1 /*
2 * Copyright (c) 2013, 2019, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #include "precompiled.hpp"
25 #include "memory/allocation.hpp"
26 #include "memory/universe.hpp"
27
28 #include "gc/shared/gcArguments.hpp"
29 #include "gc/shared/gcTimer.hpp"
30 #include "gc/shared/gcTraceTime.inline.hpp"
31 #include "gc/shared/locationPrinter.inline.hpp"
32 #include "gc/shared/memAllocator.hpp"
33 #include "gc/shared/plab.hpp"
34
35 #include "gc/shenandoah/shenandoahAllocTracker.hpp"
36 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
37 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
38 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
39 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
40 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
41 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
42 #include "gc/shenandoah/shenandoahControlThread.hpp"
43 #include "gc/shenandoah/shenandoahFreeSet.hpp"
44 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
45 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
46 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
47 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
48 #include "gc/shenandoah/shenandoahMarkCompact.hpp"
49 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
50 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
51 #include "gc/shenandoah/shenandoahMetrics.hpp"
52 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
53 #include "gc/shenandoah/shenandoahNormalMode.hpp"
54 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
55 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
56 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
57 #include "gc/shenandoah/shenandoahPassiveMode.hpp"
58 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
59 #include "gc/shenandoah/shenandoahStringDedup.hpp"
60 #include "gc/shenandoah/shenandoahTaskqueue.hpp"
61 #include "gc/shenandoah/shenandoahTraversalMode.hpp"
62 #include "gc/shenandoah/shenandoahUtils.hpp"
63 #include "gc/shenandoah/shenandoahVerifier.hpp"
64 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
65 #include "gc/shenandoah/shenandoahVMOperations.hpp"
66 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
67 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
68 #if INCLUDE_JFR
69 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
70 #endif
71
72 #include "memory/metaspace.hpp"
73 #include "oops/compressedOops.inline.hpp"
74 #include "runtime/atomic.hpp"
75 #include "runtime/globals.hpp"
76 #include "runtime/interfaceSupport.inline.hpp"
77 #include "runtime/orderAccess.hpp"
78 #include "runtime/safepointMechanism.hpp"
79 #include "runtime/vmThread.hpp"
80 #include "services/mallocTracker.hpp"
81
82 #ifdef ASSERT
83 template <class T>
84 void ShenandoahAssertToSpaceClosure::do_oop_work(T* p) {
85 T o = RawAccess<>::oop_load(p);
86 if (! CompressedOops::is_null(o)) {
87 oop obj = CompressedOops::decode_not_null(o);
88 shenandoah_assert_not_forwarded(p, obj);
89 }
90 }
91
92 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_work(p); }
93 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_work(p); }
94 #endif
95
96 class ShenandoahPretouchHeapTask : public AbstractGangTask {
97 private:
98 ShenandoahRegionIterator _regions;
99 const size_t _page_size;
100 public:
101 ShenandoahPretouchHeapTask(size_t page_size) :
102 AbstractGangTask("Shenandoah Pretouch Heap"),
103 _page_size(page_size) {}
104
105 virtual void work(uint worker_id) {
106 ShenandoahHeapRegion* r = _regions.next();
107 while (r != NULL) {
108 os::pretouch_memory(r->bottom(), r->end(), _page_size);
109 r = _regions.next();
110 }
111 }
112 };
113
114 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
115 private:
116 ShenandoahRegionIterator _regions;
117 char* _bitmap_base;
118 const size_t _bitmap_size;
119 const size_t _page_size;
120 public:
121 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
122 AbstractGangTask("Shenandoah Pretouch Bitmap"),
123 _bitmap_base(bitmap_base),
124 _bitmap_size(bitmap_size),
125 _page_size(page_size) {}
126
127 virtual void work(uint worker_id) {
128 ShenandoahHeapRegion* r = _regions.next();
129 while (r != NULL) {
130 size_t start = r->region_number() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
131 size_t end = (r->region_number() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
132 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
133
134 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
135
136 r = _regions.next();
137 }
138 }
139 };
140
141 jint ShenandoahHeap::initialize() {
142 initialize_heuristics();
143
144 //
145 // Figure out heap sizing
146 //
147
148 size_t init_byte_size = InitialHeapSize;
149 size_t min_byte_size = MinHeapSize;
150 size_t max_byte_size = MaxHeapSize;
151 size_t heap_alignment = HeapAlignment;
152
153 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
154
155 if (ShenandoahAlwaysPreTouch) {
156 // Enabled pre-touch means the entire heap is committed right away.
157 init_byte_size = max_byte_size;
158 }
159
160 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
161 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
162
163 _num_regions = ShenandoahHeapRegion::region_count();
164
165 size_t num_committed_regions = init_byte_size / reg_size_bytes;
166 num_committed_regions = MIN2(num_committed_regions, _num_regions);
167 assert(num_committed_regions <= _num_regions, "sanity");
168 _initial_size = num_committed_regions * reg_size_bytes;
169
170 size_t num_min_regions = min_byte_size / reg_size_bytes;
171 num_min_regions = MIN2(num_min_regions, _num_regions);
172 assert(num_min_regions <= _num_regions, "sanity");
173 _minimum_size = num_min_regions * reg_size_bytes;
174
175 _committed = _initial_size;
176
177 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
178 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
179
180 //
181 // Reserve and commit memory for heap
182 //
183
184 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
185 initialize_reserved_region(heap_rs);
186 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
187 _heap_region_special = heap_rs.special();
188
189 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
190 "Misaligned heap: " PTR_FORMAT, p2i(base()));
191
192 #if SHENANDOAH_OPTIMIZED_OBJTASK
193 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
194 // Fail if we ever attempt to address more than we can.
195 if ((uintptr_t)heap_rs.end() >= ObjArrayChunkedTask::max_addressable()) {
196 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
197 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
198 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
199 p2i(heap_rs.base()), p2i(heap_rs.end()), ObjArrayChunkedTask::max_addressable());
200 vm_exit_during_initialization("Fatal Error", buf);
201 }
202 #endif
203
204 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
205 if (!_heap_region_special) {
206 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
207 "Cannot commit heap memory");
208 }
209
210 //
211 // Reserve and commit memory for bitmap(s)
212 //
213
214 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
215 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
216
217 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
218
219 guarantee(bitmap_bytes_per_region != 0,
220 "Bitmap bytes per region should not be zero");
221 guarantee(is_power_of_2(bitmap_bytes_per_region),
222 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
223
224 if (bitmap_page_size > bitmap_bytes_per_region) {
225 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
226 _bitmap_bytes_per_slice = bitmap_page_size;
227 } else {
228 _bitmap_regions_per_slice = 1;
229 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
230 }
231
232 guarantee(_bitmap_regions_per_slice >= 1,
233 "Should have at least one region per slice: " SIZE_FORMAT,
234 _bitmap_regions_per_slice);
235
236 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
237 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
238 _bitmap_bytes_per_slice, bitmap_page_size);
239
240 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
241 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
242 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
243 _bitmap_region_special = bitmap.special();
244
245 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
246 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
247 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
248 if (!_bitmap_region_special) {
249 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
250 "Cannot commit bitmap memory");
251 }
252
253 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
254
255 if (ShenandoahVerify) {
256 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
257 if (!verify_bitmap.special()) {
258 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
259 "Cannot commit verification bitmap memory");
260 }
261 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
262 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
263 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
264 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
265 }
266
267 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
268 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
269 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
270 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
271 _aux_bitmap_region_special = aux_bitmap.special();
272 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
273
274 //
275 // Create regions and region sets
276 //
277
278 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
279 _free_set = new ShenandoahFreeSet(this, _num_regions);
280 _collection_set = new ShenandoahCollectionSet(this, sh_rs.base(), sh_rs.size());
281
282 {
283 ShenandoahHeapLocker locker(lock());
284
285 size_t size_words = ShenandoahHeapRegion::region_size_words();
286
287 for (size_t i = 0; i < _num_regions; i++) {
288 HeapWord* start = (HeapWord*)sh_rs.base() + size_words * i;
289 bool is_committed = i < num_committed_regions;
290 ShenandoahHeapRegion* r = new ShenandoahHeapRegion(this, start, size_words, i, is_committed);
291
292 _marking_context->initialize_top_at_mark_start(r);
293 _regions[i] = r;
294 assert(!collection_set()->is_in(i), "New region should not be in collection set");
295 }
296
297 // Initialize to complete
298 _marking_context->mark_complete();
299
300 _free_set->rebuild();
301 }
302
303 if (ShenandoahAlwaysPreTouch) {
304 assert(!AlwaysPreTouch, "Should have been overridden");
305
306 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
307 // before initialize() below zeroes it with initializing thread. For any given region,
308 // we touch the region and the corresponding bitmaps from the same thread.
309 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
310
311 size_t pretouch_heap_page_size = heap_page_size;
312 size_t pretouch_bitmap_page_size = bitmap_page_size;
313
314 #ifdef LINUX
315 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
316 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
317 // them into huge one. Therefore, we need to pretouch with smaller pages.
318 if (UseTransparentHugePages) {
319 pretouch_heap_page_size = (size_t)os::vm_page_size();
320 pretouch_bitmap_page_size = (size_t)os::vm_page_size();
321 }
322 #endif
323
324 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
325 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
326
327 log_info(gc, init)("Pretouch bitmap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
328 _num_regions, pretouch_bitmap_page_size);
329 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, pretouch_bitmap_page_size);
330 _workers->run_task(&bcl);
331
332 log_info(gc, init)("Pretouch heap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
333 _num_regions, pretouch_heap_page_size);
334 ShenandoahPretouchHeapTask hcl(pretouch_heap_page_size);
335 _workers->run_task(&hcl);
336 }
337
338 //
339 // Initialize the rest of GC subsystems
340 //
341
342 _liveness_cache = NEW_C_HEAP_ARRAY(jushort*, _max_workers, mtGC);
343 for (uint worker = 0; worker < _max_workers; worker++) {
344 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(jushort, _num_regions, mtGC);
345 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(jushort));
346 }
347
348 // There should probably be Shenandoah-specific options for these,
349 // just as there are G1-specific options.
350 {
351 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
352 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
353 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
354 }
355
356 _monitoring_support = new ShenandoahMonitoringSupport(this);
357 _phase_timings = new ShenandoahPhaseTimings();
358 ShenandoahStringDedup::initialize();
359 ShenandoahCodeRoots::initialize();
360
361 if (ShenandoahAllocationTrace) {
362 _alloc_tracker = new ShenandoahAllocTracker();
363 }
364
365 if (ShenandoahPacing) {
366 _pacer = new ShenandoahPacer(this);
367 _pacer->setup_for_idle();
368 } else {
369 _pacer = NULL;
370 }
371
372 _traversal_gc = strcmp(ShenandoahGCMode, "traversal") == 0 ?
