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/shenandoahBarrierSet.hpp"
36 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
37 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
38 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
39 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
40 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
41 #include "gc/shenandoah/shenandoahControlThread.hpp"
42 #include "gc/shenandoah/shenandoahFreeSet.hpp"
43 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
44 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
45 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
46 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
47 #include "gc/shenandoah/shenandoahMarkCompact.hpp"
48 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
49 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
50 #include "gc/shenandoah/shenandoahMetrics.hpp"
51 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
52 #include "gc/shenandoah/shenandoahNormalMode.hpp"
53 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
54 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
55 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
56 #include "gc/shenandoah/shenandoahPassiveMode.hpp"
57 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
58 #include "gc/shenandoah/shenandoahStringDedup.hpp"
59 #include "gc/shenandoah/shenandoahTaskqueue.hpp"
60 #include "gc/shenandoah/shenandoahTraversalMode.hpp"
61 #include "gc/shenandoah/shenandoahUtils.hpp"
62 #include "gc/shenandoah/shenandoahVerifier.hpp"
63 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
64 #include "gc/shenandoah/shenandoahVMOperations.hpp"
65 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
66 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
67 #if INCLUDE_JFR
68 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
69 #endif
70
71 #include "memory/metaspace.hpp"
72 #include "oops/compressedOops.inline.hpp"
73 #include "runtime/atomic.hpp"
74 #include "runtime/globals.hpp"
75 #include "runtime/interfaceSupport.inline.hpp"
76 #include "runtime/orderAccess.hpp"
77 #include "runtime/safepointMechanism.hpp"
78 #include "runtime/vmThread.hpp"
79 #include "services/mallocTracker.hpp"
80
81 #ifdef ASSERT
82 template <class T>
83 void ShenandoahAssertToSpaceClosure::do_oop_work(T* p) {
84 T o = RawAccess<>::oop_load(p);
85 if (! CompressedOops::is_null(o)) {
86 oop obj = CompressedOops::decode_not_null(o);
87 shenandoah_assert_not_forwarded(p, obj);
88 }
89 }
90
91 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_work(p); }
92 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_work(p); }
93 #endif
94
95 class ShenandoahPretouchHeapTask : public AbstractGangTask {
96 private:
97 ShenandoahRegionIterator _regions;
98 const size_t _page_size;
99 public:
100 ShenandoahPretouchHeapTask(size_t page_size) :
101 AbstractGangTask("Shenandoah Pretouch Heap"),
102 _page_size(page_size) {}
103
104 virtual void work(uint worker_id) {
105 ShenandoahHeapRegion* r = _regions.next();
106 while (r != NULL) {
107 os::pretouch_memory(r->bottom(), r->end(), _page_size);
108 r = _regions.next();
109 }
110 }
111 };
112
113 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
114 private:
115 ShenandoahRegionIterator _regions;
116 char* _bitmap_base;
117 const size_t _bitmap_size;
118 const size_t _page_size;
119 public:
120 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
121 AbstractGangTask("Shenandoah Pretouch Bitmap"),
122 _bitmap_base(bitmap_base),
123 _bitmap_size(bitmap_size),
124 _page_size(page_size) {}
125
126 virtual void work(uint worker_id) {
127 ShenandoahHeapRegion* r = _regions.next();
128 while (r != NULL) {
129 size_t start = r->region_number() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
130 size_t end = (r->region_number() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
131 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
132
133 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
134
135 r = _regions.next();
136 }
137 }
138 };
139
140 jint ShenandoahHeap::initialize() {
141 initialize_heuristics();
142
143 //
144 // Figure out heap sizing
145 //
146
147 size_t init_byte_size = InitialHeapSize;
148 size_t min_byte_size = MinHeapSize;
149 size_t max_byte_size = MaxHeapSize;
150 size_t heap_alignment = HeapAlignment;
151
152 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
153
154 if (ShenandoahAlwaysPreTouch) {
155 // Enabled pre-touch means the entire heap is committed right away.
156 init_byte_size = max_byte_size;
157 }
158
159 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
160 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
161
162 _num_regions = ShenandoahHeapRegion::region_count();
163
164 size_t num_committed_regions = init_byte_size / reg_size_bytes;
165 num_committed_regions = MIN2(num_committed_regions, _num_regions);
166 assert(num_committed_regions <= _num_regions, "sanity");
167 _initial_size = num_committed_regions * reg_size_bytes;
168
169 size_t num_min_regions = min_byte_size / reg_size_bytes;
170 num_min_regions = MIN2(num_min_regions, _num_regions);
171 assert(num_min_regions <= _num_regions, "sanity");
172 _minimum_size = num_min_regions * reg_size_bytes;
173
174 _committed = _initial_size;
175
176 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
177 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
178
179 //
180 // Reserve and commit memory for heap
181 //
182
183 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
184 initialize_reserved_region(heap_rs);
185 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
186 _heap_region_special = heap_rs.special();
187
188 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
189 "Misaligned heap: " PTR_FORMAT, p2i(base()));
190
191 #if SHENANDOAH_OPTIMIZED_OBJTASK
192 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
193 // Fail if we ever attempt to address more than we can.
194 if ((uintptr_t)heap_rs.end() >= ObjArrayChunkedTask::max_addressable()) {
195 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
196 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
197 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
198 p2i(heap_rs.base()), p2i(heap_rs.end()), ObjArrayChunkedTask::max_addressable());
199 vm_exit_during_initialization("Fatal Error", buf);
200 }
201 #endif
202
203 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
204 if (!_heap_region_special) {
205 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
206 "Cannot commit heap memory");
207 }
208
209 //
210 // Reserve and commit memory for bitmap(s)
211 //
212
213 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
214 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
215
216 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
217
218 guarantee(bitmap_bytes_per_region != 0,
219 "Bitmap bytes per region should not be zero");
220 guarantee(is_power_of_2(bitmap_bytes_per_region),
221 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
222
223 if (bitmap_page_size > bitmap_bytes_per_region) {
224 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
225 _bitmap_bytes_per_slice = bitmap_page_size;
226 } else {
227 _bitmap_regions_per_slice = 1;
228 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
229 }
230
231 guarantee(_bitmap_regions_per_slice >= 1,
232 "Should have at least one region per slice: " SIZE_FORMAT,
233 _bitmap_regions_per_slice);
234
235 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
236 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
237 _bitmap_bytes_per_slice, bitmap_page_size);
238
239 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
240 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
241 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
242 _bitmap_region_special = bitmap.special();
243
244 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
245 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
246 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
247 if (!_bitmap_region_special) {
248 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
249 "Cannot commit bitmap memory");
250 }
251
252 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
253
254 if (ShenandoahVerify) {
255 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
256 if (!verify_bitmap.special()) {
257 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
258 "Cannot commit verification bitmap memory");
259 }
260 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
261 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
262 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
263 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
264 }
265
266 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
267 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
268 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
269 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
270 _aux_bitmap_region_special = aux_bitmap.special();
271 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
272
273 //
274 // Create regions and region sets
275 //
276
277 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
278 _free_set = new ShenandoahFreeSet(this, _num_regions);
279 _collection_set = new ShenandoahCollectionSet(this, sh_rs.base(), sh_rs.size());
280
281 {
282 ShenandoahHeapLocker locker(lock());
283
284 size_t size_words = ShenandoahHeapRegion::region_size_words();
285
286 for (size_t i = 0; i < _num_regions; i++) {
287 HeapWord* start = (HeapWord*)sh_rs.base() + size_words * i;
288 bool is_committed = i < num_committed_regions;
289 ShenandoahHeapRegion* r = new ShenandoahHeapRegion(this, start, size_words, i, is_committed);
290
291 _marking_context->initialize_top_at_mark_start(r);
292 _regions[i] = r;
293 assert(!collection_set()->is_in(i), "New region should not be in collection set");
294 }
295
296 // Initialize to complete
297 _marking_context->mark_complete();
298
299 _free_set->rebuild();
300 }
301
302 if (ShenandoahAlwaysPreTouch) {
303 assert(!AlwaysPreTouch, "Should have been overridden");
304
305 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
306 // before initialize() below zeroes it with initializing thread. For any given region,
307 // we touch the region and the corresponding bitmaps from the same thread.
308 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
309
310 size_t pretouch_heap_page_size = heap_page_size;
311 size_t pretouch_bitmap_page_size = bitmap_page_size;
312
313 #ifdef LINUX
314 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
315 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
316 // them into huge one. Therefore, we need to pretouch with smaller pages.
317 if (UseTransparentHugePages) {
318 pretouch_heap_page_size = (size_t)os::vm_page_size();
319 pretouch_bitmap_page_size = (size_t)os::vm_page_size();
320 }
321 #endif
322
323 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
324 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
325
326 log_info(gc, init)("Pretouch bitmap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
327 _num_regions, pretouch_bitmap_page_size);
328 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, pretouch_bitmap_page_size);
329 _workers->run_task(&bcl);
330
331 log_info(gc, init)("Pretouch heap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
332 _num_regions, pretouch_heap_page_size);
333 ShenandoahPretouchHeapTask hcl(pretouch_heap_page_size);
334 _workers->run_task(&hcl);
335 }
336
337 //
338 // Initialize the rest of GC subsystems
339 //
340
341 _liveness_cache = NEW_C_HEAP_ARRAY(jushort*, _max_workers, mtGC);
342 for (uint worker = 0; worker < _max_workers; worker++) {
343 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(jushort, _num_regions, mtGC);
344 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(jushort));
345 }
346
347 // There should probably be Shenandoah-specific options for these,
348 // just as there are G1-specific options.
349 {
350 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
351 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
352 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
353 }
354
355 _monitoring_support = new ShenandoahMonitoringSupport(this);
356 _phase_timings = new ShenandoahPhaseTimings();
357 ShenandoahStringDedup::initialize();
358 ShenandoahCodeRoots::initialize();
359
360 if (ShenandoahPacing) {
361 _pacer = new ShenandoahPacer(this);
362 _pacer->setup_for_idle();
363 } else {
364 _pacer = NULL;
365 }
366
367 _traversal_gc = strcmp(ShenandoahGCMode, "traversal") == 0 ?
