1 /*
2 * Copyright (c) 2013, 2018, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #include "precompiled.hpp"
25 #include "memory/allocation.hpp"
26
27 #include "gc_implementation/shared/gcTimer.hpp"
28 #include "gc_implementation/shenandoah/shenandoahGCTraceTime.hpp"
29 #include "gc_implementation/shared/parallelCleaning.hpp"
30
31 #include "gc_implementation/shenandoah/shenandoahBrooksPointer.hpp"
32 #include "gc_implementation/shenandoah/shenandoahAllocTracker.hpp"
33 #include "gc_implementation/shenandoah/shenandoahBarrierSet.hpp"
34 #include "gc_implementation/shenandoah/shenandoahCollectionSet.hpp"
35 #include "gc_implementation/shenandoah/shenandoahCollectorPolicy.hpp"
36 #include "gc_implementation/shenandoah/shenandoahConcurrentMark.inline.hpp"
37 #include "gc_implementation/shenandoah/shenandoahControlThread.hpp"
38 #include "gc_implementation/shenandoah/shenandoahFreeSet.hpp"
39 #include "gc_implementation/shenandoah/shenandoahPhaseTimings.hpp"
40 #include "gc_implementation/shenandoah/shenandoahHeap.inline.hpp"
41 #include "gc_implementation/shenandoah/shenandoahHeapRegion.hpp"
42 #include "gc_implementation/shenandoah/shenandoahHeapRegionSet.hpp"
43 #include "gc_implementation/shenandoah/shenandoahMarkCompact.hpp"
44 #include "gc_implementation/shenandoah/shenandoahMarkingContext.inline.hpp"
45 #include "gc_implementation/shenandoah/shenandoahMonitoringSupport.hpp"
46 #include "gc_implementation/shenandoah/shenandoahMetrics.hpp"
47 #include "gc_implementation/shenandoah/shenandoahOopClosures.inline.hpp"
48 #include "gc_implementation/shenandoah/shenandoahPacer.inline.hpp"
49 #include "gc_implementation/shenandoah/shenandoahRootProcessor.hpp"
50 #include "gc_implementation/shenandoah/shenandoahUtils.hpp"
51 #include "gc_implementation/shenandoah/shenandoahVerifier.hpp"
52 #include "gc_implementation/shenandoah/shenandoahCodeRoots.hpp"
53 #include "gc_implementation/shenandoah/shenandoahVMOperations.hpp"
54 #include "gc_implementation/shenandoah/shenandoahWorkGroup.hpp"
55 #include "gc_implementation/shenandoah/shenandoahWorkerPolicy.hpp"
56 #include "gc_implementation/shenandoah/heuristics/shenandoahAdaptiveHeuristics.hpp"
57 #include "gc_implementation/shenandoah/heuristics/shenandoahAggressiveHeuristics.hpp"
58 #include "gc_implementation/shenandoah/heuristics/shenandoahCompactHeuristics.hpp"
59 #include "gc_implementation/shenandoah/heuristics/shenandoahPassiveHeuristics.hpp"
60 #include "gc_implementation/shenandoah/heuristics/shenandoahStaticHeuristics.hpp"
61
62 #include "memory/metaspace.hpp"
63 #include "runtime/vmThread.hpp"
64 #include "services/mallocTracker.hpp"
65
66 ShenandoahUpdateRefsClosure::ShenandoahUpdateRefsClosure() : _heap(ShenandoahHeap::heap()) {}
67
68 #ifdef ASSERT
69 template <class T>
70 void ShenandoahAssertToSpaceClosure::do_oop_nv(T* p) {
71 T o = oopDesc::load_heap_oop(p);
72 if (! oopDesc::is_null(o)) {
73 oop obj = oopDesc::decode_heap_oop_not_null(o);
74 shenandoah_assert_not_forwarded(p, obj);
75 }
76 }
77
78 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_nv(p); }
79 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_nv(p); }
80 #endif
81
82 class ShenandoahPretouchTask : public AbstractGangTask {
83 private:
84 ShenandoahRegionIterator _regions;
85 const size_t _bitmap_size;
86 const size_t _page_size;
87 char* _bitmap_base;
88 public:
89 ShenandoahPretouchTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
90 AbstractGangTask("Shenandoah PreTouch"),
91 _bitmap_size(bitmap_size),
92 _page_size(page_size),
93 _bitmap_base(bitmap_base) {}
94
95 virtual void work(uint worker_id) {
96 ShenandoahHeapRegion* r = _regions.next();
97 while (r != NULL) {
98 os::pretouch_memory((char*) r->bottom(), (char*) r->end());
99
100 size_t start = r->region_number() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
101 size_t end = (r->region_number() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
102 assert (end <= _bitmap_size, err_msg("end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size));
103
104 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end);
105
106 r = _regions.next();
107 }
108 }
109 };
110
111 jint ShenandoahHeap::initialize() {
112 CollectedHeap::pre_initialize();
113
114 ShenandoahBrooksPointer::initial_checks();
115
116 initialize_heuristics();
117
118 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
119 size_t max_byte_size = collector_policy()->max_heap_byte_size();
120 size_t heap_alignment = collector_policy()->heap_alignment();
121
122 if (ShenandoahAlwaysPreTouch) {
123 // Enabled pre-touch means the entire heap is committed right away.
124 init_byte_size = max_byte_size;
125 }
126
127 Universe::check_alignment(max_byte_size,
128 ShenandoahHeapRegion::region_size_bytes(),
129 "shenandoah heap");
130 Universe::check_alignment(init_byte_size,
131 ShenandoahHeapRegion::region_size_bytes(),
132 "shenandoah heap");
133
134 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
135 heap_alignment);
136
137 _reserved.set_word_size(0);
138 _reserved.set_start((HeapWord*)heap_rs.base());
139 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
140
141 set_barrier_set(new ShenandoahBarrierSet(this));
142 ReservedSpace pgc_rs = heap_rs.first_part(max_byte_size);
143
144 _num_regions = ShenandoahHeapRegion::region_count();
145
146 size_t num_committed_regions = init_byte_size / ShenandoahHeapRegion::region_size_bytes();
147 num_committed_regions = MIN2(num_committed_regions, _num_regions);
148 assert(num_committed_regions <= _num_regions, "sanity");
149
150 _initial_size = num_committed_regions * ShenandoahHeapRegion::region_size_bytes();
151 _committed = _initial_size;
152
153 log_info(gc, heap)("Initialize Shenandoah heap with initial size " SIZE_FORMAT "%s",
154 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size));
155 if (!os::commit_memory(pgc_rs.base(), _initial_size, false)) {
156 vm_exit_out_of_memory(_initial_size, OOM_MMAP_ERROR, "Shenandoah failed to initialize heap");
157 }
158
159 size_t reg_size_words = ShenandoahHeapRegion::region_size_words();
160 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
161
162 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
163 _free_set = new ShenandoahFreeSet(this, _num_regions);
164
165 _collection_set = new ShenandoahCollectionSet(this, (HeapWord*)pgc_rs.base());
166
167 if (ShenandoahPacing) {
168 _pacer = new ShenandoahPacer(this);
169 _pacer->setup_for_idle();
170 } else {
171 _pacer = NULL;
172 }
173
174 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
175 err_msg("misaligned heap: " PTR_FORMAT, p2i(base())));
176
177 // The call below uses stuff (the SATB* things) that are in G1, but probably
178 // belong into a shared location.
179 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
180 SATB_Q_FL_lock,
181 20 /*G1SATBProcessCompletedThreshold */,
182 Shared_SATB_Q_lock);
183
184 // Reserve space for prev and next bitmap.
185 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
186 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
187 _bitmap_size = align_size_up(_bitmap_size, bitmap_page_size);
188 _heap_region = MemRegion((HeapWord*) heap_rs.base(), heap_rs.size() / HeapWordSize);
189
190 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
191
192 guarantee(bitmap_bytes_per_region != 0,
193 err_msg("Bitmap bytes per region should not be zero"));
194 guarantee(is_power_of_2(bitmap_bytes_per_region),
195 err_msg("Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region));
196
197 if (bitmap_page_size > bitmap_bytes_per_region) {
198 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
199 _bitmap_bytes_per_slice = bitmap_page_size;
200 } else {
201 _bitmap_regions_per_slice = 1;
202 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
203 }
204
205 guarantee(_bitmap_regions_per_slice >= 1,
206 err_msg("Should have at least one region per slice: " SIZE_FORMAT,
207 _bitmap_regions_per_slice));
208
209 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
210 err_msg("Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
211 _bitmap_bytes_per_slice, bitmap_page_size));
212
213 ReservedSpace bitmap0(_bitmap_size, bitmap_page_size);
214 MemTracker::record_virtual_memory_type(bitmap0.base(), mtGC);
215 _bitmap_region = MemRegion((HeapWord*) bitmap0.base(), bitmap0.size() / HeapWordSize);
216
217 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
218 align_size_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
219 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
220 os::commit_memory_or_exit((char *) (_bitmap_region.start()), bitmap_init_commit, false,
221 "couldn't allocate initial bitmap");
222
223 size_t page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
224
225 if (ShenandoahVerify) {
226 ReservedSpace verify_bitmap(_bitmap_size, page_size);
227 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), false,
228 "couldn't allocate verification bitmap");
229 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
230 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
231 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
232 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
233 }
234
235 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
236
237 {
238 ShenandoahHeapLocker locker(lock());
239 for (size_t i = 0; i < _num_regions; i++) {
240 ShenandoahHeapRegion* r = new ShenandoahHeapRegion(this,
241 (HeapWord*) pgc_rs.base() + reg_size_words * i,
242 reg_size_words,
243 i,
244 i < num_committed_regions);
245
246 _marking_context->initialize_top_at_mark_start(r);
247 _regions[i] = r;
248 assert(!collection_set()->is_in(i), "New region should not be in collection set");
249 }
250
251 // Initialize to complete
252 _marking_context->mark_complete();
253
254 _free_set->rebuild();
255 }
256
257 if (ShenandoahAlwaysPreTouch) {
258 assert (!AlwaysPreTouch, "Should have been overridden");
259
260 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
261 // before initialize() below zeroes it with initializing thread. For any given region,
262 // we touch the region and the corresponding bitmaps from the same thread.
