1 /*
2 * Copyright (c) 2013, 2020, Red Hat, Inc. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.hpp"
27 #include "memory/universe.hpp"
28
29 #include "gc/shared/gcArguments.hpp"
30 #include "gc/shared/gcTimer.hpp"
31 #include "gc/shared/gcTraceTime.inline.hpp"
32 #include "gc/shared/locationPrinter.inline.hpp"
33 #include "gc/shared/memAllocator.hpp"
34 #include "gc/shared/oopStorageSet.hpp"
35 #include "gc/shared/plab.hpp"
36
37 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
38 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
39 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
40 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
41 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
42 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
43 #include "gc/shenandoah/shenandoahControlThread.hpp"
44 #include "gc/shenandoah/shenandoahFreeSet.hpp"
45 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
46 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
47 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
48 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
49 #include "gc/shenandoah/shenandoahInitLogger.hpp"
50 #include "gc/shenandoah/shenandoahMarkCompact.hpp"
51 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
52 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
53 #include "gc/shenandoah/shenandoahMetrics.hpp"
54 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
55 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
56 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
57 #include "gc/shenandoah/shenandoahPadding.hpp"
58 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
59 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
60 #include "gc/shenandoah/shenandoahStringDedup.hpp"
61 #include "gc/shenandoah/shenandoahTaskqueue.hpp"
62 #include "gc/shenandoah/shenandoahUtils.hpp"
63 #include "gc/shenandoah/shenandoahVerifier.hpp"
64 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
65 #include "gc/shenandoah/shenandoahVMOperations.hpp"
66 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
67 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
68 #include "gc/shenandoah/mode/shenandoahIUMode.hpp"
69 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
70 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
71 #if INCLUDE_JFR
72 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
73 #endif
74
75 #include "memory/metaspace.hpp"
76 #include "oops/compressedOops.inline.hpp"
77 #include "runtime/atomic.hpp"
78 #include "runtime/globals.hpp"
79 #include "runtime/interfaceSupport.inline.hpp"
80 #include "runtime/orderAccess.hpp"
81 #include "runtime/safepointMechanism.hpp"
82 #include "runtime/vmThread.hpp"
83 #include "services/mallocTracker.hpp"
84 #include "utilities/powerOfTwo.hpp"
85
86 ShenandoahHeap* ShenandoahHeap::_heap = NULL;
87
88 #ifdef ASSERT
89 template <class T>
90 void ShenandoahAssertToSpaceClosure::do_oop_work(T* p) {
91 T o = RawAccess<>::oop_load(p);
92 if (! CompressedOops::is_null(o)) {
93 oop obj = CompressedOops::decode_not_null(o);
94 shenandoah_assert_not_forwarded(p, obj);
95 }
96 }
97
98 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_work(p); }
99 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_work(p); }
100 #endif
101
102 class ShenandoahPretouchHeapTask : public AbstractGangTask {
103 private:
104 ShenandoahRegionIterator _regions;
105 const size_t _page_size;
106 public:
107 ShenandoahPretouchHeapTask(size_t page_size) :
108 AbstractGangTask("Shenandoah Pretouch Heap"),
109 _page_size(page_size) {}
110
111 virtual void work(uint worker_id) {
112 ShenandoahHeapRegion* r = _regions.next();
113 while (r != NULL) {
114 if (r->is_committed()) {
115 os::pretouch_memory(r->bottom(), r->end(), _page_size);
116 }
117 r = _regions.next();
118 }
119 }
120 };
121
122 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
123 private:
124 ShenandoahRegionIterator _regions;
125 char* _bitmap_base;
126 const size_t _bitmap_size;
127 const size_t _page_size;
128 public:
129 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
130 AbstractGangTask("Shenandoah Pretouch Bitmap"),
131 _bitmap_base(bitmap_base),
132 _bitmap_size(bitmap_size),
133 _page_size(page_size) {}
134
135 virtual void work(uint worker_id) {
136 ShenandoahHeapRegion* r = _regions.next();
137 while (r != NULL) {
138 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
139 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
140 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
141
142 if (r->is_committed()) {
143 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
144 }
145
146 r = _regions.next();
147 }
148 }
149 };
150
151 jint ShenandoahHeap::initialize() {
152 //
153 // Figure out heap sizing
154 //
155
156 size_t init_byte_size = InitialHeapSize;
157 size_t min_byte_size = MinHeapSize;
158 size_t max_byte_size = MaxHeapSize;
159 size_t heap_alignment = HeapAlignment;
160
161 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
162
163 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
164 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
165
166 _num_regions = ShenandoahHeapRegion::region_count();
167
168 // Now we know the number of regions, initialize the heuristics.