373 new ShenandoahTraversalGC(this, _num_regions) :
374 NULL;
375
376 _control_thread = new ShenandoahControlThread();
377
378 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max",
379 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size),
380 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size),
381 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity())
382 );
383
384 log_info(gc, init)("Safepointing mechanism: %s",
385 SafepointMechanism::uses_thread_local_poll() ? "thread-local poll" :
386 (SafepointMechanism::uses_global_page_poll() ? "global-page poll" : "unknown"));
387
388 return JNI_OK;
389 }
390
391 void ShenandoahHeap::initialize_heuristics() {
392 if (ShenandoahGCMode != NULL) {
393 if (strcmp(ShenandoahGCMode, "traversal") == 0) {
394 _gc_mode = new ShenandoahTraversalMode();
395 } else if (strcmp(ShenandoahGCMode, "normal") == 0) {
396 _gc_mode = new ShenandoahNormalMode();
397 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
398 _gc_mode = new ShenandoahPassiveMode();
399 } else {
400 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
401 }
402 } else {
403 ShouldNotReachHere();
404 }
405 _gc_mode->initialize_flags();
406 _heuristics = _gc_mode->initialize_heuristics();
407
408 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
409 vm_exit_during_initialization(
410 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
411 _heuristics->name()));
412 }
413 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
414 vm_exit_during_initialization(
415 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
416 _heuristics->name()));
417 }
418 log_info(gc, init)("Shenandoah heuristics: %s",
419 _heuristics->name());
420 }
421
422 #ifdef _MSC_VER
423 #pragma warning( push )
424 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
425 #endif
426
427 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
428 CollectedHeap(),
429 _initial_size(0),
430 _used(0),
431 _committed(0),
432 _bytes_allocated_since_gc_start(0),
433 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
434 _workers(NULL),
435 _safepoint_workers(NULL),
436 _heap_region_special(false),
437 _num_regions(0),
438 _regions(NULL),
439 _update_refs_iterator(this),
440 _control_thread(NULL),
441 _shenandoah_policy(policy),
442 _heuristics(NULL),
443 _free_set(NULL),
444 _scm(new ShenandoahConcurrentMark()),
445 _traversal_gc(NULL),
446 _full_gc(new ShenandoahMarkCompact()),
447 _pacer(NULL),
448 _verifier(NULL),
449 _alloc_tracker(NULL),
450 _phase_timings(NULL),
451 _monitoring_support(NULL),
452 _memory_pool(NULL),
453 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
454 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
455 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
456 _soft_ref_policy(),
457 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
458 _ref_processor(NULL),
459 _marking_context(NULL),
460 _bitmap_size(0),
461 _bitmap_regions_per_slice(0),
462 _bitmap_bytes_per_slice(0),
463 _bitmap_region_special(false),
464 _aux_bitmap_region_special(false),
465 _liveness_cache(NULL),
466 _collection_set(NULL)
467 {
468 log_info(gc, init)("GC threads: " UINT32_FORMAT " parallel, " UINT32_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
469 log_info(gc, init)("Reference processing: %s", ParallelRefProcEnabled ? "parallel" : "serial");
470
471 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
472
473 _max_workers = MAX2(_max_workers, 1U);
474 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
475 /* are_GC_task_threads */ true,
476 /* are_ConcurrentGC_threads */ true);
477 if (_workers == NULL) {
478 vm_exit_during_initialization("Failed necessary allocation.");
479 } else {
480 _workers->initialize_workers();
481 }
482
483 if (ShenandoahParallelSafepointThreads > 1) {
484 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
485 ShenandoahParallelSafepointThreads,
486 /* are_GC_task_threads */ false,
487 /* are_ConcurrentGC_threads */ false);
488 _safepoint_workers->initialize_workers();
489 }
490 }
491
492 #ifdef _MSC_VER
493 #pragma warning( pop )
494 #endif
495
496 class ShenandoahResetBitmapTask : public AbstractGangTask {
497 private:
498 ShenandoahRegionIterator _regions;
499
500 public:
501 ShenandoahResetBitmapTask() :
502 AbstractGangTask("Parallel Reset Bitmap Task") {}
503
504 void work(uint worker_id) {
505 ShenandoahHeapRegion* region = _regions.next();
506 ShenandoahHeap* heap = ShenandoahHeap::heap();
507 ShenandoahMarkingContext* const ctx = heap->marking_context();
508 while (region != NULL) {
509 if (heap->is_bitmap_slice_committed(region)) {
510 ctx->clear_bitmap(region);
511 }
512 region = _regions.next();
513 }
514 }
515 };
516
517 void ShenandoahHeap::reset_mark_bitmap() {
518 assert_gc_workers(_workers->active_workers());
519 mark_incomplete_marking_context();
520
521 ShenandoahResetBitmapTask task;
522 _workers->run_task(&task);
523 }
524
525 void ShenandoahHeap::print_on(outputStream* st) const {
526 st->print_cr("Shenandoah Heap");
527 st->print_cr(" " SIZE_FORMAT "%s total, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
528 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
529 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
530 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
531 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
532 num_regions(),
533 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
534 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
535
536 st->print("Status: ");
537 if (has_forwarded_objects()) st->print("has forwarded objects, ");
538 if (is_concurrent_mark_in_progress()) st->print("marking, ");
539 if (is_evacuation_in_progress()) st->print("evacuating, ");
540 if (is_update_refs_in_progress()) st->print("updating refs, ");
541 if (is_concurrent_traversal_in_progress()) st->print("traversal, ");
542 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
543 if (is_full_gc_in_progress()) st->print("full gc, ");
544 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
545 if (is_concurrent_root_in_progress()) st->print("concurrent roots, ");
546
547 if (cancelled_gc()) {
548 st->print("cancelled");
549 } else {
550 st->print("not cancelled");
551 }
552 st->cr();
553
554 st->print_cr("Reserved region:");
555 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
556 p2i(reserved_region().start()),
557 p2i(reserved_region().end()));
558
559 ShenandoahCollectionSet* cset = collection_set();
560 st->print_cr("Collection set:");
561 if (cset != NULL) {
562 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
563 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
564 } else {
565 st->print_cr(" (NULL)");
566 }
567
568 st->cr();
569 MetaspaceUtils::print_on(st);
570
571 if (Verbose) {
572 print_heap_regions_on(st);
573 }
574 }
575
576 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
577 public:
578 void do_thread(Thread* thread) {
579 assert(thread != NULL, "Sanity");
580 assert(thread->is_Worker_thread(), "Only worker thread expected");
581 ShenandoahThreadLocalData::initialize_gclab(thread);
582 }
583 };
584
585 void ShenandoahHeap::post_initialize() {
586 CollectedHeap::post_initialize();
587 MutexLocker ml(Threads_lock);
588
589 ShenandoahInitWorkerGCLABClosure init_gclabs;
590 _workers->threads_do(&init_gclabs);
591
592 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
593 // Now, we will let WorkGang to initialize gclab when new worker is created.
594 _workers->set_initialize_gclab();
595
596 _scm->initialize(_max_workers);
597 _full_gc->initialize(_gc_timer);
598
599 ref_processing_init();
600
601 _heuristics->initialize();
602
603 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
604 }
605
606 size_t ShenandoahHeap::used() const {
607 return Atomic::load_acquire(&_used);
608 }
609
610 size_t ShenandoahHeap::committed() const {
611 OrderAccess::acquire();
612 return _committed;
613 }
614
615 void ShenandoahHeap::increase_committed(size_t bytes) {
616 assert_heaplock_or_safepoint();
617 _committed += bytes;
618 }
619
620 void ShenandoahHeap::decrease_committed(size_t bytes) {
621 assert_heaplock_or_safepoint();
622 _committed -= bytes;
623 }
624
625 void ShenandoahHeap::increase_used(size_t bytes) {
626 Atomic::add(&_used, bytes);
627 }
628
629 void ShenandoahHeap::set_used(size_t bytes) {
630 Atomic::release_store_fence(&_used, bytes);
631 }
632
633 void ShenandoahHeap::decrease_used(size_t bytes) {
634 assert(used() >= bytes, "never decrease heap size by more than we've left");
635 Atomic::sub(&_used, bytes);
636 }
637
638 void ShenandoahHeap::increase_allocated(size_t bytes) {
639 Atomic::add(&_bytes_allocated_since_gc_start, bytes);
640 }
641
642 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
643 size_t bytes = words * HeapWordSize;
644 if (!waste) {
645 increase_used(bytes);
646 }
647 increase_allocated(bytes);
648 if (ShenandoahPacing) {
649 control_thread()->pacing_notify_alloc(words);
650 if (waste) {
651 pacer()->claim_for_alloc(words, true);
652 }
653 }
654 }
655
656 size_t ShenandoahHeap::capacity() const {
657 return committed();
658 }
659
660 size_t ShenandoahHeap::max_capacity() const {
661 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
662 }
663
664 size_t ShenandoahHeap::min_capacity() const {
665 return _minimum_size;
666 }
667
668 size_t ShenandoahHeap::initial_capacity() const {
669 return _initial_size;
670 }
671
672 bool ShenandoahHeap::is_in(const void* p) const {
673 HeapWord* heap_base = (HeapWord*) base();
674 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
675 return p >= heap_base && p < last_region_end;
676 }
677
678 void ShenandoahHeap::op_uncommit(double shrink_before) {
679 assert (ShenandoahUncommit, "should be enabled");
680
681 // Application allocates from the beginning of the heap, and GC allocates at
682 // the end of it. It is more efficient to uncommit from the end, so that applications
683 // could enjoy the near committed regions. GC allocations are much less frequent,
684 // and therefore can accept the committing costs.
685
686 size_t count = 0;
687 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
688 ShenandoahHeapRegion* r = get_region(i - 1);
689 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
690 ShenandoahHeapLocker locker(lock());
691 if (r->is_empty_committed()) {
692 // Do not uncommit below minimal capacity
693 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
694 break;
695 }
696
697 r->make_uncommitted();
698 count++;
699 }
700 }
701 SpinPause(); // allow allocators to take the lock
702 }
703
704 if (count > 0) {
705 control_thread()->notify_heap_changed();
706 }
707 }
708
709 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
710 // New object should fit the GCLAB size
711 size_t min_size = MAX2(size, PLAB::min_size());
712
713 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
714 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
715 new_size = MIN2(new_size, PLAB::max_size());
716 new_size = MAX2(new_size, PLAB::min_size());
717
718 // Record new heuristic value even if we take any shortcut. This captures
719 // the case when moderately-sized objects always take a shortcut. At some point,
720 // heuristics should catch up with them.
721 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
722
723 if (new_size < size) {
724 // New size still does not fit the object. Fall back to shared allocation.
725 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
726 return NULL;
727 }
728
729 // Retire current GCLAB, and allocate a new one.
730 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
731 gclab->retire();
732
733 size_t actual_size = 0;
734 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
735 if (gclab_buf == NULL) {
736 return NULL;
737 }
738
739 assert (size <= actual_size, "allocation should fit");
740
741 if (ZeroTLAB) {
742 // ..and clear it.
743 Copy::zero_to_words(gclab_buf, actual_size);
744 } else {
745 // ...and zap just allocated object.
746 #ifdef ASSERT
747 // Skip mangling the space corresponding to the object header to
748 // ensure that the returned space is not considered parsable by
749 // any concurrent GC thread.
