1 /*
2 * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2013, 2022, Red Hat, Inc. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #include "precompiled.hpp"
27 #include "memory/allocation.hpp"
28 #include "memory/universe.hpp"
29
30 #include "gc/shared/gcArguments.hpp"
31 #include "gc/shared/gcTimer.hpp"
32 #include "gc/shared/gcTraceTime.inline.hpp"
33 #include "gc/shared/locationPrinter.inline.hpp"
34 #include "gc/shared/memAllocator.hpp"
35 #include "gc/shared/plab.hpp"
36 #include "gc/shared/tlab_globals.hpp"
37
38 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
39 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
40 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
41 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
42 #include "gc/shenandoah/shenandoahConcurrentMark.hpp"
43 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
44 #include "gc/shenandoah/shenandoahControlThread.hpp"
45 #include "gc/shenandoah/shenandoahFreeSet.hpp"
46 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
47 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
48 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
49 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
50 #include "gc/shenandoah/shenandoahInitLogger.hpp"
51 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
52 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
53 #include "gc/shenandoah/shenandoahMetrics.hpp"
54 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
55 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
56 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
57 #include "gc/shenandoah/shenandoahPadding.hpp"
58 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
59 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
60 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
61 #include "gc/shenandoah/shenandoahSTWMark.hpp"
62 #include "gc/shenandoah/shenandoahUtils.hpp"
63 #include "gc/shenandoah/shenandoahVerifier.hpp"
64 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
65 #include "gc/shenandoah/shenandoahVMOperations.hpp"
66 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
67 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
68 #include "gc/shenandoah/mode/shenandoahIUMode.hpp"
69 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
70 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
71 #if INCLUDE_JFR
72 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
73 #endif
74
75 #include "classfile/systemDictionary.hpp"
76 #include "code/codeCache.hpp"
77 #include "memory/classLoaderMetaspace.hpp"
78 #include "memory/metaspaceUtils.hpp"
79 #include "nmt/mallocTracker.hpp"
80 #include "nmt/memTracker.hpp"
81 #include "oops/compressedOops.inline.hpp"
82 #include "prims/jvmtiTagMap.hpp"
83 #include "runtime/atomic.hpp"
84 #include "runtime/globals.hpp"
85 #include "runtime/interfaceSupport.inline.hpp"
86 #include "runtime/java.hpp"
87 #include "runtime/orderAccess.hpp"
88 #include "runtime/safepointMechanism.hpp"
89 #include "runtime/vmThread.hpp"
90 #include "utilities/events.hpp"
91 #include "utilities/powerOfTwo.hpp"
92
93 class ShenandoahPretouchHeapTask : public WorkerTask {
94 private:
95 ShenandoahRegionIterator _regions;
96 const size_t _page_size;
97 public:
98 ShenandoahPretouchHeapTask(size_t page_size) :
99 WorkerTask("Shenandoah Pretouch Heap"),
100 _page_size(page_size) {}
101
102 virtual void work(uint worker_id) {
103 ShenandoahHeapRegion* r = _regions.next();
104 while (r != nullptr) {
105 if (r->is_committed()) {
106 os::pretouch_memory(r->bottom(), r->end(), _page_size);
107 }
108 r = _regions.next();
109 }
110 }
111 };
112
113 class ShenandoahPretouchBitmapTask : public WorkerTask {
114 private:
115 ShenandoahRegionIterator _regions;
116 char* _bitmap_base;
117 const size_t _bitmap_size;
118 const size_t _page_size;
119 public:
120 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
121 WorkerTask("Shenandoah Pretouch Bitmap"),
122 _bitmap_base(bitmap_base),
123 _bitmap_size(bitmap_size),
124 _page_size(page_size) {}
125
126 virtual void work(uint worker_id) {
127 ShenandoahHeapRegion* r = _regions.next();
128 while (r != nullptr) {
129 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
130 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
131 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
132
133 if (r->is_committed()) {
134 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
135 }
136
137 r = _regions.next();
138 }
139 }
140 };
141
142 jint ShenandoahHeap::initialize() {
143 //
144 // Figure out heap sizing
145 //
146
147 size_t init_byte_size = InitialHeapSize;
148 size_t min_byte_size = MinHeapSize;
149 size_t max_byte_size = MaxHeapSize;
150 size_t heap_alignment = HeapAlignment;
151
152 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
153
154 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
155 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
156
157 _num_regions = ShenandoahHeapRegion::region_count();
158 assert(_num_regions == (max_byte_size / reg_size_bytes),
159 "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT,
160 _num_regions, max_byte_size, reg_size_bytes);
161
162 // Now we know the number of regions, initialize the heuristics.
163 initialize_heuristics();
164
165 size_t num_committed_regions = init_byte_size / reg_size_bytes;
166 num_committed_regions = MIN2(num_committed_regions, _num_regions);
167 assert(num_committed_regions <= _num_regions, "sanity");
168 _initial_size = num_committed_regions * reg_size_bytes;
169
170 size_t num_min_regions = min_byte_size / reg_size_bytes;
171 num_min_regions = MIN2(num_min_regions, _num_regions);
172 assert(num_min_regions <= _num_regions, "sanity");
173 _minimum_size = num_min_regions * reg_size_bytes;
174
175 // Default to max heap size.
176 _soft_max_size = _num_regions * reg_size_bytes;
177
178 _committed = _initial_size;
179
180 size_t heap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
181 size_t bitmap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
182 size_t region_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
183
184 //
185 // Reserve and commit memory for heap
186 //
187
188 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
189 initialize_reserved_region(heap_rs);
190 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
191 _heap_region_special = heap_rs.special();
192
193 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
194 "Misaligned heap: " PTR_FORMAT, p2i(base()));
195 os::trace_page_sizes_for_requested_size("Heap",
196 max_byte_size, heap_alignment,
197 heap_rs.base(),
198 heap_rs.size(), heap_rs.page_size());
199
200 #if SHENANDOAH_OPTIMIZED_MARKTASK
201 // The optimized ShenandoahMarkTask takes some bits away from the full object bits.
202 // Fail if we ever attempt to address more than we can.
203 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) {
204 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
205 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
206 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
207 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable());
208 vm_exit_during_initialization("Fatal Error", buf);
209 }
210 #endif
211
212 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
213 if (!_heap_region_special) {
214 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
215 "Cannot commit heap memory");
216 }
217
218 //
219 // Reserve and commit memory for bitmap(s)
220 //
221
222 size_t bitmap_size_orig = ShenandoahMarkBitMap::compute_size(heap_rs.size());
223 _bitmap_size = align_up(bitmap_size_orig, bitmap_page_size);
224
225 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor();
226
227 guarantee(bitmap_bytes_per_region != 0,
228 "Bitmap bytes per region should not be zero");
229 guarantee(is_power_of_2(bitmap_bytes_per_region),
230 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
231
232 if (bitmap_page_size > bitmap_bytes_per_region) {
233 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
234 _bitmap_bytes_per_slice = bitmap_page_size;
235 } else {
236 _bitmap_regions_per_slice = 1;
237 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
238 }
239
240 guarantee(_bitmap_regions_per_slice >= 1,
241 "Should have at least one region per slice: " SIZE_FORMAT,
242 _bitmap_regions_per_slice);
243
244 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
245 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
246 _bitmap_bytes_per_slice, bitmap_page_size);
247
248 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
249 os::trace_page_sizes_for_requested_size("Mark Bitmap",
250 bitmap_size_orig, bitmap_page_size,
251 bitmap.base(),
252 bitmap.size(), bitmap.page_size());
253 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
254 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
255 _bitmap_region_special = bitmap.special();
256
257 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
258 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
259 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
260 if (!_bitmap_region_special) {
261 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
262 "Cannot commit bitmap memory");
263 }
264
265 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions, _max_workers);
266
267 if (ShenandoahVerify) {
268 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
269 os::trace_page_sizes_for_requested_size("Verify Bitmap",
270 bitmap_size_orig, bitmap_page_size,
271 verify_bitmap.base(),
272 verify_bitmap.size(), verify_bitmap.page_size());
273 if (!verify_bitmap.special()) {
274 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
275 "Cannot commit verification bitmap memory");
276 }
277 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
278 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
279 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
280 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
281 }
282
283 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
284 size_t aux_bitmap_page_size = bitmap_page_size;
285 #ifdef LINUX
286 // In THP "advise" mode, we refrain from advising the system to use large pages
287 // since we know these commits will be short lived, and there is no reason to trash
288 // the THP area with this bitmap.