368 new ShenandoahTraversalGC(this, _num_regions) :
369 NULL;
370
371 _control_thread = new ShenandoahControlThread();
372
373 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max",
374 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size),
375 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size),
376 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity())
377 );
378
379 log_info(gc, init)("Safepointing mechanism: %s",
380 SafepointMechanism::uses_thread_local_poll() ? "thread-local poll" :
381 (SafepointMechanism::uses_global_page_poll() ? "global-page poll" : "unknown"));
382
383 return JNI_OK;
384 }
385
386 void ShenandoahHeap::initialize_heuristics() {
387 if (ShenandoahGCMode != NULL) {
388 if (strcmp(ShenandoahGCMode, "traversal") == 0) {
389 _gc_mode = new ShenandoahTraversalMode();
390 } else if (strcmp(ShenandoahGCMode, "normal") == 0) {
391 _gc_mode = new ShenandoahNormalMode();
392 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
393 _gc_mode = new ShenandoahPassiveMode();
394 } else {
395 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
396 }
397 } else {
398 ShouldNotReachHere();
399 }
400 _gc_mode->initialize_flags();
401 _heuristics = _gc_mode->initialize_heuristics();
402
403 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
404 vm_exit_during_initialization(
405 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
406 _heuristics->name()));
407 }
408 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
409 vm_exit_during_initialization(
410 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
411 _heuristics->name()));
412 }
413 log_info(gc, init)("Shenandoah heuristics: %s",
414 _heuristics->name());
415 }
416
417 #ifdef _MSC_VER
418 #pragma warning( push )
419 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
420 #endif
421
422 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
423 CollectedHeap(),
424 _initial_size(0),
425 _used(0),
426 _committed(0),
427 _bytes_allocated_since_gc_start(0),
428 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
429 _workers(NULL),
430 _safepoint_workers(NULL),
431 _heap_region_special(false),
432 _num_regions(0),
433 _regions(NULL),
434 _update_refs_iterator(this),
435 _control_thread(NULL),
436 _shenandoah_policy(policy),
437 _heuristics(NULL),
438 _free_set(NULL),
439 _scm(new ShenandoahConcurrentMark()),
440 _traversal_gc(NULL),
441 _full_gc(new ShenandoahMarkCompact()),
442 _pacer(NULL),
443 _verifier(NULL),
444 _phase_timings(NULL),
445 _monitoring_support(NULL),
446 _memory_pool(NULL),
447 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
448 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
449 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
450 _soft_ref_policy(),
451 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
452 _ref_processor(NULL),
453 _marking_context(NULL),
454 _bitmap_size(0),
455 _bitmap_regions_per_slice(0),
456 _bitmap_bytes_per_slice(0),
457 _bitmap_region_special(false),
458 _aux_bitmap_region_special(false),
459 _liveness_cache(NULL),
460 _collection_set(NULL)
461 {
462 log_info(gc, init)("GC threads: " UINT32_FORMAT " parallel, " UINT32_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
463 log_info(gc, init)("Reference processing: %s", ParallelRefProcEnabled ? "parallel" : "serial");
464
465 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
466
467 _max_workers = MAX2(_max_workers, 1U);
468 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
469 /* are_GC_task_threads */ true,
470 /* are_ConcurrentGC_threads */ true);
471 if (_workers == NULL) {
472 vm_exit_during_initialization("Failed necessary allocation.");
473 } else {
474 _workers->initialize_workers();
475 }
476
477 if (ParallelGCThreads > 1) {
478 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
479 ParallelGCThreads,
480 /* are_GC_task_threads */ false,
481 /* are_ConcurrentGC_threads */ false);
482 _safepoint_workers->initialize_workers();
483 }
484 }
485
486 #ifdef _MSC_VER
487 #pragma warning( pop )
488 #endif
489
490 class ShenandoahResetBitmapTask : public AbstractGangTask {
491 private:
492 ShenandoahRegionIterator _regions;
493
494 public:
495 ShenandoahResetBitmapTask() :
496 AbstractGangTask("Parallel Reset Bitmap Task") {}
497
498 void work(uint worker_id) {
499 ShenandoahHeapRegion* region = _regions.next();
500 ShenandoahHeap* heap = ShenandoahHeap::heap();
501 ShenandoahMarkingContext* const ctx = heap->marking_context();
502 while (region != NULL) {
503 if (heap->is_bitmap_slice_committed(region)) {
504 ctx->clear_bitmap(region);
505 }
506 region = _regions.next();
507 }
508 }
509 };
510
511 void ShenandoahHeap::reset_mark_bitmap() {
512 assert_gc_workers(_workers->active_workers());
513 mark_incomplete_marking_context();
514
515 ShenandoahResetBitmapTask task;
516 _workers->run_task(&task);
517 }
518
519 void ShenandoahHeap::print_on(outputStream* st) const {
520 st->print_cr("Shenandoah Heap");
521 st->print_cr(" " SIZE_FORMAT "%s total, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
522 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
523 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
524 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
525 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
526 num_regions(),
527 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
528 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
529
530 st->print("Status: ");
531 if (has_forwarded_objects()) st->print("has forwarded objects, ");
532 if (is_concurrent_mark_in_progress()) st->print("marking, ");
533 if (is_evacuation_in_progress()) st->print("evacuating, ");
534 if (is_update_refs_in_progress()) st->print("updating refs, ");
535 if (is_concurrent_traversal_in_progress()) st->print("traversal, ");
536 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
537 if (is_full_gc_in_progress()) st->print("full gc, ");
538 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
539 if (is_concurrent_root_in_progress()) st->print("concurrent roots, ");
540
541 if (cancelled_gc()) {
542 st->print("cancelled");
543 } else {
544 st->print("not cancelled");
545 }
546 st->cr();
547
548 st->print_cr("Reserved region:");
549 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
550 p2i(reserved_region().start()),
551 p2i(reserved_region().end()));
552
553 ShenandoahCollectionSet* cset = collection_set();
554 st->print_cr("Collection set:");
555 if (cset != NULL) {
556 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
557 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
558 } else {
559 st->print_cr(" (NULL)");
560 }
561
562 st->cr();
563 MetaspaceUtils::print_on(st);
564
565 if (Verbose) {
566 print_heap_regions_on(st);
567 }
568 }
569
570 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
571 public:
572 void do_thread(Thread* thread) {
573 assert(thread != NULL, "Sanity");
574 assert(thread->is_Worker_thread(), "Only worker thread expected");
575 ShenandoahThreadLocalData::initialize_gclab(thread);
576 }
577 };
578
579 void ShenandoahHeap::post_initialize() {
580 CollectedHeap::post_initialize();
581 MutexLocker ml(Threads_lock);
582
583 ShenandoahInitWorkerGCLABClosure init_gclabs;
584 _workers->threads_do(&init_gclabs);
585
586 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
587 // Now, we will let WorkGang to initialize gclab when new worker is created.
588 _workers->set_initialize_gclab();
589
590 _scm->initialize(_max_workers);
591 _full_gc->initialize(_gc_timer);
592
593 ref_processing_init();
594
595 _heuristics->initialize();
596
597 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
598 }
599
600 size_t ShenandoahHeap::used() const {
601 return Atomic::load_acquire(&_used);
602 }
603
604 size_t ShenandoahHeap::committed() const {
605 OrderAccess::acquire();
606 return _committed;
607 }
608
609 void ShenandoahHeap::increase_committed(size_t bytes) {
610 assert_heaplock_or_safepoint();
611 _committed += bytes;
612 }
613
614 void ShenandoahHeap::decrease_committed(size_t bytes) {
615 assert_heaplock_or_safepoint();
616 _committed -= bytes;
617 }
618
619 void ShenandoahHeap::increase_used(size_t bytes) {
620 Atomic::add(&_used, bytes);
621 }
622
623 void ShenandoahHeap::set_used(size_t bytes) {
624 Atomic::release_store_fence(&_used, bytes);
625 }
626
627 void ShenandoahHeap::decrease_used(size_t bytes) {
628 assert(used() >= bytes, "never decrease heap size by more than we've left");
629 Atomic::sub(&_used, bytes);
630 }
631
632 void ShenandoahHeap::increase_allocated(size_t bytes) {
633 Atomic::add(&_bytes_allocated_since_gc_start, bytes);
634 }
635
636 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
637 size_t bytes = words * HeapWordSize;
638 if (!waste) {
639 increase_used(bytes);
640 }
641 increase_allocated(bytes);
642 if (ShenandoahPacing) {
643 control_thread()->pacing_notify_alloc(words);
644 if (waste) {
645 pacer()->claim_for_alloc(words, true);
646 }
647 }
648 }
649
650 size_t ShenandoahHeap::capacity() const {
651 return committed();
652 }
653
654 size_t ShenandoahHeap::max_capacity() const {
655 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
656 }
657
658 size_t ShenandoahHeap::min_capacity() const {
659 return _minimum_size;
660 }
661
662 size_t ShenandoahHeap::initial_capacity() const {
663 return _initial_size;
664 }
665
666 bool ShenandoahHeap::is_in(const void* p) const {
667 HeapWord* heap_base = (HeapWord*) base();
668 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
669 return p >= heap_base && p < last_region_end;
670 }
671
672 void ShenandoahHeap::op_uncommit(double shrink_before) {
673 assert (ShenandoahUncommit, "should be enabled");
674
675 // Application allocates from the beginning of the heap, and GC allocates at
676 // the end of it. It is more efficient to uncommit from the end, so that applications
677 // could enjoy the near committed regions. GC allocations are much less frequent,
678 // and therefore can accept the committing costs.
679
680 size_t count = 0;
681 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
682 ShenandoahHeapRegion* r = get_region(i - 1);
683 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
684 ShenandoahHeapLocker locker(lock());
685 if (r->is_empty_committed()) {
686 // Do not uncommit below minimal capacity
687 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
688 break;
689 }
690
691 r->make_uncommitted();
692 count++;
693 }
694 }
695 SpinPause(); // allow allocators to take the lock
696 }
697
698 if (count > 0) {
699 control_thread()->notify_heap_changed();
700 }
701 }
702
703 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
704 // New object should fit the GCLAB size
705 size_t min_size = MAX2(size, PLAB::min_size());
706
707 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
708 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
709 new_size = MIN2(new_size, PLAB::max_size());
710 new_size = MAX2(new_size, PLAB::min_size());
711
712 // Record new heuristic value even if we take any shortcut. This captures
713 // the case when moderately-sized objects always take a shortcut. At some point,
714 // heuristics should catch up with them.
715 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
716
717 if (new_size < size) {
718 // New size still does not fit the object. Fall back to shared allocation.
719 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
720 return NULL;
721 }
722
723 // Retire current GCLAB, and allocate a new one.
724 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
725 gclab->retire();
726
727 size_t actual_size = 0;
728 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
729 if (gclab_buf == NULL) {
730 return NULL;
731 }
732
733 assert (size <= actual_size, "allocation should fit");
734
735 if (ZeroTLAB) {
736 // ..and clear it.
737 Copy::zero_to_words(gclab_buf, actual_size);
738 } else {
739 // ...and zap just allocated object.
740 #ifdef ASSERT
741 // Skip mangling the space corresponding to the object header to
742 // ensure that the returned space is not considered parsable by
743 // any concurrent GC thread.
