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 _forwarding = new SlidingForwarding(_heap_region, ShenandoahHeapRegion::region_size_words_shift());
196
197 #if SHENANDOAH_OPTIMIZED_MARKTASK
198 // The optimized ShenandoahMarkTask takes some bits away from the full object bits.
199 // Fail if we ever attempt to address more than we can.
200 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) {
201 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
202 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
203 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
204 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable());
205 vm_exit_during_initialization("Fatal Error", buf);
206 }
207 #endif
208
209 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
210 if (!_heap_region_special) {
211 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
212 "Cannot commit heap memory");
213 }
214
215 //
216 // Reserve and commit memory for bitmap(s)
217 //
218
219 _bitmap_size = ShenandoahMarkBitMap::compute_size(heap_rs.size());
220 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
221
222 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor();
223
224 guarantee(bitmap_bytes_per_region != 0,
225 "Bitmap bytes per region should not be zero");
226 guarantee(is_power_of_2(bitmap_bytes_per_region),
227 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
228
229 if (bitmap_page_size > bitmap_bytes_per_region) {
230 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
231 _bitmap_bytes_per_slice = bitmap_page_size;
232 } else {
233 _bitmap_regions_per_slice = 1;
234 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
235 }
236
237 guarantee(_bitmap_regions_per_slice >= 1,
238 "Should have at least one region per slice: " SIZE_FORMAT,
239 _bitmap_regions_per_slice);
240
241 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
242 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
243 _bitmap_bytes_per_slice, bitmap_page_size);
244
245 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
246 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
247 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
248 _bitmap_region_special = bitmap.special();
249
250 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
251 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
252 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
253 if (!_bitmap_region_special) {
254 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
255 "Cannot commit bitmap memory");
256 }
257
258 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions, _max_workers);
259
260 if (ShenandoahVerify) {
261 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
262 if (!verify_bitmap.special()) {
263 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
264 "Cannot commit verification bitmap memory");
265 }
266 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
267 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
268 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
269 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
270 }
271
272 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
273 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
274 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
275 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
276 _aux_bitmap_region_special = aux_bitmap.special();
277 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
278
279 //
280 // Create regions and region sets
281 //
282 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
283 size_t region_storage_size = align_up(region_align * _num_regions, region_page_size);
284 region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity());
285
286 ReservedSpace region_storage(region_storage_size, region_page_size);
287 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
288 if (!region_storage.special()) {
289 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
290 "Cannot commit region memory");
291 }
292
293 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks.
294 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there.
295 // If not successful, bite a bullet and allocate at whatever address.
296 {
297 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
298 size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align);
299
300 uintptr_t min = round_up_power_of_2(cset_align);
301 uintptr_t max = (1u << 30u);
302
303 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
304 char* req_addr = (char*)addr;
305 assert(is_aligned(req_addr, cset_align), "Should be aligned");
306 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size(), req_addr);
307 if (cset_rs.is_reserved()) {
308 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr);
309 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
310 break;
311 }
312 }
313
314 if (_collection_set == NULL) {
315 ReservedSpace cset_rs(cset_size, cset_align, os::vm_page_size());
316 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
317 }
318 }
319
320 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
321 _free_set = new ShenandoahFreeSet(this, _num_regions);
322
323 {
324 ShenandoahHeapLocker locker(lock());
325
326 for (size_t i = 0; i < _num_regions; i++) {
327 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
328 bool is_committed = i < num_committed_regions;
329 void* loc = region_storage.base() + i * region_align;
330
331 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
332 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
333
334 _marking_context->initialize_top_at_mark_start(r);
335 _regions[i] = r;
336 assert(!collection_set()->is_in(i), "New region should not be in collection set");
337 }
338
339 // Initialize to complete
340 _marking_context->mark_complete();
341
342 _free_set->rebuild();
343 }
344
345 if (AlwaysPreTouch) {
346 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
347 // before initialize() below zeroes it with initializing thread. For any given region,
348 // we touch the region and the corresponding bitmaps from the same thread.
349 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
350
351 _pretouch_heap_page_size = heap_page_size;
352 _pretouch_bitmap_page_size = bitmap_page_size;
353
354 #ifdef LINUX
355 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
356 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
357 // them into huge one. Therefore, we need to pretouch with smaller pages.
358 if (UseTransparentHugePages) {
359 _pretouch_heap_page_size = (size_t)os::vm_page_size();
360 _pretouch_bitmap_page_size = (size_t)os::vm_page_size();
361 }
362 #endif
363
364 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
365 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
366
367 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size);
368 _workers->run_task(&bcl);
369
370 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size);
371 _workers->run_task(&hcl);
372 }
373
374 //
375 // Initialize the rest of GC subsystems
376 //
377
378 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
379 for (uint worker = 0; worker < _max_workers; worker++) {
380 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
381 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
382 }
383
384 // There should probably be Shenandoah-specific options for these,
385 // just as there are G1-specific options.
386 {
387 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
388 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
389 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
390 }
391
392 _monitoring_support = new ShenandoahMonitoringSupport(this);
393 _phase_timings = new ShenandoahPhaseTimings(max_workers());
394 ShenandoahCodeRoots::initialize();
395
396 if (ShenandoahPacing) {
397 _pacer = new ShenandoahPacer(this);
398 _pacer->setup_for_idle();
399 } else {
400 _pacer = NULL;
401 }
402
403 _control_thread = new ShenandoahControlThread();
404
405 ShenandoahInitLogger::print();
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 _control_thread(NULL),
472 _shenandoah_policy(policy),
473 _gc_mode(NULL),
474 _heuristics(NULL),
475 _free_set(NULL),
476 _pacer(NULL),
477 _verifier(NULL),
478 _phase_timings(NULL),
479 _monitoring_support(NULL),
480 _memory_pool(NULL),
481 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
482 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
483 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
484 _soft_ref_policy(),
485 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
486 _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))),
487 _marking_context(NULL),
488 _bitmap_size(0),
489 _bitmap_regions_per_slice(0),
490 _bitmap_bytes_per_slice(0),
491 _bitmap_region_special(false),
492 _aux_bitmap_region_special(false),
493 _liveness_cache(NULL),
494 _collection_set(NULL)
495 {
496 // Initialize GC mode early, so we can adjust barrier support
497 initialize_mode();
498 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
499
500 _max_workers = MAX2(_max_workers, 1U);
501 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
502 /* are_GC_task_threads */ true,
503 /* are_ConcurrentGC_threads */ true);
