1 /*
2 * Copyright (c) 2013, 2019, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #include "precompiled.hpp"
25 #include "memory/allocation.hpp"
26 #include "memory/universe.hpp"
27
28 #include "gc/shared/gcArguments.hpp"
29 #include "gc/shared/gcTimer.hpp"
30 #include "gc/shared/gcTraceTime.inline.hpp"
31 #include "gc/shared/locationPrinter.inline.hpp"
32 #include "gc/shared/memAllocator.hpp"
33 #include "gc/shared/plab.hpp"
34
35 #include "gc/shenandoah/shenandoahAllocTracker.hpp"
36 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
37 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
38 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
39 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
40 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
41 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
42 #include "gc/shenandoah/shenandoahControlThread.hpp"
43 #include "gc/shenandoah/shenandoahFreeSet.hpp"
44 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
45 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
46 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
47 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
48 #include "gc/shenandoah/shenandoahMarkCompact.hpp"
49 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
50 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
51 #include "gc/shenandoah/shenandoahMetrics.hpp"
52 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
53 #include "gc/shenandoah/shenandoahNormalMode.hpp"
54 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
55 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
56 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
57 #include "gc/shenandoah/shenandoahPassiveMode.hpp"
58 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
59 #include "gc/shenandoah/shenandoahStringDedup.hpp"
60 #include "gc/shenandoah/shenandoahTaskqueue.hpp"
61 #include "gc/shenandoah/shenandoahTraversalMode.hpp"
62 #include "gc/shenandoah/shenandoahUtils.hpp"
63 #include "gc/shenandoah/shenandoahVerifier.hpp"
64 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
65 #include "gc/shenandoah/shenandoahVMOperations.hpp"
66 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
67 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
68 #if INCLUDE_JFR
69 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
70 #endif
71
72 #include "memory/metaspace.hpp"
73 #include "oops/compressedOops.inline.hpp"
74 #include "runtime/atomic.hpp"
75 #include "runtime/globals.hpp"
76 #include "runtime/interfaceSupport.inline.hpp"
77 #include "runtime/orderAccess.hpp"
78 #include "runtime/safepointMechanism.hpp"
79 #include "runtime/vmThread.hpp"
80 #include "services/mallocTracker.hpp"
81
82 #ifdef ASSERT
83 template <class T>
84 void ShenandoahAssertToSpaceClosure::do_oop_work(T* p) {
85 T o = RawAccess<>::oop_load(p);
86 if (! CompressedOops::is_null(o)) {
87 oop obj = CompressedOops::decode_not_null(o);
88 shenandoah_assert_not_forwarded(p, obj);
89 }
90 }
91
92 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_work(p); }
93 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_work(p); }
94 #endif
95
96 class ShenandoahPretouchHeapTask : public AbstractGangTask {
97 private:
98 ShenandoahRegionIterator _regions;
99 const size_t _page_size;
100 public:
101 ShenandoahPretouchHeapTask(size_t page_size) :
102 AbstractGangTask("Shenandoah Pretouch Heap"),
103 _page_size(page_size) {}
104
105 virtual void work(uint worker_id) {
106 ShenandoahHeapRegion* r = _regions.next();
107 while (r != NULL) {
108 os::pretouch_memory(r->bottom(), r->end(), _page_size);
109 r = _regions.next();
110 }
111 }
112 };
113
114 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
115 private:
116 ShenandoahRegionIterator _regions;
117 char* _bitmap_base;
118 const size_t _bitmap_size;
119 const size_t _page_size;
120 public:
121 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
122 AbstractGangTask("Shenandoah Pretouch Bitmap"),
123 _bitmap_base(bitmap_base),
124 _bitmap_size(bitmap_size),
125 _page_size(page_size) {}
126
127 virtual void work(uint worker_id) {
128 ShenandoahHeapRegion* r = _regions.next();
129 while (r != NULL) {
130 size_t start = r->region_number() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
131 size_t end = (r->region_number() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
132 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
133
134 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
135
136 r = _regions.next();
137 }
138 }
139 };
140
141 jint ShenandoahHeap::initialize() {
142 initialize_heuristics();
143
144 //
145 // Figure out heap sizing
146 //
147
148 size_t init_byte_size = InitialHeapSize;
149 size_t min_byte_size = MinHeapSize;
150 size_t max_byte_size = MaxHeapSize;
151 size_t heap_alignment = HeapAlignment;
152
153 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
154
155 if (ShenandoahAlwaysPreTouch) {
156 // Enabled pre-touch means the entire heap is committed right away.
157 init_byte_size = max_byte_size;
158 }
159
160 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
161 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
162
163 _num_regions = ShenandoahHeapRegion::region_count();
164
165 size_t num_committed_regions = init_byte_size / reg_size_bytes;
166 num_committed_regions = MIN2(num_committed_regions, _num_regions);
167 assert(num_committed_regions <= _num_regions, "sanity");
168 _initial_size = num_committed_regions * reg_size_bytes;
169
170 size_t num_min_regions = min_byte_size / reg_size_bytes;
171 num_min_regions = MIN2(num_min_regions, _num_regions);
172 assert(num_min_regions <= _num_regions, "sanity");
173 _minimum_size = num_min_regions * reg_size_bytes;
174
175 _committed = _initial_size;
176
177 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
178 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
179
180 //
181 // Reserve and commit memory for heap
182 //
183
184 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
185 initialize_reserved_region(heap_rs);
186 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
187 _heap_region_special = heap_rs.special();
188
189 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
190 "Misaligned heap: " PTR_FORMAT, p2i(base()));
191
192 #if SHENANDOAH_OPTIMIZED_OBJTASK
193 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
194 // Fail if we ever attempt to address more than we can.
195 if ((uintptr_t)heap_rs.end() >= ObjArrayChunkedTask::max_addressable()) {
196 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
197 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
198 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
199 p2i(heap_rs.base()), p2i(heap_rs.end()), ObjArrayChunkedTask::max_addressable());
200 vm_exit_during_initialization("Fatal Error", buf);
201 }
202 #endif
203
204 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
205 if (!_heap_region_special) {
206 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
207 "Cannot commit heap memory");
208 }
209
210 //
211 // Reserve and commit memory for bitmap(s)
212 //
213
214 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
215 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
216
217 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
218
219 guarantee(bitmap_bytes_per_region != 0,
220 "Bitmap bytes per region should not be zero");
221 guarantee(is_power_of_2(bitmap_bytes_per_region),
222 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
223
224 if (bitmap_page_size > bitmap_bytes_per_region) {
225 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
226 _bitmap_bytes_per_slice = bitmap_page_size;
227 } else {
228 _bitmap_regions_per_slice = 1;
229 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
230 }
231
232 guarantee(_bitmap_regions_per_slice >= 1,
233 "Should have at least one region per slice: " SIZE_FORMAT,
234 _bitmap_regions_per_slice);
235
236 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
237 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
238 _bitmap_bytes_per_slice, bitmap_page_size);
239
240 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
241 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
242 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
243 _bitmap_region_special = bitmap.special();
244
245 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
246 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
247 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
248 if (!_bitmap_region_special) {
249 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
250 "Cannot commit bitmap memory");
251 }
252
253 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
254
255 if (ShenandoahVerify) {
256 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
257 if (!verify_bitmap.special()) {
258 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
259 "Cannot commit verification bitmap memory");
260 }
261 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
262 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
263 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
264 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
265 }
266
267 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
268 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
269 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
270 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
271 _aux_bitmap_region_special = aux_bitmap.special();
272 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
273
274 //
275 // Create regions and region sets
276 //
277
278 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
279 _free_set = new ShenandoahFreeSet(this, _num_regions);
280 _collection_set = new ShenandoahCollectionSet(this, sh_rs.base(), sh_rs.size());
281
282 {
283 ShenandoahHeapLocker locker(lock());
284
285 size_t size_words = ShenandoahHeapRegion::region_size_words();
286
287 for (size_t i = 0; i < _num_regions; i++) {
288 HeapWord* start = (HeapWord*)sh_rs.base() + size_words * i;
289 bool is_committed = i < num_committed_regions;
290 ShenandoahHeapRegion* r = new ShenandoahHeapRegion(this, start, size_words, i, is_committed);
291
292 _marking_context->initialize_top_at_mark_start(r);
293 _regions[i] = r;
294 assert(!collection_set()->is_in(i), "New region should not be in collection set");
295 }
296
297 // Initialize to complete
298 _marking_context->mark_complete();
299
300 _free_set->rebuild();
301 }
302
303 if (ShenandoahAlwaysPreTouch) {
304 assert(!AlwaysPreTouch, "Should have been overridden");
305
306 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
307 // before initialize() below zeroes it with initializing thread. For any given region,
308 // we touch the region and the corresponding bitmaps from the same thread.
309 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
310
311 size_t pretouch_heap_page_size = heap_page_size;
312 size_t pretouch_bitmap_page_size = bitmap_page_size;
313
314 #ifdef LINUX
315 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
316 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
317 // them into huge one. Therefore, we need to pretouch with smaller pages.
318 if (UseTransparentHugePages) {
319 pretouch_heap_page_size = (size_t)os::vm_page_size();
320 pretouch_bitmap_page_size = (size_t)os::vm_page_size();
321 }
322 #endif
323
324 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
325 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
326
327 log_info(gc, init)("Pretouch bitmap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
328 _num_regions, pretouch_bitmap_page_size);
329 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, pretouch_bitmap_page_size);
330 _workers->run_task(&bcl);
331
332 log_info(gc, init)("Pretouch heap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
333 _num_regions, pretouch_heap_page_size);
334 ShenandoahPretouchHeapTask hcl(pretouch_heap_page_size);
335 _workers->run_task(&hcl);
336 }
337
338 //
339 // Initialize the rest of GC subsystems
340 //
341
342 _liveness_cache = NEW_C_HEAP_ARRAY(jushort*, _max_workers, mtGC);
343 for (uint worker = 0; worker < _max_workers; worker++) {
344 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(jushort, _num_regions, mtGC);
345 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(jushort));
346 }
347
348 // There should probably be Shenandoah-specific options for these,
349 // just as there are G1-specific options.
350 {
351 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
352 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
353 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
354 }
355
356 _monitoring_support = new ShenandoahMonitoringSupport(this);
357 _phase_timings = new ShenandoahPhaseTimings();
358 ShenandoahStringDedup::initialize();
359 ShenandoahCodeRoots::initialize();
360
361 if (ShenandoahAllocationTrace) {
362 _alloc_tracker = new ShenandoahAllocTracker();
363 }
364
365 if (ShenandoahPacing) {
366 _pacer = new ShenandoahPacer(this);
367 _pacer->setup_for_idle();
368 } else {
369 _pacer = NULL;
370 }
371
372 _traversal_gc = strcmp(ShenandoahGCMode, "traversal") == 0 ?
