1 /*
2 * Copyright (c) 2013, 2020, Red Hat, Inc. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.hpp"
27 #include "memory/universe.hpp"
28
29 #include "gc/shared/gcArguments.hpp"
30 #include "gc/shared/gcTimer.hpp"
31 #include "gc/shared/gcTraceTime.inline.hpp"
32 #include "gc/shared/locationPrinter.inline.hpp"
33 #include "gc/shared/memAllocator.hpp"
34 #include "gc/shared/oopStorageSet.hpp"
35 #include "gc/shared/plab.hpp"
36
37 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
38 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
39 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
40 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
41 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
42 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
43 #include "gc/shenandoah/shenandoahControlThread.hpp"
44 #include "gc/shenandoah/shenandoahFreeSet.hpp"
45 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
46 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
47 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
48 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
49 #include "gc/shenandoah/shenandoahMarkCompact.hpp"
50 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
51 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
52 #include "gc/shenandoah/shenandoahMetrics.hpp"
53 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
54 #include "gc/shenandoah/shenandoahNormalMode.hpp"
55 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
56 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
57 #include "gc/shenandoah/shenandoahPadding.hpp"
58 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
59 #include "gc/shenandoah/shenandoahPassiveMode.hpp"
60 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
61 #include "gc/shenandoah/shenandoahStringDedup.hpp"
62 #include "gc/shenandoah/shenandoahTaskqueue.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 #if INCLUDE_JFR
70 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
71 #endif
72
73 #include "memory/metaspace.hpp"
74 #include "oops/compressedOops.inline.hpp"
75 #include "runtime/atomic.hpp"
76 #include "runtime/globals.hpp"
77 #include "runtime/interfaceSupport.inline.hpp"
78 #include "runtime/orderAccess.hpp"
79 #include "runtime/safepointMechanism.hpp"
80 #include "runtime/vmThread.hpp"
81 #include "services/mallocTracker.hpp"
82 #include "utilities/powerOfTwo.hpp"
83
84 ShenandoahHeap* ShenandoahHeap::_heap = NULL;
85
86 #ifdef ASSERT
87 template <class T>
88 void ShenandoahAssertToSpaceClosure::do_oop_work(T* p) {
89 T o = RawAccess<>::oop_load(p);
90 if (! CompressedOops::is_null(o)) {
91 oop obj = CompressedOops::decode_not_null(o);
92 shenandoah_assert_not_forwarded(p, obj);
93 }
94 }
95
96 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_work(p); }
97 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_work(p); }
98 #endif
99
100 class ShenandoahPretouchHeapTask : public AbstractGangTask {
101 private:
102 ShenandoahRegionIterator _regions;
103 const size_t _page_size;
104 public:
105 ShenandoahPretouchHeapTask(size_t page_size) :
106 AbstractGangTask("Shenandoah Pretouch Heap"),
107 _page_size(page_size) {}
108
109 virtual void work(uint worker_id) {
110 ShenandoahHeapRegion* r = _regions.next();
111 while (r != NULL) {
112 os::pretouch_memory(r->bottom(), r->end(), _page_size);
113 r = _regions.next();
114 }
115 }
116 };
117
118 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
119 private:
120 ShenandoahRegionIterator _regions;
121 char* _bitmap_base;
122 const size_t _bitmap_size;
123 const size_t _page_size;
124 public:
125 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
126 AbstractGangTask("Shenandoah Pretouch Bitmap"),
127 _bitmap_base(bitmap_base),
128 _bitmap_size(bitmap_size),
129 _page_size(page_size) {}
130
131 virtual void work(uint worker_id) {
132 ShenandoahHeapRegion* r = _regions.next();
133 while (r != NULL) {
134 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
135 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
136 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
137
138 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
139
140 r = _regions.next();
141 }
142 }
143 };
144
145 jint ShenandoahHeap::initialize() {
146 initialize_heuristics();
147
148 //
149 // Figure out heap sizing
150 //
151
152 size_t init_byte_size = InitialHeapSize;
153 size_t min_byte_size = MinHeapSize;
154 size_t max_byte_size = MaxHeapSize;
155 size_t heap_alignment = HeapAlignment;
156
157 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
158
159 if (ShenandoahAlwaysPreTouch) {
160 // Enabled pre-touch means the entire heap is committed right away.
161 init_byte_size = max_byte_size;
162 }
163
164 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
165 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
166
167 _num_regions = ShenandoahHeapRegion::region_count();
168
169 size_t num_committed_regions = init_byte_size / reg_size_bytes;
170 num_committed_regions = MIN2(num_committed_regions, _num_regions);
171 assert(num_committed_regions <= _num_regions, "sanity");
172 _initial_size = num_committed_regions * reg_size_bytes;
173
174 size_t num_min_regions = min_byte_size / reg_size_bytes;
175 num_min_regions = MIN2(num_min_regions, _num_regions);
176 assert(num_min_regions <= _num_regions, "sanity");
177 _minimum_size = num_min_regions * reg_size_bytes;
178
179 _committed = _initial_size;
180
181 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
182 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
183 size_t region_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)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
197 #if SHENANDOAH_OPTIMIZED_OBJTASK
198 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
199 // Fail if we ever attempt to address more than we can.
200 if ((uintptr_t)heap_rs.end() >= ObjArrayChunkedTask::max_addressable()) {
201 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
202 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
203 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
204 p2i(heap_rs.base()), p2i(heap_rs.end()), ObjArrayChunkedTask::max_addressable());
205 vm_exit_during_initialization("Fatal Error", buf);
206 }
207 #endif
208
209 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
210 if (!_heap_region_special) {
211 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
212 "Cannot commit heap memory");
213 }
214
215 //
216 // Reserve and commit memory for bitmap(s)
217 //
218
219 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
220 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
221
222 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
223
224 guarantee(bitmap_bytes_per_region != 0,
225 "Bitmap bytes per region should not be zero");
226 guarantee(is_power_of_2(bitmap_bytes_per_region),
227 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
228
229 if (bitmap_page_size > bitmap_bytes_per_region) {
230 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
231 _bitmap_bytes_per_slice = bitmap_page_size;
232 } else {
233 _bitmap_regions_per_slice = 1;
234 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
235 }
236
237 guarantee(_bitmap_regions_per_slice >= 1,
238 "Should have at least one region per slice: " SIZE_FORMAT,
239 _bitmap_regions_per_slice);
240
241 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
242 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
243 _bitmap_bytes_per_slice, bitmap_page_size);
244
245 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
246 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
247 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
248 _bitmap_region_special = bitmap.special();
249
250 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
251 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
252 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
253 if (!_bitmap_region_special) {
254 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
255 "Cannot commit bitmap memory");
256 }
257
258 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
259
260 if (ShenandoahVerify) {
261 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
262 if (!verify_bitmap.special()) {
263 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
264 "Cannot commit verification bitmap memory");
265 }
266 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
267 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
268 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
269 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
270 }
271
272 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
273 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
274 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
275 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
276 _aux_bitmap_region_special = aux_bitmap.special();
277 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
278
279 //
280 // Create regions and region sets
281 //
282 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
283 size_t region_storage_size = align_up(region_align * _num_regions, region_page_size);
284
285 ReservedSpace region_storage(region_storage_size, region_page_size);
286 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
287 if (!region_storage.special()) {
288 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
289 "Cannot commit region memory");
290 }
291
292 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
293 _free_set = new ShenandoahFreeSet(this, _num_regions);
294 _collection_set = new ShenandoahCollectionSet(this, sh_rs.base(), sh_rs.size());
295
296 {
297 ShenandoahHeapLocker locker(lock());
298
299 for (size_t i = 0; i < _num_regions; i++) {
300 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
301 bool is_committed = i < num_committed_regions;
302 void* loc = region_storage.base() + i * region_align;
303
304 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
305 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
306
307 _marking_context->initialize_top_at_mark_start(r);
308 _regions[i] = r;
309 assert(!collection_set()->is_in(i), "New region should not be in collection set");
310 }
311
312 // Initialize to complete
313 _marking_context->mark_complete();
314
315 _free_set->rebuild();
316 }
317
318 if (ShenandoahAlwaysPreTouch) {
319 assert(!AlwaysPreTouch, "Should have been overridden");
320
321 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
322 // before initialize() below zeroes it with initializing thread. For any given region,
323 // we touch the region and the corresponding bitmaps from the same thread.
324 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
325
326 size_t pretouch_heap_page_size = heap_page_size;
327 size_t pretouch_bitmap_page_size = bitmap_page_size;
328
329 #ifdef LINUX
330 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
331 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
332 // them into huge one. Therefore, we need to pretouch with smaller pages.
333 if (UseTransparentHugePages) {
334 pretouch_heap_page_size = (size_t)os::vm_page_size();
335 pretouch_bitmap_page_size = (size_t)os::vm_page_size();
336 }
337 #endif
338
339 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
340 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
341
342 log_info(gc, init)("Pretouch bitmap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
343 _num_regions, pretouch_bitmap_page_size);
344 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, pretouch_bitmap_page_size);
345 _workers->run_task(&bcl);
346
347 log_info(gc, init)("Pretouch heap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
348 _num_regions, pretouch_heap_page_size);
349 ShenandoahPretouchHeapTask hcl(pretouch_heap_page_size);
350 _workers->run_task(&hcl);
351 }
352
353 //
354 // Initialize the rest of GC subsystems
355 //
356
357 _liveness_cache = NEW_C_HEAP_ARRAY(jushort*, _max_workers, mtGC);
358 for (uint worker = 0; worker < _max_workers; worker++) {
359 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(jushort, _num_regions, mtGC);
360 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(jushort));
361 }
362
363 // There should probably be Shenandoah-specific options for these,
364 // just as there are G1-specific options.