289 if (UseTransparentHugePages) {
290 aux_bitmap_page_size = os::vm_page_size();
291 }
292 #endif
293 ReservedSpace aux_bitmap(_bitmap_size, aux_bitmap_page_size);
294 os::trace_page_sizes_for_requested_size("Aux Bitmap",
295 bitmap_size_orig, aux_bitmap_page_size,
296 aux_bitmap.base(),
297 aux_bitmap.size(), aux_bitmap.page_size());
298 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
299 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
300 _aux_bitmap_region_special = aux_bitmap.special();
301 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
302
303 //
304 // Create regions and region sets
305 //
306 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
307 size_t region_storage_size_orig = region_align * _num_regions;
308 size_t region_storage_size = align_up(region_storage_size_orig,
309 MAX2(region_page_size, os::vm_allocation_granularity()));
310
311 ReservedSpace region_storage(region_storage_size, region_page_size);
312 os::trace_page_sizes_for_requested_size("Region Storage",
313 region_storage_size_orig, region_page_size,
314 region_storage.base(),
315 region_storage.size(), region_storage.page_size());
316 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
317 if (!region_storage.special()) {
318 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
319 "Cannot commit region memory");
320 }
321
322 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks.
323 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there.
324 // If not successful, bite a bullet and allocate at whatever address.
325 {
326 const size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
327 const size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align);
328 const size_t cset_page_size = os::vm_page_size();
329
330 uintptr_t min = round_up_power_of_2(cset_align);
331 uintptr_t max = (1u << 30u);
332 ReservedSpace cset_rs;
333
334 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
335 char* req_addr = (char*)addr;
336 assert(is_aligned(req_addr, cset_align), "Should be aligned");
337 cset_rs = ReservedSpace(cset_size, cset_align, cset_page_size, req_addr);
338 if (cset_rs.is_reserved()) {
339 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr);
340 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
341 break;
342 }
343 }
344
345 if (_collection_set == nullptr) {
346 cset_rs = ReservedSpace(cset_size, cset_align, os::vm_page_size());
347 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
348 }
349 os::trace_page_sizes_for_requested_size("Collection Set",
350 cset_size, cset_page_size,
351 cset_rs.base(),
352 cset_rs.size(), cset_rs.page_size());
353 }
354
355 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
356 _free_set = new ShenandoahFreeSet(this, _num_regions);
357
358 {
359 ShenandoahHeapLocker locker(lock());
360
361 for (size_t i = 0; i < _num_regions; i++) {
362 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
363 bool is_committed = i < num_committed_regions;
364 void* loc = region_storage.base() + i * region_align;
365
366 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
367 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
368
369 _marking_context->initialize_top_at_mark_start(r);
370 _regions[i] = r;
371 assert(!collection_set()->is_in(i), "New region should not be in collection set");
372 }
373
374 // Initialize to complete
375 _marking_context->mark_complete();
376
377 _free_set->rebuild();
378 }
379
380 if (AlwaysPreTouch) {
381 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
382 // before initialize() below zeroes it with initializing thread. For any given region,
383 // we touch the region and the corresponding bitmaps from the same thread.
384 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
385
386 _pretouch_heap_page_size = heap_page_size;
387 _pretouch_bitmap_page_size = bitmap_page_size;
388
389 #ifdef LINUX
390 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
391 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
392 // them into huge one. Therefore, we need to pretouch with smaller pages.
393 if (UseTransparentHugePages) {
394 _pretouch_heap_page_size = (size_t)os::vm_page_size();
395 _pretouch_bitmap_page_size = (size_t)os::vm_page_size();
396 }
397 #endif
398
399 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
400 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
401
402 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size);
403 _workers->run_task(&bcl);
404
405 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size);
406 _workers->run_task(&hcl);
407 }
408
409 //
410 // Initialize the rest of GC subsystems
411 //
412
413 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
414 for (uint worker = 0; worker < _max_workers; worker++) {
415 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
416 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
417 }
418
419 // There should probably be Shenandoah-specific options for these,
420 // just as there are G1-specific options.
421 {
422 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
423 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
424 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
425 }
426
427 _monitoring_support = new ShenandoahMonitoringSupport(this);
428 _phase_timings = new ShenandoahPhaseTimings(max_workers());
429 ShenandoahCodeRoots::initialize();
430
431 if (ShenandoahPacing) {
432 _pacer = new ShenandoahPacer(this);
433 _pacer->setup_for_idle();
434 } else {
435 _pacer = nullptr;
436 }
437
438 _control_thread = new ShenandoahControlThread();
439
440 ShenandoahInitLogger::print();
441
442 return JNI_OK;
443 }
444
445 void ShenandoahHeap::initialize_mode() {
446 if (ShenandoahGCMode != nullptr) {
447 if (strcmp(ShenandoahGCMode, "satb") == 0) {
448 _gc_mode = new ShenandoahSATBMode();
449 } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
450 _gc_mode = new ShenandoahIUMode();
451 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
452 _gc_mode = new ShenandoahPassiveMode();
453 } else {
454 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
455 }
456 } else {
457 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)");
458 }
459 _gc_mode->initialize_flags();
460 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
461 vm_exit_during_initialization(
462 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
463 _gc_mode->name()));
464 }
465 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
466 vm_exit_during_initialization(
467 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
468 _gc_mode->name()));
469 }
470 }
471
472 void ShenandoahHeap::initialize_heuristics() {
473 assert(_gc_mode != nullptr, "Must be initialized");
474 _heuristics = _gc_mode->initialize_heuristics();
475
476 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
477 vm_exit_during_initialization(
478 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
479 _heuristics->name()));
480 }
481 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
482 vm_exit_during_initialization(
483 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
484 _heuristics->name()));
485 }
486 }
487
488 #ifdef _MSC_VER
489 #pragma warning( push )
490 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
491 #endif
492
493 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
494 CollectedHeap(),
495 _initial_size(0),
496 _used(0),
497 _committed(0),
498 _bytes_allocated_since_gc_start(0),
499 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
500 _workers(nullptr),
501 _safepoint_workers(nullptr),
502 _heap_region_special(false),
503 _num_regions(0),
504 _regions(nullptr),
505 _update_refs_iterator(this),
506 _gc_no_progress_count(0),
507 _control_thread(nullptr),
508 _shenandoah_policy(policy),
509 _gc_mode(nullptr),
510 _heuristics(nullptr),
511 _free_set(nullptr),
512 _pacer(nullptr),
513 _verifier(nullptr),
514 _phase_timings(nullptr),
515 _monitoring_support(nullptr),
516 _memory_pool(nullptr),
517 _stw_memory_manager("Shenandoah Pauses"),
518 _cycle_memory_manager("Shenandoah Cycles"),
519 _gc_timer(new ConcurrentGCTimer()),
520 _soft_ref_policy(),
521 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
522 _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))),
523 _marking_context(nullptr),
524 _bitmap_size(0),
525 _bitmap_regions_per_slice(0),
526 _bitmap_bytes_per_slice(0),
527 _bitmap_region_special(false),
528 _aux_bitmap_region_special(false),
529 _liveness_cache(nullptr),
530 _collection_set(nullptr)
531 {
532 // Initialize GC mode early, so we can adjust barrier support
533 initialize_mode();
534 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
535
536 _max_workers = MAX2(_max_workers, 1U);
537 _workers = new ShenandoahWorkerThreads("Shenandoah GC Threads", _max_workers);
538 if (_workers == nullptr) {
539 vm_exit_during_initialization("Failed necessary allocation.");
540 } else {
541 _workers->initialize_workers();
542 }
543
544 if (ParallelGCThreads > 1) {
545 _safepoint_workers = new ShenandoahWorkerThreads("Safepoint Cleanup Thread",
546 ParallelGCThreads);
547 _safepoint_workers->initialize_workers();
548 }
549 }
550
551 #ifdef _MSC_VER
552 #pragma warning( pop )
553 #endif
554
555 class ShenandoahResetBitmapTask : public WorkerTask {
556 private:
557 ShenandoahRegionIterator _regions;
558
559 public:
560 ShenandoahResetBitmapTask() :
561 WorkerTask("Shenandoah Reset Bitmap") {}
562
563 void work(uint worker_id) {
564 ShenandoahHeapRegion* region = _regions.next();
565 ShenandoahHeap* heap = ShenandoahHeap::heap();
566 ShenandoahMarkingContext* const ctx = heap->marking_context();
567 while (region != nullptr) {
568 if (heap->is_bitmap_slice_committed(region)) {
569 ctx->clear_bitmap(region);
570 }
571 region = _regions.next();
572 }
573 }
574 };
575
576 void ShenandoahHeap::reset_mark_bitmap() {
577 assert_gc_workers(_workers->active_workers());
578 mark_incomplete_marking_context();
579
580 ShenandoahResetBitmapTask task;
581 _workers->run_task(&task);
582 }
583
584 void ShenandoahHeap::print_on(outputStream* st) const {
585 st->print_cr("Shenandoah Heap");
586 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
587 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
588 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
589 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
590 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
591 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
592 num_regions(),
593 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
594 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
595
596 st->print("Status: ");
597 if (has_forwarded_objects()) st->print("has forwarded objects, ");
598 if (is_concurrent_mark_in_progress()) st->print("marking, ");
599 if (is_evacuation_in_progress()) st->print("evacuating, ");
600 if (is_update_refs_in_progress()) st->print("updating refs, ");
601 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
602 if (is_full_gc_in_progress()) st->print("full gc, ");
603 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
604 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
605 if (is_concurrent_strong_root_in_progress() &&
606 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
607
608 if (cancelled_gc()) {
609 st->print("cancelled");
610 } else {
611 st->print("not cancelled");
612 }
613 st->cr();
614
615 st->print_cr("Reserved region:");
616 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
617 p2i(reserved_region().start()),
618 p2i(reserved_region().end()));
619
620 ShenandoahCollectionSet* cset = collection_set();
621 st->print_cr("Collection set:");
622 if (cset != nullptr) {
623 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
624 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
625 } else {
626 st->print_cr(" (null)");
627 }
628
629 st->cr();
630 MetaspaceUtils::print_on(st);
631
632 if (Verbose) {
633 st->cr();
634 print_heap_regions_on(st);
635 }
636 }
637
638 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
639 public:
640 void do_thread(Thread* thread) {
641 assert(thread != nullptr, "Sanity");
642 assert(thread->is_Worker_thread(), "Only worker thread expected");
643 ShenandoahThreadLocalData::initialize_gclab(thread);
644 }
645 };
646
647 void ShenandoahHeap::post_initialize() {
648 CollectedHeap::post_initialize();
649 MutexLocker ml(Threads_lock);
650
651 ShenandoahInitWorkerGCLABClosure init_gclabs;
652 _workers->threads_do(&init_gclabs);
653
654 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
655 // Now, we will let WorkerThreads to initialize gclab when new worker is created.