373 new ShenandoahTraversalGC(this, _num_regions) :
374 NULL;
375
376 _control_thread = new ShenandoahControlThread();
377
378 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max",
379 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size),
380 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size),
381 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity())
382 );
383
384 log_info(gc, init)("Safepointing mechanism: %s",
385 SafepointMechanism::uses_thread_local_poll() ? "thread-local poll" :
386 (SafepointMechanism::uses_global_page_poll() ? "global-page poll" : "unknown"));
387
388 return JNI_OK;
389 }
390
391 void ShenandoahHeap::initialize_heuristics() {
392 if (ShenandoahGCMode != NULL) {
393 if (strcmp(ShenandoahGCMode, "traversal") == 0) {
394 _gc_mode = new ShenandoahTraversalMode();
395 } else if (strcmp(ShenandoahGCMode, "normal") == 0) {
396 _gc_mode = new ShenandoahNormalMode();
397 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
398 _gc_mode = new ShenandoahPassiveMode();
399 } else {
400 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
401 }
402 } else {
403 ShouldNotReachHere();
404 }
405 _gc_mode->initialize_flags();
406 _heuristics = _gc_mode->initialize_heuristics();
407
408 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
409 vm_exit_during_initialization(
410 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
411 _heuristics->name()));
412 }
413 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
414 vm_exit_during_initialization(
415 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
416 _heuristics->name()));
417 }
418 log_info(gc, init)("Shenandoah heuristics: %s",
419 _heuristics->name());
420 }
421
422 #ifdef _MSC_VER
423 #pragma warning( push )
424 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
425 #endif
426
427 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
428 CollectedHeap(),
429 _initial_size(0),
430 _used(0),
431 _committed(0),
432 _bytes_allocated_since_gc_start(0),
433 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
434 _workers(NULL),
435 _safepoint_workers(NULL),
436 _heap_region_special(false),
437 _num_regions(0),
438 _regions(NULL),
439 _update_refs_iterator(this),
440 _control_thread(NULL),
441 _shenandoah_policy(policy),
442 _heuristics(NULL),
443 _free_set(NULL),
444 _scm(new ShenandoahConcurrentMark()),
445 _traversal_gc(NULL),
446 _full_gc(new ShenandoahMarkCompact()),
447 _pacer(NULL),
448 _verifier(NULL),
449 _alloc_tracker(NULL),
450 _phase_timings(NULL),
451 _monitoring_support(NULL),
452 _memory_pool(NULL),
453 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
454 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
455 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
456 _soft_ref_policy(),
457 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
458 _ref_processor(NULL),
459 _marking_context(NULL),
460 _bitmap_size(0),
461 _bitmap_regions_per_slice(0),
462 _bitmap_bytes_per_slice(0),
463 _bitmap_region_special(false),
464 _aux_bitmap_region_special(false),
465 _liveness_cache(NULL),
466 _collection_set(NULL)
467 {
468 log_info(gc, init)("GC threads: " UINT32_FORMAT " parallel, " UINT32_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
469 log_info(gc, init)("Reference processing: %s", ParallelRefProcEnabled ? "parallel" : "serial");
470
471 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
472
473 _max_workers = MAX2(_max_workers, 1U);
474 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
475 /* are_GC_task_threads */ true,
476 /* are_ConcurrentGC_threads */ true);
477 if (_workers == NULL) {
478 vm_exit_during_initialization("Failed necessary allocation.");
479 } else {
480 _workers->initialize_workers();
481 }
482
483 if (ShenandoahParallelSafepointThreads > 1) {
484 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
485 ShenandoahParallelSafepointThreads,
486 /* are_GC_task_threads */ false,
487 /* are_ConcurrentGC_threads */ false);
488 _safepoint_workers->initialize_workers();
489 }
490 }
491
492 #ifdef _MSC_VER
493 #pragma warning( pop )
494 #endif
495
496 class ShenandoahResetBitmapTask : public AbstractGangTask {
497 private:
498 ShenandoahRegionIterator _regions;
499
500 public:
501 ShenandoahResetBitmapTask() :
502 AbstractGangTask("Parallel Reset Bitmap Task") {}
503
504 void work(uint worker_id) {
505 ShenandoahHeapRegion* region = _regions.next();
506 ShenandoahHeap* heap = ShenandoahHeap::heap();
507 ShenandoahMarkingContext* const ctx = heap->marking_context();
508 while (region != NULL) {
509 if (heap->is_bitmap_slice_committed(region)) {
510 ctx->clear_bitmap(region);
511 }
512 region = _regions.next();
513 }
514 }
515 };
516
517 void ShenandoahHeap::reset_mark_bitmap() {
518 assert_gc_workers(_workers->active_workers());
519 mark_incomplete_marking_context();
520
521 ShenandoahResetBitmapTask task;
522 _workers->run_task(&task);
523 }
524
525 void ShenandoahHeap::print_on(outputStream* st) const {
526 st->print_cr("Shenandoah Heap");
527 st->print_cr(" " SIZE_FORMAT "%s total, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
528 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
529 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
530 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
531 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
532 num_regions(),
533 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
534 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
535
536 st->print("Status: ");
537 if (has_forwarded_objects()) st->print("has forwarded objects, ");
538 if (is_concurrent_mark_in_progress()) st->print("marking, ");
539 if (is_evacuation_in_progress()) st->print("evacuating, ");
540 if (is_update_refs_in_progress()) st->print("updating refs, ");
541 if (is_concurrent_traversal_in_progress()) st->print("traversal, ");
542 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
543 if (is_full_gc_in_progress()) st->print("full gc, ");
544 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
545
546 if (cancelled_gc()) {
547 st->print("cancelled");
548 } else {
549 st->print("not cancelled");
550 }
551 st->cr();
552
553 st->print_cr("Reserved region:");
554 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
555 p2i(reserved_region().start()),
556 p2i(reserved_region().end()));
557
558 ShenandoahCollectionSet* cset = collection_set();
559 st->print_cr("Collection set:");
560 if (cset != NULL) {
561 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
562 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
563 } else {
564 st->print_cr(" (NULL)");
565 }
566
567 st->cr();
568 MetaspaceUtils::print_on(st);
569
570 if (Verbose) {
571 print_heap_regions_on(st);
572 }
573 }
574
575 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
576 public:
577 void do_thread(Thread* thread) {
578 assert(thread != NULL, "Sanity");
579 assert(thread->is_Worker_thread(), "Only worker thread expected");
580 ShenandoahThreadLocalData::initialize_gclab(thread);
581 }
582 };
583
584 void ShenandoahHeap::post_initialize() {
585 CollectedHeap::post_initialize();
586 MutexLocker ml(Threads_lock);
587
588 ShenandoahInitWorkerGCLABClosure init_gclabs;
589 _workers->threads_do(&init_gclabs);
590
591 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
592 // Now, we will let WorkGang to initialize gclab when new worker is created.
593 _workers->set_initialize_gclab();
594
595 _scm->initialize(_max_workers);
596 _full_gc->initialize(_gc_timer);
597
598 ref_processing_init();
599
600 _heuristics->initialize();
601
602 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
603 }
604
605 size_t ShenandoahHeap::used() const {
606 return Atomic::load_acquire(&_used);
607 }
608
609 size_t ShenandoahHeap::committed() const {
610 OrderAccess::acquire();
611 return _committed;
612 }
613
614 void ShenandoahHeap::increase_committed(size_t bytes) {
615 assert_heaplock_or_safepoint();
616 _committed += bytes;
617 }
618
619 void ShenandoahHeap::decrease_committed(size_t bytes) {
620 assert_heaplock_or_safepoint();
621 _committed -= bytes;
622 }
623
624 void ShenandoahHeap::increase_used(size_t bytes) {
625 Atomic::add(&_used, bytes);
626 }
627
628 void ShenandoahHeap::set_used(size_t bytes) {
629 Atomic::release_store_fence(&_used, bytes);
630 }
631
632 void ShenandoahHeap::decrease_used(size_t bytes) {
633 assert(used() >= bytes, "never decrease heap size by more than we've left");
634 Atomic::sub(&_used, bytes);
635 }
636
637 void ShenandoahHeap::increase_allocated(size_t bytes) {
638 Atomic::add(&_bytes_allocated_since_gc_start, bytes);
639 }
640
641 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
642 size_t bytes = words * HeapWordSize;
643 if (!waste) {
644 increase_used(bytes);
645 }
646 increase_allocated(bytes);
647 if (ShenandoahPacing) {
648 control_thread()->pacing_notify_alloc(words);
649 if (waste) {
650 pacer()->claim_for_alloc(words, true);
651 }
652 }
653 }
654
655 size_t ShenandoahHeap::capacity() const {
656 return committed();
657 }
658
659 size_t ShenandoahHeap::max_capacity() const {
660 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
661 }
662
663 size_t ShenandoahHeap::min_capacity() const {
664 return _minimum_size;
665 }
666
667 size_t ShenandoahHeap::initial_capacity() const {
668 return _initial_size;
669 }
670
671 bool ShenandoahHeap::is_in(const void* p) const {
672 HeapWord* heap_base = (HeapWord*) base();
673 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
674 return p >= heap_base && p < last_region_end;
675 }
676
677 void ShenandoahHeap::op_uncommit(double shrink_before) {
678 assert (ShenandoahUncommit, "should be enabled");
679
680 // Application allocates from the beginning of the heap, and GC allocates at
681 // the end of it. It is more efficient to uncommit from the end, so that applications
682 // could enjoy the near committed regions. GC allocations are much less frequent,
683 // and therefore can accept the committing costs.
684
685 size_t count = 0;
686 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
687 ShenandoahHeapRegion* r = get_region(i - 1);
688 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
689 ShenandoahHeapLocker locker(lock());
690 if (r->is_empty_committed()) {
691 // Do not uncommit below minimal capacity
692 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
693 break;
694 }
695
696 r->make_uncommitted();
697 count++;
698 }
699 }
700 SpinPause(); // allow allocators to take the lock
701 }
702
703 if (count > 0) {
704 control_thread()->notify_heap_changed();
705 }
706 }
707
708 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
709 // New object should fit the GCLAB size
710 size_t min_size = MAX2(size, PLAB::min_size());
711
712 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
713 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
714 new_size = MIN2(new_size, PLAB::max_size());
715 new_size = MAX2(new_size, PLAB::min_size());
716
717 // Record new heuristic value even if we take any shortcut. This captures
718 // the case when moderately-sized objects always take a shortcut. At some point,
719 // heuristics should catch up with them.
720 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
721
722 if (new_size < size) {
723 // New size still does not fit the object. Fall back to shared allocation.
724 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
725 return NULL;
726 }
727
728 // Retire current GCLAB, and allocate a new one.
729 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
730 gclab->retire();
731
732 size_t actual_size = 0;
733 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
734 if (gclab_buf == NULL) {
735 return NULL;
736 }
737
738 assert (size <= actual_size, "allocation should fit");
739
740 if (ZeroTLAB) {
741 // ..and clear it.
742 Copy::zero_to_words(gclab_buf, actual_size);
743 } else {
744 // ...and zap just allocated object.
745 #ifdef ASSERT
746 // Skip mangling the space corresponding to the object header to
747 // ensure that the returned space is not considered parsable by
748 // any concurrent GC thread.
