1 /*
2 * Copyright (c) 2023, 2024, 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/classUnloadingContext.hpp"
31 #include "gc/shared/gcArguments.hpp"
32 #include "gc/shared/gcTimer.hpp"
33 #include "gc/shared/gcTraceTime.inline.hpp"
34 #include "gc/shared/locationPrinter.inline.hpp"
35 #include "gc/shared/memAllocator.hpp"
36 #include "gc/shared/plab.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/stackWatermarkSet.hpp"
91 #include "runtime/vmThread.hpp"
92 #include "utilities/events.hpp"
93 #include "utilities/powerOfTwo.hpp"
94
95 class ShenandoahPretouchHeapTask : public WorkerTask {
96 private:
97 ShenandoahRegionIterator _regions;
98 const size_t _page_size;
99 public:
100 ShenandoahPretouchHeapTask(size_t page_size) :
101 WorkerTask("Shenandoah Pretouch Heap"),
102 _page_size(page_size) {}
103
104 virtual void work(uint worker_id) {
105 ShenandoahHeapRegion* r = _regions.next();
106 while (r != nullptr) {
107 if (r->is_committed()) {
108 os::pretouch_memory(r->bottom(), r->end(), _page_size);
109 }
110 r = _regions.next();
111 }
112 }
113 };
114
115 class ShenandoahPretouchBitmapTask : public WorkerTask {
116 private:
117 ShenandoahRegionIterator _regions;
118 char* _bitmap_base;
119 const size_t _bitmap_size;
120 const size_t _page_size;
121 public:
122 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
123 WorkerTask("Shenandoah Pretouch Bitmap"),
124 _bitmap_base(bitmap_base),
125 _bitmap_size(bitmap_size),
126 _page_size(page_size) {}
127
128 virtual void work(uint worker_id) {
129 ShenandoahHeapRegion* r = _regions.next();
130 while (r != nullptr) {
131 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
132 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
133 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
134
135 if (r->is_committed()) {
136 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
137 }
138
139 r = _regions.next();
140 }
141 }
142 };
143
144 jint ShenandoahHeap::initialize() {
145 //
146 // Figure out heap sizing
147 //
148
149 size_t init_byte_size = InitialHeapSize;
150 size_t min_byte_size = MinHeapSize;
151 size_t max_byte_size = MaxHeapSize;
152 size_t heap_alignment = HeapAlignment;
153
154 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
155
156 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
157 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
158
159 _num_regions = ShenandoahHeapRegion::region_count();
160 assert(_num_regions == (max_byte_size / reg_size_bytes),
161 "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT,
162 _num_regions, max_byte_size, reg_size_bytes);
163
164 // Now we know the number of regions, initialize the heuristics.
165 initialize_heuristics();
166
167 size_t num_committed_regions = init_byte_size / reg_size_bytes;
168 num_committed_regions = MIN2(num_committed_regions, _num_regions);
169 assert(num_committed_regions <= _num_regions, "sanity");
170 _initial_size = num_committed_regions * reg_size_bytes;
171
172 size_t num_min_regions = min_byte_size / reg_size_bytes;
173 num_min_regions = MIN2(num_min_regions, _num_regions);
174 assert(num_min_regions <= _num_regions, "sanity");
175 _minimum_size = num_min_regions * reg_size_bytes;
176
177 // Default to max heap size.
178 _soft_max_size = _num_regions * reg_size_bytes;
179
180 _committed = _initial_size;
181
182 size_t heap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
183 size_t bitmap_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
184 size_t region_page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
185
186 //
187 // Reserve and commit memory for heap
188 //
189
190 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
191 initialize_reserved_region(heap_rs);
192 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
193 _heap_region_special = heap_rs.special();
194
195 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
196 "Misaligned heap: " PTR_FORMAT, p2i(base()));
197 os::trace_page_sizes_for_requested_size("Heap",
198 max_byte_size, heap_alignment,
199 heap_rs.base(),
200 heap_rs.size(), heap_rs.page_size());
201
202 #if SHENANDOAH_OPTIMIZED_MARKTASK
203 // The optimized ShenandoahMarkTask takes some bits away from the full object bits.
204 // Fail if we ever attempt to address more than we can.
205 if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) {
206 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
207 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
208 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
209 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable());
210 vm_exit_during_initialization("Fatal Error", buf);
211 }
212 #endif
213
214 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
215 if (!_heap_region_special) {
216 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
217 "Cannot commit heap memory");
218 }
219
220 //
221 // Reserve and commit memory for bitmap(s)
222 //
223
224 size_t bitmap_size_orig = ShenandoahMarkBitMap::compute_size(heap_rs.size());
225 _bitmap_size = align_up(bitmap_size_orig, bitmap_page_size);
226
227 size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor();
228
229 guarantee(bitmap_bytes_per_region != 0,
230 "Bitmap bytes per region should not be zero");
231 guarantee(is_power_of_2(bitmap_bytes_per_region),
232 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
233
234 if (bitmap_page_size > bitmap_bytes_per_region) {
235 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
236 _bitmap_bytes_per_slice = bitmap_page_size;
237 } else {
238 _bitmap_regions_per_slice = 1;
239 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
240 }
241
242 guarantee(_bitmap_regions_per_slice >= 1,
243 "Should have at least one region per slice: " SIZE_FORMAT,
244 _bitmap_regions_per_slice);
245
246 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
247 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
248 _bitmap_bytes_per_slice, bitmap_page_size);
249
250 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
251 os::trace_page_sizes_for_requested_size("Mark Bitmap",
252 bitmap_size_orig, bitmap_page_size,
253 bitmap.base(),
254 bitmap.size(), bitmap.page_size());
255 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
256 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
257 _bitmap_region_special = bitmap.special();
258
259 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
260 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
261 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
262 if (!_bitmap_region_special) {
263 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
264 "Cannot commit bitmap memory");
265 }
266
267 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions, _max_workers);
268
269 if (ShenandoahVerify) {
270 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
271 os::trace_page_sizes_for_requested_size("Verify Bitmap",
272 bitmap_size_orig, bitmap_page_size,
273 verify_bitmap.base(),
274 verify_bitmap.size(), verify_bitmap.page_size());
275 if (!verify_bitmap.special()) {
276 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
277 "Cannot commit verification bitmap memory");
278 }
279 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
280 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
281 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
282 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
283 }
284
285 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
286 size_t aux_bitmap_page_size = bitmap_page_size;
287 #ifdef LINUX
288 // In THP "advise" mode, we refrain from advising the system to use large pages
289 // since we know these commits will be short lived, and there is no reason to trash
290 // the THP area with this bitmap.
291 if (UseTransparentHugePages) {
292 aux_bitmap_page_size = os::vm_page_size();
293 }
294 #endif
295 ReservedSpace aux_bitmap(_bitmap_size, aux_bitmap_page_size);
296 os::trace_page_sizes_for_requested_size("Aux Bitmap",
297 bitmap_size_orig, aux_bitmap_page_size,
298 aux_bitmap.base(),
299 aux_bitmap.size(), aux_bitmap.page_size());
300 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
301 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
302 _aux_bitmap_region_special = aux_bitmap.special();
303 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
304
305 //
306 // Create regions and region sets
307 //
308 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
309 size_t region_storage_size_orig = region_align * _num_regions;
310 size_t region_storage_size = align_up(region_storage_size_orig,
311 MAX2(region_page_size, os::vm_allocation_granularity()));
312
313 ReservedSpace region_storage(region_storage_size, region_page_size);
314 os::trace_page_sizes_for_requested_size("Region Storage",
315 region_storage_size_orig, region_page_size,
316 region_storage.base(),
317 region_storage.size(), region_storage.page_size());
318 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
319 if (!region_storage.special()) {
320 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
321 "Cannot commit region memory");
322 }
323
324 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks.
325 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there.
326 // If not successful, bite a bullet and allocate at whatever address.