744 size_t hdr_size = oopDesc::header_size();
745 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
746 #endif // ASSERT
747 }
748 gclab->set_buf(gclab_buf, actual_size);
749 return gclab->allocate(size);
750 }
751
752 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
753 size_t requested_size,
754 size_t* actual_size) {
755 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
756 HeapWord* res = allocate_memory(req);
757 if (res != NULL) {
758 *actual_size = req.actual_size();
759 } else {
760 *actual_size = 0;
761 }
762 return res;
763 }
764
765 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
766 size_t word_size,
767 size_t* actual_size) {
768 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
769 HeapWord* res = allocate_memory(req);
770 if (res != NULL) {
771 *actual_size = req.actual_size();
772 } else {
773 *actual_size = 0;
774 }
775 return res;
776 }
777
778 ShenandoahHeap* ShenandoahHeap::heap() {
779 CollectedHeap* heap = Universe::heap();
780 assert(heap != NULL, "Unitialized access to ShenandoahHeap::heap()");
781 assert(heap->kind() == CollectedHeap::Shenandoah, "not a shenandoah heap");
782 return (ShenandoahHeap*) heap;
783 }
784
785 ShenandoahHeap* ShenandoahHeap::heap_no_check() {
786 CollectedHeap* heap = Universe::heap();
787 return (ShenandoahHeap*) heap;
788 }
789
790 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
791 intptr_t pacer_epoch = 0;
792 bool in_new_region = false;
793 HeapWord* result = NULL;
794
795 if (req.is_mutator_alloc()) {
796 if (ShenandoahPacing) {
797 pacer()->pace_for_alloc(req.size());
798 pacer_epoch = pacer()->epoch();
799 }
800
801 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
802 result = allocate_memory_under_lock(req, in_new_region);
803 }
804
805 // Allocation failed, block until control thread reacted, then retry allocation.
806 //
807 // It might happen that one of the threads requesting allocation would unblock
808 // way later after GC happened, only to fail the second allocation, because
809 // other threads have already depleted the free storage. In this case, a better
810 // strategy is to try again, as long as GC makes progress.
811 //
812 // Then, we need to make sure the allocation was retried after at least one
813 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
814
815 size_t tries = 0;
816
817 while (result == NULL && _progress_last_gc.is_set()) {
818 tries++;
819 control_thread()->handle_alloc_failure(req.size());
820 result = allocate_memory_under_lock(req, in_new_region);
821 }
822
823 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
824 tries++;
825 control_thread()->handle_alloc_failure(req.size());
826 result = allocate_memory_under_lock(req, in_new_region);
827 }
828
829 } else {
830 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
831 result = allocate_memory_under_lock(req, in_new_region);
832 // Do not call handle_alloc_failure() here, because we cannot block.
833 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
834 }
835
836 if (in_new_region) {
837 control_thread()->notify_heap_changed();
838 }
839
840 if (result != NULL) {
841 size_t requested = req.size();
842 size_t actual = req.actual_size();
843
844 assert (req.is_lab_alloc() || (requested == actual),
845 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
846 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
847
848 if (req.is_mutator_alloc()) {
849 notify_mutator_alloc_words(actual, false);
850
851 // If we requested more than we were granted, give the rest back to pacer.
852 // This only matters if we are in the same pacing epoch: do not try to unpace
853 // over the budget for the other phase.
854 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
855 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
856 }
857 } else {
858 increase_used(actual*HeapWordSize);
859 }
860 }
861
862 return result;
863 }
864
865 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
866 ShenandoahHeapLocker locker(lock());
867 return _free_set->allocate(req, in_new_region);
868 }
869
870 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
871 bool* gc_overhead_limit_was_exceeded) {
872 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
873 return allocate_memory(req);
874 }
875
876 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
877 size_t size,
878 Metaspace::MetadataType mdtype) {
879 MetaWord* result;
880
881 // Inform metaspace OOM to GC heuristics if class unloading is possible.
882 if (heuristics()->can_unload_classes()) {
883 ShenandoahHeuristics* h = heuristics();
884 h->record_metaspace_oom();
885 }
886
887 // Expand and retry allocation
888 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
889 if (result != NULL) {
890 return result;
891 }
892
893 // Start full GC
894 collect(GCCause::_metadata_GC_clear_soft_refs);
895
896 // Retry allocation
897 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
898 if (result != NULL) {
899 return result;
900 }
901
902 // Expand and retry allocation
903 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
904 if (result != NULL) {
905 return result;
906 }
907
908 // Out of memory
909 return NULL;
910 }
911
912 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
913 private:
914 ShenandoahHeap* const _heap;
915 Thread* const _thread;
916 public:
917 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
918 _heap(heap), _thread(Thread::current()) {}
919
920 void do_object(oop p) {
921 shenandoah_assert_marked(NULL, p);
922 if (!p->is_forwarded()) {
923 _heap->evacuate_object(p, _thread);
924 }
925 }
926 };
927
928 class ShenandoahEvacuationTask : public AbstractGangTask {
929 private:
930 ShenandoahHeap* const _sh;
931 ShenandoahCollectionSet* const _cs;
932 bool _concurrent;
933 public:
934 ShenandoahEvacuationTask(ShenandoahHeap* sh,
935 ShenandoahCollectionSet* cs,
936 bool concurrent) :
937 AbstractGangTask("Parallel Evacuation Task"),
938 _sh(sh),
939 _cs(cs),
940 _concurrent(concurrent)
941 {}
942
943 void work(uint worker_id) {
944 if (_concurrent) {
945 ShenandoahConcurrentWorkerSession worker_session(worker_id);
946 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
947 ShenandoahEvacOOMScope oom_evac_scope;
948 do_work();
949 } else {
950 ShenandoahParallelWorkerSession worker_session(worker_id);
951 ShenandoahEvacOOMScope oom_evac_scope;
952 do_work();
953 }
954 }
955
956 private:
957 void do_work() {
958 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
959 ShenandoahHeapRegion* r;
960 while ((r =_cs->claim_next()) != NULL) {
961 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->region_number());
962 _sh->marked_object_iterate(r, &cl);
963
964 if (ShenandoahPacing) {
965 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
966 }
967
968 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
969 break;
970 }
971 }
972 }
973 };
974
975 void ShenandoahHeap::trash_cset_regions() {
976 ShenandoahHeapLocker locker(lock());
977
978 ShenandoahCollectionSet* set = collection_set();
979 ShenandoahHeapRegion* r;
980 set->clear_current_index();
981 while ((r = set->next()) != NULL) {
982 r->make_trash();
983 }
984 collection_set()->clear();
985 }
986
987 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
988 st->print_cr("Heap Regions:");
989 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
990 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
991 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start (previous, next)");
992 st->print_cr("SN=alloc sequence numbers (first mutator, last mutator, first gc, last gc)");
993
994 for (size_t i = 0; i < num_regions(); i++) {
995 get_region(i)->print_on(st);
996 }
997 }
998
999 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1000 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1001
1002 oop humongous_obj = oop(start->bottom());
1003 size_t size = humongous_obj->size();
1004 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1005 size_t index = start->region_number() + required_regions - 1;
1006
1007 assert(!start->has_live(), "liveness must be zero");
1008
1009 for(size_t i = 0; i < required_regions; i++) {
1010 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1011 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1012 ShenandoahHeapRegion* region = get_region(index --);
1013
1014 assert(region->is_humongous(), "expect correct humongous start or continuation");
1015 assert(!region->is_cset(), "Humongous region should not be in collection set");
1016
1017 region->make_trash_immediate();
1018 }
1019 }
1020
1021 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1022 public:
1023 void do_thread(Thread* thread) {
1024 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1025 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1026 gclab->retire();
1027 }
1028 };
1029
1030 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
1031 if (UseTLAB) {
1032 CollectedHeap::ensure_parsability(retire_tlabs);
1033 }
1034 ShenandoahRetireGCLABClosure cl;
1035 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1036 cl.do_thread(t);
1037 }
1038 workers()->threads_do(&cl);
1039 }
1040
1041 void ShenandoahHeap::resize_tlabs() {
1042 CollectedHeap::resize_all_tlabs();
1043 }
1044
1045 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1046 private:
1047 ShenandoahRootEvacuator* _rp;
1048
1049 public:
1050 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1051 AbstractGangTask("Shenandoah evacuate and update roots"),
1052 _rp(rp) {}
1053
1054 void work(uint worker_id) {
1055 ShenandoahParallelWorkerSession worker_session(worker_id);
1056 ShenandoahEvacOOMScope oom_evac_scope;
1057 ShenandoahEvacuateUpdateRootsClosure cl;
1058 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1059 _rp->roots_do(worker_id, &cl);
1060 }
1061 };
1062
1063 void ShenandoahHeap::evacuate_and_update_roots() {
1064 #if COMPILER2_OR_JVMCI
1065 DerivedPointerTable::clear();
1066 #endif
1067 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1068 {
1069 // Include concurrent roots if current cycle can not process those roots concurrently
1070 ShenandoahRootEvacuator rp(workers()->active_workers(),
1071 ShenandoahPhaseTimings::init_evac,
1072 !ShenandoahConcurrentRoots::should_do_concurrent_roots(),
1073 !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
1074 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1075 workers()->run_task(&roots_task);
1076 }
1077
1078 #if COMPILER2_OR_JVMCI
1079 DerivedPointerTable::update_pointers();
1080 #endif
1081 }
1082
1083 // Returns size in bytes
1084 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1085 if (ShenandoahElasticTLAB) {
1086 // With Elastic TLABs, return the max allowed size, and let the allocation path
1087 // figure out the safe size for current allocation.
1088 return ShenandoahHeapRegion::max_tlab_size_bytes();
1089 } else {
1090 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1091 }
1092 }
1093
1094 size_t ShenandoahHeap::max_tlab_size() const {
1095 // Returns size in words
1096 return ShenandoahHeapRegion::max_tlab_size_words();
1097 }
1098
1099 class ShenandoahRetireAndResetGCLABClosure : public ThreadClosure {
1100 public:
1101 void do_thread(Thread* thread) {
1102 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1103 gclab->retire();
1104 if (ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1105 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1106 }
1107 }
1108 };
1109
1110 void ShenandoahHeap::retire_and_reset_gclabs() {
1111 ShenandoahRetireAndResetGCLABClosure cl;
1112 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1113 cl.do_thread(t);
1114 }
1115 workers()->threads_do(&cl);
1116 }
1117
1118 void ShenandoahHeap::collect(GCCause::Cause cause) {
1119 control_thread()->request_gc(cause);
1120 }
1121
1122 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1123 //assert(false, "Shouldn't need to do full collections");
1124 }
1125
1126 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1127 Space* sp = heap_region_containing(addr);
1128 if (sp != NULL) {
1129 return sp->block_start(addr);
1130 }
1131 return NULL;
1132 }
1133
1134 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1135 Space* sp = heap_region_containing(addr);
1136 return sp->block_is_obj(addr);
1137 }
1138
1139 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1140 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1141 }
1142
1143 jlong ShenandoahHeap::millis_since_last_gc() {
1144 double v = heuristics()->time_since_last_gc() * 1000;
1145 assert(0 <= v && v <= max_jlong, "value should fit: %f", v);
1146 return (jlong)v;
1147 }
1148
1149 void ShenandoahHeap::prepare_for_verify() {
1150 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1151 make_parsable(false);
1152 }
1153 }
1154
1155 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1156 workers()->print_worker_threads_on(st);
1157 if (ShenandoahStringDedup::is_enabled()) {
1158 ShenandoahStringDedup::print_worker_threads_on(st);
1159 }
1160 }
1161
1162 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1163 workers()->threads_do(tcl);
1164 if (_safepoint_workers != NULL) {
1165 _safepoint_workers->threads_do(tcl);
1166 }
1167 if (ShenandoahStringDedup::is_enabled()) {
1168 ShenandoahStringDedup::threads_do(tcl);
1169 }
1170 }
1171
1172 void ShenandoahHeap::print_tracing_info() const {
1173 LogTarget(Info, gc, stats) lt;
1174 if (lt.is_enabled()) {
1175 ResourceMark rm;
1176 LogStream ls(lt);
1177
1178 phase_timings()->print_on(&ls);
1179
1180 ls.cr();
1181 ls.cr();
1182
1183 shenandoah_policy()->print_gc_stats(&ls);
1184
1185 ls.cr();
1186 ls.cr();
1187
1188 if (ShenandoahPacing) {
1189 pacer()->print_on(&ls);
1190 }
1191
1192 ls.cr();
1193 ls.cr();
1194 }
1195 }
1196
1197 void ShenandoahHeap::verify(VerifyOption vo) {
1198 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1199 if (ShenandoahVerify) {
1200 verifier()->verify_generic(vo);
1201 } else {
1202 // TODO: Consider allocating verification bitmaps on demand,
1203 // and turn this on unconditionally.