169 initialize_heuristics();
170
171 size_t num_committed_regions = init_byte_size / reg_size_bytes;
172 num_committed_regions = MIN2(num_committed_regions, _num_regions);
173 assert(num_committed_regions <= _num_regions, "sanity");
174 _initial_size = num_committed_regions * reg_size_bytes;
175
176 size_t num_min_regions = min_byte_size / reg_size_bytes;
177 num_min_regions = MIN2(num_min_regions, _num_regions);
178 assert(num_min_regions <= _num_regions, "sanity");
179 _minimum_size = num_min_regions * reg_size_bytes;
180
181 _committed = _initial_size;
182
183 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
184 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
185 size_t region_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
186
187 //
188 // Reserve and commit memory for heap
189 //
190
191 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
192 initialize_reserved_region(heap_rs);
193 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
194 _heap_region_special = heap_rs.special();
195
196 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
197 "Misaligned heap: " PTR_FORMAT, p2i(base()));
198
199 #if SHENANDOAH_OPTIMIZED_OBJTASK
200 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
201 // Fail if we ever attempt to address more than we can.
202 if ((uintptr_t)heap_rs.end() >= ObjArrayChunkedTask::max_addressable()) {
203 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
204 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
205 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
206 p2i(heap_rs.base()), p2i(heap_rs.end()), ObjArrayChunkedTask::max_addressable());
207 vm_exit_during_initialization("Fatal Error", buf);
208 }
209 #endif
210
211 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
212 if (!_heap_region_special) {
213 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
214 "Cannot commit heap memory");
215 }
216
217 //
218 // Reserve and commit memory for bitmap(s)
219 //
220
221 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
222 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
223
224 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
225
226 guarantee(bitmap_bytes_per_region != 0,
227 "Bitmap bytes per region should not be zero");
228 guarantee(is_power_of_2(bitmap_bytes_per_region),
229 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
230
231 if (bitmap_page_size > bitmap_bytes_per_region) {
232 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
233 _bitmap_bytes_per_slice = bitmap_page_size;
234 } else {
235 _bitmap_regions_per_slice = 1;
236 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
237 }
238
239 guarantee(_bitmap_regions_per_slice >= 1,
240 "Should have at least one region per slice: " SIZE_FORMAT,
241 _bitmap_regions_per_slice);
242
243 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
244 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
245 _bitmap_bytes_per_slice, bitmap_page_size);
246
247 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
248 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
249 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
250 _bitmap_region_special = bitmap.special();
251
252 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
253 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
254 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
255 if (!_bitmap_region_special) {
256 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
257 "Cannot commit bitmap memory");
258 }
259
260 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
261
262 if (ShenandoahVerify) {
263 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
264 if (!verify_bitmap.special()) {
265 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
266 "Cannot commit verification bitmap memory");
267 }
268 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
269 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
270 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
271 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
272 }
273
274 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
275 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
276 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
277 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
278 _aux_bitmap_region_special = aux_bitmap.special();
279 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
280
281 //
282 // Create regions and region sets
283 //
284 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
285 size_t region_storage_size = align_up(region_align * _num_regions, region_page_size);
286 region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity());
287
288 ReservedSpace region_storage(region_storage_size, region_page_size);
289 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
290 if (!region_storage.special()) {
291 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
292 "Cannot commit region memory");
293 }
294
295 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks.
296 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there.
297 // If not successful, bite a bullet and allocate at whatever address.
