1 /*
2 * Copyright (c) 2013, 2019, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #include "precompiled.hpp"
25 #include "memory/allocation.hpp"
26 #include "memory/universe.hpp"
27
28 #include "gc/shared/gcArguments.hpp"
29 #include "gc/shared/gcTimer.hpp"
30 #include "gc/shared/gcTraceTime.inline.hpp"
31 #include "gc/shared/locationPrinter.inline.hpp"
32 #include "gc/shared/memAllocator.hpp"
33 #include "gc/shared/plab.hpp"
34
35 #include "gc/shenandoah/shenandoahAllocTracker.hpp"
36 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
37 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
38 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
39 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
40 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
41 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
42 #include "gc/shenandoah/shenandoahControlThread.hpp"
43 #include "gc/shenandoah/shenandoahFreeSet.hpp"
44 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
45 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
46 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
47 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
48 #include "gc/shenandoah/shenandoahMarkCompact.hpp"
49 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
50 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
51 #include "gc/shenandoah/shenandoahMetrics.hpp"
52 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
53 #include "gc/shenandoah/shenandoahNormalMode.hpp"
54 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
55 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
56 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
57 #include "gc/shenandoah/shenandoahPassiveMode.hpp"
58 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
59 #include "gc/shenandoah/shenandoahStringDedup.hpp"
60 #include "gc/shenandoah/shenandoahTaskqueue.hpp"
61 #include "gc/shenandoah/shenandoahTraversalMode.hpp"
62 #include "gc/shenandoah/shenandoahUtils.hpp"
63 #include "gc/shenandoah/shenandoahVerifier.hpp"
64 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
65 #include "gc/shenandoah/shenandoahVMOperations.hpp"
66 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
67 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
68 #if INCLUDE_JFR
69 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
70 #endif
71
72 #include "memory/metaspace.hpp"
73 #include "oops/compressedOops.inline.hpp"
74 #include "runtime/globals.hpp"
75 #include "runtime/interfaceSupport.inline.hpp"
76 #include "runtime/safepointMechanism.hpp"
77 #include "runtime/vmThread.hpp"
78 #include "services/mallocTracker.hpp"
79
80 #ifdef ASSERT
81 template <class T>
82 void ShenandoahAssertToSpaceClosure::do_oop_work(T* p) {
83 T o = RawAccess<>::oop_load(p);
84 if (! CompressedOops::is_null(o)) {
85 oop obj = CompressedOops::decode_not_null(o);
86 shenandoah_assert_not_forwarded(p, obj);
87 }
88 }
89
90 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_work(p); }
91 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_work(p); }
92 #endif
93
94 class ShenandoahPretouchHeapTask : public AbstractGangTask {
95 private:
96 ShenandoahRegionIterator _regions;
97 const size_t _page_size;
98 public:
99 ShenandoahPretouchHeapTask(size_t page_size) :
100 AbstractGangTask("Shenandoah Pretouch Heap"),
101 _page_size(page_size) {}
102
103 virtual void work(uint worker_id) {
104 ShenandoahHeapRegion* r = _regions.next();
105 while (r != NULL) {
106 os::pretouch_memory(r->bottom(), r->end(), _page_size);
107 r = _regions.next();
108 }
109 }
110 };
111
112 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
113 private:
114 ShenandoahRegionIterator _regions;
115 char* _bitmap_base;
116 const size_t _bitmap_size;
117 const size_t _page_size;
118 public:
119 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
120 AbstractGangTask("Shenandoah Pretouch Bitmap"),
121 _bitmap_base(bitmap_base),
122 _bitmap_size(bitmap_size),
123 _page_size(page_size) {}
124
125 virtual void work(uint worker_id) {
126 ShenandoahHeapRegion* r = _regions.next();
127 while (r != NULL) {
128 size_t start = r->region_number() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
129 size_t end = (r->region_number() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
130 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
131
132 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
133
134 r = _regions.next();
135 }
136 }
137 };
138
139 jint ShenandoahHeap::initialize() {
140 initialize_heuristics();
141
142 //
143 // Figure out heap sizing
144 //
145
146 size_t init_byte_size = InitialHeapSize;
147 size_t min_byte_size = MinHeapSize;
148 size_t max_byte_size = MaxHeapSize;
149 size_t heap_alignment = HeapAlignment;
150
151 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
152
153 if (ShenandoahAlwaysPreTouch) {
154 // Enabled pre-touch means the entire heap is committed right away.
155 init_byte_size = max_byte_size;
156 }
157
158 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
159 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
160
161 _num_regions = ShenandoahHeapRegion::region_count();
162
163 size_t num_committed_regions = init_byte_size / reg_size_bytes;
164 num_committed_regions = MIN2(num_committed_regions, _num_regions);
165 assert(num_committed_regions <= _num_regions, "sanity");
166 _initial_size = num_committed_regions * reg_size_bytes;
167
168 size_t num_min_regions = min_byte_size / reg_size_bytes;
169 num_min_regions = MIN2(num_min_regions, _num_regions);
170 assert(num_min_regions <= _num_regions, "sanity");
171 _minimum_size = num_min_regions * reg_size_bytes;
172
173 _committed = _initial_size;
174
175 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
176 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
177
178 //
179 // Reserve and commit memory for heap
180 //
181
182 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
183 initialize_reserved_region(heap_rs);
184 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
185 _heap_region_special = heap_rs.special();
186
187 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
188 "Misaligned heap: " PTR_FORMAT, p2i(base()));
189
190 #if SHENANDOAH_OPTIMIZED_OBJTASK
191 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
192 // Fail if we ever attempt to address more than we can.
193 if ((uintptr_t)heap_rs.end() >= ObjArrayChunkedTask::max_addressable()) {
194 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
195 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
196 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
197 p2i(heap_rs.base()), p2i(heap_rs.end()), ObjArrayChunkedTask::max_addressable());
198 vm_exit_during_initialization("Fatal Error", buf);
199 }
200 #endif
201
202 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
203 if (!_heap_region_special) {
204 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
205 "Cannot commit heap memory");
206 }
207
208 //
209 // Reserve and commit memory for bitmap(s)
210 //
211
212 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
213 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
214
215 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
216
217 guarantee(bitmap_bytes_per_region != 0,
218 "Bitmap bytes per region should not be zero");
219 guarantee(is_power_of_2(bitmap_bytes_per_region),
220 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
221
222 if (bitmap_page_size > bitmap_bytes_per_region) {
223 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
224 _bitmap_bytes_per_slice = bitmap_page_size;
225 } else {
226 _bitmap_regions_per_slice = 1;
227 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
228 }
229
230 guarantee(_bitmap_regions_per_slice >= 1,
231 "Should have at least one region per slice: " SIZE_FORMAT,
232 _bitmap_regions_per_slice);
233
234 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
235 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
236 _bitmap_bytes_per_slice, bitmap_page_size);
237
238 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
239 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
240 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
241 _bitmap_region_special = bitmap.special();
242
243 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
244 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
245 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
246 if (!_bitmap_region_special) {
247 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
248 "Cannot commit bitmap memory");
249 }
250
251 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
252
253 if (ShenandoahVerify) {
254 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
255 if (!verify_bitmap.special()) {
256 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
257 "Cannot commit verification bitmap memory");
258 }
259 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
260 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
261 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
262 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
263 }
264
265 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
266 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
267 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
268 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
269 _aux_bitmap_region_special = aux_bitmap.special();
270 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
271
272 //
273 // Create regions and region sets
274 //
275
276 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
277 _free_set = new ShenandoahFreeSet(this, _num_regions);
278 _collection_set = new ShenandoahCollectionSet(this, sh_rs.base(), sh_rs.size());
279
280 {
281 ShenandoahHeapLocker locker(lock());
282
283 size_t size_words = ShenandoahHeapRegion::region_size_words();
284
285 for (size_t i = 0; i < _num_regions; i++) {
286 HeapWord* start = (HeapWord*)sh_rs.base() + size_words * i;
287 bool is_committed = i < num_committed_regions;
288 ShenandoahHeapRegion* r = new ShenandoahHeapRegion(this, start, size_words, i, is_committed);
289
290 _marking_context->initialize_top_at_mark_start(r);
291 _regions[i] = r;
292 assert(!collection_set()->is_in(i), "New region should not be in collection set");
293 }
294
295 // Initialize to complete
296 _marking_context->mark_complete();
297
298 _free_set->rebuild();
299 }
300
301 if (ShenandoahAlwaysPreTouch) {
302 assert(!AlwaysPreTouch, "Should have been overridden");
303
304 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
305 // before initialize() below zeroes it with initializing thread. For any given region,
306 // we touch the region and the corresponding bitmaps from the same thread.
307 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
308
309 size_t pretouch_heap_page_size = heap_page_size;
310 size_t pretouch_bitmap_page_size = bitmap_page_size;
311
312 #ifdef LINUX
313 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
314 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
315 // them into huge one. Therefore, we need to pretouch with smaller pages.
316 if (UseTransparentHugePages) {
317 pretouch_heap_page_size = (size_t)os::vm_page_size();
318 pretouch_bitmap_page_size = (size_t)os::vm_page_size();
319 }
320 #endif
321
322 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
323 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
324
325 log_info(gc, init)("Pretouch bitmap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
326 _num_regions, pretouch_bitmap_page_size);
327 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, pretouch_bitmap_page_size);
328 _workers->run_task(&bcl);
329
330 log_info(gc, init)("Pretouch heap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
331 _num_regions, pretouch_heap_page_size);
332 ShenandoahPretouchHeapTask hcl(pretouch_heap_page_size);
333 _workers->run_task(&hcl);
334 }
335
336 //
337 // Initialize the rest of GC subsystems
338 //
339
340 _liveness_cache = NEW_C_HEAP_ARRAY(jushort*, _max_workers, mtGC);
341 for (uint worker = 0; worker < _max_workers; worker++) {
342 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(jushort, _num_regions, mtGC);
343 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(jushort));
344 }
345
346 // There should probably be Shenandoah-specific options for these,
347 // just as there are G1-specific options.
348 {
349 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
350 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
351 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
352 }
353
354 _monitoring_support = new ShenandoahMonitoringSupport(this);
355 _phase_timings = new ShenandoahPhaseTimings();
356 ShenandoahStringDedup::initialize();
357 ShenandoahCodeRoots::initialize();
358
359 if (ShenandoahAllocationTrace) {
360 _alloc_tracker = new ShenandoahAllocTracker();
361 }
362
363 if (ShenandoahPacing) {
364 _pacer = new ShenandoahPacer(this);
365 _pacer->setup_for_idle();
366 } else {
367 _pacer = NULL;
368 }
369
370 _traversal_gc = strcmp(ShenandoahGCMode, "traversal") == 0 ?