656 _workers->set_initialize_gclab();
657 if (_safepoint_workers != nullptr) {
658 _safepoint_workers->threads_do(&init_gclabs);
659 _safepoint_workers->set_initialize_gclab();
660 }
661
662 _heuristics->initialize();
663
664 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
665 }
666
667 size_t ShenandoahHeap::used() const {
668 return Atomic::load(&_used);
669 }
670
671 size_t ShenandoahHeap::committed() const {
672 return Atomic::load(&_committed);
673 }
674
675 size_t ShenandoahHeap::available() const {
676 return free_set()->available();
677 }
678
679 void ShenandoahHeap::increase_committed(size_t bytes) {
680 shenandoah_assert_heaplocked_or_safepoint();
681 _committed += bytes;
682 }
683
684 void ShenandoahHeap::decrease_committed(size_t bytes) {
685 shenandoah_assert_heaplocked_or_safepoint();
686 _committed -= bytes;
687 }
688
689 void ShenandoahHeap::increase_used(size_t bytes) {
690 Atomic::add(&_used, bytes, memory_order_relaxed);
691 }
692
693 void ShenandoahHeap::set_used(size_t bytes) {
694 Atomic::store(&_used, bytes);
695 }
696
697 void ShenandoahHeap::decrease_used(size_t bytes) {
698 assert(used() >= bytes, "never decrease heap size by more than we've left");
699 Atomic::sub(&_used, bytes, memory_order_relaxed);
700 }
701
702 void ShenandoahHeap::increase_allocated(size_t bytes) {
703 Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed);
704 }
705
706 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
707 size_t bytes = words * HeapWordSize;
708 if (!waste) {
709 increase_used(bytes);
710 }
711 increase_allocated(bytes);
712 if (ShenandoahPacing) {
713 control_thread()->pacing_notify_alloc(words);
714 if (waste) {
715 pacer()->claim_for_alloc(words, true);
716 }
717 }
718 }
719
720 size_t ShenandoahHeap::capacity() const {
721 return committed();
722 }
723
724 size_t ShenandoahHeap::max_capacity() const {
725 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
726 }
727
728 size_t ShenandoahHeap::soft_max_capacity() const {
729 size_t v = Atomic::load(&_soft_max_size);
730 assert(min_capacity() <= v && v <= max_capacity(),
731 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
732 min_capacity(), v, max_capacity());
733 return v;
734 }
735
736 void ShenandoahHeap::set_soft_max_capacity(size_t v) {
737 assert(min_capacity() <= v && v <= max_capacity(),
738 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
739 min_capacity(), v, max_capacity());
740 Atomic::store(&_soft_max_size, v);
741 }
742
743 size_t ShenandoahHeap::min_capacity() const {
744 return _minimum_size;
745 }
746
747 size_t ShenandoahHeap::initial_capacity() const {
748 return _initial_size;
749 }
750
751 bool ShenandoahHeap::is_in(const void* p) const {
752 HeapWord* heap_base = (HeapWord*) base();
753 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
754 return p >= heap_base && p < last_region_end;
755 }
756
757 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
758 assert (ShenandoahUncommit, "should be enabled");
759
760 // Application allocates from the beginning of the heap, and GC allocates at
761 // the end of it. It is more efficient to uncommit from the end, so that applications
762 // could enjoy the near committed regions. GC allocations are much less frequent,
763 // and therefore can accept the committing costs.
764
765 size_t count = 0;
766 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
767 ShenandoahHeapRegion* r = get_region(i - 1);
768 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
769 ShenandoahHeapLocker locker(lock());
770 if (r->is_empty_committed()) {
771 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
772 break;
773 }
774
775 r->make_uncommitted();
776 count++;
777 }
778 }
779 SpinPause(); // allow allocators to take the lock
780 }
781
782 if (count > 0) {
783 control_thread()->notify_heap_changed();
784 }
785 }
786
787 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
788 // New object should fit the GCLAB size
789 size_t min_size = MAX2(size, PLAB::min_size());
790
791 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
792 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
793 new_size = MIN2(new_size, PLAB::max_size());
794 new_size = MAX2(new_size, PLAB::min_size());
795
796 // Record new heuristic value even if we take any shortcut. This captures
797 // the case when moderately-sized objects always take a shortcut. At some point,
798 // heuristics should catch up with them.
799 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
800
801 if (new_size < size) {
802 // New size still does not fit the object. Fall back to shared allocation.
803 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
804 return nullptr;
805 }
806
807 // Retire current GCLAB, and allocate a new one.
808 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
809 gclab->retire();
810
811 size_t actual_size = 0;
812 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
813 if (gclab_buf == nullptr) {
814 return nullptr;
815 }
816
817 assert (size <= actual_size, "allocation should fit");
818
819 if (ZeroTLAB) {
820 // ..and clear it.
821 Copy::zero_to_words(gclab_buf, actual_size);
822 } else {
823 // ...and zap just allocated object.
824 #ifdef ASSERT
825 // Skip mangling the space corresponding to the object header to
826 // ensure that the returned space is not considered parsable by
827 // any concurrent GC thread.
828 size_t hdr_size = oopDesc::header_size();
829 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
830 #endif // ASSERT
831 }
832 gclab->set_buf(gclab_buf, actual_size);
833 return gclab->allocate(size);
834 }
835
836 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
837 size_t requested_size,
838 size_t* actual_size) {
839 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
840 HeapWord* res = allocate_memory(req);
841 if (res != nullptr) {
842 *actual_size = req.actual_size();
843 } else {
844 *actual_size = 0;
845 }
846 return res;
847 }
848
849 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
850 size_t word_size,
851 size_t* actual_size) {
852 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
853 HeapWord* res = allocate_memory(req);
854 if (res != nullptr) {
855 *actual_size = req.actual_size();
856 } else {
857 *actual_size = 0;
858 }
859 return res;
860 }
861
862 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
863 intptr_t pacer_epoch = 0;
864 bool in_new_region = false;
865 HeapWord* result = nullptr;
866
867 if (req.is_mutator_alloc()) {
868 if (ShenandoahPacing) {
869 pacer()->pace_for_alloc(req.size());
870 pacer_epoch = pacer()->epoch();
871 }
872
873 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
874 result = allocate_memory_under_lock(req, in_new_region);
875 }
876
877 // Check that gc overhead is not exceeded.
878 //
879 // Shenandoah will grind along for quite a while allocating one
880 // object at a time using shared (non-tlab) allocations. This check
881 // is testing that the GC overhead limit has not been exceeded.
882 // This will notify the collector to start a cycle, but will raise
883 // an OOME to the mutator if the last Full GCs have not made progress.
884 if (result == nullptr && !req.is_lab_alloc() && get_gc_no_progress_count() > ShenandoahNoProgressThreshold) {
885 control_thread()->handle_alloc_failure(req, false);
886 return nullptr;
887 }
888
889 // Block until control thread reacted, then retry allocation.
890 //
891 // It might happen that one of the threads requesting allocation would unblock
892 // way later after GC happened, only to fail the second allocation, because
893 // other threads have already depleted the free storage. In this case, a better
894 // strategy is to try again, as long as GC makes progress (or until at least
895 // one full GC has completed).
896 size_t original_count = shenandoah_policy()->full_gc_count();
897 while (result == nullptr
898 && (get_gc_no_progress_count() == 0 || original_count == shenandoah_policy()->full_gc_count())) {
899 control_thread()->handle_alloc_failure(req);
900 result = allocate_memory_under_lock(req, in_new_region);
901 }
902
903 if (log_is_enabled(Debug, gc, alloc)) {
904 ResourceMark rm;
905 log_debug(gc, alloc)("Thread: %s, Result: " PTR_FORMAT ", Request: %s, Size: " SIZE_FORMAT ", Original: " SIZE_FORMAT ", Latest: " SIZE_FORMAT,
906 Thread::current()->name(), p2i(result), req.type_string(), req.size(), original_count, get_gc_no_progress_count());
907 }
908 } else {
909 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
910 result = allocate_memory_under_lock(req, in_new_region);
911 // Do not call handle_alloc_failure() here, because we cannot block.