327 {
328 const size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
329 const size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align);
330 const size_t cset_page_size = os::vm_page_size();
331
332 uintptr_t min = round_up_power_of_2(cset_align);
333 uintptr_t max = (1u << 30u);
334 ReservedSpace cset_rs;
335
336 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
337 char* req_addr = (char*)addr;
338 assert(is_aligned(req_addr, cset_align), "Should be aligned");
339 cset_rs = ReservedSpace(cset_size, cset_align, cset_page_size, req_addr);
340 if (cset_rs.is_reserved()) {
341 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr);
342 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
343 break;
344 }
345 }
346
347 if (_collection_set == nullptr) {
348 cset_rs = ReservedSpace(cset_size, cset_align, os::vm_page_size());
349 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
350 }
351 os::trace_page_sizes_for_requested_size("Collection Set",
352 cset_size, cset_page_size,
353 cset_rs.base(),
354 cset_rs.size(), cset_rs.page_size());
355 }
356
357 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
358 _free_set = new ShenandoahFreeSet(this, _num_regions);
359
360 {
361 ShenandoahHeapLocker locker(lock());
362
363 for (size_t i = 0; i < _num_regions; i++) {
364 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
365 bool is_committed = i < num_committed_regions;
366 void* loc = region_storage.base() + i * region_align;
367
368 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
369 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
370
371 _marking_context->initialize_top_at_mark_start(r);
372 _regions[i] = r;
373 assert(!collection_set()->is_in(i), "New region should not be in collection set");
374 }
375
376 // Initialize to complete
377 _marking_context->mark_complete();
378
379 _free_set->rebuild();
380 }
381
382 if (AlwaysPreTouch) {
383 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
384 // before initialize() below zeroes it with initializing thread. For any given region,
385 // we touch the region and the corresponding bitmaps from the same thread.
386 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
387
388 _pretouch_heap_page_size = heap_page_size;
389 _pretouch_bitmap_page_size = bitmap_page_size;
390
391 #ifdef LINUX
392 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
393 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
394 // them into huge one. Therefore, we need to pretouch with smaller pages.
395 if (UseTransparentHugePages) {
396 _pretouch_heap_page_size = (size_t)os::vm_page_size();
397 _pretouch_bitmap_page_size = (size_t)os::vm_page_size();
398 }
399 #endif
400
401 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
402 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
403
404 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size);
405 _workers->run_task(&bcl);
406
407 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size);
408 _workers->run_task(&hcl);
409 }
410
411 //
412 // Initialize the rest of GC subsystems
413 //
414
415 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
416 for (uint worker = 0; worker < _max_workers; worker++) {
417 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
418 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
419 }
420
421 // There should probably be Shenandoah-specific options for these,
422 // just as there are G1-specific options.
423 {
424 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
425 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
426 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
427 }
428
429 _monitoring_support = new ShenandoahMonitoringSupport(this);
430 _phase_timings = new ShenandoahPhaseTimings(max_workers());
431 ShenandoahCodeRoots::initialize();
432
433 if (ShenandoahPacing) {
434 _pacer = new ShenandoahPacer(this);
435 _pacer->setup_for_idle();
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_state_changed(false),
507 _gc_no_progress_count(0),
508 _control_thread(nullptr),
509 _shenandoah_policy(policy),
510 _gc_mode(nullptr),
511 _heuristics(nullptr),
512 _free_set(nullptr),
513 _pacer(nullptr),
514 _verifier(nullptr),
515 _phase_timings(nullptr),
516 _monitoring_support(nullptr),
517 _memory_pool(nullptr),
518 _stw_memory_manager("Shenandoah Pauses"),
519 _cycle_memory_manager("Shenandoah Cycles"),
520 _gc_timer(new ConcurrentGCTimer()),
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::maybe_uncommit(double shrink_before, size_t shrink_until) {
758 assert (ShenandoahUncommit, "should be enabled");
759
760 // Determine if there is work to do. This avoids taking heap lock if there is
761 // no work available, avoids spamming logs with superfluous logging messages,
762 // and minimises the amount of work while locks are taken.
763
764 if (committed() <= shrink_until) return;
765
766 bool has_work = false;
767 for (size_t i = 0; i < num_regions(); i++) {
768 ShenandoahHeapRegion* r = get_region(i);
769 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
770 has_work = true;
771 break;
772 }
773 }
774
775 if (has_work) {
776 static const char* msg = "Concurrent uncommit";
777 ShenandoahConcurrentPhase gcPhase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
778 EventMark em("%s", msg);
779
780 op_uncommit(shrink_before, shrink_until);
781 }
782 }
783
784 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
785 assert (ShenandoahUncommit, "should be enabled");
786
787 // Application allocates from the beginning of the heap, and GC allocates at
788 // the end of it. It is more efficient to uncommit from the end, so that applications
789 // could enjoy the near committed regions. GC allocations are much less frequent,
790 // and therefore can accept the committing costs.
791
792 size_t count = 0;
793 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
794 ShenandoahHeapRegion* r = get_region(i - 1);
795 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
796 ShenandoahHeapLocker locker(lock());
797 if (r->is_empty_committed()) {
798 if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
799 break;
800 }
801
802 r->make_uncommitted();
803 count++;
804 }
805 }
806 SpinPause(); // allow allocators to take the lock
807 }
808
809 if (count > 0) {
810 notify_heap_changed();
811 }
812 }
813
814 bool ShenandoahHeap::check_soft_max_changed() {
815 size_t new_soft_max = Atomic::load(&SoftMaxHeapSize);
816 size_t old_soft_max = soft_max_capacity();
817 if (new_soft_max != old_soft_max) {
818 new_soft_max = MAX2(min_capacity(), new_soft_max);
819 new_soft_max = MIN2(max_capacity(), new_soft_max);
820 if (new_soft_max != old_soft_max) {
821 log_info(gc)("Soft Max Heap Size: " SIZE_FORMAT "%s -> " SIZE_FORMAT "%s",
822 byte_size_in_proper_unit(old_soft_max), proper_unit_for_byte_size(old_soft_max),
823 byte_size_in_proper_unit(new_soft_max), proper_unit_for_byte_size(new_soft_max)
824 );
825 set_soft_max_capacity(new_soft_max);
826 return true;
827 }
828 }
829 return false;
830 }
831
832 void ShenandoahHeap::notify_heap_changed() {
833 // Update monitoring counters when we took a new region. This amortizes the
834 // update costs on slow path.
835 monitoring_support()->notify_heap_changed();
836
837 // This is called from allocation path, and thus should be fast.
838 _heap_changed.try_set();
839 }
840
841 void ShenandoahHeap::set_forced_counters_update(bool value) {
842 monitoring_support()->set_forced_counters_update(value);
843 }
844
845 void ShenandoahHeap::handle_force_counters_update() {
846 monitoring_support()->handle_force_counters_update();
847 }
848
849 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
850 // New object should fit the GCLAB size
851 size_t min_size = MAX2(size, PLAB::min_size());
852
853 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
854 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
855 new_size = MIN2(new_size, PLAB::max_size());
856 new_size = MAX2(new_size, PLAB::min_size());
857
858 // Record new heuristic value even if we take any shortcut. This captures
859 // the case when moderately-sized objects always take a shortcut. At some point,
860 // heuristics should catch up with them.
861 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
862
863 if (new_size < size) {
864 // New size still does not fit the object. Fall back to shared allocation.
865 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
866 return nullptr;
867 }
868
869 // Retire current GCLAB, and allocate a new one.
870 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
871 gclab->retire();
872
873 size_t actual_size = 0;
874 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
875 if (gclab_buf == nullptr) {
876 return nullptr;
877 }
878
879 assert (size <= actual_size, "allocation should fit");
880
881 // ...and clear or zap just allocated TLAB, if needed.
882 if (ZeroTLAB) {
883 Copy::zero_to_words(gclab_buf, actual_size);
884 } else if (ZapTLAB) {
885 // Skip mangling the space corresponding to the object header to
886 // ensure that the returned space is not considered parsable by
887 // any concurrent GC thread.
888 size_t hdr_size = oopDesc::header_size();
889 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
890 }
891 gclab->set_buf(gclab_buf, actual_size);
892 return gclab->allocate(size);
893 }
894
895 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
896 size_t requested_size,
897 size_t* actual_size) {
898 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
899 HeapWord* res = allocate_memory(req);
900 if (res != nullptr) {
901 *actual_size = req.actual_size();
902 } else {
903 *actual_size = 0;
904 }
905 return res;
906 }
907
908 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
909 size_t word_size,
910 size_t* actual_size) {
911 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
912 HeapWord* res = allocate_memory(req);
913 if (res != nullptr) {
914 *actual_size = req.actual_size();
915 } else {
916 *actual_size = 0;
917 }
918 return res;
919 }
920
921 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
922 intptr_t pacer_epoch = 0;
923 bool in_new_region = false;
924 HeapWord* result = nullptr;
925
926 if (req.is_mutator_alloc()) {
927 if (ShenandoahPacing) {
928 pacer()->pace_for_alloc(req.size());
929 pacer_epoch = pacer()->epoch();
930 }
931
932 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
933 result = allocate_memory_under_lock(req, in_new_region);
934 }
935
936 // Check that gc overhead is not exceeded.