749 size_t hdr_size = oopDesc::header_size();
750 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
751 #endif // ASSERT
752 }
753 gclab->set_buf(gclab_buf, actual_size);
754 return gclab->allocate(size);
755 }
756
757 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
758 size_t requested_size,
759 size_t* actual_size) {
760 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
761 HeapWord* res = allocate_memory(req);
762 if (res != NULL) {
763 *actual_size = req.actual_size();
764 } else {
765 *actual_size = 0;
766 }
767 return res;
768 }
769
770 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
771 size_t word_size,
772 size_t* actual_size) {
773 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
774 HeapWord* res = allocate_memory(req);
775 if (res != NULL) {
776 *actual_size = req.actual_size();
777 } else {
778 *actual_size = 0;
779 }
780 return res;
781 }
782
783 ShenandoahHeap* ShenandoahHeap::heap() {
784 CollectedHeap* heap = Universe::heap();
785 assert(heap != NULL, "Unitialized access to ShenandoahHeap::heap()");
786 assert(heap->kind() == CollectedHeap::Shenandoah, "not a shenandoah heap");
787 return (ShenandoahHeap*) heap;
788 }
789
790 ShenandoahHeap* ShenandoahHeap::heap_no_check() {
791 CollectedHeap* heap = Universe::heap();
792 return (ShenandoahHeap*) heap;
793 }
794
795 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
796 ShenandoahAllocTrace trace_alloc(req.size(), req.type());
797
798 intptr_t pacer_epoch = 0;
799 bool in_new_region = false;
800 HeapWord* result = NULL;
801
802 if (req.is_mutator_alloc()) {
803 if (ShenandoahPacing) {
804 pacer()->pace_for_alloc(req.size());
805 pacer_epoch = pacer()->epoch();
806 }
807
808 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
809 result = allocate_memory_under_lock(req, in_new_region);
810 }
811
812 // Allocation failed, block until control thread reacted, then retry allocation.
813 //
814 // It might happen that one of the threads requesting allocation would unblock
815 // way later after GC happened, only to fail the second allocation, because
816 // other threads have already depleted the free storage. In this case, a better
817 // strategy is to try again, as long as GC makes progress.
818 //
819 // Then, we need to make sure the allocation was retried after at least one
820 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
821
822 size_t tries = 0;
823
824 while (result == NULL && _progress_last_gc.is_set()) {
825 tries++;
826 control_thread()->handle_alloc_failure(req.size());
827 result = allocate_memory_under_lock(req, in_new_region);
828 }
829
830 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
831 tries++;
832 control_thread()->handle_alloc_failure(req.size());
833 result = allocate_memory_under_lock(req, in_new_region);
834 }
835
836 } else {
837 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
838 result = allocate_memory_under_lock(req, in_new_region);
839 // Do not call handle_alloc_failure() here, because we cannot block.
840 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
841 }
842
843 if (in_new_region) {
844 control_thread()->notify_heap_changed();
845 }
846
847 if (result != NULL) {
848 size_t requested = req.size();
849 size_t actual = req.actual_size();
850
851 assert (req.is_lab_alloc() || (requested == actual),
852 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
853 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
854
855 if (req.is_mutator_alloc()) {
856 notify_mutator_alloc_words(actual, false);
857
858 // If we requested more than we were granted, give the rest back to pacer.
859 // This only matters if we are in the same pacing epoch: do not try to unpace
860 // over the budget for the other phase.
861 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
862 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
863 }
864 } else {
865 increase_used(actual*HeapWordSize);
866 }
867 }
868
869 return result;
870 }
871
872 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
873 ShenandoahHeapLocker locker(lock());
874 return _free_set->allocate(req, in_new_region);
875 }
876
877 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
878 bool* gc_overhead_limit_was_exceeded) {
879 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
880 return allocate_memory(req);
881 }
882
883 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
884 size_t size,
885 Metaspace::MetadataType mdtype) {
886 MetaWord* result;
887
888 // Inform metaspace OOM to GC heuristics if class unloading is possible.
889 if (heuristics()->can_unload_classes()) {
890 ShenandoahHeuristics* h = heuristics();
891 h->record_metaspace_oom();
892 }
893
894 // Expand and retry allocation
895 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
896 if (result != NULL) {
897 return result;
898 }
899
900 // Start full GC
901 collect(GCCause::_metadata_GC_clear_soft_refs);
902
903 // Retry allocation
904 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
905 if (result != NULL) {
906 return result;
907 }
908
909 // Expand and retry allocation
910 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
911 if (result != NULL) {
912 return result;
913 }
914
915 // Out of memory
916 return NULL;
917 }
918
919 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
920 private:
921 ShenandoahHeap* const _heap;
922 Thread* const _thread;
923 public:
924 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
925 _heap(heap), _thread(Thread::current()) {}
926
927 void do_object(oop p) {
928 shenandoah_assert_marked(NULL, p);
929 if (!p->is_forwarded()) {
930 _heap->evacuate_object(p, _thread);
931 }
932 }
933 };
934
935 class ShenandoahEvacuationTask : public AbstractGangTask {
936 private:
937 ShenandoahHeap* const _sh;
938 ShenandoahCollectionSet* const _cs;
939 bool _concurrent;
940 public:
941 ShenandoahEvacuationTask(ShenandoahHeap* sh,
942 ShenandoahCollectionSet* cs,
943 bool concurrent) :
944 AbstractGangTask("Parallel Evacuation Task"),
945 _sh(sh),
946 _cs(cs),
947 _concurrent(concurrent)
948 {}
949
950 void work(uint worker_id) {
951 if (_concurrent) {
952 ShenandoahConcurrentWorkerSession worker_session(worker_id);
953 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
954 ShenandoahEvacOOMScope oom_evac_scope;
955 do_work();
956 } else {
957 ShenandoahParallelWorkerSession worker_session(worker_id);
958 ShenandoahEvacOOMScope oom_evac_scope;
959 do_work();
960 }
961 }
962
963 private:
964 void do_work() {
965 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
966 ShenandoahHeapRegion* r;
967 while ((r =_cs->claim_next()) != NULL) {
968 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->region_number());
969 _sh->marked_object_iterate(r, &cl);
970
971 if (ShenandoahPacing) {
972 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
973 }
974
975 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
976 break;
977 }
978 }
979 }
980 };
981
982 void ShenandoahHeap::trash_cset_regions() {
983 ShenandoahHeapLocker locker(lock());
984
985 ShenandoahCollectionSet* set = collection_set();
986 ShenandoahHeapRegion* r;
987 set->clear_current_index();
988 while ((r = set->next()) != NULL) {
989 r->make_trash();
990 }
991 collection_set()->clear();
992 }
993
994 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
995 st->print_cr("Heap Regions:");
996 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
997 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
998 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start (previous, next)");
999 st->print_cr("SN=alloc sequence numbers (first mutator, last mutator, first gc, last gc)");
1000
1001 for (size_t i = 0; i < num_regions(); i++) {
1002 get_region(i)->print_on(st);
1003 }
1004 }
1005
1006 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1007 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1008
1009 oop humongous_obj = oop(start->bottom());
1010 size_t size = humongous_obj->size();
1011 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1012 size_t index = start->region_number() + required_regions - 1;
1013
1014 assert(!start->has_live(), "liveness must be zero");
1015
1016 for(size_t i = 0; i < required_regions; i++) {
1017 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1018 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1019 ShenandoahHeapRegion* region = get_region(index --);
1020
1021 assert(region->is_humongous(), "expect correct humongous start or continuation");
1022 assert(!region->is_cset(), "Humongous region should not be in collection set");
1023
1024 region->make_trash_immediate();
1025 }
1026 }
1027
1028 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1029 public:
1030 void do_thread(Thread* thread) {
1031 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1032 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1033 gclab->retire();
1034 }
1035 };
1036
1037 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
1038 if (UseTLAB) {
1039 CollectedHeap::ensure_parsability(retire_tlabs);
1040 }
1041 ShenandoahRetireGCLABClosure cl;
1042 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1043 cl.do_thread(t);
1044 }
1045 workers()->threads_do(&cl);
1046 }
1047
1048 void ShenandoahHeap::resize_tlabs() {
1049 CollectedHeap::resize_all_tlabs();
1050 }
1051
1052 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1053 private:
1054 ShenandoahRootEvacuator* _rp;
1055
1056 public:
1057 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1058 AbstractGangTask("Shenandoah evacuate and update roots"),
1059 _rp(rp) {}
1060
1061 void work(uint worker_id) {
1062 ShenandoahParallelWorkerSession worker_session(worker_id);
1063 ShenandoahEvacOOMScope oom_evac_scope;
1064 ShenandoahEvacuateUpdateRootsClosure cl;
1065 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1066 _rp->roots_do(worker_id, &cl);
1067 }
1068 };
1069
1070 void ShenandoahHeap::evacuate_and_update_roots() {
1071 #if COMPILER2_OR_JVMCI
1072 DerivedPointerTable::clear();
1073 #endif
1074 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1075 {
1076 // Include concurrent roots if current cycle can not process those roots concurrently
1077 ShenandoahRootEvacuator rp(workers()->active_workers(),
1078 ShenandoahPhaseTimings::init_evac,
1079 !ShenandoahConcurrentRoots::should_do_concurrent_roots());
1080 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1081 workers()->run_task(&roots_task);
1082 }
1083
1084 #if COMPILER2_OR_JVMCI
1085 DerivedPointerTable::update_pointers();
1086 #endif
1087 }
1088
1089 // Returns size in bytes
1090 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1091 if (ShenandoahElasticTLAB) {
1092 // With Elastic TLABs, return the max allowed size, and let the allocation path
1093 // figure out the safe size for current allocation.