912 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
913 }
914
915 if (in_new_region) {
916 control_thread()->notify_heap_changed();
917 }
918
919 if (result != nullptr) {
920 size_t requested = req.size();
921 size_t actual = req.actual_size();
922
923 assert (req.is_lab_alloc() || (requested == actual),
924 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
925 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
926
927 if (req.is_mutator_alloc()) {
928 notify_mutator_alloc_words(actual, false);
929
930 // If we requested more than we were granted, give the rest back to pacer.
931 // This only matters if we are in the same pacing epoch: do not try to unpace
932 // over the budget for the other phase.
933 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
934 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
935 }
936 } else {
937 increase_used(actual*HeapWordSize);
938 }
939 }
940
941 return result;
942 }
943
944 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
945 ShenandoahHeapLocker locker(lock());
946 return _free_set->allocate(req, in_new_region);
947 }
948
949 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
950 bool* gc_overhead_limit_was_exceeded) {
951 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
952 return allocate_memory(req);
953 }
954
955 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
956 size_t size,
957 Metaspace::MetadataType mdtype) {
958 MetaWord* result;
959
960 // Inform metaspace OOM to GC heuristics if class unloading is possible.
961 if (heuristics()->can_unload_classes()) {
962 ShenandoahHeuristics* h = heuristics();
963 h->record_metaspace_oom();
964 }
965
966 // Expand and retry allocation
967 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
968 if (result != nullptr) {
969 return result;
970 }
971
972 // Start full GC
973 collect(GCCause::_metadata_GC_clear_soft_refs);
974
975 // Retry allocation
976 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
977 if (result != nullptr) {
978 return result;
979 }
980
981 // Expand and retry allocation
982 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
983 if (result != nullptr) {
984 return result;
985 }
986
987 // Out of memory
988 return nullptr;
989 }
990
991 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
992 private:
993 ShenandoahHeap* const _heap;
994 Thread* const _thread;
995 public:
996 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
997 _heap(heap), _thread(Thread::current()) {}
998
999 void do_object(oop p) {
1000 shenandoah_assert_marked(nullptr, p);
1001 if (!p->is_forwarded()) {
1002 _heap->evacuate_object(p, _thread);
1003 }
1004 }
1005 };
1006
1007 class ShenandoahEvacuationTask : public WorkerTask {
1008 private:
1009 ShenandoahHeap* const _sh;
1010 ShenandoahCollectionSet* const _cs;
1011 bool _concurrent;
1012 public:
1013 ShenandoahEvacuationTask(ShenandoahHeap* sh,
1014 ShenandoahCollectionSet* cs,
1015 bool concurrent) :
1016 WorkerTask("Shenandoah Evacuation"),
1017 _sh(sh),
1018 _cs(cs),
1019 _concurrent(concurrent)
1020 {}
1021
1022 void work(uint worker_id) {
1023 if (_concurrent) {
1024 ShenandoahConcurrentWorkerSession worker_session(worker_id);
1025 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
1026 ShenandoahEvacOOMScope oom_evac_scope;
1027 do_work();
1028 } else {
1029 ShenandoahParallelWorkerSession worker_session(worker_id);
1030 ShenandoahEvacOOMScope oom_evac_scope;
1031 do_work();
1032 }
1033 }
1034
1035 private:
1036 void do_work() {
1037 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
1038 ShenandoahHeapRegion* r;
1039 while ((r =_cs->claim_next()) != nullptr) {
1040 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
1041 _sh->marked_object_iterate(r, &cl);
1042
1043 if (ShenandoahPacing) {
1044 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
1045 }
1046
1047 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1048 break;
1049 }
1050 }
1051 }
1052 };
1053
1054 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
1055 ShenandoahEvacuationTask task(this, _collection_set, concurrent);
1056 workers()->run_task(&task);
1057 }
1058
1059 void ShenandoahHeap::trash_cset_regions() {
1060 ShenandoahHeapLocker locker(lock());
1061
1062 ShenandoahCollectionSet* set = collection_set();
1063 ShenandoahHeapRegion* r;
1064 set->clear_current_index();
1065 while ((r = set->next()) != nullptr) {
1066 r->make_trash();
1067 }
1068 collection_set()->clear();
1069 }
1070
1071 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1072 st->print_cr("Heap Regions:");
1073 st->print_cr("Region state: EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HP=pinned humongous start");
1074 st->print_cr(" HC=humongous continuation, CS=collection set, TR=trash, P=pinned, CSP=pinned collection set");
1075 st->print_cr("BTE=bottom/top/end, TAMS=top-at-mark-start");
1076 st->print_cr("UWM=update watermark, U=used");
1077 st->print_cr("T=TLAB allocs, G=GCLAB allocs");
1078 st->print_cr("S=shared allocs, L=live data");
1079 st->print_cr("CP=critical pins");
1080
1081 for (size_t i = 0; i < num_regions(); i++) {
1082 get_region(i)->print_on(st);
1083 }
1084 }
1085
1086 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1087 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1088
1089 oop humongous_obj = cast_to_oop(start->bottom());
1090 size_t size = humongous_obj->size();
1091 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1092 size_t index = start->index() + required_regions - 1;
1093
1094 assert(!start->has_live(), "liveness must be zero");
1095
1096 for(size_t i = 0; i < required_regions; i++) {
1097 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1098 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1099 ShenandoahHeapRegion* region = get_region(index --);
1100
1101 assert(region->is_humongous(), "expect correct humongous start or continuation");
1102 assert(!region->is_cset(), "Humongous region should not be in collection set");
1103
1104 region->make_trash_immediate();
1105 }
1106 }
1107
1108 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1109 public:
1110 ShenandoahCheckCleanGCLABClosure() {}
1111 void do_thread(Thread* thread) {
1112 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1113 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1114 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1115 }
1116 };
1117
1118 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1119 private:
1120 bool const _resize;
1121 public:
1122 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1123 void do_thread(Thread* thread) {
1124 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1125 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1126 gclab->retire();
1127 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1128 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1129 }
1130 }
1131 };
1132
1133 void ShenandoahHeap::labs_make_parsable() {
1134 assert(UseTLAB, "Only call with UseTLAB");
1135
1136 ShenandoahRetireGCLABClosure cl(false);
1137
1138 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1139 ThreadLocalAllocBuffer& tlab = t->tlab();
1140 tlab.make_parsable();
1141 cl.do_thread(t);
1142 }
1143
1144 workers()->threads_do(&cl);
1145 }
1146
1147 void ShenandoahHeap::tlabs_retire(bool resize) {
1148 assert(UseTLAB, "Only call with UseTLAB");
1149 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1150
1151 ThreadLocalAllocStats stats;
1152
1153 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1154 ThreadLocalAllocBuffer& tlab = t->tlab();
1155 tlab.retire(&stats);
1156 if (resize) {
1157 tlab.resize();
1158 }
1159 }
1160
1161 stats.publish();
1162
1163 #ifdef ASSERT
1164 ShenandoahCheckCleanGCLABClosure cl;
1165 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1166 cl.do_thread(t);
1167 }
1168 workers()->threads_do(&cl);
1169 #endif
1170 }
1171
1172 void ShenandoahHeap::gclabs_retire(bool resize) {
1173 assert(UseTLAB, "Only call with UseTLAB");
1174 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1175
1176 ShenandoahRetireGCLABClosure cl(resize);
1177 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1178 cl.do_thread(t);
1179 }
1180 workers()->threads_do(&cl);
1181
1182 if (safepoint_workers() != nullptr) {
1183 safepoint_workers()->threads_do(&cl);
1184 }
1185 }
1186
1187 // Returns size in bytes
1188 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1189 if (ShenandoahElasticTLAB) {
1190 // With Elastic TLABs, return the max allowed size, and let the allocation path
1191 // figure out the safe size for current allocation.