937 //
938 // Shenandoah will grind along for quite a while allocating one
939 // object at a time using shared (non-tlab) allocations. This check
940 // is testing that the GC overhead limit has not been exceeded.
941 // This will notify the collector to start a cycle, but will raise
942 // an OOME to the mutator if the last Full GCs have not made progress.
943 if (result == nullptr && !req.is_lab_alloc() && get_gc_no_progress_count() > ShenandoahNoProgressThreshold) {
944 control_thread()->handle_alloc_failure(req, false);
945 return nullptr;
946 }
947
948 // Block until control thread reacted, then retry allocation.
949 //
950 // It might happen that one of the threads requesting allocation would unblock
951 // way later after GC happened, only to fail the second allocation, because
952 // other threads have already depleted the free storage. In this case, a better
953 // strategy is to try again, as long as GC makes progress (or until at least
954 // one full GC has completed).
955 size_t original_count = shenandoah_policy()->full_gc_count();
956 while (result == nullptr
957 && (get_gc_no_progress_count() == 0 || original_count == shenandoah_policy()->full_gc_count())) {
958 control_thread()->handle_alloc_failure(req, true);
959 result = allocate_memory_under_lock(req, in_new_region);
960 }
961
962 if (log_is_enabled(Debug, gc, alloc)) {
963 ResourceMark rm;
964 log_debug(gc, alloc)("Thread: %s, Result: " PTR_FORMAT ", Request: %s, Size: " SIZE_FORMAT ", Original: " SIZE_FORMAT ", Latest: " SIZE_FORMAT,
965 Thread::current()->name(), p2i(result), req.type_string(), req.size(), original_count, get_gc_no_progress_count());
966 }
967 } else {
968 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
969 result = allocate_memory_under_lock(req, in_new_region);
970 // Do not call handle_alloc_failure() here, because we cannot block.
971 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
972 }
973
974 if (in_new_region) {
975 notify_heap_changed();
976 }
977
978 if (result != nullptr) {
979 size_t requested = req.size();
980 size_t actual = req.actual_size();
981
982 assert (req.is_lab_alloc() || (requested == actual),
983 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
984 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
985
986 if (req.is_mutator_alloc()) {
987 notify_mutator_alloc_words(actual, false);
988
989 // If we requested more than we were granted, give the rest back to pacer.
990 // This only matters if we are in the same pacing epoch: do not try to unpace
991 // over the budget for the other phase.
992 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
993 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
994 }
995 } else {
996 increase_used(actual*HeapWordSize);
997 }
998 }
999
1000 return result;
1001 }
1002
1003 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
1004 // If we are dealing with mutator allocation, then we may need to block for safepoint.
1005 // We cannot block for safepoint for GC allocations, because there is a high chance
1006 // we are already running at safepoint or from stack watermark machinery, and we cannot
1007 // block again.
1008 ShenandoahHeapLocker locker(lock(), req.is_mutator_alloc());
1009 return _free_set->allocate(req, in_new_region);
1010 }
1011
1012 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
1013 bool* gc_overhead_limit_was_exceeded) {
1014 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
1015 return allocate_memory(req);
1016 }
1017
1018 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
1019 size_t size,
1020 Metaspace::MetadataType mdtype) {
1021 MetaWord* result;
1022
1023 // Inform metaspace OOM to GC heuristics if class unloading is possible.
1024 if (heuristics()->can_unload_classes()) {
1025 ShenandoahHeuristics* h = heuristics();
1026 h->record_metaspace_oom();
1027 }
1028
1029 // Expand and retry allocation
1030 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
1031 if (result != nullptr) {
1032 return result;
1033 }
1034
1035 // Start full GC
1036 collect(GCCause::_metadata_GC_clear_soft_refs);
1037
1038 // Retry allocation
1039 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
1040 if (result != nullptr) {
1041 return result;
1042 }
1043
1044 // Expand and retry allocation
1045 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
1046 if (result != nullptr) {
1047 return result;
1048 }
1049
1050 // Out of memory
1051 return nullptr;
1052 }
1053
1054 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
1055 private:
1056 ShenandoahHeap* const _heap;
1057 Thread* const _thread;
1058 public:
1059 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
1060 _heap(heap), _thread(Thread::current()) {}
1061
1062 void do_object(oop p) {
1063 shenandoah_assert_marked(nullptr, p);
1064 if (!p->is_forwarded()) {
1065 _heap->evacuate_object(p, _thread);
1066 }
1067 }
1068 };
1069
1070 class ShenandoahEvacuationTask : public WorkerTask {
1071 private:
1072 ShenandoahHeap* const _sh;
1073 ShenandoahCollectionSet* const _cs;
1074 bool _concurrent;
1075 public:
1076 ShenandoahEvacuationTask(ShenandoahHeap* sh,
1077 ShenandoahCollectionSet* cs,
1078 bool concurrent) :
1079 WorkerTask("Shenandoah Evacuation"),
1080 _sh(sh),
1081 _cs(cs),
1082 _concurrent(concurrent)
1083 {}
1084
1085 void work(uint worker_id) {
1086 if (_concurrent) {
1087 ShenandoahConcurrentWorkerSession worker_session(worker_id);
1088 ShenandoahSuspendibleThreadSetJoiner stsj;
1089 ShenandoahEvacOOMScope oom_evac_scope;
1090 do_work();
1091 } else {
1092 ShenandoahParallelWorkerSession worker_session(worker_id);
1093 ShenandoahEvacOOMScope oom_evac_scope;
1094 do_work();
1095 }
1096 }
1097
1098 private:
1099 void do_work() {
1100 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
1101 ShenandoahHeapRegion* r;
1102 while ((r =_cs->claim_next()) != nullptr) {
1103 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
1104 _sh->marked_object_iterate(r, &cl);
1105
1106 if (ShenandoahPacing) {
1107 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
1108 }
1109
1110 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1111 break;
1112 }
1113 }
1114 }
1115 };
1116
1117 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
1118 ShenandoahEvacuationTask task(this, _collection_set, concurrent);
1119 workers()->run_task(&task);
1120 }
1121
1122 oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {
1123 if (ShenandoahThreadLocalData::is_oom_during_evac(Thread::current())) {
1124 // This thread went through the OOM during evac protocol and it is safe to return
1125 // the forward pointer. It must not attempt to evacuate any more.
1126 return ShenandoahBarrierSet::resolve_forwarded(p);
1127 }
1128
1129 assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope");
1130
1131 size_t size = p->size();
1132
1133 assert(!heap_region_containing(p)->is_humongous(), "never evacuate humongous objects");
1134
1135 bool alloc_from_gclab = true;
1136 HeapWord* copy = nullptr;
1137
1138 #ifdef ASSERT
1139 if (ShenandoahOOMDuringEvacALot &&
1140 (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call
1141 copy = nullptr;
1142 } else {
1143 #endif
1144 if (UseTLAB) {
1145 copy = allocate_from_gclab(thread, size);
1146 }
1147 if (copy == nullptr) {
1148 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size);
1149 copy = allocate_memory(req);
1150 alloc_from_gclab = false;
1151 }
1152 #ifdef ASSERT
1153 }
1154 #endif
1155
1156 if (copy == nullptr) {
1157 control_thread()->handle_alloc_failure_evac(size);
1158
1159 _oom_evac_handler.handle_out_of_memory_during_evacuation();
1160
1161 return ShenandoahBarrierSet::resolve_forwarded(p);
1162 }
1163
1164 // Copy the object:
1165 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(p), copy, size);
1166
1167 // Try to install the new forwarding pointer.
1168 oop copy_val = cast_to_oop(copy);
1169 ContinuationGCSupport::relativize_stack_chunk(copy_val);
1170
1171 oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val);
1172 if (result == copy_val) {
1173 // Successfully evacuated. Our copy is now the public one!
1174 shenandoah_assert_correct(nullptr, copy_val);
1175 return copy_val;
1176 } else {
1177 // Failed to evacuate. We need to deal with the object that is left behind. Since this
1178 // new allocation is certainly after TAMS, it will be considered live in the next cycle.
1179 // But if it happens to contain references to evacuated regions, those references would
1180 // not get updated for this stale copy during this cycle, and we will crash while scanning
1181 // it the next cycle.