1094 return ShenandoahHeapRegion::max_tlab_size_bytes();
1095 } else {
1096 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1097 }
1098 }
1099
1100 size_t ShenandoahHeap::max_tlab_size() const {
1101 // Returns size in words
1102 return ShenandoahHeapRegion::max_tlab_size_words();
1103 }
1104
1105 class ShenandoahRetireAndResetGCLABClosure : public ThreadClosure {
1106 public:
1107 void do_thread(Thread* thread) {
1108 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1109 gclab->retire();
1110 if (ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1111 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1112 }
1113 }
1114 };
1115
1116 void ShenandoahHeap::retire_and_reset_gclabs() {
1117 ShenandoahRetireAndResetGCLABClosure cl;
1118 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1119 cl.do_thread(t);
1120 }
1121 workers()->threads_do(&cl);
1122 }
1123
1124 void ShenandoahHeap::collect(GCCause::Cause cause) {
1125 control_thread()->request_gc(cause);
1126 }
1127
1128 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1129 //assert(false, "Shouldn't need to do full collections");
1130 }
1131
1132 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1133 Space* sp = heap_region_containing(addr);
1134 if (sp != NULL) {
1135 return sp->block_start(addr);
1136 }
1137 return NULL;
1138 }
1139
1140 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1141 Space* sp = heap_region_containing(addr);
1142 return sp->block_is_obj(addr);
1143 }
1144
1145 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1146 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1147 }
1148
1149 jlong ShenandoahHeap::millis_since_last_gc() {
1150 double v = heuristics()->time_since_last_gc() * 1000;
1151 assert(0 <= v && v <= max_jlong, "value should fit: %f", v);
1152 return (jlong)v;
1153 }
1154
1155 void ShenandoahHeap::prepare_for_verify() {
1156 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1157 make_parsable(false);
1158 }
1159 }
1160
1161 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1162 workers()->print_worker_threads_on(st);
1163 if (ShenandoahStringDedup::is_enabled()) {
1164 ShenandoahStringDedup::print_worker_threads_on(st);
1165 }
1166 }
1167
1168 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1169 workers()->threads_do(tcl);
1170 if (_safepoint_workers != NULL) {
1171 _safepoint_workers->threads_do(tcl);
1172 }
1173 if (ShenandoahStringDedup::is_enabled()) {
1174 ShenandoahStringDedup::threads_do(tcl);
1175 }
1176 }
1177
1178 void ShenandoahHeap::print_tracing_info() const {
1179 LogTarget(Info, gc, stats) lt;
1180 if (lt.is_enabled()) {
1181 ResourceMark rm;
1182 LogStream ls(lt);
1183
1184 phase_timings()->print_on(&ls);
1185
1186 ls.cr();
1187 ls.cr();
1188
1189 shenandoah_policy()->print_gc_stats(&ls);
1190
1191 ls.cr();
1192 ls.cr();
1193
1194 if (ShenandoahPacing) {
1195 pacer()->print_on(&ls);
1196 }
1197
1198 ls.cr();
1199 ls.cr();
1200
1201 if (ShenandoahAllocationTrace) {
1202 assert(alloc_tracker() != NULL, "Must be");
1203 alloc_tracker()->print_on(&ls);
1204 } else {
1205 ls.print_cr(" Allocation tracing is disabled, use -XX:+ShenandoahAllocationTrace to enable.");
1206 }
1207 }
1208 }
1209
1210 void ShenandoahHeap::verify(VerifyOption vo) {
1211 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1212 if (ShenandoahVerify) {
1213 verifier()->verify_generic(vo);
1214 } else {
1215 // TODO: Consider allocating verification bitmaps on demand,
1216 // and turn this on unconditionally.
1217 }
1218 }
1219 }
1220 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1221 return _free_set->capacity();
1222 }
1223
1224 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1225 private:
1226 MarkBitMap* _bitmap;
1227 Stack<oop,mtGC>* _oop_stack;
1228
1229 template <class T>
1230 void do_oop_work(T* p) {
1231 T o = RawAccess<>::oop_load(p);
1232 if (!CompressedOops::is_null(o)) {
1233 oop obj = CompressedOops::decode_not_null(o);
1234 oop fwd = (oop) ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
1235 if (fwd == NULL) {
1236 // There is an odd interaction with VM_HeapWalkOperation, see jvmtiTagMap.cpp.
1237 //
1238 // That operation walks the reachable objects on its own, storing the marking
1239 // wavefront in the object marks. When it is done, it calls the CollectedHeap
1240 // to iterate over all objects to clean up the mess. When it reaches here,
1241 // the Shenandoah fwdptr resolution code encounters the marked objects with
1242 // NULL forwardee. Trying to act on that would crash the VM. Or fail the
1243 // asserts, should we go for resolve_forwarded_pointer(obj).
1244 //
1245 // Therefore, we have to dodge it by doing the raw access to forwardee, and
1246 // assuming the object had no forwardee, if that thing is NULL.
1247 } else {
1248 obj = fwd;
1249 }
1250 assert(oopDesc::is_oop(obj), "must be a valid oop");
1251 if (!_bitmap->is_marked((HeapWord*) obj)) {
1252 _bitmap->mark((HeapWord*) obj);
1253 _oop_stack->push(obj);
1254 }
1255 }
1256 }
1257 public:
1258 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1259 _bitmap(bitmap), _oop_stack(oop_stack) {}
1260 void do_oop(oop* p) { do_oop_work(p); }
1261 void do_oop(narrowOop* p) { do_oop_work(p); }
1262 };
1263
1264 /*
1265 * This is public API, used in preparation of object_iterate().
1266 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1267 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1268 * control, we call SH::make_tlabs_parsable().
1269 */
1270 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1271 // No-op.
1272 }
1273
1274 /*
1275 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1276 *
1277 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1278 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1279 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1280 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1281 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1282 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1283 * wiped the bitmap in preparation for next marking).
1284 *
1285 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1286 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1287 * is allowed to report dead objects, but is not required to do so.
1288 */
1289 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1290 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1291 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1292 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1293 return;
1294 }
1295
1296 // Reset bitmap
1297 _aux_bit_map.clear();
1298
1299 Stack<oop,mtGC> oop_stack;
1300
1301 // First, we process GC roots according to current GC cycle. This populates the work stack with initial objects.
1302 ShenandoahHeapIterationRootScanner rp;
1303 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1304
1305 // If we are unloading classes right now, we should not touch weak roots,
1306 // on the off-chance we would evacuate them and make them live accidentally.
1307 // In other cases, we have to scan all roots.
1308 if (is_evacuation_in_progress() && unload_classes()) {
1309 rp.strong_roots_do(&oops);
1310 } else {
1311 rp.roots_do(&oops);
1312 }
1313
1314 // Work through the oop stack to traverse heap.
1315 while (! oop_stack.is_empty()) {
1316 oop obj = oop_stack.pop();
1317 assert(oopDesc::is_oop(obj), "must be a valid oop");
1318 cl->do_object(obj);
1319 obj->oop_iterate(&oops);
1320 }
1321
1322 assert(oop_stack.is_empty(), "should be empty");
1323
1324 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1325 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1326 }
1327 }
1328
1329 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1330 for (size_t i = 0; i < num_regions(); i++) {
1331 ShenandoahHeapRegion* current = get_region(i);
1332 blk->heap_region_do(current);
1333 }
1334 }
1335
1336 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1337 private:
1338 ShenandoahHeap* const _heap;
1339 ShenandoahHeapRegionClosure* const _blk;
1340
1341 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));
1342 volatile size_t _index;
1343 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
1344
1345 public:
1346 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1347 AbstractGangTask("Parallel Region Task"),
1348 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1349
1350 void work(uint worker_id) {
1351 size_t stride = ShenandoahParallelRegionStride;
1352
1353 size_t max = _heap->num_regions();
1354 while (_index < max) {
1355 size_t cur = Atomic::add(&_index, stride) - stride;
1356 size_t start = cur;
1357 size_t end = MIN2(cur + stride, max);
1358 if (start >= max) break;
1359
1360 for (size_t i = cur; i < end; i++) {
1361 ShenandoahHeapRegion* current = _heap->get_region(i);
1362 _blk->heap_region_do(current);
1363 }
1364 }
1365 }
1366 };
1367
1368 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1369 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1370 if (num_regions() > ShenandoahParallelRegionStride) {
1371 ShenandoahParallelHeapRegionTask task(blk);
1372 workers()->run_task(&task);
1373 } else {
1374 heap_region_iterate(blk);
1375 }
1376 }
1377
1378 class ShenandoahClearLivenessClosure : public ShenandoahHeapRegionClosure {
1379 private:
1380 ShenandoahMarkingContext* const _ctx;
1381 public:
1382 ShenandoahClearLivenessClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1383
1384 void heap_region_do(ShenandoahHeapRegion* r) {
1385 if (r->is_active()) {
1386 r->clear_live_data();
1387 _ctx->capture_top_at_mark_start(r);
1388 } else {
1389 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1390 assert(_ctx->top_at_mark_start(r) == r->top(),
1391 "Region " SIZE_FORMAT " should already have correct TAMS", r->region_number());
1392 }
1393 }
1394
1395 bool is_thread_safe() { return true; }
1396 };
1397
1398 void ShenandoahHeap::op_init_mark() {
1399 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1400 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1401
1402 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1403 assert(!marking_context()->is_complete(), "should not be complete");
1404
1405 if (ShenandoahVerify) {
1406 verifier()->verify_before_concmark();
1407 }
1408
1409 if (VerifyBeforeGC) {
1410 Universe::verify();
1411 }
1412
1413 set_concurrent_mark_in_progress(true);
1414 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1415 {
1416 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1417 make_parsable(true);
1418 }
1419
1420 {
1421 ShenandoahGCPhase phase(ShenandoahPhaseTimings::clear_liveness);
1422 ShenandoahClearLivenessClosure clc;
1423 parallel_heap_region_iterate(&clc);
1424 }
1425
1426 // Make above changes visible to worker threads
1427 OrderAccess::fence();
1428
1429 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1430
1431 if (UseTLAB) {
1432 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1433 resize_tlabs();
1434 }
1435
1436 if (ShenandoahPacing) {
1437 pacer()->setup_for_mark();
1438 }
1439 }
1440
1441 void ShenandoahHeap::op_mark() {
1442 concurrent_mark()->mark_from_roots();
1443 }
1444
1445 class ShenandoahCompleteLivenessClosure : public ShenandoahHeapRegionClosure {
1446 private:
1447 ShenandoahMarkingContext* const _ctx;
1448 public:
1449 ShenandoahCompleteLivenessClosure() : _ctx(ShenandoahHeap::heap()->complete_marking_context()) {}
1450
1451 void heap_region_do(ShenandoahHeapRegion* r) {
1452 if (r->is_active()) {
1453 HeapWord *tams = _ctx->top_at_mark_start(r);
1454 HeapWord *top = r->top();
1455 if (top > tams) {
1456 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1457 }
1458 } else {
1459 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1460 assert(_ctx->top_at_mark_start(r) == r->top(),
1461 "Region " SIZE_FORMAT " should have correct TAMS", r->region_number());
1462 }
1463 }
1464
1465 bool is_thread_safe() { return true; }
1466 };
1467
1468 void ShenandoahHeap::op_final_mark() {
1469 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1470
1471 // It is critical that we
1472 // evacuate roots right after finishing marking, so that we don't
1473 // get unmarked objects in the roots.
1474
1475 if (!cancelled_gc()) {
1476 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1477
1478 // Marking is completed, deactivate SATB barrier
1479 set_concurrent_mark_in_progress(false);
1480 mark_complete_marking_context();
1481
1482 parallel_cleaning(false /* full gc*/);
1483
1484 if (has_forwarded_objects()) {
1485 // Degen may be caused by failed evacuation of roots
1486 if (is_degenerated_gc_in_progress()) {
1487 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
1488 } else {
1489 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::update_roots);
1490 }
1491 set_has_forwarded_objects(false);
1492 }
1493
1494 if (ShenandoahVerify) {
1495 verifier()->verify_roots_no_forwarded();
1496 }
1497 // All allocations past TAMS are implicitly live, adjust the region data.
1498 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1499 {
1500 ShenandoahGCPhase phase(ShenandoahPhaseTimings::complete_liveness);
1501 ShenandoahCompleteLivenessClosure cl;
1502 parallel_heap_region_iterate(&cl);
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 // We are about to select the collection set, make sure it knows about
1512 // current pinning status. Also, this allows trashing more regions that
1513 // now have their pinning status dropped.
1514 {
1515 ShenandoahGCPhase phase(ShenandoahPhaseTimings::sync_pinned);
1516 sync_pinned_region_status();
1517 }
1518
1519 // Trash the collection set left over from previous cycle, if any.