371 new ShenandoahTraversalGC(this, _num_regions) :
372 NULL;
373
374 _control_thread = new ShenandoahControlThread();
375
376 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max",
377 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size),
378 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size),
379 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity())
380 );
381
382 log_info(gc, init)("Safepointing mechanism: %s",
383 SafepointMechanism::uses_thread_local_poll() ? "thread-local poll" :
384 (SafepointMechanism::uses_global_page_poll() ? "global-page poll" : "unknown"));
385
386 return JNI_OK;
387 }
388
389 void ShenandoahHeap::initialize_heuristics() {
390 if (ShenandoahGCMode != NULL) {
391 if (strcmp(ShenandoahGCMode, "traversal") == 0) {
392 _gc_mode = new ShenandoahTraversalMode();
393 } else if (strcmp(ShenandoahGCMode, "normal") == 0) {
394 _gc_mode = new ShenandoahNormalMode();
395 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
396 _gc_mode = new ShenandoahPassiveMode();
397 } else {
398 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
399 }
400 } else {
401 ShouldNotReachHere();
402 }
403 _gc_mode->initialize_flags();
404 _heuristics = _gc_mode->initialize_heuristics();
405
406 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
407 vm_exit_during_initialization(
408 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
409 _heuristics->name()));
410 }
411 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
412 vm_exit_during_initialization(
413 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
414 _heuristics->name()));
415 }
416 log_info(gc, init)("Shenandoah heuristics: %s",
417 _heuristics->name());
418 }
419
420 #ifdef _MSC_VER
421 #pragma warning( push )
422 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
423 #endif
424
425 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
426 CollectedHeap(),
427 _initial_size(0),
428 _used(0),
429 _committed(0),
430 _bytes_allocated_since_gc_start(0),
431 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
432 _workers(NULL),
433 _safepoint_workers(NULL),
434 _heap_region_special(false),
435 _num_regions(0),
436 _regions(NULL),
437 _update_refs_iterator(this),
438 _control_thread(NULL),
439 _shenandoah_policy(policy),
440 _heuristics(NULL),
441 _free_set(NULL),
442 _scm(new ShenandoahConcurrentMark()),
443 _traversal_gc(NULL),
444 _full_gc(new ShenandoahMarkCompact()),
445 _pacer(NULL),
446 _verifier(NULL),
447 _alloc_tracker(NULL),
448 _phase_timings(NULL),
449 _monitoring_support(NULL),
450 _memory_pool(NULL),
451 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
452 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
453 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
454 _soft_ref_policy(),
455 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
456 _ref_processor(NULL),
457 _marking_context(NULL),
458 _bitmap_size(0),
459 _bitmap_regions_per_slice(0),
460 _bitmap_bytes_per_slice(0),
461 _bitmap_region_special(false),
462 _aux_bitmap_region_special(false),
463 _liveness_cache(NULL),
464 _collection_set(NULL)
465 {
466 log_info(gc, init)("GC threads: " UINT32_FORMAT " parallel, " UINT32_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
467 log_info(gc, init)("Reference processing: %s", ParallelRefProcEnabled ? "parallel" : "serial");
468
469 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
470
471 _max_workers = MAX2(_max_workers, 1U);
472 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
473 /* are_GC_task_threads */ true,
474 /* are_ConcurrentGC_threads */ true);
475 if (_workers == NULL) {
476 vm_exit_during_initialization("Failed necessary allocation.");
477 } else {
478 _workers->initialize_workers();
479 }
480
481 if (ShenandoahParallelSafepointThreads > 1) {
482 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
483 ShenandoahParallelSafepointThreads,
484 /* are_GC_task_threads */ false,
485 /* are_ConcurrentGC_threads */ false);
486 _safepoint_workers->initialize_workers();
487 }
488 }
489
490 #ifdef _MSC_VER
491 #pragma warning( pop )
492 #endif
493
494 class ShenandoahResetBitmapTask : public AbstractGangTask {
495 private:
496 ShenandoahRegionIterator _regions;
497
498 public:
499 ShenandoahResetBitmapTask() :
500 AbstractGangTask("Parallel Reset Bitmap Task") {}
501
502 void work(uint worker_id) {
503 ShenandoahHeapRegion* region = _regions.next();
504 ShenandoahHeap* heap = ShenandoahHeap::heap();
505 ShenandoahMarkingContext* const ctx = heap->marking_context();
506 while (region != NULL) {
507 if (heap->is_bitmap_slice_committed(region)) {
508 ctx->clear_bitmap(region);
509 }
510 region = _regions.next();
511 }
512 }
513 };
514
515 void ShenandoahHeap::reset_mark_bitmap() {
516 assert_gc_workers(_workers->active_workers());
517 mark_incomplete_marking_context();
518
519 ShenandoahResetBitmapTask task;
520 _workers->run_task(&task);
521 }
522
523 void ShenandoahHeap::print_on(outputStream* st) const {
524 st->print_cr("Shenandoah Heap");
525 st->print_cr(" " SIZE_FORMAT "%s total, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
526 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
527 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
528 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
529 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
530 num_regions(),
531 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
532 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
533
534 st->print("Status: ");
535 if (has_forwarded_objects()) st->print("has forwarded objects, ");
536 if (is_concurrent_mark_in_progress()) st->print("marking, ");
537 if (is_evacuation_in_progress()) st->print("evacuating, ");
538 if (is_update_refs_in_progress()) st->print("updating refs, ");
539 if (is_concurrent_traversal_in_progress()) st->print("traversal, ");
540 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
541 if (is_full_gc_in_progress()) st->print("full gc, ");
542 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
543
544 if (cancelled_gc()) {
545 st->print("cancelled");
546 } else {
547 st->print("not cancelled");
548 }
549 st->cr();
550
551 st->print_cr("Reserved region:");
552 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
553 p2i(reserved_region().start()),
554 p2i(reserved_region().end()));
555
556 ShenandoahCollectionSet* cset = collection_set();
557 st->print_cr("Collection set:");
558 if (cset != NULL) {
559 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
560 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
561 } else {
562 st->print_cr(" (NULL)");
563 }
564
565 st->cr();
566 MetaspaceUtils::print_on(st);
567
568 if (Verbose) {
569 print_heap_regions_on(st);
570 }
571 }
572
573 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
574 public:
575 void do_thread(Thread* thread) {
576 assert(thread != NULL, "Sanity");
577 assert(thread->is_Worker_thread(), "Only worker thread expected");
578 ShenandoahThreadLocalData::initialize_gclab(thread);
579 }
580 };
581
582 void ShenandoahHeap::post_initialize() {
583 CollectedHeap::post_initialize();
584 MutexLocker ml(Threads_lock);
585
586 ShenandoahInitWorkerGCLABClosure init_gclabs;
587 _workers->threads_do(&init_gclabs);
588
589 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
590 // Now, we will let WorkGang to initialize gclab when new worker is created.
591 _workers->set_initialize_gclab();
592
593 _scm->initialize(_max_workers);
594 _full_gc->initialize(_gc_timer);
595
596 ref_processing_init();
597
598 _heuristics->initialize();
599
600 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
601 }
602
603 size_t ShenandoahHeap::used() const {
604 return Atomic::load_acquire(&_used);
605 }
606
607 size_t ShenandoahHeap::committed() const {
608 OrderAccess::acquire();
609 return _committed;
610 }
611
612 void ShenandoahHeap::increase_committed(size_t bytes) {
613 assert_heaplock_or_safepoint();
614 _committed += bytes;
615 }
616
617 void ShenandoahHeap::decrease_committed(size_t bytes) {
618 assert_heaplock_or_safepoint();
619 _committed -= bytes;
620 }
621
622 void ShenandoahHeap::increase_used(size_t bytes) {
623 Atomic::add(bytes, &_used);
624 }
625
626 void ShenandoahHeap::set_used(size_t bytes) {
627 Atomic::release_store_fence(&_used, bytes);
628 }
629
630 void ShenandoahHeap::decrease_used(size_t bytes) {
631 assert(used() >= bytes, "never decrease heap size by more than we've left");
632 Atomic::sub(bytes, &_used);
633 }
634
635 void ShenandoahHeap::increase_allocated(size_t bytes) {
636 Atomic::add(bytes, &_bytes_allocated_since_gc_start);
637 }
638
639 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
640 size_t bytes = words * HeapWordSize;
641 if (!waste) {
642 increase_used(bytes);
643 }
644 increase_allocated(bytes);
645 if (ShenandoahPacing) {
646 control_thread()->pacing_notify_alloc(words);
647 if (waste) {
648 pacer()->claim_for_alloc(words, true);
649 }
650 }
651 }
652
653 size_t ShenandoahHeap::capacity() const {
654 return committed();
655 }
656
657 size_t ShenandoahHeap::max_capacity() const {
658 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
659 }
660
661 size_t ShenandoahHeap::min_capacity() const {
662 return _minimum_size;
663 }
664
665 size_t ShenandoahHeap::initial_capacity() const {
666 return _initial_size;
667 }
668
669 bool ShenandoahHeap::is_in(const void* p) const {
670 HeapWord* heap_base = (HeapWord*) base();
671 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
672 return p >= heap_base && p < last_region_end;
673 }
674
675 void ShenandoahHeap::op_uncommit(double shrink_before) {
676 assert (ShenandoahUncommit, "should be enabled");
677
678 // Application allocates from the beginning of the heap, and GC allocates at
679 // the end of it. It is more efficient to uncommit from the end, so that applications
680 // could enjoy the near committed regions. GC allocations are much less frequent,
681 // and therefore can accept the committing costs.
682
683 size_t count = 0;
684 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
685 ShenandoahHeapRegion* r = get_region(i - 1);
686 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
687 ShenandoahHeapLocker locker(lock());
688 if (r->is_empty_committed()) {
689 // Do not uncommit below minimal capacity
690 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
691 break;
692 }
693
694 r->make_uncommitted();
695 count++;
696 }
697 }
698 SpinPause(); // allow allocators to take the lock
699 }
700
701 if (count > 0) {
702 control_thread()->notify_heap_changed();
703 }
704 }
705
706 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
707 // New object should fit the GCLAB size
708 size_t min_size = MAX2(size, PLAB::min_size());
709
710 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
711 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
712 new_size = MIN2(new_size, PLAB::max_size());
713 new_size = MAX2(new_size, PLAB::min_size());
714
715 // Record new heuristic value even if we take any shortcut. This captures
716 // the case when moderately-sized objects always take a shortcut. At some point,
717 // heuristics should catch up with them.