263 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
264
265 log_info(gc, heap)("Parallel pretouch " SIZE_FORMAT " regions with " SIZE_FORMAT " byte pages",
266 _num_regions, page_size);
267 ShenandoahPretouchTask cl(bitmap0.base(), _bitmap_size, page_size);
268 _workers->run_task(&cl);
269 }
270
271 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
272 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
273 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
274 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
275 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
276
277 _monitoring_support = new ShenandoahMonitoringSupport(this);
278
279 _phase_timings = new ShenandoahPhaseTimings();
280
281 if (ShenandoahAllocationTrace) {
282 _alloc_tracker = new ShenandoahAllocTracker();
283 }
284
285 ShenandoahStringDedup::initialize();
286
287 _control_thread = new ShenandoahControlThread();
288
289 ShenandoahCodeRoots::initialize();
290
291 _liveness_cache = NEW_C_HEAP_ARRAY(jushort*, _max_workers, mtGC);
292 for (uint worker = 0; worker < _max_workers; worker++) {
293 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(jushort, _num_regions, mtGC);
294 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(jushort));
295 }
296
297 return JNI_OK;
298 }
299
300 #ifdef _MSC_VER
301 #pragma warning( push )
302 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
303 #endif
304
305 void ShenandoahHeap::initialize_heuristics() {
306 if (ShenandoahGCHeuristics != NULL) {
307 if (strcmp(ShenandoahGCHeuristics, "aggressive") == 0) {
308 _heuristics = new ShenandoahAggressiveHeuristics();
309 } else if (strcmp(ShenandoahGCHeuristics, "static") == 0) {
310 _heuristics = new ShenandoahStaticHeuristics();
311 } else if (strcmp(ShenandoahGCHeuristics, "adaptive") == 0) {
312 _heuristics = new ShenandoahAdaptiveHeuristics();
313 } else if (strcmp(ShenandoahGCHeuristics, "passive") == 0) {
314 _heuristics = new ShenandoahPassiveHeuristics();
315 } else if (strcmp(ShenandoahGCHeuristics, "compact") == 0) {
316 _heuristics = new ShenandoahCompactHeuristics();
317 } else {
318 vm_exit_during_initialization("Unknown -XX:ShenandoahGCHeuristics option");
319 }
320
321 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
322 vm_exit_during_initialization(
323 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
324 _heuristics->name()));
325 }
326 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
327 vm_exit_during_initialization(
328 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
329 _heuristics->name()));
330 }
331 log_info(gc, init)("Shenandoah heuristics: %s",
332 _heuristics->name());
333 } else {
334 ShouldNotReachHere();
335 }
336 }
337
338 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
339 SharedHeap(policy),
340 _shenandoah_policy(policy),
341 _regions(NULL),
342 _free_set(NULL),
343 _collection_set(NULL),
344 _update_refs_iterator(this),
345 _bytes_allocated_since_gc_start(0),
346 _max_workers((uint)MAX2(ConcGCThreads, ParallelGCThreads)),
347 _ref_processor(NULL),
348 _marking_context(NULL),
349 _aux_bit_map(),
350 _verifier(NULL),
351 _pacer(NULL),
352 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
353 _phase_timings(NULL),
354 _alloc_tracker(NULL)
355 {
356 log_info(gc, init)("GC threads: " UINTX_FORMAT " parallel, " UINTX_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
357 log_info(gc, init)("Reference processing: %s", ParallelRefProcEnabled ? "parallel" : "serial");
358
359 _scm = new ShenandoahConcurrentMark();
360 _full_gc = new ShenandoahMarkCompact();
361 _used = 0;
362
363 _max_workers = MAX2(_max_workers, 1U);
364 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
365 /* are_GC_task_threads */true,
366 /* are_ConcurrentGC_threads */false);
367 if (_workers == NULL) {
368 vm_exit_during_initialization("Failed necessary allocation.");
369 } else {
370 _workers->initialize_workers();
371 }
372 }
373
374 #ifdef _MSC_VER
375 #pragma warning( pop )
376 #endif
377
378 class ShenandoahResetBitmapTask : public AbstractGangTask {
379 private:
380 ShenandoahRegionIterator _regions;
381
382 public:
383 ShenandoahResetBitmapTask() :
384 AbstractGangTask("Parallel Reset Bitmap Task") {}
385
386 void work(uint worker_id) {
387 ShenandoahHeapRegion* region = _regions.next();
388 ShenandoahHeap* heap = ShenandoahHeap::heap();
389 ShenandoahMarkingContext* const ctx = heap->marking_context();
390 while (region != NULL) {
391 if (heap->is_bitmap_slice_committed(region)) {
392 ctx->clear_bitmap(region);
393 }
394 region = _regions.next();
395 }
396 }
397 };
398
399 void ShenandoahHeap::reset_mark_bitmap() {
400 assert_gc_workers(_workers->active_workers());
401 mark_incomplete_marking_context();
402
403 ShenandoahResetBitmapTask task;
404 _workers->run_task(&task);
405 }
406
407 void ShenandoahHeap::print_on(outputStream* st) const {
408 st->print_cr("Shenandoah Heap");
409 st->print_cr(" " SIZE_FORMAT "K total, " SIZE_FORMAT "K committed, " SIZE_FORMAT "K used",
410 capacity() / K, committed() / K, used() / K);
411 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"K regions",
412 num_regions(), ShenandoahHeapRegion::region_size_bytes() / K);
413
414 st->print("Status: ");
415 if (has_forwarded_objects()) st->print("has forwarded objects, ");
416 if (is_concurrent_mark_in_progress()) st->print("marking, ");
417 if (is_evacuation_in_progress()) st->print("evacuating, ");
418 if (is_update_refs_in_progress()) st->print("updating refs, ");
419 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
420 if (is_full_gc_in_progress()) st->print("full gc, ");
421 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
422
423 if (cancelled_gc()) {
424 st->print("cancelled");
425 } else {
426 st->print("not cancelled");
427 }
428 st->cr();
429
430 st->print_cr("Reserved region:");
431 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
432 p2i(reserved_region().start()),
433 p2i(reserved_region().end()));
434
435 st->cr();
436 MetaspaceAux::print_on(st);
437
438 if (Verbose) {
439 print_heap_regions_on(st);
440 }
441 }
442
443 class ShenandoahInitGCLABClosure : public ThreadClosure {
444 public:
445 void do_thread(Thread* thread) {
446 assert(thread == NULL || !thread->is_Java_thread(), "Don't expect JavaThread this early");
447 if (thread != NULL && thread->is_Worker_thread()) {
448 thread->gclab().initialize(true);
449 }
450 }
451 };
452
453 void ShenandoahHeap::post_initialize() {
454 if (UseTLAB) {
455 MutexLocker ml(Threads_lock);
456
457 ShenandoahInitGCLABClosure init_gclabs;
458 Threads::threads_do(&init_gclabs);
459 }
460
461 _scm->initialize(_max_workers);
462 _full_gc->initialize(_gc_timer);
463
464 ref_processing_init();
465
466 _heuristics->initialize();
467 }
468
469 size_t ShenandoahHeap::used() const {
470 OrderAccess::acquire();
471 return (size_t) _used;
472 }
473
474 size_t ShenandoahHeap::committed() const {
475 OrderAccess::acquire();
476 return _committed;
477 }
478
479 void ShenandoahHeap::increase_committed(size_t bytes) {
480 assert_heaplock_or_safepoint();
481 _committed += bytes;
482 }
483
484 void ShenandoahHeap::decrease_committed(size_t bytes) {
485 assert_heaplock_or_safepoint();
486 _committed -= bytes;
487 }
488
489 void ShenandoahHeap::increase_used(size_t bytes) {
490 Atomic::add(bytes, &_used);
491 }
492
493 void ShenandoahHeap::set_used(size_t bytes) {
494 OrderAccess::release_store_fence(&_used, bytes);
495 }
496
497 void ShenandoahHeap::decrease_used(size_t bytes) {
498 assert(used() >= bytes, "never decrease heap size by more than we've left");
499 Atomic::add(-(jlong)bytes, &_used);
500 }
501
502 void ShenandoahHeap::increase_allocated(size_t bytes) {
503 Atomic::add(bytes, &_bytes_allocated_since_gc_start);
504 }
505
506 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
507 size_t bytes = words * HeapWordSize;
508 if (!waste) {
509 increase_used(bytes);
510 }
511 increase_allocated(bytes);
512 if (ShenandoahPacing) {
513 control_thread()->pacing_notify_alloc(words);
514 if (waste) {
515 pacer()->claim_for_alloc(words, true);
516 }
517 }
518 }
519
520 size_t ShenandoahHeap::capacity() const {
521 return num_regions() * ShenandoahHeapRegion::region_size_bytes();
522 }
523
524 size_t ShenandoahHeap::max_capacity() const {
525 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
526 }
527
528 size_t ShenandoahHeap::initial_capacity() const {
529 return _initial_size;
530 }
531
532 bool ShenandoahHeap::is_in(const void* p) const {
533 HeapWord* heap_base = (HeapWord*) base();
534 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
535 return p >= heap_base && p < last_region_end;
536 }
537
538 void ShenandoahHeap::op_uncommit(double shrink_before) {
539 assert (ShenandoahUncommit, "should be enabled");
540
541 size_t count = 0;
542 for (size_t i = 0; i < num_regions(); i++) {
543 ShenandoahHeapRegion* r = get_region(i);
544 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
545 ShenandoahHeapLocker locker(lock());
546 if (r->is_empty_committed()) {
547 r->make_uncommitted();
548 count++;
549 }
550 }
551 SpinPause(); // allow allocators to take the lock
552 }
553
554 if (count > 0) {
555 log_info(gc)("Uncommitted " SIZE_FORMAT "M. Heap: " SIZE_FORMAT "M reserved, " SIZE_FORMAT "M committed, " SIZE_FORMAT "M used",
556 count * ShenandoahHeapRegion::region_size_bytes() / M, capacity() / M, committed() / M, used() / M);
557 _control_thread->notify_heap_changed();
558 }
559 }
560
561 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
562 // Retain tlab and allocate object in shared space if
563 // the amount free in the tlab is too large to discard.
564 if (thread->gclab().free() > thread->gclab().refill_waste_limit()) {
565 thread->gclab().record_slow_allocation(size);
566 return NULL;
567 }
568
569 // Discard gclab and allocate a new one.
570 // To minimize fragmentation, the last GCLAB may be smaller than the rest.
