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