365 {
366 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
367 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
368 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
369 }
370
371 _monitoring_support = new ShenandoahMonitoringSupport(this);
372 _phase_timings = new ShenandoahPhaseTimings();
373 ShenandoahStringDedup::initialize();
374 ShenandoahCodeRoots::initialize();
375
376 if (ShenandoahPacing) {
377 _pacer = new ShenandoahPacer(this);
378 _pacer->setup_for_idle();
379 } else {
380 _pacer = NULL;
381 }
382
383 _control_thread = new ShenandoahControlThread();
384
385 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max",
386 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size),
387 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size),
388 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity())
389 );
390
391 log_info(gc, init)("Safepointing mechanism: thread-local poll");
392
393 return JNI_OK;
394 }
395
396 void ShenandoahHeap::initialize_heuristics() {
397 if (ShenandoahGCMode != NULL) {
398 if (strcmp(ShenandoahGCMode, "normal") == 0) {
399 _gc_mode = new ShenandoahNormalMode();
400 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
401 _gc_mode = new ShenandoahPassiveMode();
402 } else {
403 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
404 }
405 } else {
406 ShouldNotReachHere();
407 }
408 _gc_mode->initialize_flags();
409 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
410 vm_exit_during_initialization(
411 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
412 _gc_mode->name()));
413 }
414 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
415 vm_exit_during_initialization(
416 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
417 _gc_mode->name()));
418 }
419 log_info(gc, init)("Shenandoah GC mode: %s",
420 _gc_mode->name());
421
422 _heuristics = _gc_mode->initialize_heuristics();
423
424 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
425 vm_exit_during_initialization(
426 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
427 _heuristics->name()));
428 }
429 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
430 vm_exit_during_initialization(
431 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
432 _heuristics->name()));
433 }
434 log_info(gc, init)("Shenandoah heuristics: %s",
435 _heuristics->name());
436 }
437
438 #ifdef _MSC_VER
439 #pragma warning( push )
440 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
441 #endif
442
443 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
444 CollectedHeap(),
445 _initial_size(0),
446 _used(0),
447 _committed(0),
448 _bytes_allocated_since_gc_start(0),
449 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
450 _workers(NULL),
451 _safepoint_workers(NULL),
452 _heap_region_special(false),
453 _num_regions(0),
454 _regions(NULL),
455 _update_refs_iterator(this),
456 _control_thread(NULL),
457 _shenandoah_policy(policy),
458 _heuristics(NULL),
459 _free_set(NULL),
460 _scm(new ShenandoahConcurrentMark()),
461 _full_gc(new ShenandoahMarkCompact()),
462 _pacer(NULL),
463 _verifier(NULL),
464 _phase_timings(NULL),
465 _monitoring_support(NULL),
466 _memory_pool(NULL),
467 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
468 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
469 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
470 _soft_ref_policy(),
471 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
472 _ref_processor(NULL),
473 _marking_context(NULL),
474 _bitmap_size(0),
475 _bitmap_regions_per_slice(0),
476 _bitmap_bytes_per_slice(0),
477 _bitmap_region_special(false),
478 _aux_bitmap_region_special(false),
479 _liveness_cache(NULL),
480 _collection_set(NULL)
481 {
482 _heap = this;
483
484 log_info(gc, init)("GC threads: " UINT32_FORMAT " parallel, " UINT32_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
485 log_info(gc, init)("Reference processing: %s", ParallelRefProcEnabled ? "parallel" : "serial");
486
487 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
488
489 _max_workers = MAX2(_max_workers, 1U);
490 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
491 /* are_GC_task_threads */ true,
492 /* are_ConcurrentGC_threads */ true);
493 if (_workers == NULL) {
494 vm_exit_during_initialization("Failed necessary allocation.");
495 } else {
496 _workers->initialize_workers();
497 }
498
499 if (ParallelGCThreads > 1) {
500 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
501 ParallelGCThreads,
502 /* are_GC_task_threads */ false,
503 /* are_ConcurrentGC_threads */ false);
504 _safepoint_workers->initialize_workers();
505 }
506 }
507
508 #ifdef _MSC_VER
509 #pragma warning( pop )
510 #endif
511
512 class ShenandoahResetBitmapTask : public AbstractGangTask {
513 private:
514 ShenandoahRegionIterator _regions;
515
516 public:
517 ShenandoahResetBitmapTask() :
518 AbstractGangTask("Parallel Reset Bitmap Task") {}
519
520 void work(uint worker_id) {
521 ShenandoahHeapRegion* region = _regions.next();
522 ShenandoahHeap* heap = ShenandoahHeap::heap();
523 ShenandoahMarkingContext* const ctx = heap->marking_context();
524 while (region != NULL) {
525 if (heap->is_bitmap_slice_committed(region)) {
526 ctx->clear_bitmap(region);
527 }
528 region = _regions.next();
529 }
530 }
531 };
532
533 void ShenandoahHeap::reset_mark_bitmap() {
534 assert_gc_workers(_workers->active_workers());
535 mark_incomplete_marking_context();
536
537 ShenandoahResetBitmapTask task;
538 _workers->run_task(&task);
539 }
540
541 void ShenandoahHeap::print_on(outputStream* st) const {
542 st->print_cr("Shenandoah Heap");
543 st->print_cr(" " SIZE_FORMAT "%s total, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
544 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
545 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
546 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
547 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
548 num_regions(),
549 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
550 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
551
552 st->print("Status: ");
553 if (has_forwarded_objects()) st->print("has forwarded objects, ");
554 if (is_concurrent_mark_in_progress()) st->print("marking, ");
555 if (is_evacuation_in_progress()) st->print("evacuating, ");
556 if (is_update_refs_in_progress()) st->print("updating refs, ");
557 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
558 if (is_full_gc_in_progress()) st->print("full gc, ");
559 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
560 if (is_concurrent_root_in_progress()) st->print("concurrent roots, ");
561
562 if (cancelled_gc()) {
563 st->print("cancelled");
564 } else {
565 st->print("not cancelled");
566 }
567 st->cr();
568
569 st->print_cr("Reserved region:");
570 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
571 p2i(reserved_region().start()),
572 p2i(reserved_region().end()));
573
574 ShenandoahCollectionSet* cset = collection_set();
575 st->print_cr("Collection set:");
576 if (cset != NULL) {
577 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
578 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
579 } else {
580 st->print_cr(" (NULL)");
581 }
582
583 st->cr();
584 MetaspaceUtils::print_on(st);
585
586 if (Verbose) {
587 print_heap_regions_on(st);
588 }
589 }
590
591 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
592 public:
593 void do_thread(Thread* thread) {
594 assert(thread != NULL, "Sanity");
595 assert(thread->is_Worker_thread(), "Only worker thread expected");
596 ShenandoahThreadLocalData::initialize_gclab(thread);
597 }
598 };
599
600 void ShenandoahHeap::post_initialize() {
601 CollectedHeap::post_initialize();
602 MutexLocker ml(Threads_lock);
603
604 ShenandoahInitWorkerGCLABClosure init_gclabs;
605 _workers->threads_do(&init_gclabs);
606
607 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
608 // Now, we will let WorkGang to initialize gclab when new worker is created.
609 _workers->set_initialize_gclab();
610
611 _scm->initialize(_max_workers);
612 _full_gc->initialize(_gc_timer);
613
614 ref_processing_init();
615
616 _heuristics->initialize();
617
618 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
619 }
620
621 size_t ShenandoahHeap::used() const {
622 return Atomic::load_acquire(&_used);
623 }
624
625 size_t ShenandoahHeap::committed() const {
626 OrderAccess::acquire();
627 return _committed;
628 }
629
630 void ShenandoahHeap::increase_committed(size_t bytes) {
631 shenandoah_assert_heaplocked_or_safepoint();
632 _committed += bytes;
633 }
634
635 void ShenandoahHeap::decrease_committed(size_t bytes) {
636 shenandoah_assert_heaplocked_or_safepoint();
637 _committed -= bytes;
638 }
639
640 void ShenandoahHeap::increase_used(size_t bytes) {
641 Atomic::add(&_used, bytes);
642 }
643
644 void ShenandoahHeap::set_used(size_t bytes) {
645 Atomic::release_store_fence(&_used, bytes);
646 }
647
648 void ShenandoahHeap::decrease_used(size_t bytes) {
649 assert(used() >= bytes, "never decrease heap size by more than we've left");
650 Atomic::sub(&_used, bytes);
651 }
652
653 void ShenandoahHeap::increase_allocated(size_t bytes) {
654 Atomic::add(&_bytes_allocated_since_gc_start, bytes);
655 }
656
657 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
658 size_t bytes = words * HeapWordSize;
659 if (!waste) {
660 increase_used(bytes);
661 }
662 increase_allocated(bytes);
663 if (ShenandoahPacing) {
664 control_thread()->pacing_notify_alloc(words);
665 if (waste) {
666 pacer()->claim_for_alloc(words, true);
667 }
668 }
669 }
670
671 size_t ShenandoahHeap::capacity() const {
672 return committed();
673 }
674
675 size_t ShenandoahHeap::max_capacity() const {
676 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
677 }
678
679 size_t ShenandoahHeap::min_capacity() const {
680 return _minimum_size;
681 }
682
683 size_t ShenandoahHeap::initial_capacity() const {
684 return _initial_size;
685 }
686
687 bool ShenandoahHeap::is_in(const void* p) const {
688 HeapWord* heap_base = (HeapWord*) base();
689 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
690 return p >= heap_base && p < last_region_end;
691 }
692
693 void ShenandoahHeap::op_uncommit(double shrink_before) {
694 assert (ShenandoahUncommit, "should be enabled");
695
696 // Application allocates from the beginning of the heap, and GC allocates at
697 // the end of it. It is more efficient to uncommit from the end, so that applications
698 // could enjoy the near committed regions. GC allocations are much less frequent,
699 // and therefore can accept the committing costs.
700
701 size_t count = 0;
702 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
703 ShenandoahHeapRegion* r = get_region(i - 1);
704 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
705 ShenandoahHeapLocker locker(lock());
706 if (r->is_empty_committed()) {
707 // Do not uncommit below minimal capacity
708 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
709 break;
710 }
711
712 r->make_uncommitted();
713 count++;
714 }
715 }
716 SpinPause(); // allow allocators to take the lock
717 }
718
719 if (count > 0) {
720 control_thread()->notify_heap_changed();
721 }
722 }
723
724 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
725 // New object should fit the GCLAB size
726 size_t min_size = MAX2(size, PLAB::min_size());
727
728 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
729 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
730 new_size = MIN2(new_size, PLAB::max_size());
731 new_size = MAX2(new_size, PLAB::min_size());
732
733 // Record new heuristic value even if we take any shortcut. This captures
734 // the case when moderately-sized objects always take a shortcut. At some point,
735 // heuristics should catch up with them.
736 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
737
738 if (new_size < size) {
739 // New size still does not fit the object. Fall back to shared allocation.
740 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
741 return NULL;
742 }
743
744 // Retire current GCLAB, and allocate a new one.
745 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
746 gclab->retire();
747
748 size_t actual_size = 0;
749 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
750 if (gclab_buf == NULL) {
751 return NULL;
752 }
753
754 assert (size <= actual_size, "allocation should fit");
755
756 if (ZeroTLAB) {
757 // ..and clear it.
758 Copy::zero_to_words(gclab_buf, actual_size);
759 } else {
760 // ...and zap just allocated object.
761 #ifdef ASSERT
762 // Skip mangling the space corresponding to the object header to
763 // ensure that the returned space is not considered parsable by
764 // any concurrent GC thread.