571 size_t new_gclab_size = thread->gclab().compute_size(size);
572
573 thread->gclab().clear_before_allocation();
574
575 if (new_gclab_size == 0) {
576 return NULL;
577 }
578
579 // Allocated object should fit in new GCLAB, and new_gclab_size should be larger than min
580 size_t min_size = MAX2(size + ThreadLocalAllocBuffer::alignment_reserve(), ThreadLocalAllocBuffer::min_size());
581 new_gclab_size = MAX2(new_gclab_size, min_size);
582
583 // Allocate a new GCLAB...
584 size_t actual_size = 0;
585 HeapWord* obj = allocate_new_gclab(min_size, new_gclab_size, &actual_size);
586
587 if (obj == NULL) {
588 return NULL;
589 }
590
591 assert (size <= actual_size, "allocation should fit");
592
593 if (ZeroTLAB) {
594 // ..and clear it.
595 Copy::zero_to_words(obj, actual_size);
596 } else {
597 // ...and zap just allocated object.
598 #ifdef ASSERT
599 // Skip mangling the space corresponding to the object header to
600 // ensure that the returned space is not considered parsable by
601 // any concurrent GC thread.
602 size_t hdr_size = oopDesc::header_size();
603 Copy::fill_to_words(obj + hdr_size, actual_size - hdr_size, badHeapWordVal);
604 #endif // ASSERT
605 }
606 thread->gclab().fill(obj, obj + size, actual_size);
607 return obj;
608 }
609
610 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t word_size) {
611 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(word_size);
612 return allocate_memory(req);
613 }
614
615 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
616 size_t word_size,
617 size_t* actual_size) {
618 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
619 HeapWord* res = allocate_memory(req);
620 if (res != NULL) {
621 *actual_size = req.actual_size();
622 } else {
623 *actual_size = 0;
624 }
625 return res;
626 }
627
628 ShenandoahHeap* ShenandoahHeap::heap() {
629 CollectedHeap* heap = Universe::heap();
630 assert(heap != NULL, "Unitialized access to ShenandoahHeap::heap()");
631 assert(heap->kind() == CollectedHeap::ShenandoahHeap, "not a shenandoah heap");
632 return (ShenandoahHeap*) heap;
633 }
634
635 ShenandoahHeap* ShenandoahHeap::heap_no_check() {
636 CollectedHeap* heap = Universe::heap();
637 return (ShenandoahHeap*) heap;
638 }
639
640 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
641 ShenandoahAllocTrace trace_alloc(req.size(), req.type());
642
643 intptr_t pacer_epoch = 0;
644 bool in_new_region = false;
645 HeapWord* result = NULL;
646
647 if (req.is_mutator_alloc()) {
648 if (ShenandoahPacing) {
649 pacer()->pace_for_alloc(req.size());
650 pacer_epoch = pacer()->epoch();
651 }
652
653 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
654 result = allocate_memory_under_lock(req, in_new_region);
655 }
656
657 // Allocation failed, block until control thread reacted, then retry allocation.
658 //
659 // It might happen that one of the threads requesting allocation would unblock
660 // way later after GC happened, only to fail the second allocation, because
661 // other threads have already depleted the free storage. In this case, a better
662 // strategy is to try again, as long as GC makes progress.
663 //
664 // Then, we need to make sure the allocation was retried after at least one
665 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
666
667 size_t tries = 0;
668
669 while (result == NULL && _progress_last_gc.is_set()) {
670 tries++;
671 control_thread()->handle_alloc_failure(req.size());
672 result = allocate_memory_under_lock(req, in_new_region);
673 }
674
675 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
676 tries++;
677 control_thread()->handle_alloc_failure(req.size());
678 result = allocate_memory_under_lock(req, in_new_region);
679 }
680
681 } else {
682 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
683 result = allocate_memory_under_lock(req, in_new_region);
684 // Do not call handle_alloc_failure() here, because we cannot block.
685 // The allocation failure would be handled by the WB slowpath with handle_alloc_failure_evac().
686 }
687
688 if (in_new_region) {
689 control_thread()->notify_heap_changed();
690 }
691
692 if (result != NULL) {
693 size_t requested = req.size();
694 size_t actual = req.actual_size();
695
696 assert (req.is_lab_alloc() || (requested == actual),
697 err_msg("Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
698 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual));
699
700 if (req.is_mutator_alloc()) {
701 notify_mutator_alloc_words(actual, false);
702
703 // If we requested more than we were granted, give the rest back to pacer.
704 // This only matters if we are in the same pacing epoch: do not try to unpace
705 // over the budget for the other phase.
706 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
707 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
708 }
709 } else {
710 increase_used(actual*HeapWordSize);
711 }
712 }
713
714 return result;
715 }
716
717 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
718 ShenandoahHeapLocker locker(lock());
719 return _free_set->allocate(req, in_new_region);
720 }
721
722 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
723 bool* gc_overhead_limit_was_exceeded) {
724 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size + ShenandoahBrooksPointer::word_size());
725 HeapWord* filler = allocate_memory(req);
726 HeapWord* result = filler + ShenandoahBrooksPointer::word_size();
727 if (filler != NULL) {
728 ShenandoahBrooksPointer::initialize(oop(result));
729
730 assert(! in_collection_set(result), "never allocate in targetted region");
731 return result;
732 } else {
733 return NULL;
734 }
735 }
736
737 class ShenandoahEvacuateUpdateRootsClosure: public ExtendedOopClosure {
738 private:
739 ShenandoahHeap* _heap;
740 Thread* _thread;
741 public:
742 ShenandoahEvacuateUpdateRootsClosure() :
743 _heap(ShenandoahHeap::heap()), _thread(Thread::current()) {
744 }
745
746 private:
747 template <class T>
748 void do_oop_work(T* p) {
749 assert(_heap->is_evacuation_in_progress(), "Only do this when evacuation is in progress");
750
751 T o = oopDesc::load_heap_oop(p);
752 if (! oopDesc::is_null(o)) {
753 oop obj = oopDesc::decode_heap_oop_not_null(o);
754 if (_heap->in_collection_set(obj)) {
755 shenandoah_assert_marked(p, obj);
756 oop resolved = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
757 if (oopDesc::unsafe_equals(resolved, obj)) {
758 bool evac;
759 resolved = _heap->evacuate_object(obj, _thread, evac);
760 }
761 oopDesc::encode_store_heap_oop(p, resolved);
762 }
763 }
764 }
765
766 public:
767 void do_oop(oop* p) {
768 do_oop_work(p);
769 }
770 void do_oop(narrowOop* p) {
771 do_oop_work(p);
772 }
773 };
774
775 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
776 private:
777 ShenandoahHeap* const _heap;
778 Thread* const _thread;
779 public:
780 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
781 _heap(heap), _thread(Thread::current()) {}
782
783 void do_object(oop p) {
784 shenandoah_assert_marked(NULL, p);
785 if (oopDesc::unsafe_equals(p, ShenandoahBarrierSet::resolve_forwarded_not_null(p))) {
786 bool evac;
787 _heap->evacuate_object(p, _thread, evac);
788 }
789 }
790 };
791
792 class ShenandoahEvacuationTask : public AbstractGangTask {
793 private:
794 ShenandoahHeap* const _sh;
795 ShenandoahCollectionSet* const _cs;
796 bool _concurrent;
797 public:
798 ShenandoahEvacuationTask(ShenandoahHeap* sh,
799 ShenandoahCollectionSet* cs,
800 bool concurrent) :
801 AbstractGangTask("Parallel Evacuation Task"),
802 _sh(sh),
803 _cs(cs),
804 _concurrent(concurrent)
805 {}
806
807 void work(uint worker_id) {
808 ShenandoahEvacOOMScope oom_evac_scope;
809 if (_concurrent) {
810 ShenandoahConcurrentWorkerSession worker_session(worker_id);
811 do_work();
812 } else {
813 ShenandoahParallelWorkerSession worker_session(worker_id);
814 do_work();
815 }
816 }
817
818 private:
819 void do_work() {
820 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
821 ShenandoahHeapRegion* r;
822 while ((r =_cs->claim_next()) != NULL) {
823 assert(r->has_live(), "all-garbage regions are reclaimed early");
824 _sh->marked_object_iterate(r, &cl);
825
826 if (ShenandoahPacing) {
827 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
828 }
829
830 if (_sh->cancelled_gc()) {
831 break;
832 }
833 }
834 }
835 };
836
837 void ShenandoahHeap::trash_cset_regions() {
838 ShenandoahHeapLocker locker(lock());
839
840 ShenandoahCollectionSet* set = collection_set();
841 ShenandoahHeapRegion* r;
842 set->clear_current_index();
843 while ((r = set->next()) != NULL) {
844 r->make_trash();
845 }
846 collection_set()->clear();
847 }
848
849 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
850 st->print_cr("Heap Regions:");
851 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
852 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
853 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start (previous, next)");
854
855 for (size_t i = 0; i < num_regions(); i++) {
856 get_region(i)->print_on(st);
857 }
858 }
859
860 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
861 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
862
863 oop humongous_obj = oop(start->bottom() + ShenandoahBrooksPointer::word_size());
864 size_t size = humongous_obj->size() + ShenandoahBrooksPointer::word_size();
865 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
866 size_t index = start->region_number() + required_regions - 1;
867
868 assert(!start->has_live(), "liveness must be zero");
869
870 for(size_t i = 0; i < required_regions; i++) {
871 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
872 // as it expects that every region belongs to a humongous region starting with a humongous start region.
