParallelObjectIterator {
1373 private:
1374 uint _num_workers;
1375 bool _init_ready;
1376 MarkBitMap* _aux_bit_map;
1377 ShenandoahHeap* _heap;
1378 ShenandoahScanObjectStack _roots_stack; // global roots stack
1379 ShenandoahObjToScanQueueSet* _task_queues;
1380 public:
1381 ShenandoahParallelObjectIterator(uint num_workers, MarkBitMap* bitmap) :
1382 _num_workers(num_workers),
1383 _init_ready(false),
1384 _aux_bit_map(bitmap),
1385 _heap(ShenandoahHeap::heap()) {
1386 // Initialize bitmap
1387 _init_ready = _heap->prepare_aux_bitmap_for_iteration();
1388 if (!_init_ready) {
1389 return;
1390 }
1391
1392 ObjectIterateScanRootClosure oops(_aux_bit_map, &_roots_stack);
1393 _heap->scan_roots_for_iteration(&_roots_stack, &oops);
1394
1395 _init_ready = prepare_worker_queues();
1396 }
1397
1398 ~ShenandoahParallelObjectIterator() {
1399 // Reclaim bitmap
1400 _heap->reclaim_aux_bitmap_for_iteration();
1401 // Reclaim queue for workers
1402 if (_task_queues!= NULL) {
1403 for (uint i = 0; i < _num_workers; ++i) {
1404 ShenandoahObjToScanQueue* q = _task_queues->queue(i);
1405 if (q != NULL) {
1406 delete q;
1407 _task_queues->register_queue(i, NULL);
1408 }
1409 }
1410 delete _task_queues;
1411 _task_queues = NULL;
1412 }
1413 }
1414
1415 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
1416 if (_init_ready) {
1417 object_iterate_parallel(cl, worker_id, _task_queues);
1418 }
1419 }
1420
1421 private:
1422 // Divide global root_stack into worker queues
1423 bool prepare_worker_queues() {
1424 _task_queues = new ShenandoahObjToScanQueueSet((int) _num_workers);
1425 // Initialize queues for every workers
1426 for (uint i = 0; i < _num_workers; ++i) {
1427 ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue();
1428 task_queue->initialize();
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 != NULL, "task queue must not be NULL");
1453
1454 ShenandoahObjToScanQueue* q = queue_set->queue(worker_id);
1455 assert(q != NULL, "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 ParallelObjectIterator* 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 != NULL)) {
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 AbstractGangTask {
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 AbstractGangTask("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_and_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 ShenandoahGCPhase gc_phase(phase);
1785 ShenandoahGCWorkerPhase worker_phase(phase);
1786 bool purged_class = SystemDictionary::do_unloading(gc_timer());
1787
1788 ShenandoahIsAliveSelector is_alive;
1789 uint num_workers = _workers->active_workers();
1790 ShenandoahClassUnloadingTask unlink_task(phase, is_alive.is_alive_closure(), num_workers, purged_class);
1791 _workers->run_task(&unlink_task);
1792 }
1793
1794 {
1795 ShenandoahGCPhase phase(full_gc ?
1796 ShenandoahPhaseTimings::full_gc_purge_cldg :
1797 ShenandoahPhaseTimings::degen_gc_purge_cldg);
1798 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
1799 }
1800 // Resize and verify metaspace
1801 MetaspaceGC::compute_new_size();
1802 DEBUG_ONLY(MetaspaceUtils::verify();)
1803 }
1804
1805 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
1806 // so they should not have forwarded oops.
1807 // However, we do need to "null" dead oops in the roots, if can not be done
1808 // in concurrent cycles.
1809 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
1810 uint num_workers = _workers->active_workers();
1811 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
1812 ShenandoahPhaseTimings::full_gc_purge_weak_par :
1813 ShenandoahPhaseTimings::degen_gc_purge_weak_par;
1814 ShenandoahGCPhase phase(timing_phase);
1815 ShenandoahGCWorkerPhase worker_phase(timing_phase);
1816 // Cleanup weak roots
1817 if (has_forwarded_objects()) {
1818 ShenandoahForwardedIsAliveClosure is_alive;
1819 ShenandoahUpdateRefsClosure keep_alive;
1820 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
1821 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers);
1822 _workers->run_task(&cleaning_task);
1823 } else {
1824 ShenandoahIsAliveClosure is_alive;
1825 #ifdef ASSERT
1826 ShenandoahAssertNotForwardedClosure verify_cl;
1827 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
1828 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers);
1829 #else
1830 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
1831 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers);
1832 #endif
1833 _workers->run_task(&cleaning_task);
1834 }
1835 }
1836
1837 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
1838 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1839 assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC");
