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/slidingForwarding.hpp"
37 #include "gc/shared/tlab_globals.hpp"
38
39 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
40 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
41 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
42 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
43 #include "gc/shenandoah/shenandoahConcurrentMark.hpp"
44 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
45 #include "gc/shenandoah/shenandoahControlThread.hpp"
46 #include "gc/shenandoah/shenandoahFreeSet.hpp"
47 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
48 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
49 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
50 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
51 #include "gc/shenandoah/shenandoahInitLogger.hpp"
52 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
53 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
54 #include "gc/shenandoah/shenandoahMetrics.hpp"
55 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
56 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
57 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
58 #include "gc/shenandoah/shenandoahPadding.hpp"
59 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
60 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
61 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
62 #include "gc/shenandoah/shenandoahSTWMark.hpp"
63 #include "gc/shenandoah/shenandoahUtils.hpp"
64 #include "gc/shenandoah/shenandoahVerifier.hpp"
65 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
66 #include "gc/shenandoah/shenandoahVMOperations.hpp"
67 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
68 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
69 #include "gc/shenandoah/mode/shenandoahIUMode.hpp"
70 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
71 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
72 #if INCLUDE_JFR
73 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
74 #endif
75
76 #include "classfile/systemDictionary.hpp"
77 #include "code/codeCache.hpp"
78 #include "memory/classLoaderMetaspace.hpp"
79 #include "memory/metaspaceUtils.hpp"
80 #include "nmt/mallocTracker.hpp"
81 #include "nmt/memTracker.hpp"
82 #include "oops/compressedOops.inline.hpp"
83 #include "prims/jvmtiTagMap.hpp"
84 #include "runtime/atomic.hpp"
85 #include "runtime/globals.hpp"
86 #include "runtime/interfaceSupport.inline.hpp"
87 #include "runtime/java.hpp"
88 #include "runtime/orderAccess.hpp"
89 #include "runtime/safepointMechanism.hpp"
90 #include "runtime/vmThread.hpp"
91 #include "utilities/events.hpp"
92 #include "utilities/powerOfTwo.hpp"
93
94 class ShenandoahPretouchHeapTask : public WorkerTask {
95 private:
96 ShenandoahRegionIterator _regions;
97 const size_t _page_size;
98 public:
99 ShenandoahPretouchHeapTask(size_t page_size) :
100 WorkerTask("Shenandoah Pretouch Heap"),
101 _page_size(page_size) {}
102
103 virtual void work(uint worker_id) {
104 ShenandoahHeapRegion* r = _regions.next();
105 while (r != nullptr) {
106 if (r->is_committed()) {
107 os::pretouch_memory(r->bottom(), r->end(), _page_size);
108 }
109 r = _regions.next();
110 }
111 }
112 };
113
114 class ShenandoahPretouchBitmapTask : public WorkerTask {
115 private:
116 ShenandoahRegionIterator _regions;
117 char* _bitmap_base;
118 const size_t _bitmap_size;
119 const size_t _page_size;
120 public:
121 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
122 WorkerTask("Shenandoah Pretouch Bitmap"),
123 _bitmap_base(bitmap_base),
124 _bitmap_size(bitmap_size),
125 _page_size(page_size) {}
126
127 virtual void work(uint worker_id) {
128 ShenandoahHeapRegion* r = _regions.next();
129 while (r != nullptr) {
130 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
131 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
132 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
133
134 if (r->is_committed()) {
135 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
136 }
137
138 r = _regions.next();
139 }
140 }
141 };
142
143 jint ShenandoahHeap::initialize() {
144 //
145 // Figure out heap sizing
146 //
147
148 size_t init_byte_size = InitialHeapSize;
149 size_t min_byte_size = MinHeapSize;
150 size_t max_byte_size = MaxHeapSize;
151 size_t heap_alignment = HeapAlignment;
152
153 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
154
155 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
156 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
157
158 _num_regions = ShenandoahHeapRegion::region_count();
159 assert(_num_regions == (max_byte_size / reg_size_bytes),
160 "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT,
161 _num_regions, max_byte_size, reg_size_bytes);
162
163 // Now we know the number of regions, initialize the heuristics.
164 initialize_heuristics();
165
166 size_t num_committed_regions = init_byte_size / reg_size_bytes;
167 num_committed_regions = MIN2(num_committed_regions, _num_regions);
168 assert(num_committed_regions <= _num_regions, "sanity");
169 _initial_size = num_committed_regions * reg_size_bytes;
170
171 size_t num_min_regions = min_byte_size / reg_size_bytes;
172 num_min_regions = MIN2(num_min_regions, _num_regions);
173 assert(num_min_regions <= _num_regions, "sanity");
174 _minimum_size = num_min_regions * reg_size_bytes;
175
176 // Default to max heap size.
177 _soft_max_size = _num_regions * reg_size_bytes;
178
179 _committed = _initial_size;
180
181 size_t heap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
182 size_t bitmap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
183 size_t region_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
184
185 //
186 // Reserve and commit memory for heap
187 //
188
189 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
190 initialize_reserved_region(heap_rs);
191 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
192 _heap_region_special = heap_rs.special();
193
194 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
195 "Misaligned heap: " PTR_FORMAT, p2i(base()));
196 os::trace_page_sizes_for_requested_size("Heap",
197 max_byte_size, heap_alignment,
198 heap_rs.base(),
199 heap_rs.size(), heap_rs.page_size());
200
201 #if SHENANDOAH_OPTIMIZED_MARKTASK
202 // The optimized ShenandoahMarkTask takes some bits away from the full object bits.
203 // Fail if we ever attempt to address more than we can.
204 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) {
205 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
206 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
207 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
208 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable());
209 vm_exit_during_initialization("Fatal Error", buf);
210 }
211 #endif
212
213 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
214 if (!_heap_region_special) {
215 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
216 "Cannot commit heap memory");
217 }
218
219 //
220 // Reserve and commit memory for bitmap(s)
221 //
222
223 size_t bitmap_size_orig = ShenandoahMarkBitMap::compute_size(heap_rs.size());
224 _bitmap_size = align_up(bitmap_size_orig, bitmap_page_size);
225
226 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor();
227
228 guarantee(bitmap_bytes_per_region != 0,
229 "Bitmap bytes per region should not be zero");
230 guarantee(is_power_of_2(bitmap_bytes_per_region),
231 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
232
233 if (bitmap_page_size > bitmap_bytes_per_region) {
234 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
235 _bitmap_bytes_per_slice = bitmap_page_size;
236 } else {
237 _bitmap_regions_per_slice = 1;
238 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
239 }
240
241 guarantee(_bitmap_regions_per_slice >= 1,
242 "Should have at least one region per slice: " SIZE_FORMAT,
243 _bitmap_regions_per_slice);
244
245 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
246 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
247 _bitmap_bytes_per_slice, bitmap_page_size);
248
249 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
250 os::trace_page_sizes_for_requested_size("Mark Bitmap",
251 bitmap_size_orig, bitmap_page_size,
252 bitmap.base(),
253 bitmap.size(), bitmap.page_size());
254 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
255 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
256 _bitmap_region_special = bitmap.special();
257
258 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
259 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
260 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
261 if (!_bitmap_region_special) {
262 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
263 "Cannot commit bitmap memory");
264 }
265
266 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions, _max_workers);
267
268 if (ShenandoahVerify) {
269 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
270 os::trace_page_sizes_for_requested_size("Verify Bitmap",
271 bitmap_size_orig, bitmap_page_size,
272 verify_bitmap.base(),
273 verify_bitmap.size(), verify_bitmap.page_size());
274 if (!verify_bitmap.special()) {
275 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
276 "Cannot commit verification bitmap memory");
277 }
278 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
279 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
280 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
281 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
282 }
283
284 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
285 size_t aux_bitmap_page_size = bitmap_page_size;
286 #ifdef LINUX
287 // In THP "advise" mode, we refrain from advising the system to use large pages
288 // since we know these commits will be short lived, and there is no reason to trash
289 // the THP area with this bitmap.
290 if (UseTransparentHugePages) {
291 aux_bitmap_page_size = os::vm_page_size();
292 }
293 #endif
294 ReservedSpace aux_bitmap(_bitmap_size, aux_bitmap_page_size);
295 os::trace_page_sizes_for_requested_size("Aux Bitmap",
296 bitmap_size_orig, aux_bitmap_page_size,
297 aux_bitmap.base(),
298 aux_bitmap.size(), aux_bitmap.page_size());
299 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
300 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
301 _aux_bitmap_region_special = aux_bitmap.special();
302 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
303
304 //
305 // Create regions and region sets
306 //
307 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
308 size_t region_storage_size_orig = region_align * _num_regions;
309 size_t region_storage_size = align_up(region_storage_size_orig,
310 MAX2(region_page_size, os::vm_allocation_granularity()));
311
312 ReservedSpace region_storage(region_storage_size, region_page_size);
313 os::trace_page_sizes_for_requested_size("Region Storage",
314 region_storage_size_orig, region_page_size,
315 region_storage.base(),
316 region_storage.size(), region_storage.page_size());
317 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
318 if (!region_storage.special()) {
319 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
320 "Cannot commit region memory");
321 }
322
323 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks.