1182 //
1183 // For GCLAB allocations, it is enough to rollback the allocation ptr. Either the next
1184 // object will overwrite this stale copy, or the filler object on LAB retirement will
1185 // do this. For non-GCLAB allocations, we have no way to retract the allocation, and
1186 // have to explicitly overwrite the copy with the filler object. With that overwrite,
1187 // we have to keep the fwdptr initialized and pointing to our (stale) copy.
1188 if (alloc_from_gclab) {
1189 ShenandoahThreadLocalData::gclab(thread)->undo_allocation(copy, size);
1190 } else {
1191 fill_with_object(copy, size);
1192 shenandoah_assert_correct(nullptr, copy_val);
1193 }
1194 shenandoah_assert_correct(nullptr, result);
1195 return result;
1196 }
1197 }
1198
1199 void ShenandoahHeap::trash_cset_regions() {
1200 ShenandoahHeapLocker locker(lock());
1201
1202 ShenandoahCollectionSet* set = collection_set();
1203 ShenandoahHeapRegion* r;
1204 set->clear_current_index();
1205 while ((r = set->next()) != nullptr) {
1206 r->make_trash();
1207 }
1208 collection_set()->clear();
1209 }
1210
1211 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1212 st->print_cr("Heap Regions:");
1213 st->print_cr("Region state: EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HP=pinned humongous start");
1214 st->print_cr(" HC=humongous continuation, CS=collection set, TR=trash, P=pinned, CSP=pinned collection set");
1215 st->print_cr("BTE=bottom/top/end, TAMS=top-at-mark-start");
1216 st->print_cr("UWM=update watermark, U=used");
1217 st->print_cr("T=TLAB allocs, G=GCLAB allocs");
1218 st->print_cr("S=shared allocs, L=live data");
1219 st->print_cr("CP=critical pins");
1220
1221 for (size_t i = 0; i < num_regions(); i++) {
1222 get_region(i)->print_on(st);
1223 }
1224 }
1225
1226 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1227 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1228
1229 oop humongous_obj = cast_to_oop(start->bottom());
1230 size_t size = humongous_obj->size();
1231 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1232 size_t index = start->index() + required_regions - 1;
1233
1234 assert(!start->has_live(), "liveness must be zero");
1235
1236 for(size_t i = 0; i < required_regions; i++) {
1237 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1238 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1239 ShenandoahHeapRegion* region = get_region(index --);
1240
1241 assert(region->is_humongous(), "expect correct humongous start or continuation");
1242 assert(!region->is_cset(), "Humongous region should not be in collection set");
1243
1244 region->make_trash_immediate();
1245 }
1246 }
1247
1248 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1249 public:
1250 ShenandoahCheckCleanGCLABClosure() {}
1251 void do_thread(Thread* thread) {
1252 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1253 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1254 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1255 }
1256 };
1257
1258 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1259 private:
1260 bool const _resize;
1261 public:
1262 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1263 void do_thread(Thread* thread) {
1264 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1265 assert(gclab != nullptr, "GCLAB should be initialized for %s", thread->name());
1266 gclab->retire();
1267 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1268 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1269 }
1270 }
1271 };
1272
1273 void ShenandoahHeap::labs_make_parsable() {
1274 assert(UseTLAB, "Only call with UseTLAB");
1275
1276 ShenandoahRetireGCLABClosure cl(false);
1277
1278 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1279 ThreadLocalAllocBuffer& tlab = t->tlab();
1280 tlab.make_parsable();
1281 cl.do_thread(t);
1282 }
1283
1284 workers()->threads_do(&cl);
1285 }
1286
1287 void ShenandoahHeap::tlabs_retire(bool resize) {
1288 assert(UseTLAB, "Only call with UseTLAB");
1289 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1290
1291 ThreadLocalAllocStats stats;
1292
1293 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1294 ThreadLocalAllocBuffer& tlab = t->tlab();
1295 tlab.retire(&stats);
1296 if (resize) {
1297 tlab.resize();
1298 }
1299 }
1300
1301 stats.publish();
1302
1303 #ifdef ASSERT
1304 ShenandoahCheckCleanGCLABClosure cl;
1305 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1306 cl.do_thread(t);
1307 }
1308 workers()->threads_do(&cl);
1309 #endif
1310 }
1311
1312 void ShenandoahHeap::gclabs_retire(bool resize) {
1313 assert(UseTLAB, "Only call with UseTLAB");
1314 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1315
1316 ShenandoahRetireGCLABClosure cl(resize);
1317 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1318 cl.do_thread(t);
1319 }
1320 workers()->threads_do(&cl);
1321
1322 if (safepoint_workers() != nullptr) {
1323 safepoint_workers()->threads_do(&cl);
1324 }
1325 }
1326
1327 // Returns size in bytes
1328 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1329 // Return the max allowed size, and let the allocation path
1330 // figure out the safe size for current allocation.
1331 return ShenandoahHeapRegion::max_tlab_size_bytes();
1332 }
1333
1334 size_t ShenandoahHeap::max_tlab_size() const {
1335 // Returns size in words
1336 return ShenandoahHeapRegion::max_tlab_size_words();
1337 }
1338
1339 void ShenandoahHeap::collect(GCCause::Cause cause) {
1340 control_thread()->request_gc(cause);
1341 }
1342
1343 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1344 //assert(false, "Shouldn't need to do full collections");
1345 }
1346
1347 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1348 ShenandoahHeapRegion* r = heap_region_containing(addr);
1349 if (r != nullptr) {
1350 return r->block_start(addr);
1351 }
1352 return nullptr;
1353 }
1354
1355 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1356 ShenandoahHeapRegion* r = heap_region_containing(addr);
1357 return r->block_is_obj(addr);
1358 }
1359
1360 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1361 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1362 }
1363
1364 void ShenandoahHeap::prepare_for_verify() {
1365 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1366 labs_make_parsable();
1367 }
1368 }
1369
1370 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1371 if (_shenandoah_policy->is_at_shutdown()) {
1372 return;
1373 }
1374
1375 if (_control_thread != nullptr) {
1376 tcl->do_thread(_control_thread);
1377 }
1378
1379 workers()->threads_do(tcl);
1380 if (_safepoint_workers != nullptr) {
1381 _safepoint_workers->threads_do(tcl);
1382 }
1383 }
1384
1385 void ShenandoahHeap::print_tracing_info() const {
1386 LogTarget(Info, gc, stats) lt;
1387 if (lt.is_enabled()) {
1388 ResourceMark rm;
1389 LogStream ls(lt);
1390
1391 phase_timings()->print_global_on(&ls);
1392
1393 ls.cr();
1394 ls.cr();
1395
1396 shenandoah_policy()->print_gc_stats(&ls);
1397
1398 ls.cr();
1399 ls.cr();
1400 }
1401 }
1402
1403 void ShenandoahHeap::verify(VerifyOption vo) {
1404 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1405 if (ShenandoahVerify) {
1406 verifier()->verify_generic(vo);
1407 } else {
1408 // TODO: Consider allocating verification bitmaps on demand,
1409 // and turn this on unconditionally.
1410 }
1411 }
1412 }
1413 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1414 return _free_set->capacity();
1415 }
1416
1417 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1418 private:
1419 MarkBitMap* _bitmap;
1420 ShenandoahScanObjectStack* _oop_stack;
1421 ShenandoahHeap* const _heap;
1422 ShenandoahMarkingContext* const _marking_context;
1423
1424 template <class T>
1425 void do_oop_work(T* p) {
1426 T o = RawAccess<>::oop_load(p);
1427 if (!CompressedOops::is_null(o)) {
1428 oop obj = CompressedOops::decode_not_null(o);
1429 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1430 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1431 return;
1432 }
1433 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1434
1435 assert(oopDesc::is_oop(obj), "must be a valid oop");
1436 if (!_bitmap->is_marked(obj)) {
1437 _bitmap->mark(obj);
1438 _oop_stack->push(obj);
1439 }
1440 }
1441 }
1442 public:
1443 ObjectIterateScanRootClosure(MarkBitMap* bitmap, ShenandoahScanObjectStack* oop_stack) :
1444 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1445 _marking_context(_heap->marking_context()) {}
1446 void do_oop(oop* p) { do_oop_work(p); }
1447 void do_oop(narrowOop* p) { do_oop_work(p); }
1448 };
1449
1450 /*
1451 * This is public API, used in preparation of object_iterate().
1452 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1453 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1454 * control, we call SH::tlabs_retire, SH::gclabs_retire.
1455 */
1456 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1457 // No-op.