504 if (_workers == NULL) {
505 vm_exit_during_initialization("Failed necessary allocation.");
506 } else {
507 _workers->initialize_workers();
508 }
509
510 if (ParallelGCThreads > 1) {
511 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
512 ParallelGCThreads,
513 /* are_GC_task_threads */ false,
514 /* are_ConcurrentGC_threads */ false);
515 _safepoint_workers->initialize_workers();
516 }
517 }
518
519 #ifdef _MSC_VER
520 #pragma warning( pop )
521 #endif
522
523 class ShenandoahResetBitmapTask : public AbstractGangTask {
524 private:
525 ShenandoahRegionIterator _regions;
526
527 public:
528 ShenandoahResetBitmapTask() :
529 AbstractGangTask("Shenandoah Reset Bitmap") {}
530
531 void work(uint worker_id) {
532 ShenandoahHeapRegion* region = _regions.next();
533 ShenandoahHeap* heap = ShenandoahHeap::heap();
534 ShenandoahMarkingContext* const ctx = heap->marking_context();
535 while (region != NULL) {
536 if (heap->is_bitmap_slice_committed(region)) {
537 ctx->clear_bitmap(region);
538 }
539 region = _regions.next();
540 }
541 }
542 };
543
544 void ShenandoahHeap::reset_mark_bitmap() {
545 assert_gc_workers(_workers->active_workers());
546 mark_incomplete_marking_context();
547
548 ShenandoahResetBitmapTask task;
549 _workers->run_task(&task);
550 }
551
552 void ShenandoahHeap::print_on(outputStream* st) const {
553 st->print_cr("Shenandoah Heap");
554 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
555 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
556 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
557 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
558 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
559 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
560 num_regions(),
561 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
562 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
563
564 st->print("Status: ");
565 if (has_forwarded_objects()) st->print("has forwarded objects, ");
566 if (is_concurrent_mark_in_progress()) st->print("marking, ");
567 if (is_evacuation_in_progress()) st->print("evacuating, ");
568 if (is_update_refs_in_progress()) st->print("updating refs, ");
569 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
570 if (is_full_gc_in_progress()) st->print("full gc, ");
571 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
572 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
573 if (is_concurrent_strong_root_in_progress() &&
574 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
575
576 if (cancelled_gc()) {
577 st->print("cancelled");
578 } else {
579 st->print("not cancelled");
580 }
581 st->cr();
582
583 st->print_cr("Reserved region:");
584 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
585 p2i(reserved_region().start()),
586 p2i(reserved_region().end()));
587
588 ShenandoahCollectionSet* cset = collection_set();
589 st->print_cr("Collection set:");
590 if (cset != NULL) {
591 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
592 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
593 } else {
594 st->print_cr(" (NULL)");
595 }
596
597 st->cr();
598 MetaspaceUtils::print_on(st);
599
600 if (Verbose) {
601 print_heap_regions_on(st);
602 }
603 }
604
605 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
606 public:
607 void do_thread(Thread* thread) {
608 assert(thread != NULL, "Sanity");
609 assert(thread->is_Worker_thread(), "Only worker thread expected");
610 ShenandoahThreadLocalData::initialize_gclab(thread);
611 }
612 };
613
614 void ShenandoahHeap::post_initialize() {
615 CollectedHeap::post_initialize();
616 MutexLocker ml(Threads_lock);
617
618 ShenandoahInitWorkerGCLABClosure init_gclabs;
619 _workers->threads_do(&init_gclabs);
620
621 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
622 // Now, we will let WorkGang to initialize gclab when new worker is created.
623 _workers->set_initialize_gclab();
624 if (_safepoint_workers != NULL) {
625 _safepoint_workers->threads_do(&init_gclabs);
626 _safepoint_workers->set_initialize_gclab();
627 }
628
629 _heuristics->initialize();
630
631 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
632 }
633
634 size_t ShenandoahHeap::used() const {
635 return Atomic::load(&_used);
636 }
637
638 size_t ShenandoahHeap::committed() const {
639 return Atomic::load(&_committed);
640 }
641
642 void ShenandoahHeap::increase_committed(size_t bytes) {
643 shenandoah_assert_heaplocked_or_safepoint();
644 _committed += bytes;
645 }
646
647 void ShenandoahHeap::decrease_committed(size_t bytes) {
648 shenandoah_assert_heaplocked_or_safepoint();
649 _committed -= bytes;
650 }
651
652 void ShenandoahHeap::increase_used(size_t bytes) {
653 Atomic::add(&_used, bytes, memory_order_relaxed);
654 }
655
656 void ShenandoahHeap::set_used(size_t bytes) {
657 Atomic::store(&_used, bytes);
658 }
659
660 void ShenandoahHeap::decrease_used(size_t bytes) {
661 assert(used() >= bytes, "never decrease heap size by more than we've left");
662 Atomic::sub(&_used, bytes, memory_order_relaxed);
663 }
664
665 void ShenandoahHeap::increase_allocated(size_t bytes) {
666 Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed);
667 }
668
669 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
670 size_t bytes = words * HeapWordSize;
671 if (!waste) {
672 increase_used(bytes);
673 }
674 increase_allocated(bytes);
675 if (ShenandoahPacing) {
676 control_thread()->pacing_notify_alloc(words);
677 if (waste) {
678 pacer()->claim_for_alloc(words, true);
679 }
680 }
681 }
682
683 size_t ShenandoahHeap::capacity() const {
684 return committed();
685 }
686
687 size_t ShenandoahHeap::max_capacity() const {
688 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
689 }
690
691 size_t ShenandoahHeap::soft_max_capacity() const {
692 size_t v = Atomic::load(&_soft_max_size);
693 assert(min_capacity() <= v && v <= max_capacity(),
694 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
695 min_capacity(), v, max_capacity());
696 return v;
697 }
698
699 void ShenandoahHeap::set_soft_max_capacity(size_t v) {
700 assert(min_capacity() <= v && v <= max_capacity(),
701 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
702 min_capacity(), v, max_capacity());
703 Atomic::store(&_soft_max_size, v);
704 }
705
706 size_t ShenandoahHeap::min_capacity() const {
707 return _minimum_size;
708 }
709
710 size_t ShenandoahHeap::initial_capacity() const {
711 return _initial_size;
712 }
713
714 bool ShenandoahHeap::is_in(const void* p) const {
715 HeapWord* heap_base = (HeapWord*) base();
716 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
717 return p >= heap_base && p < last_region_end;
718 }
719
720 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
721 assert (ShenandoahUncommit, "should be enabled");
722
723 // Application allocates from the beginning of the heap, and GC allocates at
724 // the end of it. It is more efficient to uncommit from the end, so that applications
725 // could enjoy the near committed regions. GC allocations are much less frequent,
726 // and therefore can accept the committing costs.
727
728 size_t count = 0;
729 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
730 ShenandoahHeapRegion* r = get_region(i - 1);
731 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
732 ShenandoahHeapLocker locker(lock());
733 if (r->is_empty_committed()) {
734 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
735 break;
736 }
737
738 r->make_uncommitted();
739 count++;
740 }
741 }
742 SpinPause(); // allow allocators to take the lock
743 }
744
745 if (count > 0) {
746 control_thread()->notify_heap_changed();
747 }
748 }
749
750 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
751 // New object should fit the GCLAB size
752 size_t min_size = MAX2(size, PLAB::min_size());
753
754 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
755 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
756 new_size = MIN2(new_size, PLAB::max_size());
757 new_size = MAX2(new_size, PLAB::min_size());
758
759 // Record new heuristic value even if we take any shortcut. This captures
760 // the case when moderately-sized objects always take a shortcut. At some point,
761 // heuristics should catch up with them.
762 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
763
764 if (new_size < size) {
765 // New size still does not fit the object. Fall back to shared allocation.
766 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
767 return NULL;
768 }
769
770 // Retire current GCLAB, and allocate a new one.
771 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
772 gclab->retire();
773
774 size_t actual_size = 0;
775 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
776 if (gclab_buf == NULL) {
777 return NULL;
778 }
779
780 assert (size <= actual_size, "allocation should fit");
781
782 if (ZeroTLAB) {
783 // ..and clear it.
784 Copy::zero_to_words(gclab_buf, actual_size);
785 } else {
786 // ...and zap just allocated object.
787 #ifdef ASSERT
788 // Skip mangling the space corresponding to the object header to
789 // ensure that the returned space is not considered parsable by
790 // any concurrent GC thread.
