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/slidingForwarding.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/shenandoahControlThread.hpp"
44 #include "gc/shenandoah/shenandoahFreeSet.hpp"
45 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
46 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
47 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
48 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
49 #include "gc/shenandoah/shenandoahInitLogger.hpp"
50 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
51 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
52 #include "gc/shenandoah/shenandoahMetrics.hpp"
53 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
54 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
55 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
56 #include "gc/shenandoah/shenandoahPadding.hpp"
57 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
58 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
59 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
60 #include "gc/shenandoah/shenandoahStringDedup.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 "memory/classLoaderMetaspace.hpp"
77 #include "memory/metaspaceUtils.hpp"
78 #include "oops/compressedOops.inline.hpp"
79 #include "prims/jvmtiTagMap.hpp"
80 #include "runtime/atomic.hpp"
81 #include "runtime/globals.hpp"
82 #include "runtime/interfaceSupport.inline.hpp"
83 #include "runtime/java.hpp"
84 #include "runtime/orderAccess.hpp"
85 #include "runtime/safepointMechanism.hpp"
86 #include "runtime/vmThread.hpp"
87 #include "services/mallocTracker.hpp"
88 #include "services/memTracker.hpp"
89 #include "utilities/events.hpp"
90 #include "utilities/powerOfTwo.hpp"
91
92 class ShenandoahPretouchHeapTask : public AbstractGangTask {
93 private:
94 ShenandoahRegionIterator _regions;
95 const size_t _page_size;
96 public:
97 ShenandoahPretouchHeapTask(size_t page_size) :
98 AbstractGangTask("Shenandoah Pretouch Heap"),
99 _page_size(page_size) {}
100
101 virtual void work(uint worker_id) {
102 ShenandoahHeapRegion* r = _regions.next();
103 while (r != NULL) {
104 if (r->is_committed()) {
105 os::pretouch_memory(r->bottom(), r->end(), _page_size);
106 }
107 r = _regions.next();
108 }
109 }
110 };
111
112 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
113 private:
114 ShenandoahRegionIterator _regions;
115 char* _bitmap_base;
116 const size_t _bitmap_size;
117 const size_t _page_size;
118 public:
119 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
120 AbstractGangTask("Shenandoah Pretouch Bitmap"),
121 _bitmap_base(bitmap_base),
122 _bitmap_size(bitmap_size),
123 _page_size(page_size) {}
124
125 virtual void work(uint worker_id) {
126 ShenandoahHeapRegion* r = _regions.next();
127 while (r != NULL) {
128 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
129 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
130 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
131
132 if (r->is_committed()) {
133 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
134 }
135
136 r = _regions.next();
137 }
138 }
139 };
140
141 jint ShenandoahHeap::initialize() {
142 //
143 // Figure out heap sizing
144 //
145
146 size_t init_byte_size = InitialHeapSize;
147 size_t min_byte_size = MinHeapSize;
148 size_t max_byte_size = MaxHeapSize;
149 size_t heap_alignment = HeapAlignment;
150
151 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
152
153 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
154 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
155
156 _num_regions = ShenandoahHeapRegion::region_count();
157 assert(_num_regions == (max_byte_size / reg_size_bytes),
158 "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT,
159 _num_regions, max_byte_size, reg_size_bytes);
160
161 // Now we know the number of regions, initialize the heuristics.
162 initialize_heuristics();
163
164 size_t num_committed_regions = init_byte_size / reg_size_bytes;
165 num_committed_regions = MIN2(num_committed_regions, _num_regions);
166 assert(num_committed_regions <= _num_regions, "sanity");
167 _initial_size = num_committed_regions * reg_size_bytes;
168
169 size_t num_min_regions = min_byte_size / reg_size_bytes;
170 num_min_regions = MIN2(num_min_regions, _num_regions);
171 assert(num_min_regions <= _num_regions, "sanity");
172 _minimum_size = num_min_regions * reg_size_bytes;
173
174 // Default to max heap size.
175 _soft_max_size = _num_regions * reg_size_bytes;
176
177 _committed = _initial_size;
178
179 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
180 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
181 size_t region_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
182
183 //
184 // Reserve and commit memory for heap
185 //
186
187 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
188 initialize_reserved_region(heap_rs);
189 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
190 _heap_region_special = heap_rs.special();
191
192 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
193 "Misaligned heap: " PTR_FORMAT, p2i(base()));
194
195 #if SHENANDOAH_OPTIMIZED_MARKTASK
196 // The optimized ShenandoahMarkTask takes some bits away from the full object bits.
197 // Fail if we ever attempt to address more than we can.
198 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) {
199 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
200 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
201 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
202 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable());
203 vm_exit_during_initialization("Fatal Error", buf);
204 }
205 #endif
206
207 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
208 if (!_heap_region_special) {
209 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
210 "Cannot commit heap memory");
211 }
212
213 //
214 // Reserve and commit memory for bitmap(s)
215 //
216
217 _bitmap_size = ShenandoahMarkBitMap::compute_size(heap_rs.size());
218 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
219
220 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor();
221
222 guarantee(bitmap_bytes_per_region != 0,
223 "Bitmap bytes per region should not be zero");
224 guarantee(is_power_of_2(bitmap_bytes_per_region),
225 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
226
227 if (bitmap_page_size > bitmap_bytes_per_region) {
228 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
229 _bitmap_bytes_per_slice = bitmap_page_size;
230 } else {
231 _bitmap_regions_per_slice = 1;
232 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
233 }
234
235 guarantee(_bitmap_regions_per_slice >= 1,
236 "Should have at least one region per slice: " SIZE_FORMAT,
237 _bitmap_regions_per_slice);
238
239 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
240 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
241 _bitmap_bytes_per_slice, bitmap_page_size);
242
243 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
244 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
245 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
246 _bitmap_region_special = bitmap.special();
247
248 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
249 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
250 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
251 if (!_bitmap_region_special) {
252 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
253 "Cannot commit bitmap memory");
254 }
255
256 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions, _max_workers);
257
258 if (ShenandoahVerify) {
259 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
260 if (!verify_bitmap.special()) {
261 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
262 "Cannot commit verification bitmap memory");
263 }
264 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
265 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
266 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
267 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
268 }
269
270 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
271 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
272 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
273 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
274 _aux_bitmap_region_special = aux_bitmap.special();
275 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
276
277 //
278 // Create regions and region sets
279 //
280 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
281 size_t region_storage_size = align_up(region_align * _num_regions, region_page_size);
282 region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity());
283
284 ReservedSpace region_storage(region_storage_size, region_page_size);
285 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
286 if (!region_storage.special()) {
287 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
288 "Cannot commit region memory");
289 }
290
291 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks.
292 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there.
293 // If not successful, bite a bullet and allocate at whatever address.
294 {
295 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
296 size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align);
297
298 uintptr_t min = round_up_power_of_2(cset_align);
299 uintptr_t max = (1u << 30u);
300
301 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
302 char* req_addr = (char*)addr;
303 assert(is_aligned(req_addr, cset_align), "Should be aligned");
304 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size(), req_addr);
305 if (cset_rs.is_reserved()) {
306 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr);
307 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
308 break;
309 }
310 }
311
312 if (_collection_set == NULL) {
313 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size());
314 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
315 }
316 }
317
318 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
319 _free_set = new ShenandoahFreeSet(this, _num_regions);
320
321 {
322 ShenandoahHeapLocker locker(lock());
323
324 for (size_t i = 0; i < _num_regions; i++) {
325 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
326 bool is_committed = i < num_committed_regions;
327 void* loc = region_storage.base() + i * region_align;
328
329 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
330 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
331
332 _marking_context->initialize_top_at_mark_start(r);
333 _regions[i] = r;
334 assert(!collection_set()->is_in(i), "New region should not be in collection set");
335 }
336
337 // Initialize to complete
338 _marking_context->mark_complete();
339
340 _free_set->rebuild();
341 }
342
343 if (AlwaysPreTouch) {
344 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
345 // before initialize() below zeroes it with initializing thread. For any given region,
346 // we touch the region and the corresponding bitmaps from the same thread.
347 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
348
349 _pretouch_heap_page_size = heap_page_size;
350 _pretouch_bitmap_page_size = bitmap_page_size;
351
352 #ifdef LINUX
353 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
354 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
355 // them into huge one. Therefore, we need to pretouch with smaller pages.