298 {
299 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
300 size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align);
301
302 uintptr_t min = round_up_power_of_2(cset_align);
303 uintptr_t max = (1u << 30u);
304
305 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
306 char* req_addr = (char*)addr;
307 assert(is_aligned(req_addr, cset_align), "Should be aligned");
308 ReservedSpace cset_rs(cset_size, cset_align, false, req_addr);
309 if (cset_rs.is_reserved()) {
310 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr);
311 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
312 break;
313 }
314 }
315
316 if (_collection_set == NULL) {
317 ReservedSpace cset_rs(cset_size, cset_align, false);
318 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
319 }
320 }
321
322 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
323 _free_set = new ShenandoahFreeSet(this, _num_regions);
324
325 {
326 ShenandoahHeapLocker locker(lock());
327
328 for (size_t i = 0; i < _num_regions; i++) {
329 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
330 bool is_committed = i < num_committed_regions;
331 void* loc = region_storage.base() + i * region_align;
332
333 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
334 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
335
336 _marking_context->initialize_top_at_mark_start(r);
337 _regions[i] = r;
338 assert(!collection_set()->is_in(i), "New region should not be in collection set");
339 }
340
341 // Initialize to complete
342 _marking_context->mark_complete();
343
344 _free_set->rebuild();
345 }
346
347 if (AlwaysPreTouch) {
348 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
349 // before initialize() below zeroes it with initializing thread. For any given region,
350 // we touch the region and the corresponding bitmaps from the same thread.
351 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
352
353 _pretouch_heap_page_size = heap_page_size;
354 _pretouch_bitmap_page_size = bitmap_page_size;
355
356 #ifdef LINUX
357 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
358 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
359 // them into huge one. Therefore, we need to pretouch with smaller pages.
360 if (UseTransparentHugePages) {
361 _pretouch_heap_page_size = (size_t)os::vm_page_size();
362 _pretouch_bitmap_page_size = (size_t)os::vm_page_size();
363 }
364 #endif
365
366 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
367 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
368
369 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size);
370 _workers->run_task(&bcl);
371
372 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size);
373 _workers->run_task(&hcl);
374 }
375
376 //
377 // Initialize the rest of GC subsystems
378 //
379
380 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
381 for (uint worker = 0; worker < _max_workers; worker++) {
382 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
383 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
384 }
385
386 // There should probably be Shenandoah-specific options for these,
387 // just as there are G1-specific options.
388 {
389 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
390 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
391 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
392 }
393
394 _monitoring_support = new ShenandoahMonitoringSupport(this);
395 _phase_timings = new ShenandoahPhaseTimings(max_workers());
396 ShenandoahStringDedup::initialize();
397 ShenandoahCodeRoots::initialize();
398
399 if (ShenandoahPacing) {
400 _pacer = new ShenandoahPacer(this);
401 _pacer->setup_for_idle();
402 } else {
403 _pacer = NULL;
404 }
405
406 _control_thread = new ShenandoahControlThread();
407
408 _ref_proc_mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
409 _ref_proc_mt_discovery = _max_workers > 1;
410
411 ShenandoahInitLogger::print();
412
413 return JNI_OK;
414 }
415
416 void ShenandoahHeap::initialize_heuristics() {
417 if (ShenandoahGCMode != NULL) {
418 if (strcmp(ShenandoahGCMode, "satb") == 0) {
419 _gc_mode = new ShenandoahSATBMode();
420 } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
421 _gc_mode = new ShenandoahIUMode();
422 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
423 _gc_mode = new ShenandoahPassiveMode();
424 } else {
425 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
426 }
427 } else {
428 ShouldNotReachHere();
429 }
430 _gc_mode->initialize_flags();
431 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
432 vm_exit_during_initialization(
433 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
434 _gc_mode->name()));
435 }
436 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
437 vm_exit_during_initialization(
438 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
439 _gc_mode->name()));
440 }
441
442 _heuristics = _gc_mode->initialize_heuristics();
443
444 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
445 vm_exit_during_initialization(
446 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
447 _heuristics->name()));
448 }
449 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
450 vm_exit_during_initialization(
451 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
452 _heuristics->name()));
453 }
454 }
455
456 #ifdef _MSC_VER
457 #pragma warning( push )
458 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