750 size_t hdr_size = oopDesc::header_size();
751 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
752 #endif // ASSERT
753 }
754 gclab->set_buf(gclab_buf, actual_size);
755 return gclab->allocate(size);
756 }
757
758 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
759 size_t requested_size,
760 size_t* actual_size) {
761 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
762 HeapWord* res = allocate_memory(req);
763 if (res != NULL) {
764 *actual_size = req.actual_size();
765 } else {
766 *actual_size = 0;
767 }
768 return res;
769 }
770
771 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
772 size_t word_size,
773 size_t* actual_size) {
774 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
775 HeapWord* res = allocate_memory(req);
776 if (res != NULL) {
777 *actual_size = req.actual_size();
778 } else {
779 *actual_size = 0;
780 }
781 return res;
782 }
783
784 ShenandoahHeap* ShenandoahHeap::heap() {
785 CollectedHeap* heap = Universe::heap();
786 assert(heap != NULL, "Unitialized access to ShenandoahHeap::heap()");
787 assert(heap->kind() == CollectedHeap::Shenandoah, "not a shenandoah heap");
788 return (ShenandoahHeap*) heap;
789 }
790
791 ShenandoahHeap* ShenandoahHeap::heap_no_check() {
792 CollectedHeap* heap = Universe::heap();
793 return (ShenandoahHeap*) heap;
794 }
795
796 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
797 ShenandoahAllocTrace trace_alloc(req.size(), req.type());
798
799 intptr_t pacer_epoch = 0;
800 bool in_new_region = false;
801 HeapWord* result = NULL;
802
803 if (req.is_mutator_alloc()) {
804 if (ShenandoahPacing) {
805 pacer()->pace_for_alloc(req.size());
806 pacer_epoch = pacer()->epoch();
807 }
808
809 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
810 result = allocate_memory_under_lock(req, in_new_region);
811 }
812
813 // Allocation failed, block until control thread reacted, then retry allocation.
814 //
815 // It might happen that one of the threads requesting allocation would unblock
816 // way later after GC happened, only to fail the second allocation, because
817 // other threads have already depleted the free storage. In this case, a better
818 // strategy is to try again, as long as GC makes progress.
819 //
820 // Then, we need to make sure the allocation was retried after at least one
821 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
822
823 size_t tries = 0;
824
825 while (result == NULL && _progress_last_gc.is_set()) {
826 tries++;
827 control_thread()->handle_alloc_failure(req.size());
828 result = allocate_memory_under_lock(req, in_new_region);
829 }
830
831 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
832 tries++;
833 control_thread()->handle_alloc_failure(req.size());
834 result = allocate_memory_under_lock(req, in_new_region);
835 }
836
837 } else {
838 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
839 result = allocate_memory_under_lock(req, in_new_region);
840 // Do not call handle_alloc_failure() here, because we cannot block.
841 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
842 }
843
844 if (in_new_region) {
845 control_thread()->notify_heap_changed();
846 }
847
848 if (result != NULL) {
849 size_t requested = req.size();
850 size_t actual = req.actual_size();
851
852 assert (req.is_lab_alloc() || (requested == actual),
853 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
854 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
855
856 if (req.is_mutator_alloc()) {
857 notify_mutator_alloc_words(actual, false);
858
859 // If we requested more than we were granted, give the rest back to pacer.
860 // This only matters if we are in the same pacing epoch: do not try to unpace
861 // over the budget for the other phase.
862 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
863 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
864 }
865 } else {
866 increase_used(actual*HeapWordSize);
867 }
868 }
869
870 return result;
871 }
872
873 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
874 ShenandoahHeapLocker locker(lock());
875 return _free_set->allocate(req, in_new_region);
876 }
877
878 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
879 bool* gc_overhead_limit_was_exceeded) {
880 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
881 return allocate_memory(req);
882 }
883
884 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
885 size_t size,
886 Metaspace::MetadataType mdtype) {
887 MetaWord* result;
888
889 // Inform metaspace OOM to GC heuristics if class unloading is possible.
890 if (heuristics()->can_unload_classes()) {
891 ShenandoahHeuristics* h = heuristics();
892 h->record_metaspace_oom();
893 }
894
895 // Expand and retry allocation
896 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
897 if (result != NULL) {
898 return result;
899 }
900
901 // Start full GC
902 collect(GCCause::_metadata_GC_clear_soft_refs);
903
904 // Retry allocation
905 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
906 if (result != NULL) {
907 return result;
908 }
909
910 // Expand and retry allocation
911 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
912 if (result != NULL) {
913 return result;
914 }
915
916 // Out of memory
917 return NULL;
918 }
919
920 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
921 private:
922 ShenandoahHeap* const _heap;
923 Thread* const _thread;
924 public:
925 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
926 _heap(heap), _thread(Thread::current()) {}
927
928 void do_object(oop p) {
929 shenandoah_assert_marked(NULL, p);
930 if (!p->is_forwarded()) {
931 _heap->evacuate_object(p, _thread);
932 }
933 }
934 };
935
936 class ShenandoahEvacuationTask : public AbstractGangTask {
937 private:
938 ShenandoahHeap* const _sh;
939 ShenandoahCollectionSet* const _cs;
940 bool _concurrent;
941 public:
942 ShenandoahEvacuationTask(ShenandoahHeap* sh,
943 ShenandoahCollectionSet* cs,
944 bool concurrent) :
945 AbstractGangTask("Parallel Evacuation Task"),
946 _sh(sh),
947 _cs(cs),
948 _concurrent(concurrent)
949 {}
950
951 void work(uint worker_id) {
952 if (_concurrent) {
953 ShenandoahConcurrentWorkerSession worker_session(worker_id);
954 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
955 ShenandoahEvacOOMScope oom_evac_scope;
956 do_work();
957 } else {
958 ShenandoahParallelWorkerSession worker_session(worker_id);
959 ShenandoahEvacOOMScope oom_evac_scope;
960 do_work();
961 }
962 }
963
964 private:
965 void do_work() {
966 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
967 ShenandoahHeapRegion* r;
968 while ((r =_cs->claim_next()) != NULL) {
969 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->region_number());
970 _sh->marked_object_iterate(r, &cl);
971
972 if (ShenandoahPacing) {
973 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
974 }
975
976 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
977 break;
978 }
979 }
980 }
981 };
982
983 void ShenandoahHeap::trash_cset_regions() {
984 ShenandoahHeapLocker locker(lock());
985
986 ShenandoahCollectionSet* set = collection_set();
987 ShenandoahHeapRegion* r;
988 set->clear_current_index();
989 while ((r = set->next()) != NULL) {
990 r->make_trash();
991 }
992 collection_set()->clear();
993 }
994
995 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
996 st->print_cr("Heap Regions:");
997 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
998 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
999 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start (previous, next)");
1000 st->print_cr("SN=alloc sequence numbers (first mutator, last mutator, first gc, last gc)");
1001
1002 for (size_t i = 0; i < num_regions(); i++) {
1003 get_region(i)->print_on(st);
1004 }
1005 }
1006
1007 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1008 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1009
1010 oop humongous_obj = oop(start->bottom());
1011 size_t size = humongous_obj->size();
1012 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1013 size_t index = start->region_number() + required_regions - 1;
1014
1015 assert(!start->has_live(), "liveness must be zero");
1016
1017 for(size_t i = 0; i < required_regions; i++) {
1018 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1019 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1020 ShenandoahHeapRegion* region = get_region(index --);
1021
1022 assert(region->is_humongous(), "expect correct humongous start or continuation");
1023 assert(!region->is_cset(), "Humongous region should not be in collection set");
1024
1025 region->make_trash_immediate();
1026 }
1027 }
1028
1029 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1030 public:
1031 void do_thread(Thread* thread) {
1032 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1033 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1034 gclab->retire();
1035 }
1036 };
1037
1038 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
1039 if (UseTLAB) {
1040 CollectedHeap::ensure_parsability(retire_tlabs);
1041 }
1042 ShenandoahRetireGCLABClosure cl;
1043 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1044 cl.do_thread(t);
1045 }
1046 workers()->threads_do(&cl);
1047 }
1048
1049 void ShenandoahHeap::resize_tlabs() {
1050 CollectedHeap::resize_all_tlabs();
1051 }
1052
1053 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1054 private:
1055 ShenandoahRootEvacuator* _rp;
1056
1057 public:
1058 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1059 AbstractGangTask("Shenandoah evacuate and update roots"),
1060 _rp(rp) {}
1061
1062 void work(uint worker_id) {
1063 ShenandoahParallelWorkerSession worker_session(worker_id);
1064 ShenandoahEvacOOMScope oom_evac_scope;
1065 ShenandoahEvacuateUpdateRootsClosure cl;
1066 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1067 _rp->roots_do(worker_id, &cl);
1068 }
1069 };
1070
1071 void ShenandoahHeap::evacuate_and_update_roots() {
1072 #if COMPILER2_OR_JVMCI
1073 DerivedPointerTable::clear();
1074 #endif
1075 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1076 {
1077 // Include concurrent roots if current cycle can not process those roots concurrently
1078 ShenandoahRootEvacuator rp(workers()->active_workers(),
1079 ShenandoahPhaseTimings::init_evac,
1080 !ShenandoahConcurrentRoots::should_do_concurrent_roots(),
1081 !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
1082 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1083 workers()->run_task(&roots_task);
1084 }
1085
1086 #if COMPILER2_OR_JVMCI
1087 DerivedPointerTable::update_pointers();
1088 #endif
1089 }
1090
1091 // Returns size in bytes
1092 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1093 if (ShenandoahElasticTLAB) {
1094 // With Elastic TLABs, return the max allowed size, and let the allocation path
1095 // figure out the safe size for current allocation.
1096 return ShenandoahHeapRegion::max_tlab_size_bytes();
1097 } else {
1098 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1099 }
1100 }
1101
1102 size_t ShenandoahHeap::max_tlab_size() const {
1103 // Returns size in words
1104 return ShenandoahHeapRegion::max_tlab_size_words();
1105 }
1106
1107 class ShenandoahRetireAndResetGCLABClosure : public ThreadClosure {
1108 public:
1109 void do_thread(Thread* thread) {
1110 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1111 gclab->retire();
1112 if (ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1113 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1114 }
1115 }
1116 };
1117
1118 void ShenandoahHeap::retire_and_reset_gclabs() {
1119 ShenandoahRetireAndResetGCLABClosure cl;
1120 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1121 cl.do_thread(t);
1122 }
1123 workers()->threads_do(&cl);
1124 }
1125
1126 void ShenandoahHeap::collect(GCCause::Cause cause) {
1127 control_thread()->request_gc(cause);
1128 }
1129
1130 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1131 //assert(false, "Shouldn't need to do full collections");
1132 }
1133
1134 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1135 Space* sp = heap_region_containing(addr);
1136 if (sp != NULL) {
1137 return sp->block_start(addr);
1138 }
1139 return NULL;
1140 }
1141
1142 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1143 Space* sp = heap_region_containing(addr);
1144 return sp->block_is_obj(addr);
1145 }
1146
1147 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1148 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1149 }
1150
1151 jlong ShenandoahHeap::millis_since_last_gc() {
1152 double v = heuristics()->time_since_last_gc() * 1000;
1153 assert(0 <= v && v <= max_jlong, "value should fit: %f", v);
1154 return (jlong)v;
1155 }
1156
1157 void ShenandoahHeap::prepare_for_verify() {
1158 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1159 make_parsable(false);
1160 }
1161 }
1162
1163 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1164 workers()->print_worker_threads_on(st);
1165 if (ShenandoahStringDedup::is_enabled()) {
1166 ShenandoahStringDedup::print_worker_threads_on(st);
1167 }
1168 }
1169
1170 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1171 workers()->threads_do(tcl);
1172 if (_safepoint_workers != NULL) {
1173 _safepoint_workers->threads_do(tcl);
1174 }
1175 if (ShenandoahStringDedup::is_enabled()) {
1176 ShenandoahStringDedup::threads_do(tcl);
1177 }
1178 }
1179
1180 void ShenandoahHeap::print_tracing_info() const {
1181 LogTarget(Info, gc, stats) lt;
1182 if (lt.is_enabled()) {
1183 ResourceMark rm;
1184 LogStream ls(lt);
1185
1186 phase_timings()->print_on(&ls);
1187
1188 ls.cr();
1189 ls.cr();
1190
1191 shenandoah_policy()->print_gc_stats(&ls);
1192
1193 ls.cr();
1194 ls.cr();
1195
1196 if (ShenandoahPacing) {
1197 pacer()->print_on(&ls);
1198 }
1199
1200 ls.cr();
1201 ls.cr();
1202
1203 if (ShenandoahAllocationTrace) {
1204 assert(alloc_tracker() != NULL, "Must be");
1205 alloc_tracker()->print_on(&ls);
1206 } else {
1207 ls.print_cr(" Allocation tracing is disabled, use -XX:+ShenandoahAllocationTrace to enable.");
1208 }
1209 }
1210 }
1211
1212 void ShenandoahHeap::verify(VerifyOption vo) {
1213 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1214 if (ShenandoahVerify) {
1215 verifier()->verify_generic(vo);
1216 } else {
1217 // TODO: Consider allocating verification bitmaps on demand,
1218 // and turn this on unconditionally.