1204 }
1205 }
1206 }
1207 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1208 return _free_set->capacity();
1209 }
1210
1211 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1212 private:
1213 MarkBitMap* _bitmap;
1214 Stack<oop,mtGC>* _oop_stack;
1215 ShenandoahHeap* const _heap;
1216 ShenandoahMarkingContext* const _marking_context;
1217
1218 template <class T>
1219 void do_oop_work(T* p) {
1220 T o = RawAccess<>::oop_load(p);
1221 if (!CompressedOops::is_null(o)) {
1222 oop obj = CompressedOops::decode_not_null(o);
1223 if (_heap->is_concurrent_root_in_progress() && !_marking_context->is_marked(obj)) {
1224 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1225 return;
1226 }
1227 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1228
1229 assert(oopDesc::is_oop(obj), "must be a valid oop");
1230 if (!_bitmap->is_marked((HeapWord*) obj)) {
1231 _bitmap->mark((HeapWord*) obj);
1232 _oop_stack->push(obj);
1233 }
1234 }
1235 }
1236 public:
1237 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1238 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1239 _marking_context(_heap->marking_context()) {}
1240 void do_oop(oop* p) { do_oop_work(p); }
1241 void do_oop(narrowOop* p) { do_oop_work(p); }
1242 };
1243
1244 /*
1245 * This is public API, used in preparation of object_iterate().
1246 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1247 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1248 * control, we call SH::make_tlabs_parsable().
1249 */
1250 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1251 // No-op.
1252 }
1253
1254 /*
1255 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1256 *
1257 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1258 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1259 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1260 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1261 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1262 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1263 * wiped the bitmap in preparation for next marking).
1264 *
1265 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1266 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1267 * is allowed to report dead objects, but is not required to do so.
1268 */
1269 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1270 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1271 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1272 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1273 return;
1274 }
1275
1276 // Reset bitmap
1277 _aux_bit_map.clear();
1278
1279 Stack<oop,mtGC> oop_stack;
1280
1281 // First, we process GC roots according to current GC cycle. This populates the work stack with initial objects.
1282 ShenandoahHeapIterationRootScanner rp;
1283 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1284
1285 rp.roots_do(&oops);
1286
1287 // Work through the oop stack to traverse heap.
1288 while (! oop_stack.is_empty()) {
1289 oop obj = oop_stack.pop();
1290 assert(oopDesc::is_oop(obj), "must be a valid oop");
1291 cl->do_object(obj);
1292 obj->oop_iterate(&oops);
1293 }
1294
1295 assert(oop_stack.is_empty(), "should be empty");
1296
1297 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1298 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1299 }
1300 }
1301
1302 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1303 void ShenandoahHeap::keep_alive(oop obj) {
1304 if (is_concurrent_mark_in_progress()) {
1305 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1306 }
1307 }
1308
1309 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1310 for (size_t i = 0; i < num_regions(); i++) {
1311 ShenandoahHeapRegion* current = get_region(i);
1312 blk->heap_region_do(current);
1313 }
1314 }
1315
1316 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1317 private:
1318 ShenandoahHeap* const _heap;
1319 ShenandoahHeapRegionClosure* const _blk;
1320
1321 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));
1322 volatile size_t _index;
1323 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
1324
1325 public:
1326 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1327 AbstractGangTask("Parallel Region Task"),
1328 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1329
1330 void work(uint worker_id) {
1331 size_t stride = ShenandoahParallelRegionStride;
1332
1333 size_t max = _heap->num_regions();
1334 while (_index < max) {
1335 size_t cur = Atomic::add(&_index, stride) - stride;
1336 size_t start = cur;
1337 size_t end = MIN2(cur + stride, max);
1338 if (start >= max) break;
1339
1340 for (size_t i = cur; i < end; i++) {
1341 ShenandoahHeapRegion* current = _heap->get_region(i);
1342 _blk->heap_region_do(current);
1343 }
1344 }
1345 }
1346 };
1347
1348 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1349 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1350 if (num_regions() > ShenandoahParallelRegionStride) {
1351 ShenandoahParallelHeapRegionTask task(blk);
1352 workers()->run_task(&task);
1353 } else {
1354 heap_region_iterate(blk);
1355 }
1356 }
1357
1358 class ShenandoahClearLivenessClosure : public ShenandoahHeapRegionClosure {
1359 private:
1360 ShenandoahMarkingContext* const _ctx;
1361 public:
1362 ShenandoahClearLivenessClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1363
1364 void heap_region_do(ShenandoahHeapRegion* r) {
1365 if (r->is_active()) {
1366 r->clear_live_data();
1367 _ctx->capture_top_at_mark_start(r);
1368 } else {
1369 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1370 assert(_ctx->top_at_mark_start(r) == r->top(),
1371 "Region " SIZE_FORMAT " should already have correct TAMS", r->region_number());
1372 }
1373 }
1374
1375 bool is_thread_safe() { return true; }
1376 };
1377
1378 void ShenandoahHeap::op_init_mark() {
1379 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1380 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1381
1382 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1383 assert(!marking_context()->is_complete(), "should not be complete");
1384 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1385
1386 if (ShenandoahVerify) {
1387 verifier()->verify_before_concmark();
1388 }
1389
1390 if (VerifyBeforeGC) {
1391 Universe::verify();
1392 }
1393
1394 set_concurrent_mark_in_progress(true);
1395 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1396 {
1397 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1398 make_parsable(true);
1399 }
1400
1401 {
1402 ShenandoahGCPhase phase(ShenandoahPhaseTimings::clear_liveness);
1403 ShenandoahClearLivenessClosure clc;
1404 parallel_heap_region_iterate(&clc);
1405 }
1406
1407 // Make above changes visible to worker threads
1408 OrderAccess::fence();
1409
1410 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1411
1412 if (UseTLAB) {
1413 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1414 resize_tlabs();
1415 }
1416
1417 if (ShenandoahPacing) {
1418 pacer()->setup_for_mark();
1419 }
1420
1421 // Arm nmethods for concurrent marking. When a nmethod is about to be executed,
1422 // we need to make sure that all its metadata are marked. alternative is to remark
1423 // thread roots at final mark pause, but it can be potential latency killer.
1424 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1425 ShenandoahCodeRoots::arm_nmethods();
1426 }
1427 }
1428
1429 void ShenandoahHeap::op_mark() {
1430 concurrent_mark()->mark_from_roots();
1431 }
1432
1433 class ShenandoahCompleteLivenessClosure : public ShenandoahHeapRegionClosure {
1434 private:
1435 ShenandoahMarkingContext* const _ctx;
1436 public:
1437 ShenandoahCompleteLivenessClosure() : _ctx(ShenandoahHeap::heap()->complete_marking_context()) {}
1438
1439 void heap_region_do(ShenandoahHeapRegion* r) {
1440 if (r->is_active()) {
1441 HeapWord *tams = _ctx->top_at_mark_start(r);
1442 HeapWord *top = r->top();
1443 if (top > tams) {
1444 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1445 }
1446 } else {
1447 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1448 assert(_ctx->top_at_mark_start(r) == r->top(),
1449 "Region " SIZE_FORMAT " should have correct TAMS", r->region_number());
1450 }
1451 }
1452
1453 bool is_thread_safe() { return true; }
1454 };
1455
1456 void ShenandoahHeap::op_final_mark() {
1457 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1458 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1459
1460 // It is critical that we
1461 // evacuate roots right after finishing marking, so that we don't
1462 // get unmarked objects in the roots.
1463
1464 if (!cancelled_gc()) {
1465 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1466
1467 // Marking is completed, deactivate SATB barrier
1468 set_concurrent_mark_in_progress(false);
1469 mark_complete_marking_context();
1470
1471 parallel_cleaning(false /* full gc*/);
1472
1473 if (ShenandoahVerify) {
1474 verifier()->verify_roots_no_forwarded();
1475 }
1476 // All allocations past TAMS are implicitly live, adjust the region data.
1477 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1478 {
1479 ShenandoahGCPhase phase(ShenandoahPhaseTimings::complete_liveness);
1480 ShenandoahCompleteLivenessClosure cl;
1481 parallel_heap_region_iterate(&cl);
1482 }
1483
1484 // Force the threads to reacquire their TLABs outside the collection set.
1485 {
1486 ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs);
1487 make_parsable(true);
1488 }
1489
1490 // We are about to select the collection set, make sure it knows about
1491 // current pinning status. Also, this allows trashing more regions that
1492 // now have their pinning status dropped.
1493 {
1494 ShenandoahGCPhase phase(ShenandoahPhaseTimings::sync_pinned);
1495 sync_pinned_region_status();
1496 }
1497
1498 // Trash the collection set left over from previous cycle, if any.
1499 {
1500 ShenandoahGCPhase phase(ShenandoahPhaseTimings::trash_cset);
1501 trash_cset_regions();
1502 }
1503
1504 {
1505 ShenandoahGCPhase phase(ShenandoahPhaseTimings::prepare_evac);
1506
1507 ShenandoahHeapLocker locker(lock());
1508 _collection_set->clear();
1509 _free_set->clear();
1510
1511 heuristics()->choose_collection_set(_collection_set);
1512
1513 _free_set->rebuild();
1514 }
1515
1516 if (!is_degenerated_gc_in_progress()) {
1517 prepare_concurrent_roots();
1518 prepare_concurrent_unloading();
1519 }
1520
1521 // If collection set has candidates, start evacuation.
1522 // Otherwise, bypass the rest of the cycle.
1523 if (!collection_set()->is_empty()) {
1524 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1525
1526 if (ShenandoahVerify) {
1527 verifier()->verify_before_evacuation();
1528 }
1529
1530 // Remember limit for updating refs. It's guaranteed that we get no from-space-refs written
1531 // from here on.
1532 for (uint i = 0; i < num_regions(); i++) {
1533 ShenandoahHeapRegion* r = get_region(i);
1534 r->set_update_watermark(r->top());
1535 }
1536
1537 set_evacuation_in_progress(true);
1538 // From here on, we need to update references.