1840 ShenandoahGCPhase phase(full_gc ?
1841 ShenandoahPhaseTimings::full_gc_purge :
1842 ShenandoahPhaseTimings::degen_gc_purge);
1843 stw_weak_refs(full_gc);
1844 stw_process_weak_roots(full_gc);
1845 stw_unload_classes(full_gc);
1846 }
1847
1848 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
1849 set_gc_state_mask(HAS_FORWARDED, cond);
1850 }
1851
1852 void ShenandoahHeap::set_unload_classes(bool uc) {
1853 _unload_classes.set_cond(uc);
1854 }
1855
1856 bool ShenandoahHeap::unload_classes() const {
1857 return _unload_classes.is_set();
1858 }
1859
1860 address ShenandoahHeap::in_cset_fast_test_addr() {
1861 ShenandoahHeap* heap = ShenandoahHeap::heap();
1862 assert(heap->collection_set() != NULL, "Sanity");
1863 return (address) heap->collection_set()->biased_map_address();
1864 }
1865
1866 address ShenandoahHeap::cancelled_gc_addr() {
1867 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
1868 }
1869
1870 address ShenandoahHeap::gc_state_addr() {
1871 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
1872 }
1873
1874 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
1875 return Atomic::load(&_bytes_allocated_since_gc_start);
1876 }
1877
1878 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
1879 Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0);
1880 }
1881
1882 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
1883 _degenerated_gc_in_progress.set_cond(in_progress);
1884 }
1885
1886 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
1887 _full_gc_in_progress.set_cond(in_progress);
1888 }
1889
1890 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
1891 assert (is_full_gc_in_progress(), "should be");
1892 _full_gc_move_in_progress.set_cond(in_progress);
1893 }
1894
1895 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
1896 set_gc_state_mask(UPDATEREFS, in_progress);
1897 }
1898
1899 void ShenandoahHeap::register_nmethod(nmethod* nm) {
1900 ShenandoahCodeRoots::register_nmethod(nm);
1901 }
1902
1903 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
1904 ShenandoahCodeRoots::unregister_nmethod(nm);
1905 }
1906
1907 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
1908 ShenandoahCodeRoots::flush_nmethod(nm);
1909 }
1910
1911 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
1912 heap_region_containing(o)->record_pin();
1913 return o;
1914 }
1915
1916 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
1917 ShenandoahHeapRegion* r = heap_region_containing(o);
1918 assert(r != NULL, "Sanity");
1919 assert(r->pin_count() > 0, "Region " SIZE_FORMAT " should have non-zero pins", r->index());
1920 r->record_unpin();
1921 }
1922
1923 void ShenandoahHeap::sync_pinned_region_status() {
1924 ShenandoahHeapLocker locker(lock());
1925
1926 for (size_t i = 0; i < num_regions(); i++) {
1927 ShenandoahHeapRegion *r = get_region(i);
1928 if (r->is_active()) {
1929 if (r->is_pinned()) {
1930 if (r->pin_count() == 0) {
1931 r->make_unpinned();
1932 }
1933 } else {
1934 if (r->pin_count() > 0) {
1935 r->make_pinned();
1936 }
1937 }
1938 }
1939 }
1940
1941 assert_pinned_region_status();
1942 }
1943
1944 #ifdef ASSERT
1945 void ShenandoahHeap::assert_pinned_region_status() {
1946 for (size_t i = 0; i < num_regions(); i++) {
1947 ShenandoahHeapRegion* r = get_region(i);
1948 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
1949 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
1950 }
1951 }
1952 #endif
1953
1954 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
1955 return _gc_timer;
1956 }
1957
1958 void ShenandoahHeap::prepare_concurrent_roots() {
1959 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1960 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1961 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
1962 set_concurrent_weak_root_in_progress(true);
1963 if (unload_classes()) {
1964 _unloader.prepare();
1965 }
1966 }
1967
1968 void ShenandoahHeap::finish_concurrent_roots() {
1969 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1970 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1971 if (unload_classes()) {
1972 _unloader.finish();
1973 }
1974 }
1975
1976 #ifdef ASSERT
1977 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
1978 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
1979
1980 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1981 if (UseDynamicNumberOfGCThreads) {
1982 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
1983 } else {
1984 // Use ParallelGCThreads inside safepoints
1985 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
1986 }
1987 } else {
1988 if (UseDynamicNumberOfGCThreads) {
1989 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
1990 } else {
1991 // Use ConcGCThreads outside safepoints
1992 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
1993 }
1994 }
1995 }
1996 #endif
1997