1219 }
1220 }
1221 }
1222 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1223 return _free_set->capacity();
1224 }
1225
1226 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1227 private:
1228 MarkBitMap* _bitmap;
1229 Stack<oop,mtGC>* _oop_stack;
1230
1231 template <class T>
1232 void do_oop_work(T* p) {
1233 T o = RawAccess<>::oop_load(p);
1234 if (!CompressedOops::is_null(o)) {
1235 oop obj = CompressedOops::decode_not_null(o);
1236 oop fwd = (oop) ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
1237 if (fwd == NULL) {
1238 // There is an odd interaction with VM_HeapWalkOperation, see jvmtiTagMap.cpp.
1239 //
1240 // That operation walks the reachable objects on its own, storing the marking
1241 // wavefront in the object marks. When it is done, it calls the CollectedHeap
1242 // to iterate over all objects to clean up the mess. When it reaches here,
1243 // the Shenandoah fwdptr resolution code encounters the marked objects with
1244 // NULL forwardee. Trying to act on that would crash the VM. Or fail the
1245 // asserts, should we go for resolve_forwarded_pointer(obj).
1246 //
1247 // Therefore, we have to dodge it by doing the raw access to forwardee, and
1248 // assuming the object had no forwardee, if that thing is NULL.
1249 } else {
1250 obj = fwd;
1251 }
1252 assert(oopDesc::is_oop(obj), "must be a valid oop");
1253 if (!_bitmap->is_marked((HeapWord*) obj)) {
1254 _bitmap->mark((HeapWord*) obj);
1255 _oop_stack->push(obj);
1256 }
1257 }
1258 }
1259 public:
1260 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1261 _bitmap(bitmap), _oop_stack(oop_stack) {}
1262 void do_oop(oop* p) { do_oop_work(p); }
1263 void do_oop(narrowOop* p) { do_oop_work(p); }
1264 };
1265
1266 /*
1267 * This is public API, used in preparation of object_iterate().
1268 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1269 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1270 * control, we call SH::make_tlabs_parsable().
1271 */
1272 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1273 // No-op.
1274 }
1275
1276 /*
1277 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1278 *
1279 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1280 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1281 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1282 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1283 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1284 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1285 * wiped the bitmap in preparation for next marking).
1286 *
1287 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1288 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1289 * is allowed to report dead objects, but is not required to do so.
1290 */
1291 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1292 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1293 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1294 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1295 return;
1296 }
1297
1298 // Reset bitmap
1299 _aux_bit_map.clear();
1300
1301 Stack<oop,mtGC> oop_stack;
1302
1303 // First, we process GC roots according to current GC cycle. This populates the work stack with initial objects.
1304 ShenandoahHeapIterationRootScanner rp;
1305 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1306
1307 // If we are unloading classes right now, we should not touch weak roots,
1308 // on the off-chance we would evacuate them and make them live accidentally.
1309 // In other cases, we have to scan all roots.
1310 if (is_evacuation_in_progress() && unload_classes()) {
1311 rp.strong_roots_do(&oops);
1312 } else {
1313 rp.roots_do(&oops);
1314 }
1315
1316 // Work through the oop stack to traverse heap.
1317 while (! oop_stack.is_empty()) {
1318 oop obj = oop_stack.pop();
1319 assert(oopDesc::is_oop(obj), "must be a valid oop");
1320 cl->do_object(obj);
1321 obj->oop_iterate(&oops);
1322 }
1323
1324 assert(oop_stack.is_empty(), "should be empty");
1325
1326 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1327 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1328 }
1329 }
1330
1331 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1332 void ShenandoahHeap::keep_alive(oop obj) {
1333 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1334 }
1335
1336 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1337 for (size_t i = 0; i < num_regions(); i++) {
1338 ShenandoahHeapRegion* current = get_region(i);
1339 blk->heap_region_do(current);
1340 }
1341 }
1342
1343 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1344 private:
1345 ShenandoahHeap* const _heap;
1346 ShenandoahHeapRegionClosure* const _blk;
1347
1348 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));
1349 volatile size_t _index;
1350 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
1351
1352 public:
1353 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1354 AbstractGangTask("Parallel Region Task"),
1355 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1356
1357 void work(uint worker_id) {
1358 size_t stride = ShenandoahParallelRegionStride;
1359
1360 size_t max = _heap->num_regions();
1361 while (_index < max) {
1362 size_t cur = Atomic::add(&_index, stride) - stride;
1363 size_t start = cur;
1364 size_t end = MIN2(cur + stride, max);
1365 if (start >= max) break;
1366
1367 for (size_t i = cur; i < end; i++) {
1368 ShenandoahHeapRegion* current = _heap->get_region(i);
1369 _blk->heap_region_do(current);
1370 }
1371 }
1372 }
1373 };
1374
1375 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1376 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1377 if (num_regions() > ShenandoahParallelRegionStride) {
1378 ShenandoahParallelHeapRegionTask task(blk);
1379 workers()->run_task(&task);
1380 } else {
1381 heap_region_iterate(blk);
1382 }
1383 }
1384
1385 class ShenandoahClearLivenessClosure : public ShenandoahHeapRegionClosure {
1386 private:
1387 ShenandoahMarkingContext* const _ctx;
1388 public:
1389 ShenandoahClearLivenessClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1390
1391 void heap_region_do(ShenandoahHeapRegion* r) {
1392 if (r->is_active()) {
1393 r->clear_live_data();
1394 _ctx->capture_top_at_mark_start(r);
1395 } else {
1396 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1397 assert(_ctx->top_at_mark_start(r) == r->top(),
1398 "Region " SIZE_FORMAT " should already have correct TAMS", r->region_number());
1399 }
1400 }
1401
1402 bool is_thread_safe() { return true; }
1403 };
1404
1405 void ShenandoahHeap::op_init_mark() {
1406 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1407 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1408
1409 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1410 assert(!marking_context()->is_complete(), "should not be complete");
1411
1412 if (ShenandoahVerify) {
1413 verifier()->verify_before_concmark();
1414 }
1415
1416 if (VerifyBeforeGC) {
1417 Universe::verify();
1418 }
1419
1420 set_concurrent_mark_in_progress(true);
1421 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1422 {
1423 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1424 make_parsable(true);
1425 }
1426
1427 {
1428 ShenandoahGCPhase phase(ShenandoahPhaseTimings::clear_liveness);
1429 ShenandoahClearLivenessClosure clc;
1430 parallel_heap_region_iterate(&clc);
1431 }
1432
1433 // Make above changes visible to worker threads
1434 OrderAccess::fence();
1435
1436 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1437
1438 if (UseTLAB) {
1439 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1440 resize_tlabs();
1441 }
1442
1443 if (ShenandoahPacing) {
1444 pacer()->setup_for_mark();
1445 }
1446 }
1447
1448 void ShenandoahHeap::op_mark() {
1449 concurrent_mark()->mark_from_roots();
1450 }
1451
1452 class ShenandoahCompleteLivenessClosure : public ShenandoahHeapRegionClosure {
1453 private:
1454 ShenandoahMarkingContext* const _ctx;
1455 public:
1456 ShenandoahCompleteLivenessClosure() : _ctx(ShenandoahHeap::heap()->complete_marking_context()) {}
1457
1458 void heap_region_do(ShenandoahHeapRegion* r) {
1459 if (r->is_active()) {
1460 HeapWord *tams = _ctx->top_at_mark_start(r);
1461 HeapWord *top = r->top();
1462 if (top > tams) {
1463 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1464 }
1465 } else {
1466 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1467 assert(_ctx->top_at_mark_start(r) == r->top(),
1468 "Region " SIZE_FORMAT " should have correct TAMS", r->region_number());
1469 }
1470 }
1471
1472 bool is_thread_safe() { return true; }
1473 };
1474
1475 void ShenandoahHeap::op_final_mark() {
1476 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1477
1478 // It is critical that we
1479 // evacuate roots right after finishing marking, so that we don't
1480 // get unmarked objects in the roots.
1481
1482 if (!cancelled_gc()) {
1483 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1484
1485 // Marking is completed, deactivate SATB barrier
1486 set_concurrent_mark_in_progress(false);
1487 mark_complete_marking_context();
1488
1489 parallel_cleaning(false /* full gc*/);
1490
1491 if (has_forwarded_objects()) {
1492 // Degen may be caused by failed evacuation of roots
1493 if (is_degenerated_gc_in_progress()) {
1494 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
1495 } else {
1496 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::update_roots);
1497 }
1498 set_has_forwarded_objects(false);
1499 }
1500
1501 if (ShenandoahVerify) {
1502 verifier()->verify_roots_no_forwarded();
1503 }
1504 // All allocations past TAMS are implicitly live, adjust the region data.
1505 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1506 {
1507 ShenandoahGCPhase phase(ShenandoahPhaseTimings::complete_liveness);
1508 ShenandoahCompleteLivenessClosure cl;
1509 parallel_heap_region_iterate(&cl);
1510 }
1511
1512 // Force the threads to reacquire their TLABs outside the collection set.
1513 {
1514 ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs);
1515 make_parsable(true);
1516 }
1517
1518 // We are about to select the collection set, make sure it knows about
1519 // current pinning status. Also, this allows trashing more regions that
1520 // now have their pinning status dropped.
1521 {
1522 ShenandoahGCPhase phase(ShenandoahPhaseTimings::sync_pinned);
1523 sync_pinned_region_status();
1524 }
1525
1526 // Trash the collection set left over from previous cycle, if any.
1527 {
1528 ShenandoahGCPhase phase(ShenandoahPhaseTimings::trash_cset);
1529 trash_cset_regions();
1530 }
1531
1532 {
1533 ShenandoahGCPhase phase(ShenandoahPhaseTimings::prepare_evac);
1534
1535 ShenandoahHeapLocker locker(lock());
1536 _collection_set->clear();
1537 _free_set->clear();
1538
1539 heuristics()->choose_collection_set(_collection_set);
1540
1541 _free_set->rebuild();
1542 }
1543
1544 if (!is_degenerated_gc_in_progress()) {
1545 prepare_concurrent_roots();
1546 prepare_concurrent_unloading();
1547 }
1548
1549 // If collection set has candidates, start evacuation.