324 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there.
325 // If not successful, bite a bullet and allocate at whatever address.
326 {
327 const size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
328 const size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align);
329 const size_t cset_page_size = os::vm_page_size();
330
331 uintptr_t min = round_up_power_of_2(cset_align);
332 uintptr_t max = (1u << 30u);
333 ReservedSpace cset_rs;
334
335 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
336 char* req_addr = (char*)addr;
337 assert(is_aligned(req_addr, cset_align), "Should be aligned");
338 cset_rs = ReservedSpace(cset_size, cset_align, cset_page_size, req_addr);
339 if (cset_rs.is_reserved()) {
340 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr);
341 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
342 break;
343 }
344 }
345
346 if (_collection_set == nullptr) {
347 cset_rs = ReservedSpace(cset_size, cset_align, os::vm_page_size());
348 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
349 }
350 os::trace_page_sizes_for_requested_size("Collection Set",
351 cset_size, cset_page_size,
352 cset_rs.base(),
353 cset_rs.size(), cset_rs.page_size());
354 }
355
356 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
357 _free_set = new ShenandoahFreeSet(this, _num_regions);
358
359 {
360 ShenandoahHeapLocker locker(lock());
361
362 for (size_t i = 0; i < _num_regions; i++) {
363 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
364 bool is_committed = i < num_committed_regions;
365 void* loc = region_storage.base() + i * region_align;
366
367 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
368 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
369
370 _marking_context->initialize_top_at_mark_start(r);
371 _regions[i] = r;
372 assert(!collection_set()->is_in(i), "New region should not be in collection set");
373 }
374
375 // Initialize to complete
376 _marking_context->mark_complete();
377
378 _free_set->rebuild();
379 }
380
381 if (AlwaysPreTouch) {
382 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
383 // before initialize() below zeroes it with initializing thread. For any given region,
384 // we touch the region and the corresponding bitmaps from the same thread.
385 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
386
387 _pretouch_heap_page_size = heap_page_size;
388 _pretouch_bitmap_page_size = bitmap_page_size;
389
390 #ifdef LINUX
391 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
392 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
393 // them into huge one. Therefore, we need to pretouch with smaller pages.
394 if (UseTransparentHugePages) {
395 _pretouch_heap_page_size = (size_t)os::vm_page_size();
396 _pretouch_bitmap_page_size = (size_t)os::vm_page_size();
397 }
398 #endif
399
400 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
401 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
402
403 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size);
404 _workers->run_task(&bcl);
405
406 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size);
407 _workers->run_task(&hcl);
408 }
409
410 //
411 // Initialize the rest of GC subsystems
412 //
413
414 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
415 for (uint worker = 0; worker < _max_workers; worker++) {
416 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
417 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
418 }
419
420 // There should probably be Shenandoah-specific options for these,
421 // just as there are G1-specific options.
422 {
423 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
424 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
425 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
426 }
427
428 _monitoring_support = new ShenandoahMonitoringSupport(this);
429 _phase_timings = new ShenandoahPhaseTimings(max_workers());
430 ShenandoahCodeRoots::initialize();
431
432 if (ShenandoahPacing) {
433 _pacer = new ShenandoahPacer(this);
434 _pacer->setup_for_idle();
435 } else {
436 _pacer = nullptr;
437 }
438
439 _control_thread = new ShenandoahControlThread();
440
441 ShenandoahInitLogger::print();
442
443 SlidingForwarding::initialize(_heap_region, ShenandoahHeapRegion::region_size_words());
444
445 return JNI_OK;
446 }
447
448 void ShenandoahHeap::initialize_mode() {
449 if (ShenandoahGCMode != nullptr) {
450 if (strcmp(ShenandoahGCMode, "satb") == 0) {
451 _gc_mode = new ShenandoahSATBMode();
452 } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
453 _gc_mode = new ShenandoahIUMode();
454 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
455 _gc_mode = new ShenandoahPassiveMode();
456 } else {
457 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
458 }
459 } else {
460 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option (null)");
461 }
462 _gc_mode->initialize_flags();
463 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
464 vm_exit_during_initialization(
465 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
466 _gc_mode->name()));
467 }
468 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
469 vm_exit_during_initialization(
470 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
471 _gc_mode->name()));
472 }
473 }
474
475 void ShenandoahHeap::initialize_heuristics() {
476 assert(_gc_mode != nullptr, "Must be initialized");
477 _heuristics = _gc_mode->initialize_heuristics();
478
479 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
480 vm_exit_during_initialization(
481 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
482 _heuristics->name()));
483 }
484 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
485 vm_exit_during_initialization(
486 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
487 _heuristics->name()));
488 }
489 }
490
491 #ifdef _MSC_VER
492 #pragma warning( push )
493 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
494 #endif
495
496 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
497 CollectedHeap(),
498 _initial_size(0),
499 _used(0),
500 _committed(0),
501 _bytes_allocated_since_gc_start(0),
502 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
503 _workers(nullptr),
504 _safepoint_workers(nullptr),
505 _heap_region_special(false),
506 _num_regions(0),
507 _regions(nullptr),
508 _update_refs_iterator(this),
509 _gc_no_progress_count(0),
510 _control_thread(nullptr),
511 _shenandoah_policy(policy),
512 _gc_mode(nullptr),
513 _heuristics(nullptr),
514 _free_set(nullptr),
515 _pacer(nullptr),
516 _verifier(nullptr),
517 _phase_timings(nullptr),
518 _monitoring_support(nullptr),
519 _memory_pool(nullptr),
520 _stw_memory_manager("Shenandoah Pauses"),
521 _cycle_memory_manager("Shenandoah Cycles"),
522 _gc_timer(new ConcurrentGCTimer()),
523 _soft_ref_policy(),
524 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
525 _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))),
526 _marking_context(nullptr),
527 _bitmap_size(0),
528 _bitmap_regions_per_slice(0),
529 _bitmap_bytes_per_slice(0),
530 _bitmap_region_special(false),
531 _aux_bitmap_region_special(false),
532 _liveness_cache(nullptr),
533 _collection_set(nullptr)
534 {
535 // Initialize GC mode early, so we can adjust barrier support
536 initialize_mode();
537 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
538
539 _max_workers = MAX2(_max_workers, 1U);
540 _workers = new ShenandoahWorkerThreads("Shenandoah GC Threads", _max_workers);
541 if (_workers == nullptr) {
542 vm_exit_during_initialization("Failed necessary allocation.");
543 } else {
544 _workers->initialize_workers();
545 }
546
547 if (ParallelGCThreads > 1) {
548 _safepoint_workers = new ShenandoahWorkerThreads("Safepoint Cleanup Thread",
549 ParallelGCThreads);
550 _safepoint_workers->initialize_workers();
551 }
552 }
553
554 #ifdef _MSC_VER
555 #pragma warning( pop )
556 #endif
557
558 class ShenandoahResetBitmapTask : public WorkerTask {
559 private:
560 ShenandoahRegionIterator _regions;
561
562 public:
563 ShenandoahResetBitmapTask() :
564 WorkerTask("Shenandoah Reset Bitmap") {}
565
566 void work(uint worker_id) {
567 ShenandoahHeapRegion* region = _regions.next();
568 ShenandoahHeap* heap = ShenandoahHeap::heap();
569 ShenandoahMarkingContext* const ctx = heap->marking_context();
570 while (region != nullptr) {
571 if (heap->is_bitmap_slice_committed(region)) {
572 ctx->clear_bitmap(region);
573 }
574 region = _regions.next();
575 }
576 }
577 };
578
579 void ShenandoahHeap::reset_mark_bitmap() {
580 assert_gc_workers(_workers->active_workers());
581 mark_incomplete_marking_context();
582
583 ShenandoahResetBitmapTask task;
584 _workers->run_task(&task);
585 }
586
587 void ShenandoahHeap::print_on(outputStream* st) const {
588 st->print_cr("Shenandoah Heap");
589 st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
590 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
591 byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
592 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
593 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
594 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
595 num_regions(),
596 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
597 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
598
599 st->print("Status: ");
600 if (has_forwarded_objects()) st->print("has forwarded objects, ");
601 if (is_concurrent_mark_in_progress()) st->print("marking, ");
602 if (is_evacuation_in_progress()) st->print("evacuating, ");
603 if (is_update_refs_in_progress()) st->print("updating refs, ");
604 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
605 if (is_full_gc_in_progress()) st->print("full gc, ");
606 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
607 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
608 if (is_concurrent_strong_root_in_progress() &&
609 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
610
611 if (cancelled_gc()) {
612 st->print("cancelled");
613 } else {
614 st->print("not cancelled");
615 }
616 st->cr();
617
618 st->print_cr("Reserved region:");
619 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
620 p2i(reserved_region().start()),
621 p2i(reserved_region().end()));
622
623 ShenandoahCollectionSet* cset = collection_set();
624 st->print_cr("Collection set:");
625 if (cset != nullptr) {
626 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
627 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
628 } else {
629 st->print_cr(" (null)");
630 }
631
632 st->cr();
633 MetaspaceUtils::print_on(st);
634
635 if (Verbose) {
636 st->cr();
637 print_heap_regions_on(st);
638 }
639 }
640
641 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
642 public:
643 void do_thread(Thread* thread) {
644 assert(thread != nullptr, "Sanity");
645 assert(thread->is_Worker_thread(), "Only worker thread expected");
646 ShenandoahThreadLocalData::initialize_gclab(thread);
647 }
648 };
649
650 void ShenandoahHeap::post_initialize() {
651 CollectedHeap::post_initialize();
652 MutexLocker ml(Threads_lock);
653
654 ShenandoahInitWorkerGCLABClosure init_gclabs;
655 _workers->threads_do(&init_gclabs);
656
657 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
658 // Now, we will let WorkerThreads to initialize gclab when new worker is created.