791 size_t hdr_size = oopDesc::header_size();
792 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
793 #endif // ASSERT
794 }
795 gclab->set_buf(gclab_buf, actual_size);
796 return gclab->allocate(size);
797 }
798
799 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
800 size_t requested_size,
801 size_t* actual_size) {
802 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
803 HeapWord* res = allocate_memory(req);
804 if (res != NULL) {
805 *actual_size = req.actual_size();
806 } else {
807 *actual_size = 0;
808 }
809 return res;
810 }
811
812 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
813 size_t word_size,
814 size_t* actual_size) {
815 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
816 HeapWord* res = allocate_memory(req);
817 if (res != NULL) {
818 *actual_size = req.actual_size();
819 } else {
820 *actual_size = 0;
821 }
822 return res;
823 }
824
825 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
826 intptr_t pacer_epoch = 0;
827 bool in_new_region = false;
828 HeapWord* result = NULL;
829
830 if (req.is_mutator_alloc()) {
831 if (ShenandoahPacing) {
832 pacer()->pace_for_alloc(req.size());
833 pacer_epoch = pacer()->epoch();
834 }
835
836 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
837 result = allocate_memory_under_lock(req, in_new_region);
838 }
839
840 // Allocation failed, block until control thread reacted, then retry allocation.
841 //
842 // It might happen that one of the threads requesting allocation would unblock
843 // way later after GC happened, only to fail the second allocation, because
844 // other threads have already depleted the free storage. In this case, a better
845 // strategy is to try again, as long as GC makes progress.
846 //
847 // Then, we need to make sure the allocation was retried after at least one
848 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
849
850 size_t tries = 0;
851
852 while (result == NULL && _progress_last_gc.is_set()) {
853 tries++;
854 control_thread()->handle_alloc_failure(req);
855 result = allocate_memory_under_lock(req, in_new_region);
856 }
857
858 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
859 tries++;
860 control_thread()->handle_alloc_failure(req);
861 result = allocate_memory_under_lock(req, in_new_region);
862 }
863
864 } else {
865 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
866 result = allocate_memory_under_lock(req, in_new_region);
867 // Do not call handle_alloc_failure() here, because we cannot block.
868 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
869 }
870
871 if (in_new_region) {
872 control_thread()->notify_heap_changed();
873 }
874
875 if (result != NULL) {
876 size_t requested = req.size();
877 size_t actual = req.actual_size();
878
879 assert (req.is_lab_alloc() || (requested == actual),
880 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
881 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
882
883 if (req.is_mutator_alloc()) {
884 notify_mutator_alloc_words(actual, false);
885
886 // If we requested more than we were granted, give the rest back to pacer.
887 // This only matters if we are in the same pacing epoch: do not try to unpace
888 // over the budget for the other phase.
889 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
890 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
891 }
892 } else {
893 increase_used(actual*HeapWordSize);
894 }
895 }
896
897 return result;
898 }
899
900 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
901 ShenandoahHeapLocker locker(lock());
902 return _free_set->allocate(req, in_new_region);
903 }
904
905 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
906 bool* gc_overhead_limit_was_exceeded) {
907 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
908 return allocate_memory(req);
909 }
910
911 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
912 size_t size,
913 Metaspace::MetadataType mdtype) {
914 MetaWord* result;
915
916 // Inform metaspace OOM to GC heuristics if class unloading is possible.
917 if (heuristics()->can_unload_classes()) {
918 ShenandoahHeuristics* h = heuristics();
919 h->record_metaspace_oom();
920 }
921
922 // Expand and retry allocation
923 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
924 if (result != NULL) {
925 return result;
926 }
927
928 // Start full GC
929 collect(GCCause::_metadata_GC_clear_soft_refs);
930
931 // Retry allocation
932 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
933 if (result != NULL) {
934 return result;
935 }
936
937 // Expand and retry allocation
938 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
939 if (result != NULL) {
940 return result;
941 }
942
943 // Out of memory
944 return NULL;
945 }
946
947 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
948 private:
949 ShenandoahHeap* const _heap;
950 Thread* const _thread;
951 public:
952 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
953 _heap(heap), _thread(Thread::current()) {}
954
955 void do_object(oop p) {
956 shenandoah_assert_marked(NULL, p);
957 if (!ShenandoahForwarding::is_forwarded(p)) {
958 _heap->evacuate_object(p, _thread);
959 }
960 }
961 };
962
963 class ShenandoahEvacuationTask : public AbstractGangTask {
964 private:
965 ShenandoahHeap* const _sh;
966 ShenandoahCollectionSet* const _cs;
967 bool _concurrent;
968 public:
969 ShenandoahEvacuationTask(ShenandoahHeap* sh,
970 ShenandoahCollectionSet* cs,
971 bool concurrent) :
972 AbstractGangTask("Shenandoah Evacuation"),
973 _sh(sh),
974 _cs(cs),
975 _concurrent(concurrent)
976 {}
977
978 void work(uint worker_id) {
979 if (_concurrent) {
980 ShenandoahConcurrentWorkerSession worker_session(worker_id);
981 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
982 ShenandoahEvacOOMScope oom_evac_scope;
983 do_work();
984 } else {
985 ShenandoahParallelWorkerSession worker_session(worker_id);
986 ShenandoahEvacOOMScope oom_evac_scope;
987 do_work();
988 }
989 }
990
991 private:
992 void do_work() {
993 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
994 ShenandoahHeapRegion* r;
995 while ((r =_cs->claim_next()) != NULL) {
996 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
997 _sh->marked_object_iterate(r, &cl);
998
999 if (ShenandoahPacing) {
1000 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
1001 }
1002
1003 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1004 break;
1005 }
1006 }
1007 }
1008 };
1009
1010 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
1011 ShenandoahEvacuationTask task(this, _collection_set, concurrent);
1012 workers()->run_task(&task);
1013 }
1014
1015 void ShenandoahHeap::trash_cset_regions() {
1016 ShenandoahHeapLocker locker(lock());
1017
1018 ShenandoahCollectionSet* set = collection_set();
1019 ShenandoahHeapRegion* r;
1020 set->clear_current_index();
1021 while ((r = set->next()) != NULL) {
1022 r->make_trash();
1023 }
1024 collection_set()->clear();
1025 }
1026
1027 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1028 st->print_cr("Heap Regions:");
1029 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
1030 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
1031 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark");
1032 st->print_cr("SN=alloc sequence number");
1033
1034 for (size_t i = 0; i < num_regions(); i++) {
1035 get_region(i)->print_on(st);
1036 }
1037 }
1038
1039 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1040 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1041
1042 oop humongous_obj = cast_to_oop(start->bottom());
1043 size_t size = humongous_obj->size();
1044 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1045 size_t index = start->index() + required_regions - 1;
1046
1047 assert(!start->has_live(), "liveness must be zero");
1048
1049 for(size_t i = 0; i < required_regions; i++) {
1050 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1051 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1052 ShenandoahHeapRegion* region = get_region(index --);
1053
1054 assert(region->is_humongous(), "expect correct humongous start or continuation");
1055 assert(!region->is_cset(), "Humongous region should not be in collection set");
1056
1057 region->make_trash_immediate();
1058 }
1059 }
1060
1061 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1062 public:
1063 ShenandoahCheckCleanGCLABClosure() {}
1064 void do_thread(Thread* thread) {
1065 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1066 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1067 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1068 }
1069 };
1070
1071 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1072 private:
1073 bool const _resize;
1074 public:
1075 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1076 void do_thread(Thread* thread) {
1077 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1078 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1079 gclab->retire();
1080 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1081 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1082 }
1083 }
1084 };
1085
1086 void ShenandoahHeap::labs_make_parsable() {
1087 assert(UseTLAB, "Only call with UseTLAB");
1088
1089 ShenandoahRetireGCLABClosure cl(false);
1090
1091 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1092 ThreadLocalAllocBuffer& tlab = t->tlab();
1093 tlab.make_parsable();
1094 cl.do_thread(t);
1095 }
1096
1097 workers()->threads_do(&cl);
1098 }
1099
1100 void ShenandoahHeap::tlabs_retire(bool resize) {
1101 assert(UseTLAB, "Only call with UseTLAB");
1102 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1103
1104 ThreadLocalAllocStats stats;
1105
1106 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1107 ThreadLocalAllocBuffer& tlab = t->tlab();
1108 tlab.retire(&stats);
1109 if (resize) {
1110 tlab.resize();
1111 }
1112 }
1113
1114 stats.publish();
1115
1116 #ifdef ASSERT
1117 ShenandoahCheckCleanGCLABClosure cl;
1118 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1119 cl.do_thread(t);
1120 }
1121 workers()->threads_do(&cl);
1122 #endif
1123 }
1124
1125 void ShenandoahHeap::gclabs_retire(bool resize) {
1126 assert(UseTLAB, "Only call with UseTLAB");
1127 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1128
1129 ShenandoahRetireGCLABClosure cl(resize);
1130 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1131 cl.do_thread(t);
1132 }
1133 workers()->threads_do(&cl);
1134
1135 if (safepoint_workers() != NULL) {
1136 safepoint_workers()->threads_do(&cl);
1137 }
1138 }
1139
1140 // Returns size in bytes
1141 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1142 if (ShenandoahElasticTLAB) {
1143 // With Elastic TLABs, return the max allowed size, and let the allocation path
1144 // figure out the safe size for current allocation.