765 size_t hdr_size = oopDesc::header_size();
766 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
767 #endif // ASSERT
768 }
769 gclab->set_buf(gclab_buf, actual_size);
770 return gclab->allocate(size);
771 }
772
773 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
774 size_t requested_size,
775 size_t* actual_size) {
776 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
777 HeapWord* res = allocate_memory(req);
778 if (res != NULL) {
779 *actual_size = req.actual_size();
780 } else {
781 *actual_size = 0;
782 }
783 return res;
784 }
785
786 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
787 size_t word_size,
788 size_t* actual_size) {
789 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
790 HeapWord* res = allocate_memory(req);
791 if (res != NULL) {
792 *actual_size = req.actual_size();
793 } else {
794 *actual_size = 0;
795 }
796 return res;
797 }
798
799 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
800 intptr_t pacer_epoch = 0;
801 bool in_new_region = false;
802 HeapWord* result = NULL;
803
804 if (req.is_mutator_alloc()) {
805 if (ShenandoahPacing) {
806 pacer()->pace_for_alloc(req.size());
807 pacer_epoch = pacer()->epoch();
808 }
809
810 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
811 result = allocate_memory_under_lock(req, in_new_region);
812 }
813
814 // Allocation failed, block until control thread reacted, then retry allocation.
815 //
816 // It might happen that one of the threads requesting allocation would unblock
817 // way later after GC happened, only to fail the second allocation, because
818 // other threads have already depleted the free storage. In this case, a better
819 // strategy is to try again, as long as GC makes progress.
820 //
821 // Then, we need to make sure the allocation was retried after at least one
822 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
823
824 size_t tries = 0;
825
826 while (result == NULL && _progress_last_gc.is_set()) {
827 tries++;
828 control_thread()->handle_alloc_failure(req);
829 result = allocate_memory_under_lock(req, in_new_region);
830 }
831
832 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
833 tries++;
834 control_thread()->handle_alloc_failure(req);
835 result = allocate_memory_under_lock(req, in_new_region);
836 }
837
838 } else {
839 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
840 result = allocate_memory_under_lock(req, in_new_region);
841 // Do not call handle_alloc_failure() here, because we cannot block.
842 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
843 }
844
845 if (in_new_region) {
846 control_thread()->notify_heap_changed();
847 }
848
849 if (result != NULL) {
850 size_t requested = req.size();
851 size_t actual = req.actual_size();
852
853 assert (req.is_lab_alloc() || (requested == actual),
854 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
855 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
856
857 if (req.is_mutator_alloc()) {
858 notify_mutator_alloc_words(actual, false);
859
860 // If we requested more than we were granted, give the rest back to pacer.
861 // This only matters if we are in the same pacing epoch: do not try to unpace
862 // over the budget for the other phase.
863 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
864 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
865 }
866 } else {
867 increase_used(actual*HeapWordSize);
868 }
869 }
870
871 return result;
872 }
873
874 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
875 ShenandoahHeapLocker locker(lock());
876 return _free_set->allocate(req, in_new_region);
877 }
878
879 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
880 bool* gc_overhead_limit_was_exceeded) {
881 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
882 return allocate_memory(req);
883 }
884
885 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
886 size_t size,
887 Metaspace::MetadataType mdtype) {
888 MetaWord* result;
889
890 // Inform metaspace OOM to GC heuristics if class unloading is possible.
891 if (heuristics()->can_unload_classes()) {
892 ShenandoahHeuristics* h = heuristics();
893 h->record_metaspace_oom();
894 }
895
896 // Expand and retry allocation
897 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
898 if (result != NULL) {
899 return result;
900 }
901
902 // Start full GC
903 collect(GCCause::_metadata_GC_clear_soft_refs);
904
905 // Retry allocation
906 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
907 if (result != NULL) {
908 return result;
909 }
910
911 // Expand and retry allocation
912 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
913 if (result != NULL) {
914 return result;
915 }
916
917 // Out of memory
918 return NULL;
919 }
920
921 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
922 private:
923 ShenandoahHeap* const _heap;
924 Thread* const _thread;
925 public:
926 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
927 _heap(heap), _thread(Thread::current()) {}
928
929 void do_object(oop p) {
930 shenandoah_assert_marked(NULL, p);
931 if (!p->is_forwarded()) {
932 _heap->evacuate_object(p, _thread);
933 }
934 }
935 };
936
937 class ShenandoahEvacuationTask : public AbstractGangTask {
938 private:
939 ShenandoahHeap* const _sh;
940 ShenandoahCollectionSet* const _cs;
941 bool _concurrent;
942 public:
943 ShenandoahEvacuationTask(ShenandoahHeap* sh,
944 ShenandoahCollectionSet* cs,
945 bool concurrent) :
946 AbstractGangTask("Parallel Evacuation Task"),
947 _sh(sh),
948 _cs(cs),
949 _concurrent(concurrent)
950 {}
951
952 void work(uint worker_id) {
953 if (_concurrent) {
954 ShenandoahConcurrentWorkerSession worker_session(worker_id);
955 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
956 ShenandoahEvacOOMScope oom_evac_scope;
957 do_work();
958 } else {
959 ShenandoahParallelWorkerSession worker_session(worker_id);
960 ShenandoahEvacOOMScope oom_evac_scope;
961 do_work();
962 }
963 }
964
965 private:
966 void do_work() {
967 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
968 ShenandoahHeapRegion* r;
969 while ((r =_cs->claim_next()) != NULL) {
970 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
971 _sh->marked_object_iterate(r, &cl);
972
973 if (ShenandoahPacing) {
974 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
975 }
976
977 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
978 break;
979 }
980 }
981 }
982 };
983
984 void ShenandoahHeap::trash_cset_regions() {
985 ShenandoahHeapLocker locker(lock());
986
987 ShenandoahCollectionSet* set = collection_set();
988 ShenandoahHeapRegion* r;
989 set->clear_current_index();
990 while ((r = set->next()) != NULL) {
991 r->make_trash();
992 }
993 collection_set()->clear();
994 }
995
996 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
997 st->print_cr("Heap Regions:");
998 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
999 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
1000 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark");
1001 st->print_cr("SN=alloc sequence number");
1002
1003 for (size_t i = 0; i < num_regions(); i++) {
1004 get_region(i)->print_on(st);
1005 }
1006 }
1007
1008 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1009 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1010
1011 oop humongous_obj = oop(start->bottom());
1012 size_t size = humongous_obj->size();
1013 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1014 size_t index = start->index() + required_regions - 1;
1015
1016 assert(!start->has_live(), "liveness must be zero");
1017
1018 for(size_t i = 0; i < required_regions; i++) {
1019 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1020 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1021 ShenandoahHeapRegion* region = get_region(index --);
1022
1023 assert(region->is_humongous(), "expect correct humongous start or continuation");
1024 assert(!region->is_cset(), "Humongous region should not be in collection set");
1025
1026 region->make_trash_immediate();
1027 }
1028 }
1029
1030 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1031 public:
1032 void do_thread(Thread* thread) {
1033 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1034 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1035 gclab->retire();
1036 }
1037 };
1038
1039 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
1040 if (UseTLAB) {
1041 CollectedHeap::ensure_parsability(retire_tlabs);
1042 }
1043 ShenandoahRetireGCLABClosure cl;
1044 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1045 cl.do_thread(t);
1046 }
1047 workers()->threads_do(&cl);
1048 }
1049
1050 void ShenandoahHeap::resize_tlabs() {
1051 CollectedHeap::resize_all_tlabs();
1052 }
1053
1054 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1055 private:
1056 ShenandoahRootEvacuator* _rp;
1057
1058 public:
1059 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1060 AbstractGangTask("Shenandoah evacuate and update roots"),
1061 _rp(rp) {}
1062
1063 void work(uint worker_id) {
1064 ShenandoahParallelWorkerSession worker_session(worker_id);
1065 ShenandoahEvacOOMScope oom_evac_scope;
1066 ShenandoahEvacuateUpdateRootsClosure<> cl;
1067 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1068 _rp->roots_do(worker_id, &cl);
1069 }
1070 };
1071
1072 void ShenandoahHeap::evacuate_and_update_roots() {
1073 #if COMPILER2_OR_JVMCI
1074 DerivedPointerTable::clear();
1075 #endif
1076 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1077 {
1078 // Include concurrent roots if current cycle can not process those roots concurrently
1079 ShenandoahRootEvacuator rp(workers()->active_workers(),
1080 ShenandoahPhaseTimings::init_evac,
1081 !ShenandoahConcurrentRoots::should_do_concurrent_roots(),
1082 !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
1083 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1084 workers()->run_task(&roots_task);
1085 }
1086
1087 #if COMPILER2_OR_JVMCI
1088 DerivedPointerTable::update_pointers();
1089 #endif
1090 }
1091
1092 // Returns size in bytes
1093 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1094 if (ShenandoahElasticTLAB) {
1095 // With Elastic TLABs, return the max allowed size, and let the allocation path
1096 // figure out the safe size for current allocation.
1097 return ShenandoahHeapRegion::max_tlab_size_bytes();
1098 } else {
1099 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1100 }
1101 }
1102
1103 size_t ShenandoahHeap::max_tlab_size() const {
1104 // Returns size in words
1105 return ShenandoahHeapRegion::max_tlab_size_words();
1106 }
1107
1108 class ShenandoahRetireAndResetGCLABClosure : public ThreadClosure {
1109 public:
1110 void do_thread(Thread* thread) {
1111 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1112 gclab->retire();
1113 if (ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1114 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1115 }
1116 }
1117 };
1118
1119 void ShenandoahHeap::retire_and_reset_gclabs() {
1120 ShenandoahRetireAndResetGCLABClosure cl;
1121 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1122 cl.do_thread(t);
1123 }
1124 workers()->threads_do(&cl);
1125 }
1126
1127 void ShenandoahHeap::collect(GCCause::Cause cause) {
1128 control_thread()->request_gc(cause);
1129 }
1130
1131 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1132 //assert(false, "Shouldn't need to do full collections");
1133 }
1134
1135 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1136 ShenandoahHeapRegion* r = heap_region_containing(addr);
1137 if (r != NULL) {
1138 return r->block_start(addr);
1139 }
1140 return NULL;
1141 }
1142
1143 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1144 ShenandoahHeapRegion* r = heap_region_containing(addr);
1145 return r->block_is_obj(addr);
1146 }
1147
1148 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1149 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1150 }
1151
1152 jlong ShenandoahHeap::millis_since_last_gc() {
1153 double v = heuristics()->time_since_last_gc() * 1000;
1154 assert(0 <= v && v <= max_jlong, "value should fit: %f", v);
1155 return (jlong)v;
1156 }
1157
1158 void ShenandoahHeap::prepare_for_verify() {
1159 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1160 make_parsable(false);
1161 }
1162 }
1163
1164 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1165 workers()->print_worker_threads_on(st);
1166 if (ShenandoahStringDedup::is_enabled()) {
1167 ShenandoahStringDedup::print_worker_threads_on(st);
1168 }
1169 }
1170
1171 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1172 workers()->threads_do(tcl);
1173 if (_safepoint_workers != NULL) {
1174 _safepoint_workers->threads_do(tcl);
1175 }
1176 if (ShenandoahStringDedup::is_enabled()) {
1177 ShenandoahStringDedup::threads_do(tcl);
1178 }
1179 }
1180
1181 void ShenandoahHeap::print_tracing_info() const {
1182 LogTarget(Info, gc, stats) lt;
1183 if (lt.is_enabled()) {
1184 ResourceMark rm;
1185 LogStream ls(lt);
1186
1187 phase_timings()->print_on(&ls);
1188
1189 ls.cr();
1190 ls.cr();
1191
1192 shenandoah_policy()->print_gc_stats(&ls);
1193
1194 ls.cr();
1195 ls.cr();
1196
1197 if (ShenandoahPacing) {
1198 pacer()->print_on(&ls);
1199 }
1200
1201 ls.cr();
1202 ls.cr();
1203 }
1204 }
1205
1206 void ShenandoahHeap::verify(VerifyOption vo) {
1207 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1208 if (ShenandoahVerify) {
1209 verifier()->verify_generic(vo);
1210 } else {
1211 // TODO: Consider allocating verification bitmaps on demand,
1212 // and turn this on unconditionally.