1458 }
1459
1460 /*
1461 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1462 *
1463 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1464 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1465 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1466 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1467 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1468 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1469 * wiped the bitmap in preparation for next marking).
1470 *
1471 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1472 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1473 * is allowed to report dead objects, but is not required to do so.
1474 */
1475 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1476 // Reset bitmap
1477 if (!prepare_aux_bitmap_for_iteration())
1478 return;
1479
1480 ShenandoahScanObjectStack oop_stack;
1481 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1482 // Seed the stack with root scan
1483 scan_roots_for_iteration(&oop_stack, &oops);
1484
1485 // Work through the oop stack to traverse heap
1486 while (! oop_stack.is_empty()) {
1487 oop obj = oop_stack.pop();
1488 assert(oopDesc::is_oop(obj), "must be a valid oop");
1489 cl->do_object(obj);
1490 obj->oop_iterate(&oops);
1491 }
1492
1493 assert(oop_stack.is_empty(), "should be empty");
1494 // Reclaim bitmap
1495 reclaim_aux_bitmap_for_iteration();
1496 }
1497
1498 bool ShenandoahHeap::prepare_aux_bitmap_for_iteration() {
1499 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1500
1501 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1502 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1503 return false;
1504 }
1505 // Reset bitmap
1506 _aux_bit_map.clear();
1507 return true;
1508 }
1509
1510 void ShenandoahHeap::scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops) {
1511 // Process GC roots according to current GC cycle
1512 // This populates the work stack with initial objects
1513 // It is important to relinquish the associated locks before diving
1514 // into heap dumper
1515 uint n_workers = safepoint_workers() != nullptr ? safepoint_workers()->active_workers() : 1;
1516 ShenandoahHeapIterationRootScanner rp(n_workers);
1517 rp.roots_do(oops);
1518 }
1519
1520 void ShenandoahHeap::reclaim_aux_bitmap_for_iteration() {
1521 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1522 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1523 }
1524 }
1525
1526 // Closure for parallelly iterate objects
1527 class ShenandoahObjectIterateParScanClosure : public BasicOopIterateClosure {
1528 private:
1529 MarkBitMap* _bitmap;
1530 ShenandoahObjToScanQueue* _queue;
1531 ShenandoahHeap* const _heap;
1532 ShenandoahMarkingContext* const _marking_context;
1533
1534 template <class T>
1535 void do_oop_work(T* p) {
1536 T o = RawAccess<>::oop_load(p);
1537 if (!CompressedOops::is_null(o)) {
1538 oop obj = CompressedOops::decode_not_null(o);
1539 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1540 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1541 return;
1542 }
1543 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
1544
1545 assert(oopDesc::is_oop(obj), "Must be a valid oop");
1546 if (_bitmap->par_mark(obj)) {
1547 _queue->push(ShenandoahMarkTask(obj));
1548 }
1549 }
1550 }
1551 public:
1552 ShenandoahObjectIterateParScanClosure(MarkBitMap* bitmap, ShenandoahObjToScanQueue* q) :
1553 _bitmap(bitmap), _queue(q), _heap(ShenandoahHeap::heap()),
1554 _marking_context(_heap->marking_context()) {}
1555 void do_oop(oop* p) { do_oop_work(p); }
1556 void do_oop(narrowOop* p) { do_oop_work(p); }
1557 };
1558
1559 // Object iterator for parallel heap iteraion.
1560 // The root scanning phase happenes in construction as a preparation of
1561 // parallel marking queues.
1562 // Every worker processes it's own marking queue. work-stealing is used
1563 // to balance workload.
1564 class ShenandoahParallelObjectIterator : public ParallelObjectIteratorImpl {
1565 private:
1566 uint _num_workers;
1567 bool _init_ready;
1568 MarkBitMap* _aux_bit_map;
1569 ShenandoahHeap* _heap;
1570 ShenandoahScanObjectStack _roots_stack; // global roots stack
1571 ShenandoahObjToScanQueueSet* _task_queues;
1572 public:
1573 ShenandoahParallelObjectIterator(uint num_workers, MarkBitMap* bitmap) :
1574 _num_workers(num_workers),
1575 _init_ready(false),
1576 _aux_bit_map(bitmap),
1577 _heap(ShenandoahHeap::heap()) {
1578 // Initialize bitmap
1579 _init_ready = _heap->prepare_aux_bitmap_for_iteration();
1580 if (!_init_ready) {
1581 return;
1582 }
1583
1584 ObjectIterateScanRootClosure oops(_aux_bit_map, &_roots_stack);
1585 _heap->scan_roots_for_iteration(&_roots_stack, &oops);
1586
1587 _init_ready = prepare_worker_queues();
1588 }
1589
1590 ~ShenandoahParallelObjectIterator() {
1591 // Reclaim bitmap
1592 _heap->reclaim_aux_bitmap_for_iteration();
1593 // Reclaim queue for workers
1594 if (_task_queues!= nullptr) {
1595 for (uint i = 0; i < _num_workers; ++i) {
1596 ShenandoahObjToScanQueue* q = _task_queues->queue(i);
1597 if (q != nullptr) {
1598 delete q;
1599 _task_queues->register_queue(i, nullptr);
1600 }
1601 }
1602 delete _task_queues;
1603 _task_queues = nullptr;
1604 }
1605 }
1606
1607 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
1608 if (_init_ready) {
1609 object_iterate_parallel(cl, worker_id, _task_queues);
1610 }
1611 }
1612
1613 private:
1614 // Divide global root_stack into worker queues
1615 bool prepare_worker_queues() {
1616 _task_queues = new ShenandoahObjToScanQueueSet((int) _num_workers);
1617 // Initialize queues for every workers
1618 for (uint i = 0; i < _num_workers; ++i) {
1619 ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue();
1620 _task_queues->register_queue(i, task_queue);
1621 }
1622 // Divide roots among the workers. Assume that object referencing distribution
1623 // is related with root kind, use round-robin to make every worker have same chance
1624 // to process every kind of roots
1625 size_t roots_num = _roots_stack.size();
1626 if (roots_num == 0) {
1627 // No work to do
1628 return false;
1629 }
1630
1631 for (uint j = 0; j < roots_num; j++) {
1632 uint stack_id = j % _num_workers;
1633 oop obj = _roots_stack.pop();
1634 _task_queues->queue(stack_id)->push(ShenandoahMarkTask(obj));
1635 }
1636 return true;
1637 }
1638
1639 void object_iterate_parallel(ObjectClosure* cl,
1640 uint worker_id,
1641 ShenandoahObjToScanQueueSet* queue_set) {
1642 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1643 assert(queue_set != nullptr, "task queue must not be null");
1644
1645 ShenandoahObjToScanQueue* q = queue_set->queue(worker_id);
1646 assert(q != nullptr, "object iterate queue must not be null");
1647
1648 ShenandoahMarkTask t;
1649 ShenandoahObjectIterateParScanClosure oops(_aux_bit_map, q);
1650
1651 // Work through the queue to traverse heap.
1652 // Steal when there is no task in queue.