459 #endif
460
461 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
462 CollectedHeap(),
463 _initial_size(0),
464 _used(0),
465 _committed(0),
466 _bytes_allocated_since_gc_start(0),
467 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
468 _workers(NULL),
469 _safepoint_workers(NULL),
470 _heap_region_special(false),
471 _num_regions(0),
472 _regions(NULL),
473 _update_refs_iterator(this),
474 _control_thread(NULL),
475 _shenandoah_policy(policy),
476 _heuristics(NULL),
477 _free_set(NULL),
478 _scm(new ShenandoahConcurrentMark()),
479 _full_gc(new ShenandoahMarkCompact()),
480 _pacer(NULL),
481 _verifier(NULL),
482 _phase_timings(NULL),
483 _monitoring_support(NULL),
484 _memory_pool(NULL),
485 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
486 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
487 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
488 _soft_ref_policy(),
489 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
490 _ref_processor(NULL),
491 _marking_context(NULL),
492 _bitmap_size(0),
493 _bitmap_regions_per_slice(0),
494 _bitmap_bytes_per_slice(0),
495 _bitmap_region_special(false),
496 _aux_bitmap_region_special(false),
497 _liveness_cache(NULL),
498 _collection_set(NULL)
499 {
500 _heap = this;
501
502 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
503
504 _max_workers = MAX2(_max_workers, 1U);
505 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
506 /* are_GC_task_threads */ true,
507 /* are_ConcurrentGC_threads */ true);
508 if (_workers == NULL) {
509 vm_exit_during_initialization("Failed necessary allocation.");
510 } else {
511 _workers->initialize_workers();
512 }
513
514 if (ParallelGCThreads > 1) {
515 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
516 ParallelGCThreads,
517 /* are_GC_task_threads */ false,
518 /* are_ConcurrentGC_threads */ false);
519 _safepoint_workers->initialize_workers();
520 }
521 }
522
523 #ifdef _MSC_VER
524 #pragma warning( pop )
525 #endif
526
527 class ShenandoahResetBitmapTask : public AbstractGangTask {
528 private:
529 ShenandoahRegionIterator _regions;
530
531 public:
532 ShenandoahResetBitmapTask() :
533 AbstractGangTask("Parallel Reset Bitmap Task") {}
534
535 void work(uint worker_id) {
536 ShenandoahHeapRegion* region = _regions.next();
537 ShenandoahHeap* heap = ShenandoahHeap::heap();
538 ShenandoahMarkingContext* const ctx = heap->marking_context();
539 while (region != NULL) {
540 if (heap->is_bitmap_slice_committed(region)) {
541 ctx->clear_bitmap(region);
542 }
543 region = _regions.next();
544 }
545 }
546 };
547
548 void ShenandoahHeap::reset_mark_bitmap() {
549 assert_gc_workers(_workers->active_workers());
550 mark_incomplete_marking_context();
551
552 ShenandoahResetBitmapTask task;
553 _workers->run_task(&task);
554 }
555
556 void ShenandoahHeap::print_on(outputStream* st) const {
557 st->print_cr("Shenandoah Heap");
558 st->print_cr(" " SIZE_FORMAT "%s total, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
559 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
560 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
561 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
562 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
563 num_regions(),
564 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
565 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
566
567 st->print("Status: ");
568 if (has_forwarded_objects()) st->print("has forwarded objects, ");
569 if (is_concurrent_mark_in_progress()) st->print("marking, ");
570 if (is_evacuation_in_progress()) st->print("evacuating, ");
571 if (is_update_refs_in_progress()) st->print("updating refs, ");
572 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
573 if (is_full_gc_in_progress()) st->print("full gc, ");
574 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
575 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
576 if (is_concurrent_strong_root_in_progress() &&
577 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
578
579 if (cancelled_gc()) {
580 st->print("cancelled");
581 } else {
582 st->print("not cancelled");
583 }
584 st->cr();
585
586 st->print_cr("Reserved region:");
587 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
588 p2i(reserved_region().start()),
589 p2i(reserved_region().end()));
590
591 ShenandoahCollectionSet* cset = collection_set();
592 st->print_cr("Collection set:");
593 if (cset != NULL) {
594 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
595 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
596 } else {
597 st->print_cr(" (NULL)");
598 }
599
600 st->cr();
601 MetaspaceUtils::print_on(st);
602
603 if (Verbose) {
604 print_heap_regions_on(st);
605 }
606 }
607
608 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
609 public:
610 void do_thread(Thread* thread) {
611 assert(thread != NULL, "Sanity");
612 assert(thread->is_Worker_thread(), "Only worker thread expected");
613 ShenandoahThreadLocalData::initialize_gclab(thread);
614 }
615 };
616
617 void ShenandoahHeap::post_initialize() {
618 CollectedHeap::post_initialize();
619 MutexLocker ml(Threads_lock);
620
621 ShenandoahInitWorkerGCLABClosure init_gclabs;
622 _workers->threads_do(&init_gclabs);
623
624 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
625 // Now, we will let WorkGang to initialize gclab when new worker is created.