1145 return ShenandoahHeapRegion::max_tlab_size_bytes();
1146 } else {
1147 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1148 }
1149 }
1150
1151 size_t ShenandoahHeap::max_tlab_size() const {
1152 // Returns size in words
1153 return ShenandoahHeapRegion::max_tlab_size_words();
1154 }
1155
1156 void ShenandoahHeap::collect(GCCause::Cause cause) {
1157 control_thread()->request_gc(cause);
1158 }
1159
1160 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1161 //assert(false, "Shouldn't need to do full collections");
1162 }
1163
1164 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1165 ShenandoahHeapRegion* r = heap_region_containing(addr);
1166 if (r != NULL) {
1167 return r->block_start(addr);
1168 }
1169 return NULL;
1170 }
1171
1172 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1173 ShenandoahHeapRegion* r = heap_region_containing(addr);
1174 return r->block_is_obj(addr);
1175 }
1176
1177 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1178 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1179 }
1180
1181 void ShenandoahHeap::prepare_for_verify() {
1182 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1183 labs_make_parsable();
1184 }
1185 }
1186
1187 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1188 workers()->threads_do(tcl);
1189 if (_safepoint_workers != NULL) {
1190 _safepoint_workers->threads_do(tcl);
1191 }
1192 if (ShenandoahStringDedup::is_enabled()) {
1193 ShenandoahStringDedup::threads_do(tcl);
1194 }
1195 }
1196
1197 void ShenandoahHeap::print_tracing_info() const {
1198 LogTarget(Info, gc, stats) lt;
1199 if (lt.is_enabled()) {
1200 ResourceMark rm;
1201 LogStream ls(lt);
1202
1203 phase_timings()->print_global_on(&ls);
1204
1205 ls.cr();
1206 ls.cr();
1207
1208 shenandoah_policy()->print_gc_stats(&ls);
1209
1210 ls.cr();
1211 ls.cr();
1212 }
1213 }
1214
1215 void ShenandoahHeap::verify(VerifyOption vo) {
1216 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1217 if (ShenandoahVerify) {
1218 verifier()->verify_generic(vo);
1219 } else {
1220 // TODO: Consider allocating verification bitmaps on demand,
1221 // and turn this on unconditionally.
1222 }
1223 }
1224 }
1225 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1226 return _free_set->capacity();
1227 }
1228
1229 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1230 private:
1231 MarkBitMap* _bitmap;
1232 ShenandoahScanObjectStack* _oop_stack;
1233 ShenandoahHeap* const _heap;
1234 ShenandoahMarkingContext* const _marking_context;
1235
1236 template <class T>
1237 void do_oop_work(T* p) {
1238 T o = RawAccess<>::oop_load(p);
1239 if (!CompressedOops::is_null(o)) {
1240 oop obj = CompressedOops::decode_not_null(o);
1241 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1242 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1243 return;
1244 }
1245 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1246
1247 assert(oopDesc::is_oop(obj), "must be a valid oop");
1248 if (!_bitmap->is_marked(obj)) {
1249 _bitmap->mark(obj);
1250 _oop_stack->push(obj);
1251 }
1252 }
1253 }
1254 public:
1255 ObjectIterateScanRootClosure(MarkBitMap* bitmap, ShenandoahScanObjectStack* oop_stack) :
1256 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1257 _marking_context(_heap->marking_context()) {}
1258 void do_oop(oop* p) { do_oop_work(p); }
1259 void do_oop(narrowOop* p) { do_oop_work(p); }
1260 };
1261
1262 /*
1263 * This is public API, used in preparation of object_iterate().
1264 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1265 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1266 * control, we call SH::tlabs_retire, SH::gclabs_retire.
1267 */
1268 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1269 // No-op.
1270 }
1271
1272 /*
1273 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1274 *
1275 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1276 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1277 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1278 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1279 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1280 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1281 * wiped the bitmap in preparation for next marking).
1282 *
1283 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1284 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1285 * is allowed to report dead objects, but is not required to do so.
1286 */
1287 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1288 // Reset bitmap
1289 if (!prepare_aux_bitmap_for_iteration())
1290 return;
1291
1292 ShenandoahScanObjectStack oop_stack;
1293 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1294 // Seed the stack with root scan
1295 scan_roots_for_iteration(&oop_stack, &oops);
1296
1297 // Work through the oop stack to traverse heap
1298 while (! oop_stack.is_empty()) {
1299 oop obj = oop_stack.pop();
1300 assert(oopDesc::is_oop(obj), "must be a valid oop");
1301 shenandoah_assert_not_in_cset_except(NULL, obj, cancelled_gc());
1302 cl->do_object(obj);
1303 obj->oop_iterate(&oops);
1304 }
1305
1306 assert(oop_stack.is_empty(), "should be empty");
1307 // Reclaim bitmap
1308 reclaim_aux_bitmap_for_iteration();
1309 }
1310
1311 bool ShenandoahHeap::prepare_aux_bitmap_for_iteration() {
1312 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1313
1314 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1315 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1316 return false;
1317 }
1318 // Reset bitmap
1319 _aux_bit_map.clear();
1320 return true;
1321 }
1322
1323 void ShenandoahHeap::scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops) {
1324 // Process GC roots according to current GC cycle
1325 // This populates the work stack with initial objects
1326 // It is important to relinquish the associated locks before diving
1327 // into heap dumper
1328 ShenandoahHeapIterationRootScanner rp;
1329 rp.roots_do(oops);
1330 }
1331
1332 void ShenandoahHeap::reclaim_aux_bitmap_for_iteration() {
1333 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1334 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1335 }
1336 }
1337
1338 // Closure for parallelly iterate objects
1339 class ShenandoahObjectIterateParScanClosure : public BasicOopIterateClosure {
1340 private:
1341 MarkBitMap* _bitmap;
1342 ShenandoahObjToScanQueue* _queue;
1343 ShenandoahHeap* const _heap;
1344 ShenandoahMarkingContext* const _marking_context;
1345
1346 template <class T>
1347 void do_oop_work(T* p) {
1348 T o = RawAccess<>::oop_load(p);
1349 if (!CompressedOops::is_null(o)) {
1350 oop obj = CompressedOops::decode_not_null(o);
1351 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1352 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1353 return;
1354 }
1355 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1356
1357 assert(oopDesc::is_oop(obj), "Must be a valid oop");
1358 if (_bitmap->par_mark(obj)) {
1359 _queue->push(ShenandoahMarkTask(obj));
1360 }
1361 }
1362 }
1363 public:
1364 ShenandoahObjectIterateParScanClosure(MarkBitMap* bitmap, ShenandoahObjToScanQueue* q) :
1365 _bitmap(bitmap), _queue(q), _heap(ShenandoahHeap::heap()),
1366 _marking_context(_heap->marking_context()) {}
1367 void do_oop(oop* p) { do_oop_work(p); }
1368 void do_oop(narrowOop* p) { do_oop_work(p); }
1369 };
1370
1371 // Object iterator for parallel heap iteraion.