873 ShenandoahHeapRegion* region = get_region(index --);
874
875 assert(region->is_humongous(), "expect correct humongous start or continuation");
876 assert(!region->is_cset(), "Humongous region should not be in collection set");
877
878 region->make_trash_immediate();
879 }
880 }
881
882 class ShenandoahRetireGCLABClosure : public ThreadClosure {
883 private:
884 bool _retire;
885 public:
886 ShenandoahRetireGCLABClosure(bool retire) : _retire(retire) {};
887
888 void do_thread(Thread* thread) {
889 assert(thread->gclab().is_initialized(), err_msg("GCLAB should be initialized for %s", thread->name()));
890 thread->gclab().make_parsable(_retire);
891 }
892 };
893
894 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
895 if (UseTLAB) {
896 CollectedHeap::ensure_parsability(retire_tlabs);
897 ShenandoahRetireGCLABClosure cl(retire_tlabs);
898 Threads::java_threads_do(&cl);
899 _workers->threads_do(&cl);
900 }
901 }
902
903 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
904 private:
905 ShenandoahRootEvacuator* _rp;
906
907 public:
908 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
909 AbstractGangTask("Shenandoah evacuate and update roots"),
910 _rp(rp) {}
911
912 void work(uint worker_id) {
913 ShenandoahParallelWorkerSession worker_session(worker_id);
914 ShenandoahEvacOOMScope oom_evac_scope;
915 ShenandoahEvacuateUpdateRootsClosure cl;
916
917 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
918 _rp->process_evacuate_roots(&cl, &blobsCl, worker_id);
919 }
920 };
921
922 void ShenandoahHeap::evacuate_and_update_roots() {
923 COMPILER2_PRESENT(DerivedPointerTable::clear());
924
925 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
926
927 {
928 ShenandoahRootEvacuator rp(this, workers()->active_workers(), ShenandoahPhaseTimings::init_evac);
929 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
930 workers()->run_task(&roots_task);
931 }
932
933 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
934 }
935
936 void ShenandoahHeap::roots_iterate(OopClosure* cl) {
937 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
938
939 CodeBlobToOopClosure blobsCl(cl, false);
940 CLDToOopClosure cldCl(cl);
941
942 ShenandoahRootProcessor rp(this, 1, ShenandoahPhaseTimings::_num_phases);
943 rp.process_all_roots(cl, NULL, &cldCl, &blobsCl, NULL, 0);
944 }
945
946 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
947 // Returns size in bytes
948 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
949 }
950
951 size_t ShenandoahHeap::max_tlab_size() const {
952 // Returns size in words
953 return ShenandoahHeapRegion::max_tlab_size_words();
954 }
955
956 class ShenandoahResizeGCLABClosure : public ThreadClosure {
957 public:
958 void do_thread(Thread* thread) {
959 assert(thread->gclab().is_initialized(), err_msg("GCLAB should be initialized for %s", thread->name()));
960 thread->gclab().resize();
961 }
962 };
963
964 void ShenandoahHeap::resize_all_tlabs() {
965 CollectedHeap::resize_all_tlabs();
966
967 ShenandoahResizeGCLABClosure cl;
968 Threads::java_threads_do(&cl);
969 _workers->threads_do(&cl);
970 }
971
972 class ShenandoahAccumulateStatisticsGCLABClosure : public ThreadClosure {
973 public:
974 void do_thread(Thread* thread) {
975 assert(thread->gclab().is_initialized(), err_msg("GCLAB should be initialized for %s", thread->name()));
976 thread->gclab().accumulate_statistics();
977 thread->gclab().initialize_statistics();
978 }
979 };
980
981 void ShenandoahHeap::accumulate_statistics_all_gclabs() {
982 ShenandoahAccumulateStatisticsGCLABClosure cl;
983 Threads::java_threads_do(&cl);
984 _workers->threads_do(&cl);
985 }
986
987 void ShenandoahHeap::collect(GCCause::Cause cause) {
988 _control_thread->request_gc(cause);
989 }
990
991 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
992 //assert(false, "Shouldn't need to do full collections");
993 }
994
995 CollectorPolicy* ShenandoahHeap::collector_policy() const {
996 return _shenandoah_policy;
997 }
998
999 void ShenandoahHeap::resize_tlabs() {
1000 CollectedHeap::resize_all_tlabs();
1001 }
1002
1003 void ShenandoahHeap::accumulate_statistics_tlabs() {
1004 CollectedHeap::accumulate_statistics_all_tlabs();
1005 }
1006
1007 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1008 Space* sp = heap_region_containing(addr);
1009 if (sp != NULL) {
1010 return sp->block_start(addr);
1011 }
1012 return NULL;
1013 }
1014
1015 size_t ShenandoahHeap::block_size(const HeapWord* addr) const {
1016 Space* sp = heap_region_containing(addr);
1017 assert(sp != NULL, "block_size of address outside of heap");
1018 return sp->block_size(addr);
1019 }
1020
1021 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1022 Space* sp = heap_region_containing(addr);
1023 return sp->block_is_obj(addr);
1024 }
1025
1026 jlong ShenandoahHeap::millis_since_last_gc() {
1027 double v = heuristics()->time_since_last_gc() * 1000;
1028 assert(0 <= v && v <= max_jlong, err_msg("value should fit: %f", v));
1029 return (jlong)v;
1030 }
1031
1032 void ShenandoahHeap::prepare_for_verify() {
1033 if (SafepointSynchronize::is_at_safepoint()) {
1034 make_parsable(false);
1035 }
1036 }
1037
1038 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1039 workers()->print_worker_threads_on(st);
1040 if (ShenandoahStringDedup::is_enabled()) {
1041 ShenandoahStringDedup::print_worker_threads_on(st);
1042 }
1043 }
1044
1045 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1046 workers()->threads_do(tcl);
1047 if (ShenandoahStringDedup::is_enabled()) {
1048 ShenandoahStringDedup::threads_do(tcl);
1049 }
1050 }
1051
1052 void ShenandoahHeap::print_tracing_info() const {
1053 if (PrintGC || TraceGen0Time || TraceGen1Time) {
1054 ResourceMark rm;
1055 outputStream* out = gclog_or_tty;
1056 phase_timings()->print_on(out);
1057
1058 out->cr();
1059 out->cr();
1060
1061 shenandoah_policy()->print_gc_stats(out);
1062
1063 out->cr();
1064 out->cr();
1065
1066 if (ShenandoahPacing) {
1067 pacer()->print_on(out);
1068 }
1069
1070 out->cr();
1071 out->cr();
1072
1073 if (ShenandoahAllocationTrace) {
1074 assert(alloc_tracker() != NULL, "Must be");
1075 alloc_tracker()->print_on(out);
1076 } else {
1077 out->print_cr(" Allocation tracing is disabled, use -XX:+ShenandoahAllocationTrace to enable.");
1078 }
1079 }
1080 }
1081
1082 void ShenandoahHeap::verify(bool silent, VerifyOption vo) {
1083 if (ShenandoahSafepoint::is_at_shenandoah_safepoint() || ! UseTLAB) {
1084 if (ShenandoahVerify) {
1085 verifier()->verify_generic(vo);
1086 } else {
1087 // TODO: Consider allocating verification bitmaps on demand,
1088 // and turn this on unconditionally.
1089 }
1090 }
1091 }
1092 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1093 return _free_set->capacity();
1094 }
1095
1096 class ObjectIterateScanRootClosure : public ExtendedOopClosure {
1097 private:
1098 MarkBitMap* _bitmap;
1099 Stack<oop,mtGC>* _oop_stack;
1100
1101 template <class T>
1102 void do_oop_work(T* p) {
1103 T o = oopDesc::load_heap_oop(p);
1104 if (!oopDesc::is_null(o)) {
1105 oop obj = oopDesc::decode_heap_oop_not_null(o);
1106 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1107 assert(obj->is_oop(), "must be a valid oop");
1108 if (!_bitmap->isMarked((HeapWord*) obj)) {
1109 _bitmap->mark((HeapWord*) obj);
1110 _oop_stack->push(obj);
1111 }
1112 }
1113 }
1114 public:
1115 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1116 _bitmap(bitmap), _oop_stack(oop_stack) {}
1117 void do_oop(oop* p) { do_oop_work(p); }
1118 void do_oop(narrowOop* p) { do_oop_work(p); }
1119 };
1120
1121 /*
1122 * This is public API, used in preparation of object_iterate().
1123 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1124 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1125 * control, we call SH::make_parsable().
1126 */
1127 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1128 // No-op.
1129 }
1130
1131 /*
1132 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1133 *
1134 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1135 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1136 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1137 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1138 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1139 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1140 * wiped the bitmap in preparation for next marking).
1141 *
1142 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1143 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1144 * is allowed to report dead objects, but is not required to do so.
1145 */
1146 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1147 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1148 if (!os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1149 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1150 return;
1151 }
1152
1153 // Reset bitmap
1154 _aux_bit_map.clear();
1155
1156 Stack<oop,mtGC> oop_stack;
1157
1158 // First, we process all GC roots. This populates the work stack with initial objects.
1159 ShenandoahRootProcessor rp(this, 1, ShenandoahPhaseTimings::_num_phases);
1160 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1161 CLDToOopClosure clds(&oops, false);
1162 CodeBlobToOopClosure blobs(&oops, false);
1163 rp.process_all_roots(&oops, &oops, &clds, &blobs, NULL, 0);
1164
1165 // Work through the oop stack to traverse heap.