356 if (UseTransparentHugePages) {
357 _pretouch_heap_page_size = (size_t)os::vm_page_size();
358 _pretouch_bitmap_page_size = (size_t)os::vm_page_size();
359 }
360 #endif
361
362 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
363 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
364
365 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size);
366 _workers->run_task(&bcl);
367
368 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size);
369 _workers->run_task(&hcl);
370 }
371
372 //
373 // Initialize the rest of GC subsystems
374 //
375
376 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
377 for (uint worker = 0; worker < _max_workers; worker++) {
378 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
379 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
380 }
381
382 // There should probably be Shenandoah-specific options for these,
383 // just as there are G1-specific options.
384 {
385 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
386 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
387 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
388 }
389
390 _monitoring_support = new ShenandoahMonitoringSupport(this);
391 _phase_timings = new ShenandoahPhaseTimings(max_workers());
392 ShenandoahCodeRoots::initialize();
393
394 if (ShenandoahPacing) {
395 _pacer = new ShenandoahPacer(this);
396 _pacer->setup_for_idle();
397 } else {
398 _pacer = NULL;
399 }
400
401 _control_thread = new ShenandoahControlThread();
402
403 ShenandoahInitLogger::print();
404
405 SlidingForwarding::initialize(_heap_region, ShenandoahHeapRegion::region_size_words());
406
407 return JNI_OK;
408 }
409
410 void ShenandoahHeap::initialize_mode() {
411 if (ShenandoahGCMode != NULL) {
412 if (strcmp(ShenandoahGCMode, "satb") == 0) {
413 _gc_mode = new ShenandoahSATBMode();
414 } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
415 _gc_mode = new ShenandoahIUMode();
416 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
417 _gc_mode = new ShenandoahPassiveMode();
418 } else {
419 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
420 }
421 } else {
422 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)");
423 }
424 _gc_mode->initialize_flags();
425 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
426 vm_exit_during_initialization(
427 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
428 _gc_mode->name()));
429 }
430 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
431 vm_exit_during_initialization(
432 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
433 _gc_mode->name()));
434 }
435 }
436
437 void ShenandoahHeap::initialize_heuristics() {
438 assert(_gc_mode != NULL, "Must be initialized");
439 _heuristics = _gc_mode->initialize_heuristics();
440
441 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
442 vm_exit_during_initialization(
443 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
444 _heuristics->name()));
445 }
446 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
447 vm_exit_during_initialization(
448 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
449 _heuristics->name()));
450 }
451 }
452
453 #ifdef _MSC_VER
454 #pragma warning( push )
455 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
456 #endif
457
458 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
459 CollectedHeap(),
460 _initial_size(0),
461 _used(0),
462 _committed(0),
463 _bytes_allocated_since_gc_start(0),
464 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
465 _workers(NULL),
466 _safepoint_workers(NULL),
467 _heap_region_special(false),
468 _num_regions(0),
469 _regions(NULL),
470 _update_refs_iterator(this),
471 _gc_state_changed(false),
472 _control_thread(NULL),
473 _shenandoah_policy(policy),
474 _gc_mode(NULL),
475 _heuristics(NULL),
476 _free_set(NULL),
477 _pacer(NULL),
478 _verifier(NULL),
479 _phase_timings(NULL),
480 _monitoring_support(NULL),
481 _memory_pool(NULL),
482 _stw_memory_manager("Shenandoah Pauses"),
483 _cycle_memory_manager("Shenandoah Cycles"),
484 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
485 _soft_ref_policy(),
486 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
487 _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))),
488 _marking_context(NULL),
489 _bitmap_size(0),
490 _bitmap_regions_per_slice(0),
491 _bitmap_bytes_per_slice(0),
492 _bitmap_region_special(false),
493 _aux_bitmap_region_special(false),
494 _liveness_cache(NULL),
495 _collection_set(NULL)
496 {
497 // Initialize GC mode early, so we can adjust barrier support
498 initialize_mode();
499 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
500
501 _max_workers = MAX2(_max_workers, 1U);
502 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
503 /* are_GC_task_threads */ true,
504 /* are_ConcurrentGC_threads */ true);
505 if (_workers == NULL) {
506 vm_exit_during_initialization("Failed necessary allocation.");
507 } else {
508 _workers->initialize_workers();
509 }
510
511 if (ParallelGCThreads > 1) {
512 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
513 ParallelGCThreads,
514 /* are_GC_task_threads */ false,
515 /* are_ConcurrentGC_threads */ false);
516 _safepoint_workers->initialize_workers();
517 }
518 }
519
520 #ifdef _MSC_VER
521 #pragma warning( pop )
522 #endif
523
524 class ShenandoahResetBitmapTask : public AbstractGangTask {
525 private:
526 ShenandoahRegionIterator _regions;
527
528 public:
529 ShenandoahResetBitmapTask() :
530 AbstractGangTask("Shenandoah Reset Bitmap") {}
531
532 void work(uint worker_id) {
533 ShenandoahHeapRegion* region = _regions.next();
534 ShenandoahHeap* heap = ShenandoahHeap::heap();
535 ShenandoahMarkingContext* const ctx = heap->marking_context();
536 while (region != NULL) {
537 if (heap->is_bitmap_slice_committed(region)) {
538 ctx->clear_bitmap(region);
539 }
540 region = _regions.next();
541 }
542 }
543 };
544
545 void ShenandoahHeap::reset_mark_bitmap() {
546 assert_gc_workers(_workers->active_workers());
547 mark_incomplete_marking_context();
548
549 ShenandoahResetBitmapTask task;
550 _workers->run_task(&task);
551 }
552
553 void ShenandoahHeap::print_on(outputStream* st) const {
554 st->print_cr("Shenandoah Heap");
555 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
556 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
557 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
558 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
559 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
560 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
561 num_regions(),
562 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
563 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
564
565 st->print("Status: ");
566 if (has_forwarded_objects()) st->print("has forwarded objects, ");
567 if (is_concurrent_mark_in_progress()) st->print("marking, ");
568 if (is_evacuation_in_progress()) st->print("evacuating, ");
569 if (is_update_refs_in_progress()) st->print("updating refs, ");
570 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
571 if (is_full_gc_in_progress()) st->print("full gc, ");
572 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
573 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
574 if (is_concurrent_strong_root_in_progress() &&
575 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
576
577 if (cancelled_gc()) {
578 st->print("cancelled");
579 } else {
580 st->print("not cancelled");
581 }
582 st->cr();
583
584 st->print_cr("Reserved region:");
585 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
586 p2i(reserved_region().start()),
587 p2i(reserved_region().end()));
588
589 ShenandoahCollectionSet* cset = collection_set();
590 st->print_cr("Collection set:");
591 if (cset != NULL) {
592 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
593 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
594 } else {
595 st->print_cr(" (NULL)");
596 }
597
598 st->cr();
599 MetaspaceUtils::print_on(st);
600
601 if (Verbose) {
602 st->cr();
603 print_heap_regions_on(st);
604 }
605 }
606
607 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
608 public:
609 void do_thread(Thread* thread) {
610 assert(thread != NULL, "Sanity");
611 assert(thread->is_Worker_thread(), "Only worker thread expected");
612 ShenandoahThreadLocalData::initialize_gclab(thread);
613 }
614 };
615
616 void ShenandoahHeap::post_initialize() {
617 CollectedHeap::post_initialize();
618 MutexLocker ml(Threads_lock);
619
620 ShenandoahInitWorkerGCLABClosure init_gclabs;
621 _workers->threads_do(&init_gclabs);
622
623 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
624 // Now, we will let WorkGang to initialize gclab when new worker is created.