1372 // The root scanning phase happenes in construction as a preparation of
1373 // parallel marking queues.
1374 // Every worker processes it's own marking queue. work-stealing is used
1375 // to balance workload.
1376 class ShenandoahParallelObjectIterator : public ParallelObjectIterator {
1377 private:
1378 uint _num_workers;
1379 bool _init_ready;
1380 MarkBitMap* _aux_bit_map;
1381 ShenandoahHeap* _heap;
1382 ShenandoahScanObjectStack _roots_stack; // global roots stack
1383 ShenandoahObjToScanQueueSet* _task_queues;
1384 public:
1385 ShenandoahParallelObjectIterator(uint num_workers, MarkBitMap* bitmap) :
1386 _num_workers(num_workers),
1387 _init_ready(false),
1388 _aux_bit_map(bitmap),
1389 _heap(ShenandoahHeap::heap()) {
1390 // Initialize bitmap
1391 _init_ready = _heap->prepare_aux_bitmap_for_iteration();
1392 if (!_init_ready) {
1393 return;
1394 }
1395
1396 ObjectIterateScanRootClosure oops(_aux_bit_map, &_roots_stack);
1397 _heap->scan_roots_for_iteration(&_roots_stack, &oops);
1398
1399 _init_ready = prepare_worker_queues();
1400 }
1401
1402 ~ShenandoahParallelObjectIterator() {
1403 // Reclaim bitmap
1404 _heap->reclaim_aux_bitmap_for_iteration();
1405 // Reclaim queue for workers
1406 if (_task_queues!= NULL) {
1407 for (uint i = 0; i < _num_workers; ++i) {
1408 ShenandoahObjToScanQueue* q = _task_queues->queue(i);
1409 if (q != NULL) {
1410 delete q;
1411 _task_queues->register_queue(i, NULL);
1412 }
1413 }
1414 delete _task_queues;
1415 _task_queues = NULL;
1416 }
1417 }
1418
1419 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
1420 if (_init_ready) {
1421 object_iterate_parallel(cl, worker_id, _task_queues);
1422 }
1423 }
1424
1425 private:
1426 // Divide global root_stack into worker queues
1427 bool prepare_worker_queues() {
1428 _task_queues = new ShenandoahObjToScanQueueSet((int) _num_workers);
1429 // Initialize queues for every workers
1430 for (uint i = 0; i < _num_workers; ++i) {
1431 ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue();
1432 task_queue->initialize();
1433 _task_queues->register_queue(i, task_queue);
1434 }
1435 // Divide roots among the workers. Assume that object referencing distribution
1436 // is related with root kind, use round-robin to make every worker have same chance
1437 // to process every kind of roots
1438 size_t roots_num = _roots_stack.size();
1439 if (roots_num == 0) {
1440 // No work to do
1441 return false;
1442 }
1443
1444 for (uint j = 0; j < roots_num; j++) {
1445 uint stack_id = j % _num_workers;
1446 oop obj = _roots_stack.pop();
1447 _task_queues->queue(stack_id)->push(ShenandoahMarkTask(obj));
1448 }
1449 return true;
1450 }
1451
1452 void object_iterate_parallel(ObjectClosure* cl,
1453 uint worker_id,
1454 ShenandoahObjToScanQueueSet* queue_set) {
1455 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1456 assert(queue_set != NULL, "task queue must not be NULL");
1457
1458 ShenandoahObjToScanQueue* q = queue_set->queue(worker_id);
1459 assert(q != NULL, "object iterate queue must not be NULL");
1460
1461 ShenandoahMarkTask t;
1462 ShenandoahObjectIterateParScanClosure oops(_aux_bit_map, q);
1463
1464 // Work through the queue to traverse heap.
1465 // Steal when there is no task in queue.
1466 while (q->pop(t) || queue_set->steal(worker_id, t)) {
1467 oop obj = t.obj();
1468 assert(oopDesc::is_oop(obj), "must be a valid oop");
1469 cl->do_object(obj);
1470 obj->oop_iterate(&oops);
1471 }
1472 assert(q->is_empty(), "should be empty");
1473 }
1474 };
1475
1476 ParallelObjectIterator* ShenandoahHeap::parallel_object_iterator(uint workers) {
1477 return new ShenandoahParallelObjectIterator(workers, &_aux_bit_map);
1478 }
1479
1480 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1481 void ShenandoahHeap::keep_alive(oop obj) {
1482 if (is_concurrent_mark_in_progress() && (obj != NULL)) {
1483 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1484 }
1485 }
1486
1487 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1488 for (size_t i = 0; i < num_regions(); i++) {
1489 ShenandoahHeapRegion* current = get_region(i);
1490 blk->heap_region_do(current);
1491 }
1492 }
1493
1494 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1495 private:
1496 ShenandoahHeap* const _heap;
1497 ShenandoahHeapRegionClosure* const _blk;
1498
1499 shenandoah_padding(0);
1500 volatile size_t _index;
1501 shenandoah_padding(1);
1502
1503 public:
1504 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1505 AbstractGangTask("Shenandoah Parallel Region Operation"),
1506 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1507
1508 void work(uint worker_id) {
1509 ShenandoahParallelWorkerSession worker_session(worker_id);
1510 size_t stride = ShenandoahParallelRegionStride;
1511
1512 size_t max = _heap->num_regions();
1513 while (Atomic::load(&_index) < max) {
1514 size_t cur = Atomic::fetch_and_add(&_index, stride, memory_order_relaxed);
1515 size_t start = cur;
1516 size_t end = MIN2(cur + stride, max);
1517 if (start >= max) break;
1518
1519 for (size_t i = cur; i < end; i++) {
1520 ShenandoahHeapRegion* current = _heap->get_region(i);
1521 _blk->heap_region_do(current);
1522 }
1523 }
1524 }
1525 };
1526
1527 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1528 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1529 if (num_regions() > ShenandoahParallelRegionStride) {
1530 ShenandoahParallelHeapRegionTask task(blk);
1531 workers()->run_task(&task);
1532 } else {
1533 heap_region_iterate(blk);
1534 }
1535 }
1536
1537 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1538 private:
1539 ShenandoahMarkingContext* const _ctx;
1540 public:
1541 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1542
1543 void heap_region_do(ShenandoahHeapRegion* r) {
1544 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1545 if (r->is_active()) {
1546 // Check if region needs updating its TAMS. We have updated it already during concurrent
1547 // reset, so it is very likely we don't need to do another write here.