1550 // Otherwise, bypass the rest of the cycle.
1551 if (!collection_set()->is_empty()) {
1552 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1553
1554 if (ShenandoahVerify) {
1555 verifier()->verify_before_evacuation();
1556 }
1557
1558 set_evacuation_in_progress(true);
1559 // From here on, we need to update references.
1560 set_has_forwarded_objects(true);
1561
1562 if (!is_degenerated_gc_in_progress()) {
1563 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1564 ShenandoahCodeRoots::arm_nmethods();
1565 }
1566 evacuate_and_update_roots();
1567 }
1568
1569 if (ShenandoahPacing) {
1570 pacer()->setup_for_evac();
1571 }
1572
1573 if (ShenandoahVerify) {
1574 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::None;
1575 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1576 types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots);
1577 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots);
1578 }
1579
1580 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1581 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CodeRoots);
1582 }
1583 verifier()->verify_roots_no_forwarded_except(types);
1584 verifier()->verify_during_evacuation();
1585 }
1586 } else {
1587 if (ShenandoahVerify) {
1588 verifier()->verify_after_concmark();
1589 }
1590
1591 if (VerifyAfterGC) {
1592 Universe::verify();
1593 }
1594 }
1595
1596 } else {
1597 // If this cycle was updating references, we need to keep the has_forwarded_objects
1598 // flag on, for subsequent phases to deal with it.
1599 concurrent_mark()->cancel();
1600 set_concurrent_mark_in_progress(false);
1601
1602 if (process_references()) {
1603 // Abandon reference processing right away: pre-cleaning must have failed.
1604 ReferenceProcessor *rp = ref_processor();
1605 rp->disable_discovery();
1606 rp->abandon_partial_discovery();
1607 rp->verify_no_references_recorded();
1608 }
1609 }
1610 }
1611
1612 void ShenandoahHeap::op_final_evac() {
1613 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1614
1615 set_evacuation_in_progress(false);
1616
1617 {
1618 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_retire_gclabs);
1619 retire_and_reset_gclabs();
1620 }
1621
1622 if (ShenandoahVerify) {
1623 verifier()->verify_after_evacuation();
1624 }
1625
1626 if (VerifyAfterGC) {
1627 Universe::verify();
1628 }
1629 }
1630
1631 void ShenandoahHeap::op_conc_evac() {
1632 ShenandoahEvacuationTask task(this, _collection_set, true);
1633 workers()->run_task(&task);
1634 }
1635
1636 void ShenandoahHeap::op_stw_evac() {
1637 ShenandoahEvacuationTask task(this, _collection_set, false);
1638 workers()->run_task(&task);
1639 }
1640
1641 void ShenandoahHeap::op_updaterefs() {
1642 update_heap_references(true);
1643 }
1644
1645 void ShenandoahHeap::op_cleanup() {
1646 free_set()->recycle_trash();
1647 }
1648
1649 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask {
1650 private:
1651 ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
1652 ShenandoahWeakRoots<true /*concurrent*/> _weak_roots;
1653 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots;
1654
1655 public:
1656 ShenandoahConcurrentRootsEvacUpdateTask() :
1657 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Roots Task") {
1658 }
1659
1660 void work(uint worker_id) {
1661 ShenandoahEvacOOMScope oom;
1662 {
1663 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
1664 // may race against OopStorage::release() calls.
1665 ShenandoahEvacUpdateOopStorageRootsClosure cl;
1666 _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1667 _weak_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1668 }
1669
1670 {
1671 ShenandoahEvacuateUpdateRootsClosure cl;
1672 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1673 _cld_roots.cld_do(&clds);
1674 }
1675 }
1676 };
1677
1678 void ShenandoahHeap::op_roots() {
1679 if (is_concurrent_root_in_progress()) {
1680 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1681 _unloader.unload();
1682 }
1683
1684 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1685 ShenandoahConcurrentRootsEvacUpdateTask task;
1686 workers()->run_task(&task);
1687 }
1688 }
1689
1690 set_concurrent_root_in_progress(false);
1691 }
1692
1693 void ShenandoahHeap::op_reset() {
1694 reset_mark_bitmap();
1695 }
1696
1697 void ShenandoahHeap::op_preclean() {
1698 concurrent_mark()->preclean_weak_refs();
1699 }
1700
1701 void ShenandoahHeap::op_init_traversal() {
1702 traversal_gc()->init_traversal_collection();
1703 }
1704
1705 void ShenandoahHeap::op_traversal() {
1706 traversal_gc()->concurrent_traversal_collection();
1707 }
1708
1709 void ShenandoahHeap::op_final_traversal() {
1710 traversal_gc()->final_traversal_collection();
1711 }
1712
1713 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1714 ShenandoahMetricsSnapshot metrics;
1715 metrics.snap_before();
1716
1717 full_gc()->do_it(cause);
1718 if (UseTLAB) {
1719 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs);
1720 resize_all_tlabs();
1721 }
1722
1723 metrics.snap_after();
1724
1725 if (metrics.is_good_progress()) {
1726 _progress_last_gc.set();
1727 } else {
1728 // Nothing to do. Tell the allocation path that we have failed to make
1729 // progress, and it can finally fail.
1730 _progress_last_gc.unset();
1731 }
1732 }
1733
1734 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1735 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1736 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1737 // some phase, we have to upgrade the Degenerate GC to Full GC.
1738
1739 clear_cancelled_gc();
1740
1741 ShenandoahMetricsSnapshot metrics;
1742 metrics.snap_before();
1743
1744 switch (point) {
1745 case _degenerated_traversal:
1746 {
1747 // Drop the collection set. Note: this leaves some already forwarded objects
1748 // behind, which may be problematic, see comments for ShenandoahEvacAssist
1749 // workarounds in ShenandoahTraversalHeuristics.
1750
1751 ShenandoahHeapLocker locker(lock());
1752 collection_set()->clear_current_index();
1753 for (size_t i = 0; i < collection_set()->count(); i++) {
1754 ShenandoahHeapRegion* r = collection_set()->next();
1755 r->make_regular_bypass();
1756 }
1757 collection_set()->clear();
1758 }
1759 op_final_traversal();
1760 op_cleanup();
1761 return;
1762
1763 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1764 // but enters it at different points, depending on which concurrent phase had
1765 // degenerated.
1766
1767 case _degenerated_outside_cycle:
1768 // We have degenerated from outside the cycle, which means something is bad with
1769 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1770 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1771 // we can do the most aggressive degen cycle, which includes processing references and
1772 // class unloading, unless those features are explicitly disabled.
1773 //
1774 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1775 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1776 set_process_references(heuristics()->can_process_references());
1777 set_unload_classes(heuristics()->can_unload_classes());
1778
1779 if (is_traversal_mode()) {
1780 // Not possible to degenerate from here, upgrade to Full GC right away.
1781 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1782 op_degenerated_fail();
1783 return;
1784 }
1785
1786 op_reset();
1787
1788 op_init_mark();
1789 if (cancelled_gc()) {
1790 op_degenerated_fail();
1791 return;
1792 }
1793
1794 case _degenerated_mark:
1795 op_final_mark();
1796 if (cancelled_gc()) {
1797 op_degenerated_fail();
1798 return;
1799 }
1800
1801 op_cleanup();
1802
1803 case _degenerated_evac:
1804 // If heuristics thinks we should do the cycle, this flag would be set,
1805 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
1806 if (is_evacuation_in_progress()) {
1807
1808 // Degeneration under oom-evac protocol might have left some objects in
1809 // collection set un-evacuated. Restart evacuation from the beginning to
1810 // capture all objects. For all the objects that are already evacuated,
1811 // it would be a simple check, which is supposed to be fast. This is also
1812 // safe to do even without degeneration, as CSet iterator is at beginning
1813 // in preparation for evacuation anyway.
1814 //
1815 // Before doing that, we need to make sure we never had any cset-pinned
1816 // regions. This may happen if allocation failure happened when evacuating
1817 // the about-to-be-pinned object, oom-evac protocol left the object in
1818 // the collection set, and then the pin reached the cset region. If we continue
1819 // the cycle here, we would trash the cset and alive objects in it. To avoid
1820 // it, we fail degeneration right away and slide into Full GC to recover.
1821
1822 {
1823 sync_pinned_region_status();
1824 collection_set()->clear_current_index();
1825
1826 ShenandoahHeapRegion* r;
1827 while ((r = collection_set()->next()) != NULL) {
1828 if (r->is_pinned()) {
1829 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1830 op_degenerated_fail();
1831 return;
1832 }
1833 }
1834
1835 collection_set()->clear_current_index();
1836 }
1837
1838 op_stw_evac();
1839 if (cancelled_gc()) {
1840 op_degenerated_fail();
1841 return;
1842 }
1843 }
1844
1845 // If heuristics thinks we should do the cycle, this flag would be set,
1846 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
1847 if (has_forwarded_objects()) {
1848 op_init_updaterefs();
1849 if (cancelled_gc()) {
1850 op_degenerated_fail();
1851 return;
1852 }
1853 }
1854
1855 case _degenerated_updaterefs:
1856 if (has_forwarded_objects()) {
1857 op_final_updaterefs();
1858 if (cancelled_gc()) {
1859 op_degenerated_fail();
1860 return;
1861 }
1862 }
1863
1864 op_cleanup();
1865 break;
1866
1867 default:
1868 ShouldNotReachHere();
1869 }
1870
1871 if (ShenandoahVerify) {
1872 verifier()->verify_after_degenerated();
1873 }
1874
1875 if (VerifyAfterGC) {
1876 Universe::verify();
1877 }
1878
1879 metrics.snap_after();
1880
1881 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
1882 // because that probably means the heap is overloaded and/or fragmented.
1883 if (!metrics.is_good_progress()) {
1884 _progress_last_gc.unset();
1885 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1886 op_degenerated_futile();
1887 } else {
1888 _progress_last_gc.set();
1889 }
1890 }
1891
1892 void ShenandoahHeap::op_degenerated_fail() {
1893 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
1894 shenandoah_policy()->record_degenerated_upgrade_to_full();
1895 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1896 }
1897
1898 void ShenandoahHeap::op_degenerated_futile() {
1899 shenandoah_policy()->record_degenerated_upgrade_to_full();
1900 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1901 }
1902
1903 void ShenandoahHeap::force_satb_flush_all_threads() {
1904 if (!is_concurrent_mark_in_progress() && !is_concurrent_traversal_in_progress()) {
1905 // No need to flush SATBs
1906 return;
1907 }
1908
1909 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1910 ShenandoahThreadLocalData::set_force_satb_flush(t, true);
1911 }
1912 // The threads are not "acquiring" their thread-local data, but it does not
1913 // hurt to "release" the updates here anyway.