1192 return ShenandoahHeapRegion::max_tlab_size_bytes();
1193 } else {
1194 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1195 }
1196 }
1197
1198 size_t ShenandoahHeap::max_tlab_size() const {
1199 // Returns size in words
1200 return ShenandoahHeapRegion::max_tlab_size_words();
1201 }
1202
1203 void ShenandoahHeap::collect(GCCause::Cause cause) {
1204 control_thread()->request_gc(cause);
1205 }
1206
1207 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1208 //assert(false, "Shouldn't need to do full collections");
1209 }
1210
1211 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1212 ShenandoahHeapRegion* r = heap_region_containing(addr);
1213 if (r != nullptr) {
1214 return r->block_start(addr);
1215 }
1216 return nullptr;
1217 }
1218
1219 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1220 ShenandoahHeapRegion* r = heap_region_containing(addr);
1221 return r->block_is_obj(addr);
1222 }
1223
1224 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1225 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1226 }
1227
1228 void ShenandoahHeap::prepare_for_verify() {
1229 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1230 labs_make_parsable();
1231 }
1232 }
1233
1234 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1235 tcl->do_thread(_control_thread);
1236 workers()->threads_do(tcl);
1237 if (_safepoint_workers != nullptr) {
1238 _safepoint_workers->threads_do(tcl);
1239 }
1240 }
1241
1242 void ShenandoahHeap::print_tracing_info() const {
1243 LogTarget(Info, gc, stats) lt;
1244 if (lt.is_enabled()) {
1245 ResourceMark rm;
1246 LogStream ls(lt);
1247
1248 phase_timings()->print_global_on(&ls);
1249
1250 ls.cr();
1251 ls.cr();
1252
1253 shenandoah_policy()->print_gc_stats(&ls);
1254
1255 ls.cr();
1256 ls.cr();
1257 }
1258 }
1259
1260 void ShenandoahHeap::verify(VerifyOption vo) {
1261 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1262 if (ShenandoahVerify) {
1263 verifier()->verify_generic(vo);
1264 } else {
1265 // TODO: Consider allocating verification bitmaps on demand,
1266 // and turn this on unconditionally.
1267 }
1268 }
1269 }
1270 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1271 return _free_set->capacity();
1272 }
1273
1274 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1275 private:
1276 MarkBitMap* _bitmap;
1277 ShenandoahScanObjectStack* _oop_stack;
1278 ShenandoahHeap* const _heap;
1279 ShenandoahMarkingContext* const _marking_context;
1280
1281 template <class T>
1282 void do_oop_work(T* p) {
1283 T o = RawAccess<>::oop_load(p);
1284 if (!CompressedOops::is_null(o)) {
1285 oop obj = CompressedOops::decode_not_null(o);
1286 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1287 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1288 return;
1289 }
1290 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1291
1292 assert(oopDesc::is_oop(obj), "must be a valid oop");
1293 if (!_bitmap->is_marked(obj)) {
1294 _bitmap->mark(obj);
1295 _oop_stack->push(obj);
1296 }
1297 }
1298 }
1299 public:
1300 ObjectIterateScanRootClosure(MarkBitMap* bitmap, ShenandoahScanObjectStack* oop_stack) :
1301 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1302 _marking_context(_heap->marking_context()) {}
1303 void do_oop(oop* p) { do_oop_work(p); }
1304 void do_oop(narrowOop* p) { do_oop_work(p); }
1305 };
1306
1307 /*
1308 * This is public API, used in preparation of object_iterate().
1309 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1310 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1311 * control, we call SH::tlabs_retire, SH::gclabs_retire.
1312 */
1313 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1314 // No-op.
1315 }
1316
1317 /*
1318 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1319 *
1320 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1321 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1322 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1323 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1324 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1325 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1326 * wiped the bitmap in preparation for next marking).
1327 *
1328 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1329 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1330 * is allowed to report dead objects, but is not required to do so.
1331 */
1332 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1333 // Reset bitmap
1334 if (!prepare_aux_bitmap_for_iteration())
1335 return;
1336
1337 ShenandoahScanObjectStack oop_stack;
1338 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1339 // Seed the stack with root scan
1340 scan_roots_for_iteration(&oop_stack, &oops);
1341
1342 // Work through the oop stack to traverse heap
1343 while (! oop_stack.is_empty()) {
1344 oop obj = oop_stack.pop();
1345 assert(oopDesc::is_oop(obj), "must be a valid oop");
1346 cl->do_object(obj);
1347 obj->oop_iterate(&oops);
1348 }
1349
1350 assert(oop_stack.is_empty(), "should be empty");
1351 // Reclaim bitmap
1352 reclaim_aux_bitmap_for_iteration();
1353 }
1354
1355 bool ShenandoahHeap::prepare_aux_bitmap_for_iteration() {
1356 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1357
1358 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1359 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1360 return false;
1361 }
1362 // Reset bitmap
1363 _aux_bit_map.clear();
1364 return true;
1365 }
1366
1367 void ShenandoahHeap::scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops) {
1368 // Process GC roots according to current GC cycle
1369 // This populates the work stack with initial objects
1370 // It is important to relinquish the associated locks before diving
1371 // into heap dumper
1372 uint n_workers = safepoint_workers() != nullptr ? safepoint_workers()->active_workers() : 1;
1373 ShenandoahHeapIterationRootScanner rp(n_workers);
1374 rp.roots_do(oops);
1375 }
1376
1377 void ShenandoahHeap::reclaim_aux_bitmap_for_iteration() {
1378 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1379 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1380 }
1381 }
1382
1383 // Closure for parallelly iterate objects
1384 class ShenandoahObjectIterateParScanClosure : public BasicOopIterateClosure {
1385 private:
1386 MarkBitMap* _bitmap;
1387 ShenandoahObjToScanQueue* _queue;
1388 ShenandoahHeap* const _heap;
1389 ShenandoahMarkingContext* const _marking_context;
1390
1391 template <class T>
1392 void do_oop_work(T* p) {
1393 T o = RawAccess<>::oop_load(p);
1394 if (!CompressedOops::is_null(o)) {
1395 oop obj = CompressedOops::decode_not_null(o);
1396 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1397 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1398 return;
1399 }
1400 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1401
1402 assert(oopDesc::is_oop(obj), "Must be a valid oop");
1403 if (_bitmap->par_mark(obj)) {
1404 _queue->push(ShenandoahMarkTask(obj));
1405 }
1406 }
1407 }
1408 public:
1409 ShenandoahObjectIterateParScanClosure(MarkBitMap* bitmap, ShenandoahObjToScanQueue* q) :
1410 _bitmap(bitmap), _queue(q), _heap(ShenandoahHeap::heap()),
1411 _marking_context(_heap->marking_context()) {}
1412 void do_oop(oop* p) { do_oop_work(p); }
1413 void do_oop(narrowOop* p) { do_oop_work(p); }
1414 };
1415
1416 // Object iterator for parallel heap iteraion.
1417 // The root scanning phase happenes in construction as a preparation of
1418 // parallel marking queues.
1419 // Every worker processes it's own marking queue. work-stealing is used
1420 // to balance workload.
1421 class ShenandoahParallelObjectIterator : public ParallelObjectIteratorImpl {
1422 private:
1423 uint _num_workers;
1424 bool _init_ready;
1425 MarkBitMap* _aux_bit_map;
1426 ShenandoahHeap* _heap;
1427 ShenandoahScanObjectStack _roots_stack; // global roots stack
1428 ShenandoahObjToScanQueueSet* _task_queues;
1429 public:
1430 ShenandoahParallelObjectIterator(uint num_workers, MarkBitMap* bitmap) :
1431 _num_workers(num_workers),
1432 _init_ready(false),
1433 _aux_bit_map(bitmap),
1434 _heap(ShenandoahHeap::heap()) {
1435 // Initialize bitmap
1436 _init_ready = _heap->prepare_aux_bitmap_for_iteration();
1437 if (!_init_ready) {
1438 return;
1439 }
1440
1441 ObjectIterateScanRootClosure oops(_aux_bit_map, &_roots_stack);
1442 _heap->scan_roots_for_iteration(&_roots_stack, &oops);
1443
1444 _init_ready = prepare_worker_queues();
1445 }
1446
1447 ~ShenandoahParallelObjectIterator() {
1448 // Reclaim bitmap
1449 _heap->reclaim_aux_bitmap_for_iteration();
1450 // Reclaim queue for workers
1451 if (_task_queues!= nullptr) {
1452 for (uint i = 0; i < _num_workers; ++i) {
1453 ShenandoahObjToScanQueue* q = _task_queues->queue(i);
1454 if (q != nullptr) {
1455 delete q;
1456 _task_queues->register_queue(i, nullptr);
1457 }
1458 }
1459 delete _task_queues;
1460 _task_queues = nullptr;
1461 }
1462 }
1463
1464 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
1465 if (_init_ready) {
1466 object_iterate_parallel(cl, worker_id, _task_queues);
1467 }
1468 }
1469
1470 private:
1471 // Divide global root_stack into worker queues
1472 bool prepare_worker_queues() {
1473 _task_queues = new ShenandoahObjToScanQueueSet((int) _num_workers);
1474 // Initialize queues for every workers
1475 for (uint i = 0; i < _num_workers; ++i) {
1476 ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue();
1477 _task_queues->register_queue(i, task_queue);
1478 }
1479 // Divide roots among the workers. Assume that object referencing distribution
1480 // is related with root kind, use round-robin to make every worker have same chance
1481 // to process every kind of roots
1482 size_t roots_num = _roots_stack.size();
1483 if (roots_num == 0) {
1484 // No work to do
1485 return false;
1486 }
1487
1488 for (uint j = 0; j < roots_num; j++) {
1489 uint stack_id = j % _num_workers;
1490 oop obj = _roots_stack.pop();
1491 _task_queues->queue(stack_id)->push(ShenandoahMarkTask(obj));
1492 }
1493 return true;
1494 }
1495
1496 void object_iterate_parallel(ObjectClosure* cl,
1497 uint worker_id,
1498 ShenandoahObjToScanQueueSet* queue_set) {
1499 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1500 assert(queue_set != nullptr, "task queue must not be null");
1501
1502 ShenandoahObjToScanQueue* q = queue_set->queue(worker_id);
1503 assert(q != nullptr, "object iterate queue must not be null");
1504
1505 ShenandoahMarkTask t;
1506 ShenandoahObjectIterateParScanClosure oops(_aux_bit_map, q);
1507
1508 // Work through the queue to traverse heap.