625 _workers->set_initialize_gclab();
626 if (_safepoint_workers != NULL) {
627 _safepoint_workers->threads_do(&init_gclabs);
628 _safepoint_workers->set_initialize_gclab();
629 }
630
631 _heuristics->initialize();
632
633 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
634 }
635
636 size_t ShenandoahHeap::used() const {
637 return Atomic::load(&_used);
638 }
639
640 size_t ShenandoahHeap::committed() const {
641 return Atomic::load(&_committed);
642 }
643
644 void ShenandoahHeap::increase_committed(size_t bytes) {
645 shenandoah_assert_heaplocked_or_safepoint();
646 _committed += bytes;
647 }
648
649 void ShenandoahHeap::decrease_committed(size_t bytes) {
650 shenandoah_assert_heaplocked_or_safepoint();
651 _committed -= bytes;
652 }
653
654 void ShenandoahHeap::increase_used(size_t bytes) {
655 Atomic::add(&_used, bytes, memory_order_relaxed);
656 }
657
658 void ShenandoahHeap::set_used(size_t bytes) {
659 Atomic::store(&_used, bytes);
660 }
661
662 void ShenandoahHeap::decrease_used(size_t bytes) {
663 assert(used() >= bytes, "never decrease heap size by more than we've left");
664 Atomic::sub(&_used, bytes, memory_order_relaxed);
665 }
666
667 void ShenandoahHeap::increase_allocated(size_t bytes) {
668 Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed);
669 }
670
671 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
672 size_t bytes = words * HeapWordSize;
673 if (!waste) {
674 increase_used(bytes);
675 }
676 increase_allocated(bytes);
677 if (ShenandoahPacing) {
678 control_thread()->pacing_notify_alloc(words);
679 if (waste) {
680 pacer()->claim_for_alloc(words, true);
681 }
682 }
683 }
684
685 size_t ShenandoahHeap::capacity() const {
686 return committed();
687 }
688
689 size_t ShenandoahHeap::max_capacity() const {
690 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
691 }
692
693 size_t ShenandoahHeap::soft_max_capacity() const {
694 size_t v = Atomic::load(&_soft_max_size);
695 assert(min_capacity() <= v && v <= max_capacity(),
696 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
697 min_capacity(), v, max_capacity());
698 return v;
699 }
700
701 void ShenandoahHeap::set_soft_max_capacity(size_t v) {
702 assert(min_capacity() <= v && v <= max_capacity(),
703 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
704 min_capacity(), v, max_capacity());
705 Atomic::store(&_soft_max_size, v);
706 }
707
708 size_t ShenandoahHeap::min_capacity() const {
709 return _minimum_size;
710 }
711
712 size_t ShenandoahHeap::initial_capacity() const {
713 return _initial_size;
714 }
715
716 bool ShenandoahHeap::is_in(const void* p) const {
717 HeapWord* heap_base = (HeapWord*) base();
718 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
719 return p >= heap_base && p < last_region_end;
720 }
721
722 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
723 assert (ShenandoahUncommit, "should be enabled");
724
725 // Application allocates from the beginning of the heap, and GC allocates at
726 // the end of it. It is more efficient to uncommit from the end, so that applications
727 // could enjoy the near committed regions. GC allocations are much less frequent,
728 // and therefore can accept the committing costs.
729
730 size_t count = 0;
731 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
732 ShenandoahHeapRegion* r = get_region(i - 1);
733 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
734 ShenandoahHeapLocker locker(lock());
735 if (r->is_empty_committed()) {
736 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
737 break;
738 }
739
740 r->make_uncommitted();
741 count++;
742 }
743 }
744 SpinPause(); // allow allocators to take the lock
745 }
746
747 if (count > 0) {
748 control_thread()->notify_heap_changed();
749 }
750 }
751
752 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
753 // New object should fit the GCLAB size
754 size_t min_size = MAX2(size, PLAB::min_size());
755
756 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
757 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
758 new_size = MIN2(new_size, PLAB::max_size());
759 new_size = MAX2(new_size, PLAB::min_size());
760
761 // Record new heuristic value even if we take any shortcut. This captures
762 // the case when moderately-sized objects always take a shortcut. At some point,
763 // heuristics should catch up with them.
764 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
765
766 if (new_size < size) {
767 // New size still does not fit the object. Fall back to shared allocation.
768 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
769 return NULL;
770 }
771
772 // Retire current GCLAB, and allocate a new one.
773 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
774 gclab->retire();
775
776 size_t actual_size = 0;
777 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
778 if (gclab_buf == NULL) {
779 return NULL;
780 }
781
782 assert (size <= actual_size, "allocation should fit");
783
784 if (ZeroTLAB) {
785 // ..and clear it.
786 Copy::zero_to_words(gclab_buf, actual_size);
787 } else {
788 // ...and zap just allocated object.
789 #ifdef ASSERT
790 // Skip mangling the space corresponding to the object header to
791 // ensure that the returned space is not considered parsable by
792 // any concurrent GC thread.
793 size_t hdr_size = oopDesc::header_size();
794 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
795 #endif // ASSERT
796 }
797 gclab->set_buf(gclab_buf, actual_size);
798 return gclab->allocate(size);
799 }
800
801 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
802 size_t requested_size,
803 size_t* actual_size) {
804 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
805 HeapWord* res = allocate_memory(req);
806 if (res != NULL) {
807 *actual_size = req.actual_size();
808 } else {
809 *actual_size = 0;
810 }
811 return res;
812 }
813
814 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
815 size_t word_size,
816 size_t* actual_size) {
817 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
818 HeapWord* res = allocate_memory(req);
819 if (res != NULL) {
820 *actual_size = req.actual_size();
821 } else {
822 *actual_size = 0;
823 }
824 return res;
825 }
826
827 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
828 intptr_t pacer_epoch = 0;
829 bool in_new_region = false;
830 HeapWord* result = NULL;
831
832 if (req.is_mutator_alloc()) {
833 if (ShenandoahPacing) {
834 pacer()->pace_for_alloc(req.size());
835 pacer_epoch = pacer()->epoch();
836 }
837
838 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
839 result = allocate_memory_under_lock(req, in_new_region);
840 }
841
842 // Allocation failed, block until control thread reacted, then retry allocation.
843 //
844 // It might happen that one of the threads requesting allocation would unblock
845 // way later after GC happened, only to fail the second allocation, because
846 // other threads have already depleted the free storage. In this case, a better
847 // strategy is to try again, as long as GC makes progress.
848 //
849 // Then, we need to make sure the allocation was retried after at least one
850 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
851
852 size_t tries = 0;
853
854 while (result == NULL && _progress_last_gc.is_set()) {
855 tries++;
856 control_thread()->handle_alloc_failure(req);
857 result = allocate_memory_under_lock(req, in_new_region);
858 }
859
860 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
861 tries++;
862 control_thread()->handle_alloc_failure(req);
863 result = allocate_memory_under_lock(req, in_new_region);
864 }
865
866 } else {
867 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
868 result = allocate_memory_under_lock(req, in_new_region);
869 // Do not call handle_alloc_failure() here, because we cannot block.
870 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
871 }
872
873 if (in_new_region) {
874 control_thread()->notify_heap_changed();
875 }
876
877 if (result != NULL) {
878 size_t requested = req.size();
879 size_t actual = req.actual_size();
880
881 assert (req.is_lab_alloc() || (requested == actual),
882 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
883 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
884
885 if (req.is_mutator_alloc()) {
886 notify_mutator_alloc_words(actual, false);
887
888 // If we requested more than we were granted, give the rest back to pacer.
889 // This only matters if we are in the same pacing epoch: do not try to unpace
890 // over the budget for the other phase.
891 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
892 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
893 }
894 } else {
895 increase_used(actual*HeapWordSize);
896 }
897 }
898
899 return result;
900 }
901
902 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
903 ShenandoahHeapLocker locker(lock());
904 return _free_set->allocate(req, in_new_region);
905 }
906
907 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
908 bool* gc_overhead_limit_was_exceeded) {
909 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
910 return allocate_memory(req);
911 }
912
913 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
914 size_t size,
915 Metaspace::MetadataType mdtype) {
916 MetaWord* result;
917
918 // Inform metaspace OOM to GC heuristics if class unloading is possible.