1653 while (q->pop(t) || queue_set->steal(worker_id, t)) {
1654 oop obj = t.obj();
1655 assert(oopDesc::is_oop(obj), "must be a valid oop");
1656 cl->do_object(obj);
1657 obj->oop_iterate(&oops);
1658 }
1659 assert(q->is_empty(), "should be empty");
1660 }
1661 };
1662
1663 ParallelObjectIteratorImpl* ShenandoahHeap::parallel_object_iterator(uint workers) {
1664 return new ShenandoahParallelObjectIterator(workers, &_aux_bit_map);
1665 }
1666
1667 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1668 void ShenandoahHeap::keep_alive(oop obj) {
1669 if (is_concurrent_mark_in_progress() && (obj != nullptr)) {
1670 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1671 }
1672 }
1673
1674 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1675 for (size_t i = 0; i < num_regions(); i++) {
1676 ShenandoahHeapRegion* current = get_region(i);
1677 blk->heap_region_do(current);
1678 }
1679 }
1680
1681 class ShenandoahParallelHeapRegionTask : public WorkerTask {
1682 private:
1683 ShenandoahHeap* const _heap;
1684 ShenandoahHeapRegionClosure* const _blk;
1685
1686 shenandoah_padding(0);
1687 volatile size_t _index;
1688 shenandoah_padding(1);
1689
1690 public:
1691 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1692 WorkerTask("Shenandoah Parallel Region Operation"),
1693 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1694
1695 void work(uint worker_id) {
1696 ShenandoahParallelWorkerSession worker_session(worker_id);
1697 size_t stride = ShenandoahParallelRegionStride;
1698
1699 size_t max = _heap->num_regions();
1700 while (Atomic::load(&_index) < max) {
1701 size_t cur = Atomic::fetch_then_add(&_index, stride, memory_order_relaxed);
1702 size_t start = cur;
1703 size_t end = MIN2(cur + stride, max);
1704 if (start >= max) break;
1705
1706 for (size_t i = cur; i < end; i++) {
1707 ShenandoahHeapRegion* current = _heap->get_region(i);
1708 _blk->heap_region_do(current);
1709 }
1710 }
1711 }
1712 };
1713
1714 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1715 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1716 if (num_regions() > ShenandoahParallelRegionStride) {
1717 ShenandoahParallelHeapRegionTask task(blk);
1718 workers()->run_task(&task);
1719 } else {
1720 heap_region_iterate(blk);
1721 }
1722 }
1723
1724 class ShenandoahRendezvousClosure : public HandshakeClosure {
1725 public:
1726 inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
1727 inline void do_thread(Thread* thread) {}
1728 };
1729
1730 void ShenandoahHeap::rendezvous_threads() {
1731 ShenandoahRendezvousClosure cl;
1732 Handshake::execute(&cl);
1733 }
1734
1735 void ShenandoahHeap::recycle_trash() {
1736 free_set()->recycle_trash();
1737 }
1738
1739 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1740 private:
1741 ShenandoahMarkingContext* const _ctx;
1742 public:
1743 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1744
1745 void heap_region_do(ShenandoahHeapRegion* r) {
1746 if (r->is_active()) {
1747 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1748 // anyway to capture any updates that happened since now.
1749 r->clear_live_data();
1750 _ctx->capture_top_at_mark_start(r);
1751 }
1752 }
1753
1754 bool is_thread_safe() { return true; }
1755 };
1756
1757 void ShenandoahHeap::prepare_gc() {
1758 reset_mark_bitmap();
1759
1760 ShenandoahResetUpdateRegionStateClosure cl;
1761 parallel_heap_region_iterate(&cl);
1762 }
1763
1764 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1765 private:
1766 ShenandoahMarkingContext* const _ctx;
1767 ShenandoahHeapLock* const _lock;
1768
1769 public:
1770 ShenandoahFinalMarkUpdateRegionStateClosure() :
1771 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1772
1773 void heap_region_do(ShenandoahHeapRegion* r) {
1774 if (r->is_active()) {
1775 // All allocations past TAMS are implicitly live, adjust the region data.
1776 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1777 HeapWord *tams = _ctx->top_at_mark_start(r);
1778 HeapWord *top = r->top();
1779 if (top > tams) {
1780 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1781 }
1782
1783 // We are about to select the collection set, make sure it knows about
1784 // current pinning status. Also, this allows trashing more regions that
1785 // now have their pinning status dropped.
1786 if (r->is_pinned()) {
1787 if (r->pin_count() == 0) {
1788 ShenandoahHeapLocker locker(_lock);
1789 r->make_unpinned();
1790 }
1791 } else {
1792 if (r->pin_count() > 0) {
1793 ShenandoahHeapLocker locker(_lock);
1794 r->make_pinned();
1795 }
1796 }
1797
1798 // Remember limit for updating refs. It's guaranteed that we get no
1799 // from-space-refs written from here on.
1800 r->set_update_watermark_at_safepoint(r->top());
1801 } else {
1802 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1803 assert(_ctx->top_at_mark_start(r) == r->top(),
1804 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1805 }
1806 }
1807
1808 bool is_thread_safe() { return true; }
1809 };
1810
1811 void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) {
1812 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
1813 {
1814 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states :
1815 ShenandoahPhaseTimings::degen_gc_final_update_region_states);
1816 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1817 parallel_heap_region_iterate(&cl);
1818
1819 assert_pinned_region_status();
1820 }
1821
1822 {
1823 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset :
1824 ShenandoahPhaseTimings::degen_gc_choose_cset);
1825 ShenandoahHeapLocker locker(lock());
1826 _collection_set->clear();
1827 heuristics()->choose_collection_set(_collection_set);
1828 }
1829
1830 {
1831 ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset :
1832 ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset);
1833 ShenandoahHeapLocker locker(lock());
1834 _free_set->rebuild();
1835 }
1836 }
1837
1838 void ShenandoahHeap::do_class_unloading() {
1839 _unloader.unload();
1840 }
1841
1842 void ShenandoahHeap::stw_weak_refs(bool full_gc) {
1843 // Weak refs processing
1844 ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
1845 : ShenandoahPhaseTimings::degen_gc_weakrefs;
1846 ShenandoahTimingsTracker t(phase);
1847 ShenandoahGCWorkerPhase worker_phase(phase);
1848 ref_processor()->process_references(phase, workers(), false /* concurrent */);
1849 }
1850
1851 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
1852 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1853
1854 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
1855 // make them parsable for update code to work correctly. Plus, we can compute new sizes
1856 // for future GCLABs here.
1857 if (UseTLAB) {
1858 ShenandoahGCPhase phase(concurrent ?
1859 ShenandoahPhaseTimings::init_update_refs_manage_gclabs :
1860 ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs);
1861 gclabs_retire(ResizeTLAB);
1862 }
1863
1864 _update_refs_iterator.reset();
1865 }
1866
1867 void ShenandoahHeap::propagate_gc_state_to_java_threads() {
1868 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint");
1869 if (_gc_state_changed) {
1870 _gc_state_changed = false;
1871 char state = gc_state();
1872 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1873 ShenandoahThreadLocalData::set_gc_state(t, state);
1874 }
1875 }
1876 }
1877
1878 void ShenandoahHeap::set_gc_state(uint mask, bool value) {
1879 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at Shenandoah safepoint");
1880 _gc_state.set_cond(mask, value);
1881 _gc_state_changed = true;
1882 }
1883
1884 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1885 assert(!has_forwarded_objects(), "Not expected before/after mark phase");
1886 set_gc_state(MARKING, in_progress);
1887 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1888 }
1889
1890 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1891 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1892 set_gc_state(EVACUATION, in_progress);
1893 }
1894
1895 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
1896 if (in_progress) {
1897 _concurrent_strong_root_in_progress.set();
1898 } else {
1899 _concurrent_strong_root_in_progress.unset();
1900 }
1901 }
1902
1903 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) {
1904 set_gc_state(WEAK_ROOTS, cond);
1905 }
1906
1907 GCTracer* ShenandoahHeap::tracer() {
1908 return shenandoah_policy()->tracer();
1909 }
1910
1911 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1912 return _free_set->used();
1913 }
1914
1915 bool ShenandoahHeap::try_cancel_gc() {
1916 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1917 return prev == CANCELLABLE;
1918 }
1919
1920 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1921 if (try_cancel_gc()) {
1922 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1923 log_info(gc)("%s", msg.buffer());
1924 Events::log(Thread::current(), "%s", msg.buffer());
1925 }
1926 }
1927
1928 uint ShenandoahHeap::max_workers() {
1929 return _max_workers;
1930 }
1931
1932 void ShenandoahHeap::stop() {
1933 // The shutdown sequence should be able to terminate when GC is running.
1934
1935 // Step 0. Notify policy to disable event recording and prevent visiting gc threads during shutdown
1936 _shenandoah_policy->record_shutdown();
1937
1938 // Step 1. Notify control thread that we are in shutdown.
1939 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1940 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1941 control_thread()->prepare_for_graceful_shutdown();
1942
1943 // Step 2. Notify GC workers that we are cancelling GC.
1944 cancel_gc(GCCause::_shenandoah_stop_vm);
1945
1946 // Step 3. Wait until GC worker exits normally.
1947 control_thread()->stop();
1948 }
1949
1950 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
1951 if (!unload_classes()) return;
1952 ClassUnloadingContext ctx(_workers->active_workers(),
1953 true /* unregister_nmethods_during_purge */,
1954 false /* lock_nmethod_free_separately */);
1955
1956 // Unload classes and purge SystemDictionary.