718 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
719
720 if (new_size < size) {
721 // New size still does not fit the object. Fall back to shared allocation.
722 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
723 return NULL;
724 }
725
726 // Retire current GCLAB, and allocate a new one.
727 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
728 gclab->retire();
729
730 size_t actual_size = 0;
731 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
732 if (gclab_buf == NULL) {
733 return NULL;
734 }
735
736 assert (size <= actual_size, "allocation should fit");
737
738 if (ZeroTLAB) {
739 // ..and clear it.
740 Copy::zero_to_words(gclab_buf, actual_size);
741 } else {
742 // ...and zap just allocated object.
743 #ifdef ASSERT
744 // Skip mangling the space corresponding to the object header to
745 // ensure that the returned space is not considered parsable by
746 // any concurrent GC thread.
747 size_t hdr_size = oopDesc::header_size();
748 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
749 #endif // ASSERT
750 }
751 gclab->set_buf(gclab_buf, actual_size);
752 return gclab->allocate(size);
753 }
754
755 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
756 size_t requested_size,
757 size_t* actual_size) {
758 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
759 HeapWord* res = allocate_memory(req);
760 if (res != NULL) {
761 *actual_size = req.actual_size();
762 } else {
763 *actual_size = 0;
764 }
765 return res;
766 }
767
768 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
769 size_t word_size,
770 size_t* actual_size) {
771 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
772 HeapWord* res = allocate_memory(req);
773 if (res != NULL) {
774 *actual_size = req.actual_size();
775 } else {
776 *actual_size = 0;
777 }
778 return res;
779 }
780
781 ShenandoahHeap* ShenandoahHeap::heap() {
782 CollectedHeap* heap = Universe::heap();
783 assert(heap != NULL, "Unitialized access to ShenandoahHeap::heap()");
784 assert(heap->kind() == CollectedHeap::Shenandoah, "not a shenandoah heap");
785 return (ShenandoahHeap*) heap;
786 }
787
788 ShenandoahHeap* ShenandoahHeap::heap_no_check() {
789 CollectedHeap* heap = Universe::heap();
790 return (ShenandoahHeap*) heap;
791 }
792
793 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
794 ShenandoahAllocTrace trace_alloc(req.size(), req.type());
795
796 intptr_t pacer_epoch = 0;
797 bool in_new_region = false;
798 HeapWord* result = NULL;
799
800 if (req.is_mutator_alloc()) {
801 if (ShenandoahPacing) {
802 pacer()->pace_for_alloc(req.size());
803 pacer_epoch = pacer()->epoch();
804 }
805
806 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
807 result = allocate_memory_under_lock(req, in_new_region);
808 }
809
810 // Allocation failed, block until control thread reacted, then retry allocation.
811 //
812 // It might happen that one of the threads requesting allocation would unblock
813 // way later after GC happened, only to fail the second allocation, because
814 // other threads have already depleted the free storage. In this case, a better
815 // strategy is to try again, as long as GC makes progress.
816 //
817 // Then, we need to make sure the allocation was retried after at least one
818 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
819
820 size_t tries = 0;
821
822 while (result == NULL && _progress_last_gc.is_set()) {
823 tries++;
824 control_thread()->handle_alloc_failure(req.size());
825 result = allocate_memory_under_lock(req, in_new_region);
826 }
827
828 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
829 tries++;
830 control_thread()->handle_alloc_failure(req.size());
831 result = allocate_memory_under_lock(req, in_new_region);
832 }
833
834 } else {
835 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
836 result = allocate_memory_under_lock(req, in_new_region);
837 // Do not call handle_alloc_failure() here, because we cannot block.
838 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
839 }
840
841 if (in_new_region) {
842 control_thread()->notify_heap_changed();
843 }
844
845 if (result != NULL) {
846 size_t requested = req.size();
847 size_t actual = req.actual_size();
848
849 assert (req.is_lab_alloc() || (requested == actual),
850 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
851 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
852
853 if (req.is_mutator_alloc()) {
854 notify_mutator_alloc_words(actual, false);
855
856 // If we requested more than we were granted, give the rest back to pacer.
857 // This only matters if we are in the same pacing epoch: do not try to unpace
858 // over the budget for the other phase.
859 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
860 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
861 }
862 } else {
863 increase_used(actual*HeapWordSize);
864 }
865 }
866
867 return result;
868 }
869
870 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
871 ShenandoahHeapLocker locker(lock());
872 return _free_set->allocate(req, in_new_region);
873 }
874
875 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
876 bool* gc_overhead_limit_was_exceeded) {
877 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
878 return allocate_memory(req);
879 }
880
881 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
882 size_t size,
883 Metaspace::MetadataType mdtype) {
884 MetaWord* result;
885
886 // Inform metaspace OOM to GC heuristics if class unloading is possible.
887 if (heuristics()->can_unload_classes()) {
888 ShenandoahHeuristics* h = heuristics();
889 h->record_metaspace_oom();
890 }
891
892 // Expand and retry allocation
893 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
894 if (result != NULL) {
895 return result;
896 }
897
898 // Start full GC
899 collect(GCCause::_metadata_GC_clear_soft_refs);
900
901 // Retry allocation
902 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
903 if (result != NULL) {
904 return result;
905 }
906
907 // Expand and retry allocation
908 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
909 if (result != NULL) {
910 return result;
911 }
912
913 // Out of memory
914 return NULL;
915 }
916
917 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
918 private:
919 ShenandoahHeap* const _heap;
920 Thread* const _thread;
921 public:
922 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
923 _heap(heap), _thread(Thread::current()) {}
924
925 void do_object(oop p) {
926 shenandoah_assert_marked(NULL, p);
927 if (!p->is_forwarded()) {
928 _heap->evacuate_object(p, _thread);
929 }
930 }
931 };
932
933 class ShenandoahEvacuationTask : public AbstractGangTask {
934 private:
935 ShenandoahHeap* const _sh;
936 ShenandoahCollectionSet* const _cs;
937 bool _concurrent;
938 public:
939 ShenandoahEvacuationTask(ShenandoahHeap* sh,
940 ShenandoahCollectionSet* cs,
941 bool concurrent) :
942 AbstractGangTask("Parallel Evacuation Task"),
943 _sh(sh),
944 _cs(cs),
945 _concurrent(concurrent)
946 {}
947
948 void work(uint worker_id) {
949 if (_concurrent) {
950 ShenandoahConcurrentWorkerSession worker_session(worker_id);
951 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
952 ShenandoahEvacOOMScope oom_evac_scope;
953 do_work();
954 } else {
955 ShenandoahParallelWorkerSession worker_session(worker_id);
956 ShenandoahEvacOOMScope oom_evac_scope;
957 do_work();
958 }
959 }
960
961 private:
962 void do_work() {
963 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
964 ShenandoahHeapRegion* r;
965 while ((r =_cs->claim_next()) != NULL) {
966 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->region_number());
967 _sh->marked_object_iterate(r, &cl);
968
969 if (ShenandoahPacing) {
970 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
971 }
972
973 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
974 break;
975 }
976 }
977 }
978 };
979
980 void ShenandoahHeap::trash_cset_regions() {
981 ShenandoahHeapLocker locker(lock());
982
983 ShenandoahCollectionSet* set = collection_set();
984 ShenandoahHeapRegion* r;
985 set->clear_current_index();
986 while ((r = set->next()) != NULL) {
987 r->make_trash();
988 }
989 collection_set()->clear();
990 }
991
992 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
993 st->print_cr("Heap Regions:");
994 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
995 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
996 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start (previous, next)");
997 st->print_cr("SN=alloc sequence numbers (first mutator, last mutator, first gc, last gc)");
998
999 for (size_t i = 0; i < num_regions(); i++) {
1000 get_region(i)->print_on(st);
1001 }
1002 }
1003
1004 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1005 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1006
1007 oop humongous_obj = oop(start->bottom());
1008 size_t size = humongous_obj->size();
1009 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1010 size_t index = start->region_number() + required_regions - 1;
1011
1012 assert(!start->has_live(), "liveness must be zero");
1013
1014 for(size_t i = 0; i < required_regions; i++) {
1015 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1016 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1017 ShenandoahHeapRegion* region = get_region(index --);
1018
1019 assert(region->is_humongous(), "expect correct humongous start or continuation");
1020 assert(!region->is_cset(), "Humongous region should not be in collection set");
1021
1022 region->make_trash_immediate();
1023 }
1024 }
1025
1026 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1027 public:
1028 void do_thread(Thread* thread) {
1029 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1030 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1031 gclab->retire();
1032 }
1033 };
1034
1035 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
1036 if (UseTLAB) {
1037 CollectedHeap::ensure_parsability(retire_tlabs);
1038 }
1039 ShenandoahRetireGCLABClosure cl;
1040 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1041 cl.do_thread(t);
1042 }
1043 workers()->threads_do(&cl);
1044 }
1045
1046 void ShenandoahHeap::resize_tlabs() {
1047 CollectedHeap::resize_all_tlabs();
1048 }
1049
1050 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1051 private:
1052 ShenandoahRootEvacuator* _rp;
1053
1054 public:
1055 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1056 AbstractGangTask("Shenandoah evacuate and update roots"),
1057 _rp(rp) {}
1058
1059 void work(uint worker_id) {
1060 ShenandoahParallelWorkerSession worker_session(worker_id);
1061 ShenandoahEvacOOMScope oom_evac_scope;
1062 ShenandoahEvacuateUpdateRootsClosure cl;
1063 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1064 _rp->roots_do(worker_id, &cl);
1065 }
1066 };
1067
1068 void ShenandoahHeap::evacuate_and_update_roots() {
1069 #if COMPILER2_OR_JVMCI
1070 DerivedPointerTable::clear();
1071 #endif
1072 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1073 {
1074 // Include concurrent roots if current cycle can not process those roots concurrently
1075 ShenandoahRootEvacuator rp(workers()->active_workers(),
1076 ShenandoahPhaseTimings::init_evac,
1077 !ShenandoahConcurrentRoots::should_do_concurrent_roots());
1078 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1079 workers()->run_task(&roots_task);
1080 }
1081
1082 #if COMPILER2_OR_JVMCI
1083 DerivedPointerTable::update_pointers();
1084 #endif
1085 }
1086
1087 // Returns size in bytes
1088 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1089 if (ShenandoahElasticTLAB) {
1090 // With Elastic TLABs, return the max allowed size, and let the allocation path
1091 // figure out the safe size for current allocation.