659 _workers->set_initialize_gclab();
660 if (_safepoint_workers != nullptr) {
661 _safepoint_workers->threads_do(&init_gclabs);
662 _safepoint_workers->set_initialize_gclab();
663 }
664
665 _heuristics->initialize();
666
667 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
668 }
669
670 size_t ShenandoahHeap::used() const {
671 return Atomic::load(&_used);
672 }
673
674 size_t ShenandoahHeap::committed() const {
675 return Atomic::load(&_committed);
676 }
677
678 size_t ShenandoahHeap::available() const {
679 return free_set()->available();
680 }
681
682 void ShenandoahHeap::increase_committed(size_t bytes) {
683 shenandoah_assert_heaplocked_or_safepoint();
684 _committed += bytes;
685 }
686
687 void ShenandoahHeap::decrease_committed(size_t bytes) {
688 shenandoah_assert_heaplocked_or_safepoint();
689 _committed -= bytes;
690 }
691
692 void ShenandoahHeap::increase_used(size_t bytes) {
693 Atomic::add(&_used, bytes, memory_order_relaxed);
694 }
695
696 void ShenandoahHeap::set_used(size_t bytes) {
697 Atomic::store(&_used, bytes);
698 }
699
700 void ShenandoahHeap::decrease_used(size_t bytes) {
701 assert(used() >= bytes, "never decrease heap size by more than we've left");
702 Atomic::sub(&_used, bytes, memory_order_relaxed);
703 }
704
705 void ShenandoahHeap::increase_allocated(size_t bytes) {
706 Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed);
707 }
708
709 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
710 size_t bytes = words * HeapWordSize;
711 if (!waste) {
712 increase_used(bytes);
713 }
714 increase_allocated(bytes);
715 if (ShenandoahPacing) {
716 control_thread()->pacing_notify_alloc(words);
717 if (waste) {
718 pacer()->claim_for_alloc(words, true);
719 }
720 }
721 }
722
723 size_t ShenandoahHeap::capacity() const {
724 return committed();
725 }
726
727 size_t ShenandoahHeap::max_capacity() const {
728 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
729 }
730
731 size_t ShenandoahHeap::soft_max_capacity() const {
732 size_t v = Atomic::load(&_soft_max_size);
733 assert(min_capacity() <= v && v <= max_capacity(),
734 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
735 min_capacity(), v, max_capacity());
736 return v;
737 }
738
739 void ShenandoahHeap::set_soft_max_capacity(size_t v) {
740 assert(min_capacity() <= v && v <= max_capacity(),
741 "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
742 min_capacity(), v, max_capacity());
743 Atomic::store(&_soft_max_size, v);
744 }
745
746 size_t ShenandoahHeap::min_capacity() const {
747 return _minimum_size;
748 }
749
750 size_t ShenandoahHeap::initial_capacity() const {
751 return _initial_size;
752 }
753
754 bool ShenandoahHeap::is_in(const void* p) const {
755 HeapWord* heap_base = (HeapWord*) base();
756 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
757 return p >= heap_base && p < last_region_end;
758 }
759
760 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
761 assert (ShenandoahUncommit, "should be enabled");
762
763 // Application allocates from the beginning of the heap, and GC allocates at
764 // the end of it. It is more efficient to uncommit from the end, so that applications
765 // could enjoy the near committed regions. GC allocations are much less frequent,
766 // and therefore can accept the committing costs.
767
768 size_t count = 0;
769 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
770 ShenandoahHeapRegion* r = get_region(i - 1);
771 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
772 ShenandoahHeapLocker locker(lock());
773 if (r->is_empty_committed()) {
774 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
775 break;
776 }
777
778 r->make_uncommitted();
779 count++;
780 }
781 }
782 SpinPause(); // allow allocators to take the lock
783 }
784
785 if (count > 0) {
786 control_thread()->notify_heap_changed();
787 }
788 }
789
790 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
791 // New object should fit the GCLAB size
792 size_t min_size = MAX2(size, PLAB::min_size());
793
794 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
795 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
796 new_size = MIN2(new_size, PLAB::max_size());
797 new_size = MAX2(new_size, PLAB::min_size());
798
799 // Record new heuristic value even if we take any shortcut. This captures
800 // the case when moderately-sized objects always take a shortcut. At some point,
801 // heuristics should catch up with them.
802 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
803
804 if (new_size < size) {
805 // New size still does not fit the object. Fall back to shared allocation.
806 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
807 return nullptr;
808 }
809
810 // Retire current GCLAB, and allocate a new one.
811 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
812 gclab->retire();
813
814 size_t actual_size = 0;
815 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
816 if (gclab_buf == nullptr) {
817 return nullptr;
818 }
819
820 assert (size <= actual_size, "allocation should fit");
821
822 if (ZeroTLAB) {
823 // ..and clear it.
824 Copy::zero_to_words(gclab_buf, actual_size);
825 } else {
826 // ...and zap just allocated object.
827 #ifdef ASSERT
828 // Skip mangling the space corresponding to the object header to
829 // ensure that the returned space is not considered parsable by
830 // any concurrent GC thread.
831 size_t hdr_size = oopDesc::header_size();
832 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
833 #endif // ASSERT
834 }
835 gclab->set_buf(gclab_buf, actual_size);
836 return gclab->allocate(size);
837 }
838
839 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
840 size_t requested_size,
841 size_t* actual_size) {
842 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
843 HeapWord* res = allocate_memory(req);
844 if (res != nullptr) {
845 *actual_size = req.actual_size();
846 } else {
847 *actual_size = 0;
848 }
849 return res;
850 }
851
852 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
853 size_t word_size,
854 size_t* actual_size) {
855 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
856 HeapWord* res = allocate_memory(req);
857 if (res != nullptr) {
858 *actual_size = req.actual_size();
859 } else {
860 *actual_size = 0;
861 }
862 return res;
863 }
864
865 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
866 intptr_t pacer_epoch = 0;
867 bool in_new_region = false;
868 HeapWord* result = nullptr;
869
870 if (req.is_mutator_alloc()) {
871 if (ShenandoahPacing) {
872 pacer()->pace_for_alloc(req.size());
873 pacer_epoch = pacer()->epoch();
874 }
875
876 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
877 result = allocate_memory_under_lock(req, in_new_region);
878 }
879
880 // Check that gc overhead is not exceeded.
881 //
882 // Shenandoah will grind along for quite a while allocating one
883 // object at a time using shared (non-tlab) allocations. This check
884 // is testing that the GC overhead limit has not been exceeded.
885 // This will notify the collector to start a cycle, but will raise
886 // an OOME to the mutator if the last Full GCs have not made progress.
887 if (result == nullptr && !req.is_lab_alloc() && get_gc_no_progress_count() > ShenandoahNoProgressThreshold) {
888 control_thread()->handle_alloc_failure(req, false);
889 return nullptr;
890 }
891
892 // Block until control thread reacted, then retry allocation.
893 //
894 // It might happen that one of the threads requesting allocation would unblock
895 // way later after GC happened, only to fail the second allocation, because
896 // other threads have already depleted the free storage. In this case, a better
897 // strategy is to try again, as long as GC makes progress (or until at least
898 // one full GC has completed).
899 size_t original_count = shenandoah_policy()->full_gc_count();
900 while (result == nullptr
901 && (get_gc_no_progress_count() == 0 || original_count == shenandoah_policy()->full_gc_count())) {
902 control_thread()->handle_alloc_failure(req);
903 result = allocate_memory_under_lock(req, in_new_region);
904 }
905
906 if (log_is_enabled(Debug, gc, alloc)) {
907 ResourceMark rm;
908 log_debug(gc, alloc)("Thread: %s, Result: " PTR_FORMAT ", Request: %s, Size: " SIZE_FORMAT ", Original: " SIZE_FORMAT ", Latest: " SIZE_FORMAT,
909 Thread::current()->name(), p2i(result), req.type_string(), req.size(), original_count, get_gc_no_progress_count());
910 }
911 } else {
912 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
913 result = allocate_memory_under_lock(req, in_new_region);
914 // Do not call handle_alloc_failure() here, because we cannot block.