1914 OrderAccess::fence();
1915 }
1916
1917 void ShenandoahHeap::set_gc_state_all_threads(char state) {
1918 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1919 ShenandoahThreadLocalData::set_gc_state(t, state);
1920 }
1921 }
1922
1923 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1924 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1925 _gc_state.set_cond(mask, value);
1926 set_gc_state_all_threads(_gc_state.raw_value());
1927 }
1928
1929 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1930 if (has_forwarded_objects()) {
1931 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
1932 } else {
1933 set_gc_state_mask(MARKING, in_progress);
1934 }
1935 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1936 }
1937
1938 void ShenandoahHeap::set_concurrent_traversal_in_progress(bool in_progress) {
1939 set_gc_state_mask(TRAVERSAL, in_progress);
1940 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1941 }
1942
1943 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1944 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1945 set_gc_state_mask(EVACUATION, in_progress);
1946 }
1947
1948 void ShenandoahHeap::set_concurrent_root_in_progress(bool in_progress) {
1949 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
1950 if (in_progress) {
1951 _concurrent_root_in_progress.set();
1952 } else {
1953 _concurrent_root_in_progress.unset();
1954 }
1955 }
1956
1957 void ShenandoahHeap::ref_processing_init() {
1958 assert(_max_workers > 0, "Sanity");
1959
1960 _ref_processor =
1961 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
1962 ParallelRefProcEnabled, // MT processing
1963 _max_workers, // Degree of MT processing
1964 true, // MT discovery
1965 _max_workers, // Degree of MT discovery
1966 false, // Reference discovery is not atomic
1967 NULL, // No closure, should be installed before use
1968 true); // Scale worker threads
1969
1970 shenandoah_assert_rp_isalive_not_installed();
1971 }
1972
1973 GCTracer* ShenandoahHeap::tracer() {
1974 return shenandoah_policy()->tracer();
1975 }
1976
1977 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1978 return _free_set->used();
1979 }
1980
1981 bool ShenandoahHeap::try_cancel_gc() {
1982 while (true) {
1983 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1984 if (prev == CANCELLABLE) return true;
1985 else if (prev == CANCELLED) return false;
1986 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
1987 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
1988 if (Thread::current()->is_Java_thread()) {
1989 // We need to provide a safepoint here, otherwise we might
1990 // spin forever if a SP is pending.
1991 ThreadBlockInVM sp(JavaThread::current());
1992 SpinPause();
1993 }
1994 }
1995 }
1996
1997 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1998 if (try_cancel_gc()) {
1999 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
2000 log_info(gc)("%s", msg.buffer());
2001 Events::log(Thread::current(), "%s", msg.buffer());
2002 }
2003 }
2004
2005 uint ShenandoahHeap::max_workers() {
2006 return _max_workers;
2007 }
2008
2009 void ShenandoahHeap::stop() {
2010 // The shutdown sequence should be able to terminate when GC is running.
2011
2012 // Step 0. Notify policy to disable event recording.
2013 _shenandoah_policy->record_shutdown();
2014
2015 // Step 1. Notify control thread that we are in shutdown.
2016 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
2017 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
2018 control_thread()->prepare_for_graceful_shutdown();
2019
2020 // Step 2. Notify GC workers that we are cancelling GC.
2021 cancel_gc(GCCause::_shenandoah_stop_vm);
2022
2023 // Step 3. Wait until GC worker exits normally.
2024 control_thread()->stop();
2025
2026 // Step 4. Stop String Dedup thread if it is active
2027 if (ShenandoahStringDedup::is_enabled()) {
2028 ShenandoahStringDedup::stop();
2029 }
2030 }
2031
2032 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
2033 if (!unload_classes()) return;
2034 bool purged_class;
2035
2036 // Unload classes and purge SystemDictionary.
2037 {
2038 ShenandoahGCPhase phase(full_gc ?
2039 ShenandoahPhaseTimings::full_gc_purge_class_unload :
2040 ShenandoahPhaseTimings::purge_class_unload);
2041 purged_class = SystemDictionary::do_unloading(gc_timer());
2042 }
2043
2044 {
2045 ShenandoahGCPhase phase(full_gc ?
2046 ShenandoahPhaseTimings::full_gc_purge_par :
2047 ShenandoahPhaseTimings::purge_par);
2048 ShenandoahIsAliveSelector is_alive;
2049 uint num_workers = _workers->active_workers();
2050 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
2051 _workers->run_task(&unlink_task);
2052 }
2053
2054 {
2055 ShenandoahGCPhase phase(full_gc ?
2056 ShenandoahPhaseTimings::full_gc_purge_cldg :
2057 ShenandoahPhaseTimings::purge_cldg);
2058 ClassLoaderDataGraph::purge();
2059 }
2060 // Resize and verify metaspace
2061 MetaspaceGC::compute_new_size();
2062 MetaspaceUtils::verify_metrics();
2063 }
2064
2065 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
2066 // so they should not have forwarded oops.
2067 // However, we do need to "null" dead oops in the roots, if can not be done
2068 // in concurrent cycles.
2069 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
2070 ShenandoahGCPhase root_phase(full_gc ?
2071 ShenandoahPhaseTimings::full_gc_purge :
2072 ShenandoahPhaseTimings::purge);
2073 uint num_workers = _workers->active_workers();
2074 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
2075 ShenandoahPhaseTimings::full_gc_purge_par :
2076 ShenandoahPhaseTimings::purge_par;
2077 // Cleanup weak roots
2078 ShenandoahGCPhase phase(timing_phase);
2079 if (has_forwarded_objects()) {
2080 if (is_traversal_mode()) {
2081 ShenandoahForwardedIsAliveClosure is_alive;
2082 ShenandoahTraversalUpdateRefsClosure keep_alive;
2083 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahTraversalUpdateRefsClosure>
2084 cleaning_task(&is_alive, &keep_alive, num_workers);
2085 _workers->run_task(&cleaning_task);
2086 } else {
2087 ShenandoahForwardedIsAliveClosure is_alive;
2088 ShenandoahUpdateRefsClosure keep_alive;
2089 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2090 cleaning_task(&is_alive, &keep_alive, num_workers);
2091 _workers->run_task(&cleaning_task);
2092 }
2093 } else {
2094 ShenandoahIsAliveClosure is_alive;
2095 #ifdef ASSERT
2096 ShenandoahAssertNotForwardedClosure verify_cl;
2097 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2098 cleaning_task(&is_alive, &verify_cl, num_workers);
2099 #else
2100 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2101 cleaning_task(&is_alive, &do_nothing_cl, num_workers);
2102 #endif
2103 _workers->run_task(&cleaning_task);
2104 }
2105 }
2106
2107 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2108 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2109 stw_process_weak_roots(full_gc);
2110 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2111 stw_unload_classes(full_gc);
2112 }
2113 }
2114
2115 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2116 if (is_traversal_mode()) {
2117 set_gc_state_mask(HAS_FORWARDED | UPDATEREFS, cond);
2118 } else {
2119 set_gc_state_mask(HAS_FORWARDED, cond);
2120 }
2121
2122 }
2123
2124 void ShenandoahHeap::set_process_references(bool pr) {
2125 _process_references.set_cond(pr);
2126 }
2127
2128 void ShenandoahHeap::set_unload_classes(bool uc) {
2129 _unload_classes.set_cond(uc);
2130 }
2131
2132 bool ShenandoahHeap::process_references() const {
2133 return _process_references.is_set();
2134 }
2135
2136 bool ShenandoahHeap::unload_classes() const {
2137 return _unload_classes.is_set();
2138 }
2139
2140 address ShenandoahHeap::in_cset_fast_test_addr() {
2141 ShenandoahHeap* heap = ShenandoahHeap::heap();
2142 assert(heap->collection_set() != NULL, "Sanity");
2143 return (address) heap->collection_set()->biased_map_address();
2144 }
2145
2146 address ShenandoahHeap::cancelled_gc_addr() {
2147 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
2148 }
2149
2150 address ShenandoahHeap::gc_state_addr() {
2151 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2152 }
2153
2154 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2155 return Atomic::load_acquire(&_bytes_allocated_since_gc_start);
2156 }
2157
2158 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2159 Atomic::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2160 }
2161
2162 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2163 _degenerated_gc_in_progress.set_cond(in_progress);
2164 }
2165
2166 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2167 _full_gc_in_progress.set_cond(in_progress);
2168 }
2169
2170 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2171 assert (is_full_gc_in_progress(), "should be");
2172 _full_gc_move_in_progress.set_cond(in_progress);
2173 }
2174
2175 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2176 set_gc_state_mask(UPDATEREFS, in_progress);
2177 }
2178
2179 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2180 ShenandoahCodeRoots::register_nmethod(nm);
2181 }
2182
2183 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2184 ShenandoahCodeRoots::unregister_nmethod(nm);
2185 }
2186
2187 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
2188 ShenandoahCodeRoots::flush_nmethod(nm);
2189 }
2190
2191 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2192 heap_region_containing(o)->record_pin();
2193 return o;
2194 }
2195
2196 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2197 heap_region_containing(o)->record_unpin();
2198 }
2199
2200 void ShenandoahHeap::sync_pinned_region_status() {
2201 ShenandoahHeapLocker locker(lock());
2202
2203 for (size_t i = 0; i < num_regions(); i++) {
2204 ShenandoahHeapRegion *r = get_region(i);
2205 if (r->is_active()) {
2206 if (r->is_pinned()) {
2207 if (r->pin_count() == 0) {
2208 r->make_unpinned();
2209 }
2210 } else {
2211 if (r->pin_count() > 0) {
2212 r->make_pinned();
2213 }
2214 }
2215 }
2216 }
2217
2218 assert_pinned_region_status();
2219 }
2220
2221 #ifdef ASSERT
2222 void ShenandoahHeap::assert_pinned_region_status() {
2223 for (size_t i = 0; i < num_regions(); i++) {
2224 ShenandoahHeapRegion* r = get_region(i);
2225 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2226 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2227 }
2228 }
2229 #endif
2230
2231 GCTimer* ShenandoahHeap::gc_timer() const {
2232 return _gc_timer;
2233 }
2234
2235 void ShenandoahHeap::prepare_concurrent_roots() {
2236 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2237 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
2238 set_concurrent_root_in_progress(true);
2239 }
2240 }
2241
2242 void ShenandoahHeap::prepare_concurrent_unloading() {
2243 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2244 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2245 _unloader.prepare();
2246 }
2247 }
2248
2249 void ShenandoahHeap::finish_concurrent_unloading() {
2250 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2251 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2252 _unloader.finish();
2253 }
2254 }
2255
2256 #ifdef ASSERT
2257 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2258 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2259
2260 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2261 if (UseDynamicNumberOfGCThreads ||
2262 (FLAG_IS_DEFAULT(ParallelGCThreads) && ForceDynamicNumberOfGCThreads)) {
2263 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2264 } else {
2265 // Use ParallelGCThreads inside safepoints
2266 assert(nworkers == ParallelGCThreads, "Use ParalleGCThreads within safepoints");
2267 }
2268 } else {
2269 if (UseDynamicNumberOfGCThreads ||
2270 (FLAG_IS_DEFAULT(ConcGCThreads) && ForceDynamicNumberOfGCThreads)) {
2271 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2272 } else {
2273 // Use ConcGCThreads outside safepoints
2274 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2275 }
2276 }
2277 }
2278 #endif
2279
2280 ShenandoahVerifier* ShenandoahHeap::verifier() {
2281 guarantee(ShenandoahVerify, "Should be enabled");
2282 assert (_verifier != NULL, "sanity");
2283 return _verifier;
2284 }
2285
2286 template<class T>
2287 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2288 private:
2289 T cl;
2290 ShenandoahHeap* _heap;
2291 ShenandoahRegionIterator* _regions;
2292 bool _concurrent;
2293 public:
2294 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2295 AbstractGangTask("Concurrent Update References Task"),
2296 cl(T()),
2297 _heap(ShenandoahHeap::heap()),
2298 _regions(regions),
2299 _concurrent(concurrent) {
2300 }
2301
2302 void work(uint worker_id) {
2303 if (_concurrent) {
2304 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2305 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2306 do_work();
2307 } else {
2308 ShenandoahParallelWorkerSession worker_session(worker_id);
2309 do_work();
2310 }
2311 }
2312
2313 private:
2314 void do_work() {
2315 ShenandoahHeapRegion* r = _regions->next();
2316 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2317 while (r != NULL) {
2318 HeapWord* top_at_start_ur = r->concurrent_iteration_safe_limit();
2319 assert (top_at_start_ur >= r->bottom(), "sanity");
2320 if (r->is_active() && !r->is_cset()) {
2321 _heap->marked_object_oop_iterate(r, &cl, top_at_start_ur);
2322 }
2323 if (ShenandoahPacing) {
2324 _heap->pacer()->report_updaterefs(pointer_delta(top_at_start_ur, r->bottom()));
2325 }
2326 if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
2327 return;
2328 }
2329 r = _regions->next();
2330 }
2331 }
2332 };
2333
2334 void ShenandoahHeap::update_heap_references(bool concurrent) {
2335 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
2336 workers()->run_task(&task);
2337 }
2338
2339 void ShenandoahHeap::op_init_updaterefs() {
2340 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2341
2342 set_evacuation_in_progress(false);
2343
2344 {
2345 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_retire_gclabs);
2346 retire_and_reset_gclabs();
2347 }
2348
2349 if (ShenandoahVerify) {
2350 if (!is_degenerated_gc_in_progress()) {
2351 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots);
2352 }
2353 verifier()->verify_before_updaterefs();
2354 }
2355
2356 set_update_refs_in_progress(true);
2357
2358 {
2359 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_prepare);
2360
2361 make_parsable(true);
2362 for (uint i = 0; i < num_regions(); i++) {
2363 ShenandoahHeapRegion* r = get_region(i);
2364 r->set_concurrent_iteration_safe_limit(r->top());
2365 }
2366
2367 // Reset iterator.