1092 return ShenandoahHeapRegion::max_tlab_size_bytes();
1093 } else {
1094 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1095 }
1096 }
1097
1098 size_t ShenandoahHeap::max_tlab_size() const {
1099 // Returns size in words
1100 return ShenandoahHeapRegion::max_tlab_size_words();
1101 }
1102
1103 class ShenandoahRetireAndResetGCLABClosure : public ThreadClosure {
1104 public:
1105 void do_thread(Thread* thread) {
1106 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1107 gclab->retire();
1108 if (ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1109 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1110 }
1111 }
1112 };
1113
1114 void ShenandoahHeap::retire_and_reset_gclabs() {
1115 ShenandoahRetireAndResetGCLABClosure cl;
1116 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1117 cl.do_thread(t);
1118 }
1119 workers()->threads_do(&cl);
1120 }
1121
1122 void ShenandoahHeap::collect(GCCause::Cause cause) {
1123 control_thread()->request_gc(cause);
1124 }
1125
1126 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1127 //assert(false, "Shouldn't need to do full collections");
1128 }
1129
1130 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1131 Space* sp = heap_region_containing(addr);
1132 if (sp != NULL) {
1133 return sp->block_start(addr);
1134 }
1135 return NULL;
1136 }
1137
1138 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1139 Space* sp = heap_region_containing(addr);
1140 return sp->block_is_obj(addr);
1141 }
1142
1143 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1144 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1145 }
1146
1147 jlong ShenandoahHeap::millis_since_last_gc() {
1148 double v = heuristics()->time_since_last_gc() * 1000;
1149 assert(0 <= v && v <= max_jlong, "value should fit: %f", v);
1150 return (jlong)v;
1151 }
1152
1153 void ShenandoahHeap::prepare_for_verify() {
1154 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1155 make_parsable(false);
1156 }
1157 }
1158
1159 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1160 workers()->print_worker_threads_on(st);
1161 if (ShenandoahStringDedup::is_enabled()) {
1162 ShenandoahStringDedup::print_worker_threads_on(st);
1163 }
1164 }
1165
1166 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1167 workers()->threads_do(tcl);
1168 if (_safepoint_workers != NULL) {
1169 _safepoint_workers->threads_do(tcl);
1170 }
1171 if (ShenandoahStringDedup::is_enabled()) {
1172 ShenandoahStringDedup::threads_do(tcl);
1173 }
1174 }
1175
1176 void ShenandoahHeap::print_tracing_info() const {
1177 LogTarget(Info, gc, stats) lt;
1178 if (lt.is_enabled()) {
1179 ResourceMark rm;
1180 LogStream ls(lt);
1181
1182 phase_timings()->print_on(&ls);
1183
1184 ls.cr();
1185 ls.cr();
1186
1187 shenandoah_policy()->print_gc_stats(&ls);
1188
1189 ls.cr();
1190 ls.cr();
1191
1192 if (ShenandoahPacing) {
1193 pacer()->print_on(&ls);
1194 }
1195
1196 ls.cr();
1197 ls.cr();
1198
1199 if (ShenandoahAllocationTrace) {
1200 assert(alloc_tracker() != NULL, "Must be");
1201 alloc_tracker()->print_on(&ls);
1202 } else {
1203 ls.print_cr(" Allocation tracing is disabled, use -XX:+ShenandoahAllocationTrace to enable.");
1204 }
1205 }
1206 }
1207
1208 void ShenandoahHeap::verify(VerifyOption vo) {
1209 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1210 if (ShenandoahVerify) {
1211 verifier()->verify_generic(vo);
1212 } else {
1213 // TODO: Consider allocating verification bitmaps on demand,
1214 // and turn this on unconditionally.
1215 }
1216 }
1217 }
1218 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1219 return _free_set->capacity();
1220 }
1221
1222 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1223 private:
1224 MarkBitMap* _bitmap;
1225 Stack<oop,mtGC>* _oop_stack;
1226
1227 template <class T>
1228 void do_oop_work(T* p) {
1229 T o = RawAccess<>::oop_load(p);
1230 if (!CompressedOops::is_null(o)) {
1231 oop obj = CompressedOops::decode_not_null(o);
1232 oop fwd = (oop) ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
1233 if (fwd == NULL) {
1234 // There is an odd interaction with VM_HeapWalkOperation, see jvmtiTagMap.cpp.
1235 //
1236 // That operation walks the reachable objects on its own, storing the marking
1237 // wavefront in the object marks. When it is done, it calls the CollectedHeap
1238 // to iterate over all objects to clean up the mess. When it reaches here,
1239 // the Shenandoah fwdptr resolution code encounters the marked objects with
1240 // NULL forwardee. Trying to act on that would crash the VM. Or fail the
1241 // asserts, should we go for resolve_forwarded_pointer(obj).
1242 //
1243 // Therefore, we have to dodge it by doing the raw access to forwardee, and
1244 // assuming the object had no forwardee, if that thing is NULL.
1245 } else {
1246 obj = fwd;
1247 }
1248 assert(oopDesc::is_oop(obj), "must be a valid oop");
1249 if (!_bitmap->is_marked((HeapWord*) obj)) {
1250 _bitmap->mark((HeapWord*) obj);
1251 _oop_stack->push(obj);
1252 }
1253 }
1254 }
1255 public:
1256 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1257 _bitmap(bitmap), _oop_stack(oop_stack) {}
1258 void do_oop(oop* p) { do_oop_work(p); }
1259 void do_oop(narrowOop* p) { do_oop_work(p); }
1260 };
1261
1262 /*
1263 * This is public API, used in preparation of object_iterate().
1264 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1265 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1266 * control, we call SH::make_tlabs_parsable().
1267 */
1268 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1269 // No-op.
1270 }
1271
1272 /*
1273 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1274 *
1275 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1276 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1277 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1278 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1279 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1280 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1281 * wiped the bitmap in preparation for next marking).
1282 *
1283 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1284 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1285 * is allowed to report dead objects, but is not required to do so.
1286 */
1287 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1288 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1289 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1290 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1291 return;
1292 }
1293
1294 // Reset bitmap
1295 _aux_bit_map.clear();
1296
1297 Stack<oop,mtGC> oop_stack;
1298
1299 // First, we process GC roots according to current GC cycle. This populates the work stack with initial objects.
1300 ShenandoahHeapIterationRootScanner rp;
1301 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1302
1303 // If we are unloading classes right now, we should not touch weak roots,
1304 // on the off-chance we would evacuate them and make them live accidentally.
1305 // In other cases, we have to scan all roots.
1306 if (is_evacuation_in_progress() && unload_classes()) {
1307 rp.strong_roots_do(&oops);
1308 } else {
1309 rp.roots_do(&oops);
1310 }
1311
1312 // Work through the oop stack to traverse heap.
1313 while (! oop_stack.is_empty()) {
1314 oop obj = oop_stack.pop();
1315 assert(oopDesc::is_oop(obj), "must be a valid oop");
1316 cl->do_object(obj);
1317 obj->oop_iterate(&oops);
1318 }
1319
1320 assert(oop_stack.is_empty(), "should be empty");
1321
1322 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1323 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1324 }
1325 }
1326
1327 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1328 for (size_t i = 0; i < num_regions(); i++) {
1329 ShenandoahHeapRegion* current = get_region(i);
1330 blk->heap_region_do(current);
1331 }
1332 }
1333
1334 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1335 private:
1336 ShenandoahHeap* const _heap;
1337 ShenandoahHeapRegionClosure* const _blk;
1338
1339 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));
1340 volatile size_t _index;
1341 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
1342
1343 public:
1344 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1345 AbstractGangTask("Parallel Region Task"),
1346 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1347
1348 void work(uint worker_id) {
1349 size_t stride = ShenandoahParallelRegionStride;
1350
1351 size_t max = _heap->num_regions();
1352 while (_index < max) {
1353 size_t cur = Atomic::add(stride, &_index) - stride;
1354 size_t start = cur;
1355 size_t end = MIN2(cur + stride, max);
1356 if (start >= max) break;
1357
1358 for (size_t i = cur; i < end; i++) {
1359 ShenandoahHeapRegion* current = _heap->get_region(i);
1360 _blk->heap_region_do(current);
1361 }
1362 }
1363 }
1364 };
1365
1366 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1367 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1368 if (num_regions() > ShenandoahParallelRegionStride) {
1369 ShenandoahParallelHeapRegionTask task(blk);
1370 workers()->run_task(&task);
1371 } else {
1372 heap_region_iterate(blk);
1373 }
1374 }
1375
1376 class ShenandoahClearLivenessClosure : public ShenandoahHeapRegionClosure {
1377 private:
1378 ShenandoahMarkingContext* const _ctx;
1379 public:
1380 ShenandoahClearLivenessClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1381
1382 void heap_region_do(ShenandoahHeapRegion* r) {
1383 if (r->is_active()) {
1384 r->clear_live_data();
1385 _ctx->capture_top_at_mark_start(r);
1386 } else {
1387 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1388 assert(_ctx->top_at_mark_start(r) == r->top(),
1389 "Region " SIZE_FORMAT " should already have correct TAMS", r->region_number());
1390 }
1391 }
1392
1393 bool is_thread_safe() { return true; }
1394 };
1395
1396 void ShenandoahHeap::op_init_mark() {
1397 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1398 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1399
1400 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1401 assert(!marking_context()->is_complete(), "should not be complete");
1402
1403 if (ShenandoahVerify) {
1404 verifier()->verify_before_concmark();
1405 }
1406
1407 if (VerifyBeforeGC) {
1408 Universe::verify();
1409 }
1410
1411 set_concurrent_mark_in_progress(true);
1412 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1413 {
1414 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1415 make_parsable(true);
1416 }
1417
1418 {
1419 ShenandoahGCPhase phase(ShenandoahPhaseTimings::clear_liveness);
1420 ShenandoahClearLivenessClosure clc;
1421 parallel_heap_region_iterate(&clc);
1422 }
1423
1424 // Make above changes visible to worker threads
1425 OrderAccess::fence();
1426
1427 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1428
1429 if (UseTLAB) {
1430 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1431 resize_tlabs();
1432 }
1433
1434 if (ShenandoahPacing) {
1435 pacer()->setup_for_mark();
1436 }
1437 }
1438
1439 void ShenandoahHeap::op_mark() {
1440 concurrent_mark()->mark_from_roots();
1441 }
1442
1443 class ShenandoahCompleteLivenessClosure : public ShenandoahHeapRegionClosure {
1444 private:
1445 ShenandoahMarkingContext* const _ctx;
1446 public:
1447 ShenandoahCompleteLivenessClosure() : _ctx(ShenandoahHeap::heap()->complete_marking_context()) {}
1448
1449 void heap_region_do(ShenandoahHeapRegion* r) {
1450 if (r->is_active()) {
1451 HeapWord *tams = _ctx->top_at_mark_start(r);
1452 HeapWord *top = r->top();
1453 if (top > tams) {
1454 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1455 }
1456 } else {
1457 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1458 assert(_ctx->top_at_mark_start(r) == r->top(),
1459 "Region " SIZE_FORMAT " should have correct TAMS", r->region_number());
1460 }
1461 }
1462
1463 bool is_thread_safe() { return true; }
1464 };
1465
1466 void ShenandoahHeap::op_final_mark() {
1467 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1468
1469 // It is critical that we
1470 // evacuate roots right after finishing marking, so that we don't
1471 // get unmarked objects in the roots.