1520 {
1521 ShenandoahGCPhase phase(ShenandoahPhaseTimings::trash_cset);
1522 trash_cset_regions();
1523 }
1524
1525 {
1526 ShenandoahGCPhase phase(ShenandoahPhaseTimings::prepare_evac);
1527
1528 ShenandoahHeapLocker locker(lock());
1529 _collection_set->clear();
1530 _free_set->clear();
1531
1532 heuristics()->choose_collection_set(_collection_set);
1533
1534 _free_set->rebuild();
1535 }
1536
1537 // If collection set has candidates, start evacuation.
1538 // Otherwise, bypass the rest of the cycle.
1539 if (!collection_set()->is_empty()) {
1540 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1541
1542 if (ShenandoahVerify) {
1543 verifier()->verify_before_evacuation();
1544 }
1545
1546 set_evacuation_in_progress(true);
1547 // From here on, we need to update references.
1548 set_has_forwarded_objects(true);
1549
1550 if (!is_degenerated_gc_in_progress()) {
1551 evacuate_and_update_roots();
1552 }
1553
1554 if (ShenandoahPacing) {
1555 pacer()->setup_for_evac();
1556 }
1557
1558 if (ShenandoahVerify) {
1559 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1560 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots);
1561 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots);
1562 verifier()->verify_roots_no_forwarded_except(types);
1563 } else {
1564 verifier()->verify_roots_no_forwarded();
1565 }
1566 verifier()->verify_during_evacuation();
1567 }
1568 } else {
1569 if (ShenandoahVerify) {
1570 verifier()->verify_after_concmark();
1571 }
1572
1573 if (VerifyAfterGC) {
1574 Universe::verify();
1575 }
1576 }
1577
1578 } else {
1579 // If this cycle was updating references, we need to keep the has_forwarded_objects
1580 // flag on, for subsequent phases to deal with it.
1581 concurrent_mark()->cancel();
1582 set_concurrent_mark_in_progress(false);
1583
1584 if (process_references()) {
1585 // Abandon reference processing right away: pre-cleaning must have failed.
1586 ReferenceProcessor *rp = ref_processor();
1587 rp->disable_discovery();
1588 rp->abandon_partial_discovery();
1589 rp->verify_no_references_recorded();
1590 }
1591 }
1592 }
1593
1594 void ShenandoahHeap::op_final_evac() {
1595 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1596
1597 set_evacuation_in_progress(false);
1598
1599 {
1600 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_retire_gclabs);
1601 retire_and_reset_gclabs();
1602 }
1603
1604 if (ShenandoahVerify) {
1605 verifier()->verify_after_evacuation();
1606 }
1607
1608 if (VerifyAfterGC) {
1609 Universe::verify();
1610 }
1611 }
1612
1613 void ShenandoahHeap::op_conc_evac() {
1614 ShenandoahEvacuationTask task(this, _collection_set, true);
1615 workers()->run_task(&task);
1616 }
1617
1618 void ShenandoahHeap::op_stw_evac() {
1619 ShenandoahEvacuationTask task(this, _collection_set, false);
1620 workers()->run_task(&task);
1621 }
1622
1623 void ShenandoahHeap::op_updaterefs() {
1624 update_heap_references(true);
1625 }
1626
1627 void ShenandoahHeap::op_cleanup() {
1628 free_set()->recycle_trash();
1629 }
1630
1631 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask {
1632 private:
1633 ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
1634 ShenandoahWeakRoots<true /*concurrent*/> _weak_roots;
1635 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots;
1636
1637 public:
1638 ShenandoahConcurrentRootsEvacUpdateTask() :
1639 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Roots Task") {
1640 }
1641
1642 void work(uint worker_id) {
1643 ShenandoahEvacOOMScope oom;
1644 {
1645 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
1646 // may race against OopStorage::release() calls.
1647 ShenandoahEvacUpdateOopStorageRootsClosure cl;
1648 _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1649 _weak_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1650 }
1651
1652 {
1653 ShenandoahEvacuateUpdateRootsClosure cl;
1654 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1655 _cld_roots.cld_do(&clds);
1656 }
1657 }
1658 };
1659
1660 void ShenandoahHeap::op_roots() {
1661 if (is_evacuation_in_progress() &&
1662 ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1663 ShenandoahConcurrentRootsEvacUpdateTask task;
1664 workers()->run_task(&task);
1665 }
1666 }
1667
1668 void ShenandoahHeap::op_reset() {
1669 reset_mark_bitmap();
1670 }
1671
1672 void ShenandoahHeap::op_preclean() {
1673 concurrent_mark()->preclean_weak_refs();
1674 }
1675
1676 void ShenandoahHeap::op_init_traversal() {
1677 traversal_gc()->init_traversal_collection();
1678 }
1679
1680 void ShenandoahHeap::op_traversal() {
1681 traversal_gc()->concurrent_traversal_collection();
1682 }
1683
1684 void ShenandoahHeap::op_final_traversal() {
1685 traversal_gc()->final_traversal_collection();
1686 }
1687
1688 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1689 ShenandoahMetricsSnapshot metrics;
1690 metrics.snap_before();
1691
1692 full_gc()->do_it(cause);
1693 if (UseTLAB) {
1694 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs);
1695 resize_all_tlabs();
1696 }
1697
1698 metrics.snap_after();
1699
1700 if (metrics.is_good_progress()) {
1701 _progress_last_gc.set();
1702 } else {
1703 // Nothing to do. Tell the allocation path that we have failed to make
1704 // progress, and it can finally fail.
1705 _progress_last_gc.unset();
1706 }
1707 }
1708
1709 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1710 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1711 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1712 // some phase, we have to upgrade the Degenerate GC to Full GC.
1713
1714 clear_cancelled_gc();
1715
1716 ShenandoahMetricsSnapshot metrics;
1717 metrics.snap_before();
1718
1719 switch (point) {
1720 case _degenerated_traversal:
1721 {
1722 // Drop the collection set. Note: this leaves some already forwarded objects
1723 // behind, which may be problematic, see comments for ShenandoahEvacAssist
1724 // workarounds in ShenandoahTraversalHeuristics.
1725
1726 ShenandoahHeapLocker locker(lock());
1727 collection_set()->clear_current_index();
1728 for (size_t i = 0; i < collection_set()->count(); i++) {
1729 ShenandoahHeapRegion* r = collection_set()->next();
1730 r->make_regular_bypass();
1731 }
1732 collection_set()->clear();
1733 }
1734 op_final_traversal();
1735 op_cleanup();
1736 return;
1737
1738 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1739 // but enters it at different points, depending on which concurrent phase had
1740 // degenerated.
1741
1742 case _degenerated_outside_cycle:
1743 // We have degenerated from outside the cycle, which means something is bad with
1744 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1745 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1746 // we can do the most aggressive degen cycle, which includes processing references and
1747 // class unloading, unless those features are explicitly disabled.
1748 //
1749 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1750 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1751 set_process_references(heuristics()->can_process_references());
1752 set_unload_classes(heuristics()->can_unload_classes());
1753
1754 if (is_traversal_mode()) {
1755 // Not possible to degenerate from here, upgrade to Full GC right away.
1756 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1757 op_degenerated_fail();
1758 return;
1759 }
1760
1761 op_reset();
1762
1763 op_init_mark();
1764 if (cancelled_gc()) {
1765 op_degenerated_fail();
1766 return;
1767 }
1768
1769 case _degenerated_mark:
1770 op_final_mark();
1771 if (cancelled_gc()) {
1772 op_degenerated_fail();
1773 return;
1774 }
1775
1776 op_cleanup();
1777
1778 case _degenerated_evac:
1779 // If heuristics thinks we should do the cycle, this flag would be set,
1780 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
1781 if (is_evacuation_in_progress()) {
1782
1783 // Degeneration under oom-evac protocol might have left some objects in
1784 // collection set un-evacuated. Restart evacuation from the beginning to
1785 // capture all objects. For all the objects that are already evacuated,
1786 // it would be a simple check, which is supposed to be fast. This is also
1787 // safe to do even without degeneration, as CSet iterator is at beginning
1788 // in preparation for evacuation anyway.
1789 //
1790 // Before doing that, we need to make sure we never had any cset-pinned
1791 // regions. This may happen if allocation failure happened when evacuating
1792 // the about-to-be-pinned object, oom-evac protocol left the object in
1793 // the collection set, and then the pin reached the cset region. If we continue
1794 // the cycle here, we would trash the cset and alive objects in it. To avoid
1795 // it, we fail degeneration right away and slide into Full GC to recover.
1796
1797 {
1798 sync_pinned_region_status();
1799 collection_set()->clear_current_index();
1800
1801 ShenandoahHeapRegion* r;
1802 while ((r = collection_set()->next()) != NULL) {
1803 if (r->is_pinned()) {
1804 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1805 op_degenerated_fail();
1806 return;
1807 }
1808 }
1809
1810 collection_set()->clear_current_index();
1811 }
1812
1813 op_stw_evac();
1814 if (cancelled_gc()) {
1815 op_degenerated_fail();
1816 return;
1817 }
1818 }
1819
1820 // If heuristics thinks we should do the cycle, this flag would be set,
1821 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
1822 if (has_forwarded_objects()) {
1823 op_init_updaterefs();
1824 if (cancelled_gc()) {
1825 op_degenerated_fail();
1826 return;
1827 }
1828 }
1829
1830 case _degenerated_updaterefs:
1831 if (has_forwarded_objects()) {
1832 op_final_updaterefs();
1833 if (cancelled_gc()) {
1834 op_degenerated_fail();
1835 return;
1836 }
1837 }
1838
1839 op_cleanup();
1840 break;
1841
1842 default:
1843 ShouldNotReachHere();
1844 }
1845
1846 if (ShenandoahVerify) {
1847 verifier()->verify_after_degenerated();
1848 }
1849
1850 if (VerifyAfterGC) {
1851 Universe::verify();
1852 }
1853
1854 metrics.snap_after();
1855
1856 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
1857 // because that probably means the heap is overloaded and/or fragmented.
1858 if (!metrics.is_good_progress()) {
1859 _progress_last_gc.unset();
1860 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1861 op_degenerated_futile();
1862 } else {
1863 _progress_last_gc.set();
1864 }
1865 }
1866
1867 void ShenandoahHeap::op_degenerated_fail() {
1868 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
1869 shenandoah_policy()->record_degenerated_upgrade_to_full();
1870 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1871 }
1872
1873 void ShenandoahHeap::op_degenerated_futile() {
1874 shenandoah_policy()->record_degenerated_upgrade_to_full();
1875 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1876 }
1877
1878 void ShenandoahHeap::force_satb_flush_all_threads() {
1879 if (!is_concurrent_mark_in_progress() && !is_concurrent_traversal_in_progress()) {
1880 // No need to flush SATBs
1881 return;
1882 }
1883
1884 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1885 ShenandoahThreadLocalData::set_force_satb_flush(t, true);
1886 }
1887 // The threads are not "acquiring" their thread-local data, but it does not
1888 // hurt to "release" the updates here anyway.