915 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
916 }
917
918 if (in_new_region) {
919 control_thread()->notify_heap_changed();
920 }
921
922 if (result != nullptr) {
923 size_t requested = req.size();
924 size_t actual = req.actual_size();
925
926 assert (req.is_lab_alloc() || (requested == actual),
927 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
928 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
929
930 if (req.is_mutator_alloc()) {
931 notify_mutator_alloc_words(actual, false);
932
933 // If we requested more than we were granted, give the rest back to pacer.
934 // This only matters if we are in the same pacing epoch: do not try to unpace
935 // over the budget for the other phase.
936 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
937 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
938 }
939 } else {
940 increase_used(actual*HeapWordSize);
941 }
942 }
943
944 return result;
945 }
946
947 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
948 ShenandoahHeapLocker locker(lock());
949 return _free_set->allocate(req, in_new_region);
950 }
951
952 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
953 bool* gc_overhead_limit_was_exceeded) {
954 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
955 return allocate_memory(req);
956 }
957
958 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
959 size_t size,
960 Metaspace::MetadataType mdtype) {
961 MetaWord* result;
962
963 // Inform metaspace OOM to GC heuristics if class unloading is possible.
964 if (heuristics()->can_unload_classes()) {
965 ShenandoahHeuristics* h = heuristics();
966 h->record_metaspace_oom();
967 }
968
969 // Expand and retry allocation
970 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
971 if (result != nullptr) {
972 return result;
973 }
974
975 // Start full GC
976 collect(GCCause::_metadata_GC_clear_soft_refs);
977
978 // Retry allocation
979 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
980 if (result != nullptr) {
981 return result;
982 }
983
984 // Expand and retry allocation
985 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
986 if (result != nullptr) {
987 return result;
988 }
989
990 // Out of memory
991 return nullptr;
992 }
993
994 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
995 private:
996 ShenandoahHeap* const _heap;
997 Thread* const _thread;
998 public:
999 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
1000 _heap(heap), _thread(Thread::current()) {}
1001
1002 void do_object(oop p) {
1003 shenandoah_assert_marked(nullptr, p);
1004 if (!p->is_forwarded()) {
1005 _heap->evacuate_object(p, _thread);
1006 }
1007 }
1008 };
1009
1010 class ShenandoahEvacuationTask : public WorkerTask {
1011 private:
1012 ShenandoahHeap* const _sh;
1013 ShenandoahCollectionSet* const _cs;
1014 bool _concurrent;
1015 public:
1016 ShenandoahEvacuationTask(ShenandoahHeap* sh,
1017 ShenandoahCollectionSet* cs,
1018 bool concurrent) :
1019 WorkerTask("Shenandoah Evacuation"),
1020 _sh(sh),
1021 _cs(cs),
1022 _concurrent(concurrent)
1023 {}
1024
1025 void work(uint worker_id) {
1026 if (_concurrent) {
1027 ShenandoahConcurrentWorkerSession worker_session(worker_id);
1028 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
1029 ShenandoahEvacOOMScope oom_evac_scope;
1030 do_work();
1031 } else {
1032 ShenandoahParallelWorkerSession worker_session(worker_id);
1033 ShenandoahEvacOOMScope oom_evac_scope;
1034 do_work();
1035 }
1036 }
1037
1038 private:
1039 void do_work() {
1040 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
1041 ShenandoahHeapRegion* r;
1042 while ((r =_cs->claim_next()) != nullptr) {
1043 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
1044 _sh->marked_object_iterate(r, &cl);
1045
1046 if (ShenandoahPacing) {
1047 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
1048 }
1049
1050 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1051 break;
1052 }
1053 }
1054 }
1055 };
1056
1057 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
1058 ShenandoahEvacuationTask task(this, _collection_set, concurrent);
1059 workers()->run_task(&task);
1060 }
1061
1062 void ShenandoahHeap::trash_cset_regions() {
1063 ShenandoahHeapLocker locker(lock());
1064
1065 ShenandoahCollectionSet* set = collection_set();
1066 ShenandoahHeapRegion* r;
1067 set->clear_current_index();
1068 while ((r = set->next()) != nullptr) {
1069 r->make_trash();
1070 }
1071 collection_set()->clear();
1072 }
1073
1074 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1075 st->print_cr("Heap Regions:");
1076 st->print_cr("Region state: EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HP=pinned humongous start");
1077 st->print_cr(" HC=humongous continuation, CS=collection set, TR=trash, P=pinned, CSP=pinned collection set");
1078 st->print_cr("BTE=bottom/top/end, TAMS=top-at-mark-start");
1079 st->print_cr("UWM=update watermark, U=used");
1080 st->print_cr("T=TLAB allocs, G=GCLAB allocs");
1081 st->print_cr("S=shared allocs, L=live data");
1082 st->print_cr("CP=critical pins");
1083
1084 for (size_t i = 0; i < num_regions(); i++) {
1085 get_region(i)->print_on(st);
1086 }
1087 }
1088
1089 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1090 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1091
1092 oop humongous_obj = cast_to_oop(start->bottom());
1093 size_t size = humongous_obj->size();
1094 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1095 size_t index = start->index() + required_regions - 1;
1096
1097 assert(!start->has_live(), "liveness must be zero");
1098
1099 for(size_t i = 0; i < required_regions; i++) {
1100 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1101 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1102 ShenandoahHeapRegion* region = get_region(index --);
1103
1104 assert(region->is_humongous(), "expect correct humongous start or continuation");
1105 assert(!region->is_cset(), "Humongous region should not be in collection set");
1106
1107 region->make_trash_immediate();
1108 }
1109 }
1110
1111 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1112 public:
1113 ShenandoahCheckCleanGCLABClosure() {}
1114 void do_thread(Thread* thread) {
1115 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1116 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1117 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1118 }
1119 };
1120
1121 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1122 private:
1123 bool const _resize;
1124 public:
1125 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1126 void do_thread(Thread* thread) {
1127 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1128 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1129 gclab->retire();
1130 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1131 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1132 }
1133 }
1134 };
1135
1136 void ShenandoahHeap::labs_make_parsable() {
1137 assert(UseTLAB, "Only call with UseTLAB");
1138
1139 ShenandoahRetireGCLABClosure cl(false);
1140
1141 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1142 ThreadLocalAllocBuffer& tlab = t->tlab();
1143 tlab.make_parsable();
1144 cl.do_thread(t);
1145 }
1146
1147 workers()->threads_do(&cl);
1148 }
1149
1150 void ShenandoahHeap::tlabs_retire(bool resize) {
1151 assert(UseTLAB, "Only call with UseTLAB");
1152 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1153
1154 ThreadLocalAllocStats stats;
1155
1156 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1157 ThreadLocalAllocBuffer& tlab = t->tlab();
1158 tlab.retire(&stats);
1159 if (resize) {
1160 tlab.resize();
1161 }
1162 }
1163
1164 stats.publish();
1165
1166 #ifdef ASSERT
1167 ShenandoahCheckCleanGCLABClosure cl;
1168 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1169 cl.do_thread(t);
1170 }
1171 workers()->threads_do(&cl);
1172 #endif
1173 }
1174
1175 void ShenandoahHeap::gclabs_retire(bool resize) {
1176 assert(UseTLAB, "Only call with UseTLAB");
1177 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1178
1179 ShenandoahRetireGCLABClosure cl(resize);
1180 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1181 cl.do_thread(t);
1182 }
1183 workers()->threads_do(&cl);
1184
1185 if (safepoint_workers() != nullptr) {
1186 safepoint_workers()->threads_do(&cl);
1187 }
1188 }
1189
1190 // Returns size in bytes
1191 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1192 if (ShenandoahElasticTLAB) {
1193 // With Elastic TLABs, return the max allowed size, and let the allocation path
1194 // figure out the safe size for current allocation.