919 if (heuristics()->can_unload_classes()) {
920 ShenandoahHeuristics* h = heuristics();
921 h->record_metaspace_oom();
922 }
923
924 // Expand and retry allocation
925 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
926 if (result != NULL) {
927 return result;
928 }
929
930 // Start full GC
931 collect(GCCause::_metadata_GC_clear_soft_refs);
932
933 // Retry allocation
934 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
935 if (result != NULL) {
936 return result;
937 }
938
939 // Expand and retry allocation
940 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
941 if (result != NULL) {
942 return result;
943 }
944
945 // Out of memory
946 return NULL;
947 }
948
949 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
950 private:
951 ShenandoahHeap* const _heap;
952 Thread* const _thread;
953 public:
954 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
955 _heap(heap), _thread(Thread::current()) {}
956
957 void do_object(oop p) {
958 shenandoah_assert_marked(NULL, p);
959 if (!ShenandoahForwarding::is_forwarded(p)) {
960 _heap->evacuate_object(p, _thread);
961 }
962 }
963 };
964
965 class ShenandoahEvacuationTask : public AbstractGangTask {
966 private:
967 ShenandoahHeap* const _sh;
968 ShenandoahCollectionSet* const _cs;
969 bool _concurrent;
970 public:
971 ShenandoahEvacuationTask(ShenandoahHeap* sh,
972 ShenandoahCollectionSet* cs,
973 bool concurrent) :
974 AbstractGangTask("Shenandoah Evacuation"),
975 _sh(sh),
976 _cs(cs),
977 _concurrent(concurrent)
978 {}
979
980 void work(uint worker_id) {
981 if (_concurrent) {
982 ShenandoahConcurrentWorkerSession worker_session(worker_id);
983 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
984 ShenandoahEvacOOMScope oom_evac_scope;
985 do_work();
986 } else {
987 ShenandoahParallelWorkerSession worker_session(worker_id);
988 ShenandoahEvacOOMScope oom_evac_scope;
989 do_work();
990 }
991 }
992
993 private:
994 void do_work() {
995 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
996 ShenandoahHeapRegion* r;
997 while ((r =_cs->claim_next()) != NULL) {
998 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
999 _sh->marked_object_iterate(r, &cl);
1000
1001 if (ShenandoahPacing) {
1002 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
1003 }
1004
1005 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1006 break;
1007 }
1008 }
1009 }
1010 };
1011
1012 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
1013 ShenandoahEvacuationTask task(this, _collection_set, concurrent);
1014 workers()->run_task(&task);
1015 }
1016
1017 void ShenandoahHeap::trash_cset_regions() {
1018 ShenandoahHeapLocker locker(lock());
1019
1020 ShenandoahCollectionSet* set = collection_set();
1021 ShenandoahHeapRegion* r;
1022 set->clear_current_index();
1023 while ((r = set->next()) != NULL) {
1024 r->make_trash();
1025 }
1026 collection_set()->clear();
1027 }
1028
1029 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1030 st->print_cr("Heap Regions:");
1031 st->print_cr("Region state: EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HP=pinned humongous start");
1032 st->print_cr(" HC=humongous continuation, CS=collection set, TR=trash, P=pinned, CSP=pinned collection set");
1033 st->print_cr("BTE=bottom/top/end, TAMS=top-at-mark-start");
1034 st->print_cr("UWM=update watermark, U=used");
1035 st->print_cr("T=TLAB allocs, G=GCLAB allocs");
1036 st->print_cr("S=shared allocs, L=live data");
1037 st->print_cr("CP=critical pins");
1038
1039 for (size_t i = 0; i < num_regions(); i++) {
1040 get_region(i)->print_on(st);
1041 }
1042 }
1043
1044 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1045 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1046
1047 oop humongous_obj = cast_to_oop(start->bottom());
1048 size_t size = humongous_obj->size();
1049 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1050 size_t index = start->index() + required_regions - 1;
1051
1052 assert(!start->has_live(), "liveness must be zero");
1053
1054 for(size_t i = 0; i < required_regions; i++) {
1055 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1056 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1057 ShenandoahHeapRegion* region = get_region(index --);
1058
1059 assert(region->is_humongous(), "expect correct humongous start or continuation");
1060 assert(!region->is_cset(), "Humongous region should not be in collection set");
1061
1062 region->make_trash_immediate();
1063 }
1064 }
1065
1066 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1067 public:
1068 ShenandoahCheckCleanGCLABClosure() {}
1069 void do_thread(Thread* thread) {
1070 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1071 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1072 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1073 }
1074 };
1075
1076 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1077 private:
1078 bool const _resize;
1079 public:
1080 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1081 void do_thread(Thread* thread) {
1082 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1083 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1084 gclab->retire();
1085 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1086 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1087 }
1088 }
1089 };
1090
1091 void ShenandoahHeap::labs_make_parsable() {
1092 assert(UseTLAB, "Only call with UseTLAB");
1093
1094 ShenandoahRetireGCLABClosure cl(false);
1095
1096 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1097 ThreadLocalAllocBuffer& tlab = t->tlab();
1098 tlab.make_parsable();
1099 cl.do_thread(t);
1100 }
1101
1102 workers()->threads_do(&cl);
1103 }
1104
1105 void ShenandoahHeap::tlabs_retire(bool resize) {
1106 assert(UseTLAB, "Only call with UseTLAB");
1107 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1108
1109 ThreadLocalAllocStats stats;
1110
1111 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1112 ThreadLocalAllocBuffer& tlab = t->tlab();
1113 tlab.retire(&stats);
1114 if (resize) {
1115 tlab.resize();
1116 }
1117 }
1118
1119 stats.publish();
1120
1121 #ifdef ASSERT
1122 ShenandoahCheckCleanGCLABClosure cl;
1123 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1124 cl.do_thread(t);
1125 }
1126 workers()->threads_do(&cl);
1127 #endif
1128 }
1129
1130 void ShenandoahHeap::gclabs_retire(bool resize) {
1131 assert(UseTLAB, "Only call with UseTLAB");
1132 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1133
1134 ShenandoahRetireGCLABClosure cl(resize);
1135 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1136 cl.do_thread(t);
1137 }
1138 workers()->threads_do(&cl);
1139
1140 if (safepoint_workers() != NULL) {
1141 safepoint_workers()->threads_do(&cl);
1142 }
1143 }
1144
1145 // Returns size in bytes
1146 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1147 if (ShenandoahElasticTLAB) {
1148 // With Elastic TLABs, return the max allowed size, and let the allocation path
1149 // figure out the safe size for current allocation.
1150 return ShenandoahHeapRegion::max_tlab_size_bytes();
1151 } else {
1152 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1153 }
1154 }
1155
1156 size_t ShenandoahHeap::max_tlab_size() const {
1157 // Returns size in words
1158 return ShenandoahHeapRegion::max_tlab_size_words();
1159 }
1160
1161 void ShenandoahHeap::collect(GCCause::Cause cause) {
1162 control_thread()->request_gc(cause);
1163 }
1164
1165 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1166 //assert(false, "Shouldn't need to do full collections");
1167 }
1168
1169 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1170 ShenandoahHeapRegion* r = heap_region_containing(addr);
1171 if (r != NULL) {
1172 return r->block_start(addr);
1173 }
1174 return NULL;
1175 }
1176
1177 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1178 ShenandoahHeapRegion* r = heap_region_containing(addr);
1179 return r->block_is_obj(addr);
1180 }
1181
1182 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1183 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1184 }
1185
1186 void ShenandoahHeap::prepare_for_verify() {
1187 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1188 labs_make_parsable();
1189 }
1190 }
1191
1192 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1193 tcl->do_thread(_control_thread);
1194 workers()->threads_do(tcl);
1195 if (_safepoint_workers != NULL) {
1196 _safepoint_workers->threads_do(tcl);
1197 }
1198 if (ShenandoahStringDedup::is_enabled()) {
1199 ShenandoahStringDedup::threads_do(tcl);
1200 }
1201 }
1202
1203 void ShenandoahHeap::print_tracing_info() const {
1204 LogTarget(Info, gc, stats) lt;
1205 if (lt.is_enabled()) {
1206 ResourceMark rm;
1207 LogStream ls(lt);
1208
1209 phase_timings()->print_global_on(&ls);
1210
1211 ls.cr();
1212 ls.cr();
1213
1214 shenandoah_policy()->print_gc_stats(&ls);
1215
1216 ls.cr();
1217 ls.cr();
1218 }
1219 }
1220
1221 void ShenandoahHeap::verify(VerifyOption vo) {
1222 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1223 if (ShenandoahVerify) {
1224 verifier()->verify_generic(vo);
1225 } else {
1226 // TODO: Consider allocating verification bitmaps on demand,
1227 // and turn this on unconditionally.