1889 OrderAccess::fence();
1890 }
1891
1892 void ShenandoahHeap::set_gc_state_all_threads(char state) {
1893 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1894 ShenandoahThreadLocalData::set_gc_state(t, state);
1895 }
1896 }
1897
1898 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1899 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1900 _gc_state.set_cond(mask, value);
1901 set_gc_state_all_threads(_gc_state.raw_value());
1902 }
1903
1904 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1905 if (has_forwarded_objects()) {
1906 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
1907 } else {
1908 set_gc_state_mask(MARKING, in_progress);
1909 }
1910 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1911 }
1912
1913 void ShenandoahHeap::set_concurrent_traversal_in_progress(bool in_progress) {
1914 set_gc_state_mask(TRAVERSAL, in_progress);
1915 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1916 }
1917
1918 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1919 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1920 set_gc_state_mask(EVACUATION, in_progress);
1921 }
1922
1923 void ShenandoahHeap::ref_processing_init() {
1924 assert(_max_workers > 0, "Sanity");
1925
1926 _ref_processor =
1927 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
1928 ParallelRefProcEnabled, // MT processing
1929 _max_workers, // Degree of MT processing
1930 true, // MT discovery
1931 _max_workers, // Degree of MT discovery
1932 false, // Reference discovery is not atomic
1933 NULL, // No closure, should be installed before use
1934 true); // Scale worker threads
1935
1936 shenandoah_assert_rp_isalive_not_installed();
1937 }
1938
1939 GCTracer* ShenandoahHeap::tracer() {
1940 return shenandoah_policy()->tracer();
1941 }
1942
1943 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1944 return _free_set->used();
1945 }
1946
1947 bool ShenandoahHeap::try_cancel_gc() {
1948 while (true) {
1949 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1950 if (prev == CANCELLABLE) return true;
1951 else if (prev == CANCELLED) return false;
1952 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
1953 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
1954 if (Thread::current()->is_Java_thread()) {
1955 // We need to provide a safepoint here, otherwise we might
1956 // spin forever if a SP is pending.
1957 ThreadBlockInVM sp(JavaThread::current());
1958 SpinPause();
1959 }
1960 }
1961 }
1962
1963 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1964 if (try_cancel_gc()) {
1965 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1966 log_info(gc)("%s", msg.buffer());
1967 Events::log(Thread::current(), "%s", msg.buffer());
1968 }
1969 }
1970
1971 uint ShenandoahHeap::max_workers() {
1972 return _max_workers;
1973 }
1974
1975 void ShenandoahHeap::stop() {
1976 // The shutdown sequence should be able to terminate when GC is running.
1977
1978 // Step 0. Notify policy to disable event recording.
1979 _shenandoah_policy->record_shutdown();
1980
1981 // Step 1. Notify control thread that we are in shutdown.
1982 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1983 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1984 control_thread()->prepare_for_graceful_shutdown();
1985
1986 // Step 2. Notify GC workers that we are cancelling GC.
1987 cancel_gc(GCCause::_shenandoah_stop_vm);
1988
1989 // Step 3. Wait until GC worker exits normally.
1990 control_thread()->stop();
1991
1992 // Step 4. Stop String Dedup thread if it is active
1993 if (ShenandoahStringDedup::is_enabled()) {
1994 ShenandoahStringDedup::stop();
1995 }
1996 }
1997
1998 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
1999 if (!unload_classes()) return;
2000 bool purged_class;
2001
2002 // Unload classes and purge SystemDictionary.
2003 {
2004 ShenandoahGCPhase phase(full_gc ?
2005 ShenandoahPhaseTimings::full_gc_purge_class_unload :
2006 ShenandoahPhaseTimings::purge_class_unload);
2007 purged_class = SystemDictionary::do_unloading(gc_timer());
2008 }
2009
2010 {
2011 ShenandoahGCPhase phase(full_gc ?
2012 ShenandoahPhaseTimings::full_gc_purge_par :
2013 ShenandoahPhaseTimings::purge_par);
2014 ShenandoahIsAliveSelector is_alive;
2015 uint num_workers = _workers->active_workers();
2016 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
2017 _workers->run_task(&unlink_task);
2018 }
2019
2020 {
2021 ShenandoahGCPhase phase(full_gc ?
2022 ShenandoahPhaseTimings::full_gc_purge_cldg :
2023 ShenandoahPhaseTimings::purge_cldg);
2024 ClassLoaderDataGraph::purge();
2025 }
2026 // Resize and verify metaspace
2027 MetaspaceGC::compute_new_size();
2028 MetaspaceUtils::verify_metrics();
2029 }
2030
2031 // Process leftover weak oops: update them, if needed or assert they do not
2032 // need updating otherwise.
2033 // Weak processor API requires us to visit the oops, even if we are not doing
2034 // anything to them.
2035 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
2036 ShenandoahGCPhase root_phase(full_gc ?
2037 ShenandoahPhaseTimings::full_gc_purge :
2038 ShenandoahPhaseTimings::purge);
2039 uint num_workers = _workers->active_workers();
2040 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
2041 ShenandoahPhaseTimings::full_gc_purge_par :
2042 ShenandoahPhaseTimings::purge_par;
2043 // Cleanup weak roots
2044 ShenandoahGCPhase phase(timing_phase);
2045 if (has_forwarded_objects()) {
2046 if (is_traversal_mode()) {
2047 ShenandoahForwardedIsAliveClosure is_alive;
2048 ShenandoahTraversalUpdateRefsClosure keep_alive;
2049 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahTraversalUpdateRefsClosure>
2050 cleaning_task(&is_alive, &keep_alive, num_workers);
2051 _workers->run_task(&cleaning_task);
2052 } else {
2053 ShenandoahForwardedIsAliveClosure is_alive;
2054 ShenandoahUpdateRefsClosure keep_alive;
2055 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2056 cleaning_task(&is_alive, &keep_alive, num_workers);
2057 _workers->run_task(&cleaning_task);
2058 }
2059 } else {
2060 ShenandoahIsAliveClosure is_alive;
2061 #ifdef ASSERT
2062 ShenandoahAssertNotForwardedClosure verify_cl;
2063 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2064 cleaning_task(&is_alive, &verify_cl, num_workers);
2065 #else
2066 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2067 cleaning_task(&is_alive, &do_nothing_cl, num_workers);
2068 #endif
2069 _workers->run_task(&cleaning_task);
2070 }
2071 }
2072
2073 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2074 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2075 stw_process_weak_roots(full_gc);
2076 stw_unload_classes(full_gc);
2077 }
2078
2079 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2080 if (is_traversal_mode()) {
2081 set_gc_state_mask(HAS_FORWARDED | UPDATEREFS, cond);
2082 } else {
2083 set_gc_state_mask(HAS_FORWARDED, cond);
2084 }
2085
2086 }
2087
2088 void ShenandoahHeap::set_process_references(bool pr) {
2089 _process_references.set_cond(pr);
2090 }
2091
2092 void ShenandoahHeap::set_unload_classes(bool uc) {
2093 _unload_classes.set_cond(uc);
2094 }
2095
2096 bool ShenandoahHeap::process_references() const {
2097 return _process_references.is_set();
2098 }
2099
2100 bool ShenandoahHeap::unload_classes() const {
2101 return _unload_classes.is_set();
2102 }
2103
2104 address ShenandoahHeap::in_cset_fast_test_addr() {
2105 ShenandoahHeap* heap = ShenandoahHeap::heap();
2106 assert(heap->collection_set() != NULL, "Sanity");
2107 return (address) heap->collection_set()->biased_map_address();
2108 }
2109
2110 address ShenandoahHeap::cancelled_gc_addr() {
2111 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
2112 }
2113
2114 address ShenandoahHeap::gc_state_addr() {
2115 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2116 }
2117
2118 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2119 return Atomic::load_acquire(&_bytes_allocated_since_gc_start);
2120 }
2121
2122 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2123 Atomic::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2124 }
2125
2126 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2127 _degenerated_gc_in_progress.set_cond(in_progress);
2128 }
2129
2130 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2131 _full_gc_in_progress.set_cond(in_progress);
2132 }
2133
2134 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2135 assert (is_full_gc_in_progress(), "should be");
2136 _full_gc_move_in_progress.set_cond(in_progress);
2137 }
2138
2139 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2140 set_gc_state_mask(UPDATEREFS, in_progress);
2141 }
2142
2143 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2144 ShenandoahCodeRoots::add_nmethod(nm);
2145 }
2146
2147 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2148 ShenandoahCodeRoots::remove_nmethod(nm);
2149 }
2150
2151 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2152 heap_region_containing(o)->record_pin();
2153 return o;
2154 }
2155
2156 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2157 heap_region_containing(o)->record_unpin();
2158 }
2159
2160 void ShenandoahHeap::sync_pinned_region_status() {
2161 ShenandoahHeapLocker locker(lock());
2162
2163 for (size_t i = 0; i < num_regions(); i++) {
2164 ShenandoahHeapRegion *r = get_region(i);
2165 if (r->is_active()) {
2166 if (r->is_pinned()) {
2167 if (r->pin_count() == 0) {
2168 r->make_unpinned();
2169 }
2170 } else {
2171 if (r->pin_count() > 0) {
2172 r->make_pinned();
2173 }
2174 }
2175 }
2176 }
2177
2178 assert_pinned_region_status();
2179 }
2180
2181 #ifdef ASSERT
2182 void ShenandoahHeap::assert_pinned_region_status() {
2183 for (size_t i = 0; i < num_regions(); i++) {
2184 ShenandoahHeapRegion* r = get_region(i);
2185 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2186 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2187 }
2188 }
2189 #endif
2190
2191 GCTimer* ShenandoahHeap::gc_timer() const {
2192 return _gc_timer;
2193 }
2194
2195 #ifdef ASSERT
2196 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2197 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2198
2199 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2200 if (UseDynamicNumberOfGCThreads ||
2201 (FLAG_IS_DEFAULT(ParallelGCThreads) && ForceDynamicNumberOfGCThreads)) {
2202 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2203 } else {
2204 // Use ParallelGCThreads inside safepoints
2205 assert(nworkers == ParallelGCThreads, "Use ParalleGCThreads within safepoints");
2206 }
2207 } else {
2208 if (UseDynamicNumberOfGCThreads ||
2209 (FLAG_IS_DEFAULT(ConcGCThreads) && ForceDynamicNumberOfGCThreads)) {
2210 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2211 } else {
2212 // Use ConcGCThreads outside safepoints
2213 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2214 }
2215 }
2216 }
2217 #endif
2218
2219 ShenandoahVerifier* ShenandoahHeap::verifier() {
2220 guarantee(ShenandoahVerify, "Should be enabled");
2221 assert (_verifier != NULL, "sanity");
2222 return _verifier;
2223 }
2224
2225 template<class T>
2226 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2227 private:
2228 T cl;
2229 ShenandoahHeap* _heap;
2230 ShenandoahRegionIterator* _regions;
2231 bool _concurrent;
2232 public:
2233 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2234 AbstractGangTask("Concurrent Update References Task"),
2235 cl(T()),
2236 _heap(ShenandoahHeap::heap()),
2237 _regions(regions),
2238 _concurrent(concurrent) {
2239 }
2240
2241 void work(uint worker_id) {
2242 if (_concurrent) {
2243 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2244 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2245 do_work();
2246 } else {
2247 ShenandoahParallelWorkerSession worker_session(worker_id);
2248 do_work();
2249 }
2250 }
2251
2252 private:
2253 void do_work() {
2254 ShenandoahHeapRegion* r = _regions->next();
2255 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2256 while (r != NULL) {
2257 HeapWord* top_at_start_ur = r->concurrent_iteration_safe_limit();
2258 assert (top_at_start_ur >= r->bottom(), "sanity");
2259 if (r->is_active() && !r->is_cset()) {
2260 _heap->marked_object_oop_iterate(r, &cl, top_at_start_ur);
2261 }
2262 if (ShenandoahPacing) {
2263 _heap->pacer()->report_updaterefs(pointer_delta(top_at_start_ur, r->bottom()));
2264 }
2265 if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
2266 return;
2267 }
2268 r = _regions->next();
2269 }
2270 }
2271 };
2272
2273 void ShenandoahHeap::update_heap_references(bool concurrent) {
2274 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
2275 workers()->run_task(&task);
2276 }
2277
2278 void ShenandoahHeap::op_init_updaterefs() {
2279 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2280
2281 set_evacuation_in_progress(false);
2282
2283 {
2284 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_retire_gclabs);
2285 retire_and_reset_gclabs();
2286 }
2287
2288 if (ShenandoahVerify) {
2289 if (!is_degenerated_gc_in_progress()) {
2290 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots);
2291 }
2292 verifier()->verify_before_updaterefs();
2293 }
2294
2295 set_update_refs_in_progress(true);
2296
2297 {
2298 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_prepare);
2299
2300 make_parsable(true);
2301 for (uint i = 0; i < num_regions(); i++) {
2302 ShenandoahHeapRegion* r = get_region(i);
2303 r->set_concurrent_iteration_safe_limit(r->top());
2304 }
2305
2306 // Reset iterator.