1213 }
1214 }
1215 }
1216 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1217 return _free_set->capacity();
1218 }
1219
1220 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1221 private:
1222 MarkBitMap* _bitmap;
1223 Stack<oop,mtGC>* _oop_stack;
1224 ShenandoahHeap* const _heap;
1225 ShenandoahMarkingContext* const _marking_context;
1226
1227 template <class T>
1228 void do_oop_work(T* p) {
1229 T o = RawAccess<>::oop_load(p);
1230 if (!CompressedOops::is_null(o)) {
1231 oop obj = CompressedOops::decode_not_null(o);
1232 if (_heap->is_concurrent_root_in_progress() && !_marking_context->is_marked(obj)) {
1233 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1234 return;
1235 }
1236 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1237
1238 assert(oopDesc::is_oop(obj), "must be a valid oop");
1239 if (!_bitmap->is_marked(obj)) {
1240 _bitmap->mark(obj);
1241 _oop_stack->push(obj);
1242 }
1243 }
1244 }
1245 public:
1246 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1247 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1248 _marking_context(_heap->marking_context()) {}
1249 void do_oop(oop* p) { do_oop_work(p); }
1250 void do_oop(narrowOop* p) { do_oop_work(p); }
1251 };
1252
1253 /*
1254 * This is public API, used in preparation of object_iterate().
1255 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1256 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1257 * control, we call SH::make_tlabs_parsable().
1258 */
1259 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1260 // No-op.
1261 }
1262
1263 /*
1264 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1265 *
1266 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1267 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1268 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1269 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1270 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1271 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1272 * wiped the bitmap in preparation for next marking).
1273 *
1274 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1275 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1276 * is allowed to report dead objects, but is not required to do so.
1277 */
1278 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1279 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1280 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1281 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1282 return;
1283 }
1284
1285 // Reset bitmap
1286 _aux_bit_map.clear();
1287
1288 Stack<oop,mtGC> oop_stack;
1289
1290 // First, we process GC roots according to current GC cycle. This populates the work stack with initial objects.
1291 ShenandoahHeapIterationRootScanner rp;
1292 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1293
1294 rp.roots_do(&oops);
1295
1296 // Work through the oop stack to traverse heap.
1297 while (! oop_stack.is_empty()) {
1298 oop obj = oop_stack.pop();
1299 assert(oopDesc::is_oop(obj), "must be a valid oop");
1300 cl->do_object(obj);
1301 obj->oop_iterate(&oops);
1302 }
1303
1304 assert(oop_stack.is_empty(), "should be empty");
1305
1306 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1307 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1308 }
1309 }
1310
1311 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1312 void ShenandoahHeap::keep_alive(oop obj) {
1313 if (is_concurrent_mark_in_progress()) {
1314 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1315 }
1316 }
1317
1318 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1319 for (size_t i = 0; i < num_regions(); i++) {
1320 ShenandoahHeapRegion* current = get_region(i);
1321 blk->heap_region_do(current);
1322 }
1323 }
1324
1325 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1326 private:
1327 ShenandoahHeap* const _heap;
1328 ShenandoahHeapRegionClosure* const _blk;
1329
1330 shenandoah_padding(0);
1331 volatile size_t _index;
1332 shenandoah_padding(1);
1333
1334 public:
1335 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1336 AbstractGangTask("Parallel Region Task"),
1337 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1338
1339 void work(uint worker_id) {
1340 size_t stride = ShenandoahParallelRegionStride;
1341
1342 size_t max = _heap->num_regions();
1343 while (_index < max) {
1344 size_t cur = Atomic::fetch_and_add(&_index, stride);
1345 size_t start = cur;
1346 size_t end = MIN2(cur + stride, max);
1347 if (start >= max) break;
1348
1349 for (size_t i = cur; i < end; i++) {
1350 ShenandoahHeapRegion* current = _heap->get_region(i);
1351 _blk->heap_region_do(current);
1352 }
1353 }
1354 }
1355 };
1356
1357 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1358 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1359 if (num_regions() > ShenandoahParallelRegionStride) {
1360 ShenandoahParallelHeapRegionTask task(blk);
1361 workers()->run_task(&task);
1362 } else {
1363 heap_region_iterate(blk);
1364 }
1365 }
1366
1367 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1368 private:
1369 ShenandoahMarkingContext* const _ctx;
1370 public:
1371 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1372
1373 void heap_region_do(ShenandoahHeapRegion* r) {
1374 if (r->is_active()) {
1375 r->clear_live_data();
1376 _ctx->capture_top_at_mark_start(r);
1377 } else {
1378 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1379 assert(_ctx->top_at_mark_start(r) == r->top(),
1380 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1381 }
1382 }
1383
1384 bool is_thread_safe() { return true; }
1385 };
1386
1387 void ShenandoahHeap::op_init_mark() {
1388 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1389 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1390
1391 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1392 assert(!marking_context()->is_complete(), "should not be complete");
1393 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1394
1395 if (ShenandoahVerify) {
1396 verifier()->verify_before_concmark();
1397 }
1398
1399 if (VerifyBeforeGC) {
1400 Universe::verify();
1401 }
1402
1403 set_concurrent_mark_in_progress(true);
1404 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1405 {
1406 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1407 make_parsable(true);
1408 }
1409
1410 {
1411 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_region_states);
1412 ShenandoahInitMarkUpdateRegionStateClosure cl;
1413 parallel_heap_region_iterate(&cl);
1414 }
1415
1416 // Make above changes visible to worker threads
1417 OrderAccess::fence();
1418
1419 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1420
1421 if (UseTLAB) {
1422 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1423 resize_tlabs();
1424 }
1425
1426 if (ShenandoahPacing) {
1427 pacer()->setup_for_mark();
1428 }
1429
1430 // Arm nmethods for concurrent marking. When a nmethod is about to be executed,
1431 // we need to make sure that all its metadata are marked. alternative is to remark
1432 // thread roots at final mark pause, but it can be potential latency killer.
1433 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1434 ShenandoahCodeRoots::arm_nmethods();
1435 }
1436 }
1437
1438 void ShenandoahHeap::op_mark() {
1439 concurrent_mark()->mark_from_roots();
1440 }
1441
1442 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1443 private:
1444 ShenandoahMarkingContext* const _ctx;
1445 ShenandoahHeapLock* const _lock;
1446
1447 public:
1448 ShenandoahFinalMarkUpdateRegionStateClosure() :
1449 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1450
1451 void heap_region_do(ShenandoahHeapRegion* r) {
1452 if (r->is_active()) {
1453 // All allocations past TAMS are implicitly live, adjust the region data.
1454 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1455 HeapWord *tams = _ctx->top_at_mark_start(r);
1456 HeapWord *top = r->top();
1457 if (top > tams) {
1458 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1459 }
1460
1461 // We are about to select the collection set, make sure it knows about
1462 // current pinning status. Also, this allows trashing more regions that
1463 // now have their pinning status dropped.
1464 if (r->is_pinned()) {
1465 if (r->pin_count() == 0) {
1466 ShenandoahHeapLocker locker(_lock);
1467 r->make_unpinned();
1468 }
1469 } else {
1470 if (r->pin_count() > 0) {
1471 ShenandoahHeapLocker locker(_lock);
1472 r->make_pinned();
1473 }
1474 }
1475
1476 // Remember limit for updating refs. It's guaranteed that we get no
1477 // from-space-refs written from here on.
1478 r->set_update_watermark(r->top());
1479 } else {
1480 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1481 assert(_ctx->top_at_mark_start(r) == r->top(),
1482 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1483 }
1484 }
1485
1486 bool is_thread_safe() { return true; }
1487 };
1488
1489 void ShenandoahHeap::op_final_mark() {
1490 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1491 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1492
1493 // It is critical that we
1494 // evacuate roots right after finishing marking, so that we don't
1495 // get unmarked objects in the roots.
1496
1497 if (!cancelled_gc()) {
1498 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1499
1500 // Marking is completed, deactivate SATB barrier
1501 set_concurrent_mark_in_progress(false);
1502 mark_complete_marking_context();
1503
1504 parallel_cleaning(false /* full gc*/);
1505
1506 if (ShenandoahVerify) {
1507 verifier()->verify_roots_no_forwarded();
1508 }
1509
1510 {
1511 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_region_states);
1512 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1513 parallel_heap_region_iterate(&cl);
1514
1515 assert_pinned_region_status();
1516 }
1517
1518 // Force the threads to reacquire their TLABs outside the collection set.
1519 {
1520 ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs);
1521 make_parsable(true);
1522 }
1523
1524 {
1525 ShenandoahGCPhase phase(ShenandoahPhaseTimings::choose_cset);
1526 ShenandoahHeapLocker locker(lock());
1527 _collection_set->clear();
1528 heuristics()->choose_collection_set(_collection_set);
1529 }
1530
1531 {
1532 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_rebuild_freeset);
1533 ShenandoahHeapLocker locker(lock());
1534 _free_set->rebuild();
1535 }
1536
1537 if (!is_degenerated_gc_in_progress()) {
1538 prepare_concurrent_roots();
1539 prepare_concurrent_unloading();
1540 }
1541
1542 // If collection set has candidates, start evacuation.
1543 // Otherwise, bypass the rest of the cycle.
1544 if (!collection_set()->is_empty()) {
1545 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1546
1547 if (ShenandoahVerify) {
1548 verifier()->verify_before_evacuation();
1549 }
1550
1551 set_evacuation_in_progress(true);
1552 // From here on, we need to update references.
1553 set_has_forwarded_objects(true);
1554
1555 if (!is_degenerated_gc_in_progress()) {
1556 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1557 ShenandoahCodeRoots::arm_nmethods();
1558 }
1559 evacuate_and_update_roots();
1560 }
1561
1562 if (ShenandoahPacing) {
1563 pacer()->setup_for_evac();
1564 }
1565
1566 if (ShenandoahVerify) {
1567 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::None;
1568 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1569 types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots);
1570 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots);
1571 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::StringDedupRoots);
1572 }
1573
1574 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1575 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CodeRoots);
1576 }
1577 verifier()->verify_roots_no_forwarded_except(types);
1578 verifier()->verify_during_evacuation();
1579 }
1580 } else {
1581 if (ShenandoahVerify) {
1582 verifier()->verify_after_concmark();
1583 }
1584
1585 if (VerifyAfterGC) {
1586 Universe::verify();
1587 }
1588 }
1589
1590 } else {
1591 // If this cycle was updating references, we need to keep the has_forwarded_objects
1592 // flag on, for subsequent phases to deal with it.