626 _workers->set_initialize_gclab();
627
628 _scm->initialize(_max_workers);
629 _full_gc->initialize(_gc_timer);
630
631 ref_processing_init();
632
633 _heuristics->initialize();
634
635 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
636 }
637
638 size_t ShenandoahHeap::used() const {
639 return Atomic::load_acquire(&_used);
640 }
641
642 size_t ShenandoahHeap::committed() const {
643 OrderAccess::acquire();
644 return _committed;
645 }
646
647 void ShenandoahHeap::increase_committed(size_t bytes) {
648 shenandoah_assert_heaplocked_or_safepoint();
649 _committed += bytes;
650 }
651
652 void ShenandoahHeap::decrease_committed(size_t bytes) {
653 shenandoah_assert_heaplocked_or_safepoint();
654 _committed -= bytes;
655 }
656
657 void ShenandoahHeap::increase_used(size_t bytes) {
658 Atomic::add(&_used, bytes);
659 }
660
661 void ShenandoahHeap::set_used(size_t bytes) {
662 Atomic::release_store_fence(&_used, bytes);
663 }
664
665 void ShenandoahHeap::decrease_used(size_t bytes) {
666 assert(used() >= bytes, "never decrease heap size by more than we've left");
667 Atomic::sub(&_used, bytes);
668 }
669
670 void ShenandoahHeap::increase_allocated(size_t bytes) {
671 Atomic::add(&_bytes_allocated_since_gc_start, bytes);
672 }
673
674 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
675 size_t bytes = words * HeapWordSize;
676 if (!waste) {
677 increase_used(bytes);
678 }
679 increase_allocated(bytes);
680 if (ShenandoahPacing) {
681 control_thread()->pacing_notify_alloc(words);
682 if (waste) {
683 pacer()->claim_for_alloc(words, true);
684 }
685 }
686 }
687
688 size_t ShenandoahHeap::capacity() const {
689 return committed();
690 }
691
692 size_t ShenandoahHeap::max_capacity() const {
693 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
694 }
695
696 size_t ShenandoahHeap::min_capacity() const {
697 return _minimum_size;
698 }
699
700 size_t ShenandoahHeap::initial_capacity() const {
701 return _initial_size;
702 }
703
704 bool ShenandoahHeap::is_in(const void* p) const {
705 HeapWord* heap_base = (HeapWord*) base();
706 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
707 return p >= heap_base && p < last_region_end;
708 }
709
710 void ShenandoahHeap::op_uncommit(double shrink_before) {
711 assert (ShenandoahUncommit, "should be enabled");
712
713 // Application allocates from the beginning of the heap, and GC allocates at
714 // the end of it. It is more efficient to uncommit from the end, so that applications
715 // could enjoy the near committed regions. GC allocations are much less frequent,
716 // and therefore can accept the committing costs.
717
718 size_t count = 0;
719 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
720 ShenandoahHeapRegion* r = get_region(i - 1);
721 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
722 ShenandoahHeapLocker locker(lock());
723 if (r->is_empty_committed()) {
724 // Do not uncommit below minimal capacity
725 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
726 break;
727 }
728
729 r->make_uncommitted();
730 count++;
731 }
732 }
733 SpinPause(); // allow allocators to take the lock
734 }
735
736 if (count > 0) {
737 control_thread()->notify_heap_changed();
738 }
739 }
740
741 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
742 // New object should fit the GCLAB size
743 size_t min_size = MAX2(size, PLAB::min_size());
744
745 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
746 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
747 new_size = MIN2(new_size, PLAB::max_size());
748 new_size = MAX2(new_size, PLAB::min_size());
749
750 // Record new heuristic value even if we take any shortcut. This captures
751 // the case when moderately-sized objects always take a shortcut. At some point,
752 // heuristics should catch up with them.
753 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
754
755 if (new_size < size) {
756 // New size still does not fit the object. Fall back to shared allocation.