2368 _update_refs_iterator.reset();
2369 }
2370
2371 if (ShenandoahPacing) {
2372 pacer()->setup_for_updaterefs();
2373 }
2374 }
2375
2376 void ShenandoahHeap::op_final_updaterefs() {
2377 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2378
2379 finish_concurrent_unloading();
2380
2381 // Check if there is left-over work, and finish it
2382 if (_update_refs_iterator.has_next()) {
2383 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2384
2385 // Finish updating references where we left off.
2386 clear_cancelled_gc();
2387 update_heap_references(false);
2388 }
2389
2390 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2391 // everything. On degenerated paths, cancelled gc would not be set anyway.
2392 if (cancelled_gc()) {
2393 clear_cancelled_gc();
2394 }
2395 assert(!cancelled_gc(), "Should have been done right before");
2396
2397 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2398 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2399 }
2400
2401 if (is_degenerated_gc_in_progress()) {
2402 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2403 } else {
2404 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2405 }
2406
2407 // Has to be done before cset is clear
2408 if (ShenandoahVerify) {
2409 verifier()->verify_roots_in_to_space();
2410 }
2411
2412 // Drop unnecessary "pinned" state from regions that does not have CP marks
2413 // anymore, as this would allow trashing them below.
2414 {
2415 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_sync_pinned);
2416 sync_pinned_region_status();
2417 }
2418
2419 {
2420 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2421 trash_cset_regions();
2422 }
2423
2424 set_has_forwarded_objects(false);
2425 set_update_refs_in_progress(false);
2426
2427 if (ShenandoahVerify) {
2428 verifier()->verify_after_updaterefs();
2429 }
2430
2431 if (VerifyAfterGC) {
2432 Universe::verify();
2433 }
2434
2435 {
2436 ShenandoahHeapLocker locker(lock());
2437 _free_set->rebuild();
2438 }
2439 }
2440
2441 #ifdef ASSERT
2442 void ShenandoahHeap::assert_heaplock_owned_by_current_thread() {
2443 _lock.assert_owned_by_current_thread();
2444 }
2445
2446 void ShenandoahHeap::assert_heaplock_not_owned_by_current_thread() {
2447 _lock.assert_not_owned_by_current_thread();
2448 }
2449
2450 void ShenandoahHeap::assert_heaplock_or_safepoint() {
2451 _lock.assert_owned_by_current_thread_or_safepoint();
2452 }
2453 #endif
2454
2455 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2456 print_on(st);
2457 print_heap_regions_on(st);
2458 }
2459
2460 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2461 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2462
2463 size_t regions_from = _bitmap_regions_per_slice * slice;
2464 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2465 for (size_t g = regions_from; g < regions_to; g++) {
2466 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2467 if (skip_self && g == r->region_number()) continue;
2468 if (get_region(g)->is_committed()) {
2469 return true;
2470 }
2471 }
2472 return false;
2473 }
2474
2475 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2476 assert_heaplock_owned_by_current_thread();
2477
2478 // Bitmaps in special regions do not need commits
2479 if (_bitmap_region_special) {
2480 return true;
2481 }
2482
2483 if (is_bitmap_slice_committed(r, true)) {
2484 // Some other region from the group is already committed, meaning the bitmap
2485 // slice is already committed, we exit right away.
2486 return true;
2487 }
2488
2489 // Commit the bitmap slice:
2490 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2491 size_t off = _bitmap_bytes_per_slice * slice;
2492 size_t len = _bitmap_bytes_per_slice;
2493 if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) {
2494 return false;
2495 }
2496 return true;
2497 }
2498
2499 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2500 assert_heaplock_owned_by_current_thread();
2501
2502 // Bitmaps in special regions do not need uncommits
2503 if (_bitmap_region_special) {
2504 return true;
2505 }
2506
2507 if (is_bitmap_slice_committed(r, true)) {
2508 // Some other region from the group is still committed, meaning the bitmap
2509 // slice is should stay committed, exit right away.
2510 return true;
2511 }
2512
2513 // Uncommit the bitmap slice:
2514 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2515 size_t off = _bitmap_bytes_per_slice * slice;
2516 size_t len = _bitmap_bytes_per_slice;
2517 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2518 return false;
2519 }
2520 return true;
2521 }
2522
2523 void ShenandoahHeap::safepoint_synchronize_begin() {
2524 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2525 SuspendibleThreadSet::synchronize();
2526 }
2527 }
2528
2529 void ShenandoahHeap::safepoint_synchronize_end() {
2530 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2531 SuspendibleThreadSet::desynchronize();
2532 }
2533 }
2534
2535 void ShenandoahHeap::vmop_entry_init_mark() {
2536 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2537 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2538 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
2539
2540 try_inject_alloc_failure();
2541 VM_ShenandoahInitMark op;
2542 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2543 }
2544
2545 void ShenandoahHeap::vmop_entry_final_mark() {
2546 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2547 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2548 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
2549
2550 try_inject_alloc_failure();
2551 VM_ShenandoahFinalMarkStartEvac op;
2552 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2553 }
2554
2555 void ShenandoahHeap::vmop_entry_final_evac() {
2556 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2557 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2558 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_gross);
2559
2560 VM_ShenandoahFinalEvac op;
2561 VMThread::execute(&op); // jump to entry_final_evac under safepoint
2562 }
2563
2564 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2565 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2566 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2567 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
2568
2569 try_inject_alloc_failure();
2570 VM_ShenandoahInitUpdateRefs op;
2571 VMThread::execute(&op);
2572 }
2573
2574 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2575 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2576 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2577 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
2578
2579 try_inject_alloc_failure();
2580 VM_ShenandoahFinalUpdateRefs op;
2581 VMThread::execute(&op);
2582 }
2583
2584 void ShenandoahHeap::vmop_entry_init_traversal() {
2585 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2586 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2587 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc_gross);
2588
2589 try_inject_alloc_failure();
2590 VM_ShenandoahInitTraversalGC op;
2591 VMThread::execute(&op);
2592 }
2593
2594 void ShenandoahHeap::vmop_entry_final_traversal() {
2595 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2596 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2597 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc_gross);
2598
2599 try_inject_alloc_failure();
2600 VM_ShenandoahFinalTraversalGC op;
2601 VMThread::execute(&op);
2602 }
2603
2604 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2605 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2606 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2607 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
2608
2609 try_inject_alloc_failure();
2610 VM_ShenandoahFullGC op(cause);
2611 VMThread::execute(&op);
2612 }
2613
2614 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2615 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2616 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2617 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
2618
2619 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2620 VMThread::execute(°enerated_gc);
2621 }
2622
2623 void ShenandoahHeap::entry_init_mark() {
2624 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2625 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
2626 const char* msg = init_mark_event_message();
2627 GCTraceTime(Info, gc) time(msg, gc_timer());
2628 EventMark em("%s", msg);
2629
2630 ShenandoahWorkerScope scope(workers(),
2631 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2632 "init marking");
2633
2634 op_init_mark();
2635 }
2636
2637 void ShenandoahHeap::entry_final_mark() {
2638 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2639 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
2640 const char* msg = final_mark_event_message();
2641 GCTraceTime(Info, gc) time(msg, gc_timer());
2642 EventMark em("%s", msg);
2643
2644 ShenandoahWorkerScope scope(workers(),
2645 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2646 "final marking");
2647
2648 op_final_mark();
2649 }
2650
2651 void ShenandoahHeap::entry_final_evac() {
2652 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2653 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac);
2654 static const char* msg = "Pause Final Evac";
2655 GCTraceTime(Info, gc) time(msg, gc_timer());
2656 EventMark em("%s", msg);
2657
2658 op_final_evac();
2659 }
2660
2661 void ShenandoahHeap::entry_init_updaterefs() {
2662 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2663 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
2664
2665 static const char* msg = "Pause Init Update Refs";
2666 GCTraceTime(Info, gc) time(msg, gc_timer());
2667 EventMark em("%s", msg);
2668
2669 // No workers used in this phase, no setup required
2670
2671 op_init_updaterefs();
2672 }
2673
2674 void ShenandoahHeap::entry_final_updaterefs() {
2675 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2676 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
2677
2678 static const char* msg = "Pause Final Update Refs";
2679 GCTraceTime(Info, gc) time(msg, gc_timer());
2680 EventMark em("%s", msg);
2681
2682 ShenandoahWorkerScope scope(workers(),
2683 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2684 "final reference update");
2685
2686 op_final_updaterefs();
2687 }
2688
2689 void ShenandoahHeap::entry_init_traversal() {
2690 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2691 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc);
2692
2693 static const char* msg = "Pause Init Traversal";
2694 GCTraceTime(Info, gc) time(msg, gc_timer());
2695 EventMark em("%s", msg);
2696
2697 ShenandoahWorkerScope scope(workers(),
2698 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2699 "init traversal");
2700
2701 op_init_traversal();
2702 }
2703
2704 void ShenandoahHeap::entry_final_traversal() {
2705 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2706 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc);
2707
2708 static const char* msg = "Pause Final Traversal";
2709 GCTraceTime(Info, gc) time(msg, gc_timer());
2710 EventMark em("%s", msg);
2711
2712 ShenandoahWorkerScope scope(workers(),
2713 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2714 "final traversal");
2715
2716 op_final_traversal();
2717 }
2718
2719 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2720 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2721 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
2722
2723 static const char* msg = "Pause Full";
