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