1472
1473 if (!cancelled_gc()) {
1474 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1475
1476 // Marking is completed, deactivate SATB barrier
1477 set_concurrent_mark_in_progress(false);
1478 mark_complete_marking_context();
1479
1480 parallel_cleaning(false /* full gc*/);
1481
1482 if (has_forwarded_objects()) {
1483 // Degen may be caused by failed evacuation of roots
1484 if (is_degenerated_gc_in_progress()) {
1485 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
1486 } else {
1487 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::update_roots);
1488 }
1489 set_has_forwarded_objects(false);
1490 }
1491
1492 if (ShenandoahVerify) {
1493 verifier()->verify_roots_no_forwarded();
1494 }
1495 // All allocations past TAMS are implicitly live, adjust the region data.
1496 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1497 {
1498 ShenandoahGCPhase phase(ShenandoahPhaseTimings::complete_liveness);
1499 ShenandoahCompleteLivenessClosure cl;
1500 parallel_heap_region_iterate(&cl);
1501 }
1502
1503 // Force the threads to reacquire their TLABs outside the collection set.
1504 {
1505 ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs);
1506 make_parsable(true);
1507 }
1508
1509 // We are about to select the collection set, make sure it knows about
1510 // current pinning status. Also, this allows trashing more regions that
1511 // now have their pinning status dropped.
1512 {
1513 ShenandoahGCPhase phase(ShenandoahPhaseTimings::sync_pinned);
1514 sync_pinned_region_status();
1515 }
1516
1517 // Trash the collection set left over from previous cycle, if any.
1518 {
1519 ShenandoahGCPhase phase(ShenandoahPhaseTimings::trash_cset);
1520 trash_cset_regions();
1521 }
1522
1523 {
1524 ShenandoahGCPhase phase(ShenandoahPhaseTimings::prepare_evac);
1525
1526 ShenandoahHeapLocker locker(lock());
1527 _collection_set->clear();
1528 _free_set->clear();
1529
1530 heuristics()->choose_collection_set(_collection_set);
1531
1532 _free_set->rebuild();
1533 }
1534
1535 // If collection set has candidates, start evacuation.
1536 // Otherwise, bypass the rest of the cycle.
1537 if (!collection_set()->is_empty()) {
1538 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1539
1540 if (ShenandoahVerify) {
1541 verifier()->verify_before_evacuation();
1542 }
1543
1544 set_evacuation_in_progress(true);
1545 // From here on, we need to update references.
1546 set_has_forwarded_objects(true);
1547
1548 if (!is_degenerated_gc_in_progress()) {
1549 evacuate_and_update_roots();
1550 }
1551
1552 if (ShenandoahPacing) {
1553 pacer()->setup_for_evac();
1554 }
1555
1556 if (ShenandoahVerify) {
1557 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1558 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots);
1559 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots);
1560 verifier()->verify_roots_no_forwarded_except(types);
1561 } else {
1562 verifier()->verify_roots_no_forwarded();
1563 }
1564 verifier()->verify_during_evacuation();
1565 }
1566 } else {
1567 if (ShenandoahVerify) {
1568 verifier()->verify_after_concmark();
1569 }
1570
1571 if (VerifyAfterGC) {
1572 Universe::verify();
1573 }
1574 }
1575
1576 } else {
1577 // If this cycle was updating references, we need to keep the has_forwarded_objects
1578 // flag on, for subsequent phases to deal with it.
1579 concurrent_mark()->cancel();
1580 set_concurrent_mark_in_progress(false);
1581
1582 if (process_references()) {
1583 // Abandon reference processing right away: pre-cleaning must have failed.
1584 ReferenceProcessor *rp = ref_processor();
1585 rp->disable_discovery();
1586 rp->abandon_partial_discovery();
1587 rp->verify_no_references_recorded();
1588 }
1589 }
1590 }
1591
1592 void ShenandoahHeap::op_final_evac() {
1593 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1594
1595 set_evacuation_in_progress(false);
1596
1597 {
1598 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_retire_gclabs);
1599 retire_and_reset_gclabs();
1600 }
1601
1602 if (ShenandoahVerify) {
1603 verifier()->verify_after_evacuation();
1604 }
1605
1606 if (VerifyAfterGC) {
1607 Universe::verify();
1608 }
1609 }
1610
1611 void ShenandoahHeap::op_conc_evac() {
1612 ShenandoahEvacuationTask task(this, _collection_set, true);
1613 workers()->run_task(&task);
1614 }
1615
1616 void ShenandoahHeap::op_stw_evac() {
1617 ShenandoahEvacuationTask task(this, _collection_set, false);
1618 workers()->run_task(&task);
1619 }
1620
1621 void ShenandoahHeap::op_updaterefs() {
1622 update_heap_references(true);
1623 }
1624
1625 void ShenandoahHeap::op_cleanup() {
1626 free_set()->recycle_trash();
1627 }
1628
1629 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask {
1630 private:
1631 ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
1632 ShenandoahWeakRoots<true /*concurrent*/> _weak_roots;
1633 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots;
1634
1635 public:
1636 ShenandoahConcurrentRootsEvacUpdateTask() :
1637 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Roots Task") {
1638 }
1639
1640 void work(uint worker_id) {
1641 ShenandoahEvacOOMScope oom;
1642 {
1643 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
1644 // may race against OopStorage::release() calls.
1645 ShenandoahEvacUpdateOopStorageRootsClosure cl;
1646 _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1647 _weak_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1648 }
1649
1650 {
1651 ShenandoahEvacuateUpdateRootsClosure cl;
1652 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1653 _cld_roots.cld_do(&clds);
1654 }
1655 }
1656 };
1657
1658 void ShenandoahHeap::op_roots() {
1659 if (is_evacuation_in_progress() &&
1660 ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1661 ShenandoahConcurrentRootsEvacUpdateTask task;
1662 workers()->run_task(&task);
1663 }
1664 }
1665
1666 void ShenandoahHeap::op_reset() {
1667 reset_mark_bitmap();
1668 }
1669
1670 void ShenandoahHeap::op_preclean() {
1671 concurrent_mark()->preclean_weak_refs();
1672 }
1673
1674 void ShenandoahHeap::op_init_traversal() {
1675 traversal_gc()->init_traversal_collection();
1676 }
1677
1678 void ShenandoahHeap::op_traversal() {
1679 traversal_gc()->concurrent_traversal_collection();
1680 }
1681
1682 void ShenandoahHeap::op_final_traversal() {
1683 traversal_gc()->final_traversal_collection();
1684 }
1685
1686 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1687 ShenandoahMetricsSnapshot metrics;
1688 metrics.snap_before();
1689
1690 full_gc()->do_it(cause);
1691 if (UseTLAB) {
1692 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs);
1693 resize_all_tlabs();
1694 }
1695
1696 metrics.snap_after();
1697
1698 if (metrics.is_good_progress()) {
1699 _progress_last_gc.set();
1700 } else {
1701 // Nothing to do. Tell the allocation path that we have failed to make
1702 // progress, and it can finally fail.
1703 _progress_last_gc.unset();
1704 }
1705 }
1706
1707 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1708 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1709 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1710 // some phase, we have to upgrade the Degenerate GC to Full GC.
1711
1712 clear_cancelled_gc();
1713
1714 ShenandoahMetricsSnapshot metrics;
1715 metrics.snap_before();
1716
1717 switch (point) {
1718 case _degenerated_traversal:
1719 {
1720 // Drop the collection set. Note: this leaves some already forwarded objects
1721 // behind, which may be problematic, see comments for ShenandoahEvacAssist
1722 // workarounds in ShenandoahTraversalHeuristics.
1723
1724 ShenandoahHeapLocker locker(lock());
1725 collection_set()->clear_current_index();
1726 for (size_t i = 0; i < collection_set()->count(); i++) {
1727 ShenandoahHeapRegion* r = collection_set()->next();
1728 r->make_regular_bypass();
1729 }
1730 collection_set()->clear();
1731 }
1732 op_final_traversal();
1733 op_cleanup();
1734 return;
1735
1736 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1737 // but enters it at different points, depending on which concurrent phase had
1738 // degenerated.
1739
1740 case _degenerated_outside_cycle:
1741 // We have degenerated from outside the cycle, which means something is bad with
1742 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1743 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1744 // we can do the most aggressive degen cycle, which includes processing references and
1745 // class unloading, unless those features are explicitly disabled.
1746 //
1747 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1748 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1749 set_process_references(heuristics()->can_process_references());
1750 set_unload_classes(heuristics()->can_unload_classes());
1751
1752 if (is_traversal_mode()) {
1753 // Not possible to degenerate from here, upgrade to Full GC right away.
1754 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1755 op_degenerated_fail();
1756 return;
1757 }
1758
1759 op_reset();
1760
1761 op_init_mark();
1762 if (cancelled_gc()) {
1763 op_degenerated_fail();
1764 return;
1765 }
1766
1767 case _degenerated_mark:
1768 op_final_mark();
1769 if (cancelled_gc()) {
1770 op_degenerated_fail();
1771 return;
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::ref_processing_init() {
1922 assert(_max_workers > 0, "Sanity");
1923
1924 _ref_processor =
1925 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
1926 ParallelRefProcEnabled, // MT processing
1927 _max_workers, // Degree of MT processing
1928 true, // MT discovery
1929 _max_workers, // Degree of MT discovery
1930 false, // Reference discovery is not atomic
1931 NULL, // No closure, should be installed before use
1932 true); // Scale worker threads
1933
1934 shenandoah_assert_rp_isalive_not_installed();
1935 }
1936
1937 GCTracer* ShenandoahHeap::tracer() {
1938 return shenandoah_policy()->tracer();
1939 }
1940
1941 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1942 return _free_set->used();
1943 }
1944
1945 bool ShenandoahHeap::try_cancel_gc() {
1946 while (true) {
1947 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1948 if (prev == CANCELLABLE) return true;
1949 else if (prev == CANCELLED) return false;
1950 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
1951 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
1952 if (Thread::current()->is_Java_thread()) {
1953 // We need to provide a safepoint here, otherwise we might
1954 // spin forever if a SP is pending.