1195 return ShenandoahHeapRegion::max_tlab_size_bytes();
1196 } else {
1197 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1198 }
1199 }
1200
1201 size_t ShenandoahHeap::max_tlab_size() const {
1202 // Returns size in words
1203 return ShenandoahHeapRegion::max_tlab_size_words();
1204 }
1205
1206 void ShenandoahHeap::collect(GCCause::Cause cause) {
1207 control_thread()->request_gc(cause);
1208 }
1209
1210 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1211 //assert(false, "Shouldn't need to do full collections");
1212 }
1213
1214 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1215 ShenandoahHeapRegion* r = heap_region_containing(addr);
1216 if (r != nullptr) {
1217 return r->block_start(addr);
1218 }
1219 return nullptr;
1220 }
1221
1222 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1223 ShenandoahHeapRegion* r = heap_region_containing(addr);
1224 return r->block_is_obj(addr);
1225 }
1226
1227 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1228 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1229 }
1230
1231 void ShenandoahHeap::prepare_for_verify() {
1232 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1233 labs_make_parsable();
1234 }
1235 }
1236
1237 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1238 tcl->do_thread(_control_thread);
1239 workers()->threads_do(tcl);
1240 if (_safepoint_workers != nullptr) {
1241 _safepoint_workers->threads_do(tcl);
1242 }
1243 }
1244
1245 void ShenandoahHeap::print_tracing_info() const {
1246 LogTarget(Info, gc, stats) lt;
1247 if (lt.is_enabled()) {
1248 ResourceMark rm;
1249 LogStream ls(lt);
1250
1251 phase_timings()->print_global_on(&ls);
1252
1253 ls.cr();
1254 ls.cr();
1255
1256 shenandoah_policy()->print_gc_stats(&ls);
1257
1258 ls.cr();
1259 ls.cr();
1260 }
1261 }
1262
1263 void ShenandoahHeap::verify(VerifyOption vo) {
1264 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1265 if (ShenandoahVerify) {
1266 verifier()->verify_generic(vo);
1267 } else {
1268 // TODO: Consider allocating verification bitmaps on demand,
1269 // and turn this on unconditionally.
1270 }
1271 }
1272 }
1273 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1274 return _free_set->capacity();
1275 }
1276
1277 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1278 private:
1279 MarkBitMap* _bitmap;
1280 ShenandoahScanObjectStack* _oop_stack;
1281 ShenandoahHeap* const _heap;
1282 ShenandoahMarkingContext* const _marking_context;
1283
1284 template <class T>
1285 void do_oop_work(T* p) {
1286 T o = RawAccess<>::oop_load(p);
1287 if (!CompressedOops::is_null(o)) {
1288 oop obj = CompressedOops::decode_not_null(o);
1289 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1290 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1291 return;
1292 }
1293 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1294
1295 assert(oopDesc::is_oop(obj), "must be a valid oop");
1296 if (!_bitmap->is_marked(obj)) {
1297 _bitmap->mark(obj);
1298 _oop_stack->push(obj);
1299 }
1300 }
1301 }
1302 public:
1303 ObjectIterateScanRootClosure(MarkBitMap* bitmap, ShenandoahScanObjectStack* oop_stack) :
1304 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1305 _marking_context(_heap->marking_context()) {}
1306 void do_oop(oop* p) { do_oop_work(p); }
1307 void do_oop(narrowOop* p) { do_oop_work(p); }
1308 };
1309
1310 /*
1311 * This is public API, used in preparation of object_iterate().
1312 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1313 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1314 * control, we call SH::tlabs_retire, SH::gclabs_retire.
1315 */
1316 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1317 // No-op.
1318 }
1319
1320 /*
1321 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1322 *
1323 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1324 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1325 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1326 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1327 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1328 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1329 * wiped the bitmap in preparation for next marking).
1330 *
1331 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1332 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1333 * is allowed to report dead objects, but is not required to do so.
1334 */
1335 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1336 // Reset bitmap
1337 if (!prepare_aux_bitmap_for_iteration())
1338 return;
1339
1340 ShenandoahScanObjectStack oop_stack;
1341 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1342 // Seed the stack with root scan
1343 scan_roots_for_iteration(&oop_stack, &oops);
1344
1345 // Work through the oop stack to traverse heap
1346 while (! oop_stack.is_empty()) {
1347 oop obj = oop_stack.pop();
1348 assert(oopDesc::is_oop(obj), "must be a valid oop");
1349 cl->do_object(obj);
1350 obj->oop_iterate(&oops);
1351 }
1352
1353 assert(oop_stack.is_empty(), "should be empty");
1354 // Reclaim bitmap
1355 reclaim_aux_bitmap_for_iteration();
1356 }
1357
1358 bool ShenandoahHeap::prepare_aux_bitmap_for_iteration() {
1359 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1360
1361 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1362 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1363 return false;
1364 }
1365 // Reset bitmap
1366 _aux_bit_map.clear();
1367 return true;
1368 }
1369
1370 void ShenandoahHeap::scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops) {
1371 // Process GC roots according to current GC cycle
1372 // This populates the work stack with initial objects
1373 // It is important to relinquish the associated locks before diving
1374 // into heap dumper
1375 uint n_workers = safepoint_workers() != nullptr ? safepoint_workers()->active_workers() : 1;
1376 ShenandoahHeapIterationRootScanner rp(n_workers);
1377 rp.roots_do(oops);
1378 }
1379
1380 void ShenandoahHeap::reclaim_aux_bitmap_for_iteration() {
1381 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1382 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1383 }
1384 }
1385
1386 // Closure for parallelly iterate objects
1387 class ShenandoahObjectIterateParScanClosure : public BasicOopIterateClosure {
1388 private:
1389 MarkBitMap* _bitmap;
1390 ShenandoahObjToScanQueue* _queue;
1391 ShenandoahHeap* const _heap;
1392 ShenandoahMarkingContext* const _marking_context;
1393
1394 template <class T>
1395 void do_oop_work(T* p) {
1396 T o = RawAccess<>::oop_load(p);
1397 if (!CompressedOops::is_null(o)) {
1398 oop obj = CompressedOops::decode_not_null(o);
1399 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1400 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1401 return;
1402 }
1403 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1404
1405 assert(oopDesc::is_oop(obj), "Must be a valid oop");
1406 if (_bitmap->par_mark(obj)) {
1407 _queue->push(ShenandoahMarkTask(obj));
1408 }
1409 }
1410 }
1411 public:
1412 ShenandoahObjectIterateParScanClosure(MarkBitMap* bitmap, ShenandoahObjToScanQueue* q) :
1413 _bitmap(bitmap), _queue(q), _heap(ShenandoahHeap::heap()),
1414 _marking_context(_heap->marking_context()) {}
1415 void do_oop(oop* p) { do_oop_work(p); }
1416 void do_oop(narrowOop* p) { do_oop_work(p); }
1417 };
1418
1419 // Object iterator for parallel heap iteraion.
1420 // The root scanning phase happenes in construction as a preparation of
1421 // parallel marking queues.
1422 // Every worker processes it's own marking queue. work-stealing is used
1423 // to balance workload.
1424 class ShenandoahParallelObjectIterator : public ParallelObjectIteratorImpl {
1425 private:
1426 uint _num_workers;
1427 bool _init_ready;
1428 MarkBitMap* _aux_bit_map;
1429 ShenandoahHeap* _heap;
1430 ShenandoahScanObjectStack _roots_stack; // global roots stack
1431 ShenandoahObjToScanQueueSet* _task_queues;
1432 public:
1433 ShenandoahParallelObjectIterator(uint num_workers, MarkBitMap* bitmap) :
1434 _num_workers(num_workers),
1435 _init_ready(false),
1436 _aux_bit_map(bitmap),
1437 _heap(ShenandoahHeap::heap()) {
1438 // Initialize bitmap
1439 _init_ready = _heap->prepare_aux_bitmap_for_iteration();
1440 if (!_init_ready) {
1441 return;
1442 }
1443
1444 ObjectIterateScanRootClosure oops(_aux_bit_map, &_roots_stack);
1445 _heap->scan_roots_for_iteration(&_roots_stack, &oops);
1446
1447 _init_ready = prepare_worker_queues();
1448 }
1449
1450 ~ShenandoahParallelObjectIterator() {
1451 // Reclaim bitmap
1452 _heap->reclaim_aux_bitmap_for_iteration();
1453 // Reclaim queue for workers
1454 if (_task_queues!= nullptr) {
1455 for (uint i = 0; i < _num_workers; ++i) {
1456 ShenandoahObjToScanQueue* q = _task_queues->queue(i);
1457 if (q != nullptr) {
1458 delete q;
1459 _task_queues->register_queue(i, nullptr);
1460 }
1461 }
1462 delete _task_queues;
1463 _task_queues = nullptr;
1464 }
1465 }
1466
1467 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
1468 if (_init_ready) {
1469 object_iterate_parallel(cl, worker_id, _task_queues);
1470 }
1471 }
1472
1473 private:
1474 // Divide global root_stack into worker queues
1475 bool prepare_worker_queues() {
1476 _task_queues = new ShenandoahObjToScanQueueSet((int) _num_workers);
1477 // Initialize queues for every workers
1478 for (uint i = 0; i < _num_workers; ++i) {
1479 ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue();
1480 _task_queues->register_queue(i, task_queue);
1481 }
1482 // Divide roots among the workers. Assume that object referencing distribution
1483 // is related with root kind, use round-robin to make every worker have same chance
1484 // to process every kind of roots
1485 size_t roots_num = _roots_stack.size();
1486 if (roots_num == 0) {
1487 // No work to do
1488 return false;
1489 }
1490
1491 for (uint j = 0; j < roots_num; j++) {
1492 uint stack_id = j % _num_workers;
1493 oop obj = _roots_stack.pop();
1494 _task_queues->queue(stack_id)->push(ShenandoahMarkTask(obj));
1495 }
1496 return true;
1497 }
1498
1499 void object_iterate_parallel(ObjectClosure* cl,
1500 uint worker_id,
1501 ShenandoahObjToScanQueueSet* queue_set) {
1502 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1503 assert(queue_set != nullptr, "task queue must not be null");
1504
1505 ShenandoahObjToScanQueue* q = queue_set->queue(worker_id);
1506 assert(q != nullptr, "object iterate queue must not be null");
1507
1508 ShenandoahMarkTask t;
1509 ShenandoahObjectIterateParScanClosure oops(_aux_bit_map, q);
1510
1511 // Work through the queue to traverse heap.