1539 set_has_forwarded_objects(true);
1540
1541 if (!is_degenerated_gc_in_progress()) {
1542 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1543 ShenandoahCodeRoots::arm_nmethods();
1544 }
1545 evacuate_and_update_roots();
1546 }
1547
1548 if (ShenandoahPacing) {
1549 pacer()->setup_for_evac();
1550 }
1551
1552 if (ShenandoahVerify) {
1553 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::None;
1554 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1555 types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots);
1556 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots);
1557 }
1558
1559 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1560 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CodeRoots);
1561 }
1562 verifier()->verify_roots_no_forwarded_except(types);
1563 verifier()->verify_during_evacuation();
1564 }
1565 } else {
1566 if (ShenandoahVerify) {
1567 verifier()->verify_after_concmark();
1568 }
1569
1570 if (VerifyAfterGC) {
1571 Universe::verify();
1572 }
1573 }
1574
1575 } else {
1576 // If this cycle was updating references, we need to keep the has_forwarded_objects
1577 // flag on, for subsequent phases to deal with it.
1578 concurrent_mark()->cancel();
1579 set_concurrent_mark_in_progress(false);
1580
1581 if (process_references()) {
1582 // Abandon reference processing right away: pre-cleaning must have failed.
1583 ReferenceProcessor *rp = ref_processor();
1584 rp->disable_discovery();
1585 rp->abandon_partial_discovery();
1586 rp->verify_no_references_recorded();
1587 }
1588 }
1589 }
1590
1591 void ShenandoahHeap::op_conc_evac() {
1592 ShenandoahEvacuationTask task(this, _collection_set, true);
1593 workers()->run_task(&task);
1594 }
1595
1596 void ShenandoahHeap::op_stw_evac() {
1597 ShenandoahEvacuationTask task(this, _collection_set, false);
1598 workers()->run_task(&task);
1599 }
1600
1601 void ShenandoahHeap::op_updaterefs() {
1602 update_heap_references(true);
1603 }
1604
1605 void ShenandoahHeap::op_cleanup() {
1606 free_set()->recycle_trash();
1607 }
1608
1609 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask {
1610 private:
1611 ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
1612 ShenandoahWeakRoots<true /*concurrent*/> _weak_roots;
1613 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots;
1614
1615 public:
1616 ShenandoahConcurrentRootsEvacUpdateTask() :
1617 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Roots Task") {
1618 }
1619
1620 void work(uint worker_id) {
1621 ShenandoahEvacOOMScope oom;
1622 {
1623 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
1624 // may race against OopStorage::release() calls.
1625 ShenandoahEvacUpdateOopStorageRootsClosure cl;
1626 _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1627 _weak_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1628 }
1629
1630 {
1631 ShenandoahEvacuateUpdateRootsClosure cl;
1632 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1633 _cld_roots.cld_do(&clds);
1634 }
1635 }
1636 };
1637
1638 void ShenandoahHeap::op_roots() {
1639 if (is_concurrent_root_in_progress()) {
1640 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1641 _unloader.unload();
1642 }
1643
1644 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1645 ShenandoahConcurrentRootsEvacUpdateTask task;
1646 workers()->run_task(&task);
1647 }
1648 }
1649
1650 set_concurrent_root_in_progress(false);
1651 }
1652
1653 void ShenandoahHeap::op_reset() {
1654 if (ShenandoahPacing) {
1655 pacer()->setup_for_reset();
1656 }
1657 reset_mark_bitmap();
1658 }
1659
1660 void ShenandoahHeap::op_preclean() {
1661 if (ShenandoahPacing) {
1662 pacer()->setup_for_preclean();
1663 }
1664 concurrent_mark()->preclean_weak_refs();
1665 }
1666
1667 void ShenandoahHeap::op_init_traversal() {
1668 traversal_gc()->init_traversal_collection();
1669 }
1670
1671 void ShenandoahHeap::op_traversal() {
1672 traversal_gc()->concurrent_traversal_collection();
1673 }
1674
1675 void ShenandoahHeap::op_final_traversal() {
1676 traversal_gc()->final_traversal_collection();
1677 }
1678
1679 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1680 ShenandoahMetricsSnapshot metrics;
1681 metrics.snap_before();
1682
1683 full_gc()->do_it(cause);
1684 if (UseTLAB) {
1685 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs);
1686 resize_all_tlabs();
1687 }
1688
1689 metrics.snap_after();
1690
1691 if (metrics.is_good_progress()) {
1692 _progress_last_gc.set();
1693 } else {
1694 // Nothing to do. Tell the allocation path that we have failed to make
1695 // progress, and it can finally fail.
1696 _progress_last_gc.unset();
1697 }
1698 }
1699
1700 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1701 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1702 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1703 // some phase, we have to upgrade the Degenerate GC to Full GC.
1704
1705 clear_cancelled_gc();
1706
1707 ShenandoahMetricsSnapshot metrics;
1708 metrics.snap_before();
1709
1710 switch (point) {
1711 case _degenerated_traversal:
1712 {
1713 // Drop the collection set. Note: this leaves some already forwarded objects
1714 // behind, which may be problematic, see comments for ShenandoahEvacAssist
1715 // workarounds in ShenandoahTraversalHeuristics.
1716
1717 ShenandoahHeapLocker locker(lock());
1718 collection_set()->clear_current_index();
1719 for (size_t i = 0; i < collection_set()->count(); i++) {
1720 ShenandoahHeapRegion* r = collection_set()->next();
1721 r->make_regular_bypass();
1722 }
1723 collection_set()->clear();
1724 }
1725 op_final_traversal();
1726 op_cleanup();
1727 return;
1728
1729 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1730 // but enters it at different points, depending on which concurrent phase had
1731 // degenerated.
1732
1733 case _degenerated_outside_cycle:
1734 // We have degenerated from outside the cycle, which means something is bad with
1735 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1736 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1737 // we can do the most aggressive degen cycle, which includes processing references and
1738 // class unloading, unless those features are explicitly disabled.
1739 //
1740 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1741 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1742 set_process_references(heuristics()->can_process_references());
1743 set_unload_classes(heuristics()->can_unload_classes());
1744
1745 if (is_traversal_mode()) {
1746 // Not possible to degenerate from here, upgrade to Full GC right away.
1747 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1748 op_degenerated_fail();
1749 return;
1750 }
1751
1752 op_reset();
1753
1754 op_init_mark();
1755 if (cancelled_gc()) {
1756 op_degenerated_fail();
1757 return;
1758 }
1759
1760 case _degenerated_mark:
1761 op_final_mark();
1762 if (cancelled_gc()) {
1763 op_degenerated_fail();
1764 return;
1765 }
1766
1767 if (!has_forwarded_objects() && ShenandoahConcurrentRoots::can_do_concurrent_class_unloading()) {
1768 // Disarm nmethods that armed for concurrent mark. On normal cycle, it would
1769 // be disarmed while conc-roots phase is running.
1770 // TODO: Call op_conc_roots() here instead
1771 ShenandoahCodeRoots::disarm_nmethods();
1772 }
1773
1774 op_cleanup();
1775
1776 case _degenerated_evac:
1777 // If heuristics thinks we should do the cycle, this flag would be set,
1778 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
1779 if (is_evacuation_in_progress()) {
1780
1781 // Degeneration under oom-evac protocol might have left some objects in
1782 // collection set un-evacuated. Restart evacuation from the beginning to
1783 // capture all objects. For all the objects that are already evacuated,
1784 // it would be a simple check, which is supposed to be fast. This is also
1785 // safe to do even without degeneration, as CSet iterator is at beginning
1786 // in preparation for evacuation anyway.
1787 //
1788 // Before doing that, we need to make sure we never had any cset-pinned
1789 // regions. This may happen if allocation failure happened when evacuating
1790 // the about-to-be-pinned object, oom-evac protocol left the object in
1791 // the collection set, and then the pin reached the cset region. If we continue
1792 // the cycle here, we would trash the cset and alive objects in it. To avoid
1793 // it, we fail degeneration right away and slide into Full GC to recover.
1794
1795 {
1796 sync_pinned_region_status();
1797 collection_set()->clear_current_index();
1798
1799 ShenandoahHeapRegion* r;
1800 while ((r = collection_set()->next()) != NULL) {
1801 if (r->is_pinned()) {
1802 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1803 op_degenerated_fail();
1804 return;
1805 }
1806 }
1807
1808 collection_set()->clear_current_index();
1809 }
1810
1811 op_stw_evac();
1812 if (cancelled_gc()) {
1813 op_degenerated_fail();
1814 return;
1815 }
1816 }
1817
1818 // If heuristics thinks we should do the cycle, this flag would be set,
1819 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
1820 if (has_forwarded_objects()) {
1821 op_init_updaterefs();
1822 if (cancelled_gc()) {
1823 op_degenerated_fail();
1824 return;
1825 }
1826 }
1827
1828 case _degenerated_updaterefs:
1829 if (has_forwarded_objects()) {
1830 op_final_updaterefs();
1831 if (cancelled_gc()) {
1832 op_degenerated_fail();
1833 return;
1834 }
1835 }
1836
1837 op_cleanup();
1838 break;
1839
1840 default:
1841 ShouldNotReachHere();
1842 }
1843
1844 if (ShenandoahVerify) {
1845 verifier()->verify_after_degenerated();
1846 }
1847
1848 if (VerifyAfterGC) {
1849 Universe::verify();
1850 }
1851
1852 metrics.snap_after();
1853
1854 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
1855 // because that probably means the heap is overloaded and/or fragmented.
1856 if (!metrics.is_good_progress()) {
1857 _progress_last_gc.unset();
1858 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1859 op_degenerated_futile();
1860 } else {
1861 _progress_last_gc.set();
1862 }
1863 }
1864
1865 void ShenandoahHeap::op_degenerated_fail() {
1866 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
1867 shenandoah_policy()->record_degenerated_upgrade_to_full();
1868 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1869 }
1870
1871 void ShenandoahHeap::op_degenerated_futile() {
1872 shenandoah_policy()->record_degenerated_upgrade_to_full();
1873 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1874 }
1875
1876 void ShenandoahHeap::force_satb_flush_all_threads() {
1877 if (!is_concurrent_mark_in_progress() && !is_concurrent_traversal_in_progress()) {
1878 // No need to flush SATBs
1879 return;
1880 }
1881
1882 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1883 ShenandoahThreadLocalData::set_force_satb_flush(t, true);
1884 }
1885 // The threads are not "acquiring" their thread-local data, but it does not
1886 // hurt to "release" the updates here anyway.