2307 _update_refs_iterator.reset();
2308 }
2309
2310 if (ShenandoahPacing) {
2311 pacer()->setup_for_updaterefs();
2312 }
2313 }
2314
2315 void ShenandoahHeap::op_final_updaterefs() {
2316 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2317
2318 // Check if there is left-over work, and finish it
2319 if (_update_refs_iterator.has_next()) {
2320 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2321
2322 // Finish updating references where we left off.
2323 clear_cancelled_gc();
2324 update_heap_references(false);
2325 }
2326
2327 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2328 // everything. On degenerated paths, cancelled gc would not be set anyway.
2329 if (cancelled_gc()) {
2330 clear_cancelled_gc();
2331 }
2332 assert(!cancelled_gc(), "Should have been done right before");
2333
2334 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2335 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots);
2336 }
2337
2338 if (is_degenerated_gc_in_progress()) {
2339 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2340 } else {
2341 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2342 }
2343
2344 // Has to be done before cset is clear
2345 if (ShenandoahVerify) {
2346 verifier()->verify_roots_in_to_space();
2347 }
2348
2349 // Drop unnecessary "pinned" state from regions that does not have CP marks
2350 // anymore, as this would allow trashing them below.
2351 {
2352 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_sync_pinned);
2353 sync_pinned_region_status();
2354 }
2355
2356 {
2357 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2358 trash_cset_regions();
2359 }
2360
2361 set_has_forwarded_objects(false);
2362 set_update_refs_in_progress(false);
2363
2364 if (ShenandoahVerify) {
2365 verifier()->verify_after_updaterefs();
2366 }
2367
2368 if (VerifyAfterGC) {
2369 Universe::verify();
2370 }
2371
2372 {
2373 ShenandoahHeapLocker locker(lock());
2374 _free_set->rebuild();
2375 }
2376 }
2377
2378 #ifdef ASSERT
2379 void ShenandoahHeap::assert_heaplock_owned_by_current_thread() {
2380 _lock.assert_owned_by_current_thread();
2381 }
2382
2383 void ShenandoahHeap::assert_heaplock_not_owned_by_current_thread() {
2384 _lock.assert_not_owned_by_current_thread();
2385 }
2386
2387 void ShenandoahHeap::assert_heaplock_or_safepoint() {
2388 _lock.assert_owned_by_current_thread_or_safepoint();
2389 }
2390 #endif
2391
2392 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2393 print_on(st);
2394 print_heap_regions_on(st);
2395 }
2396
2397 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2398 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2399
2400 size_t regions_from = _bitmap_regions_per_slice * slice;
2401 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2402 for (size_t g = regions_from; g < regions_to; g++) {
2403 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2404 if (skip_self && g == r->region_number()) continue;
2405 if (get_region(g)->is_committed()) {
2406 return true;
2407 }
2408 }
2409 return false;
2410 }
2411
2412 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2413 assert_heaplock_owned_by_current_thread();
2414
2415 // Bitmaps in special regions do not need commits
2416 if (_bitmap_region_special) {
2417 return true;
2418 }
2419
2420 if (is_bitmap_slice_committed(r, true)) {
2421 // Some other region from the group is already committed, meaning the bitmap
2422 // slice is already committed, we exit right away.
2423 return true;
2424 }
2425
2426 // Commit the bitmap slice:
2427 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2428 size_t off = _bitmap_bytes_per_slice * slice;
2429 size_t len = _bitmap_bytes_per_slice;
2430 if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) {
2431 return false;
2432 }
2433 return true;
2434 }
2435
2436 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2437 assert_heaplock_owned_by_current_thread();
2438
2439 // Bitmaps in special regions do not need uncommits
2440 if (_bitmap_region_special) {
2441 return true;
2442 }
2443
2444 if (is_bitmap_slice_committed(r, true)) {
2445 // Some other region from the group is still committed, meaning the bitmap
2446 // slice is should stay committed, exit right away.
2447 return true;
2448 }
2449
2450 // Uncommit the bitmap slice:
2451 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2452 size_t off = _bitmap_bytes_per_slice * slice;
2453 size_t len = _bitmap_bytes_per_slice;
2454 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2455 return false;
2456 }
2457 return true;
2458 }
2459
2460 void ShenandoahHeap::safepoint_synchronize_begin() {
2461 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2462 SuspendibleThreadSet::synchronize();
2463 }
2464 }
2465
2466 void ShenandoahHeap::safepoint_synchronize_end() {
2467 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2468 SuspendibleThreadSet::desynchronize();
2469 }
2470 }
2471
2472 void ShenandoahHeap::vmop_entry_init_mark() {
2473 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2474 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2475 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
2476
2477 try_inject_alloc_failure();
2478 VM_ShenandoahInitMark op;
2479 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2480 }
2481
2482 void ShenandoahHeap::vmop_entry_final_mark() {
2483 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2484 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2485 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
2486
2487 try_inject_alloc_failure();
2488 VM_ShenandoahFinalMarkStartEvac op;
2489 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2490 }
2491
2492 void ShenandoahHeap::vmop_entry_final_evac() {
2493 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2494 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2495 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_gross);
2496
2497 VM_ShenandoahFinalEvac op;
2498 VMThread::execute(&op); // jump to entry_final_evac under safepoint
2499 }
2500
2501 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2502 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2503 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2504 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
2505
2506 try_inject_alloc_failure();
2507 VM_ShenandoahInitUpdateRefs op;
2508 VMThread::execute(&op);
2509 }
2510
2511 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2512 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2513 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2514 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
2515
2516 try_inject_alloc_failure();
2517 VM_ShenandoahFinalUpdateRefs op;
2518 VMThread::execute(&op);
2519 }
2520
2521 void ShenandoahHeap::vmop_entry_init_traversal() {
2522 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2523 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2524 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc_gross);
2525
2526 try_inject_alloc_failure();
2527 VM_ShenandoahInitTraversalGC op;
2528 VMThread::execute(&op);
2529 }
2530
2531 void ShenandoahHeap::vmop_entry_final_traversal() {
2532 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2533 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2534 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc_gross);
2535
2536 try_inject_alloc_failure();
2537 VM_ShenandoahFinalTraversalGC op;
2538 VMThread::execute(&op);
2539 }
2540
2541 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2542 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2543 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2544 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
2545
2546 try_inject_alloc_failure();
2547 VM_ShenandoahFullGC op(cause);
2548 VMThread::execute(&op);
2549 }
2550
2551 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2552 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2553 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2554 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
2555
2556 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2557 VMThread::execute(°enerated_gc);
2558 }
2559
2560 void ShenandoahHeap::entry_init_mark() {
2561 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2562 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
2563 const char* msg = init_mark_event_message();
2564 GCTraceTime(Info, gc) time(msg, gc_timer());
2565 EventMark em("%s", msg);
2566
2567 ShenandoahWorkerScope scope(workers(),
2568 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2569 "init marking");
2570
2571 op_init_mark();
2572 }
2573
2574 void ShenandoahHeap::entry_final_mark() {
2575 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2576 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
2577 const char* msg = final_mark_event_message();
2578 GCTraceTime(Info, gc) time(msg, gc_timer());
2579 EventMark em("%s", msg);
2580
2581 ShenandoahWorkerScope scope(workers(),
2582 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2583 "final marking");
2584
2585 op_final_mark();
2586 }
2587
2588 void ShenandoahHeap::entry_final_evac() {
2589 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2590 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac);
2591 static const char* msg = "Pause Final Evac";
2592 GCTraceTime(Info, gc) time(msg, gc_timer());
2593 EventMark em("%s", msg);
2594
2595 op_final_evac();
2596 }
2597
2598 void ShenandoahHeap::entry_init_updaterefs() {
2599 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2600 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
2601
2602 static const char* msg = "Pause Init Update Refs";
2603 GCTraceTime(Info, gc) time(msg, gc_timer());
2604 EventMark em("%s", msg);
2605
2606 // No workers used in this phase, no setup required
2607
2608 op_init_updaterefs();
2609 }
2610
2611 void ShenandoahHeap::entry_final_updaterefs() {
2612 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2613 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
2614
2615 static const char* msg = "Pause Final Update Refs";
2616 GCTraceTime(Info, gc) time(msg, gc_timer());
2617 EventMark em("%s", msg);
2618
2619 ShenandoahWorkerScope scope(workers(),
2620 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2621 "final reference update");
2622
2623 op_final_updaterefs();
2624 }
2625
2626 void ShenandoahHeap::entry_init_traversal() {
2627 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2628 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc);
2629
2630 static const char* msg = "Pause Init Traversal";
2631 GCTraceTime(Info, gc) time(msg, gc_timer());
2632 EventMark em("%s", msg);
2633
2634 ShenandoahWorkerScope scope(workers(),
2635 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2636 "init traversal");
2637
2638 op_init_traversal();
2639 }
2640
2641 void ShenandoahHeap::entry_final_traversal() {
2642 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2643 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc);
2644
2645 static const char* msg = "Pause Final Traversal";
2646 GCTraceTime(Info, gc) time(msg, gc_timer());
2647 EventMark em("%s", msg);
2648
2649 ShenandoahWorkerScope scope(workers(),
2650 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2651 "final traversal");
2652
2653 op_final_traversal();
2654 }
2655
2656 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2657 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2658 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
2659
2660 static const char* msg = "Pause Full";