1228 }
1229 }
1230 }
1231 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1232 return _free_set->capacity();
1233 }
1234
1235 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1236 private:
1237 MarkBitMap* _bitmap;
1238 ShenandoahScanObjectStack* _oop_stack;
1239 ShenandoahHeap* const _heap;
1240 ShenandoahMarkingContext* const _marking_context;
1241
1242 template <class T>
1243 void do_oop_work(T* p) {
1244 T o = RawAccess<>::oop_load(p);
1245 if (!CompressedOops::is_null(o)) {
1246 oop obj = CompressedOops::decode_not_null(o);
1247 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1248 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1249 return;
1250 }
1251 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1252
1253 assert(oopDesc::is_oop(obj), "must be a valid oop");
1254 if (!_bitmap->is_marked(obj)) {
1255 _bitmap->mark(obj);
1256 _oop_stack->push(obj);
1257 }
1258 }
1259 }
1260 public:
1261 ObjectIterateScanRootClosure(MarkBitMap* bitmap, ShenandoahScanObjectStack* oop_stack) :
1262 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1263 _marking_context(_heap->marking_context()) {}
1264 void do_oop(oop* p) { do_oop_work(p); }
1265 void do_oop(narrowOop* p) { do_oop_work(p); }
1266 };
1267
1268 /*
1269 * This is public API, used in preparation of object_iterate().
1270 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1271 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1272 * control, we call SH::tlabs_retire, SH::gclabs_retire.
1273 */
1274 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1275 // No-op.
1276 }
1277
1278 /*
1279 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1280 *
1281 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1282 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1283 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1284 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1285 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1286 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1287 * wiped the bitmap in preparation for next marking).
1288 *
1289 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1290 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1291 * is allowed to report dead objects, but is not required to do so.
1292 */
1293 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1294 // Reset bitmap
1295 if (!prepare_aux_bitmap_for_iteration())
1296 return;
1297
1298 ShenandoahScanObjectStack oop_stack;
1299 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1300 // Seed the stack with root scan
1301 scan_roots_for_iteration(&oop_stack, &oops);
1302
1303 // Work through the oop stack to traverse heap
1304 while (! oop_stack.is_empty()) {
1305 oop obj = oop_stack.pop();
1306 assert(oopDesc::is_oop(obj), "must be a valid oop");
1307 shenandoah_assert_not_in_cset_except(NULL, obj, cancelled_gc());
1308 cl->do_object(obj);
1309 obj->oop_iterate(&oops);
1310 }
1311
1312 assert(oop_stack.is_empty(), "should be empty");
1313 // Reclaim bitmap
1314 reclaim_aux_bitmap_for_iteration();
1315 }
1316
1317 bool ShenandoahHeap::prepare_aux_bitmap_for_iteration() {
1318 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1319
1320 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1321 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1322 return false;
1323 }
1324 // Reset bitmap
1325 _aux_bit_map.clear();
1326 return true;
1327 }
1328
1329 void ShenandoahHeap::scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops) {
1330 // Process GC roots according to current GC cycle
1331 // This populates the work stack with initial objects
1332 // It is important to relinquish the associated locks before diving
1333 // into heap dumper
1334 ShenandoahHeapIterationRootScanner rp;
1335 rp.roots_do(oops);
1336 }
1337
1338 void ShenandoahHeap::reclaim_aux_bitmap_for_iteration() {
1339 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1340 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1341 }
1342 }
1343
1344 // Closure for parallelly iterate objects
1345 class ShenandoahObjectIterateParScanClosure : public BasicOopIterateClosure {
1346 private:
1347 MarkBitMap* _bitmap;
1348 ShenandoahObjToScanQueue* _queue;
1349 ShenandoahHeap* const _heap;
1350 ShenandoahMarkingContext* const _marking_context;
1351
1352 template <class T>
1353 void do_oop_work(T* p) {
1354 T o = RawAccess<>::oop_load(p);
1355 if (!CompressedOops::is_null(o)) {
1356 oop obj = CompressedOops::decode_not_null(o);
1357 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1358 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1359 return;
1360 }
1361 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1362
1363 assert(oopDesc::is_oop(obj), "Must be a valid oop");
1364 if (_bitmap->par_mark(obj)) {
1365 _queue->push(ShenandoahMarkTask(obj));
1366 }
1367 }
1368 }
1369 public:
1370 ShenandoahObjectIterateParScanClosure(MarkBitMap* bitmap, ShenandoahObjToScanQueue* q) :
1371 _bitmap(bitmap), _queue(q), _heap(ShenandoahHeap::heap()),
1372 _marking_context(_heap->marking_context()) {}
1373 void do_oop(oop* p) { do_oop_work(p); }
1374 void do_oop(narrowOop* p) { do_oop_work(p); }
1375 };
1376
1377 // Object iterator for parallel heap iteraion.
1378 // The root scanning phase happenes in construction as a preparation of
1379 // parallel marking queues.
1380 // Every worker processes it's own marking queue. work-stealing is used
1381 // to balance workload.
1382 class ShenandoahParallelObjectIterator : public ParallelObjectIteratorImpl {
1383 private:
1384 uint _num_workers;
1385 bool _init_ready;
1386 MarkBitMap* _aux_bit_map;
1387 ShenandoahHeap* _heap;
1388 ShenandoahScanObjectStack _roots_stack; // global roots stack
1389 ShenandoahObjToScanQueueSet* _task_queues;
1390 public:
1391 ShenandoahParallelObjectIterator(uint num_workers, MarkBitMap* bitmap) :
1392 _num_workers(num_workers),
1393 _init_ready(false),
1394 _aux_bit_map(bitmap),
1395 _heap(ShenandoahHeap::heap()) {
1396 // Initialize bitmap
1397 _init_ready = _heap->prepare_aux_bitmap_for_iteration();
1398 if (!_init_ready) {
1399 return;
1400 }
1401
1402 ObjectIterateScanRootClosure oops(_aux_bit_map, &_roots_stack);
1403 _heap->scan_roots_for_iteration(&_roots_stack, &oops);
1404
1405 _init_ready = prepare_worker_queues();
1406 }
1407
1408 ~ShenandoahParallelObjectIterator() {
1409 // Reclaim bitmap
1410 _heap->reclaim_aux_bitmap_for_iteration();
1411 // Reclaim queue for workers
1412 if (_task_queues!= NULL) {
1413 for (uint i = 0; i < _num_workers; ++i) {
1414 ShenandoahObjToScanQueue* q = _task_queues->queue(i);
1415 if (q != NULL) {
1416 delete q;
1417 _task_queues->register_queue(i, NULL);
1418 }
1419 }
1420 delete _task_queues;
1421 _task_queues = NULL;
1422 }
1423 }
1424
1425 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
1426 if (_init_ready) {
1427 object_iterate_parallel(cl, worker_id, _task_queues);
1428 }
1429 }
1430
1431 private:
1432 // Divide global root_stack into worker queues
1433 bool prepare_worker_queues() {
1434 _task_queues = new ShenandoahObjToScanQueueSet((int) _num_workers);
1435 // Initialize queues for every workers
1436 for (uint i = 0; i < _num_workers; ++i) {
1437 ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue();
1438 task_queue->initialize();
1439 _task_queues->register_queue(i, task_queue);
1440 }
1441 // Divide roots among the workers. Assume that object referencing distribution
1442 // is related with root kind, use round-robin to make every worker have same chance
1443 // to process every kind of roots
1444 size_t roots_num = _roots_stack.size();
1445 if (roots_num == 0) {
1446 // No work to do
1447 return false;
1448 }
1449
1450 for (uint j = 0; j < roots_num; j++) {
1451 uint stack_id = j % _num_workers;
1452 oop obj = _roots_stack.pop();
1453 _task_queues->queue(stack_id)->push(ShenandoahMarkTask(obj));
1454 }
1455 return true;
1456 }
1457
1458 void object_iterate_parallel(ObjectClosure* cl,
1459 uint worker_id,
1460 ShenandoahObjToScanQueueSet* queue_set) {
1461 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1462 assert(queue_set != NULL, "task queue must not be NULL");
1463
1464 ShenandoahObjToScanQueue* q = queue_set->queue(worker_id);
1465 assert(q != NULL, "object iterate queue must not be NULL");
1466
1467 ShenandoahMarkTask t;
1468 ShenandoahObjectIterateParScanClosure oops(_aux_bit_map, q);
1469
1470 // Work through the queue to traverse heap.
1471 // Steal when there is no task in queue.