1509 // Steal when there is no task in queue.
1510 while (q->pop(t) || queue_set->steal(worker_id, t)) {
1511 oop obj = t.obj();
1512 assert(oopDesc::is_oop(obj), "must be a valid oop");
1513 cl->do_object(obj);
1514 obj->oop_iterate(&oops);
1515 }
1516 assert(q->is_empty(), "should be empty");
1517 }
1518 };
1519
1520 ParallelObjectIteratorImpl* ShenandoahHeap::parallel_object_iterator(uint workers) {
1521 return new ShenandoahParallelObjectIterator(workers, &_aux_bit_map);
1522 }
1523
1524 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1525 void ShenandoahHeap::keep_alive(oop obj) {
1526 if (is_concurrent_mark_in_progress() && (obj != nullptr)) {
1527 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1528 }
1529 }
1530
1531 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1532 for (size_t i = 0; i < num_regions(); i++) {
1533 ShenandoahHeapRegion* current = get_region(i);
1534 blk->heap_region_do(current);
1535 }
1536 }
1537
1538 class ShenandoahParallelHeapRegionTask : public WorkerTask {
1539 private:
1540 ShenandoahHeap* const _heap;
1541 ShenandoahHeapRegionClosure* const _blk;
1542
1543 shenandoah_padding(0);
1544 volatile size_t _index;
1545 shenandoah_padding(1);
1546
1547 public:
1548 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1549 WorkerTask("Shenandoah Parallel Region Operation"),
1550 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1551
1552 void work(uint worker_id) {
1553 ShenandoahParallelWorkerSession worker_session(worker_id);
1554 size_t stride = ShenandoahParallelRegionStride;
1555
1556 size_t max = _heap->num_regions();
1557 while (Atomic::load(&_index) < max) {
1558 size_t cur = Atomic::fetch_then_add(&_index, stride, memory_order_relaxed);
1559 size_t start = cur;
1560 size_t end = MIN2(cur + stride, max);
1561 if (start >= max) break;
1562
1563 for (size_t i = cur; i < end; i++) {
1564 ShenandoahHeapRegion* current = _heap->get_region(i);
1565 _blk->heap_region_do(current);
1566 }
1567 }
1568 }
1569 };
1570
1571 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1572 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1573 if (num_regions() > ShenandoahParallelRegionStride) {
1574 ShenandoahParallelHeapRegionTask task(blk);
1575 workers()->run_task(&task);
1576 } else {
1577 heap_region_iterate(blk);
1578 }
1579 }
1580
1581 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1582 private:
1583 ShenandoahMarkingContext* const _ctx;
1584 public:
1585 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1586
1587 void heap_region_do(ShenandoahHeapRegion* r) {
1588 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1589 if (r->is_active()) {
1590 // Check if region needs updating its TAMS. We have updated it already during concurrent
1591 // reset, so it is very likely we don't need to do another write here.
1592 if (_ctx->top_at_mark_start(r) != r->top()) {
1593 _ctx->capture_top_at_mark_start(r);
1594 }
1595 } else {
1596 assert(_ctx->top_at_mark_start(r) == r->top(),
1597 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1598 }
1599 }
1600
1601 bool is_thread_safe() { return true; }
1602 };
1603
1604 class ShenandoahRendezvousClosure : public HandshakeClosure {
1605 public:
1606 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
1607 inline void do_thread(Thread* thread) {}
1608 };
1609
1610 void ShenandoahHeap::rendezvous_threads() {
1611 ShenandoahRendezvousClosure cl;
1612 Handshake::execute(&cl);
1613 }
1614
1615 void ShenandoahHeap::recycle_trash() {
1616 free_set()->recycle_trash();
1617 }
1618
1619 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1620 private:
1621 ShenandoahMarkingContext* const _ctx;
1622 public:
1623 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1624
1625 void heap_region_do(ShenandoahHeapRegion* r) {
1626 if (r->is_active()) {
1627 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1628 // anyway to capture any updates that happened since now.
1629 r->clear_live_data();
1630 _ctx->capture_top_at_mark_start(r);
1631 }
1632 }
1633
1634 bool is_thread_safe() { return true; }
1635 };
1636
1637 void ShenandoahHeap::prepare_gc() {
1638 reset_mark_bitmap();
1639
1640 ShenandoahResetUpdateRegionStateClosure cl;
1641 parallel_heap_region_iterate(&cl);
1642 }
1643
1644 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1645 private:
1646 ShenandoahMarkingContext* const _ctx;
1647 ShenandoahHeapLock* const _lock;
1648
1649 public:
1650 ShenandoahFinalMarkUpdateRegionStateClosure() :
1651 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1652
1653 void heap_region_do(ShenandoahHeapRegion* r) {
1654 if (r->is_active()) {
1655 // All allocations past TAMS are implicitly live, adjust the region data.
1656 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1657 HeapWord *tams = _ctx->top_at_mark_start(r);
1658 HeapWord *top = r->top();
1659 if (top > tams) {
1660 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1661 }
1662
1663 // We are about to select the collection set, make sure it knows about
1664 // current pinning status. Also, this allows trashing more regions that
1665 // now have their pinning status dropped.
1666 if (r->is_pinned()) {
1667 if (r->pin_count() == 0) {
1668 ShenandoahHeapLocker locker(_lock);
1669 r->make_unpinned();
1670 }
1671 } else {
1672 if (r->pin_count() > 0) {
1673 ShenandoahHeapLocker locker(_lock);
1674 r->make_pinned();
1675 }
1676 }
1677
1678 // Remember limit for updating refs. It's guaranteed that we get no
1679 // from-space-refs written from here on.
1680 r->set_update_watermark_at_safepoint(r->top());
1681 } else {
1682 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1683 assert(_ctx->top_at_mark_start(r) == r->top(),
1684 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1685 }
1686 }
1687
1688 bool is_thread_safe() { return true; }
1689 };
1690
1691 void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) {
1692 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
1693 {
1694 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states :
1695 ShenandoahPhaseTimings::degen_gc_final_update_region_states);
1696 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1697 parallel_heap_region_iterate(&cl);
1698
1699 assert_pinned_region_status();
1700 }
1701
1702 {
1703 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset :
1704 ShenandoahPhaseTimings::degen_gc_choose_cset);
1705 ShenandoahHeapLocker locker(lock());
1706 _collection_set->clear();
1707 heuristics()->choose_collection_set(_collection_set);
1708 }
1709
1710 {
1711 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset :
1712 ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset);
1713 ShenandoahHeapLocker locker(lock());
1714 _free_set->rebuild();
1715 }
1716 }
1717
1718 void ShenandoahHeap::do_class_unloading() {
1719 _unloader.unload();
1720 }
1721
1722 void ShenandoahHeap::stw_weak_refs(bool full_gc) {
1723 // Weak refs processing
1724 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
1725 : ShenandoahPhaseTimings::degen_gc_weakrefs;
1726 ShenandoahTimingsTracker t(phase);
1727 ShenandoahGCWorkerPhase worker_phase(phase);
1728 ref_processor()->process_references(phase, workers(), false /* concurrent */);
1729 }
1730
1731 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
1732 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1733
1734 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
1735 // make them parsable for update code to work correctly. Plus, we can compute new sizes
1736 // for future GCLABs here.
1737 if (UseTLAB) {
1738 ShenandoahGCPhase phase(concurrent ?
1739 ShenandoahPhaseTimings::init_update_refs_manage_gclabs :
1740 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs);
1741 gclabs_retire(ResizeTLAB);
1742 }
1743
1744 _update_refs_iterator.reset();
1745 }
1746
1747 void ShenandoahHeap::set_gc_state_all_threads(char state) {
1748 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1749 ShenandoahThreadLocalData::set_gc_state(t, state);
1750 }
1751 }
1752
1753 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1754 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1755 _gc_state.set_cond(mask, value);
1756 set_gc_state_all_threads(_gc_state.raw_value());
1757 }
1758
1759 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1760 assert(!has_forwarded_objects(), "Not expected before/after mark phase");
1761 set_gc_state_mask(MARKING, in_progress);
1762 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1763 }
1764
1765 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1766 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1767 set_gc_state_mask(EVACUATION, in_progress);
1768 }
1769
1770 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
1771 if (in_progress) {
1772 _concurrent_strong_root_in_progress.set();
1773 } else {
1774 _concurrent_strong_root_in_progress.unset();
1775 }
1776 }
1777
1778 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) {
1779 set_gc_state_mask(WEAK_ROOTS, cond);
1780 }
1781
1782 GCTracer* ShenandoahHeap::tracer() {
1783 return shenandoah_policy()->tracer();
1784 }
1785
1786 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1787 return _free_set->used();
1788 }
1789
1790 bool ShenandoahHeap::try_cancel_gc() {
1791 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1792 return prev == CANCELLABLE;
1793 }
1794
1795 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1796 if (try_cancel_gc()) {
1797 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1798 log_info(gc)("%s", msg.buffer());
1799 Events::log(Thread::current(), "%s", msg.buffer());
1800 }
1801 }
1802
1803 uint ShenandoahHeap::max_workers() {
1804 return _max_workers;
1805 }
1806
1807 void ShenandoahHeap::stop() {
1808 // The shutdown sequence should be able to terminate when GC is running.