1955 ThreadBlockInVM sp(JavaThread::current());
1956 SpinPause();
1957 }
1958 }
1959 }
1960
1961 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1962 if (try_cancel_gc()) {
1963 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1964 log_info(gc)("%s", msg.buffer());
1965 Events::log(Thread::current(), "%s", msg.buffer());
1966 }
1967 }
1968
1969 uint ShenandoahHeap::max_workers() {
1970 return _max_workers;
1971 }
1972
1973 void ShenandoahHeap::stop() {
1974 // The shutdown sequence should be able to terminate when GC is running.
1975
1976 // Step 0. Notify policy to disable event recording.
1977 _shenandoah_policy->record_shutdown();
1978
1979 // Step 1. Notify control thread that we are in shutdown.
1980 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1981 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1982 control_thread()->prepare_for_graceful_shutdown();
1983
1984 // Step 2. Notify GC workers that we are cancelling GC.
1985 cancel_gc(GCCause::_shenandoah_stop_vm);
1986
1987 // Step 3. Wait until GC worker exits normally.
1988 control_thread()->stop();
1989
1990 // Step 4. Stop String Dedup thread if it is active
1991 if (ShenandoahStringDedup::is_enabled()) {
1992 ShenandoahStringDedup::stop();
1993 }
1994 }
1995
1996 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
1997 if (!unload_classes()) return;
1998 bool purged_class;
1999
2000 // Unload classes and purge SystemDictionary.
2001 {
2002 ShenandoahGCPhase phase(full_gc ?
2003 ShenandoahPhaseTimings::full_gc_purge_class_unload :
2004 ShenandoahPhaseTimings::purge_class_unload);
2005 purged_class = SystemDictionary::do_unloading(gc_timer());
2006 }
2007
2008 {
2009 ShenandoahGCPhase phase(full_gc ?
2010 ShenandoahPhaseTimings::full_gc_purge_par :
2011 ShenandoahPhaseTimings::purge_par);
2012 ShenandoahIsAliveSelector is_alive;
2013 uint num_workers = _workers->active_workers();
2014 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
2015 _workers->run_task(&unlink_task);
2016 }
2017
2018 {
2019 ShenandoahGCPhase phase(full_gc ?
2020 ShenandoahPhaseTimings::full_gc_purge_cldg :
2021 ShenandoahPhaseTimings::purge_cldg);
2022 ClassLoaderDataGraph::purge();
2023 }
2024 // Resize and verify metaspace
2025 MetaspaceGC::compute_new_size();
2026 MetaspaceUtils::verify_metrics();
2027 }
2028
2029 // Process leftover weak oops: update them, if needed or assert they do not
2030 // need updating otherwise.
2031 // Weak processor API requires us to visit the oops, even if we are not doing
2032 // anything to them.
2033 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
2034 ShenandoahGCPhase root_phase(full_gc ?
2035 ShenandoahPhaseTimings::full_gc_purge :
2036 ShenandoahPhaseTimings::purge);
2037 uint num_workers = _workers->active_workers();
2038 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
2039 ShenandoahPhaseTimings::full_gc_purge_par :
2040 ShenandoahPhaseTimings::purge_par;
2041 // Cleanup weak roots
2042 ShenandoahGCPhase phase(timing_phase);
2043 if (has_forwarded_objects()) {
2044 if (is_traversal_mode()) {
2045 ShenandoahForwardedIsAliveClosure is_alive;
2046 ShenandoahTraversalUpdateRefsClosure keep_alive;
2047 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahTraversalUpdateRefsClosure>
2048 cleaning_task(&is_alive, &keep_alive, num_workers);
2049 _workers->run_task(&cleaning_task);
2050 } else {
2051 ShenandoahForwardedIsAliveClosure is_alive;
2052 ShenandoahUpdateRefsClosure keep_alive;
2053 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2054 cleaning_task(&is_alive, &keep_alive, num_workers);
2055 _workers->run_task(&cleaning_task);
2056 }
2057 } else {
2058 ShenandoahIsAliveClosure is_alive;
2059 #ifdef ASSERT
2060 ShenandoahAssertNotForwardedClosure verify_cl;
2061 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2062 cleaning_task(&is_alive, &verify_cl, num_workers);
2063 #else
2064 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2065 cleaning_task(&is_alive, &do_nothing_cl, num_workers);
2066 #endif
2067 _workers->run_task(&cleaning_task);
2068 }
2069 }
2070
2071 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2072 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2073 stw_process_weak_roots(full_gc);
2074 stw_unload_classes(full_gc);
2075 }
2076
2077 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2078 if (is_traversal_mode()) {
2079 set_gc_state_mask(HAS_FORWARDED | UPDATEREFS, cond);
2080 } else {
2081 set_gc_state_mask(HAS_FORWARDED, cond);
2082 }
2083
2084 }
2085
2086 void ShenandoahHeap::set_process_references(bool pr) {
2087 _process_references.set_cond(pr);
2088 }
2089
2090 void ShenandoahHeap::set_unload_classes(bool uc) {
2091 _unload_classes.set_cond(uc);
2092 }
2093
2094 bool ShenandoahHeap::process_references() const {
2095 return _process_references.is_set();
2096 }
2097
2098 bool ShenandoahHeap::unload_classes() const {
2099 return _unload_classes.is_set();
2100 }
2101
2102 address ShenandoahHeap::in_cset_fast_test_addr() {
2103 ShenandoahHeap* heap = ShenandoahHeap::heap();
2104 assert(heap->collection_set() != NULL, "Sanity");
2105 return (address) heap->collection_set()->biased_map_address();
2106 }
2107
2108 address ShenandoahHeap::cancelled_gc_addr() {
2109 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
2110 }
2111
2112 address ShenandoahHeap::gc_state_addr() {
2113 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2114 }
2115
2116 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2117 return Atomic::load_acquire(&_bytes_allocated_since_gc_start);
2118 }
2119
2120 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2121 Atomic::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2122 }
2123
2124 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2125 _degenerated_gc_in_progress.set_cond(in_progress);
2126 }
2127
2128 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2129 _full_gc_in_progress.set_cond(in_progress);
2130 }
2131
2132 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2133 assert (is_full_gc_in_progress(), "should be");
2134 _full_gc_move_in_progress.set_cond(in_progress);
2135 }
2136
2137 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2138 set_gc_state_mask(UPDATEREFS, in_progress);
2139 }
2140
2141 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2142 ShenandoahCodeRoots::add_nmethod(nm);
2143 }
2144
2145 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2146 ShenandoahCodeRoots::remove_nmethod(nm);
2147 }
2148
2149 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2150 heap_region_containing(o)->record_pin();
2151 return o;
2152 }
2153
2154 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2155 heap_region_containing(o)->record_unpin();
2156 }
2157
2158 void ShenandoahHeap::sync_pinned_region_status() {
2159 ShenandoahHeapLocker locker(lock());
2160
2161 for (size_t i = 0; i < num_regions(); i++) {
2162 ShenandoahHeapRegion *r = get_region(i);
2163 if (r->is_active()) {
2164 if (r->is_pinned()) {
2165 if (r->pin_count() == 0) {
2166 r->make_unpinned();
2167 }
2168 } else {
2169 if (r->pin_count() > 0) {
2170 r->make_pinned();
2171 }
2172 }
2173 }
2174 }
2175
2176 assert_pinned_region_status();
2177 }
2178
2179 #ifdef ASSERT
2180 void ShenandoahHeap::assert_pinned_region_status() {
2181 for (size_t i = 0; i < num_regions(); i++) {
2182 ShenandoahHeapRegion* r = get_region(i);
2183 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2184 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2185 }
2186 }
2187 #endif
2188
2189 GCTimer* ShenandoahHeap::gc_timer() const {
2190 return _gc_timer;
2191 }
2192
2193 #ifdef ASSERT
2194 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2195 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2196
2197 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2198 if (UseDynamicNumberOfGCThreads ||
2199 (FLAG_IS_DEFAULT(ParallelGCThreads) && ForceDynamicNumberOfGCThreads)) {
2200 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2201 } else {
2202 // Use ParallelGCThreads inside safepoints
2203 assert(nworkers == ParallelGCThreads, "Use ParalleGCThreads within safepoints");
2204 }
2205 } else {
2206 if (UseDynamicNumberOfGCThreads ||
2207 (FLAG_IS_DEFAULT(ConcGCThreads) && ForceDynamicNumberOfGCThreads)) {
2208 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2209 } else {
2210 // Use ConcGCThreads outside safepoints
2211 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2212 }
2213 }
2214 }
2215 #endif
2216
2217 ShenandoahVerifier* ShenandoahHeap::verifier() {
2218 guarantee(ShenandoahVerify, "Should be enabled");
2219 assert (_verifier != NULL, "sanity");
2220 return _verifier;
2221 }
2222
2223 template<class T>
2224 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2225 private:
2226 T cl;
2227 ShenandoahHeap* _heap;
2228 ShenandoahRegionIterator* _regions;
2229 bool _concurrent;
2230 public:
2231 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2232 AbstractGangTask("Concurrent Update References Task"),
2233 cl(T()),
2234 _heap(ShenandoahHeap::heap()),
2235 _regions(regions),
2236 _concurrent(concurrent) {
2237 }
2238
2239 void work(uint worker_id) {
2240 if (_concurrent) {
2241 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2242 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2243 do_work();
2244 } else {
2245 ShenandoahParallelWorkerSession worker_session(worker_id);
2246 do_work();
2247 }
2248 }
2249
2250 private:
2251 void do_work() {
2252 ShenandoahHeapRegion* r = _regions->next();
2253 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2254 while (r != NULL) {
2255 HeapWord* top_at_start_ur = r->concurrent_iteration_safe_limit();
2256 assert (top_at_start_ur >= r->bottom(), "sanity");
2257 if (r->is_active() && !r->is_cset()) {
2258 _heap->marked_object_oop_iterate(r, &cl, top_at_start_ur);
2259 }
2260 if (ShenandoahPacing) {
2261 _heap->pacer()->report_updaterefs(pointer_delta(top_at_start_ur, r->bottom()));
2262 }
2263 if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
2264 return;
2265 }
2266 r = _regions->next();
2267 }
2268 }
2269 };
2270
2271 void ShenandoahHeap::update_heap_references(bool concurrent) {
2272 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
2273 workers()->run_task(&task);
2274 }
2275
2276 void ShenandoahHeap::op_init_updaterefs() {
2277 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2278
2279 set_evacuation_in_progress(false);
2280
2281 {
2282 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_retire_gclabs);
2283 retire_and_reset_gclabs();
2284 }
2285
2286 if (ShenandoahVerify) {
2287 if (!is_degenerated_gc_in_progress()) {
2288 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots);
2289 }
2290 verifier()->verify_before_updaterefs();
2291 }
2292
2293 set_update_refs_in_progress(true);
2294
2295 {
2296 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_prepare);
2297
2298 make_parsable(true);
2299 for (uint i = 0; i < num_regions(); i++) {
2300 ShenandoahHeapRegion* r = get_region(i);
2301 r->set_concurrent_iteration_safe_limit(r->top());
2302 }
2303
2304 // Reset iterator.