1957 {
1958 ShenandoahPhaseTimings::Phase phase = full_gc ?
1959 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1960 ShenandoahPhaseTimings::degen_gc_purge_class_unload;
1961 ShenandoahIsAliveSelector is_alive;
1962 {
1963 CodeCache::UnlinkingScope scope(is_alive.is_alive_closure());
1964 ShenandoahGCPhase gc_phase(phase);
1965 ShenandoahGCWorkerPhase worker_phase(phase);
1966 bool unloading_occurred = SystemDictionary::do_unloading(gc_timer());
1967
1968 uint num_workers = _workers->active_workers();
1969 ShenandoahClassUnloadingTask unlink_task(phase, num_workers, unloading_occurred);
1970 _workers->run_task(&unlink_task);
1971 }
1972 // Release unloaded nmethods's memory.
1973 ClassUnloadingContext::context()->purge_and_free_nmethods();
1974 }
1975
1976 {
1977 ShenandoahGCPhase phase(full_gc ?
1978 ShenandoahPhaseTimings::full_gc_purge_cldg :
1979 ShenandoahPhaseTimings::degen_gc_purge_cldg);
1980 ClassLoaderDataGraph::purge(true /* at_safepoint */);
1981 }
1982 // Resize and verify metaspace
1983 MetaspaceGC::compute_new_size();
1984 DEBUG_ONLY(MetaspaceUtils::verify();)
1985 }
1986
1987 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
1988 // so they should not have forwarded oops.
1989 // However, we do need to "null" dead oops in the roots, if can not be done
1990 // in concurrent cycles.
1991 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
1992 uint num_workers = _workers->active_workers();
1993 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
1994 ShenandoahPhaseTimings::full_gc_purge_weak_par :
1995 ShenandoahPhaseTimings::degen_gc_purge_weak_par;
1996 ShenandoahGCPhase phase(timing_phase);
1997 ShenandoahGCWorkerPhase worker_phase(timing_phase);
1998 // Cleanup weak roots
1999 if (has_forwarded_objects()) {
2000 ShenandoahForwardedIsAliveClosure is_alive;
2001 ShenandoahUpdateRefsClosure keep_alive;
2002 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2003 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers);
2004 _workers->run_task(&cleaning_task);
2005 } else {
2006 ShenandoahIsAliveClosure is_alive;
2007 #ifdef ASSERT
2008 ShenandoahAssertNotForwardedClosure verify_cl;
2009 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2010 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers);
2011 #else
2012 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2013 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers);
2014 #endif
2015 _workers->run_task(&cleaning_task);
2016 }
2017 }
2018
2019 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2020 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2021 assert(is_stw_gc_in_progress(), "Only for Degenerated and Full GC");
2022 ShenandoahGCPhase phase(full_gc ?
2023 ShenandoahPhaseTimings::full_gc_purge :
2024 ShenandoahPhaseTimings::degen_gc_purge);
2025 stw_weak_refs(full_gc);
2026 stw_process_weak_roots(full_gc);
2027 stw_unload_classes(full_gc);
2028 }
2029
2030 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2031 set_gc_state(HAS_FORWARDED, cond);
2032 }
2033
2034 void ShenandoahHeap::set_unload_classes(bool uc) {
2035 _unload_classes.set_cond(uc);
2036 }
2037
2038 bool ShenandoahHeap::unload_classes() const {
2039 return _unload_classes.is_set();
2040 }
2041
2042 address ShenandoahHeap::in_cset_fast_test_addr() {
2043 ShenandoahHeap* heap = ShenandoahHeap::heap();
2044 assert(heap->collection_set() != nullptr, "Sanity");
2045 return (address) heap->collection_set()->biased_map_address();
2046 }
2047
2048 size_t ShenandoahHeap::bytes_allocated_since_gc_start() const {
2049 return Atomic::load(&_bytes_allocated_since_gc_start);
2050 }
2051
2052 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2053 Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0);
2054 }
2055
2056 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2057 _degenerated_gc_in_progress.set_cond(in_progress);
2058 }
2059
2060 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2061 _full_gc_in_progress.set_cond(in_progress);
2062 }
2063
2064 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2065 assert (is_full_gc_in_progress(), "should be");
2066 _full_gc_move_in_progress.set_cond(in_progress);
2067 }
2068
2069 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2070 set_gc_state(UPDATEREFS, in_progress);
2071 }
2072
2073 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2074 ShenandoahCodeRoots::register_nmethod(nm);
2075 }
2076
2077 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2078 ShenandoahCodeRoots::unregister_nmethod(nm);
2079 }
2080
2081 void ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2082 heap_region_containing(o)->record_pin();
2083 }
2084
2085 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2086 ShenandoahHeapRegion* r = heap_region_containing(o);
2087 assert(r != nullptr, "Sanity");
2088 assert(r->pin_count() > 0, "Region " SIZE_FORMAT " should have non-zero pins", r->index());
2089 r->record_unpin();
2090 }
2091
2092 void ShenandoahHeap::sync_pinned_region_status() {
2093 ShenandoahHeapLocker locker(lock());
2094
2095 for (size_t i = 0; i < num_regions(); i++) {
2096 ShenandoahHeapRegion *r = get_region(i);
2097 if (r->is_active()) {
2098 if (r->is_pinned()) {
2099 if (r->pin_count() == 0) {
2100 r->make_unpinned();
2101 }
2102 } else {
2103 if (r->pin_count() > 0) {
2104 r->make_pinned();
2105 }
2106 }
2107 }
2108 }
2109
2110 assert_pinned_region_status();
2111 }
2112
2113 #ifdef ASSERT
2114 void ShenandoahHeap::assert_pinned_region_status() {
2115 for (size_t i = 0; i < num_regions(); i++) {
2116 ShenandoahHeapRegion* r = get_region(i);
2117 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2118 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2119 }
2120 }
2121 #endif
2122
2123 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
2124 return _gc_timer;
2125 }
2126
2127 void ShenandoahHeap::prepare_concurrent_roots() {
2128 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2129 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
2130 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
2131 set_concurrent_weak_root_in_progress(true);
2132 if (unload_classes()) {
2133 _unloader.prepare();
2134 }
2135 }
2136
2137 void ShenandoahHeap::finish_concurrent_roots() {
2138 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2139 assert(!is_stw_gc_in_progress(), "Only concurrent GC");
2140 if (unload_classes()) {
2141 _unloader.finish();
2142 }
2143 }
2144
2145 #ifdef ASSERT
2146 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2147 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2148
2149 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2150 // Use ParallelGCThreads inside safepoints
2151 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads (%u) within safepoint, not %u",
2152 ParallelGCThreads, nworkers);
2153 } else {
2154 // Use ConcGCThreads outside safepoints
2155 assert(nworkers == ConcGCThreads, "Use ConcGCThreads (%u) outside safepoints, %u",
2156 ConcGCThreads, nworkers);
2157 }
2158 }
2159 #endif
2160
2161 ShenandoahVerifier* ShenandoahHeap::verifier() {
2162 guarantee(ShenandoahVerify, "Should be enabled");
2163 assert (_verifier != nullptr, "sanity");
2164 return _verifier;
2165 }
2166
2167 template<bool CONCURRENT>
2168 class ShenandoahUpdateHeapRefsTask : public WorkerTask {
2169 private:
2170 ShenandoahHeap* _heap;
2171 ShenandoahRegionIterator* _regions;
2172 public:
2173 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
2174 WorkerTask("Shenandoah Update References"),
2175 _heap(ShenandoahHeap::heap()),
2176 _regions(regions) {
2177 }
2178
2179 void work(uint worker_id) {
2180 if (CONCURRENT) {
2181 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2182 ShenandoahSuspendibleThreadSetJoiner stsj;
2183 do_work<ShenandoahConcUpdateRefsClosure>(worker_id);
2184 } else {
2185 ShenandoahParallelWorkerSession worker_session(worker_id);
2186 do_work<ShenandoahSTWUpdateRefsClosure>(worker_id);
2187 }
2188 }
2189
2190 private:
2191 template<class T>
2192 void do_work(uint worker_id) {
2193 T cl;
2194 if (CONCURRENT && (worker_id == 0)) {
2195 // We ask the first worker to replenish the Mutator free set by moving regions previously reserved to hold the
2196 // results of evacuation. These reserves are no longer necessary because evacuation has completed.