1887 OrderAccess::fence();
1888 }
1889
1890 void ShenandoahHeap::set_gc_state_all_threads(char state) {
1891 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1892 ShenandoahThreadLocalData::set_gc_state(t, state);
1893 }
1894 }
1895
1896 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1897 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1898 _gc_state.set_cond(mask, value);
1899 set_gc_state_all_threads(_gc_state.raw_value());
1900 }
1901
1902 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1903 if (has_forwarded_objects()) {
1904 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
1905 } else {
1906 set_gc_state_mask(MARKING, in_progress);
1907 }
1908 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1909 }
1910
1911 void ShenandoahHeap::set_concurrent_traversal_in_progress(bool in_progress) {
1912 set_gc_state_mask(TRAVERSAL, in_progress);
1913 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1914 }
1915
1916 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1917 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1918 set_gc_state_mask(EVACUATION, in_progress);
1919 }
1920
1921 void ShenandoahHeap::set_concurrent_root_in_progress(bool in_progress) {
1922 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
1923 if (in_progress) {
1924 _concurrent_root_in_progress.set();
1925 } else {
1926 _concurrent_root_in_progress.unset();
1927 }
1928 }
1929
1930 void ShenandoahHeap::ref_processing_init() {
1931 assert(_max_workers > 0, "Sanity");
1932
1933 _ref_processor =
1934 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
1935 ParallelRefProcEnabled, // MT processing
1936 _max_workers, // Degree of MT processing
1937 true, // MT discovery
1938 _max_workers, // Degree of MT discovery
1939 false, // Reference discovery is not atomic
1940 NULL, // No closure, should be installed before use
1941 true); // Scale worker threads
1942
1943 shenandoah_assert_rp_isalive_not_installed();
1944 }
1945
1946 GCTracer* ShenandoahHeap::tracer() {
1947 return shenandoah_policy()->tracer();
1948 }
1949
1950 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1951 return _free_set->used();
1952 }
1953
1954 bool ShenandoahHeap::try_cancel_gc() {
1955 while (true) {
1956 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1957 if (prev == CANCELLABLE) return true;
1958 else if (prev == CANCELLED) return false;
1959 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
1960 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
1961 if (Thread::current()->is_Java_thread()) {
1962 // We need to provide a safepoint here, otherwise we might
1963 // spin forever if a SP is pending.
1964 ThreadBlockInVM sp(JavaThread::current());
1965 SpinPause();
1966 }
1967 }
1968 }
1969
1970 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1971 if (try_cancel_gc()) {
1972 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1973 log_info(gc)("%s", msg.buffer());
1974 Events::log(Thread::current(), "%s", msg.buffer());
1975 }
1976 }
1977
1978 uint ShenandoahHeap::max_workers() {
1979 return _max_workers;
1980 }
1981
1982 void ShenandoahHeap::stop() {
1983 // The shutdown sequence should be able to terminate when GC is running.
1984
1985 // Step 0. Notify policy to disable event recording.
1986 _shenandoah_policy->record_shutdown();
1987
1988 // Step 1. Notify control thread that we are in shutdown.
1989 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1990 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1991 control_thread()->prepare_for_graceful_shutdown();
1992
1993 // Step 2. Notify GC workers that we are cancelling GC.
1994 cancel_gc(GCCause::_shenandoah_stop_vm);
1995
1996 // Step 3. Wait until GC worker exits normally.
1997 control_thread()->stop();
1998
1999 // Step 4. Stop String Dedup thread if it is active
2000 if (ShenandoahStringDedup::is_enabled()) {
2001 ShenandoahStringDedup::stop();
2002 }
2003 }
2004
2005 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
2006 if (!unload_classes()) return;
2007 bool purged_class;
2008
2009 // Unload classes and purge SystemDictionary.
2010 {
2011 ShenandoahGCPhase phase(full_gc ?
2012 ShenandoahPhaseTimings::full_gc_purge_class_unload :
2013 ShenandoahPhaseTimings::purge_class_unload);
2014 purged_class = SystemDictionary::do_unloading(gc_timer());
2015 }
2016
2017 {
2018 ShenandoahGCPhase phase(full_gc ?
2019 ShenandoahPhaseTimings::full_gc_purge_par :
2020 ShenandoahPhaseTimings::purge_par);
2021 ShenandoahIsAliveSelector is_alive;
2022 uint num_workers = _workers->active_workers();
2023 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
2024 _workers->run_task(&unlink_task);
2025 }
2026
2027 {
2028 ShenandoahGCPhase phase(full_gc ?
2029 ShenandoahPhaseTimings::full_gc_purge_cldg :
2030 ShenandoahPhaseTimings::purge_cldg);
2031 ClassLoaderDataGraph::purge();
2032 }
2033 // Resize and verify metaspace
2034 MetaspaceGC::compute_new_size();
2035 MetaspaceUtils::verify_metrics();
2036 }
2037
2038 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
2039 // so they should not have forwarded oops.
2040 // However, we do need to "null" dead oops in the roots, if can not be done
2041 // in concurrent cycles.
2042 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
2043 ShenandoahGCPhase root_phase(full_gc ?
2044 ShenandoahPhaseTimings::full_gc_purge :
2045 ShenandoahPhaseTimings::purge);
2046 uint num_workers = _workers->active_workers();
2047 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
2048 ShenandoahPhaseTimings::full_gc_purge_par :
2049 ShenandoahPhaseTimings::purge_par;
2050 ShenandoahGCPhase phase(timing_phase);
2051
2052 // Cleanup weak roots
2053 if (has_forwarded_objects()) {
2054 if (is_traversal_mode()) {
2055 ShenandoahForwardedIsAliveClosure is_alive;
2056 ShenandoahTraversalUpdateRefsClosure keep_alive;
2057 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahTraversalUpdateRefsClosure>
2058 cleaning_task(&is_alive, &keep_alive, num_workers);
2059 _workers->run_task(&cleaning_task);
2060 } else {
2061 ShenandoahForwardedIsAliveClosure is_alive;
2062 ShenandoahUpdateRefsClosure keep_alive;
2063 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2064 cleaning_task(&is_alive, &keep_alive, num_workers);
2065 _workers->run_task(&cleaning_task);
2066 }
2067 } else {
2068 ShenandoahIsAliveClosure is_alive;
2069 #ifdef ASSERT
2070 ShenandoahAssertNotForwardedClosure verify_cl;
2071 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2072 cleaning_task(&is_alive, &verify_cl, num_workers);
2073 #else
2074 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2075 cleaning_task(&is_alive, &do_nothing_cl, num_workers);
2076 #endif
2077 _workers->run_task(&cleaning_task);
2078 }
2079 }
2080
2081 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2082 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2083 stw_process_weak_roots(full_gc);
2084 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2085 stw_unload_classes(full_gc);
2086 }
2087 }
2088
2089 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2090 if (is_traversal_mode()) {
2091 set_gc_state_mask(HAS_FORWARDED | UPDATEREFS, cond);
2092 } else {
2093 set_gc_state_mask(HAS_FORWARDED, cond);
2094 }
2095
2096 }
2097
2098 void ShenandoahHeap::set_process_references(bool pr) {
2099 _process_references.set_cond(pr);
2100 }
2101
2102 void ShenandoahHeap::set_unload_classes(bool uc) {
2103 _unload_classes.set_cond(uc);
2104 }
2105
2106 bool ShenandoahHeap::process_references() const {
2107 return _process_references.is_set();
2108 }
2109
2110 bool ShenandoahHeap::unload_classes() const {
2111 return _unload_classes.is_set();
2112 }
2113
2114 address ShenandoahHeap::in_cset_fast_test_addr() {
2115 ShenandoahHeap* heap = ShenandoahHeap::heap();
2116 assert(heap->collection_set() != NULL, "Sanity");
2117 return (address) heap->collection_set()->biased_map_address();
2118 }
2119
2120 address ShenandoahHeap::cancelled_gc_addr() {
2121 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
2122 }
2123
2124 address ShenandoahHeap::gc_state_addr() {
2125 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2126 }
2127
2128 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2129 return Atomic::load_acquire(&_bytes_allocated_since_gc_start);
2130 }
2131
2132 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2133 Atomic::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2134 }
2135
2136 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2137 _degenerated_gc_in_progress.set_cond(in_progress);
2138 }
2139
2140 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2141 _full_gc_in_progress.set_cond(in_progress);
2142 }
2143
2144 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2145 assert (is_full_gc_in_progress(), "should be");
2146 _full_gc_move_in_progress.set_cond(in_progress);
2147 }
2148
2149 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2150 set_gc_state_mask(UPDATEREFS, in_progress);
2151 }
2152
2153 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2154 ShenandoahCodeRoots::register_nmethod(nm);
2155 }
2156
2157 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2158 ShenandoahCodeRoots::unregister_nmethod(nm);
2159 }
2160
2161 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
2162 ShenandoahCodeRoots::flush_nmethod(nm);
2163 }
2164
2165 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2166 heap_region_containing(o)->record_pin();
2167 return o;
2168 }
2169
2170 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2171 heap_region_containing(o)->record_unpin();
2172 }
2173
2174 void ShenandoahHeap::sync_pinned_region_status() {
2175 ShenandoahHeapLocker locker(lock());
2176
2177 for (size_t i = 0; i < num_regions(); i++) {
2178 ShenandoahHeapRegion *r = get_region(i);
2179 if (r->is_active()) {
2180 if (r->is_pinned()) {
2181 if (r->pin_count() == 0) {
2182 r->make_unpinned();
2183 }
2184 } else {
2185 if (r->pin_count() > 0) {
2186 r->make_pinned();
2187 }
2188 }
2189 }
2190 }
2191
2192 assert_pinned_region_status();
2193 }
2194
2195 #ifdef ASSERT
2196 void ShenandoahHeap::assert_pinned_region_status() {
2197 for (size_t i = 0; i < num_regions(); i++) {
2198 ShenandoahHeapRegion* r = get_region(i);
2199 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2200 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2201 }
2202 }
2203 #endif
2204
2205 GCTimer* ShenandoahHeap::gc_timer() const {
2206 return _gc_timer;
2207 }
2208
2209 void ShenandoahHeap::prepare_concurrent_roots() {
2210 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2211 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
2212 set_concurrent_root_in_progress(true);
2213 }
2214 }
2215
2216 void ShenandoahHeap::prepare_concurrent_unloading() {
2217 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2218 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2219 _unloader.prepare();
2220 }
2221 }
2222
2223 void ShenandoahHeap::finish_concurrent_unloading() {
2224 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2225 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2226 _unloader.finish();
2227 }
2228 }
2229
2230 #ifdef ASSERT
2231 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2232 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2233
2234 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2235 if (UseDynamicNumberOfGCThreads ||
2236 (FLAG_IS_DEFAULT(ParallelGCThreads) && ForceDynamicNumberOfGCThreads)) {
2237 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2238 } else {
2239 // Use ParallelGCThreads inside safepoints
2240 assert(nworkers == ParallelGCThreads, "Use ParalleGCThreads within safepoints");
2241 }
2242 } else {
2243 if (UseDynamicNumberOfGCThreads ||
2244 (FLAG_IS_DEFAULT(ConcGCThreads) && ForceDynamicNumberOfGCThreads)) {
2245 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2246 } else {
2247 // Use ConcGCThreads outside safepoints
2248 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2249 }
2250 }
2251 }
2252 #endif
2253
2254 ShenandoahVerifier* ShenandoahHeap::verifier() {
2255 guarantee(ShenandoahVerify, "Should be enabled");
2256 assert (_verifier != NULL, "sanity");
2257 return _verifier;
2258 }
2259
2260 template<class T>
2261 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2262 private:
2263 T cl;
2264 ShenandoahHeap* _heap;
2265 ShenandoahRegionIterator* _regions;
2266 bool _concurrent;
2267 public:
2268 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2269 AbstractGangTask("Concurrent Update References Task"),
2270 cl(T()),
2271 _heap(ShenandoahHeap::heap()),
2272 _regions(regions),
2273 _concurrent(concurrent) {
2274 }
2275
2276 void work(uint worker_id) {
2277 if (_concurrent) {
2278 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2279 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2280 do_work();
2281 } else {
2282 ShenandoahParallelWorkerSession worker_session(worker_id);
2283 do_work();
2284 }
2285 }
2286
2287 private:
2288 void do_work() {
2289 ShenandoahHeapRegion* r = _regions->next();
2290 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2291 while (r != NULL) {
2292 HeapWord* update_watermark = r->get_update_watermark();
2293 assert (update_watermark >= r->bottom(), "sanity");
2294 if (r->is_active() && !r->is_cset()) {
2295 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2296 }
2297 if (ShenandoahPacing) {
2298 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2299 }
2300 if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
2301 return;
2302 }
2303 r = _regions->next();
2304 }
2305 }
2306 };
2307
2308 void ShenandoahHeap::update_heap_references(bool concurrent) {
2309 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
2310 workers()->run_task(&task);
2311 }
2312
2313 void ShenandoahHeap::op_init_updaterefs() {
2314 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2315
2316 set_evacuation_in_progress(false);
2317
2318 {
2319 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_retire_gclabs);
2320 retire_and_reset_gclabs();
2321 }
2322
2323 if (ShenandoahVerify) {
2324 if (!is_degenerated_gc_in_progress()) {
2325 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots);
2326 }
2327 verifier()->verify_before_updaterefs();
2328 }
2329
2330 set_update_refs_in_progress(true);
2331
2332 {
2333 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_prepare);
2334
2335 make_parsable(true);
2336
2337 // Reset iterator.