1593 concurrent_mark()->cancel();
1594 set_concurrent_mark_in_progress(false);
1595
1596 if (process_references()) {
1597 // Abandon reference processing right away: pre-cleaning must have failed.
1598 ReferenceProcessor *rp = ref_processor();
1599 rp->disable_discovery();
1600 rp->abandon_partial_discovery();
1601 rp->verify_no_references_recorded();
1602 }
1603 }
1604 }
1605
1606 void ShenandoahHeap::op_conc_evac() {
1607 ShenandoahEvacuationTask task(this, _collection_set, true);
1608 workers()->run_task(&task);
1609 }
1610
1611 void ShenandoahHeap::op_stw_evac() {
1612 ShenandoahEvacuationTask task(this, _collection_set, false);
1613 workers()->run_task(&task);
1614 }
1615
1616 void ShenandoahHeap::op_updaterefs() {
1617 update_heap_references(true);
1618 }
1619
1620 void ShenandoahHeap::op_cleanup() {
1621 free_set()->recycle_trash();
1622 }
1623
1624 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask {
1625 private:
1626 ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
1627 ShenandoahWeakRoots<true /*concurrent*/> _weak_roots;
1628 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots;
1629 ShenandoahConcurrentStringDedupRoots _dedup_roots;
1630 bool _include_weak_roots;
1631
1632 public:
1633 ShenandoahConcurrentRootsEvacUpdateTask(bool include_weak_roots) :
1634 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Roots Task"),
1635 _include_weak_roots(include_weak_roots) {
1636 }
1637
1638 void work(uint worker_id) {
1639 ShenandoahEvacOOMScope oom;
1640 {
1641 // vm_roots and weak_roots are OopStorage backed roots, concurrent iteration
1642 // may race against OopStorage::release() calls.
1643 ShenandoahEvacUpdateOopStorageRootsClosure cl;
1644 _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1645
1646 if (_include_weak_roots) {
1647 _weak_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1648 }
1649 }
1650
1651 {
1652 ShenandoahEvacuateUpdateRootsClosure<> cl;
1653 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1654 _cld_roots.cld_do(&clds);
1655 }
1656
1657 {
1658 ShenandoahForwardedIsAliveClosure is_alive;
1659 ShenandoahEvacuateUpdateRootsClosure<MO_RELEASE> keep_alive;
1660 _dedup_roots.oops_do(&is_alive, &keep_alive, worker_id);
1661 }
1662 }
1663 };
1664
1665 class ShenandoahEvacUpdateCleanupOopStorageRootsClosure : public BasicOopIterateClosure {
1666 private:
1667 ShenandoahHeap* const _heap;
1668 ShenandoahMarkingContext* const _mark_context;
1669 bool _evac_in_progress;
1670 Thread* const _thread;
1671 size_t _dead_counter;
1672
1673 public:
1674 ShenandoahEvacUpdateCleanupOopStorageRootsClosure();
1675 void do_oop(oop* p);
1676 void do_oop(narrowOop* p);
1677
1678 size_t dead_counter() const;
1679 void reset_dead_counter();
1680 };
1681
1682 ShenandoahEvacUpdateCleanupOopStorageRootsClosure::ShenandoahEvacUpdateCleanupOopStorageRootsClosure() :
1683 _heap(ShenandoahHeap::heap()),
1684 _mark_context(ShenandoahHeap::heap()->marking_context()),
1685 _evac_in_progress(ShenandoahHeap::heap()->is_evacuation_in_progress()),
1686 _thread(Thread::current()),
1687 _dead_counter(0) {
1688 }
1689
1690 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(oop* p) {
1691 const oop obj = RawAccess<>::oop_load(p);
1692 if (!CompressedOops::is_null(obj)) {
1693 if (!_mark_context->is_marked(obj)) {
1694 shenandoah_assert_correct(p, obj);
1695 oop old = Atomic::cmpxchg(p, obj, oop(NULL));
1696 if (obj == old) {
1697 _dead_counter ++;
1698 }
1699 } else if (_evac_in_progress && _heap->in_collection_set(obj)) {
1700 oop resolved = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1701 if (resolved == obj) {
1702 resolved = _heap->evacuate_object(obj, _thread);
1703 }
1704 Atomic::cmpxchg(p, obj, resolved);
1705 assert(_heap->cancelled_gc() ||
1706 _mark_context->is_marked(resolved) && !_heap->in_collection_set(resolved),
1707 "Sanity");
1708 }
1709 }
1710 }
1711
1712 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(narrowOop* p) {
1713 ShouldNotReachHere();
1714 }
1715
1716 size_t ShenandoahEvacUpdateCleanupOopStorageRootsClosure::dead_counter() const {
1717 return _dead_counter;
1718 }
1719
1720 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::reset_dead_counter() {
1721 _dead_counter = 0;
1722 }
1723
1724 // This task not only evacuates/updates marked weak roots, but also "NULL"
1725 // dead weak roots.
1726 class ShenandoahConcurrentWeakRootsEvacUpdateTask : public AbstractGangTask {
1727 private:
1728 ShenandoahWeakRoot<true /*concurrent*/> _jni_roots;
1729 ShenandoahWeakRoot<true /*concurrent*/> _string_table_roots;
1730 ShenandoahWeakRoot<true /*concurrent*/> _resolved_method_table_roots;
1731 ShenandoahWeakRoot<true /*concurrent*/> _vm_roots;
1732
1733 public:
1734 ShenandoahConcurrentWeakRootsEvacUpdateTask() :
1735 AbstractGangTask("Shenandoah Concurrent Weak Root Task"),
1736 _jni_roots(OopStorageSet::jni_weak(), ShenandoahPhaseTimings::JNIWeakRoots),
1737 _string_table_roots(OopStorageSet::string_table_weak(), ShenandoahPhaseTimings::StringTableRoots),
1738 _resolved_method_table_roots(OopStorageSet::resolved_method_table_weak(), ShenandoahPhaseTimings::ResolvedMethodTableRoots),
1739 _vm_roots(OopStorageSet::vm_weak(), ShenandoahPhaseTimings::VMWeakRoots) {
1740 StringTable::reset_dead_counter();
1741 ResolvedMethodTable::reset_dead_counter();
1742 }
1743
1744 ~ShenandoahConcurrentWeakRootsEvacUpdateTask() {
1745 StringTable::finish_dead_counter();
1746 ResolvedMethodTable::finish_dead_counter();
1747 }
1748
1749 void work(uint worker_id) {
1750 ShenandoahEvacOOMScope oom;
1751 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
1752 // may race against OopStorage::release() calls.
1753 ShenandoahEvacUpdateCleanupOopStorageRootsClosure cl;
1754 _jni_roots.oops_do(&cl, worker_id);
1755 _vm_roots.oops_do(&cl, worker_id);
1756
1757 cl.reset_dead_counter();
1758 _string_table_roots.oops_do(&cl, worker_id);
1759 StringTable::inc_dead_counter(cl.dead_counter());
1760
1761 cl.reset_dead_counter();
1762 _resolved_method_table_roots.oops_do(&cl, worker_id);
1763 ResolvedMethodTable::inc_dead_counter(cl.dead_counter());
1764 }
1765 };
1766
1767 void ShenandoahHeap::op_roots() {
1768 if (is_concurrent_root_in_progress()) {
1769 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1770 // Concurrent weak root processing
1771 ShenandoahConcurrentWeakRootsEvacUpdateTask task;
1772 workers()->run_task(&task);
1773
1774 _unloader.unload();
1775 }
1776
1777 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1778 ShenandoahConcurrentRootsEvacUpdateTask task(!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
1779 workers()->run_task(&task);
1780 }
1781 }
1782
1783 set_concurrent_root_in_progress(false);
1784 }
1785
1786 void ShenandoahHeap::op_reset() {
1787 if (ShenandoahPacing) {
1788 pacer()->setup_for_reset();
1789 }
1790 reset_mark_bitmap();
1791 }
1792
1793 void ShenandoahHeap::op_preclean() {
1794 if (ShenandoahPacing) {
1795 pacer()->setup_for_preclean();
1796 }
1797 concurrent_mark()->preclean_weak_refs();
1798 }
1799
1800 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1801 ShenandoahMetricsSnapshot metrics;
1802 metrics.snap_before();
1803
1804 full_gc()->do_it(cause);
1805 if (UseTLAB) {
1806 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs);
1807 resize_all_tlabs();
1808 }
1809
1810 metrics.snap_after();
1811
1812 if (metrics.is_good_progress()) {
1813 _progress_last_gc.set();
1814 } else {
1815 // Nothing to do. Tell the allocation path that we have failed to make
1816 // progress, and it can finally fail.
1817 _progress_last_gc.unset();
1818 }
1819 }
1820
1821 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1822 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1823 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1824 // some phase, we have to upgrade the Degenerate GC to Full GC.
1825
1826 clear_cancelled_gc();
1827
1828 ShenandoahMetricsSnapshot metrics;
1829 metrics.snap_before();
1830
1831 switch (point) {
1832 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1833 // but enters it at different points, depending on which concurrent phase had
1834 // degenerated.
1835
1836 case _degenerated_outside_cycle:
1837 // We have degenerated from outside the cycle, which means something is bad with
1838 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1839 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1840 // we can do the most aggressive degen cycle, which includes processing references and
1841 // class unloading, unless those features are explicitly disabled.
1842 //
1843 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1844 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1845 set_process_references(heuristics()->can_process_references());
1846 set_unload_classes(heuristics()->can_unload_classes());
1847
1848 op_reset();
1849
1850 op_init_mark();
1851 if (cancelled_gc()) {
1852 op_degenerated_fail();
1853 return;
1854 }
1855
1856 case _degenerated_mark:
1857 op_final_mark();
1858 if (cancelled_gc()) {
1859 op_degenerated_fail();
1860 return;
1861 }
1862
1863 if (!has_forwarded_objects() && ShenandoahConcurrentRoots::can_do_concurrent_class_unloading()) {
1864 // Disarm nmethods that armed for concurrent mark. On normal cycle, it would
1865 // be disarmed while conc-roots phase is running.
1866 // TODO: Call op_conc_roots() here instead
1867 ShenandoahCodeRoots::disarm_nmethods();
1868 }
1869
1870 op_cleanup();
1871
1872 case _degenerated_evac:
1873 // If heuristics thinks we should do the cycle, this flag would be set,
1874 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
1875 if (is_evacuation_in_progress()) {
1876
1877 // Degeneration under oom-evac protocol might have left some objects in
1878 // collection set un-evacuated. Restart evacuation from the beginning to
1879 // capture all objects. For all the objects that are already evacuated,
1880 // it would be a simple check, which is supposed to be fast. This is also
1881 // safe to do even without degeneration, as CSet iterator is at beginning
1882 // in preparation for evacuation anyway.