1548 if (_ctx->top_at_mark_start(r) != r->top()) {
1549 _ctx->capture_top_at_mark_start(r);
1550 }
1551 } else {
1552 assert(_ctx->top_at_mark_start(r) == r->top(),
1553 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1554 }
1555 }
1556
1557 bool is_thread_safe() { return true; }
1558 };
1559
1560 class ShenandoahRendezvousClosure : public HandshakeClosure {
1561 public:
1562 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
1563 inline void do_thread(Thread* thread) {}
1564 };
1565
1566 void ShenandoahHeap::rendezvous_threads() {
1567 ShenandoahRendezvousClosure cl;
1568 Handshake::execute(&cl);
1569 }
1570
1571 void ShenandoahHeap::recycle_trash() {
1572 free_set()->recycle_trash();
1573 }
1574
1575 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1576 private:
1577 ShenandoahMarkingContext* const _ctx;
1578 public:
1579 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1580
1581 void heap_region_do(ShenandoahHeapRegion* r) {
1582 if (r->is_active()) {
1583 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1584 // anyway to capture any updates that happened since now.
1585 r->clear_live_data();
1586 _ctx->capture_top_at_mark_start(r);
1587 }
1588 }
1589
1590 bool is_thread_safe() { return true; }
1591 };
1592
1593 void ShenandoahHeap::prepare_gc() {
1594 reset_mark_bitmap();
1595
1596 ShenandoahResetUpdateRegionStateClosure cl;
1597 parallel_heap_region_iterate(&cl);
1598 }
1599
1600 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1601 private:
1602 ShenandoahMarkingContext* const _ctx;
1603 ShenandoahHeapLock* const _lock;
1604
1605 public:
1606 ShenandoahFinalMarkUpdateRegionStateClosure() :
1607 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1608
1609 void heap_region_do(ShenandoahHeapRegion* r) {
1610 if (r->is_active()) {
1611 // All allocations past TAMS are implicitly live, adjust the region data.
1612 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1613 HeapWord *tams = _ctx->top_at_mark_start(r);
1614 HeapWord *top = r->top();
1615 if (top > tams) {
1616 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1617 }
1618
1619 // We are about to select the collection set, make sure it knows about
1620 // current pinning status. Also, this allows trashing more regions that
1621 // now have their pinning status dropped.
1622 if (r->is_pinned()) {
1623 if (r->pin_count() == 0) {
1624 ShenandoahHeapLocker locker(_lock);
1625 r->make_unpinned();
1626 }
1627 } else {
1628 if (r->pin_count() > 0) {
1629 ShenandoahHeapLocker locker(_lock);
1630 r->make_pinned();
1631 }
1632 }
1633
1634 // Remember limit for updating refs. It's guaranteed that we get no
1635 // from-space-refs written from here on.
1636 r->set_update_watermark_at_safepoint(r->top());
1637 } else {
1638 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1639 assert(_ctx->top_at_mark_start(r) == r->top(),
1640 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1641 }
1642 }
1643
1644 bool is_thread_safe() { return true; }
1645 };
1646
1647 void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) {
1648 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
1649 {
1650 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states :
1651 ShenandoahPhaseTimings::degen_gc_final_update_region_states);
1652 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1653 parallel_heap_region_iterate(&cl);
1654
1655 assert_pinned_region_status();
1656 }
1657
1658 {
1659 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset :
1660 ShenandoahPhaseTimings::degen_gc_choose_cset);
1661 ShenandoahHeapLocker locker(lock());
1662 _collection_set->clear();
1663 heuristics()->choose_collection_set(_collection_set);
1664 }
1665
1666 {
1667 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset :
1668 ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset);
1669 ShenandoahHeapLocker locker(lock());
1670 _free_set->rebuild();
1671 }
1672 }
1673
1674 void ShenandoahHeap::do_class_unloading() {
1675 _unloader.unload();
1676 }
1677
1678 void ShenandoahHeap::stw_weak_refs(bool full_gc) {
1679 // Weak refs processing
1680 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
1681 : ShenandoahPhaseTimings::degen_gc_weakrefs;
1682 ShenandoahTimingsTracker t(phase);
1683 ShenandoahGCWorkerPhase worker_phase(phase);
1684 ref_processor()->process_references(phase, workers(), false /* concurrent */);
1685 }
1686
1687 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
1688 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1689
1690 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
1691 // make them parsable for update code to work correctly. Plus, we can compute new sizes
1692 // for future GCLABs here.
1693 if (UseTLAB) {
1694 ShenandoahGCPhase phase(concurrent ?
1695 ShenandoahPhaseTimings::init_update_refs_manage_gclabs :
1696 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs);
1697 gclabs_retire(ResizeTLAB);
1698 }
1699
1700 _update_refs_iterator.reset();
1701 }
1702
1703 void ShenandoahHeap::set_gc_state_all_threads(char state) {
1704 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1705 ShenandoahThreadLocalData::set_gc_state(t, state);
1706 }
1707 }
1708
1709 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1710 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1711 _gc_state.set_cond(mask, value);
1712 set_gc_state_all_threads(_gc_state.raw_value());
1713 }
1714
1715 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1716 assert(!has_forwarded_objects(), "Not expected before/after mark phase");
1717 set_gc_state_mask(MARKING, in_progress);
1718 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1719 }
1720
1721 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1722 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1723 set_gc_state_mask(EVACUATION, in_progress);
1724 }
1725
1726 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
1727 if (in_progress) {
1728 _concurrent_strong_root_in_progress.set();
1729 } else {
1730 _concurrent_strong_root_in_progress.unset();
1731 }
1732 }
1733
1734 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) {
1735 set_gc_state_mask(WEAK_ROOTS, cond);
1736 }
1737
1738 GCTracer* ShenandoahHeap::tracer() {
1739 return shenandoah_policy()->tracer();
1740 }
1741
1742 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1743 return _free_set->used();
1744 }
1745
1746 bool ShenandoahHeap::try_cancel_gc() {
1747 while (true) {
1748 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1749 if (prev == CANCELLABLE) return true;
1750 else if (prev == CANCELLED) return false;
1751 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
1752 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
1753 Thread* thread = Thread::current();
1754 if (thread->is_Java_thread()) {
1755 // We need to provide a safepoint here, otherwise we might
1756 // spin forever if a SP is pending.
1757 ThreadBlockInVM sp(thread->as_Java_thread());
1758 SpinPause();
1759 }
1760 }
1761 }
1762
1763 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1764 if (try_cancel_gc()) {
1765 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1766 log_info(gc)("%s", msg.buffer());
1767 Events::log(Thread::current(), "%s", msg.buffer());
1768 }
1769 }
1770
1771 uint ShenandoahHeap::max_workers() {
1772 return _max_workers;
1773 }
1774
1775 void ShenandoahHeap::stop() {
1776 // The shutdown sequence should be able to terminate when GC is running.
1777
1778 // Step 0. Notify policy to disable event recording.
1779 _shenandoah_policy->record_shutdown();
1780
1781 // Step 1. Notify control thread that we are in shutdown.
1782 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1783 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1784 control_thread()->prepare_for_graceful_shutdown();
1785
1786 // Step 2. Notify GC workers that we are cancelling GC.
1787 cancel_gc(GCCause::_shenandoah_stop_vm);
1788
1789 // Step 3. Wait until GC worker exits normally.
1790 control_thread()->stop();
1791 }
1792
1793 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
1794 if (!unload_classes()) return;
1795 // Unload classes and purge SystemDictionary.