2305 _update_refs_iterator.reset();
2306 }
2307
2308 if (ShenandoahPacing) {
2309 pacer()->setup_for_updaterefs();
2310 }
2311 }
2312
2313 void ShenandoahHeap::op_final_updaterefs() {
2314 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2315
2316 // Check if there is left-over work, and finish it
2317 if (_update_refs_iterator.has_next()) {
2318 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2319
2320 // Finish updating references where we left off.
2321 clear_cancelled_gc();
2322 update_heap_references(false);
2323 }
2324
2325 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2326 // everything. On degenerated paths, cancelled gc would not be set anyway.
2327 if (cancelled_gc()) {
2328 clear_cancelled_gc();
2329 }
2330 assert(!cancelled_gc(), "Should have been done right before");
2331
2332 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2333 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots);
2334 }
2335
2336 if (is_degenerated_gc_in_progress()) {
2337 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2338 } else {
2339 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2340 }
2341
2342 // Has to be done before cset is clear
2343 if (ShenandoahVerify) {
2344 verifier()->verify_roots_in_to_space();
2345 }
2346
2347 // Drop unnecessary "pinned" state from regions that does not have CP marks
2348 // anymore, as this would allow trashing them below.
2349 {
2350 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_sync_pinned);
2351 sync_pinned_region_status();
2352 }
2353
2354 {
2355 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2356 trash_cset_regions();
2357 }
2358
2359 set_has_forwarded_objects(false);
2360 set_update_refs_in_progress(false);
2361
2362 if (ShenandoahVerify) {
2363 verifier()->verify_after_updaterefs();
2364 }
2365
2366 if (VerifyAfterGC) {
2367 Universe::verify();
2368 }
2369
2370 {
2371 ShenandoahHeapLocker locker(lock());
2372 _free_set->rebuild();
2373 }
2374 }
2375
2376 #ifdef ASSERT
2377 void ShenandoahHeap::assert_heaplock_owned_by_current_thread() {
2378 _lock.assert_owned_by_current_thread();
2379 }
2380
2381 void ShenandoahHeap::assert_heaplock_not_owned_by_current_thread() {
2382 _lock.assert_not_owned_by_current_thread();
2383 }
2384
2385 void ShenandoahHeap::assert_heaplock_or_safepoint() {
2386 _lock.assert_owned_by_current_thread_or_safepoint();
2387 }
2388 #endif
2389
2390 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2391 print_on(st);
2392 print_heap_regions_on(st);
2393 }
2394
2395 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2396 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2397
2398 size_t regions_from = _bitmap_regions_per_slice * slice;
2399 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2400 for (size_t g = regions_from; g < regions_to; g++) {
2401 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2402 if (skip_self && g == r->region_number()) continue;
2403 if (get_region(g)->is_committed()) {
2404 return true;
2405 }
2406 }
2407 return false;
2408 }
2409
2410 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2411 assert_heaplock_owned_by_current_thread();
2412
2413 // Bitmaps in special regions do not need commits
2414 if (_bitmap_region_special) {
2415 return true;
2416 }
2417
2418 if (is_bitmap_slice_committed(r, true)) {
2419 // Some other region from the group is already committed, meaning the bitmap
2420 // slice is already committed, we exit right away.
2421 return true;
2422 }
2423
2424 // Commit the bitmap slice:
2425 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2426 size_t off = _bitmap_bytes_per_slice * slice;
2427 size_t len = _bitmap_bytes_per_slice;
2428 if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) {
2429 return false;
2430 }
2431 return true;
2432 }
2433
2434 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2435 assert_heaplock_owned_by_current_thread();
2436
2437 // Bitmaps in special regions do not need uncommits
2438 if (_bitmap_region_special) {
2439 return true;
2440 }
2441
2442 if (is_bitmap_slice_committed(r, true)) {
2443 // Some other region from the group is still committed, meaning the bitmap
2444 // slice is should stay committed, exit right away.
2445 return true;
2446 }
2447
2448 // Uncommit the bitmap slice:
2449 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2450 size_t off = _bitmap_bytes_per_slice * slice;
2451 size_t len = _bitmap_bytes_per_slice;
2452 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2453 return false;
2454 }
2455 return true;
2456 }
2457
2458 void ShenandoahHeap::safepoint_synchronize_begin() {
2459 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2460 SuspendibleThreadSet::synchronize();
2461 }
2462 }
2463
2464 void ShenandoahHeap::safepoint_synchronize_end() {
2465 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2466 SuspendibleThreadSet::desynchronize();
2467 }
2468 }
2469
2470 void ShenandoahHeap::vmop_entry_init_mark() {
2471 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2472 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2473 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
2474
2475 try_inject_alloc_failure();
2476 VM_ShenandoahInitMark op;
2477 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2478 }
2479
2480 void ShenandoahHeap::vmop_entry_final_mark() {
2481 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2482 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2483 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
2484
2485 try_inject_alloc_failure();
2486 VM_ShenandoahFinalMarkStartEvac op;
2487 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2488 }
2489
2490 void ShenandoahHeap::vmop_entry_final_evac() {
2491 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2492 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2493 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_gross);
2494
2495 VM_ShenandoahFinalEvac op;
2496 VMThread::execute(&op); // jump to entry_final_evac under safepoint
2497 }
2498
2499 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2500 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2501 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2502 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
2503
2504 try_inject_alloc_failure();
2505 VM_ShenandoahInitUpdateRefs op;
2506 VMThread::execute(&op);
2507 }
2508
2509 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2510 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2511 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2512 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
2513
2514 try_inject_alloc_failure();
2515 VM_ShenandoahFinalUpdateRefs op;
2516 VMThread::execute(&op);
2517 }
2518
2519 void ShenandoahHeap::vmop_entry_init_traversal() {
2520 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2521 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2522 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc_gross);
2523
2524 try_inject_alloc_failure();
2525 VM_ShenandoahInitTraversalGC op;
2526 VMThread::execute(&op);
2527 }
2528
2529 void ShenandoahHeap::vmop_entry_final_traversal() {
2530 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2531 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2532 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc_gross);
2533
2534 try_inject_alloc_failure();
2535 VM_ShenandoahFinalTraversalGC op;
2536 VMThread::execute(&op);
2537 }
2538
2539 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2540 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2541 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2542 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
2543
2544 try_inject_alloc_failure();
2545 VM_ShenandoahFullGC op(cause);
2546 VMThread::execute(&op);
2547 }
2548
2549 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2550 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2551 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2552 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
2553
2554 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2555 VMThread::execute(°enerated_gc);
2556 }
2557
2558 void ShenandoahHeap::entry_init_mark() {
2559 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2560 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
2561 const char* msg = init_mark_event_message();
2562 GCTraceTime(Info, gc) time(msg, gc_timer());
2563 EventMark em("%s", msg);
2564
2565 ShenandoahWorkerScope scope(workers(),
2566 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2567 "init marking");
2568
2569 op_init_mark();
2570 }
2571
2572 void ShenandoahHeap::entry_final_mark() {
2573 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2574 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
2575 const char* msg = final_mark_event_message();
2576 GCTraceTime(Info, gc) time(msg, gc_timer());
2577 EventMark em("%s", msg);
2578
2579 ShenandoahWorkerScope scope(workers(),
2580 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2581 "final marking");
2582
2583 op_final_mark();
2584 }
2585
2586 void ShenandoahHeap::entry_final_evac() {
2587 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2588 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac);
2589 static const char* msg = "Pause Final Evac";
2590 GCTraceTime(Info, gc) time(msg, gc_timer());
2591 EventMark em("%s", msg);
2592
2593 op_final_evac();
2594 }
2595
2596 void ShenandoahHeap::entry_init_updaterefs() {
2597 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2598 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
2599
2600 static const char* msg = "Pause Init Update Refs";
2601 GCTraceTime(Info, gc) time(msg, gc_timer());
2602 EventMark em("%s", msg);
2603
2604 // No workers used in this phase, no setup required
2605
2606 op_init_updaterefs();
2607 }
2608
2609 void ShenandoahHeap::entry_final_updaterefs() {
2610 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2611 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
2612
2613 static const char* msg = "Pause Final Update Refs";
2614 GCTraceTime(Info, gc) time(msg, gc_timer());
2615 EventMark em("%s", msg);
2616
2617 ShenandoahWorkerScope scope(workers(),
2618 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2619 "final reference update");
2620
2621 op_final_updaterefs();
2622 }
2623
2624 void ShenandoahHeap::entry_init_traversal() {
2625 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2626 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc);
2627
2628 static const char* msg = "Pause Init Traversal";
2629 GCTraceTime(Info, gc) time(msg, gc_timer());
2630 EventMark em("%s", msg);
2631
2632 ShenandoahWorkerScope scope(workers(),
2633 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2634 "init traversal");
2635
2636 op_init_traversal();
2637 }
2638
2639 void ShenandoahHeap::entry_final_traversal() {
2640 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2641 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc);
2642
2643 static const char* msg = "Pause Final Traversal";
2644 GCTraceTime(Info, gc) time(msg, gc_timer());
2645 EventMark em("%s", msg);
2646
2647 ShenandoahWorkerScope scope(workers(),
2648 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2649 "final traversal");
2650
2651 op_final_traversal();
2652 }
2653
2654 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2655 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2656 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