1883 //
1884 // Before doing that, we need to make sure we never had any cset-pinned
1885 // regions. This may happen if allocation failure happened when evacuating
1886 // the about-to-be-pinned object, oom-evac protocol left the object in
1887 // the collection set, and then the pin reached the cset region. If we continue
1888 // the cycle here, we would trash the cset and alive objects in it. To avoid
1889 // it, we fail degeneration right away and slide into Full GC to recover.
1890
1891 {
1892 sync_pinned_region_status();
1893 collection_set()->clear_current_index();
1894
1895 ShenandoahHeapRegion* r;
1896 while ((r = collection_set()->next()) != NULL) {
1897 if (r->is_pinned()) {
1898 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1899 op_degenerated_fail();
1900 return;
1901 }
1902 }
1903
1904 collection_set()->clear_current_index();
1905 }
1906
1907 op_stw_evac();
1908 if (cancelled_gc()) {
1909 op_degenerated_fail();
1910 return;
1911 }
1912 }
1913
1914 // If heuristics thinks we should do the cycle, this flag would be set,
1915 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
1916 if (has_forwarded_objects()) {
1917 op_init_updaterefs();
1918 if (cancelled_gc()) {
1919 op_degenerated_fail();
1920 return;
1921 }
1922 }
1923
1924 case _degenerated_updaterefs:
1925 if (has_forwarded_objects()) {
1926 op_final_updaterefs();
1927 if (cancelled_gc()) {
1928 op_degenerated_fail();
1929 return;
1930 }
1931 }
1932
1933 op_cleanup();
1934 break;
1935
1936 default:
1937 ShouldNotReachHere();
1938 }
1939
1940 if (ShenandoahVerify) {
1941 verifier()->verify_after_degenerated();
1942 }
1943
1944 if (VerifyAfterGC) {
1945 Universe::verify();
1946 }
1947
1948 metrics.snap_after();
1949
1950 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
1951 // because that probably means the heap is overloaded and/or fragmented.
1952 if (!metrics.is_good_progress()) {
1953 _progress_last_gc.unset();
1954 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1955 op_degenerated_futile();
1956 } else {
1957 _progress_last_gc.set();
1958 }
1959 }
1960
1961 void ShenandoahHeap::op_degenerated_fail() {
1962 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
1963 shenandoah_policy()->record_degenerated_upgrade_to_full();
1964 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1965 }
1966
1967 void ShenandoahHeap::op_degenerated_futile() {
1968 shenandoah_policy()->record_degenerated_upgrade_to_full();
1969 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1970 }
1971
1972 void ShenandoahHeap::force_satb_flush_all_threads() {
1973 if (!is_concurrent_mark_in_progress()) {
1974 // No need to flush SATBs
1975 return;
1976 }
1977
1978 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1979 ShenandoahThreadLocalData::set_force_satb_flush(t, true);
1980 }
1981 // The threads are not "acquiring" their thread-local data, but it does not
1982 // hurt to "release" the updates here anyway.
1983 OrderAccess::fence();
1984 }
1985
1986 void ShenandoahHeap::set_gc_state_all_threads(char state) {
1987 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1988 ShenandoahThreadLocalData::set_gc_state(t, state);
1989 }
1990 }
1991
1992 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1993 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1994 _gc_state.set_cond(mask, value);
1995 set_gc_state_all_threads(_gc_state.raw_value());
1996 }
1997
1998 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1999 if (has_forwarded_objects()) {
2000 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
2001 } else {
2002 set_gc_state_mask(MARKING, in_progress);
2003 }
2004 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
2005 }
2006
2007 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
2008 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
2009 set_gc_state_mask(EVACUATION, in_progress);
2010 }
2011
2012 void ShenandoahHeap::set_concurrent_root_in_progress(bool in_progress) {
2013 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
2014 if (in_progress) {
2015 _concurrent_root_in_progress.set();
2016 } else {
2017 _concurrent_root_in_progress.unset();
2018 }
2019 }
2020
2021 void ShenandoahHeap::ref_processing_init() {
2022 assert(_max_workers > 0, "Sanity");
2023
2024 _ref_processor =
2025 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
2026 ParallelRefProcEnabled, // MT processing
2027 _max_workers, // Degree of MT processing
2028 true, // MT discovery
2029 _max_workers, // Degree of MT discovery
2030 false, // Reference discovery is not atomic
2031 NULL, // No closure, should be installed before use
2032 true); // Scale worker threads
2033
2034 shenandoah_assert_rp_isalive_not_installed();
2035 }
2036
2037 GCTracer* ShenandoahHeap::tracer() {
2038 return shenandoah_policy()->tracer();
2039 }
2040
2041 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
2042 return _free_set->used();
2043 }
2044
2045 bool ShenandoahHeap::try_cancel_gc() {
2046 while (true) {
2047 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
2048 if (prev == CANCELLABLE) return true;
2049 else if (prev == CANCELLED) return false;
2050 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
2051 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
2052 if (Thread::current()->is_Java_thread()) {
2053 // We need to provide a safepoint here, otherwise we might
2054 // spin forever if a SP is pending.
2055 ThreadBlockInVM sp(JavaThread::current());
2056 SpinPause();
2057 }
2058 }
2059 }
2060
2061 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
2062 if (try_cancel_gc()) {
2063 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
2064 log_info(gc)("%s", msg.buffer());
2065 Events::log(Thread::current(), "%s", msg.buffer());
2066 }
2067 }
2068
2069 uint ShenandoahHeap::max_workers() {
2070 return _max_workers;
2071 }
2072
2073 void ShenandoahHeap::stop() {
2074 // The shutdown sequence should be able to terminate when GC is running.
2075
2076 // Step 0. Notify policy to disable event recording.
2077 _shenandoah_policy->record_shutdown();
2078
2079 // Step 1. Notify control thread that we are in shutdown.
2080 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
2081 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
2082 control_thread()->prepare_for_graceful_shutdown();
2083
2084 // Step 2. Notify GC workers that we are cancelling GC.
2085 cancel_gc(GCCause::_shenandoah_stop_vm);
2086
2087 // Step 3. Wait until GC worker exits normally.
2088 control_thread()->stop();
2089
2090 // Step 4. Stop String Dedup thread if it is active
2091 if (ShenandoahStringDedup::is_enabled()) {
2092 ShenandoahStringDedup::stop();
2093 }
2094 }
2095
2096 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
2097 if (!unload_classes()) return;
2098 bool purged_class;
2099
2100 // Unload classes and purge SystemDictionary.
2101 {
2102 ShenandoahGCPhase phase(full_gc ?
2103 ShenandoahPhaseTimings::full_gc_purge_class_unload :
2104 ShenandoahPhaseTimings::purge_class_unload);
2105 purged_class = SystemDictionary::do_unloading(gc_timer());
2106 }
2107
2108 {
2109 ShenandoahGCPhase phase(full_gc ?
2110 ShenandoahPhaseTimings::full_gc_purge_par :
2111 ShenandoahPhaseTimings::purge_par);
2112 ShenandoahIsAliveSelector is_alive;
2113 uint num_workers = _workers->active_workers();
2114 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
2115 _workers->run_task(&unlink_task);
2116 }
2117
2118 {
2119 ShenandoahGCPhase phase(full_gc ?
2120 ShenandoahPhaseTimings::full_gc_purge_cldg :
2121 ShenandoahPhaseTimings::purge_cldg);
2122 ClassLoaderDataGraph::purge();
2123 }
2124 // Resize and verify metaspace
2125 MetaspaceGC::compute_new_size();
2126 MetaspaceUtils::verify_metrics();
2127 }
2128
2129 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
2130 // so they should not have forwarded oops.
2131 // However, we do need to "null" dead oops in the roots, if can not be done
2132 // in concurrent cycles.