2338 _update_refs_iterator.reset();
2339 }
2340
2341 if (ShenandoahPacing) {
2342 pacer()->setup_for_updaterefs();
2343 }
2344 }
2345
2346 void ShenandoahHeap::op_final_updaterefs() {
2347 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2348
2349 finish_concurrent_unloading();
2350
2351 // Check if there is left-over work, and finish it
2352 if (_update_refs_iterator.has_next()) {
2353 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2354
2355 // Finish updating references where we left off.
2356 clear_cancelled_gc();
2357 update_heap_references(false);
2358 }
2359
2360 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2361 // everything. On degenerated paths, cancelled gc would not be set anyway.
2362 if (cancelled_gc()) {
2363 clear_cancelled_gc();
2364 }
2365 assert(!cancelled_gc(), "Should have been done right before");
2366
2367 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2368 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2369 }
2370
2371 if (is_degenerated_gc_in_progress()) {
2372 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2373 } else {
2374 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2375 }
2376
2377 // Has to be done before cset is clear
2378 if (ShenandoahVerify) {
2379 verifier()->verify_roots_in_to_space();
2380 }
2381
2382 // Drop unnecessary "pinned" state from regions that does not have CP marks
2383 // anymore, as this would allow trashing them below.
2384 {
2385 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_sync_pinned);
2386 sync_pinned_region_status();
2387 }
2388
2389 {
2390 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2391 trash_cset_regions();
2392 }
2393
2394 set_has_forwarded_objects(false);
2395 set_update_refs_in_progress(false);
2396
2397 if (ShenandoahVerify) {
2398 verifier()->verify_after_updaterefs();
2399 }
2400
2401 if (VerifyAfterGC) {
2402 Universe::verify();
2403 }
2404
2405 {
2406 ShenandoahHeapLocker locker(lock());
2407 _free_set->rebuild();
2408 }
2409 }
2410
2411 #ifdef ASSERT
2412 void ShenandoahHeap::assert_heaplock_owned_by_current_thread() {
2413 _lock.assert_owned_by_current_thread();
2414 }
2415
2416 void ShenandoahHeap::assert_heaplock_not_owned_by_current_thread() {
2417 _lock.assert_not_owned_by_current_thread();
2418 }
2419
2420 void ShenandoahHeap::assert_heaplock_or_safepoint() {
2421 _lock.assert_owned_by_current_thread_or_safepoint();
2422 }
2423 #endif
2424
2425 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2426 print_on(st);
2427 print_heap_regions_on(st);
2428 }
2429
2430 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2431 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2432
2433 size_t regions_from = _bitmap_regions_per_slice * slice;
2434 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2435 for (size_t g = regions_from; g < regions_to; g++) {
2436 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2437 if (skip_self && g == r->region_number()) continue;
2438 if (get_region(g)->is_committed()) {
2439 return true;
2440 }
2441 }
2442 return false;
2443 }
2444
2445 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2446 assert_heaplock_owned_by_current_thread();
2447
2448 // Bitmaps in special regions do not need commits
2449 if (_bitmap_region_special) {
2450 return true;
2451 }
2452
2453 if (is_bitmap_slice_committed(r, true)) {
2454 // Some other region from the group is already committed, meaning the bitmap
2455 // slice is already committed, we exit right away.
2456 return true;
2457 }
2458
2459 // Commit the bitmap slice:
2460 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2461 size_t off = _bitmap_bytes_per_slice * slice;
2462 size_t len = _bitmap_bytes_per_slice;
2463 if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) {
2464 return false;
2465 }
2466 return true;
2467 }
2468
2469 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2470 assert_heaplock_owned_by_current_thread();
2471
2472 // Bitmaps in special regions do not need uncommits
2473 if (_bitmap_region_special) {
2474 return true;
2475 }
2476
2477 if (is_bitmap_slice_committed(r, true)) {
2478 // Some other region from the group is still committed, meaning the bitmap
2479 // slice is should stay committed, exit right away.
2480 return true;
2481 }
2482
2483 // Uncommit the bitmap slice:
2484 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2485 size_t off = _bitmap_bytes_per_slice * slice;
2486 size_t len = _bitmap_bytes_per_slice;
2487 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2488 return false;
2489 }
2490 return true;
2491 }
2492
2493 void ShenandoahHeap::safepoint_synchronize_begin() {
2494 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2495 SuspendibleThreadSet::synchronize();
2496 }
2497 }
2498
2499 void ShenandoahHeap::safepoint_synchronize_end() {
2500 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2501 SuspendibleThreadSet::desynchronize();
2502 }
2503 }
2504
2505 void ShenandoahHeap::vmop_entry_init_mark() {
2506 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2507 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2508 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
2509
2510 try_inject_alloc_failure();
2511 VM_ShenandoahInitMark op;
2512 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2513 }
2514
2515 void ShenandoahHeap::vmop_entry_final_mark() {
2516 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2517 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2518 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
2519
2520 try_inject_alloc_failure();
2521 VM_ShenandoahFinalMarkStartEvac op;
2522 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2523 }
2524
2525 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2526 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2527 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2528 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
2529
2530 try_inject_alloc_failure();
2531 VM_ShenandoahInitUpdateRefs op;
2532 VMThread::execute(&op);
2533 }
2534
2535 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2536 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2537 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2538 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
2539
2540 try_inject_alloc_failure();
2541 VM_ShenandoahFinalUpdateRefs op;
2542 VMThread::execute(&op);
2543 }
2544
2545 void ShenandoahHeap::vmop_entry_init_traversal() {
2546 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2547 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2548 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc_gross);
2549
2550 try_inject_alloc_failure();
2551 VM_ShenandoahInitTraversalGC op;
2552 VMThread::execute(&op);
2553 }
2554
2555 void ShenandoahHeap::vmop_entry_final_traversal() {
2556 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2557 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2558 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc_gross);
2559
2560 try_inject_alloc_failure();
2561 VM_ShenandoahFinalTraversalGC op;
2562 VMThread::execute(&op);
2563 }
2564
2565 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2566 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2567 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2568 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
2569
2570 try_inject_alloc_failure();
2571 VM_ShenandoahFullGC op(cause);
2572 VMThread::execute(&op);
2573 }
2574
2575 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2576 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2577 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2578 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
2579
2580 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2581 VMThread::execute(°enerated_gc);
2582 }
2583
2584 void ShenandoahHeap::entry_init_mark() {
2585 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2586 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
2587 const char* msg = init_mark_event_message();
2588 GCTraceTime(Info, gc) time(msg, gc_timer());
2589 EventMark em("%s", msg);
2590
2591 ShenandoahWorkerScope scope(workers(),
2592 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2593 "init marking");
2594
2595 op_init_mark();
2596 }
2597
2598 void ShenandoahHeap::entry_final_mark() {
2599 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2600 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
2601 const char* msg = final_mark_event_message();
2602 GCTraceTime(Info, gc) time(msg, gc_timer());
2603 EventMark em("%s", msg);
2604
2605 ShenandoahWorkerScope scope(workers(),
2606 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2607 "final marking");
2608
2609 op_final_mark();
2610 }
2611
2612 void ShenandoahHeap::entry_init_updaterefs() {
2613 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2614 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
2615
2616 static const char* msg = "Pause Init Update Refs";
2617 GCTraceTime(Info, gc) time(msg, gc_timer());
2618 EventMark em("%s", msg);
2619
2620 // No workers used in this phase, no setup required
2621
2622 op_init_updaterefs();
2623 }
2624
2625 void ShenandoahHeap::entry_final_updaterefs() {
2626 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2627 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
2628
2629 static const char* msg = "Pause Final Update Refs";
2630 GCTraceTime(Info, gc) time(msg, gc_timer());
2631 EventMark em("%s", msg);
2632
2633 ShenandoahWorkerScope scope(workers(),
2634 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2635 "final reference update");
2636
2637 op_final_updaterefs();
2638 }
2639
2640 void ShenandoahHeap::entry_init_traversal() {
2641 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2642 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc);
2643
2644 static const char* msg = init_traversal_event_message();
2645 GCTraceTime(Info, gc) time(msg, gc_timer());
2646 EventMark em("%s", msg);
2647
2648 ShenandoahWorkerScope scope(workers(),
2649 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2650 "init traversal");
2651
2652 op_init_traversal();
2653 }
2654
2655 void ShenandoahHeap::entry_final_traversal() {
2656 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2657 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc);
2658
2659 static const char* msg = final_traversal_event_message();
2660 GCTraceTime(Info, gc) time(msg, gc_timer());
2661 EventMark em("%s", msg);
2662
2663 ShenandoahWorkerScope scope(workers(),
2664 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2665 "final traversal");
2666
2667 op_final_traversal();
2668 }
2669
2670 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2671 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2672 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
2673
2674 static const char* msg = "Pause Full";
2675 GCTraceTime(Info, gc) time(msg, gc_timer(), cause, true);
2676 EventMark em("%s", msg);
2677
2678 ShenandoahWorkerScope scope(workers(),
2679 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2680 "full gc");
2681
2682 op_full(cause);
2683 }
2684
2685 void ShenandoahHeap::entry_degenerated(int point) {