1166 while (! oop_stack.is_empty()) {
1167 oop obj = oop_stack.pop();
1168 assert(obj->is_oop(), "must be a valid oop");
1169 cl->do_object(obj);
1170 obj->oop_iterate(&oops);
1171 }
1172
1173 assert(oop_stack.is_empty(), "should be empty");
1174
1175 if (!os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1176 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1177 }
1178 }
1179
1180 void ShenandoahHeap::safe_object_iterate(ObjectClosure* cl) {
1181 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1182 object_iterate(cl);
1183 }
1184
1185 void ShenandoahHeap::oop_iterate(ExtendedOopClosure* cl) {
1186 ObjectToOopClosure cl2(cl);
1187 object_iterate(&cl2);
1188 }
1189
1190 class ShenandoahSpaceClosureRegionClosure: public ShenandoahHeapRegionClosure {
1191 SpaceClosure* _cl;
1192 public:
1193 ShenandoahSpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
1194 void heap_region_do(ShenandoahHeapRegion* r) {
1195 _cl->do_space(r);
1196 }
1197 };
1198
1199 void ShenandoahHeap::space_iterate(SpaceClosure* cl) {
1200 ShenandoahSpaceClosureRegionClosure blk(cl);
1201 heap_region_iterate(&blk);
1202 }
1203
1204 Space* ShenandoahHeap::space_containing(const void* oop) const {
1205 Space* res = heap_region_containing(oop);
1206 return res;
1207 }
1208
1209 void ShenandoahHeap::gc_prologue(bool b) {
1210 Unimplemented();
1211 }
1212
1213 void ShenandoahHeap::gc_epilogue(bool b) {
1214 Unimplemented();
1215 }
1216
1217 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1218 for (size_t i = 0; i < num_regions(); i++) {
1219 ShenandoahHeapRegion* current = get_region(i);
1220 blk->heap_region_do(current);
1221 }
1222 }
1223
1224 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1225 private:
1226 ShenandoahHeap* const _heap;
1227 ShenandoahHeapRegionClosure* const _blk;
1228
1229 char _pad0[DEFAULT_CACHE_LINE_SIZE];
1230 volatile jint _index;
1231 char _pad1[DEFAULT_CACHE_LINE_SIZE];
1232
1233 public:
1234 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1235 AbstractGangTask("Parallel Region Task"),
1236 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1237
1238 void work(uint worker_id) {
1239 jint stride = (jint)ShenandoahParallelRegionStride;
1240
1241 jint max = (jint)_heap->num_regions();
1242 while (_index < max) {
1243 jint cur = Atomic::add(stride, &_index) - stride;
1244 jint start = cur;
1245 jint end = MIN2(cur + stride, max);
1246 if (start >= max) break;
1247
1248 for (jint i = cur; i < end; i++) {
1249 ShenandoahHeapRegion* current = _heap->get_region((size_t)i);
1250 _blk->heap_region_do(current);
1251 }
1252 }
1253 }
1254 };
1255
1256 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1257 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1258 if (num_regions() > ShenandoahParallelRegionStride) {
1259 ShenandoahParallelHeapRegionTask task(blk);
1260 workers()->run_task(&task);
1261 } else {
1262 heap_region_iterate(blk);
1263 }
1264 }
1265
1266 class ShenandoahClearLivenessClosure : public ShenandoahHeapRegionClosure {
1267 private:
1268 ShenandoahMarkingContext* const _ctx;
1269 public:
1270 ShenandoahClearLivenessClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1271
1272 void heap_region_do(ShenandoahHeapRegion* r) {
1273 if (r->is_active()) {
1274 r->clear_live_data();
1275 _ctx->capture_top_at_mark_start(r);
1276 } else {
1277 assert(!r->has_live(),
1278 err_msg("Region " SIZE_FORMAT " should have no live data", r->region_number()));
1279 assert(_ctx->top_at_mark_start(r) == r->top(),
1280 err_msg("Region " SIZE_FORMAT " should already have correct TAMS", r->region_number()));
1281 }
1282 }
1283
1284 bool is_thread_safe() { return true; }
1285 };
1286
1287 void ShenandoahHeap::op_init_mark() {
1288 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1289 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1290
1291 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1292 assert(!marking_context()->is_complete(), "should not be complete");
1293
1294 if (ShenandoahVerify) {
1295 verifier()->verify_before_concmark();
1296 }
1297
1298 {
1299 ShenandoahGCPhase phase(ShenandoahPhaseTimings::accumulate_stats);
1300 accumulate_statistics_tlabs();
1301 }
1302
1303 if (VerifyBeforeGC) {
1304 Universe::verify();
1305 }
1306
1307 set_concurrent_mark_in_progress(true);
1308 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1309 if (UseTLAB) {
1310 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1311 make_parsable(true);
1312 }
1313
1314 {
1315 ShenandoahGCPhase phase(ShenandoahPhaseTimings::clear_liveness);
1316 ShenandoahClearLivenessClosure clc;
1317 parallel_heap_region_iterate(&clc);
1318 }
1319
1320 // Make above changes visible to worker threads
1321 OrderAccess::fence();
1322
1323 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1324
1325 if (UseTLAB) {
1326 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1327 resize_tlabs();
1328 }
1329
1330 if (ShenandoahPacing) {
1331 pacer()->setup_for_mark();
1332 }
1333 }
1334
1335 void ShenandoahHeap::op_mark() {
1336 concurrent_mark()->mark_from_roots();
1337 }
1338
1339 class ShenandoahCompleteLivenessClosure : public ShenandoahHeapRegionClosure {
1340 private:
1341 ShenandoahMarkingContext* const _ctx;
1342 public:
1343 ShenandoahCompleteLivenessClosure() : _ctx(ShenandoahHeap::heap()->complete_marking_context()) {}
1344
1345 void heap_region_do(ShenandoahHeapRegion* r) {
1346 if (r->is_active()) {
1347 HeapWord *tams = _ctx->top_at_mark_start(r);
1348 HeapWord *top = r->top();
1349 if (top > tams) {
1350 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1351 }
1352 } else {
1353 assert(!r->has_live(),
1354 err_msg("Region " SIZE_FORMAT " should have no live data", r->region_number()));
1355 assert(_ctx->top_at_mark_start(r) == r->top(),
1356 err_msg("Region " SIZE_FORMAT " should have correct TAMS", r->region_number()));
1357 }
1358 }
1359
1360 bool is_thread_safe() { return true; }
1361 };
1362
1363 void ShenandoahHeap::op_final_mark() {
1364 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1365
1366 // It is critical that we
1367 // evacuate roots right after finishing marking, so that we don't
1368 // get unmarked objects in the roots.
1369
1370 if (!cancelled_gc()) {
1371 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1372
1373 TASKQUEUE_STATS_ONLY(concurrent_mark()->task_queues()->reset_taskqueue_stats());
1374
1375 if (has_forwarded_objects()) {
1376 concurrent_mark()->update_roots(ShenandoahPhaseTimings::update_roots);
1377 }
1378
1379 TASKQUEUE_STATS_ONLY(concurrent_mark()->task_queues()->print_taskqueue_stats());
1380
1381 stop_concurrent_marking();
1382
1383 {
1384 ShenandoahGCPhase phase(ShenandoahPhaseTimings::complete_liveness);
1385
1386 // All allocations past TAMS are implicitly live, adjust the region data.
1387 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1388 ShenandoahCompleteLivenessClosure cl;
1389 parallel_heap_region_iterate(&cl);
1390 }
1391
1392 {
1393 ShenandoahGCPhase prepare_evac(ShenandoahPhaseTimings::prepare_evac);
1394
1395 make_parsable(true);
1396
1397 trash_cset_regions();
1398
1399 {
1400 ShenandoahHeapLocker locker(lock());
1401 _collection_set->clear();
1402 _free_set->clear();
1403
1404 heuristics()->choose_collection_set(_collection_set);
1405 _free_set->rebuild();
1406 }
1407 }
1408
1409 // If collection set has candidates, start evacuation.
1410 // Otherwise, bypass the rest of the cycle.
1411 if (!collection_set()->is_empty()) {
1412 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1413
1414 if (ShenandoahVerify) {
1415 verifier()->verify_before_evacuation();
1416 }
1417
1418 set_evacuation_in_progress(true);
1419 // From here on, we need to update references.
1420 set_has_forwarded_objects(true);
1421
1422 evacuate_and_update_roots();
1423
1424 if (ShenandoahPacing) {
1425 pacer()->setup_for_evac();
1426 }
1427 } else {
1428 if (ShenandoahVerify) {
1429 verifier()->verify_after_concmark();
1430 }
1431
1432 if (VerifyAfterGC) {
1433 Universe::verify();
1434 }
1435 }
1436
1437 } else {
1438 concurrent_mark()->cancel();
1439 stop_concurrent_marking();
1440
1441 if (process_references()) {
1442 // Abandon reference processing right away: pre-cleaning must have failed.
1443 ReferenceProcessor *rp = ref_processor();
1444 rp->disable_discovery();
1445 rp->abandon_partial_discovery();
1446 rp->verify_no_references_recorded();
1447 }
1448 }
1449 }
1450
1451 void ShenandoahHeap::op_final_evac() {
1452 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1453
1454 set_evacuation_in_progress(false);
1455 if (ShenandoahVerify) {
1456 verifier()->verify_after_evacuation();
1457 }
1458
1459 if (VerifyAfterGC) {
1460 Universe::verify();
1461 }
1462 }
1463
1464 void ShenandoahHeap::op_conc_evac() {
1465 ShenandoahEvacuationTask task(this, _collection_set, true);
1466 workers()->run_task(&task);
1467 }
1468
1469 void ShenandoahHeap::op_stw_evac() {
1470 ShenandoahEvacuationTask task(this, _collection_set, false);
1471 workers()->run_task(&task);
1472 }
1473
1474 void ShenandoahHeap::op_updaterefs() {
1475 update_heap_references(true);
1476 }
1477
1478 void ShenandoahHeap::op_cleanup() {
1479 free_set()->recycle_trash();
1480 }
1481
1482 void ShenandoahHeap::op_reset() {
1483 reset_mark_bitmap();
1484 }
1485
1486 void ShenandoahHeap::op_preclean() {
1487 concurrent_mark()->preclean_weak_refs();
1488 }
1489
1490 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1491 ShenandoahMetricsSnapshot metrics;
1492 metrics.snap_before();
1493
1494 full_gc()->do_it(cause);
1495
1496 metrics.snap_after();
1497 metrics.print();
1498
1499 if (metrics.is_good_progress("Full GC")) {
1500 _progress_last_gc.set();
1501 } else {
1502 // Nothing to do. Tell the allocation path that we have failed to make
1503 // progress, and it can finally fail.
1504 _progress_last_gc.unset();
1505 }
1506 }
1507
1508 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1509 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1510 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1511 // some phase, we have to upgrade the Degenerate GC to Full GC.
1512
1513 clear_cancelled_gc();
1514
1515 ShenandoahMetricsSnapshot metrics;
1516 metrics.snap_before();
1517
1518 switch (point) {
1519 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1520 // but enters it at different points, depending on which concurrent phase had
1521 // degenerated.
1522
1523 case _degenerated_outside_cycle:
1524 // We have degenerated from outside the cycle, which means something is bad with
1525 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1526 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1527 // we can do the most aggressive degen cycle, which includes processing references and
1528 // class unloading, unless those features are explicitly disabled.
1529 //
1530 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1531 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1532 set_process_references(heuristics()->can_process_references());
1533 set_unload_classes(heuristics()->can_unload_classes());
1534
1535 op_reset();
1536
1537 op_init_mark();
1538 if (cancelled_gc()) {
1539 op_degenerated_fail();
1540 return;
1541 }
1542
1543 case _degenerated_mark:
1544 op_final_mark();
1545 if (cancelled_gc()) {
1546 op_degenerated_fail();
1547 return;
1548 }
1549
1550 op_cleanup();
1551
1552 case _degenerated_evac:
1553 // If heuristics thinks we should do the cycle, this flag would be set,
1554 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
1555 if (is_evacuation_in_progress()) {
1556
1557 // Degeneration under oom-evac protocol might have left some objects in
1558 // collection set un-evacuated. Restart evacuation from the beginning to
1559 // capture all objects. For all the objects that are already evacuated,
1560 // it would be a simple check, which is supposed to be fast. This is also
1561 // safe to do even without degeneration, as CSet iterator is at beginning
1562 // in preparation for evacuation anyway.