2724 GCTraceTime(Info, gc) time(msg, gc_timer(), cause, true);
2725 EventMark em("%s", msg);
2726
2727 ShenandoahWorkerScope scope(workers(),
2728 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2729 "full gc");
2730
2731 op_full(cause);
2732 }
2733
2734 void ShenandoahHeap::entry_degenerated(int point) {
2735 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2736 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
2737
2738 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2739 const char* msg = degen_event_message(dpoint);
2740 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2741 EventMark em("%s", msg);
2742
2743 ShenandoahWorkerScope scope(workers(),
2744 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2745 "stw degenerated gc");
2746
2747 set_degenerated_gc_in_progress(true);
2748 op_degenerated(dpoint);
2749 set_degenerated_gc_in_progress(false);
2750 }
2751
2752 void ShenandoahHeap::entry_mark() {
2753 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2754
2755 const char* msg = conc_mark_event_message();
2756 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2757 EventMark em("%s", msg);
2758
2759 ShenandoahWorkerScope scope(workers(),
2760 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2761 "concurrent marking");
2762
2763 try_inject_alloc_failure();
2764 op_mark();
2765 }
2766
2767 void ShenandoahHeap::entry_evac() {
2768 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
2769 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2770
2771 static const char* msg = "Concurrent evacuation";
2772 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2773 EventMark em("%s", msg);
2774
2775 ShenandoahWorkerScope scope(workers(),
2776 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2777 "concurrent evacuation");
2778
2779 try_inject_alloc_failure();
2780 op_conc_evac();
2781 }
2782
2783 void ShenandoahHeap::entry_updaterefs() {
2784 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
2785
2786 static const char* msg = "Concurrent update references";
2787 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2788 EventMark em("%s", msg);
2789
2790 ShenandoahWorkerScope scope(workers(),
2791 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2792 "concurrent reference update");
2793
2794 try_inject_alloc_failure();
2795 op_updaterefs();
2796 }
2797
2798 void ShenandoahHeap::entry_roots() {
2799 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_roots);
2800
2801 static const char* msg = "Concurrent roots processing";
2802 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2803 EventMark em("%s", msg);
2804
2805 ShenandoahWorkerScope scope(workers(),
2806 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2807 "concurrent root processing");
2808
2809 try_inject_alloc_failure();
2810 op_roots();
2811 }
2812
2813 void ShenandoahHeap::entry_cleanup() {
2814 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup);
2815
2816 static const char* msg = "Concurrent cleanup";
2817 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2818 EventMark em("%s", msg);
2819
2820 // This phase does not use workers, no need for setup
2821
2822 try_inject_alloc_failure();
2823 op_cleanup();
2824 }
2825
2826 void ShenandoahHeap::entry_reset() {
2827 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset);
2828
2829 static const char* msg = "Concurrent reset";
2830 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2831 EventMark em("%s", msg);
2832
2833 ShenandoahWorkerScope scope(workers(),
2834 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2835 "concurrent reset");
2836
2837 try_inject_alloc_failure();
2838 op_reset();
2839 }
2840
2841 void ShenandoahHeap::entry_preclean() {
2842 if (ShenandoahPreclean && process_references()) {
2843 static const char* msg = "Concurrent precleaning";
2844 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2845 EventMark em("%s", msg);
2846
2847 ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
2848
2849 ShenandoahWorkerScope scope(workers(),
2850 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2851 "concurrent preclean",
2852 /* check_workers = */ false);
2853
2854 try_inject_alloc_failure();
2855 op_preclean();
2856 }
2857 }
2858
2859 void ShenandoahHeap::entry_traversal() {
2860 static const char* msg = "Concurrent traversal";
2861 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2862 EventMark em("%s", msg);
2863
2864 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2865
2866 ShenandoahWorkerScope scope(workers(),
2867 ShenandoahWorkerPolicy::calc_workers_for_conc_traversal(),
2868 "concurrent traversal");
2869
2870 try_inject_alloc_failure();
2871 op_traversal();
2872 }
2873
2874 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2875 static const char *msg = "Concurrent uncommit";
2876 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2877 EventMark em("%s", msg);
2878
2879 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit);
2880
2881 op_uncommit(shrink_before);
2882 }
2883
2884 void ShenandoahHeap::try_inject_alloc_failure() {
2885 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2886 _inject_alloc_failure.set();
2887 os::naked_short_sleep(1);
2888 if (cancelled_gc()) {
2889 log_info(gc)("Allocation failure was successfully injected");
2890 }
2891 }
2892 }
2893
2894 bool ShenandoahHeap::should_inject_alloc_failure() {
2895 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2896 }
2897
2898 void ShenandoahHeap::initialize_serviceability() {
2899 _memory_pool = new ShenandoahMemoryPool(this);
2900 _cycle_memory_manager.add_pool(_memory_pool);
2901 _stw_memory_manager.add_pool(_memory_pool);
2902 }
2903
2904 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2905 GrowableArray<GCMemoryManager*> memory_managers(2);
2906 memory_managers.append(&_cycle_memory_manager);
2907 memory_managers.append(&_stw_memory_manager);
2908 return memory_managers;
2909 }
2910
2911 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2912 GrowableArray<MemoryPool*> memory_pools(1);
2913 memory_pools.append(_memory_pool);
2914 return memory_pools;
2915 }
2916
2917 MemoryUsage ShenandoahHeap::memory_usage() {
2918 return _memory_pool->get_memory_usage();
2919 }
2920
2921 void ShenandoahHeap::enter_evacuation() {
2922 _oom_evac_handler.enter_evacuation();
2923 }
2924
2925 void ShenandoahHeap::leave_evacuation() {
2926 _oom_evac_handler.leave_evacuation();
2927 }
2928
2929 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2930 _heap(ShenandoahHeap::heap()),
2931 _index(0) {}
2932
2933 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2934 _heap(heap),
2935 _index(0) {}
2936
2937 void ShenandoahRegionIterator::reset() {
2938 _index = 0;
2939 }
2940
2941 bool ShenandoahRegionIterator::has_next() const {
2942 return _index < _heap->num_regions();
2943 }
2944
2945 char ShenandoahHeap::gc_state() const {
2946 return _gc_state.raw_value();
2947 }
2948
2949 void ShenandoahHeap::deduplicate_string(oop str) {
2950 assert(java_lang_String::is_instance(str), "invariant");
2951
2952 if (ShenandoahStringDedup::is_enabled()) {
2953 ShenandoahStringDedup::deduplicate(str);
2954 }
2955 }
2956
2957 const char* ShenandoahHeap::init_mark_event_message() const {
2958 bool update_refs = has_forwarded_objects();
2959 bool proc_refs = process_references();
2960 bool unload_cls = unload_classes();
2961
2962 if (update_refs && proc_refs && unload_cls) {
2963 return "Pause Init Mark (update refs) (process weakrefs) (unload classes)";
2964 } else if (update_refs && proc_refs) {
2965 return "Pause Init Mark (update refs) (process weakrefs)";
2966 } else if (update_refs && unload_cls) {
2967 return "Pause Init Mark (update refs) (unload classes)";
2968 } else if (proc_refs && unload_cls) {
2969 return "Pause Init Mark (process weakrefs) (unload classes)";
2970 } else if (update_refs) {
2971 return "Pause Init Mark (update refs)";
2972 } else if (proc_refs) {
2973 return "Pause Init Mark (process weakrefs)";
2974 } else if (unload_cls) {
2975 return "Pause Init Mark (unload classes)";
2976 } else {
2977 return "Pause Init Mark";
2978 }
2979 }
2980
2981 const char* ShenandoahHeap::final_mark_event_message() const {
2982 bool update_refs = has_forwarded_objects();
2983 bool proc_refs = process_references();
2984 bool unload_cls = unload_classes();
2985
2986 if (update_refs && proc_refs && unload_cls) {
2987 return "Pause Final Mark (update refs) (process weakrefs) (unload classes)";
2988 } else if (update_refs && proc_refs) {
2989 return "Pause Final Mark (update refs) (process weakrefs)";
2990 } else if (update_refs && unload_cls) {
2991 return "Pause Final Mark (update refs) (unload classes)";
2992 } else if (proc_refs && unload_cls) {
2993 return "Pause Final Mark (process weakrefs) (unload classes)";
2994 } else if (update_refs) {
2995 return "Pause Final Mark (update refs)";
2996 } else if (proc_refs) {
2997 return "Pause Final Mark (process weakrefs)";
2998 } else if (unload_cls) {
2999 return "Pause Final Mark (unload classes)";
3000 } else {
3001 return "Pause Final Mark";
3002 }
3003 }
3004
3005 const char* ShenandoahHeap::conc_mark_event_message() const {
3006 bool update_refs = has_forwarded_objects();
3007 bool proc_refs = process_references();
3008 bool unload_cls = unload_classes();
3009
3010 if (update_refs && proc_refs && unload_cls) {
3011 return "Concurrent marking (update refs) (process weakrefs) (unload classes)";
3012 } else if (update_refs && proc_refs) {
3013 return "Concurrent marking (update refs) (process weakrefs)";
3014 } else if (update_refs && unload_cls) {
3015 return "Concurrent marking (update refs) (unload classes)";
3016 } else if (proc_refs && unload_cls) {
3017 return "Concurrent marking (process weakrefs) (unload classes)";
3018 } else if (update_refs) {
3019 return "Concurrent marking (update refs)";
3020 } else if (proc_refs) {
3021 return "Concurrent marking (process weakrefs)";
3022 } else if (unload_cls) {
3023 return "Concurrent marking (unload classes)";
3024 } else {
3025 return "Concurrent marking";
3026 }
3027 }
3028
3029 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
3030 switch (point) {
3031 case _degenerated_unset:
3032 return "Pause Degenerated GC (<UNSET>)";
3033 case _degenerated_traversal:
3034 return "Pause Degenerated GC (Traversal)";
3035 case _degenerated_outside_cycle:
3036 return "Pause Degenerated GC (Outside of Cycle)";
3037 case _degenerated_mark:
3038 return "Pause Degenerated GC (Mark)";
3039 case _degenerated_evac:
3040 return "Pause Degenerated GC (Evacuation)";
3041 case _degenerated_updaterefs:
3042 return "Pause Degenerated GC (Update Refs)";
3043 default:
3044 ShouldNotReachHere();
3045 return "ERROR";
3046 }
3047 }
3048
3049 jushort* ShenandoahHeap::get_liveness_cache(uint worker_id) {
3050 #ifdef ASSERT
3051 assert(_liveness_cache != NULL, "sanity");
3052 assert(worker_id < _max_workers, "sanity");
3053 for (uint i = 0; i < num_regions(); i++) {
3054 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
3055 }
3056 #endif
3057 return _liveness_cache[worker_id];
3058 }
3059
3060 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
3061 assert(worker_id < _max_workers, "sanity");
3062 assert(_liveness_cache != NULL, "sanity");
3063 jushort* ld = _liveness_cache[worker_id];
3064 for (uint i = 0; i < num_regions(); i++) {
3065 ShenandoahHeapRegion* r = get_region(i);
3066 jushort live = ld[i];
3067 if (live > 0) {
3068 r->increase_live_data_gc_words(live);
3069 ld[i] = 0;
3070 }
3071 }
3072 }