1998 ShenandoahVerifier* ShenandoahHeap::verifier() {
1999 guarantee(ShenandoahVerify, "Should be enabled");
2000 assert (_verifier != NULL, "sanity");
2001 return _verifier;
2002 }
2003
2004 template<bool CONCURRENT>
2005 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2006 private:
2007 ShenandoahHeap* _heap;
2008 ShenandoahRegionIterator* _regions;
2009 public:
2010 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
2011 AbstractGangTask("Shenandoah Update References"),
2012 _heap(ShenandoahHeap::heap()),
2013 _regions(regions) {
2014 }
2015
2016 void work(uint worker_id) {
2017 if (CONCURRENT) {
2018 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2019 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2020 do_work<ShenandoahConcUpdateRefsClosure>();
2021 } else {
2022 ShenandoahParallelWorkerSession worker_session(worker_id);
2023 do_work<ShenandoahSTWUpdateRefsClosure>();
2024 }
2025 }
2026
2027 private:
2028 template<class T>
2029 void do_work() {
2030 T cl;
2031 ShenandoahHeapRegion* r = _regions->next();
2032 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2033 while (r != NULL) {
2034 HeapWord* update_watermark = r->get_update_watermark();
2035 assert (update_watermark >= r->bottom(), "sanity");
2036 if (r->is_active() && !r->is_cset()) {
2037 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2038 }
2039 if (ShenandoahPacing) {
2040 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2041 }
2042 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2043 return;
2044 }
2045 r = _regions->next();
2046 }
2047 }
2048 };
2049
2050 void ShenandoahHeap::update_heap_references(bool concurrent) {
2051 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2052
2053 if (concurrent) {
2054 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator);
2055 workers()->run_task(&task);
2056 } else {
2057 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
2058 workers()->run_task(&task);
2059 }
2060 }
2061
2062
2063 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2064 private:
2065 ShenandoahHeapLock* const _lock;
2066
2067 public:
2068 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2069
2070 void heap_region_do(ShenandoahHeapRegion* r) {
2071 // Drop unnecessary "pinned" state from regions that does not have CP marks
2072 // anymore, as this would allow trashing them.
2073
2074 if (r->is_active()) {
2075 if (r->is_pinned()) {
2076 if (r->pin_count() == 0) {
2077 ShenandoahHeapLocker locker(_lock);
2078 r->make_unpinned();
2079 }
2080 } else {
2081 if (r->pin_count() > 0) {
2082 ShenandoahHeapLocker locker(_lock);
2083 r->make_pinned();
2084 }
2085 }
2086 }
2087 }
2088
2089 bool is_thread_safe() { return true; }
2090 };
2091
2092 void ShenandoahHeap::update_heap_region_states(bool concurrent) {
2093 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2094 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2095
2096 {
2097 ShenandoahGCPhase phase(concurrent ?
2098 ShenandoahPhaseTimings::final_update_refs_update_region_states :
2099 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states);
2100 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2101 parallel_heap_region_iterate(&cl);
2102
2103 assert_pinned_region_status();
2104 }
2105
2106 {
2107 ShenandoahGCPhase phase(concurrent ?
2108 ShenandoahPhaseTimings::final_update_refs_trash_cset :
2109 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset);
2110 trash_cset_regions();
2111 }
2112 }
2113
2114 void ShenandoahHeap::rebuild_free_set(bool concurrent) {
2115 {
2116 ShenandoahGCPhase phase(concurrent ?
2117 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
2118 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
2119 ShenandoahHeapLocker locker(lock());
2120 _free_set->rebuild();
2121 }
2122 }
2123
2124 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2125 print_on(st);
2126 print_heap_regions_on(st);
2127 }
2128
2129 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2130 size_t slice = r->index() / _bitmap_regions_per_slice;
2131
2132 size_t regions_from = _bitmap_regions_per_slice * slice;
2133 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2134 for (size_t g = regions_from; g < regions_to; g++) {
2135 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2136 if (skip_self && g == r->index()) continue;
2137 if (get_region(g)->is_committed()) {
2138 return true;
2139 }
2140 }
2141 return false;
2142 }
2143
2144 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2145 shenandoah_assert_heaplocked();
2146
2147 // Bitmaps in special regions do not need commits
2148 if (_bitmap_region_special) {
2149 return true;
2150 }
2151
2152 if (is_bitmap_slice_committed(r, true)) {
2153 // Some other region from the group is already committed, meaning the bitmap
2154 // slice is already committed, we exit right away.