1796 {
1797 ShenandoahPhaseTimings::Phase phase = full_gc ?
1798 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1799 ShenandoahPhaseTimings::degen_gc_purge_class_unload;
1800 ShenandoahGCPhase gc_phase(phase);
1801 ShenandoahGCWorkerPhase worker_phase(phase);
1802 bool purged_class = SystemDictionary::do_unloading(gc_timer());
1803
1804 ShenandoahIsAliveSelector is_alive;
1805 uint num_workers = _workers->active_workers();
1806 ShenandoahClassUnloadingTask unlink_task(phase, is_alive.is_alive_closure(), num_workers, purged_class);
1807 _workers->run_task(&unlink_task);
1808 }
1809
1810 {
1811 ShenandoahGCPhase phase(full_gc ?
1812 ShenandoahPhaseTimings::full_gc_purge_cldg :
1813 ShenandoahPhaseTimings::degen_gc_purge_cldg);
1814 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
1815 }
1816 // Resize and verify metaspace
1817 MetaspaceGC::compute_new_size();
1818 DEBUG_ONLY(MetaspaceUtils::verify();)
1819 }
1820
1821 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
1822 // so they should not have forwarded oops.
1823 // However, we do need to "null" dead oops in the roots, if can not be done
1824 // in concurrent cycles.
1825 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
1826 uint num_workers = _workers->active_workers();
1827 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
1828 ShenandoahPhaseTimings::full_gc_purge_weak_par :
1829 ShenandoahPhaseTimings::degen_gc_purge_weak_par;
1830 ShenandoahGCPhase phase(timing_phase);
1831 ShenandoahGCWorkerPhase worker_phase(timing_phase);
1832 // Cleanup weak roots
1833 if (has_forwarded_objects()) {
1834 ShenandoahForwardedIsAliveClosure is_alive;
1835 ShenandoahUpdateRefsClosure keep_alive;
1836 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
1837 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers);
1838 _workers->run_task(&cleaning_task);
1839 } else {
1840 ShenandoahIsAliveClosure is_alive;
1841 #ifdef ASSERT
1842 ShenandoahAssertNotForwardedClosure verify_cl;
1843 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
1844 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers);
1845 #else
1846 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
1847 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers);
1848 #endif
1849 _workers->run_task(&cleaning_task);
1850 }
1851 }
1852
1853 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
1854 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1855 assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC");
1856 ShenandoahGCPhase phase(full_gc ?
1857 ShenandoahPhaseTimings::full_gc_purge :
1858 ShenandoahPhaseTimings::degen_gc_purge);
1859 stw_weak_refs(full_gc);
1860 stw_process_weak_roots(full_gc);
1861 stw_unload_classes(full_gc);
1862 }
1863
1864 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
1865 set_gc_state_mask(HAS_FORWARDED, cond);
1866 }
1867
1868 void ShenandoahHeap::set_unload_classes(bool uc) {
1869 _unload_classes.set_cond(uc);
1870 }
1871
1872 bool ShenandoahHeap::unload_classes() const {
1873 return _unload_classes.is_set();
1874 }
1875
1876 address ShenandoahHeap::in_cset_fast_test_addr() {
1877 ShenandoahHeap* heap = ShenandoahHeap::heap();
1878 assert(heap->collection_set() != NULL, "Sanity");
1879 return (address) heap->collection_set()->biased_map_address();
1880 }
1881
1882 address ShenandoahHeap::cancelled_gc_addr() {
1883 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
1884 }
1885
1886 address ShenandoahHeap::gc_state_addr() {
1887 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
1888 }
1889
1890 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
1891 return Atomic::load(&_bytes_allocated_since_gc_start);
1892 }
1893
1894 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
1895 Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0);
1896 }
1897
1898 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
1899 _degenerated_gc_in_progress.set_cond(in_progress);
1900 }
1901
1902 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
1903 _full_gc_in_progress.set_cond(in_progress);
1904 }
1905
1906 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
1907 assert (is_full_gc_in_progress(), "should be");
1908 _full_gc_move_in_progress.set_cond(in_progress);
1909 }
1910
1911 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
1912 set_gc_state_mask(UPDATEREFS, in_progress);
1913 }
1914
1915 void ShenandoahHeap::register_nmethod(nmethod* nm) {
1916 ShenandoahCodeRoots::register_nmethod(nm);
1917 }
1918
1919 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
1920 ShenandoahCodeRoots::unregister_nmethod(nm);
1921 }
1922
1923 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
1924 ShenandoahCodeRoots::flush_nmethod(nm);
1925 }
1926
1927 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
1928 heap_region_containing(o)->record_pin();
1929 return o;
1930 }
1931
1932 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
1933 ShenandoahHeapRegion* r = heap_region_containing(o);
1934 assert(r != NULL, "Sanity");
1935 assert(r->pin_count() > 0, "Region " SIZE_FORMAT " should have non-zero pins", r->index());
1936 r->record_unpin();
1937 }
1938
1939 void ShenandoahHeap::sync_pinned_region_status() {
1940 ShenandoahHeapLocker locker(lock());
1941
1942 for (size_t i = 0; i < num_regions(); i++) {
1943 ShenandoahHeapRegion *r = get_region(i);
1944 if (r->is_active()) {
1945 if (r->is_pinned()) {
1946 if (r->pin_count() == 0) {
1947 r->make_unpinned();
1948 }
1949 } else {
1950 if (r->pin_count() > 0) {
1951 r->make_pinned();
1952 }
1953 }
1954 }
1955 }
1956
1957 assert_pinned_region_status();
1958 }
1959
1960 #ifdef ASSERT
1961 void ShenandoahHeap::assert_pinned_region_status() {
1962 for (size_t i = 0; i < num_regions(); i++) {
1963 ShenandoahHeapRegion* r = get_region(i);
1964 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
1965 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
1966 }
1967 }
1968 #endif
1969
1970 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
1971 return _gc_timer;
1972 }
1973
1974 void ShenandoahHeap::prepare_concurrent_roots() {
1975 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1976 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1977 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
1978 set_concurrent_weak_root_in_progress(true);
1979 if (unload_classes()) {
1980 _unloader.prepare();
1981 }
1982 }
1983
1984 void ShenandoahHeap::finish_concurrent_roots() {
1985 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1986 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1987 if (unload_classes()) {
1988 _unloader.finish();
1989 }
1990 }
1991
1992 #ifdef ASSERT
1993 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
1994 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
1995
1996 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1997 if (UseDynamicNumberOfGCThreads) {
1998 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
1999 } else {
2000 // Use ParallelGCThreads inside safepoints
2001 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
2002 }
2003 } else {
2004 if (UseDynamicNumberOfGCThreads) {
2005 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2006 } else {
2007 // Use ConcGCThreads outside safepoints
2008 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2009 }
2010 }
2011 }
2012 #endif
2013
2014 ShenandoahVerifier* ShenandoahHeap::verifier() {
2015 guarantee(ShenandoahVerify, "Should be enabled");
2016 assert (_verifier != NULL, "sanity");
2017 return _verifier;
2018 }
2019
2020 template<bool CONCURRENT>
2021 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2022 private:
2023 ShenandoahHeap* _heap;
2024 ShenandoahRegionIterator* _regions;
2025 public:
2026 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
2027 AbstractGangTask("Shenandoah Update References"),
2028 _heap(ShenandoahHeap::heap()),
2029 _regions(regions) {
2030 }
2031
2032 void work(uint worker_id) {
2033 if (CONCURRENT) {
2034 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2035 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2036 do_work<ShenandoahConcUpdateRefsClosure>();
2037 } else {
2038 ShenandoahParallelWorkerSession worker_session(worker_id);
2039 do_work<ShenandoahSTWUpdateRefsClosure>();
2040 }
2041 }
2042
2043 private:
2044 template<class T>
2045 void do_work() {
2046 T cl;
2047 ShenandoahHeapRegion* r = _regions->next();
2048 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2049 while (r != NULL) {
2050 HeapWord* update_watermark = r->get_update_watermark();
2051 assert (update_watermark >= r->bottom(), "sanity");
2052 if (r->is_active() && !r->is_cset()) {
2053 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2054 }
2055 if (ShenandoahPacing) {
2056 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2057 }
2058 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2059 return;
2060 }
2061 r = _regions->next();
2062 }
2063 }
2064 };
2065
2066 void ShenandoahHeap::update_heap_references(bool concurrent) {
2067 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2068
2069 if (concurrent) {
2070 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator);
2071 workers()->run_task(&task);
2072 } else {
2073 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
2074 workers()->run_task(&task);
2075 }
2076 }
2077
2078
2079 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2080 private:
2081 ShenandoahHeapLock* const _lock;
2082
2083 public:
2084 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2085
2086 void heap_region_do(ShenandoahHeapRegion* r) {
2087 // Drop unnecessary "pinned" state from regions that does not have CP marks
2088 // anymore, as this would allow trashing them.