1512 // Steal when there is no task in queue.
1513 while (q->pop(t) || queue_set->steal(worker_id, t)) {
1514 oop obj = t.obj();
1515 assert(oopDesc::is_oop(obj), "must be a valid oop");
1516 cl->do_object(obj);
1517 obj->oop_iterate(&oops);
1518 }
1519 assert(q->is_empty(), "should be empty");
1520 }
1521 };
1522
1523 ParallelObjectIteratorImpl* ShenandoahHeap::parallel_object_iterator(uint workers) {
1524 return new ShenandoahParallelObjectIterator(workers, &_aux_bit_map);
1525 }
1526
1527 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1528 void ShenandoahHeap::keep_alive(oop obj) {
1529 if (is_concurrent_mark_in_progress() && (obj != nullptr)) {
1530 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1531 }
1532 }
1533
1534 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1535 for (size_t i = 0; i < num_regions(); i++) {
1536 ShenandoahHeapRegion* current = get_region(i);
1537 blk->heap_region_do(current);
1538 }
1539 }
1540
1541 class ShenandoahParallelHeapRegionTask : public WorkerTask {
1542 private:
1543 ShenandoahHeap* const _heap;
1544 ShenandoahHeapRegionClosure* const _blk;
1545
1546 shenandoah_padding(0);
1547 volatile size_t _index;
1548 shenandoah_padding(1);
1549
1550 public:
1551 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1552 WorkerTask("Shenandoah Parallel Region Operation"),
1553 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1554
1555 void work(uint worker_id) {
1556 ShenandoahParallelWorkerSession worker_session(worker_id);
1557 size_t stride = ShenandoahParallelRegionStride;
1558
1559 size_t max = _heap->num_regions();
1560 while (Atomic::load(&_index) < max) {
1561 size_t cur = Atomic::fetch_then_add(&_index, stride, memory_order_relaxed);
1562 size_t start = cur;
1563 size_t end = MIN2(cur + stride, max);
1564 if (start >= max) break;
1565
1566 for (size_t i = cur; i < end; i++) {
1567 ShenandoahHeapRegion* current = _heap->get_region(i);
1568 _blk->heap_region_do(current);
1569 }
1570 }
1571 }
1572 };
1573
1574 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1575 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1576 if (num_regions() > ShenandoahParallelRegionStride) {
1577 ShenandoahParallelHeapRegionTask task(blk);
1578 workers()->run_task(&task);
1579 } else {
1580 heap_region_iterate(blk);
1581 }
1582 }
1583
1584 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1585 private:
1586 ShenandoahMarkingContext* const _ctx;
1587 public:
1588 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1589
1590 void heap_region_do(ShenandoahHeapRegion* r) {
1591 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1592 if (r->is_active()) {
1593 // Check if region needs updating its TAMS. We have updated it already during concurrent
1594 // reset, so it is very likely we don't need to do another write here.
1595 if (_ctx->top_at_mark_start(r) != r->top()) {
1596 _ctx->capture_top_at_mark_start(r);
1597 }
1598 } else {
1599 assert(_ctx->top_at_mark_start(r) == r->top(),
1600 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1601 }
1602 }
1603
1604 bool is_thread_safe() { return true; }
1605 };
1606
1607 class ShenandoahRendezvousClosure : public HandshakeClosure {
1608 public:
1609 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
1610 inline void do_thread(Thread* thread) {}
1611 };
1612
1613 void ShenandoahHeap::rendezvous_threads() {
1614 ShenandoahRendezvousClosure cl;
1615 Handshake::execute(&cl);
1616 }
1617
1618 void ShenandoahHeap::recycle_trash() {
1619 free_set()->recycle_trash();
1620 }
1621
1622 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1623 private:
1624 ShenandoahMarkingContext* const _ctx;
1625 public:
1626 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1627
1628 void heap_region_do(ShenandoahHeapRegion* r) {
1629 if (r->is_active()) {
1630 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1631 // anyway to capture any updates that happened since now.
1632 r->clear_live_data();
1633 _ctx->capture_top_at_mark_start(r);
1634 }
1635 }
1636
1637 bool is_thread_safe() { return true; }
1638 };
1639
1640 void ShenandoahHeap::prepare_gc() {
1641 reset_mark_bitmap();
1642
1643 ShenandoahResetUpdateRegionStateClosure cl;
1644 parallel_heap_region_iterate(&cl);
1645 }
1646
1647 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1648 private:
1649 ShenandoahMarkingContext* const _ctx;
1650 ShenandoahHeapLock* const _lock;
1651
1652 public:
1653 ShenandoahFinalMarkUpdateRegionStateClosure() :
1654 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1655
1656 void heap_region_do(ShenandoahHeapRegion* r) {
1657 if (r->is_active()) {
1658 // All allocations past TAMS are implicitly live, adjust the region data.
1659 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1660 HeapWord *tams = _ctx->top_at_mark_start(r);
1661 HeapWord *top = r->top();
1662 if (top > tams) {
1663 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1664 }
1665
1666 // We are about to select the collection set, make sure it knows about
1667 // current pinning status. Also, this allows trashing more regions that
1668 // now have their pinning status dropped.
1669 if (r->is_pinned()) {
1670 if (r->pin_count() == 0) {
1671 ShenandoahHeapLocker locker(_lock);
1672 r->make_unpinned();
1673 }
1674 } else {
1675 if (r->pin_count() > 0) {
1676 ShenandoahHeapLocker locker(_lock);
1677 r->make_pinned();
1678 }
1679 }
1680
1681 // Remember limit for updating refs. It's guaranteed that we get no
1682 // from-space-refs written from here on.
1683 r->set_update_watermark_at_safepoint(r->top());
1684 } else {
1685 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1686 assert(_ctx->top_at_mark_start(r) == r->top(),
1687 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1688 }
1689 }
1690
1691 bool is_thread_safe() { return true; }
1692 };
1693
1694 void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) {
1695 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
1696 {
1697 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states :
1698 ShenandoahPhaseTimings::degen_gc_final_update_region_states);
1699 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1700 parallel_heap_region_iterate(&cl);
1701
1702 assert_pinned_region_status();
1703 }
1704
1705 {
1706 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset :
1707 ShenandoahPhaseTimings::degen_gc_choose_cset);
1708 ShenandoahHeapLocker locker(lock());
1709 _collection_set->clear();
1710 heuristics()->choose_collection_set(_collection_set);
1711 }
1712
1713 {
1714 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset :
1715 ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset);
1716 ShenandoahHeapLocker locker(lock());
1717 _free_set->rebuild();
1718 }
1719 }
1720
1721 void ShenandoahHeap::do_class_unloading() {
1722 _unloader.unload();
1723 }
1724
1725 void ShenandoahHeap::stw_weak_refs(bool full_gc) {
1726 // Weak refs processing
1727 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
1728 : ShenandoahPhaseTimings::degen_gc_weakrefs;
1729 ShenandoahTimingsTracker t(phase);
1730 ShenandoahGCWorkerPhase worker_phase(phase);
1731 ref_processor()->process_references(phase, workers(), false /* concurrent */);
1732 }
1733
1734 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
1735 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1736
1737 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
1738 // make them parsable for update code to work correctly. Plus, we can compute new sizes
1739 // for future GCLABs here.
1740 if (UseTLAB) {
1741 ShenandoahGCPhase phase(concurrent ?
1742 ShenandoahPhaseTimings::init_update_refs_manage_gclabs :
1743 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs);
1744 gclabs_retire(ResizeTLAB);
1745 }
1746
1747 _update_refs_iterator.reset();
1748 }
1749
1750 void ShenandoahHeap::set_gc_state_all_threads(char state) {
1751 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1752 ShenandoahThreadLocalData::set_gc_state(t, state);
1753 }
1754 }
1755
1756 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1757 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1758 _gc_state.set_cond(mask, value);
1759 set_gc_state_all_threads(_gc_state.raw_value());
1760 }
1761
1762 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1763 assert(!has_forwarded_objects(), "Not expected before/after mark phase");
1764 set_gc_state_mask(MARKING, in_progress);
1765 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1766 }
1767
1768 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1769 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1770 set_gc_state_mask(EVACUATION, in_progress);
1771 }
1772
1773 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
1774 if (in_progress) {
1775 _concurrent_strong_root_in_progress.set();
1776 } else {
1777 _concurrent_strong_root_in_progress.unset();
1778 }
1779 }
1780
1781 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) {
1782 set_gc_state_mask(WEAK_ROOTS, cond);
1783 }
1784
1785 GCTracer* ShenandoahHeap::tracer() {
1786 return shenandoah_policy()->tracer();
1787 }
1788
1789 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1790 return _free_set->used();
1791 }
1792
1793 bool ShenandoahHeap::try_cancel_gc() {
1794 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1795 return prev == CANCELLABLE;
1796 }
1797
1798 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1799 if (try_cancel_gc()) {
1800 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1801 log_info(gc)("%s", msg.buffer());
1802 Events::log(Thread::current(), "%s", msg.buffer());
1803 }
1804 }
1805
1806 uint ShenandoahHeap::max_workers() {
1807 return _max_workers;
1808 }
1809
1810 void ShenandoahHeap::stop() {
1811 // The shutdown sequence should be able to terminate when GC is running.