757 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
758 return NULL;
759 }
760
761 // Retire current GCLAB, and allocate a new one.
762 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
763 gclab->retire();
764
765 size_t actual_size = 0;
766 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
767 if (gclab_buf == NULL) {
768 return NULL;
769 }
770
771 assert (size <= actual_size, "allocation should fit");
772
773 if (ZeroTLAB) {
774 // ..and clear it.
775 Copy::zero_to_words(gclab_buf, actual_size);
776 } else {
777 // ...and zap just allocated object.
778 #ifdef ASSERT
779 // Skip mangling the space corresponding to the object header to
780 // ensure that the returned space is not considered parsable by
781 // any concurrent GC thread.
782 size_t hdr_size = oopDesc::header_size();
783 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
784 #endif // ASSERT
785 }
786 gclab->set_buf(gclab_buf, actual_size);
787 return gclab->allocate(size);
788 }
789
790 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
791 size_t requested_size,
792 size_t* actual_size) {
793 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
794 HeapWord* res = allocate_memory(req);
795 if (res != NULL) {
796 *actual_size = req.actual_size();
797 } else {
798 *actual_size = 0;
799 }
800 return res;
801 }
802
803 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
804 size_t word_size,
805 size_t* actual_size) {
806 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
807 HeapWord* res = allocate_memory(req);
808 if (res != NULL) {
809 *actual_size = req.actual_size();
810 } else {
811 *actual_size = 0;
812 }
813 return res;
814 }
815
816 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
817 intptr_t pacer_epoch = 0;
818 bool in_new_region = false;
819 HeapWord* result = NULL;
820
821 if (req.is_mutator_alloc()) {
822 if (ShenandoahPacing) {
823 pacer()->pace_for_alloc(req.size());
824 pacer_epoch = pacer()->epoch();
825 }
826
827 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
828 result = allocate_memory_under_lock(req, in_new_region);
829 }
830
831 // Allocation failed, block until control thread reacted, then retry allocation.
832 //
833 // It might happen that one of the threads requesting allocation would unblock
834 // way later after GC happened, only to fail the second allocation, because
835 // other threads have already depleted the free storage. In this case, a better
836 // strategy is to try again, as long as GC makes progress.
837 //
838 // Then, we need to make sure the allocation was retried after at least one
839 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
840
841 size_t tries = 0;
842
843 while (result == NULL && _progress_last_gc.is_set()) {
844 tries++;
845 control_thread()->handle_alloc_failure(req);
846 result = allocate_memory_under_lock(req, in_new_region);
847 }
848
849 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
850 tries++;
851 control_thread()->handle_alloc_failure(req);
852 result = allocate_memory_under_lock(req, in_new_region);
853 }
854
855 } else {
856 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
857 result = allocate_memory_under_lock(req, in_new_region);
858 // Do not call handle_alloc_failure() here, because we cannot block.
859 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
860 }
861
862 if (in_new_region) {
863 control_thread()->notify_heap_changed();
864 }
865
866 if (result != NULL) {
867 size_t requested = req.size();
868 size_t actual = req.actual_size();
869
870 assert (req.is_lab_alloc() || (requested == actual),
871 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
872 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
873
874 if (req.is_mutator_alloc()) {
875 notify_mutator_alloc_words(actual, false);
876
877 // If we requested more than we were granted, give the rest back to pacer.
878 // This only matters if we are in the same pacing epoch: do not try to unpace
879 // over the budget for the other phase.
880 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
881 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
882 }
883 } else {
884 increase_used(actual*HeapWordSize);
885 }
886 }
887
888 return result;
889 }
890
891 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
892 ShenandoahHeapLocker locker(lock());
893 return _free_set->allocate(req, in_new_region);
894 }
895
896 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
897 bool* gc_overhead_limit_was_exceeded) {
898 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
899 return allocate_memory(req);
900 }
901
902 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
903 size_t size,
904 Metaspace::MetadataType mdtype) {
905 MetaWord* result;
906
907 // Inform metaspace OOM to GC heuristics if class unloading is possible.