2089
2090 if (r->is_active()) {
2091 if (r->is_pinned()) {
2092 if (r->pin_count() == 0) {
2093 ShenandoahHeapLocker locker(_lock);
2094 r->make_unpinned();
2095 }
2096 } else {
2097 if (r->pin_count() > 0) {
2098 ShenandoahHeapLocker locker(_lock);
2099 r->make_pinned();
2100 }
2101 }
2102 }
2103 }
2104
2105 bool is_thread_safe() { return true; }
2106 };
2107
2108 void ShenandoahHeap::update_heap_region_states(bool concurrent) {
2109 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2110 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2111
2112 {
2113 ShenandoahGCPhase phase(concurrent ?
2114 ShenandoahPhaseTimings::final_update_refs_update_region_states :
2115 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states);
2116 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2117 parallel_heap_region_iterate(&cl);
2118
2119 assert_pinned_region_status();
2120 }
2121
2122 {
2123 ShenandoahGCPhase phase(concurrent ?
2124 ShenandoahPhaseTimings::final_update_refs_trash_cset :
2125 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset);
2126 trash_cset_regions();
2127 }
2128 }
2129
2130 void ShenandoahHeap::rebuild_free_set(bool concurrent) {
2131 {
2132 ShenandoahGCPhase phase(concurrent ?
2133 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
2134 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
2135 ShenandoahHeapLocker locker(lock());
2136 _free_set->rebuild();
2137 }
2138 }
2139
2140 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2141 print_on(st);
2142 print_heap_regions_on(st);
2143 }
2144
2145 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2146 size_t slice = r->index() / _bitmap_regions_per_slice;
2147
2148 size_t regions_from = _bitmap_regions_per_slice * slice;
2149 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2150 for (size_t g = regions_from; g < regions_to; g++) {
2151 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2152 if (skip_self && g == r->index()) continue;
2153 if (get_region(g)->is_committed()) {
2154 return true;
2155 }
2156 }
2157 return false;
2158 }
2159
2160 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2161 shenandoah_assert_heaplocked();
2162
2163 // Bitmaps in special regions do not need commits
2164 if (_bitmap_region_special) {
2165 return true;
2166 }
2167
2168 if (is_bitmap_slice_committed(r, true)) {
2169 // Some other region from the group is already committed, meaning the bitmap
2170 // slice is already committed, we exit right away.
2171 return true;
2172 }
2173
2174 // Commit the bitmap slice:
2175 size_t slice = r->index() / _bitmap_regions_per_slice;
2176 size_t off = _bitmap_bytes_per_slice * slice;
2177 size_t len = _bitmap_bytes_per_slice;
2178 char* start = (char*) _bitmap_region.start() + off;
2179
2180 if (!os::commit_memory(start, len, false)) {
2181 return false;
2182 }
2183
2184 if (AlwaysPreTouch) {
2185 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size);
2186 }
2187
2188 return true;
2189 }
2190
2191 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2192 shenandoah_assert_heaplocked();
2193
2194 // Bitmaps in special regions do not need uncommits
2195 if (_bitmap_region_special) {
2196 return true;
2197 }
2198
2199 if (is_bitmap_slice_committed(r, true)) {
2200 // Some other region from the group is still committed, meaning the bitmap
2201 // slice is should stay committed, exit right away.
2202 return true;
2203 }
2204
2205 // Uncommit the bitmap slice:
2206 size_t slice = r->index() / _bitmap_regions_per_slice;
2207 size_t off = _bitmap_bytes_per_slice * slice;
2208 size_t len = _bitmap_bytes_per_slice;
2209 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2210 return false;
2211 }
2212 return true;
2213 }
2214
2215 void ShenandoahHeap::safepoint_synchronize_begin() {
2216 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2217 SuspendibleThreadSet::synchronize();
2218 }
2219 }
2220
2221 void ShenandoahHeap::safepoint_synchronize_end() {
2222 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2223 SuspendibleThreadSet::desynchronize();
2224 }
2225 }
2226
2227 void ShenandoahHeap::entry_uncommit(double shrink_before, size_t shrink_until) {
2228 static const char *msg = "Concurrent uncommit";
2229 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
2230 EventMark em("%s", msg);
2231
2232 op_uncommit(shrink_before, shrink_until);
2233 }
2234
2235 void ShenandoahHeap::try_inject_alloc_failure() {
2236 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2237 _inject_alloc_failure.set();
2238 os::naked_short_sleep(1);
2239 if (cancelled_gc()) {
2240 log_info(gc)("Allocation failure was successfully injected");
2241 }
2242 }
2243 }
2244
2245 bool ShenandoahHeap::should_inject_alloc_failure() {
2246 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2247 }
2248
2249 void ShenandoahHeap::initialize_serviceability() {
2250 _memory_pool = new ShenandoahMemoryPool(this);
2251 _cycle_memory_manager.add_pool(_memory_pool);
2252 _stw_memory_manager.add_pool(_memory_pool);
2253 }
2254
2255 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2256 GrowableArray<GCMemoryManager*> memory_managers(2);
2257 memory_managers.append(&_cycle_memory_manager);
2258 memory_managers.append(&_stw_memory_manager);
2259 return memory_managers;
2260 }
2261
2262 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2263 GrowableArray<MemoryPool*> memory_pools(1);
2264 memory_pools.append(_memory_pool);
2265 return memory_pools;
2266 }
2267
2268 MemoryUsage ShenandoahHeap::memory_usage() {
2269 return _memory_pool->get_memory_usage();
2270 }
2271
2272 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2273 _heap(ShenandoahHeap::heap()),
2274 _index(0) {}
2275
2276 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2277 _heap(heap),
2278 _index(0) {}
2279
2280 void ShenandoahRegionIterator::reset() {
2281 _index = 0;
2282 }
2283
2284 bool ShenandoahRegionIterator::has_next() const {
2285 return _index < _heap->num_regions();
2286 }
2287
2288 char ShenandoahHeap::gc_state() const {
2289 return _gc_state.raw_value();
2290 }
2291
2292 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2293 #ifdef ASSERT
2294 assert(_liveness_cache != NULL, "sanity");
2295 assert(worker_id < _max_workers, "sanity");
2296 for (uint i = 0; i < num_regions(); i++) {
2297 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2298 }
2299 #endif
2300 return _liveness_cache[worker_id];
2301 }
2302
2303 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2304 assert(worker_id < _max_workers, "sanity");
2305 assert(_liveness_cache != NULL, "sanity");
2306 ShenandoahLiveData* ld = _liveness_cache[worker_id];
2307 for (uint i = 0; i < num_regions(); i++) {
2308 ShenandoahLiveData live = ld[i];
2309 if (live > 0) {
2310 ShenandoahHeapRegion* r = get_region(i);
2311 r->increase_live_data_gc_words(live);
2312 ld[i] = 0;
2313 }
2314 }
2315 }