1472 while (q->pop(t) || queue_set->steal(worker_id, t)) {
1473 oop obj = t.obj();
1474 assert(oopDesc::is_oop(obj), "must be a valid oop");
1475 cl->do_object(obj);
1476 obj->oop_iterate(&oops);
1477 }
1478 assert(q->is_empty(), "should be empty");
1479 }
1480 };
1481
1482 ParallelObjectIteratorImpl* ShenandoahHeap::parallel_object_iterator(uint workers) {
1483 return new ShenandoahParallelObjectIterator(workers, &_aux_bit_map);
1484 }
1485
1486 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1487 void ShenandoahHeap::keep_alive(oop obj) {
1488 if (is_concurrent_mark_in_progress() && (obj != NULL)) {
1489 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1490 }
1491 }
1492
1493 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1494 for (size_t i = 0; i < num_regions(); i++) {
1495 ShenandoahHeapRegion* current = get_region(i);
1496 blk->heap_region_do(current);
1497 }
1498 }
1499
1500 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1501 private:
1502 ShenandoahHeap* const _heap;
1503 ShenandoahHeapRegionClosure* const _blk;
1504
1505 shenandoah_padding(0);
1506 volatile size_t _index;
1507 shenandoah_padding(1);
1508
1509 public:
1510 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1511 AbstractGangTask("Shenandoah Parallel Region Operation"),
1512 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1513
1514 void work(uint worker_id) {
1515 ShenandoahParallelWorkerSession worker_session(worker_id);
1516 size_t stride = ShenandoahParallelRegionStride;
1517
1518 size_t max = _heap->num_regions();
1519 while (Atomic::load(&_index) < max) {
1520 size_t cur = Atomic::fetch_and_add(&_index, stride, memory_order_relaxed);
1521 size_t start = cur;
1522 size_t end = MIN2(cur + stride, max);
1523 if (start >= max) break;
1524
1525 for (size_t i = cur; i < end; i++) {
1526 ShenandoahHeapRegion* current = _heap->get_region(i);
1527 _blk->heap_region_do(current);
1528 }
1529 }
1530 }
1531 };
1532
1533 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1534 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1535 if (num_regions() > ShenandoahParallelRegionStride) {
1536 ShenandoahParallelHeapRegionTask task(blk);
1537 workers()->run_task(&task);
1538 } else {
1539 heap_region_iterate(blk);
1540 }
1541 }
1542
1543 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1544 private:
1545 ShenandoahMarkingContext* const _ctx;
1546 public:
1547 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1548
1549 void heap_region_do(ShenandoahHeapRegion* r) {
1550 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1551 if (r->is_active()) {
1552 // Check if region needs updating its TAMS. We have updated it already during concurrent
1553 // reset, so it is very likely we don't need to do another write here.
1554 if (_ctx->top_at_mark_start(r) != r->top()) {
1555 _ctx->capture_top_at_mark_start(r);
1556 }
1557 } else {
1558 assert(_ctx->top_at_mark_start(r) == r->top(),
1559 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1560 }
1561 }
1562
1563 bool is_thread_safe() { return true; }
1564 };
1565
1566 class ShenandoahRendezvousClosure : public HandshakeClosure {
1567 public:
1568 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
1569 inline void do_thread(Thread* thread) {}
1570 };
1571
1572 void ShenandoahHeap::rendezvous_threads() {
1573 ShenandoahRendezvousClosure cl;
1574 Handshake::execute(&cl);
1575 }
1576
1577 void ShenandoahHeap::recycle_trash() {
1578 free_set()->recycle_trash();
1579 }
1580
1581 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1582 private:
1583 ShenandoahMarkingContext* const _ctx;
1584 public:
1585 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1586
1587 void heap_region_do(ShenandoahHeapRegion* r) {
1588 if (r->is_active()) {
1589 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1590 // anyway to capture any updates that happened since now.
1591 r->clear_live_data();
1592 _ctx->capture_top_at_mark_start(r);
1593 }
1594 }
1595
1596 bool is_thread_safe() { return true; }
1597 };
1598
1599 void ShenandoahHeap::prepare_gc() {
1600 reset_mark_bitmap();
1601
1602 ShenandoahResetUpdateRegionStateClosure cl;
1603 parallel_heap_region_iterate(&cl);
1604 }
1605
1606 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1607 private:
1608 ShenandoahMarkingContext* const _ctx;
1609 ShenandoahHeapLock* const _lock;
1610
1611 public:
1612 ShenandoahFinalMarkUpdateRegionStateClosure() :
1613 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1614
1615 void heap_region_do(ShenandoahHeapRegion* r) {
1616 if (r->is_active()) {
1617 // All allocations past TAMS are implicitly live, adjust the region data.
1618 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1619 HeapWord *tams = _ctx->top_at_mark_start(r);
1620 HeapWord *top = r->top();
1621 if (top > tams) {
1622 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1623 }
1624
1625 // We are about to select the collection set, make sure it knows about
1626 // current pinning status. Also, this allows trashing more regions that
1627 // now have their pinning status dropped.
1628 if (r->is_pinned()) {
1629 if (r->pin_count() == 0) {
1630 ShenandoahHeapLocker locker(_lock);
1631 r->make_unpinned();
1632 }
1633 } else {
1634 if (r->pin_count() > 0) {
1635 ShenandoahHeapLocker locker(_lock);
1636 r->make_pinned();
1637 }
1638 }
1639
1640 // Remember limit for updating refs. It's guaranteed that we get no
1641 // from-space-refs written from here on.
1642 r->set_update_watermark_at_safepoint(r->top());
1643 } else {
1644 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1645 assert(_ctx->top_at_mark_start(r) == r->top(),
1646 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1647 }
1648 }
1649
1650 bool is_thread_safe() { return true; }
1651 };
1652
1653 void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) {
1654 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
1655 {
1656 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states :
1657 ShenandoahPhaseTimings::degen_gc_final_update_region_states);
1658 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1659 parallel_heap_region_iterate(&cl);
1660
1661 assert_pinned_region_status();
1662 }
1663
1664 {
1665 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset :
1666 ShenandoahPhaseTimings::degen_gc_choose_cset);
1667 ShenandoahHeapLocker locker(lock());
1668 _collection_set->clear();
1669 heuristics()->choose_collection_set(_collection_set);
1670 }
1671
1672 {
1673 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset :
1674 ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset);
1675 ShenandoahHeapLocker locker(lock());
1676 _free_set->rebuild();
1677 }
1678 }
1679
1680 void ShenandoahHeap::do_class_unloading() {
1681 _unloader.unload();
1682 }
1683
1684 void ShenandoahHeap::stw_weak_refs(bool full_gc) {
1685 // Weak refs processing
1686 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
1687 : ShenandoahPhaseTimings::degen_gc_weakrefs;
1688 ShenandoahTimingsTracker t(phase);
1689 ShenandoahGCWorkerPhase worker_phase(phase);
1690 ref_processor()->process_references(phase, workers(), false /* concurrent */);
1691 }
1692
1693 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
1694 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1695
1696 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
1697 // make them parsable for update code to work correctly. Plus, we can compute new sizes
1698 // for future GCLABs here.
1699 if (UseTLAB) {
1700 ShenandoahGCPhase phase(concurrent ?
1701 ShenandoahPhaseTimings::init_update_refs_manage_gclabs :
1702 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs);
1703 gclabs_retire(ResizeTLAB);
1704 }
1705
1706 _update_refs_iterator.reset();
1707 }
1708
1709 void ShenandoahHeap::set_gc_state_all_threads() {
1710 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint");
1711 if (_gc_state_changed) {
1712 _gc_state_changed = false;
1713 char state = gc_state();
1714 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1715 ShenandoahThreadLocalData::set_gc_state(t, state);
1716 }
1717 }
1718 }
1719
1720 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1721 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint");
1722 _gc_state.set_cond(mask, value);
1723 _gc_state_changed = true;
1724 }
1725
1726 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1727 assert(!has_forwarded_objects(), "Not expected before/after mark phase");
1728 set_gc_state_mask(MARKING, in_progress);
1729 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1730 }
1731
1732 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1733 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1734 set_gc_state_mask(EVACUATION, in_progress);
1735 }
1736
1737 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
1738 if (in_progress) {
1739 _concurrent_strong_root_in_progress.set();
1740 } else {
1741 _concurrent_strong_root_in_progress.unset();
1742 }
1743 }
1744
1745 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) {
1746 set_gc_state_mask(WEAK_ROOTS, cond);
1747 }
1748
1749 GCTracer* ShenandoahHeap::tracer() {
1750 return shenandoah_policy()->tracer();
1751 }
1752
1753 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1754 return _free_set->used();
1755 }
1756
1757 bool ShenandoahHeap::try_cancel_gc() {
1758 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1759 return prev == CANCELLABLE;
1760 }
1761
1762 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1763 if (try_cancel_gc()) {
1764 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1765 log_info(gc)("%s", msg.buffer());
1766 Events::log(Thread::current(), "%s", msg.buffer());
1767 }
1768 }
1769
1770 uint ShenandoahHeap::max_workers() {
1771 return _max_workers;
1772 }
1773
1774 void ShenandoahHeap::stop() {
1775 // The shutdown sequence should be able to terminate when GC is running.