1812
1813 // Step 0. Notify policy to disable event recording.
1814 _shenandoah_policy->record_shutdown();
1815
1816 // Step 1. Notify control thread that we are in shutdown.
1817 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1818 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1819 control_thread()->prepare_for_graceful_shutdown();
1820
1821 // Step 2. Notify GC workers that we are cancelling GC.
1822 cancel_gc(GCCause::_shenandoah_stop_vm);
1823
1824 // Step 3. Wait until GC worker exits normally.
1825 control_thread()->stop();
1826 }
1827
1828 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
1829 if (!unload_classes()) return;
1830 // Unload classes and purge SystemDictionary.
1831 {
1832 ShenandoahPhaseTimings::Phase phase = full_gc ?
1833 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1834 ShenandoahPhaseTimings::degen_gc_purge_class_unload;
1835 ShenandoahIsAliveSelector is_alive;
1836 {
1837 CodeCache::UnlinkingScope scope(is_alive.is_alive_closure());
1838 ShenandoahGCPhase gc_phase(phase);
1839 ShenandoahGCWorkerPhase worker_phase(phase);
1840 bool unloading_occurred = SystemDictionary::do_unloading(gc_timer());
1841
1842 uint num_workers = _workers->active_workers();
1843 ShenandoahClassUnloadingTask unlink_task(phase, num_workers, unloading_occurred);
1844 _workers->run_task(&unlink_task);
1845 }
1846 // Release unloaded nmethods's memory.
1847 CodeCache::flush_unlinked_nmethods();
1848 }
1849
1850 {
1851 ShenandoahGCPhase phase(full_gc ?
1852 ShenandoahPhaseTimings::full_gc_purge_cldg :
1853 ShenandoahPhaseTimings::degen_gc_purge_cldg);
1854 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
1855 }
1856 // Resize and verify metaspace
1857 MetaspaceGC::compute_new_size();
1858 DEBUG_ONLY(MetaspaceUtils::verify();)
1859 }
1860
1861 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
1862 // so they should not have forwarded oops.
1863 // However, we do need to "null" dead oops in the roots, if can not be done
1864 // in concurrent cycles.
1865 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
1866 uint num_workers = _workers->active_workers();
1867 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
1868 ShenandoahPhaseTimings::full_gc_purge_weak_par :
1869 ShenandoahPhaseTimings::degen_gc_purge_weak_par;
1870 ShenandoahGCPhase phase(timing_phase);
1871 ShenandoahGCWorkerPhase worker_phase(timing_phase);
1872 // Cleanup weak roots
1873 if (has_forwarded_objects()) {
1874 ShenandoahForwardedIsAliveClosure is_alive;
1875 ShenandoahUpdateRefsClosure keep_alive;
1876 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
1877 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers);
1878 _workers->run_task(&cleaning_task);
1879 } else {
1880 ShenandoahIsAliveClosure is_alive;
1881 #ifdef ASSERT
1882 ShenandoahAssertNotForwardedClosure verify_cl;
1883 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
1884 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers);
1885 #else
1886 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
1887 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers);
1888 #endif
1889 _workers->run_task(&cleaning_task);
1890 }
1891 }
1892
1893 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
1894 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1895 assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC");
1896 ShenandoahGCPhase phase(full_gc ?
1897 ShenandoahPhaseTimings::full_gc_purge :
1898 ShenandoahPhaseTimings::degen_gc_purge);
1899 stw_weak_refs(full_gc);
1900 stw_process_weak_roots(full_gc);
1901 stw_unload_classes(full_gc);
1902 }
1903
1904 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
1905 set_gc_state_mask(HAS_FORWARDED, cond);
1906 }
1907
1908 void ShenandoahHeap::set_unload_classes(bool uc) {
1909 _unload_classes.set_cond(uc);
1910 }
1911
1912 bool ShenandoahHeap::unload_classes() const {
1913 return _unload_classes.is_set();
1914 }
1915
1916 address ShenandoahHeap::in_cset_fast_test_addr() {
1917 ShenandoahHeap* heap = ShenandoahHeap::heap();
1918 assert(heap->collection_set() != nullptr, "Sanity");
1919 return (address) heap->collection_set()->biased_map_address();
1920 }
1921
1922 size_t ShenandoahHeap::bytes_allocated_since_gc_start() const {
1923 return Atomic::load(&_bytes_allocated_since_gc_start);
1924 }
1925
1926 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
1927 Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0);
1928 }
1929
1930 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
1931 _degenerated_gc_in_progress.set_cond(in_progress);
1932 }
1933
1934 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
1935 _full_gc_in_progress.set_cond(in_progress);
1936 }
1937
1938 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
1939 assert (is_full_gc_in_progress(), "should be");
1940 _full_gc_move_in_progress.set_cond(in_progress);
1941 }
1942
1943 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
1944 set_gc_state_mask(UPDATEREFS, in_progress);
1945 }
1946
1947 void ShenandoahHeap::register_nmethod(nmethod* nm) {
1948 ShenandoahCodeRoots::register_nmethod(nm);
1949 }
1950
1951 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
1952 ShenandoahCodeRoots::unregister_nmethod(nm);
1953 }
1954
1955 void ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
1956 heap_region_containing(o)->record_pin();
1957 }
1958
1959 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
1960 ShenandoahHeapRegion* r = heap_region_containing(o);
1961 assert(r != nullptr, "Sanity");
1962 assert(r->pin_count() > 0, "Region " SIZE_FORMAT " should have non-zero pins", r->index());
1963 r->record_unpin();
1964 }
1965
1966 void ShenandoahHeap::sync_pinned_region_status() {
1967 ShenandoahHeapLocker locker(lock());
1968
1969 for (size_t i = 0; i < num_regions(); i++) {
1970 ShenandoahHeapRegion *r = get_region(i);
1971 if (r->is_active()) {
1972 if (r->is_pinned()) {
1973 if (r->pin_count() == 0) {
1974 r->make_unpinned();
1975 }
1976 } else {
1977 if (r->pin_count() > 0) {
1978 r->make_pinned();
1979 }
1980 }
1981 }
1982 }
1983
1984 assert_pinned_region_status();
1985 }
1986
1987 #ifdef ASSERT
1988 void ShenandoahHeap::assert_pinned_region_status() {
1989 for (size_t i = 0; i < num_regions(); i++) {
1990 ShenandoahHeapRegion* r = get_region(i);
1991 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
1992 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
1993 }
1994 }
1995 #endif
1996
1997 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
1998 return _gc_timer;
1999 }
2000
2001 void ShenandoahHeap::prepare_concurrent_roots() {
2002 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2003 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
2004 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
2005 set_concurrent_weak_root_in_progress(true);
2006 if (unload_classes()) {
2007 _unloader.prepare();
2008 }
2009 }
2010
2011 void ShenandoahHeap::finish_concurrent_roots() {
2012 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2013 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
2014 if (unload_classes()) {
2015 _unloader.finish();
2016 }
2017 }
2018
2019 #ifdef ASSERT
2020 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2021 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2022
2023 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2024 if (UseDynamicNumberOfGCThreads) {
2025 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2026 } else {
2027 // Use ParallelGCThreads inside safepoints
2028 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
2029 }
2030 } else {
2031 if (UseDynamicNumberOfGCThreads) {
2032 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2033 } else {
2034 // Use ConcGCThreads outside safepoints
2035 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2036 }
2037 }
2038 }
2039 #endif
2040
2041 ShenandoahVerifier* ShenandoahHeap::verifier() {
2042 guarantee(ShenandoahVerify, "Should be enabled");
2043 assert (_verifier != nullptr, "sanity");
2044 return _verifier;
2045 }
2046
2047 template<bool CONCURRENT>
2048 class ShenandoahUpdateHeapRefsTask : public WorkerTask {
2049 private:
2050 ShenandoahHeap* _heap;
2051 ShenandoahRegionIterator* _regions;
2052 public:
2053 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
2054 WorkerTask("Shenandoah Update References"),
2055 _heap(ShenandoahHeap::heap()),
2056 _regions(regions) {
2057 }
2058
2059 void work(uint worker_id) {
2060 if (CONCURRENT) {
2061 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2062 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2063 do_work<ShenandoahConcUpdateRefsClosure>();
2064 } else {
2065 ShenandoahParallelWorkerSession worker_session(worker_id);
2066 do_work<ShenandoahSTWUpdateRefsClosure>();
2067 }
2068 }
2069
2070 private:
2071 template<class T>
2072 void do_work() {
2073 T cl;
2074 ShenandoahHeapRegion* r = _regions->next();
2075 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2076 while (r != nullptr) {
2077 HeapWord* update_watermark = r->get_update_watermark();
2078 assert (update_watermark >= r->bottom(), "sanity");
2079 if (r->is_active() && !r->is_cset()) {
2080 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2081 }
2082 if (ShenandoahPacing) {
2083 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2084 }
2085 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2086 return;
2087 }
2088 r = _regions->next();
2089 }
2090 }
2091 };
2092
2093 void ShenandoahHeap::update_heap_references(bool concurrent) {
2094 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2095
2096 if (concurrent) {
2097 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator);
2098 workers()->run_task(&task);
2099 } else {
2100 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
2101 workers()->run_task(&task);
2102 }
2103 }
2104
2105
2106 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2107 private:
2108 ShenandoahHeapLock* const _lock;
2109
2110 public:
2111 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2112
2113 void heap_region_do(ShenandoahHeapRegion* r) {
2114 // Drop unnecessary "pinned" state from regions that does not have CP marks
2115 // anymore, as this would allow trashing them.