1809
1810 // Step 0. Notify policy to disable event recording.
1811 _shenandoah_policy->record_shutdown();
1812
1813 // Step 1. Notify control thread that we are in shutdown.
1814 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1815 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1816 control_thread()->prepare_for_graceful_shutdown();
1817
1818 // Step 2. Notify GC workers that we are cancelling GC.
1819 cancel_gc(GCCause::_shenandoah_stop_vm);
1820
1821 // Step 3. Wait until GC worker exits normally.
1822 control_thread()->stop();
1823 }
1824
1825 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
1826 if (!unload_classes()) return;
1827 // Unload classes and purge SystemDictionary.
1828 {
1829 ShenandoahPhaseTimings::Phase phase = full_gc ?
1830 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1831 ShenandoahPhaseTimings::degen_gc_purge_class_unload;
1832 ShenandoahIsAliveSelector is_alive;
1833 {
1834 CodeCache::UnlinkingScope scope(is_alive.is_alive_closure());
1835 ShenandoahGCPhase gc_phase(phase);
1836 ShenandoahGCWorkerPhase worker_phase(phase);
1837 bool unloading_occurred = SystemDictionary::do_unloading(gc_timer());
1838
1839 uint num_workers = _workers->active_workers();
1840 ShenandoahClassUnloadingTask unlink_task(phase, num_workers, unloading_occurred);
1841 _workers->run_task(&unlink_task);
1842 }
1843 // Release unloaded nmethods's memory.
1844 CodeCache::flush_unlinked_nmethods();
1845 }
1846
1847 {
1848 ShenandoahGCPhase phase(full_gc ?
1849 ShenandoahPhaseTimings::full_gc_purge_cldg :
1850 ShenandoahPhaseTimings::degen_gc_purge_cldg);
1851 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
1852 }
1853 // Resize and verify metaspace
1854 MetaspaceGC::compute_new_size();
1855 DEBUG_ONLY(MetaspaceUtils::verify();)
1856 }
1857
1858 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
1859 // so they should not have forwarded oops.
1860 // However, we do need to "null" dead oops in the roots, if can not be done
1861 // in concurrent cycles.
1862 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
1863 uint num_workers = _workers->active_workers();
1864 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
1865 ShenandoahPhaseTimings::full_gc_purge_weak_par :
1866 ShenandoahPhaseTimings::degen_gc_purge_weak_par;
1867 ShenandoahGCPhase phase(timing_phase);
1868 ShenandoahGCWorkerPhase worker_phase(timing_phase);
1869 // Cleanup weak roots
1870 if (has_forwarded_objects()) {
1871 ShenandoahForwardedIsAliveClosure is_alive;
1872 ShenandoahUpdateRefsClosure keep_alive;
1873 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
1874 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers);
1875 _workers->run_task(&cleaning_task);
1876 } else {
1877 ShenandoahIsAliveClosure is_alive;
1878 #ifdef ASSERT
1879 ShenandoahAssertNotForwardedClosure verify_cl;
1880 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
1881 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers);
1882 #else
1883 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
1884 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers);
1885 #endif
1886 _workers->run_task(&cleaning_task);
1887 }
1888 }
1889
1890 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
1891 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1892 assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC");
1893 ShenandoahGCPhase phase(full_gc ?
1894 ShenandoahPhaseTimings::full_gc_purge :
1895 ShenandoahPhaseTimings::degen_gc_purge);
1896 stw_weak_refs(full_gc);
1897 stw_process_weak_roots(full_gc);
1898 stw_unload_classes(full_gc);
1899 }
1900
1901 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
1902 set_gc_state_mask(HAS_FORWARDED, cond);
1903 }
1904
1905 void ShenandoahHeap::set_unload_classes(bool uc) {
1906 _unload_classes.set_cond(uc);
1907 }
1908
1909 bool ShenandoahHeap::unload_classes() const {
1910 return _unload_classes.is_set();
1911 }
1912
1913 address ShenandoahHeap::in_cset_fast_test_addr() {
1914 ShenandoahHeap* heap = ShenandoahHeap::heap();
1915 assert(heap->collection_set() != nullptr, "Sanity");
1916 return (address) heap->collection_set()->biased_map_address();
1917 }
1918
1919 size_t ShenandoahHeap::bytes_allocated_since_gc_start() const {
1920 return Atomic::load(&_bytes_allocated_since_gc_start);
1921 }
1922
1923 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
1924 Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0);
1925 }
1926
1927 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
1928 _degenerated_gc_in_progress.set_cond(in_progress);
1929 }
1930
1931 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
1932 _full_gc_in_progress.set_cond(in_progress);
1933 }
1934
1935 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
1936 assert (is_full_gc_in_progress(), "should be");
1937 _full_gc_move_in_progress.set_cond(in_progress);
1938 }
1939
1940 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
1941 set_gc_state_mask(UPDATEREFS, in_progress);
1942 }
1943
1944 void ShenandoahHeap::register_nmethod(nmethod* nm) {
1945 ShenandoahCodeRoots::register_nmethod(nm);
1946 }
1947
1948 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
1949 ShenandoahCodeRoots::unregister_nmethod(nm);
1950 }
1951
1952 void ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
1953 heap_region_containing(o)->record_pin();
1954 }
1955
1956 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
1957 ShenandoahHeapRegion* r = heap_region_containing(o);
1958 assert(r != nullptr, "Sanity");
1959 assert(r->pin_count() > 0, "Region " SIZE_FORMAT " should have non-zero pins", r->index());
1960 r->record_unpin();
1961 }
1962
1963 void ShenandoahHeap::sync_pinned_region_status() {
1964 ShenandoahHeapLocker locker(lock());
1965
1966 for (size_t i = 0; i < num_regions(); i++) {
1967 ShenandoahHeapRegion *r = get_region(i);
1968 if (r->is_active()) {
1969 if (r->is_pinned()) {
1970 if (r->pin_count() == 0) {
1971 r->make_unpinned();
1972 }
1973 } else {
1974 if (r->pin_count() > 0) {
1975 r->make_pinned();
1976 }
1977 }
1978 }
1979 }
1980
1981 assert_pinned_region_status();
1982 }
1983
1984 #ifdef ASSERT
1985 void ShenandoahHeap::assert_pinned_region_status() {
1986 for (size_t i = 0; i < num_regions(); i++) {
1987 ShenandoahHeapRegion* r = get_region(i);
1988 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
1989 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
1990 }
1991 }
1992 #endif
1993
1994 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
1995 return _gc_timer;
1996 }
1997
1998 void ShenandoahHeap::prepare_concurrent_roots() {
1999 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2000 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
2001 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
2002 set_concurrent_weak_root_in_progress(true);
2003 if (unload_classes()) {
2004 _unloader.prepare();
2005 }
2006 }
2007
2008 void ShenandoahHeap::finish_concurrent_roots() {
2009 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2010 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
2011 if (unload_classes()) {
2012 _unloader.finish();
2013 }
2014 }
2015
2016 #ifdef ASSERT
2017 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2018 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2019
2020 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2021 if (UseDynamicNumberOfGCThreads) {
2022 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2023 } else {
2024 // Use ParallelGCThreads inside safepoints
2025 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
2026 }
2027 } else {
2028 if (UseDynamicNumberOfGCThreads) {
2029 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2030 } else {
2031 // Use ConcGCThreads outside safepoints
2032 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2033 }
2034 }
2035 }
2036 #endif
2037
2038 ShenandoahVerifier* ShenandoahHeap::verifier() {
2039 guarantee(ShenandoahVerify, "Should be enabled");
2040 assert (_verifier != nullptr, "sanity");
2041 return _verifier;
2042 }
2043
2044 template<bool CONCURRENT>
2045 class ShenandoahUpdateHeapRefsTask : public WorkerTask {
2046 private:
2047 ShenandoahHeap* _heap;
2048 ShenandoahRegionIterator* _regions;
2049 public:
2050 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
2051 WorkerTask("Shenandoah Update References"),
2052 _heap(ShenandoahHeap::heap()),
2053 _regions(regions) {
2054 }
2055
2056 void work(uint worker_id) {
2057 if (CONCURRENT) {
2058 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2059 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2060 do_work<ShenandoahConcUpdateRefsClosure>();
2061 } else {
2062 ShenandoahParallelWorkerSession worker_session(worker_id);
2063 do_work<ShenandoahSTWUpdateRefsClosure>();
2064 }
2065 }
2066
2067 private:
2068 template<class T>
2069 void do_work() {
2070 T cl;
2071 ShenandoahHeapRegion* r = _regions->next();
2072 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2073 while (r != nullptr) {
2074 HeapWord* update_watermark = r->get_update_watermark();
2075 assert (update_watermark >= r->bottom(), "sanity");
2076 if (r->is_active() && !r->is_cset()) {
2077 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2078 }
2079 if (ShenandoahPacing) {
2080 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2081 }
2082 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2083 return;
2084 }
2085 r = _regions->next();
2086 }
2087 }
2088 };
2089
2090 void ShenandoahHeap::update_heap_references(bool concurrent) {
2091 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2092
2093 if (concurrent) {
2094 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator);
2095 workers()->run_task(&task);
2096 } else {
2097 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
2098 workers()->run_task(&task);
2099 }
2100 }
2101
2102
2103 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2104 private:
2105 ShenandoahHeapLock* const _lock;
2106
2107 public:
2108 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2109
2110 void heap_region_do(ShenandoahHeapRegion* r) {
2111 // Drop unnecessary "pinned" state from regions that does not have CP marks
2112 // anymore, as this would allow trashing them.