1776
1777 // Step 0. Notify policy to disable event recording.
1778 _shenandoah_policy->record_shutdown();
1779
1780 // Step 1. Notify control thread that we are in shutdown.
1781 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1782 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1783 control_thread()->prepare_for_graceful_shutdown();
1784
1785 // Step 2. Notify GC workers that we are cancelling GC.
1786 cancel_gc(GCCause::_shenandoah_stop_vm);
1787
1788 // Step 3. Wait until GC worker exits normally.
1789 control_thread()->stop();
1790 }
1791
1792 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
1793 if (!unload_classes()) return;
1794 // Unload classes and purge SystemDictionary.
1795 {
1796 ShenandoahPhaseTimings::Phase phase = full_gc ?
1797 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1798 ShenandoahPhaseTimings::degen_gc_purge_class_unload;
1799 ShenandoahGCPhase gc_phase(phase);
1800 ShenandoahGCWorkerPhase worker_phase(phase);
1801 bool purged_class = SystemDictionary::do_unloading(gc_timer());
1802
1803 ShenandoahIsAliveSelector is_alive;
1804 uint num_workers = _workers->active_workers();
1805 ShenandoahClassUnloadingTask unlink_task(phase, is_alive.is_alive_closure(), num_workers, purged_class);
1806 _workers->run_task(&unlink_task);
1807 }
1808
1809 {
1810 ShenandoahGCPhase phase(full_gc ?
1811 ShenandoahPhaseTimings::full_gc_purge_cldg :
1812 ShenandoahPhaseTimings::degen_gc_purge_cldg);
1813 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
1814 }
1815 // Resize and verify metaspace
1816 MetaspaceGC::compute_new_size();
1817 DEBUG_ONLY(MetaspaceUtils::verify();)
1818 }
1819
1820 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
1821 // so they should not have forwarded oops.
1822 // However, we do need to "null" dead oops in the roots, if can not be done
1823 // in concurrent cycles.
1824 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
1825 uint num_workers = _workers->active_workers();
1826 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
1827 ShenandoahPhaseTimings::full_gc_purge_weak_par :
1828 ShenandoahPhaseTimings::degen_gc_purge_weak_par;
1829 ShenandoahGCPhase phase(timing_phase);
1830 ShenandoahGCWorkerPhase worker_phase(timing_phase);
1831 // Cleanup weak roots
1832 if (has_forwarded_objects()) {
1833 ShenandoahForwardedIsAliveClosure is_alive;
1834 ShenandoahUpdateRefsClosure keep_alive;
1835 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
1836 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers);
1837 _workers->run_task(&cleaning_task);
1838 } else {
1839 ShenandoahIsAliveClosure is_alive;
1840 #ifdef ASSERT
1841 ShenandoahAssertNotForwardedClosure verify_cl;
1842 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
1843 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers);
1844 #else
1845 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
1846 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers);
1847 #endif
1848 _workers->run_task(&cleaning_task);
1849 }
1850 }
1851
1852 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
1853 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1854 assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC");
1855 ShenandoahGCPhase phase(full_gc ?
1856 ShenandoahPhaseTimings::full_gc_purge :
1857 ShenandoahPhaseTimings::degen_gc_purge);
1858 stw_weak_refs(full_gc);
1859 stw_process_weak_roots(full_gc);
1860 stw_unload_classes(full_gc);
1861 }
1862
1863 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
1864 set_gc_state_mask(HAS_FORWARDED, cond);
1865 }
1866
1867 void ShenandoahHeap::set_unload_classes(bool uc) {
1868 _unload_classes.set_cond(uc);
1869 }
1870
1871 bool ShenandoahHeap::unload_classes() const {
1872 return _unload_classes.is_set();
1873 }
1874
1875 address ShenandoahHeap::in_cset_fast_test_addr() {
1876 ShenandoahHeap* heap = ShenandoahHeap::heap();
1877 assert(heap->collection_set() != NULL, "Sanity");
1878 return (address) heap->collection_set()->biased_map_address();
1879 }
1880
1881 address ShenandoahHeap::cancelled_gc_addr() {
1882 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
1883 }
1884
1885 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
1886 return Atomic::load(&_bytes_allocated_since_gc_start);
1887 }
1888
1889 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
1890 Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0);
1891 }
1892
1893 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
1894 _degenerated_gc_in_progress.set_cond(in_progress);
1895 }
1896
1897 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
1898 _full_gc_in_progress.set_cond(in_progress);
1899 }
1900
1901 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
1902 assert (is_full_gc_in_progress(), "should be");
1903 _full_gc_move_in_progress.set_cond(in_progress);
1904 }
1905
1906 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
1907 set_gc_state_mask(UPDATEREFS, in_progress);
1908 }
1909
1910 void ShenandoahHeap::register_nmethod(nmethod* nm) {
1911 ShenandoahCodeRoots::register_nmethod(nm);
1912 }
1913
1914 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
1915 ShenandoahCodeRoots::unregister_nmethod(nm);
1916 }
1917
1918 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
1919 ShenandoahCodeRoots::flush_nmethod(nm);
1920 }
1921
1922 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
1923 heap_region_containing(o)->record_pin();
1924 return o;
1925 }
1926
1927 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
1928 ShenandoahHeapRegion* r = heap_region_containing(o);
1929 assert(r != NULL, "Sanity");
1930 assert(r->pin_count() > 0, "Region " SIZE_FORMAT " should have non-zero pins", r->index());
1931 r->record_unpin();
1932 }
1933
1934 void ShenandoahHeap::sync_pinned_region_status() {
1935 ShenandoahHeapLocker locker(lock());
1936
1937 for (size_t i = 0; i < num_regions(); i++) {
1938 ShenandoahHeapRegion *r = get_region(i);
1939 if (r->is_active()) {
1940 if (r->is_pinned()) {
1941 if (r->pin_count() == 0) {
1942 r->make_unpinned();
1943 }
1944 } else {
1945 if (r->pin_count() > 0) {
1946 r->make_pinned();
1947 }
1948 }
1949 }
1950 }
1951
1952 assert_pinned_region_status();
1953 }
1954
1955 #ifdef ASSERT
1956 void ShenandoahHeap::assert_pinned_region_status() {
1957 for (size_t i = 0; i < num_regions(); i++) {
1958 ShenandoahHeapRegion* r = get_region(i);
1959 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
1960 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
1961 }
1962 }
1963 #endif
1964
1965 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
1966 return _gc_timer;
1967 }
1968
1969 void ShenandoahHeap::prepare_concurrent_roots() {
1970 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1971 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1972 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
1973 set_concurrent_weak_root_in_progress(true);
1974 if (unload_classes()) {
1975 _unloader.prepare();
1976 }
1977 }
1978
1979 void ShenandoahHeap::finish_concurrent_roots() {
1980 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1981 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1982 if (unload_classes()) {
1983 _unloader.finish();
1984 }
1985 }
1986
1987 #ifdef ASSERT
1988 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
1989 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
1990
1991 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1992 if (UseDynamicNumberOfGCThreads) {
1993 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
1994 } else {
1995 // Use ParallelGCThreads inside safepoints
1996 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
1997 }
1998 } else {
1999 if (UseDynamicNumberOfGCThreads) {
2000 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2001 } else {
2002 // Use ConcGCThreads outside safepoints
2003 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2004 }
2005 }
2006 }
2007 #endif
2008
2009 ShenandoahVerifier* ShenandoahHeap::verifier() {
2010 guarantee(ShenandoahVerify, "Should be enabled");
2011 assert (_verifier != NULL, "sanity");
2012 return _verifier;
2013 }
2014
2015 template<bool CONCURRENT>
2016 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2017 private:
2018 ShenandoahHeap* _heap;
2019 ShenandoahRegionIterator* _regions;
2020 public:
2021 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
2022 AbstractGangTask("Shenandoah Update References"),
2023 _heap(ShenandoahHeap::heap()),
2024 _regions(regions) {
2025 }
2026
2027 void work(uint worker_id) {
2028 if (CONCURRENT) {
2029 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2030 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2031 do_work<ShenandoahConcUpdateRefsClosure>();
2032 } else {
2033 ShenandoahParallelWorkerSession worker_session(worker_id);
2034 do_work<ShenandoahSTWUpdateRefsClosure>();
2035 }
2036 }
2037
2038 private:
2039 template<class T>
2040 void do_work() {
2041 T cl;
2042 ShenandoahHeapRegion* r = _regions->next();
2043 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2044 while (r != NULL) {
2045 HeapWord* update_watermark = r->get_update_watermark();
2046 assert (update_watermark >= r->bottom(), "sanity");
2047 if (r->is_active() && !r->is_cset()) {
2048 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2049 }
2050 if (ShenandoahPacing) {
2051 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2052 }
2053 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2054 return;
2055 }
2056 r = _regions->next();
2057 }
2058 }
2059 };
2060
2061 void ShenandoahHeap::update_heap_references(bool concurrent) {
2062 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2063
2064 if (concurrent) {
2065 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator);
2066 workers()->run_task(&task);
2067 } else {
2068 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
2069 workers()->run_task(&task);
2070 }
2071 }
2072
2073
2074 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2075 private:
2076 ShenandoahHeapLock* const _lock;
2077
2078 public:
2079 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2080
2081 void heap_region_do(ShenandoahHeapRegion* r) {
2082 // Drop unnecessary "pinned" state from regions that does not have CP marks
2083 // anymore, as this would allow trashing them.