1563 collection_set()->clear_current_index();
1564
1565 op_stw_evac();
1566 if (cancelled_gc()) {
1567 op_degenerated_fail();
1568 return;
1569 }
1570 }
1571
1572 // If heuristics thinks we should do the cycle, this flag would be set,
1573 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
1574 if (has_forwarded_objects()) {
1575 op_init_updaterefs();
1576 if (cancelled_gc()) {
1577 op_degenerated_fail();
1578 return;
1579 }
1580 }
1581
1582 case _degenerated_updaterefs:
1583 if (has_forwarded_objects()) {
1584 op_final_updaterefs();
1585 if (cancelled_gc()) {
1586 op_degenerated_fail();
1587 return;
1588 }
1589 }
1590
1591 op_cleanup();
1592 break;
1593
1594 default:
1595 ShouldNotReachHere();
1596 }
1597
1598 if (ShenandoahVerify) {
1599 verifier()->verify_after_degenerated();
1600 }
1601
1602 if (VerifyAfterGC) {
1603 Universe::verify();
1604 }
1605
1606 metrics.snap_after();
1607 metrics.print();
1608
1609 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
1610 // because that probably means the heap is overloaded and/or fragmented.
1611 if (!metrics.is_good_progress("Degenerated GC")) {
1612 _progress_last_gc.unset();
1613 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1614 op_degenerated_futile();
1615 } else {
1616 _progress_last_gc.set();
1617 }
1618 }
1619
1620 void ShenandoahHeap::op_degenerated_fail() {
1621 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
1622 shenandoah_policy()->record_degenerated_upgrade_to_full();
1623 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1624 }
1625
1626 void ShenandoahHeap::op_degenerated_futile() {
1627 shenandoah_policy()->record_degenerated_upgrade_to_full();
1628 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1629 }
1630
1631 void ShenandoahHeap::stop_concurrent_marking() {
1632 assert(is_concurrent_mark_in_progress(), "How else could we get here?");
1633 if (!cancelled_gc()) {
1634 // If we needed to update refs, and concurrent marking has been cancelled,
1635 // we need to finish updating references.
1636 set_has_forwarded_objects(false);
1637 mark_complete_marking_context();
1638 }
1639 set_concurrent_mark_in_progress(false);
1640 }
1641
1642 void ShenandoahHeap::force_satb_flush_all_threads() {
1643 if (!is_concurrent_mark_in_progress()) {
1644 // No need to flush SATBs
1645 return;
1646 }
1647
1648 // Do not block if Threads lock is busy. This avoids the potential deadlock
1649 // when this code is called from the periodic task, and something else is
1650 // expecting the periodic task to complete without blocking. On the off-chance
1651 // Threads lock is busy momentarily, try to acquire several times.
1652 for (int t = 0; t < 10; t++) {
1653 if (Threads_lock->try_lock()) {
1654 JavaThread::set_force_satb_flush_all_threads(true);
1655 Threads_lock->unlock();
1656
1657 // The threads are not "acquiring" their thread-local data, but it does not
1658 // hurt to "release" the updates here anyway.
1659 OrderAccess::fence();
1660 break;
1661 }
1662 os::naked_short_sleep(1);
1663 }
1664 }
1665
1666 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1667 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1668 _gc_state.set_cond(mask, value);
1669 JavaThread::set_gc_state_all_threads(_gc_state.raw_value());
1670 }
1671
1672 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1673 set_gc_state_mask(MARKING, in_progress);
1674 JavaThread::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1675 }
1676
1677 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1678 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1679 set_gc_state_mask(EVACUATION, in_progress);
1680 }
1681
1682 HeapWord* ShenandoahHeap::tlab_post_allocation_setup(HeapWord* obj) {
1683 // Initialize Brooks pointer for the next object
1684 HeapWord* result = obj + ShenandoahBrooksPointer::word_size();
1685 ShenandoahBrooksPointer::initialize(oop(result));
1686 return result;
1687 }
1688
1689 uint ShenandoahHeap::oop_extra_words() {
1690 return ShenandoahBrooksPointer::word_size();
1691 }
1692
1693 ShenandoahForwardedIsAliveClosure::ShenandoahForwardedIsAliveClosure() :
1694 _mark_context(ShenandoahHeap::heap()->marking_context()) {
1695 }
1696
1697 ShenandoahIsAliveClosure::ShenandoahIsAliveClosure() :
1698 _mark_context(ShenandoahHeap::heap()->marking_context()) {
1699 }
1700
1701 bool ShenandoahForwardedIsAliveClosure::do_object_b(oop obj) {
1702 if (oopDesc::is_null(obj)) {
1703 return false;
1704 }
1705 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1706 shenandoah_assert_not_forwarded_if(NULL, obj, ShenandoahHeap::heap()->is_concurrent_mark_in_progress());
1707 return _mark_context->is_marked(obj);
1708 }
1709
1710 bool ShenandoahIsAliveClosure::do_object_b(oop obj) {
1711 if (oopDesc::is_null(obj)) {
1712 return false;
1713 }
1714 shenandoah_assert_not_forwarded(NULL, obj);
1715 return _mark_context->is_marked(obj);
1716 }
1717
1718 void ShenandoahHeap::ref_processing_init() {
1719 MemRegion mr = reserved_region();
1720
1721 assert(_max_workers > 0, "Sanity");
1722
1723 _ref_processor =
1724 new ReferenceProcessor(mr, // span
1725 ParallelRefProcEnabled, // MT processing
1726 _max_workers, // Degree of MT processing
1727 true, // MT discovery
1728 _max_workers, // Degree of MT discovery
1729 false, // Reference discovery is not atomic
1730 NULL); // No closure, should be installed before use
1731
1732 shenandoah_assert_rp_isalive_not_installed();
1733 }
1734
1735 void ShenandoahHeap::acquire_pending_refs_lock() {
1736 _control_thread->slt()->manipulatePLL(SurrogateLockerThread::acquirePLL);
1737 }
1738
1739 void ShenandoahHeap::release_pending_refs_lock() {
1740 _control_thread->slt()->manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL);
1741 }
1742
1743 GCTracer* ShenandoahHeap::tracer() {
1744 return shenandoah_policy()->tracer();
1745 }
1746
1747 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1748 return _free_set->used();
1749 }
1750
1751 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1752 if (try_cancel_gc()) {
1753 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1754 log_info(gc)("%s", msg.buffer());
1755 Events::log(Thread::current(), "%s", msg.buffer());
1756 }
1757 }
1758
1759 uint ShenandoahHeap::max_workers() {
1760 return _max_workers;
1761 }
1762
1763 void ShenandoahHeap::stop() {
1764 // The shutdown sequence should be able to terminate when GC is running.
1765
1766 // Step 0. Notify policy to disable event recording.
1767 _shenandoah_policy->record_shutdown();
1768
1769 // Step 1. Notify control thread that we are in shutdown.
1770 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1771 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1772 _control_thread->prepare_for_graceful_shutdown();
1773
1774 // Step 2. Notify GC workers that we are cancelling GC.
1775 cancel_gc(GCCause::_shenandoah_stop_vm);
1776
1777 // Step 3. Wait until GC worker exits normally.
1778 _control_thread->stop();
1779
1780 // Step 4. Stop String Dedup thread if it is active
1781 if (ShenandoahStringDedup::is_enabled()) {
1782 ShenandoahStringDedup::stop();
1783 }
1784 }
1785
1786 void ShenandoahHeap::unload_classes_and_cleanup_tables(bool full_gc) {
1787 assert(heuristics()->can_unload_classes(), "Class unloading should be enabled");
1788
1789 ShenandoahGCPhase root_phase(full_gc ?
1790 ShenandoahPhaseTimings::full_gc_purge :
1791 ShenandoahPhaseTimings::purge);
1792
1793 ShenandoahIsAliveSelector alive;
1794 BoolObjectClosure* is_alive = alive.is_alive_closure();
1795
1796 bool purged_class;
1797
1798 // Unload classes and purge SystemDictionary.
1799 {
1800 ShenandoahGCPhase phase(full_gc ?
1801 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1802 ShenandoahPhaseTimings::purge_class_unload);
1803 purged_class = SystemDictionary::do_unloading(is_alive,
1804 full_gc /* do_cleaning*/ );
1805 }
1806
1807 {
1808 ShenandoahGCPhase phase(full_gc ?
1809 ShenandoahPhaseTimings::full_gc_purge_par :
1810 ShenandoahPhaseTimings::purge_par);
1811 uint active = _workers->active_workers();
1812 ParallelCleaningTask unlink_task(is_alive, true, true, active, purged_class);
1813 _workers->run_task(&unlink_task);