2113
2114 if (r->is_active()) {
2115 if (r->is_pinned()) {
2116 if (r->pin_count() == 0) {
2117 ShenandoahHeapLocker locker(_lock);
2118 r->make_unpinned();
2119 }
2120 } else {
2121 if (r->pin_count() > 0) {
2122 ShenandoahHeapLocker locker(_lock);
2123 r->make_pinned();
2124 }
2125 }
2126 }
2127 }
2128
2129 bool is_thread_safe() { return true; }
2130 };
2131
2132 void ShenandoahHeap::update_heap_region_states(bool concurrent) {
2133 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2134 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2135
2136 {
2137 ShenandoahGCPhase phase(concurrent ?
2138 ShenandoahPhaseTimings::final_update_refs_update_region_states :
2139 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states);
2140 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2141 parallel_heap_region_iterate(&cl);
2142
2143 assert_pinned_region_status();
2144 }
2145
2146 {
2147 ShenandoahGCPhase phase(concurrent ?
2148 ShenandoahPhaseTimings::final_update_refs_trash_cset :
2149 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset);
2150 trash_cset_regions();
2151 }
2152 }
2153
2154 void ShenandoahHeap::rebuild_free_set(bool concurrent) {
2155 {
2156 ShenandoahGCPhase phase(concurrent ?
2157 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
2158 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
2159 ShenandoahHeapLocker locker(lock());
2160 _free_set->rebuild();
2161 }
2162 }
2163
2164 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2165 print_on(st);
2166 st->cr();
2167 print_heap_regions_on(st);
2168 }
2169
2170 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2171 size_t slice = r->index() / _bitmap_regions_per_slice;
2172
2173 size_t regions_from = _bitmap_regions_per_slice * slice;
2174 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2175 for (size_t g = regions_from; g < regions_to; g++) {
2176 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2177 if (skip_self && g == r->index()) continue;
2178 if (get_region(g)->is_committed()) {
2179 return true;
2180 }
2181 }
2182 return false;
2183 }
2184
2185 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2186 shenandoah_assert_heaplocked();
2187
2188 // Bitmaps in special regions do not need commits
2189 if (_bitmap_region_special) {
2190 return true;
2191 }
2192
2193 if (is_bitmap_slice_committed(r, true)) {
2194 // Some other region from the group is already committed, meaning the bitmap
2195 // slice is already committed, we exit right away.
2196 return true;
2197 }
2198
2199 // Commit the bitmap slice:
2200 size_t slice = r->index() / _bitmap_regions_per_slice;
2201 size_t off = _bitmap_bytes_per_slice * slice;
2202 size_t len = _bitmap_bytes_per_slice;
2203 char* start = (char*) _bitmap_region.start() + off;
2204
2205 if (!os::commit_memory(start, len, false)) {
2206 return false;
2207 }
2208
2209 if (AlwaysPreTouch) {
2210 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size);
2211 }
2212
2213 return true;
2214 }
2215
2216 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2217 shenandoah_assert_heaplocked();
2218
2219 // Bitmaps in special regions do not need uncommits
2220 if (_bitmap_region_special) {
2221 return true;
2222 }
2223
2224 if (is_bitmap_slice_committed(r, true)) {
2225 // Some other region from the group is still committed, meaning the bitmap
2226 // slice is should stay committed, exit right away.
2227 return true;
2228 }
2229
2230 // Uncommit the bitmap slice:
2231 size_t slice = r->index() / _bitmap_regions_per_slice;
2232 size_t off = _bitmap_bytes_per_slice * slice;
2233 size_t len = _bitmap_bytes_per_slice;
2234 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2235 return false;
2236 }
2237 return true;
2238 }
2239
2240 void ShenandoahHeap::safepoint_synchronize_begin() {
2241 if (ShenandoahSuspendibleWorkers) {
2242 SuspendibleThreadSet::synchronize();
2243 }
2244 }
2245
2246 void ShenandoahHeap::safepoint_synchronize_end() {
2247 if (ShenandoahSuspendibleWorkers) {
2248 SuspendibleThreadSet::desynchronize();
2249 }
2250 }
2251
2252 void ShenandoahHeap::entry_uncommit(double shrink_before, size_t shrink_until) {
2253 static const char *msg = "Concurrent uncommit";
2254 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
2255 EventMark em("%s", msg);
2256
2257 op_uncommit(shrink_before, shrink_until);
2258 }
2259
2260 void ShenandoahHeap::try_inject_alloc_failure() {
2261 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2262 _inject_alloc_failure.set();
2263 os::naked_short_sleep(1);
2264 if (cancelled_gc()) {
2265 log_info(gc)("Allocation failure was successfully injected");
2266 }
2267 }
2268 }
2269
2270 bool ShenandoahHeap::should_inject_alloc_failure() {
2271 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2272 }
2273
2274 void ShenandoahHeap::initialize_serviceability() {
2275 _memory_pool = new ShenandoahMemoryPool(this);
2276 _cycle_memory_manager.add_pool(_memory_pool);
2277 _stw_memory_manager.add_pool(_memory_pool);
2278 }
2279
2280 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2281 GrowableArray<GCMemoryManager*> memory_managers(2);
2282 memory_managers.append(&_cycle_memory_manager);
2283 memory_managers.append(&_stw_memory_manager);
2284 return memory_managers;
2285 }
2286
2287 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2288 GrowableArray<MemoryPool*> memory_pools(1);
2289 memory_pools.append(_memory_pool);
2290 return memory_pools;
2291 }
2292
2293 MemoryUsage ShenandoahHeap::memory_usage() {
2294 return _memory_pool->get_memory_usage();
2295 }
2296
2297 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2298 _heap(ShenandoahHeap::heap()),
2299 _index(0) {}
2300
2301 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2302 _heap(heap),
2303 _index(0) {}
2304
2305 void ShenandoahRegionIterator::reset() {
2306 _index = 0;
2307 }
2308
2309 bool ShenandoahRegionIterator::has_next() const {
2310 return _index < _heap->num_regions();
2311 }
2312
2313 char ShenandoahHeap::gc_state() const {
2314 return _gc_state.raw_value();
2315 }
2316
2317 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2318 #ifdef ASSERT
2319 assert(_liveness_cache != nullptr, "sanity");
2320 assert(worker_id < _max_workers, "sanity");
2321 for (uint i = 0; i < num_regions(); i++) {
2322 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2323 }
2324 #endif
2325 return _liveness_cache[worker_id];
2326 }
2327
2328 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2329 assert(worker_id < _max_workers, "sanity");
2330 assert(_liveness_cache != nullptr, "sanity");
2331 ShenandoahLiveData* ld = _liveness_cache[worker_id];
2332 for (uint i = 0; i < num_regions(); i++) {
2333 ShenandoahLiveData live = ld[i];
2334 if (live > 0) {
2335 ShenandoahHeapRegion* r = get_region(i);
2336 r->increase_live_data_gc_words(live);
2337 ld[i] = 0;
2338 }
2339 }
2340 }
2341
2342 bool ShenandoahHeap::requires_barriers(stackChunkOop obj) const {
2343 if (is_idle()) return false;
2344
2345 // Objects allocated after marking start are implicitly alive, don't need any barriers during
2346 // marking phase.
2347 if (is_concurrent_mark_in_progress() &&
2348 !marking_context()->allocated_after_mark_start(obj)) {
2349 return true;
2350 }
2351
2352 // Can not guarantee obj is deeply good.
2353 if (has_forwarded_objects()) {
2354 return true;
2355 }
2356
2357 return false;
2358 }