908 if (heuristics()->can_unload_classes()) {
909 ShenandoahHeuristics* h = heuristics();
910 h->record_metaspace_oom();
911 }
912
913 // Expand and retry allocation
914 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
915 if (result != NULL) {
916 return result;
917 }
918
919 // Start full GC
920 collect(GCCause::_metadata_GC_clear_soft_refs);
921
922 // Retry allocation
923 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
924 if (result != NULL) {
925 return result;
926 }
927
928 // Expand and retry allocation
929 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
930 if (result != NULL) {
931 return result;
932 }
933
934 // Out of memory
935 return NULL;
936 }
937
938 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
939 private:
940 ShenandoahHeap* const _heap;
941 Thread* const _thread;
942 public:
943 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
944 _heap(heap), _thread(Thread::current()) {}
945
946 void do_object(oop p) {
947 shenandoah_assert_marked(NULL, p);
948 if (!p->is_forwarded()) {
949 _heap->evacuate_object(p, _thread);
950 }
951 }
952 };
953
954 class ShenandoahEvacuationTask : public AbstractGangTask {
955 private:
956 ShenandoahHeap* const _sh;
957 ShenandoahCollectionSet* const _cs;
958 bool _concurrent;
959 public:
960 ShenandoahEvacuationTask(ShenandoahHeap* sh,
961 ShenandoahCollectionSet* cs,
962 bool concurrent) :
963 AbstractGangTask("Parallel Evacuation Task"),
964 _sh(sh),
965 _cs(cs),
966 _concurrent(concurrent)
967 {}
968
969 void work(uint worker_id) {
970 if (_concurrent) {
971 ShenandoahConcurrentWorkerSession worker_session(worker_id);
972 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
973 ShenandoahEvacOOMScope oom_evac_scope;
974 do_work();
975 } else {
976 ShenandoahParallelWorkerSession worker_session(worker_id);
977 ShenandoahEvacOOMScope oom_evac_scope;
978 do_work();
979 }
980 }
981
982 private:
983 void do_work() {
984 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
985 ShenandoahHeapRegion* r;
986 while ((r =_cs->claim_next()) != NULL) {
987 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
988 _sh->marked_object_iterate(r, &cl);
989
990 if (ShenandoahPacing) {
991 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
992 }
993
994 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
995 break;
996 }
997 }
998 }
999 };
1000
1001 void ShenandoahHeap::trash_cset_regions() {
1002 ShenandoahHeapLocker locker(lock());
1003
1004 ShenandoahCollectionSet* set = collection_set();
1005 ShenandoahHeapRegion* r;
1006 set->clear_current_index();
1007 while ((r = set->next()) != NULL) {
1008 r->make_trash();
1009 }
1010 collection_set()->clear();
1011 }
1012
1013 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1014 st->print_cr("Heap Regions:");
1015 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
1016 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
1017 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark");
1018 st->print_cr("SN=alloc sequence number");
1019
1020 for (size_t i = 0; i < num_regions(); i++) {
1021 get_region(i)->print_on(st);
1022 }
1023 }
1024
1025 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1026 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1027
1028 oop humongous_obj = oop(start->bottom());
1029 size_t size = humongous_obj->size();
1030 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1031 size_t index = start->index() + required_regions - 1;
1032
1033 assert(!start->has_live(), "liveness must be zero");
1034
1035 for(size_t i = 0; i < required_regions; i++) {
1036 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1037 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1038 ShenandoahHeapRegion* region = get_region(index --);
1039
1040 assert(region->is_humongous(), "expect correct humongous start or continuation");
1041 assert(!region->is_cset(), "Humongous region should not be in collection set");
1042
1043 region->make_trash_immediate();
1044 }
1045 }
1046
1047 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1048 public:
1049 ShenandoahCheckCleanGCLABClosure() {}
1050 void do_thread(Thread* thread) {
1051 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1052 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1053 assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1054 }
1055 };
1056
1057 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1058 private:
1059 bool const _resize;
1060 public:
1061 ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1062 void do_thread(Thread* thread) {
1063 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1064 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1065 gclab->retire();