2197 size_t cset_regions = _heap->collection_set()->count();
2198 // We cannot transfer any more regions than will be reclaimed when the existing collection set is recycled because
2199 // we need the reclaimed collection set regions to replenish the collector reserves
2200 _heap->free_set()->move_regions_from_collector_to_mutator(cset_regions);
2201 }
2202 // If !CONCURRENT, there's no value in expanding Mutator free set
2203
2204 ShenandoahHeapRegion* r = _regions->next();
2205 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2206 while (r != nullptr) {
2207 HeapWord* update_watermark = r->get_update_watermark();
2208 assert (update_watermark >= r->bottom(), "sanity");
2209 if (r->is_active() && !r->is_cset()) {
2210 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2211 }
2212 if (ShenandoahPacing) {
2213 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2214 }
2215 if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2216 return;
2217 }
2218 r = _regions->next();
2219 }
2220 }
2221 };
2222
2223 void ShenandoahHeap::update_heap_references(bool concurrent) {
2224 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2225
2226 if (concurrent) {
2227 ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator);
2228 workers()->run_task(&task);
2229 } else {
2230 ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
2231 workers()->run_task(&task);
2232 }
2233 }
2234
2235
2236 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2237 private:
2238 ShenandoahHeapLock* const _lock;
2239
2240 public:
2241 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2242
2243 void heap_region_do(ShenandoahHeapRegion* r) {
2244 // Drop unnecessary "pinned" state from regions that does not have CP marks
2245 // anymore, as this would allow trashing them.
2246
2247 if (r->is_active()) {
2248 if (r->is_pinned()) {
2249 if (r->pin_count() == 0) {
2250 ShenandoahHeapLocker locker(_lock);
2251 r->make_unpinned();
2252 }
2253 } else {
2254 if (r->pin_count() > 0) {
2255 ShenandoahHeapLocker locker(_lock);
2256 r->make_pinned();
2257 }
2258 }
2259 }
2260 }
2261
2262 bool is_thread_safe() { return true; }
2263 };
2264
2265 void ShenandoahHeap::update_heap_region_states(bool concurrent) {
2266 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2267 assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2268
2269 {
2270 ShenandoahGCPhase phase(concurrent ?
2271 ShenandoahPhaseTimings::final_update_refs_update_region_states :
2272 ShenandoahPhaseTimings::degen_gc_final_update_refs_update_region_states);
2273 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2274 parallel_heap_region_iterate(&cl);
2275
2276 assert_pinned_region_status();
2277 }
2278
2279 {
2280 ShenandoahGCPhase phase(concurrent ?
2281 ShenandoahPhaseTimings::final_update_refs_trash_cset :
2282 ShenandoahPhaseTimings::degen_gc_final_update_refs_trash_cset);
2283 trash_cset_regions();
2284 }
2285 }
2286
2287 void ShenandoahHeap::rebuild_free_set(bool concurrent) {
2288 {
2289 ShenandoahGCPhase phase(concurrent ?
2290 ShenandoahPhaseTimings::final_update_refs_rebuild_freeset :
2291 ShenandoahPhaseTimings::degen_gc_final_update_refs_rebuild_freeset);
2292 ShenandoahHeapLocker locker(lock());
2293 _free_set->rebuild();
2294 }
2295 }
2296
2297 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2298 print_on(st);
2299 st->cr();
2300 print_heap_regions_on(st);
2301 }
2302
2303 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2304 size_t slice = r->index() / _bitmap_regions_per_slice;
2305
2306 size_t regions_from = _bitmap_regions_per_slice * slice;
2307 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2308 for (size_t g = regions_from; g < regions_to; g++) {
2309 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2310 if (skip_self && g == r->index()) continue;
2311 if (get_region(g)->is_committed()) {
2312 return true;
2313 }
2314 }
2315 return false;
2316 }
2317
2318 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2319 shenandoah_assert_heaplocked();
2320
2321 // Bitmaps in special regions do not need commits
2322 if (_bitmap_region_special) {
2323 return true;
2324 }
2325
2326 if (is_bitmap_slice_committed(r, true)) {
2327 // Some other region from the group is already committed, meaning the bitmap
2328 // slice is already committed, we exit right away.
2329 return true;
2330 }
2331
2332 // Commit the bitmap slice:
2333 size_t slice = r->index() / _bitmap_regions_per_slice;
2334 size_t off = _bitmap_bytes_per_slice * slice;
2335 size_t len = _bitmap_bytes_per_slice;
2336 char* start = (char*) _bitmap_region.start() + off;
2337
2338 if (!os::commit_memory(start, len, false)) {
2339 return false;
2340 }
2341
2342 if (AlwaysPreTouch) {
2343 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size);
2344 }
2345
2346 return true;
2347 }
2348
2349 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2350 shenandoah_assert_heaplocked();
2351
2352 // Bitmaps in special regions do not need uncommits
2353 if (_bitmap_region_special) {
2354 return true;
2355 }
2356
2357 if (is_bitmap_slice_committed(r, true)) {
2358 // Some other region from the group is still committed, meaning the bitmap
2359 // slice is should stay committed, exit right away.
2360 return true;
2361 }
2362
2363 // Uncommit the bitmap slice:
2364 size_t slice = r->index() / _bitmap_regions_per_slice;
2365 size_t off = _bitmap_bytes_per_slice * slice;
2366 size_t len = _bitmap_bytes_per_slice;
2367 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2368 return false;
2369 }
2370 return true;
2371 }
2372
2373 void ShenandoahHeap::safepoint_synchronize_begin() {
2374 StackWatermarkSet::safepoint_synchronize_begin();
2375 SuspendibleThreadSet::synchronize();
2376 }
2377
2378 void ShenandoahHeap::safepoint_synchronize_end() {
2379 SuspendibleThreadSet::desynchronize();
2380 }
2381
2382 void ShenandoahHeap::try_inject_alloc_failure() {
2383 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2384 _inject_alloc_failure.set();
2385 os::naked_short_sleep(1);
2386 if (cancelled_gc()) {
2387 log_info(gc)("Allocation failure was successfully injected");
2388 }
2389 }
2390 }
2391
2392 bool ShenandoahHeap::should_inject_alloc_failure() {
2393 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2394 }
2395
2396 void ShenandoahHeap::initialize_serviceability() {
2397 _memory_pool = new ShenandoahMemoryPool(this);
2398 _cycle_memory_manager.add_pool(_memory_pool);
2399 _stw_memory_manager.add_pool(_memory_pool);
2400 }
2401
2402 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2403 GrowableArray<GCMemoryManager*> memory_managers(2);
2404 memory_managers.append(&_cycle_memory_manager);
2405 memory_managers.append(&_stw_memory_manager);
2406 return memory_managers;
2407 }
2408
2409 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2410 GrowableArray<MemoryPool*> memory_pools(1);
2411 memory_pools.append(_memory_pool);
2412 return memory_pools;
2413 }
2414
2415 MemoryUsage ShenandoahHeap::memory_usage() {
2416 return _memory_pool->get_memory_usage();
2417 }
2418
2419 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2420 _heap(ShenandoahHeap::heap()),
2421 _index(0) {}
2422
2423 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2424 _heap(heap),
2425 _index(0) {}
2426
2427 void ShenandoahRegionIterator::reset() {
2428 _index = 0;
2429 }
2430
2431 bool ShenandoahRegionIterator::has_next() const {
2432 return _index < _heap->num_regions();
2433 }
2434
2435 char ShenandoahHeap::gc_state() const {
2436 return _gc_state.raw_value();
2437 }
2438
2439 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2440 #ifdef ASSERT
2441 assert(_liveness_cache != nullptr, "sanity");
2442 assert(worker_id < _max_workers, "sanity");
2443 for (uint i = 0; i < num_regions(); i++) {
2444 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2445 }
2446 #endif
2447 return _liveness_cache[worker_id];
2448 }
2449
2450 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2451 assert(worker_id < _max_workers, "sanity");
2452 assert(_liveness_cache != nullptr, "sanity");
2453 ShenandoahLiveData* ld = _liveness_cache[worker_id];
2454 for (uint i = 0; i < num_regions(); i++) {
2455 ShenandoahLiveData live = ld[i];
2456 if (live > 0) {
2457 ShenandoahHeapRegion* r = get_region(i);
2458 r->increase_live_data_gc_words(live);
2459 ld[i] = 0;
2460 }
2461 }
2462 }
2463
2464 bool ShenandoahHeap::requires_barriers(stackChunkOop obj) const {
2465 if (is_idle()) return false;
2466
2467 // Objects allocated after marking start are implicitly alive, don't need any barriers during
2468 // marking phase.
2469 if (is_concurrent_mark_in_progress() &&
2470 !marking_context()->allocated_after_mark_start(obj)) {
2471 return true;
2472 }
2473
2474 // Can not guarantee obj is deeply good.
2475 if (has_forwarded_objects()) {
2476 return true;
2477 }
2478
2479 return false;
2480 }