1814 }
1815
1816 if (ShenandoahStringDedup::is_enabled()) {
1817 ShenandoahGCPhase phase(full_gc ?
1818 ShenandoahPhaseTimings::full_gc_purge_string_dedup :
1819 ShenandoahPhaseTimings::purge_string_dedup);
1820 ShenandoahStringDedup::parallel_cleanup();
1821 }
1822
1823 {
1824 ShenandoahGCPhase phase(full_gc ?
1825 ShenandoahPhaseTimings::full_gc_purge_cldg :
1826 ShenandoahPhaseTimings::purge_cldg);
1827 ClassLoaderDataGraph::purge();
1828 }
1829 }
1830
1831 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
1832 set_gc_state_mask(HAS_FORWARDED, cond);
1833 }
1834
1835 void ShenandoahHeap::set_process_references(bool pr) {
1836 _process_references.set_cond(pr);
1837 }
1838
1839 void ShenandoahHeap::set_unload_classes(bool uc) {
1840 _unload_classes.set_cond(uc);
1841 }
1842
1843 bool ShenandoahHeap::process_references() const {
1844 return _process_references.is_set();
1845 }
1846
1847 bool ShenandoahHeap::unload_classes() const {
1848 return _unload_classes.is_set();
1849 }
1850
1851 address ShenandoahHeap::in_cset_fast_test_addr() {
1852 ShenandoahHeap* heap = ShenandoahHeap::heap();
1853 assert(heap->collection_set() != NULL, "Sanity");
1854 return (address) heap->collection_set()->biased_map_address();
1855 }
1856
1857 address ShenandoahHeap::cancelled_gc_addr() {
1858 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
1859 }
1860
1861 address ShenandoahHeap::gc_state_addr() {
1862 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
1863 }
1864
1865 size_t ShenandoahHeap::conservative_max_heap_alignment() {
1866 size_t align = ShenandoahMaxRegionSize;
1867 if (UseLargePages) {
1868 align = MAX2(align, os::large_page_size());
1869 }
1870 return align;
1871 }
1872
1873 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
1874 return OrderAccess::load_acquire(&_bytes_allocated_since_gc_start);
1875 }
1876
1877 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
1878 OrderAccess::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
1879 }
1880
1881 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
1882 _degenerated_gc_in_progress.set_cond(in_progress);
1883 }
1884
1885 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
1886 _full_gc_in_progress.set_cond(in_progress);
1887 }
1888
1889 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
1890 assert (is_full_gc_in_progress(), "should be");
1891 _full_gc_move_in_progress.set_cond(in_progress);
1892 }
1893
1894 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
1895 set_gc_state_mask(UPDATEREFS, in_progress);
1896 }
1897
1898 void ShenandoahHeap::register_nmethod(nmethod* nm) {
1899 ShenandoahCodeRoots::add_nmethod(nm);
1900 }
1901
1902 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
1903 ShenandoahCodeRoots::remove_nmethod(nm);
1904 }
1905
1906 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
1907 o = barrier_set()->write_barrier(o);
1908 ShenandoahHeapLocker locker(lock());
1909 heap_region_containing(o)->make_pinned();
1910 return o;
1911 }
1912
1913 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
1914 o = barrier_set()->read_barrier(o);
1915 ShenandoahHeapLocker locker(lock());
1916 heap_region_containing(o)->make_unpinned();
1917 }
1918
1919 GCTimer* ShenandoahHeap::gc_timer() const {
1920 return _gc_timer;
1921 }
1922
1923 #ifdef ASSERT
1924 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
1925 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
1926
1927 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1928 if (UseDynamicNumberOfGCThreads ||
1929 (FLAG_IS_DEFAULT(ParallelGCThreads) && ForceDynamicNumberOfGCThreads)) {
1930 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
1931 } else {
1932 // Use ParallelGCThreads inside safepoints
1933 assert(nworkers == ParallelGCThreads, "Use ParalleGCThreads within safepoints");
1934 }
1935 } else {
1936 if (UseDynamicNumberOfGCThreads ||
1937 (FLAG_IS_DEFAULT(ConcGCThreads) && ForceDynamicNumberOfGCThreads)) {
1938 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
1939 } else {
1940 // Use ConcGCThreads outside safepoints
1941 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
1942 }
1943 }
1944 }
1945 #endif
1946
1947 ShenandoahVerifier* ShenandoahHeap::verifier() {
1948 guarantee(ShenandoahVerify, "Should be enabled");
1949 assert (_verifier != NULL, "sanity");
1950 return _verifier;
1951 }
1952
1953 ShenandoahUpdateHeapRefsClosure::ShenandoahUpdateHeapRefsClosure() :
1954 _heap(ShenandoahHeap::heap()) {}
1955
1956 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
1957 private:
1958 ShenandoahHeap* _heap;
1959 ShenandoahRegionIterator* _regions;
1960 bool _concurrent;
1961
1962 public:
1963 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
1964 AbstractGangTask("Concurrent Update References Task"),
1965 _heap(ShenandoahHeap::heap()),
1966 _regions(regions),
1967 _concurrent(concurrent) {
1968 }
1969
1970 void work(uint worker_id) {
1971 ShenandoahConcurrentWorkerSession worker_session(worker_id);
1972 ShenandoahUpdateHeapRefsClosure cl;
1973 ShenandoahHeapRegion* r = _regions->next();
1974 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
1975 while (r != NULL) {
1976 HeapWord* top_at_start_ur = r->concurrent_iteration_safe_limit();
1977 assert (top_at_start_ur >= r->bottom(), "sanity");
1978 if (r->is_active() && !r->is_cset()) {
1979 _heap->marked_object_oop_iterate(r, &cl, top_at_start_ur);
1980 }
1981 if (ShenandoahPacing) {
1982 _heap->pacer()->report_updaterefs(pointer_delta(top_at_start_ur, r->bottom()));
1983 }
1984 if (_heap->cancelled_gc()) {
1985 return;
1986 }
1987 r = _regions->next();
1988 }
1989 }
1990 };
1991
1992 void ShenandoahHeap::update_heap_references(bool concurrent) {
1993 ShenandoahUpdateHeapRefsTask task(&_update_refs_iterator, concurrent);
1994 workers()->run_task(&task);
1995 }
1996
1997 void ShenandoahHeap::op_init_updaterefs() {
1998 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1999
2000 set_evacuation_in_progress(false);
2001
2002 if (ShenandoahVerify) {
2003 verifier()->verify_before_updaterefs();
2004 }
2005
2006 set_update_refs_in_progress(true);
2007 make_parsable(true);
2008 for (uint i = 0; i < num_regions(); i++) {
2009 ShenandoahHeapRegion* r = get_region(i);
2010 r->set_concurrent_iteration_safe_limit(r->top());
2011 }
2012
2013 // Reset iterator.
2014 _update_refs_iterator.reset();
2015
2016 if (ShenandoahPacing) {
2017 pacer()->setup_for_updaterefs();
2018 }
2019 }
2020
2021 void ShenandoahHeap::op_final_updaterefs() {
2022 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2023
2024 // Check if there is left-over work, and finish it
2025 if (_update_refs_iterator.has_next()) {
2026 ShenandoahGCPhase final_work(ShenandoahPhaseTimings::final_update_refs_finish_work);
2027
2028 // Finish updating references where we left off.
2029 clear_cancelled_gc();
2030 update_heap_references(false);
2031 }
2032
2033 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2034 // everything. On degenerated paths, cancelled gc would not be set anyway.
2035 if (cancelled_gc()) {
2036 clear_cancelled_gc();
2037 }
2038 assert(!cancelled_gc(), "Should have been done right before");
2039
2040 concurrent_mark()->update_roots(is_degenerated_gc_in_progress() ?
2041 ShenandoahPhaseTimings::degen_gc_update_roots:
2042 ShenandoahPhaseTimings::final_update_refs_roots);
2043
2044 ShenandoahGCPhase final_update_refs(ShenandoahPhaseTimings::final_update_refs_recycle);
2045
2046 trash_cset_regions();
2047 set_has_forwarded_objects(false);
2048 set_update_refs_in_progress(false);
2049
2050 if (ShenandoahVerify) {
2051 verifier()->verify_after_updaterefs();
2052 }
2053
2054 if (VerifyAfterGC) {
2055 Universe::verify();
2056 }
2057
2058 {
2059 ShenandoahHeapLocker locker(lock());
2060 _free_set->rebuild();
2061 }
2062 }
2063
2064 #ifdef ASSERT
2065 void ShenandoahHeap::assert_heaplock_not_owned_by_current_thread() {
2066 _lock.assert_not_owned_by_current_thread();
2067 }
2068
2069 void ShenandoahHeap::assert_heaplock_owned_by_current_thread() {
2070 _lock.assert_owned_by_current_thread();
2071 }
2072
2073 void ShenandoahHeap::assert_heaplock_or_safepoint() {
2074 _lock.assert_owned_by_current_thread_or_safepoint();
2075 }
2076 #endif
2077
2078 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2079 print_on(st);
2080 print_heap_regions_on(st);
2081 }
2082
2083 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2084 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2085
2086 size_t regions_from = _bitmap_regions_per_slice * slice;
2087 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2088 for (size_t g = regions_from; g < regions_to; g++) {
2089 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2090 if (skip_self && g == r->region_number()) continue;
2091 if (get_region(g)->is_committed()) {
2092 return true;
2093 }
2094 }
2095 return false;
2096 }
2097
2098 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2099 assert_heaplock_owned_by_current_thread();
2100
2101 if (is_bitmap_slice_committed(r, true)) {
2102 // Some other region from the group is already committed, meaning the bitmap
2103 // slice is already committed, we exit right away.
2104 return true;
2105 }
2106
2107 // Commit the bitmap slice:
2108 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2109 size_t off = _bitmap_bytes_per_slice * slice;
2110 size_t len = _bitmap_bytes_per_slice;
2111 if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) {
2112 return false;
2113 }
2114 return true;
2115 }
2116
2117 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2118 assert_heaplock_owned_by_current_thread();
2119
2120 if (is_bitmap_slice_committed(r, true)) {
2121 // Some other region from the group is still committed, meaning the bitmap
2122 // slice is should stay committed, exit right away.