2133 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
2134 ShenandoahGCPhase root_phase(full_gc ?
2135 ShenandoahPhaseTimings::full_gc_purge :
2136 ShenandoahPhaseTimings::purge);
2137 uint num_workers = _workers->active_workers();
2138 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
2139 ShenandoahPhaseTimings::full_gc_purge_par :
2140 ShenandoahPhaseTimings::purge_par;
2141 ShenandoahGCPhase phase(timing_phase);
2142 ShenandoahGCWorkerPhase worker_phase(timing_phase);
2143
2144 // Cleanup weak roots
2145 if (has_forwarded_objects()) {
2146 ShenandoahForwardedIsAliveClosure is_alive;
2147 ShenandoahUpdateRefsClosure keep_alive;
2148 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2149 cleaning_task(&is_alive, &keep_alive, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2150 _workers->run_task(&cleaning_task);
2151 } else {
2152 ShenandoahIsAliveClosure is_alive;
2153 #ifdef ASSERT
2154 ShenandoahAssertNotForwardedClosure verify_cl;
2155 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2156 cleaning_task(&is_alive, &verify_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2157 #else
2158 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2159 cleaning_task(&is_alive, &do_nothing_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2160 #endif
2161 _workers->run_task(&cleaning_task);
2162 }
2163 }
2164
2165 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2166 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2167 stw_process_weak_roots(full_gc);
2168 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2169 stw_unload_classes(full_gc);
2170 }
2171 }
2172
2173 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2174 set_gc_state_mask(HAS_FORWARDED, cond);
2175 }
2176
2177 void ShenandoahHeap::set_process_references(bool pr) {
2178 _process_references.set_cond(pr);
2179 }
2180
2181 void ShenandoahHeap::set_unload_classes(bool uc) {
2182 _unload_classes.set_cond(uc);
2183 }
2184
2185 bool ShenandoahHeap::process_references() const {
2186 return _process_references.is_set();
2187 }
2188
2189 bool ShenandoahHeap::unload_classes() const {
2190 return _unload_classes.is_set();
2191 }
2192
2193 address ShenandoahHeap::in_cset_fast_test_addr() {
2194 ShenandoahHeap* heap = ShenandoahHeap::heap();
2195 assert(heap->collection_set() != NULL, "Sanity");
2196 return (address) heap->collection_set()->biased_map_address();
2197 }
2198
2199 address ShenandoahHeap::cancelled_gc_addr() {
2200 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
2201 }
2202
2203 address ShenandoahHeap::gc_state_addr() {
2204 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2205 }
2206
2207 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2208 return Atomic::load_acquire(&_bytes_allocated_since_gc_start);
2209 }
2210
2211 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2212 Atomic::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2213 }
2214
2215 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2216 _degenerated_gc_in_progress.set_cond(in_progress);
2217 }
2218
2219 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2220 _full_gc_in_progress.set_cond(in_progress);
2221 }
2222
2223 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2224 assert (is_full_gc_in_progress(), "should be");
2225 _full_gc_move_in_progress.set_cond(in_progress);
2226 }
2227
2228 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2229 set_gc_state_mask(UPDATEREFS, in_progress);
2230 }
2231
2232 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2233 ShenandoahCodeRoots::register_nmethod(nm);
2234 }
2235
2236 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2237 ShenandoahCodeRoots::unregister_nmethod(nm);
2238 }
2239
2240 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
2241 ShenandoahCodeRoots::flush_nmethod(nm);
2242 }
2243
2244 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2245 heap_region_containing(o)->record_pin();
2246 return o;
2247 }
2248
2249 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2250 heap_region_containing(o)->record_unpin();
2251 }
2252
2253 void ShenandoahHeap::sync_pinned_region_status() {
2254 ShenandoahHeapLocker locker(lock());
2255
2256 for (size_t i = 0; i < num_regions(); i++) {
2257 ShenandoahHeapRegion *r = get_region(i);
2258 if (r->is_active()) {
2259 if (r->is_pinned()) {
2260 if (r->pin_count() == 0) {
2261 r->make_unpinned();
2262 }
2263 } else {
2264 if (r->pin_count() > 0) {
2265 r->make_pinned();
2266 }
2267 }
2268 }
2269 }
2270
2271 assert_pinned_region_status();
2272 }
2273
2274 #ifdef ASSERT
2275 void ShenandoahHeap::assert_pinned_region_status() {
2276 for (size_t i = 0; i < num_regions(); i++) {
2277 ShenandoahHeapRegion* r = get_region(i);
2278 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2279 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2280 }
2281 }
2282 #endif
2283
2284 GCTimer* ShenandoahHeap::gc_timer() const {
2285 return _gc_timer;
2286 }
2287
2288 void ShenandoahHeap::prepare_concurrent_roots() {
2289 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2290 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
2291 set_concurrent_root_in_progress(true);
2292 }
2293 }
2294
2295 void ShenandoahHeap::prepare_concurrent_unloading() {
2296 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2297 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2298 _unloader.prepare();
2299 }
2300 }
2301
2302 void ShenandoahHeap::finish_concurrent_unloading() {
2303 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2304 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2305 _unloader.finish();
2306 }
2307 }
2308
2309 #ifdef ASSERT
2310 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2311 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2312
2313 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2314 if (UseDynamicNumberOfGCThreads) {
2315 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2316 } else {
2317 // Use ParallelGCThreads inside safepoints
2318 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
2319 }
2320 } else {
2321 if (UseDynamicNumberOfGCThreads) {
2322 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2323 } else {
2324 // Use ConcGCThreads outside safepoints
2325 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2326 }
2327 }
2328 }
2329 #endif
2330
2331 ShenandoahVerifier* ShenandoahHeap::verifier() {
2332 guarantee(ShenandoahVerify, "Should be enabled");
2333 assert (_verifier != NULL, "sanity");
2334 return _verifier;
2335 }
2336
2337 template<class T>
2338 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2339 private:
2340 T cl;
2341 ShenandoahHeap* _heap;
2342 ShenandoahRegionIterator* _regions;
2343 bool _concurrent;
2344 public:
2345 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2346 AbstractGangTask("Concurrent Update References Task"),
2347 cl(T()),
2348 _heap(ShenandoahHeap::heap()),
2349 _regions(regions),
2350 _concurrent(concurrent) {
2351 }
2352
2353 void work(uint worker_id) {
2354 if (_concurrent) {
2355 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2356 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2357 do_work();
2358 } else {
2359 ShenandoahParallelWorkerSession worker_session(worker_id);
2360 do_work();
2361 }
2362 }
2363
2364 private:
2365 void do_work() {
2366 ShenandoahHeapRegion* r = _regions->next();
2367 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2368 while (r != NULL) {
2369 HeapWord* update_watermark = r->get_update_watermark();
2370 assert (update_watermark >= r->bottom(), "sanity");
2371 if (r->is_active() && !r->is_cset()) {
2372 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2373 }
2374 if (ShenandoahPacing) {
2375 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2376 }
2377 if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
2378 return;
2379 }
2380 r = _regions->next();
2381 }
2382 }
2383 };
2384
2385 void ShenandoahHeap::update_heap_references(bool concurrent) {
2386 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
2387 workers()->run_task(&task);
2388 }
2389
2390 void ShenandoahHeap::op_init_updaterefs() {
2391 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2392
2393 set_evacuation_in_progress(false);
2394
2395 {
2396 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_retire_gclabs);
2397 retire_and_reset_gclabs();
2398 }
2399
2400 if (ShenandoahVerify) {
2401 if (!is_degenerated_gc_in_progress()) {
2402 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2403 }
2404 verifier()->verify_before_updaterefs();
2405 }
2406
2407 set_update_refs_in_progress(true);
2408
2409 {
2410 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_prepare);
2411
2412 make_parsable(true);
2413
2414 // Reset iterator.
2415 _update_refs_iterator.reset();
2416 }
2417
2418 if (ShenandoahPacing) {
2419 pacer()->setup_for_updaterefs();
2420 }
2421 }
2422
2423 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2424 private:
2425 ShenandoahHeapLock* const _lock;
2426
2427 public:
2428 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2429
2430 void heap_region_do(ShenandoahHeapRegion* r) {
2431 // Drop unnecessary "pinned" state from regions that does not have CP marks
2432 // anymore, as this would allow trashing them.
2433
2434 if (r->is_active()) {
2435 if (r->is_pinned()) {
2436 if (r->pin_count() == 0) {
2437 ShenandoahHeapLocker locker(_lock);
2438 r->make_unpinned();
2439 }
2440 } else {
2441 if (r->pin_count() > 0) {
2442 ShenandoahHeapLocker locker(_lock);
2443 r->make_pinned();
2444 }
2445 }
2446 }
2447 }
2448
2449 bool is_thread_safe() { return true; }
2450 };
2451
2452 void ShenandoahHeap::op_final_updaterefs() {
2453 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2454
2455 finish_concurrent_unloading();
2456
2457 // Check if there is left-over work, and finish it
2458 if (_update_refs_iterator.has_next()) {
2459 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2460
2461 // Finish updating references where we left off.
2462 clear_cancelled_gc();
2463 update_heap_references(false);
2464 }
2465
2466 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2467 // everything. On degenerated paths, cancelled gc would not be set anyway.
2468 if (cancelled_gc()) {
2469 clear_cancelled_gc();
2470 }
2471 assert(!cancelled_gc(), "Should have been done right before");
2472
2473 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2474 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2475 }
2476
2477 if (is_degenerated_gc_in_progress()) {
2478 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2479 } else {
2480 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2481 }
2482
2483 // Has to be done before cset is clear
2484 if (ShenandoahVerify) {
2485 verifier()->verify_roots_in_to_space();
2486 }
2487
2488 {
2489 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_update_region_states);
2490 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2491 parallel_heap_region_iterate(&cl);
2492
2493 assert_pinned_region_status();
2494 }
2495
2496 {
2497 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2498 trash_cset_regions();
2499 }
2500
2501 set_has_forwarded_objects(false);
2502 set_update_refs_in_progress(false);
2503
2504 if (ShenandoahVerify) {
2505 verifier()->verify_after_updaterefs();
2506 }
2507
2508 if (VerifyAfterGC) {
2509 Universe::verify();
2510 }
2511
2512 {
2513 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_rebuild_freeset);
2514 ShenandoahHeapLocker locker(lock());
2515 _free_set->rebuild();
2516 }
2517 }
2518
2519 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2520 print_on(st);
2521 print_heap_regions_on(st);
2522 }
2523
2524 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2525 size_t slice = r->index() / _bitmap_regions_per_slice;
2526
2527 size_t regions_from = _bitmap_regions_per_slice * slice;
2528 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2529 for (size_t g = regions_from; g < regions_to; g++) {
2530 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2531 if (skip_self && g == r->index()) continue;
2532 if (get_region(g)->is_committed()) {
2533 return true;
2534 }
2535 }
2536 return false;
2537 }
2538
2539 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2540 shenandoah_assert_heaplocked();
2541
2542 // Bitmaps in special regions do not need commits
2543 if (_bitmap_region_special) {
2544 return true;
2545 }
2546
2547 if (is_bitmap_slice_committed(r, true)) {
2548 // Some other region from the group is already committed, meaning the bitmap
2549 // slice is already committed, we exit right away.
2550 return true;
2551 }
2552
2553 // Commit the bitmap slice:
2554 size_t slice = r->index() / _bitmap_regions_per_slice;
2555 size_t off = _bitmap_bytes_per_slice * slice;
2556 size_t len = _bitmap_bytes_per_slice;
2557 if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) {
2558 return false;
2559 }
2560 return true;
2561 }
2562
2563 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2564 shenandoah_assert_heaplocked();
2565
2566 // Bitmaps in special regions do not need uncommits
2567 if (_bitmap_region_special) {
2568 return true;
2569 }
2570
2571 if (is_bitmap_slice_committed(r, true)) {
2572 // Some other region from the group is still committed, meaning the bitmap
2573 // slice is should stay committed, exit right away.