2661 GCTraceTime(Info, gc) time(msg, gc_timer(), cause, true);
2662 EventMark em("%s", msg);
2663
2664 ShenandoahWorkerScope scope(workers(),
2665 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2666 "full gc");
2667
2668 op_full(cause);
2669 }
2670
2671 void ShenandoahHeap::entry_degenerated(int point) {
2672 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2673 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
2674
2675 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2676 const char* msg = degen_event_message(dpoint);
2677 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2678 EventMark em("%s", msg);
2679
2680 ShenandoahWorkerScope scope(workers(),
2681 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2682 "stw degenerated gc");
2683
2684 set_degenerated_gc_in_progress(true);
2685 op_degenerated(dpoint);
2686 set_degenerated_gc_in_progress(false);
2687 }
2688
2689 void ShenandoahHeap::entry_mark() {
2690 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2691
2692 const char* msg = conc_mark_event_message();
2693 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2694 EventMark em("%s", msg);
2695
2696 ShenandoahWorkerScope scope(workers(),
2697 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2698 "concurrent marking");
2699
2700 try_inject_alloc_failure();
2701 op_mark();
2702 }
2703
2704 void ShenandoahHeap::entry_evac() {
2705 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
2706 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2707
2708 static const char* msg = "Concurrent evacuation";
2709 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2710 EventMark em("%s", msg);
2711
2712 ShenandoahWorkerScope scope(workers(),
2713 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2714 "concurrent evacuation");
2715
2716 try_inject_alloc_failure();
2717 op_conc_evac();
2718 }
2719
2720 void ShenandoahHeap::entry_updaterefs() {
2721 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
2722
2723 static const char* msg = "Concurrent update references";
2724 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2725 EventMark em("%s", msg);
2726
2727 ShenandoahWorkerScope scope(workers(),
2728 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2729 "concurrent reference update");
2730
2731 try_inject_alloc_failure();
2732 op_updaterefs();
2733 }
2734
2735 void ShenandoahHeap::entry_roots() {
2736 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_roots);
2737
2738 static const char* msg = "Concurrent roots processing";
2739 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2740 EventMark em("%s", msg);
2741
2742 ShenandoahWorkerScope scope(workers(),
2743 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2744 "concurrent root processing");
2745
2746 try_inject_alloc_failure();
2747 op_roots();
2748 }
2749
2750 void ShenandoahHeap::entry_cleanup() {
2751 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup);
2752
2753 static const char* msg = "Concurrent cleanup";
2754 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2755 EventMark em("%s", msg);
2756
2757 // This phase does not use workers, no need for setup
2758
2759 try_inject_alloc_failure();
2760 op_cleanup();
2761 }
2762
2763 void ShenandoahHeap::entry_reset() {
2764 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset);
2765
2766 static const char* msg = "Concurrent reset";
2767 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2768 EventMark em("%s", msg);
2769
2770 ShenandoahWorkerScope scope(workers(),
2771 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2772 "concurrent reset");
2773
2774 try_inject_alloc_failure();
2775 op_reset();
2776 }
2777
2778 void ShenandoahHeap::entry_preclean() {
2779 if (ShenandoahPreclean && process_references()) {
2780 static const char* msg = "Concurrent precleaning";
2781 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2782 EventMark em("%s", msg);
2783
2784 ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
2785
2786 ShenandoahWorkerScope scope(workers(),
2787 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2788 "concurrent preclean",
2789 /* check_workers = */ false);
2790
2791 try_inject_alloc_failure();
2792 op_preclean();
2793 }
2794 }
2795
2796 void ShenandoahHeap::entry_traversal() {
2797 static const char* msg = "Concurrent traversal";
2798 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2799 EventMark em("%s", msg);
2800
2801 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2802
2803 ShenandoahWorkerScope scope(workers(),
2804 ShenandoahWorkerPolicy::calc_workers_for_conc_traversal(),
2805 "concurrent traversal");
2806
2807 try_inject_alloc_failure();
2808 op_traversal();
2809 }
2810
2811 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2812 static const char *msg = "Concurrent uncommit";
2813 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2814 EventMark em("%s", msg);
2815
2816 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit);
2817
2818 op_uncommit(shrink_before);
2819 }
2820
2821 void ShenandoahHeap::try_inject_alloc_failure() {
2822 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2823 _inject_alloc_failure.set();
2824 os::naked_short_sleep(1);
2825 if (cancelled_gc()) {
2826 log_info(gc)("Allocation failure was successfully injected");
2827 }
2828 }
2829 }
2830
2831 bool ShenandoahHeap::should_inject_alloc_failure() {
2832 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2833 }
2834
2835 void ShenandoahHeap::initialize_serviceability() {
2836 _memory_pool = new ShenandoahMemoryPool(this);
2837 _cycle_memory_manager.add_pool(_memory_pool);
2838 _stw_memory_manager.add_pool(_memory_pool);
2839 }
2840
2841 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2842 GrowableArray<GCMemoryManager*> memory_managers(2);
2843 memory_managers.append(&_cycle_memory_manager);
2844 memory_managers.append(&_stw_memory_manager);
2845 return memory_managers;
2846 }
2847
2848 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2849 GrowableArray<MemoryPool*> memory_pools(1);
2850 memory_pools.append(_memory_pool);
2851 return memory_pools;
2852 }
2853
2854 MemoryUsage ShenandoahHeap::memory_usage() {
2855 return _memory_pool->get_memory_usage();
2856 }
2857
2858 void ShenandoahHeap::enter_evacuation() {
2859 _oom_evac_handler.enter_evacuation();
2860 }
2861
2862 void ShenandoahHeap::leave_evacuation() {
2863 _oom_evac_handler.leave_evacuation();
2864 }
2865
2866 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2867 _heap(ShenandoahHeap::heap()),
2868 _index(0) {}
2869
2870 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2871 _heap(heap),
2872 _index(0) {}
2873
2874 void ShenandoahRegionIterator::reset() {
2875 _index = 0;
2876 }
2877
2878 bool ShenandoahRegionIterator::has_next() const {
2879 return _index < _heap->num_regions();
2880 }
2881
2882 char ShenandoahHeap::gc_state() const {
2883 return _gc_state.raw_value();
2884 }
2885
2886 void ShenandoahHeap::deduplicate_string(oop str) {
2887 assert(java_lang_String::is_instance(str), "invariant");
2888
2889 if (ShenandoahStringDedup::is_enabled()) {
2890 ShenandoahStringDedup::deduplicate(str);
2891 }
2892 }
2893
2894 const char* ShenandoahHeap::init_mark_event_message() const {
2895 bool update_refs = has_forwarded_objects();
2896 bool proc_refs = process_references();
2897 bool unload_cls = unload_classes();
2898
2899 if (update_refs && proc_refs && unload_cls) {
2900 return "Pause Init Mark (update refs) (process weakrefs) (unload classes)";
2901 } else if (update_refs && proc_refs) {
2902 return "Pause Init Mark (update refs) (process weakrefs)";
2903 } else if (update_refs && unload_cls) {
2904 return "Pause Init Mark (update refs) (unload classes)";
2905 } else if (proc_refs && unload_cls) {
2906 return "Pause Init Mark (process weakrefs) (unload classes)";
2907 } else if (update_refs) {
2908 return "Pause Init Mark (update refs)";
2909 } else if (proc_refs) {
2910 return "Pause Init Mark (process weakrefs)";
2911 } else if (unload_cls) {
2912 return "Pause Init Mark (unload classes)";
2913 } else {
2914 return "Pause Init Mark";
2915 }
2916 }
2917
2918 const char* ShenandoahHeap::final_mark_event_message() const {
2919 bool update_refs = has_forwarded_objects();
2920 bool proc_refs = process_references();
2921 bool unload_cls = unload_classes();
2922
2923 if (update_refs && proc_refs && unload_cls) {
2924 return "Pause Final Mark (update refs) (process weakrefs) (unload classes)";
2925 } else if (update_refs && proc_refs) {
2926 return "Pause Final Mark (update refs) (process weakrefs)";
2927 } else if (update_refs && unload_cls) {
2928 return "Pause Final Mark (update refs) (unload classes)";
2929 } else if (proc_refs && unload_cls) {
2930 return "Pause Final Mark (process weakrefs) (unload classes)";
2931 } else if (update_refs) {
2932 return "Pause Final Mark (update refs)";
2933 } else if (proc_refs) {
2934 return "Pause Final Mark (process weakrefs)";
2935 } else if (unload_cls) {
2936 return "Pause Final Mark (unload classes)";
2937 } else {
2938 return "Pause Final Mark";
2939 }
2940 }
2941
2942 const char* ShenandoahHeap::conc_mark_event_message() const {
2943 bool update_refs = has_forwarded_objects();
2944 bool proc_refs = process_references();
2945 bool unload_cls = unload_classes();
2946
2947 if (update_refs && proc_refs && unload_cls) {
2948 return "Concurrent marking (update refs) (process weakrefs) (unload classes)";
2949 } else if (update_refs && proc_refs) {
2950 return "Concurrent marking (update refs) (process weakrefs)";
2951 } else if (update_refs && unload_cls) {
2952 return "Concurrent marking (update refs) (unload classes)";
2953 } else if (proc_refs && unload_cls) {
2954 return "Concurrent marking (process weakrefs) (unload classes)";
2955 } else if (update_refs) {
2956 return "Concurrent marking (update refs)";
2957 } else if (proc_refs) {
2958 return "Concurrent marking (process weakrefs)";
2959 } else if (unload_cls) {
2960 return "Concurrent marking (unload classes)";
2961 } else {
2962 return "Concurrent marking";
2963 }
2964 }
2965
2966 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
2967 switch (point) {
2968 case _degenerated_unset:
2969 return "Pause Degenerated GC (<UNSET>)";
2970 case _degenerated_traversal:
2971 return "Pause Degenerated GC (Traversal)";
2972 case _degenerated_outside_cycle:
2973 return "Pause Degenerated GC (Outside of Cycle)";
2974 case _degenerated_mark:
2975 return "Pause Degenerated GC (Mark)";
2976 case _degenerated_evac:
2977 return "Pause Degenerated GC (Evacuation)";
2978 case _degenerated_updaterefs:
2979 return "Pause Degenerated GC (Update Refs)";
2980 default:
2981 ShouldNotReachHere();
2982 return "ERROR";
2983 }
2984 }
2985
2986 jushort* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2987 #ifdef ASSERT
2988 assert(_liveness_cache != NULL, "sanity");
2989 assert(worker_id < _max_workers, "sanity");
2990 for (uint i = 0; i < num_regions(); i++) {
2991 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2992 }
2993 #endif
2994 return _liveness_cache[worker_id];
2995 }
2996
2997 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2998 assert(worker_id < _max_workers, "sanity");
2999 assert(_liveness_cache != NULL, "sanity");
3000 jushort* ld = _liveness_cache[worker_id];
3001 for (uint i = 0; i < num_regions(); i++) {
3002 ShenandoahHeapRegion* r = get_region(i);
3003 jushort live = ld[i];
3004 if (live > 0) {
3005 r->increase_live_data_gc_words(live);
3006 ld[i] = 0;
3007 }
3008 }
3009 }