2155 return true;
2156 }
2157
2158 // Commit the bitmap slice:
2159 size_t slice = r->index() / _bitmap_regions_per_slice;
2160 size_t off = _bitmap_bytes_per_slice * slice;
2161 size_t len = _bitmap_bytes_per_slice;
2162 char* start = (char*) _bitmap_region.start() + off;
2163
2164 if (!os::commit_memory(start, len, false)) {
2165 return false;
2166 }
2167
2168 if (AlwaysPreTouch) {
2169 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size);
2170 }
2171
2172 return true;
2173 }
2174
2175 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2176 shenandoah_assert_heaplocked();
2177
2178 // Bitmaps in special regions do not need uncommits
2179 if (_bitmap_region_special) {
2180 return true;
2181 }
2182
2183 if (is_bitmap_slice_committed(r, true)) {
2184 // Some other region from the group is still committed, meaning the bitmap
2185 // slice is should stay committed, exit right away.
2186 return true;
2187 }
2188
2189 // Uncommit the bitmap slice:
2190 size_t slice = r->index() / _bitmap_regions_per_slice;
2191 size_t off = _bitmap_bytes_per_slice * slice;
2192 size_t len = _bitmap_bytes_per_slice;
2193 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2194 return false;
2195 }
2196 return true;
2197 }
2198
2199 void ShenandoahHeap::safepoint_synchronize_begin() {
2200 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2201 SuspendibleThreadSet::synchronize();
2202 }
2203 }
2204
2205 void ShenandoahHeap::safepoint_synchronize_end() {
2206 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2207 SuspendibleThreadSet::desynchronize();
2208 }
2209 }
2210
2211 void ShenandoahHeap::entry_uncommit(double shrink_before, size_t shrink_until) {
2212 static const char *msg = "Concurrent uncommit";
2213 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
2214 EventMark em("%s", msg);
2215
2216 op_uncommit(shrink_before, shrink_until);
2217 }
2218
2219 void ShenandoahHeap::try_inject_alloc_failure() {
2220 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2221 _inject_alloc_failure.set();
2222 os::naked_short_sleep(1);
2223 if (cancelled_gc()) {
2224 log_info(gc)("Allocation failure was successfully injected");
2225 }
2226 }
2227 }
2228
2229 bool ShenandoahHeap::should_inject_alloc_failure() {
2230 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2231 }
2232
2233 void ShenandoahHeap::initialize_serviceability() {
2234 _memory_pool = new ShenandoahMemoryPool(this);
2235 _cycle_memory_manager.add_pool(_memory_pool);
2236 _stw_memory_manager.add_pool(_memory_pool);
2237 }
2238
2239 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2240 GrowableArray<GCMemoryManager*> memory_managers(2);
2241 memory_managers.append(&_cycle_memory_manager);
2242 memory_managers.append(&_stw_memory_manager);
2243 return memory_managers;
2244 }
2245
2246 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2247 GrowableArray<MemoryPool*> memory_pools(1);
2248 memory_pools.append(_memory_pool);
2249 return memory_pools;
2250 }
2251
2252 MemoryUsage ShenandoahHeap::memory_usage() {
2253 return _memory_pool->get_memory_usage();
2254 }
2255
2256 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2257 _heap(ShenandoahHeap::heap()),
2258 _index(0) {}
2259
2260 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2261 _heap(heap),
2262 _index(0) {}
2263
2264 void ShenandoahRegionIterator::reset() {
2265 _index = 0;
2266 }
2267
2268 bool ShenandoahRegionIterator::has_next() const {
2269 return _index < _heap->num_regions();
2270 }
2271
2272 char ShenandoahHeap::gc_state() const {
2273 return _gc_state.raw_value();
2274 }
2275
2276 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2277 #ifdef ASSERT
2278 assert(_liveness_cache != NULL, "sanity");
2279 assert(worker_id < _max_workers, "sanity");
2280 for (uint i = 0; i < num_regions(); i++) {
2281 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2282 }
2283 #endif
2284 return _liveness_cache[worker_id];
2285 }
2286
2287 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2288 assert(worker_id < _max_workers, "sanity");
2289 assert(_liveness_cache != NULL, "sanity");
2290 ShenandoahLiveData* ld = _liveness_cache[worker_id];
2291 for (uint i = 0; i < num_regions(); i++) {
2292 ShenandoahLiveData live = ld[i];
2293 if (live > 0) {
2294 ShenandoahHeapRegion* r = get_region(i);
2295 r->increase_live_data_gc_words(live);
2296 ld[i] = 0;
2297 }
2298 }
2299 }