2657
2658 static const char* msg = "Pause Full";
2659 GCTraceTime(Info, gc) time(msg, gc_timer(), cause, true);
2660 EventMark em("%s", msg);
2661
2662 ShenandoahWorkerScope scope(workers(),
2663 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2664 "full gc");
2665
2666 op_full(cause);
2667 }
2668
2669 void ShenandoahHeap::entry_degenerated(int point) {
2670 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2671 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
2672
2673 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2674 const char* msg = degen_event_message(dpoint);
2675 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2676 EventMark em("%s", msg);
2677
2678 ShenandoahWorkerScope scope(workers(),
2679 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2680 "stw degenerated gc");
2681
2682 set_degenerated_gc_in_progress(true);
2683 op_degenerated(dpoint);
2684 set_degenerated_gc_in_progress(false);
2685 }
2686
2687 void ShenandoahHeap::entry_mark() {
2688 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2689
2690 const char* msg = conc_mark_event_message();
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_conc_marking(),
2696 "concurrent marking");
2697
2698 try_inject_alloc_failure();
2699 op_mark();
2700 }
2701
2702 void ShenandoahHeap::entry_evac() {
2703 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
2704 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2705
2706 static const char* msg = "Concurrent evacuation";
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_evac(),
2712 "concurrent evacuation");
2713
2714 try_inject_alloc_failure();
2715 op_conc_evac();
2716 }
2717
2718 void ShenandoahHeap::entry_updaterefs() {
2719 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
2720
2721 static const char* msg = "Concurrent update references";
2722 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2723 EventMark em("%s", msg);
2724
2725 ShenandoahWorkerScope scope(workers(),
2726 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2727 "concurrent reference update");
2728
2729 try_inject_alloc_failure();
2730 op_updaterefs();
2731 }
2732
2733 void ShenandoahHeap::entry_roots() {
2734 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_roots);
2735
2736 static const char* msg = "Concurrent roots processing";
2737 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2738 EventMark em("%s", msg);
2739
2740 ShenandoahWorkerScope scope(workers(),
2741 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2742 "concurrent root processing");
2743
2744 try_inject_alloc_failure();
2745 op_roots();
2746 }
2747
2748 void ShenandoahHeap::entry_cleanup() {
2749 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup);
2750
2751 static const char* msg = "Concurrent cleanup";
2752 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2753 EventMark em("%s", msg);
2754
2755 // This phase does not use workers, no need for setup
2756
2757 try_inject_alloc_failure();
2758 op_cleanup();
2759 }
2760
2761 void ShenandoahHeap::entry_reset() {
2762 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset);
2763
2764 static const char* msg = "Concurrent reset";
2765 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2766 EventMark em("%s", msg);
2767
2768 ShenandoahWorkerScope scope(workers(),
2769 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2770 "concurrent reset");
2771
2772 try_inject_alloc_failure();
2773 op_reset();
2774 }
2775
2776 void ShenandoahHeap::entry_preclean() {
2777 if (ShenandoahPreclean && process_references()) {
2778 static const char* msg = "Concurrent precleaning";
2779 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2780 EventMark em("%s", msg);
2781
2782 ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
2783
2784 ShenandoahWorkerScope scope(workers(),
2785 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2786 "concurrent preclean",
2787 /* check_workers = */ false);
2788
2789 try_inject_alloc_failure();
2790 op_preclean();
2791 }
2792 }
2793
2794 void ShenandoahHeap::entry_traversal() {
2795 static const char* msg = "Concurrent traversal";
2796 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2797 EventMark em("%s", msg);
2798
2799 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2800
2801 ShenandoahWorkerScope scope(workers(),
2802 ShenandoahWorkerPolicy::calc_workers_for_conc_traversal(),
2803 "concurrent traversal");
2804
2805 try_inject_alloc_failure();
2806 op_traversal();
2807 }
2808
2809 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2810 static const char *msg = "Concurrent uncommit";
2811 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2812 EventMark em("%s", msg);
2813
2814 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit);
2815
2816 op_uncommit(shrink_before);
2817 }
2818
2819 void ShenandoahHeap::try_inject_alloc_failure() {
2820 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2821 _inject_alloc_failure.set();
2822 os::naked_short_sleep(1);
2823 if (cancelled_gc()) {
2824 log_info(gc)("Allocation failure was successfully injected");
2825 }
2826 }
2827 }
2828
2829 bool ShenandoahHeap::should_inject_alloc_failure() {
2830 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2831 }
2832
2833 void ShenandoahHeap::initialize_serviceability() {
2834 _memory_pool = new ShenandoahMemoryPool(this);
2835 _cycle_memory_manager.add_pool(_memory_pool);
2836 _stw_memory_manager.add_pool(_memory_pool);
2837 }
2838
2839 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2840 GrowableArray<GCMemoryManager*> memory_managers(2);
2841 memory_managers.append(&_cycle_memory_manager);
2842 memory_managers.append(&_stw_memory_manager);
2843 return memory_managers;
2844 }
2845
2846 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2847 GrowableArray<MemoryPool*> memory_pools(1);
2848 memory_pools.append(_memory_pool);
2849 return memory_pools;
2850 }
2851
2852 MemoryUsage ShenandoahHeap::memory_usage() {
2853 return _memory_pool->get_memory_usage();
2854 }
2855
2856 void ShenandoahHeap::enter_evacuation() {
2857 _oom_evac_handler.enter_evacuation();
2858 }
2859
2860 void ShenandoahHeap::leave_evacuation() {
2861 _oom_evac_handler.leave_evacuation();
2862 }
2863
2864 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2865 _heap(ShenandoahHeap::heap()),
2866 _index(0) {}
2867
2868 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2869 _heap(heap),
2870 _index(0) {}
2871
2872 void ShenandoahRegionIterator::reset() {
2873 _index = 0;
2874 }
2875
2876 bool ShenandoahRegionIterator::has_next() const {
2877 return _index < _heap->num_regions();
2878 }
2879
2880 char ShenandoahHeap::gc_state() const {
2881 return _gc_state.raw_value();
2882 }
2883
2884 void ShenandoahHeap::deduplicate_string(oop str) {
2885 assert(java_lang_String::is_instance(str), "invariant");
2886
2887 if (ShenandoahStringDedup::is_enabled()) {
2888 ShenandoahStringDedup::deduplicate(str);
2889 }
2890 }
2891
2892 const char* ShenandoahHeap::init_mark_event_message() const {
2893 bool update_refs = has_forwarded_objects();
2894 bool proc_refs = process_references();
2895 bool unload_cls = unload_classes();
2896
2897 if (update_refs && proc_refs && unload_cls) {
2898 return "Pause Init Mark (update refs) (process weakrefs) (unload classes)";
2899 } else if (update_refs && proc_refs) {
2900 return "Pause Init Mark (update refs) (process weakrefs)";
2901 } else if (update_refs && unload_cls) {
2902 return "Pause Init Mark (update refs) (unload classes)";
2903 } else if (proc_refs && unload_cls) {
2904 return "Pause Init Mark (process weakrefs) (unload classes)";
2905 } else if (update_refs) {
2906 return "Pause Init Mark (update refs)";
2907 } else if (proc_refs) {
2908 return "Pause Init Mark (process weakrefs)";
2909 } else if (unload_cls) {
2910 return "Pause Init Mark (unload classes)";
2911 } else {
2912 return "Pause Init Mark";
2913 }
2914 }
2915
2916 const char* ShenandoahHeap::final_mark_event_message() const {
2917 bool update_refs = has_forwarded_objects();
2918 bool proc_refs = process_references();
2919 bool unload_cls = unload_classes();
2920
2921 if (update_refs && proc_refs && unload_cls) {
2922 return "Pause Final Mark (update refs) (process weakrefs) (unload classes)";
2923 } else if (update_refs && proc_refs) {
2924 return "Pause Final Mark (update refs) (process weakrefs)";
2925 } else if (update_refs && unload_cls) {
2926 return "Pause Final Mark (update refs) (unload classes)";
2927 } else if (proc_refs && unload_cls) {
2928 return "Pause Final Mark (process weakrefs) (unload classes)";
2929 } else if (update_refs) {
2930 return "Pause Final Mark (update refs)";
2931 } else if (proc_refs) {
2932 return "Pause Final Mark (process weakrefs)";
2933 } else if (unload_cls) {
2934 return "Pause Final Mark (unload classes)";
2935 } else {
2936 return "Pause Final Mark";
2937 }
2938 }
2939
2940 const char* ShenandoahHeap::conc_mark_event_message() const {
2941 bool update_refs = has_forwarded_objects();
2942 bool proc_refs = process_references();
2943 bool unload_cls = unload_classes();
2944
2945 if (update_refs && proc_refs && unload_cls) {
2946 return "Concurrent marking (update refs) (process weakrefs) (unload classes)";
2947 } else if (update_refs && proc_refs) {
2948 return "Concurrent marking (update refs) (process weakrefs)";
2949 } else if (update_refs && unload_cls) {
2950 return "Concurrent marking (update refs) (unload classes)";
2951 } else if (proc_refs && unload_cls) {
2952 return "Concurrent marking (process weakrefs) (unload classes)";
2953 } else if (update_refs) {
2954 return "Concurrent marking (update refs)";
2955 } else if (proc_refs) {
2956 return "Concurrent marking (process weakrefs)";
2957 } else if (unload_cls) {
2958 return "Concurrent marking (unload classes)";
2959 } else {
2960 return "Concurrent marking";
2961 }
2962 }
2963
2964 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
2965 switch (point) {
2966 case _degenerated_unset:
2967 return "Pause Degenerated GC (<UNSET>)";
2968 case _degenerated_traversal:
2969 return "Pause Degenerated GC (Traversal)";
2970 case _degenerated_outside_cycle:
2971 return "Pause Degenerated GC (Outside of Cycle)";
2972 case _degenerated_mark:
2973 return "Pause Degenerated GC (Mark)";
2974 case _degenerated_evac:
2975 return "Pause Degenerated GC (Evacuation)";
2976 case _degenerated_updaterefs:
2977 return "Pause Degenerated GC (Update Refs)";
2978 default:
2979 ShouldNotReachHere();
2980 return "ERROR";
2981 }
2982 }
2983
2984 jushort* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2985 #ifdef ASSERT
2986 assert(_liveness_cache != NULL, "sanity");
2987 assert(worker_id < _max_workers, "sanity");
2988 for (uint i = 0; i < num_regions(); i++) {
2989 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2990 }
2991 #endif
2992 return _liveness_cache[worker_id];
2993 }
2994
2995 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2996 assert(worker_id < _max_workers, "sanity");
2997 assert(_liveness_cache != NULL, "sanity");
2998 jushort* ld = _liveness_cache[worker_id];
2999 for (uint i = 0; i < num_regions(); i++) {
3000 ShenandoahHeapRegion* r = get_region(i);
3001 jushort live = ld[i];
3002 if (live > 0) {
3003 r->increase_live_data_gc_words(live);
3004 ld[i] = 0;
3005 }
3006 }
3007 }