2116
2117 if (r->is_active()) {
2118 if (r->is_pinned()) {
2119 if (r->pin_count() == 0) {
2120 ShenandoahHeapLocker locker(_lock);
2121 r->make_unpinned();
2122 }
2123 } else {
2124 if (r->pin_count() > 0) {
2125 ShenandoahHeapLocker locker(_lock);
2126 r->make_pinned();
2127 }
2128 }
2129 }
2130 }
2131
2132 bool is_thread_safe() { return true; }
2133 };
2134
2135 void ShenandoahHeap::update_heap_region_states(bool concurrent) {
2136 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2137 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2138
2139 {
2140 ShenandoahGCPhase phase(concurrent ?
2141 ShenandoahPhaseTimings::final_update_refs_update_region_states :
2142 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states);
2143 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2144 parallel_heap_region_iterate(&cl);
2145
2146 assert_pinned_region_status();
2147 }
2148
2149 {
2150 ShenandoahGCPhase phase(concurrent ?
2151 ShenandoahPhaseTimings::final_update_refs_trash_cset :
2152 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset);
2153 trash_cset_regions();
2154 }
2155 }
2156
2157 void ShenandoahHeap::rebuild_free_set(bool concurrent) {
2158 {
2159 ShenandoahGCPhase phase(concurrent ?
2160 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
2161 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
2162 ShenandoahHeapLocker locker(lock());
2163 _free_set->rebuild();
2164 }
2165 }
2166
2167 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2168 print_on(st);
2169 st->cr();
2170 print_heap_regions_on(st);
2171 }
2172
2173 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2174 size_t slice = r->index() / _bitmap_regions_per_slice;
2175
2176 size_t regions_from = _bitmap_regions_per_slice * slice;
2177 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2178 for (size_t g = regions_from; g < regions_to; g++) {
2179 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2180 if (skip_self && g == r->index()) continue;
2181 if (get_region(g)->is_committed()) {
2182 return true;
2183 }
2184 }
2185 return false;
2186 }
2187
2188 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2189 shenandoah_assert_heaplocked();
2190
2191 // Bitmaps in special regions do not need commits
2192 if (_bitmap_region_special) {
2193 return true;
2194 }
2195
2196 if (is_bitmap_slice_committed(r, true)) {
2197 // Some other region from the group is already committed, meaning the bitmap
2198 // slice is already committed, we exit right away.
2199 return true;
2200 }
2201
2202 // Commit the bitmap slice:
2203 size_t slice = r->index() / _bitmap_regions_per_slice;
2204 size_t off = _bitmap_bytes_per_slice * slice;
2205 size_t len = _bitmap_bytes_per_slice;
2206 char* start = (char*) _bitmap_region.start() + off;
2207
2208 if (!os::commit_memory(start, len, false)) {
2209 return false;
2210 }
2211
2212 if (AlwaysPreTouch) {
2213 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size);
2214 }
2215
2216 return true;
2217 }
2218
2219 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2220 shenandoah_assert_heaplocked();
2221
2222 // Bitmaps in special regions do not need uncommits
2223 if (_bitmap_region_special) {
2224 return true;
2225 }
2226
2227 if (is_bitmap_slice_committed(r, true)) {
2228 // Some other region from the group is still committed, meaning the bitmap
2229 // slice is should stay committed, exit right away.
2230 return true;
2231 }
2232
2233 // Uncommit the bitmap slice:
2234 size_t slice = r->index() / _bitmap_regions_per_slice;
2235 size_t off = _bitmap_bytes_per_slice * slice;
2236 size_t len = _bitmap_bytes_per_slice;
2237 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2238 return false;
2239 }
2240 return true;
2241 }
2242
2243 void ShenandoahHeap::safepoint_synchronize_begin() {
2244 if (ShenandoahSuspendibleWorkers) {
2245 SuspendibleThreadSet::synchronize();
2246 }
2247 }
2248
2249 void ShenandoahHeap::safepoint_synchronize_end() {
2250 if (ShenandoahSuspendibleWorkers) {
2251 SuspendibleThreadSet::desynchronize();
2252 }
2253 }
2254
2255 void ShenandoahHeap::entry_uncommit(double shrink_before, size_t shrink_until) {
2256 static const char *msg = "Concurrent uncommit";
2257 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
2258 EventMark em("%s", msg);
2259
2260 op_uncommit(shrink_before, shrink_until);
2261 }
2262
2263 void ShenandoahHeap::try_inject_alloc_failure() {
2264 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2265 _inject_alloc_failure.set();
2266 os::naked_short_sleep(1);
2267 if (cancelled_gc()) {
2268 log_info(gc)("Allocation failure was successfully injected");
2269 }
2270 }
2271 }
2272
2273 bool ShenandoahHeap::should_inject_alloc_failure() {
2274 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2275 }
2276
2277 void ShenandoahHeap::initialize_serviceability() {
2278 _memory_pool = new ShenandoahMemoryPool(this);
2279 _cycle_memory_manager.add_pool(_memory_pool);
2280 _stw_memory_manager.add_pool(_memory_pool);
2281 }
2282
2283 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2284 GrowableArray<GCMemoryManager*> memory_managers(2);
2285 memory_managers.append(&_cycle_memory_manager);
2286 memory_managers.append(&_stw_memory_manager);
2287 return memory_managers;
2288 }
2289
2290 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2291 GrowableArray<MemoryPool*> memory_pools(1);
2292 memory_pools.append(_memory_pool);
2293 return memory_pools;
2294 }
2295
2296 MemoryUsage ShenandoahHeap::memory_usage() {
2297 return _memory_pool->get_memory_usage();
2298 }
2299
2300 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2301 _heap(ShenandoahHeap::heap()),
2302 _index(0) {}
2303
2304 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2305 _heap(heap),
2306 _index(0) {}
2307
2308 void ShenandoahRegionIterator::reset() {
2309 _index = 0;
2310 }
2311
2312 bool ShenandoahRegionIterator::has_next() const {
2313 return _index < _heap->num_regions();
2314 }
2315
2316 char ShenandoahHeap::gc_state() const {
2317 return _gc_state.raw_value();
2318 }
2319
2320 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2321 #ifdef ASSERT
2322 assert(_liveness_cache != nullptr, "sanity");
2323 assert(worker_id < _max_workers, "sanity");
2324 for (uint i = 0; i < num_regions(); i++) {
2325 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2326 }
2327 #endif
2328 return _liveness_cache[worker_id];
2329 }
2330
2331 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2332 assert(worker_id < _max_workers, "sanity");
2333 assert(_liveness_cache != nullptr, "sanity");
2334 ShenandoahLiveData* ld = _liveness_cache[worker_id];
2335 for (uint i = 0; i < num_regions(); i++) {
2336 ShenandoahLiveData live = ld[i];
2337 if (live > 0) {
2338 ShenandoahHeapRegion* r = get_region(i);
2339 r->increase_live_data_gc_words(live);
2340 ld[i] = 0;
2341 }
2342 }
2343 }
2344
2345 bool ShenandoahHeap::requires_barriers(stackChunkOop obj) const {
2346 if (is_idle()) return false;
2347
2348 // Objects allocated after marking start are implicitly alive, don't need any barriers during
2349 // marking phase.
2350 if (is_concurrent_mark_in_progress() &&
2351 !marking_context()->allocated_after_mark_start(obj)) {
2352 return true;
2353 }
2354
2355 // Can not guarantee obj is deeply good.
2356 if (has_forwarded_objects()) {
2357 return true;
2358 }
2359
2360 return false;
2361 }