2686 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2687 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
2688
2689 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2690 const char* msg = degen_event_message(dpoint);
2691 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2692 EventMark em("%s", msg);
2693
2694 ShenandoahWorkerScope scope(workers(),
2695 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2696 "stw degenerated gc");
2697
2698 set_degenerated_gc_in_progress(true);
2699 op_degenerated(dpoint);
2700 set_degenerated_gc_in_progress(false);
2701 }
2702
2703 void ShenandoahHeap::entry_mark() {
2704 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2705
2706 const char* msg = conc_mark_event_message();
2707 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2708 EventMark em("%s", msg);
2709
2710 ShenandoahWorkerScope scope(workers(),
2711 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2712 "concurrent marking");
2713
2714 try_inject_alloc_failure();
2715 op_mark();
2716 }
2717
2718 void ShenandoahHeap::entry_evac() {
2719 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
2720 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2721
2722 static const char* msg = "Concurrent evacuation";
2723 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2724 EventMark em("%s", msg);
2725
2726 ShenandoahWorkerScope scope(workers(),
2727 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2728 "concurrent evacuation");
2729
2730 try_inject_alloc_failure();
2731 op_conc_evac();
2732 }
2733
2734 void ShenandoahHeap::entry_updaterefs() {
2735 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
2736
2737 static const char* msg = "Concurrent update references";
2738 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2739 EventMark em("%s", msg);
2740
2741 ShenandoahWorkerScope scope(workers(),
2742 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2743 "concurrent reference update");
2744
2745 try_inject_alloc_failure();
2746 op_updaterefs();
2747 }
2748
2749 void ShenandoahHeap::entry_roots() {
2750 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_roots);
2751
2752 static const char* msg = "Concurrent roots processing";
2753 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2754 EventMark em("%s", msg);
2755
2756 ShenandoahWorkerScope scope(workers(),
2757 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2758 "concurrent root processing");
2759
2760 try_inject_alloc_failure();
2761 op_roots();
2762 }
2763
2764 void ShenandoahHeap::entry_cleanup() {
2765 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup);
2766
2767 static const char* msg = "Concurrent cleanup";
2768 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2769 EventMark em("%s", msg);
2770
2771 // This phase does not use workers, no need for setup
2772
2773 try_inject_alloc_failure();
2774 op_cleanup();
2775 }
2776
2777 void ShenandoahHeap::entry_reset() {
2778 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset);
2779
2780 static const char* msg = "Concurrent reset";
2781 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2782 EventMark em("%s", msg);
2783
2784 ShenandoahWorkerScope scope(workers(),
2785 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2786 "concurrent reset");
2787
2788 try_inject_alloc_failure();
2789 op_reset();
2790 }
2791
2792 void ShenandoahHeap::entry_preclean() {
2793 if (ShenandoahPreclean && process_references()) {
2794 static const char* msg = "Concurrent precleaning";
2795 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2796 EventMark em("%s", msg);
2797
2798 ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
2799
2800 ShenandoahWorkerScope scope(workers(),
2801 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2802 "concurrent preclean",
2803 /* check_workers = */ false);
2804
2805 try_inject_alloc_failure();
2806 op_preclean();
2807 }
2808 }
2809
2810 void ShenandoahHeap::entry_traversal() {
2811 static const char* msg = conc_traversal_event_message();
2812 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2813 EventMark em("%s", msg);
2814
2815 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2816
2817 ShenandoahWorkerScope scope(workers(),
2818 ShenandoahWorkerPolicy::calc_workers_for_conc_traversal(),
2819 "concurrent traversal");
2820
2821 try_inject_alloc_failure();
2822 op_traversal();
2823 }
2824
2825 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2826 static const char *msg = "Concurrent uncommit";
2827 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2828 EventMark em("%s", msg);
2829
2830 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit);
2831
2832 op_uncommit(shrink_before);
2833 }
2834
2835 void ShenandoahHeap::try_inject_alloc_failure() {
2836 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2837 _inject_alloc_failure.set();
2838 os::naked_short_sleep(1);
2839 if (cancelled_gc()) {
2840 log_info(gc)("Allocation failure was successfully injected");
2841 }
2842 }
2843 }
2844
2845 bool ShenandoahHeap::should_inject_alloc_failure() {
2846 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2847 }
2848
2849 void ShenandoahHeap::initialize_serviceability() {
2850 _memory_pool = new ShenandoahMemoryPool(this);
2851 _cycle_memory_manager.add_pool(_memory_pool);
2852 _stw_memory_manager.add_pool(_memory_pool);
2853 }
2854
2855 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2856 GrowableArray<GCMemoryManager*> memory_managers(2);
2857 memory_managers.append(&_cycle_memory_manager);
2858 memory_managers.append(&_stw_memory_manager);
2859 return memory_managers;
2860 }
2861
2862 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2863 GrowableArray<MemoryPool*> memory_pools(1);
2864 memory_pools.append(_memory_pool);
2865 return memory_pools;
2866 }
2867
2868 MemoryUsage ShenandoahHeap::memory_usage() {
2869 return _memory_pool->get_memory_usage();
2870 }
2871
2872 void ShenandoahHeap::enter_evacuation() {
2873 _oom_evac_handler.enter_evacuation();
2874 }
2875
2876 void ShenandoahHeap::leave_evacuation() {
2877 _oom_evac_handler.leave_evacuation();
2878 }
2879
2880 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2881 _heap(ShenandoahHeap::heap()),
2882 _index(0) {}
2883
2884 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2885 _heap(heap),
2886 _index(0) {}
2887
2888 void ShenandoahRegionIterator::reset() {
2889 _index = 0;
2890 }
2891
2892 bool ShenandoahRegionIterator::has_next() const {
2893 return _index < _heap->num_regions();
2894 }
2895
2896 char ShenandoahHeap::gc_state() const {
2897 return _gc_state.raw_value();
2898 }
2899
2900 void ShenandoahHeap::deduplicate_string(oop str) {
2901 assert(java_lang_String::is_instance(str), "invariant");
2902
2903 if (ShenandoahStringDedup::is_enabled()) {
2904 ShenandoahStringDedup::deduplicate(str);
2905 }
2906 }
2907
2908 const char* ShenandoahHeap::init_mark_event_message() const {
2909 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
2910
2911 bool proc_refs = process_references();
2912 bool unload_cls = unload_classes();
2913
2914 if (proc_refs && unload_cls) {
2915 return "Pause Init Mark (process weakrefs) (unload classes)";
2916 } else if (proc_refs) {
2917 return "Pause Init Mark (process weakrefs)";
2918 } else if (unload_cls) {
2919 return "Pause Init Mark (unload classes)";
2920 } else {
2921 return "Pause Init Mark";
2922 }
2923 }
2924
2925 const char* ShenandoahHeap::final_mark_event_message() const {
2926 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
2927
2928 bool proc_refs = process_references();
2929 bool unload_cls = unload_classes();
2930
2931 if (proc_refs && unload_cls) {
2932 return "Pause Final Mark (process weakrefs) (unload classes)";
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 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
2944
2945 bool proc_refs = process_references();
2946 bool unload_cls = unload_classes();
2947
2948 if (proc_refs && unload_cls) {
2949 return "Concurrent marking (process weakrefs) (unload classes)";
2950 } else if (proc_refs) {
2951 return "Concurrent marking (process weakrefs)";
2952 } else if (unload_cls) {
2953 return "Concurrent marking (unload classes)";
2954 } else {
2955 return "Concurrent marking";
2956 }
2957 }
2958
2959 const char* ShenandoahHeap::init_traversal_event_message() const {
2960 bool proc_refs = process_references();
2961 bool unload_cls = unload_classes();
2962
2963 if (proc_refs && unload_cls) {
2964 return "Pause Init Traversal (process weakrefs) (unload classes)";
2965 } else if (proc_refs) {
2966 return "Pause Init Traversal (process weakrefs)";
2967 } else if (unload_cls) {
2968 return "Pause Init Traversal (unload classes)";
2969 } else {
2970 return "Pause Init Traversal";
2971 }
2972 }
2973
2974 const char* ShenandoahHeap::final_traversal_event_message() const {
2975 bool proc_refs = process_references();
2976 bool unload_cls = unload_classes();
2977
2978 if (proc_refs && unload_cls) {
2979 return "Pause Final Traversal (process weakrefs) (unload classes)";
2980 } else if (proc_refs) {
2981 return "Pause Final Traversal (process weakrefs)";
2982 } else if (unload_cls) {
2983 return "Pause Final Traversal (unload classes)";
2984 } else {
2985 return "Pause Final Traversal";
2986 }
2987 }
2988
2989 const char* ShenandoahHeap::conc_traversal_event_message() const {
2990 bool proc_refs = process_references();
2991 bool unload_cls = unload_classes();
2992
2993 if (proc_refs && unload_cls) {
2994 return "Concurrent Traversal (process weakrefs) (unload classes)";
2995 } else if (proc_refs) {
2996 return "Concurrent Traversal (process weakrefs)";
2997 } else if (unload_cls) {
2998 return "Concurrent Traversal (unload classes)";
2999 } else {
3000 return "Concurrent Traversal";
3001 }
3002 }
3003
3004 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
3005 switch (point) {
3006 case _degenerated_unset:
3007 return "Pause Degenerated GC (<UNSET>)";
3008 case _degenerated_traversal:
3009 return "Pause Degenerated GC (Traversal)";
3010 case _degenerated_outside_cycle:
3011 return "Pause Degenerated GC (Outside of Cycle)";
3012 case _degenerated_mark:
3013 return "Pause Degenerated GC (Mark)";
3014 case _degenerated_evac:
3015 return "Pause Degenerated GC (Evacuation)";
3016 case _degenerated_updaterefs:
3017 return "Pause Degenerated GC (Update Refs)";
3018 default:
3019 ShouldNotReachHere();
3020 return "ERROR";
3021 }
3022 }
3023
3024 jushort* ShenandoahHeap::get_liveness_cache(uint worker_id) {
3025 #ifdef ASSERT
3026 assert(_liveness_cache != NULL, "sanity");
3027 assert(worker_id < _max_workers, "sanity");
3028 for (uint i = 0; i < num_regions(); i++) {
3029 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
3030 }
3031 #endif
3032 return _liveness_cache[worker_id];
3033 }
3034
3035 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
3036 assert(worker_id < _max_workers, "sanity");
3037 assert(_liveness_cache != NULL, "sanity");
3038 jushort* ld = _liveness_cache[worker_id];
3039 for (uint i = 0; i < num_regions(); i++) {
3040 ShenandoahHeapRegion* r = get_region(i);
3041 jushort live = ld[i];
3042 if (live > 0) {
3043 r->increase_live_data_gc_words(live);
3044 ld[i] = 0;
3045 }
3046 }
3047 }