2574 return true;
2575 }
2576
2577 // Uncommit the bitmap slice:
2578 size_t slice = r->index() / _bitmap_regions_per_slice;
2579 size_t off = _bitmap_bytes_per_slice * slice;
2580 size_t len = _bitmap_bytes_per_slice;
2581 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2582 return false;
2583 }
2584 return true;
2585 }
2586
2587 void ShenandoahHeap::safepoint_synchronize_begin() {
2588 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2589 SuspendibleThreadSet::synchronize();
2590 }
2591 }
2592
2593 void ShenandoahHeap::safepoint_synchronize_end() {
2594 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2595 SuspendibleThreadSet::desynchronize();
2596 }
2597 }
2598
2599 void ShenandoahHeap::vmop_entry_init_mark() {
2600 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2601 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2602 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
2603
2604 try_inject_alloc_failure();
2605 VM_ShenandoahInitMark op;
2606 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2607 }
2608
2609 void ShenandoahHeap::vmop_entry_final_mark() {
2610 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2611 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2612 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
2613
2614 try_inject_alloc_failure();
2615 VM_ShenandoahFinalMarkStartEvac op;
2616 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2617 }
2618
2619 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2620 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2621 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2622 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
2623
2624 try_inject_alloc_failure();
2625 VM_ShenandoahInitUpdateRefs op;
2626 VMThread::execute(&op);
2627 }
2628
2629 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2630 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2631 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2632 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
2633
2634 try_inject_alloc_failure();
2635 VM_ShenandoahFinalUpdateRefs op;
2636 VMThread::execute(&op);
2637 }
2638
2639 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2640 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2641 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2642 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
2643
2644 try_inject_alloc_failure();
2645 VM_ShenandoahFullGC op(cause);
2646 VMThread::execute(&op);
2647 }
2648
2649 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2650 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2651 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2652 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
2653
2654 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2655 VMThread::execute(°enerated_gc);
2656 }
2657
2658 void ShenandoahHeap::entry_init_mark() {
2659 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2660 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
2661 const char* msg = init_mark_event_message();
2662 GCTraceTime(Info, gc) time(msg, gc_timer());
2663 EventMark em("%s", msg);
2664
2665 ShenandoahWorkerScope scope(workers(),
2666 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2667 "init marking");
2668
2669 op_init_mark();
2670 }
2671
2672 void ShenandoahHeap::entry_final_mark() {
2673 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2674 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
2675 const char* msg = final_mark_event_message();
2676 GCTraceTime(Info, gc) time(msg, gc_timer());
2677 EventMark em("%s", msg);
2678
2679 ShenandoahWorkerScope scope(workers(),
2680 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2681 "final marking");
2682
2683 op_final_mark();
2684 }
2685
2686 void ShenandoahHeap::entry_init_updaterefs() {
2687 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2688 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
2689
2690 static const char* msg = "Pause Init Update Refs";
2691 GCTraceTime(Info, gc) time(msg, gc_timer());
2692 EventMark em("%s", msg);
2693
2694 // No workers used in this phase, no setup required
2695
2696 op_init_updaterefs();
2697 }
2698
2699 void ShenandoahHeap::entry_final_updaterefs() {
2700 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2701 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
2702
2703 static const char* msg = "Pause Final Update Refs";
2704 GCTraceTime(Info, gc) time(msg, gc_timer());
2705 EventMark em("%s", msg);
2706
2707 ShenandoahWorkerScope scope(workers(),
2708 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2709 "final reference update");
2710
2711 op_final_updaterefs();
2712 }
2713
2714 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2715 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2716 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
2717
2718 static const char* msg = "Pause Full";
2719 GCTraceTime(Info, gc) time(msg, gc_timer(), cause, true);
2720 EventMark em("%s", msg);
2721
2722 ShenandoahWorkerScope scope(workers(),
2723 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2724 "full gc");
2725
2726 op_full(cause);
2727 }
2728
2729 void ShenandoahHeap::entry_degenerated(int point) {
2730 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2731 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
2732
2733 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2734 const char* msg = degen_event_message(dpoint);
2735 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2736 EventMark em("%s", msg);
2737
2738 ShenandoahWorkerScope scope(workers(),
2739 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2740 "stw degenerated gc");
2741
2742 set_degenerated_gc_in_progress(true);
2743 op_degenerated(dpoint);
2744 set_degenerated_gc_in_progress(false);
2745 }
2746
2747 void ShenandoahHeap::entry_mark() {
2748 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2749
2750 const char* msg = conc_mark_event_message();
2751 GCTraceTime(Info, gc) time(msg);
2752 EventMark em("%s", msg);
2753
2754 ShenandoahWorkerScope scope(workers(),
2755 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2756 "concurrent marking");
2757
2758 try_inject_alloc_failure();
2759 op_mark();
2760 }
2761
2762 void ShenandoahHeap::entry_evac() {
2763 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
2764 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2765
2766 static const char* msg = "Concurrent evacuation";
2767 GCTraceTime(Info, gc) time(msg);
2768 EventMark em("%s", msg);
2769
2770 ShenandoahWorkerScope scope(workers(),
2771 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2772 "concurrent evacuation");
2773
2774 try_inject_alloc_failure();
2775 op_conc_evac();
2776 }
2777
2778 void ShenandoahHeap::entry_updaterefs() {
2779 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
2780
2781 static const char* msg = "Concurrent update references";
2782 GCTraceTime(Info, gc) time(msg);
2783 EventMark em("%s", msg);
2784
2785 ShenandoahWorkerScope scope(workers(),
2786 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2787 "concurrent reference update");
2788
2789 try_inject_alloc_failure();
2790 op_updaterefs();
2791 }
2792
2793 void ShenandoahHeap::entry_roots() {
2794 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_roots);
2795
2796 static const char* msg = "Concurrent roots processing";
2797 GCTraceTime(Info, gc) time(msg);
2798 EventMark em("%s", msg);
2799
2800 ShenandoahWorkerScope scope(workers(),
2801 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2802 "concurrent root processing");
2803
2804 try_inject_alloc_failure();
2805 op_roots();
2806 }
2807
2808 void ShenandoahHeap::entry_cleanup() {
2809 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup);
2810
2811 static const char* msg = "Concurrent cleanup";
2812 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2813 EventMark em("%s", msg);
2814
2815 // This phase does not use workers, no need for setup
2816
2817 try_inject_alloc_failure();
2818 op_cleanup();
2819 }
2820
2821 void ShenandoahHeap::entry_reset() {
2822 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset);
2823
2824 static const char* msg = "Concurrent reset";
2825 GCTraceTime(Info, gc) time(msg);
2826 EventMark em("%s", msg);
2827
2828 ShenandoahWorkerScope scope(workers(),
2829 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2830 "concurrent reset");
2831
2832 try_inject_alloc_failure();
2833 op_reset();
2834 }
2835
2836 void ShenandoahHeap::entry_preclean() {
2837 if (ShenandoahPreclean && process_references()) {
2838 static const char* msg = "Concurrent precleaning";
2839 GCTraceTime(Info, gc) time(msg);
2840 EventMark em("%s", msg);
2841
2842 ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
2843
2844 ShenandoahWorkerScope scope(workers(),
2845 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2846 "concurrent preclean",
2847 /* check_workers = */ false);
2848
2849 try_inject_alloc_failure();
2850 op_preclean();
2851 }
2852 }
2853
2854 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2855 static const char *msg = "Concurrent uncommit";
2856 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2857 EventMark em("%s", msg);
2858
2859 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit);
2860
2861 op_uncommit(shrink_before);
2862 }
2863
2864 void ShenandoahHeap::try_inject_alloc_failure() {
2865 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2866 _inject_alloc_failure.set();
2867 os::naked_short_sleep(1);
2868 if (cancelled_gc()) {
2869 log_info(gc)("Allocation failure was successfully injected");
2870 }
2871 }
2872 }
2873
2874 bool ShenandoahHeap::should_inject_alloc_failure() {
2875 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2876 }
2877
2878 void ShenandoahHeap::initialize_serviceability() {
2879 _memory_pool = new ShenandoahMemoryPool(this);
2880 _cycle_memory_manager.add_pool(_memory_pool);
2881 _stw_memory_manager.add_pool(_memory_pool);
2882 }
2883
2884 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2885 GrowableArray<GCMemoryManager*> memory_managers(2);
2886 memory_managers.append(&_cycle_memory_manager);
2887 memory_managers.append(&_stw_memory_manager);
2888 return memory_managers;
2889 }
2890
2891 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2892 GrowableArray<MemoryPool*> memory_pools(1);
2893 memory_pools.append(_memory_pool);
2894 return memory_pools;
2895 }
2896
2897 MemoryUsage ShenandoahHeap::memory_usage() {
2898 return _memory_pool->get_memory_usage();
2899 }
2900
2901 void ShenandoahHeap::enter_evacuation() {
2902 _oom_evac_handler.enter_evacuation();
2903 }
2904
2905 void ShenandoahHeap::leave_evacuation() {
2906 _oom_evac_handler.leave_evacuation();
2907 }
2908
2909 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2910 _heap(ShenandoahHeap::heap()),
2911 _index(0) {}
2912
2913 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2914 _heap(heap),
2915 _index(0) {}
2916
2917 void ShenandoahRegionIterator::reset() {
2918 _index = 0;
2919 }
2920
2921 bool ShenandoahRegionIterator::has_next() const {
2922 return _index < _heap->num_regions();
2923 }
2924
2925 char ShenandoahHeap::gc_state() const {
2926 return _gc_state.raw_value();
2927 }
2928
2929 void ShenandoahHeap::deduplicate_string(oop str) {
2930 assert(java_lang_String::is_instance(str), "invariant");
2931
2932 if (ShenandoahStringDedup::is_enabled()) {
2933 ShenandoahStringDedup::deduplicate(str);
2934 }
2935 }
2936
2937 const char* ShenandoahHeap::init_mark_event_message() const {
2938 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
2939
2940 bool proc_refs = process_references();
2941 bool unload_cls = unload_classes();
2942
2943 if (proc_refs && unload_cls) {
2944 return "Pause Init Mark (process weakrefs) (unload classes)";
2945 } else if (proc_refs) {
2946 return "Pause Init Mark (process weakrefs)";
2947 } else if (unload_cls) {
2948 return "Pause Init Mark (unload classes)";
2949 } else {
2950 return "Pause Init Mark";
2951 }
2952 }
2953
2954 const char* ShenandoahHeap::final_mark_event_message() const {
2955 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
2956
2957 bool proc_refs = process_references();
2958 bool unload_cls = unload_classes();
2959
2960 if (proc_refs && unload_cls) {
2961 return "Pause Final Mark (process weakrefs) (unload classes)";
2962 } else if (proc_refs) {
2963 return "Pause Final Mark (process weakrefs)";
2964 } else if (unload_cls) {
2965 return "Pause Final Mark (unload classes)";
2966 } else {
2967 return "Pause Final Mark";
2968 }
2969 }
2970
2971 const char* ShenandoahHeap::conc_mark_event_message() const {
2972 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
2973
2974 bool proc_refs = process_references();
2975 bool unload_cls = unload_classes();
2976
2977 if (proc_refs && unload_cls) {
2978 return "Concurrent marking (process weakrefs) (unload classes)";
2979 } else if (proc_refs) {
2980 return "Concurrent marking (process weakrefs)";
2981 } else if (unload_cls) {
2982 return "Concurrent marking (unload classes)";
2983 } else {
2984 return "Concurrent marking";
2985 }
2986 }
2987
2988 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
2989 switch (point) {
2990 case _degenerated_unset:
2991 return "Pause Degenerated GC (<UNSET>)";
2992 case _degenerated_outside_cycle:
2993 return "Pause Degenerated GC (Outside of Cycle)";
2994 case _degenerated_mark:
2995 return "Pause Degenerated GC (Mark)";
2996 case _degenerated_evac:
2997 return "Pause Degenerated GC (Evacuation)";
2998 case _degenerated_updaterefs:
2999 return "Pause Degenerated GC (Update Refs)";
3000 default:
3001 ShouldNotReachHere();
3002 return "ERROR";
3003 }
3004 }
3005
3006 jushort* ShenandoahHeap::get_liveness_cache(uint worker_id) {
3007 #ifdef ASSERT
3008 assert(_liveness_cache != NULL, "sanity");
3009 assert(worker_id < _max_workers, "sanity");
3010 for (uint i = 0; i < num_regions(); i++) {
3011 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
3012 }
3013 #endif
3014 return _liveness_cache[worker_id];
3015 }
3016
3017 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
3018 assert(worker_id < _max_workers, "sanity");
3019 assert(_liveness_cache != NULL, "sanity");
3020 jushort* ld = _liveness_cache[worker_id];
3021 for (uint i = 0; i < num_regions(); i++) {
3022 ShenandoahHeapRegion* r = get_region(i);
3023 jushort live = ld[i];
3024 if (live > 0) {
3025 r->increase_live_data_gc_words(live);
3026 ld[i] = 0;
3027 }
3028 }
3029 }