2123 return true;
2124 }
2125
2126 // Uncommit the bitmap slice:
2127 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2128 size_t off = _bitmap_bytes_per_slice * slice;
2129 size_t len = _bitmap_bytes_per_slice;
2130 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2131 return false;
2132 }
2133 return true;
2134 }
2135
2136 void ShenandoahHeap::vmop_entry_init_mark() {
2137 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2138 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2139 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
2140
2141 try_inject_alloc_failure();
2142 VM_ShenandoahInitMark op;
2143 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2144 }
2145
2146 void ShenandoahHeap::vmop_entry_final_mark() {
2147 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2148 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2149 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
2150
2151 try_inject_alloc_failure();
2152 VM_ShenandoahFinalMarkStartEvac op;
2153 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2154 }
2155
2156 void ShenandoahHeap::vmop_entry_final_evac() {
2157 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2158 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2159 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_gross);
2160
2161 VM_ShenandoahFinalEvac op;
2162 VMThread::execute(&op); // jump to entry_final_evac under safepoint
2163 }
2164
2165 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2166 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2167 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2168 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
2169
2170 try_inject_alloc_failure();
2171 VM_ShenandoahInitUpdateRefs op;
2172 VMThread::execute(&op);
2173 }
2174
2175 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2176 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2177 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2178 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
2179
2180 try_inject_alloc_failure();
2181 VM_ShenandoahFinalUpdateRefs op;
2182 VMThread::execute(&op);
2183 }
2184
2185 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2186 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2187 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2188 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
2189
2190 try_inject_alloc_failure();
2191 VM_ShenandoahFullGC op(cause);
2192 VMThread::execute(&op);
2193 }
2194
2195 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2196 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2197 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2198 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
2199
2200 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2201 VMThread::execute(°enerated_gc);
2202 }
2203
2204 void ShenandoahHeap::entry_init_mark() {
2205 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2206 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
2207
2208 const char* msg = init_mark_event_message();
2209 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2210 EventMark em("%s", msg);
2211
2212 ShenandoahWorkerScope scope(workers(),
2213 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2214 "init marking");
2215
2216 op_init_mark();
2217 }
2218
2219 void ShenandoahHeap::entry_final_mark() {
2220 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2221 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
2222
2223 const char* msg = final_mark_event_message();
2224 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2225 EventMark em("%s", msg);
2226
2227 ShenandoahWorkerScope scope(workers(),
2228 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2229 "final marking");
2230
2231 op_final_mark();
2232 }
2233
2234 void ShenandoahHeap::entry_final_evac() {
2235 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2236 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac);
2237
2238 const char* msg = "Pause Final Evac";
2239 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2240 EventMark em("%s", msg);
2241
2242 op_final_evac();
2243 }
2244
2245 void ShenandoahHeap::entry_init_updaterefs() {
2246 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2247 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
2248
2249 static const char* msg = "Pause Init Update Refs";
2250 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2251 EventMark em("%s", msg);
2252
2253 // No workers used in this phase, no setup required
2254
2255 op_init_updaterefs();
2256 }
2257
2258 void ShenandoahHeap::entry_final_updaterefs() {
2259 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2260 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
2261
2262 static const char* msg = "Pause Final Update Refs";
2263 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2264 EventMark em("%s", msg);
2265
2266 ShenandoahWorkerScope scope(workers(),
2267 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2268 "final reference update");
2269
2270 op_final_updaterefs();
2271 }
2272
2273 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2274 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2275 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
2276
2277 static const char* msg = "Pause Full";
2278 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id(), true);
2279 EventMark em("%s", msg);
2280
2281 ShenandoahWorkerScope scope(workers(),
2282 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2283 "full gc");
2284
2285 op_full(cause);
2286 }
2287
2288 void ShenandoahHeap::entry_degenerated(int point) {
2289 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2290 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
2291
2292 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2293 const char* msg = degen_event_message(dpoint);
2294 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id(), true);
2295 EventMark em("%s", msg);
2296
2297 ShenandoahWorkerScope scope(workers(),
2298 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2299 "stw degenerated gc");
2300
2301 set_degenerated_gc_in_progress(true);
2302 op_degenerated(dpoint);
2303 set_degenerated_gc_in_progress(false);
2304 }
2305
2306 void ShenandoahHeap::entry_mark() {
2307 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2308
2309 const char* msg = conc_mark_event_message();
2310 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2311 EventMark em("%s", msg);
2312
2313 ShenandoahWorkerScope scope(workers(),
2314 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2315 "concurrent marking");
2316
2317 try_inject_alloc_failure();
2318 op_mark();
2319 }
2320
2321 void ShenandoahHeap::entry_evac() {
2322 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
2323 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2324
2325 static const char *msg = "Concurrent evacuation";
2326 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2327 EventMark em("%s", msg);
2328
2329 ShenandoahWorkerScope scope(workers(),
2330 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2331 "concurrent evacuation");
2332
2333 try_inject_alloc_failure();
2334 op_conc_evac();
2335 }
2336
2337 void ShenandoahHeap::entry_updaterefs() {
2338 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
2339
2340 static const char* msg = "Concurrent update references";
2341 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2342 EventMark em("%s", msg);
2343
2344 ShenandoahWorkerScope scope(workers(),
2345 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2346 "concurrent reference update");
2347
2348 try_inject_alloc_failure();
2349 op_updaterefs();
2350 }
2351
2352 void ShenandoahHeap::entry_cleanup() {
2353 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup);
2354
2355 static const char* msg = "Concurrent cleanup";
2356 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2357 EventMark em("%s", msg);
2358
2359 // This phase does not use workers, no need for setup
2360
2361 try_inject_alloc_failure();
2362 op_cleanup();
2363 }
2364
2365 void ShenandoahHeap::entry_reset() {
2366 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset);
2367
2368 static const char* msg = "Concurrent reset";
2369 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2370 EventMark em("%s", msg);
2371
2372 ShenandoahWorkerScope scope(workers(),
2373 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2374 "concurrent reset");
2375
2376 try_inject_alloc_failure();
2377 op_reset();
2378 }
2379
2380 void ShenandoahHeap::entry_preclean() {
2381 if (ShenandoahPreclean && process_references()) {
2382 ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
2383
2384 static const char* msg = "Concurrent precleaning";
2385 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2386 EventMark em("%s", msg);
2387
2388 ShenandoahWorkerScope scope(workers(),
2389 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2390 "concurrent preclean",
2391 /* check_workers = */ false);
2392
2393 try_inject_alloc_failure();
2394 op_preclean();
2395 }
2396 }
2397
2398 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2399 static const char *msg = "Concurrent uncommit";
2400 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2401 EventMark em("%s", msg);
2402
2403 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit);
2404
2405 op_uncommit(shrink_before);
2406 }
2407
2408 void ShenandoahHeap::try_inject_alloc_failure() {
2409 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2410 _inject_alloc_failure.set();
2411 os::naked_short_sleep(1);
2412 if (cancelled_gc()) {
2413 log_info(gc)("Allocation failure was successfully injected");
2414 }
2415 }
2416 }
2417
2418 bool ShenandoahHeap::should_inject_alloc_failure() {
2419 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2420 }
2421
2422 void ShenandoahHeap::enter_evacuation() {
2423 _oom_evac_handler.enter_evacuation();
2424 }
2425
2426 void ShenandoahHeap::leave_evacuation() {
2427 _oom_evac_handler.leave_evacuation();
2428 }
2429
2430 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2431 _heap(ShenandoahHeap::heap()),
2432 _index(0) {}
2433
2434 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2435 _heap(heap),
2436 _index(0) {}
2437
2438 void ShenandoahRegionIterator::reset() {
2439 _index = 0;
2440 }
2441
2442 bool ShenandoahRegionIterator::has_next() const {
2443 return _index < (jint)_heap->num_regions();
2444 }
2445
2446 char ShenandoahHeap::gc_state() {
2447 return _gc_state.raw_value();
2448 }
2449
2450 const char* ShenandoahHeap::init_mark_event_message() const {
2451 bool update_refs = has_forwarded_objects();
2452 bool proc_refs = process_references();
2453 bool unload_cls = unload_classes();
2454
2455 if (update_refs && proc_refs && unload_cls) {
2456 return "Pause Init Mark (update refs) (process weakrefs) (unload classes)";
2457 } else if (update_refs && proc_refs) {
2458 return "Pause Init Mark (update refs) (process weakrefs)";
2459 } else if (update_refs && unload_cls) {
2460 return "Pause Init Mark (update refs) (unload classes)";
2461 } else if (proc_refs && unload_cls) {
2462 return "Pause Init Mark (process weakrefs) (unload classes)";
2463 } else if (update_refs) {
2464 return "Pause Init Mark (update refs)";
2465 } else if (proc_refs) {
2466 return "Pause Init Mark (process weakrefs)";
2467 } else if (unload_cls) {
2468 return "Pause Init Mark (unload classes)";
2469 } else {
2470 return "Pause Init Mark";
2471 }
2472 }
2473
2474 const char* ShenandoahHeap::final_mark_event_message() const {
2475 bool update_refs = has_forwarded_objects();
2476 bool proc_refs = process_references();
2477 bool unload_cls = unload_classes();
2478
2479 if (update_refs && proc_refs && unload_cls) {
2480 return "Pause Final Mark (update refs) (process weakrefs) (unload classes)";
2481 } else if (update_refs && proc_refs) {
2482 return "Pause Final Mark (update refs) (process weakrefs)";
2483 } else if (update_refs && unload_cls) {
2484 return "Pause Final Mark (update refs) (unload classes)";
2485 } else if (proc_refs && unload_cls) {
2486 return "Pause Final Mark (process weakrefs) (unload classes)";
2487 } else if (update_refs) {
2488 return "Pause Final Mark (update refs)";
2489 } else if (proc_refs) {
2490 return "Pause Final Mark (process weakrefs)";
2491 } else if (unload_cls) {
2492 return "Pause Final Mark (unload classes)";
2493 } else {
2494 return "Pause Final Mark";
2495 }
2496 }
2497
2498 const char* ShenandoahHeap::conc_mark_event_message() const {
2499 bool update_refs = has_forwarded_objects();
2500 bool proc_refs = process_references();
2501 bool unload_cls = unload_classes();
2502
2503 if (update_refs && proc_refs && unload_cls) {
2504 return "Concurrent marking (update refs) (process weakrefs) (unload classes)";
2505 } else if (update_refs && proc_refs) {
2506 return "Concurrent marking (update refs) (process weakrefs)";
2507 } else if (update_refs && unload_cls) {
2508 return "Concurrent marking (update refs) (unload classes)";
2509 } else if (proc_refs && unload_cls) {
2510 return "Concurrent marking (process weakrefs) (unload classes)";
2511 } else if (update_refs) {
2512 return "Concurrent marking (update refs)";
2513 } else if (proc_refs) {
2514 return "Concurrent marking (process weakrefs)";
2515 } else if (unload_cls) {
2516 return "Concurrent marking (unload classes)";
2517 } else {
2518 return "Concurrent marking";
2519 }
2520 }
2521
2522 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
2523 switch (point) {
2524 case _degenerated_unset:
2525 return "Pause Degenerated GC (<UNSET>)";
2526 case _degenerated_outside_cycle:
2527 return "Pause Degenerated GC (Outside of Cycle)";
2528 case _degenerated_mark:
2529 return "Pause Degenerated GC (Mark)";
2530 case _degenerated_evac:
2531 return "Pause Degenerated GC (Evacuation)";
2532 case _degenerated_updaterefs:
2533 return "Pause Degenerated GC (Update Refs)";
2534 default:
2535 ShouldNotReachHere();
2536 return "ERROR";
2537 }
2538 }
2539
2540 jushort* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2541 #ifdef ASSERT
2542 assert(worker_id < _max_workers, "sanity");
2543 for (uint i = 0; i < num_regions(); i++) {
2544 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2545 }
2546 #endif
2547 return _liveness_cache[worker_id];
2548 }
2549
2550 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2551 assert(worker_id < _max_workers, "sanity");
2552 jushort* ld = _liveness_cache[worker_id];
2553 for (uint i = 0; i < num_regions(); i++) {
2554 ShenandoahHeapRegion* r = get_region(i);
2555 jushort live = ld[i];
2556 if (live > 0) {
2557 r->increase_live_data_gc_words(live);
2558 ld[i] = 0;
2559 }
2560 }
2561 }
2562
2563 BoolObjectClosure* ShenandoahIsAliveSelector::is_alive_closure() {
2564 return ShenandoahHeap::heap()->has_forwarded_objects() ? reinterpret_cast<BoolObjectClosure*>(&_fwd_alive_cl)
2565 : reinterpret_cast<BoolObjectClosure*>(&_alive_cl);
2566 }