2084
2085 if (r->is_active()) {
2086 if (r->is_pinned()) {
2087 if (r->pin_count() == 0) {
2088 ShenandoahHeapLocker locker(_lock);
2089 r->make_unpinned();
2090 }
2091 } else {
2092 if (r->pin_count() > 0) {
2093 ShenandoahHeapLocker locker(_lock);
2094 r->make_pinned();
2095 }
2096 }
2097 }
2098 }
2099
2100 bool is_thread_safe() { return true; }
2101 };
2102
2103 void ShenandoahHeap::update_heap_region_states(bool concurrent) {
2104 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2105 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2106
2107 {
2108 ShenandoahGCPhase phase(concurrent ?
2109 ShenandoahPhaseTimings::final_update_refs_update_region_states :
2110 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states);
2111 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2112 parallel_heap_region_iterate(&cl);
2113
2114 assert_pinned_region_status();
2115 }
2116
2117 {
2118 ShenandoahGCPhase phase(concurrent ?
2119 ShenandoahPhaseTimings::final_update_refs_trash_cset :
2120 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset);
2121 trash_cset_regions();
2122 }
2123 }
2124
2125 void ShenandoahHeap::rebuild_free_set(bool concurrent) {
2126 {
2127 ShenandoahGCPhase phase(concurrent ?
2128 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
2129 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
2130 ShenandoahHeapLocker locker(lock());
2131 _free_set->rebuild();
2132 }
2133 }
2134
2135 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2136 print_on(st);
2137 st->cr();
2138 print_heap_regions_on(st);
2139 }
2140
2141 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2142 size_t slice = r->index() / _bitmap_regions_per_slice;
2143
2144 size_t regions_from = _bitmap_regions_per_slice * slice;
2145 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2146 for (size_t g = regions_from; g < regions_to; g++) {
2147 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2148 if (skip_self && g == r->index()) continue;
2149 if (get_region(g)->is_committed()) {
2150 return true;
2151 }
2152 }
2153 return false;
2154 }
2155
2156 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2157 shenandoah_assert_heaplocked();
2158
2159 // Bitmaps in special regions do not need commits
2160 if (_bitmap_region_special) {
2161 return true;
2162 }
2163
2164 if (is_bitmap_slice_committed(r, true)) {
2165 // Some other region from the group is already committed, meaning the bitmap
2166 // slice is already committed, we exit right away.
2167 return true;
2168 }
2169
2170 // Commit the bitmap slice:
2171 size_t slice = r->index() / _bitmap_regions_per_slice;
2172 size_t off = _bitmap_bytes_per_slice * slice;
2173 size_t len = _bitmap_bytes_per_slice;
2174 char* start = (char*) _bitmap_region.start() + off;
2175
2176 if (!os::commit_memory(start, len, false)) {
2177 return false;
2178 }
2179
2180 if (AlwaysPreTouch) {
2181 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size);
2182 }
2183
2184 return true;
2185 }
2186
2187 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2188 shenandoah_assert_heaplocked();
2189
2190 // Bitmaps in special regions do not need uncommits
2191 if (_bitmap_region_special) {
2192 return true;
2193 }
2194
2195 if (is_bitmap_slice_committed(r, true)) {
2196 // Some other region from the group is still committed, meaning the bitmap
2197 // slice is should stay committed, exit right away.
2198 return true;
2199 }
2200
2201 // Uncommit the bitmap slice:
2202 size_t slice = r->index() / _bitmap_regions_per_slice;
2203 size_t off = _bitmap_bytes_per_slice * slice;
2204 size_t len = _bitmap_bytes_per_slice;
2205 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2206 return false;
2207 }
2208 return true;
2209 }
2210
2211 void ShenandoahHeap::safepoint_synchronize_begin() {
2212 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2213 SuspendibleThreadSet::synchronize();
2214 }
2215 }
2216
2217 void ShenandoahHeap::safepoint_synchronize_end() {
2218 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2219 SuspendibleThreadSet::desynchronize();
2220 }
2221 }
2222
2223 void ShenandoahHeap::entry_uncommit(double shrink_before, size_t shrink_until) {
2224 static const char *msg = "Concurrent uncommit";
2225 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
2226 EventMark em("%s", msg);
2227
2228 op_uncommit(shrink_before, shrink_until);
2229 }
2230
2231 void ShenandoahHeap::try_inject_alloc_failure() {
2232 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2233 _inject_alloc_failure.set();
2234 os::naked_short_sleep(1);
2235 if (cancelled_gc()) {
2236 log_info(gc)("Allocation failure was successfully injected");
2237 }
2238 }
2239 }
2240
2241 bool ShenandoahHeap::should_inject_alloc_failure() {
2242 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2243 }
2244
2245 void ShenandoahHeap::initialize_serviceability() {
2246 _memory_pool = new ShenandoahMemoryPool(this);
2247 _cycle_memory_manager.add_pool(_memory_pool);
2248 _stw_memory_manager.add_pool(_memory_pool);
2249 }
2250
2251 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2252 GrowableArray<GCMemoryManager*> memory_managers(2);
2253 memory_managers.append(&_cycle_memory_manager);
2254 memory_managers.append(&_stw_memory_manager);
2255 return memory_managers;
2256 }
2257
2258 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2259 GrowableArray<MemoryPool*> memory_pools(1);
2260 memory_pools.append(_memory_pool);
2261 return memory_pools;
2262 }
2263
2264 MemoryUsage ShenandoahHeap::memory_usage() {
2265 return _memory_pool->get_memory_usage();
2266 }
2267
2268 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2269 _heap(ShenandoahHeap::heap()),
2270 _index(0) {}
2271
2272 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2273 _heap(heap),
2274 _index(0) {}
2275
2276 void ShenandoahRegionIterator::reset() {
2277 _index = 0;
2278 }
2279
2280 bool ShenandoahRegionIterator::has_next() const {
2281 return _index < _heap->num_regions();
2282 }
2283
2284 char ShenandoahHeap::gc_state() const {
2285 return _gc_state.raw_value();
2286 }
2287
2288 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2289 #ifdef ASSERT
2290 assert(_liveness_cache != NULL, "sanity");
2291 assert(worker_id < _max_workers, "sanity");
2292 for (uint i = 0; i < num_regions(); i++) {
2293 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2294 }
2295 #endif
2296 return _liveness_cache[worker_id];
2297 }
2298
2299 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2300 assert(worker_id < _max_workers, "sanity");
2301 assert(_liveness_cache != NULL, "sanity");
2302 ShenandoahLiveData* ld = _liveness_cache[worker_id];
2303 for (uint i = 0; i < num_regions(); i++) {
2304 ShenandoahLiveData live = ld[i];
2305 if (live > 0) {
2306 ShenandoahHeapRegion* r = get_region(i);
2307 r->increase_live_data_gc_words(live);
2308 ld[i] = 0;
2309 }
2310 }
2311 }