1066 if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1067 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1068 }
1069 }
1070 };
1071
1072 void ShenandoahHeap::labs_make_parsable() {
1073 assert(UseTLAB, "Only call with UseTLAB");
1074
1075 ShenandoahRetireGCLABClosure cl(false);
1076
1077 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1078 ThreadLocalAllocBuffer& tlab = t->tlab();
1079 tlab.make_parsable();
1080 cl.do_thread(t);
1081 }
1082
1083 workers()->threads_do(&cl);
1084 }
1085
1086 void ShenandoahHeap::tlabs_retire(bool resize) {
1087 assert(UseTLAB, "Only call with UseTLAB");
1088 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1089
1090 ThreadLocalAllocStats stats;
1091
1092 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1093 ThreadLocalAllocBuffer& tlab = t->tlab();
1094 tlab.retire(&stats);
1095 if (resize) {
1096 tlab.resize();
1097 }
1098 }
1099
1100 stats.publish();
1101
1102 #ifdef ASSERT
1103 ShenandoahCheckCleanGCLABClosure cl;
1104 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1105 cl.do_thread(t);
1106 }
1107 workers()->threads_do(&cl);
1108 #endif
1109 }
1110
1111 void ShenandoahHeap::gclabs_retire(bool resize) {
1112 assert(UseTLAB, "Only call with UseTLAB");
1113 assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1114
1115 ShenandoahRetireGCLABClosure cl(resize);
1116 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1117 cl.do_thread(t);
1118 }
1119 workers()->threads_do(&cl);
1120 }
1121
1122 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1123 private:
1124 ShenandoahRootEvacuator* _rp;
1125
1126 public:
1127 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1128 AbstractGangTask("Shenandoah evacuate and update roots"),
1129 _rp(rp) {}
1130
1131 void work(uint worker_id) {
1132 ShenandoahParallelWorkerSession worker_session(worker_id);
1133 ShenandoahEvacOOMScope oom_evac_scope;
1134 ShenandoahEvacuateUpdateRootsClosure<> cl;
1135 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1136 _rp->roots_do(worker_id, &cl);
1137 }
1138 };
1139
1140 void ShenandoahHeap::evacuate_and_update_roots() {
1141 #if COMPILER2_OR_JVMCI
1142 DerivedPointerTable::clear();
1143 #endif
1144 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1145 {
1146 // Include concurrent roots if current cycle can not process those roots concurrently
1147 ShenandoahRootEvacuator rp(workers()->active_workers(),
1148 ShenandoahPhaseTimings::init_evac,
1149 !ShenandoahConcurrentRoots::should_do_concurrent_roots(),
1150 !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
1151 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1152 workers()->run_task(&roots_task);
1153 }
1154
1155 #if COMPILER2_OR_JVMCI
1156 DerivedPointerTable::update_pointers();
1157 #endif
1158 }
1159
1160 // Returns size in bytes
1161 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1162 if (ShenandoahElasticTLAB) {
1163 // With Elastic TLABs, return the max allowed size, and let the allocation path
1164 // figure out the safe size for current allocation.
1165 return ShenandoahHeapRegion::max_tlab_size_bytes();
1166 } else {
1167 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1168 }
1169 }
1170
1171 size_t ShenandoahHeap::max_tlab_size() const {
1172 // Returns size in words
1173 return ShenandoahHeapRegion::max_tlab_size_words();
1174 }
1175
1176 void ShenandoahHeap::collect(GCCause::Cause cause) {
1177 control_thread()->request_gc(cause);
1178 }
1179
1180 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1181 //assert(false, "Shouldn't need to do full collections");
1182 }
1183
1184 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1185 ShenandoahHeapRegion* r = heap_region_containing(addr);
1186 if (r != NULL) {
1187 return r->block_start(addr);
1188 }
1189 return NULL;
1190 }
1191
1192 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1193 ShenandoahHeapRegion* r = heap_region_containing(addr);
1194 return r->block_is_obj(addr);
1195 }
1196
1197 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1198 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1199 }
1200
1201 jlong ShenandoahHeap::millis_since_last_gc() {
1202 double v = heuristics()->time_since_last_gc() * 1000;
1203 assert(0 <= v && v <= max_jlong, "value should fit: %f", v);
1204 return (jlong)v;
1205 }
1206
1207 void ShenandoahHeap::prepare_for_verify() {
1208 if (SafepointSynchronize::is_at_safepoint() && UseTLAB) {
1209 labs_make_parsable();
1210 }
1211 }
1212
1213 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1214 workers()->threads_do(tcl);
1215 if (_safepoint_workers != NULL) {
1216 _safepoint_workers->threads_do(tcl);
1217 }
1218 if (ShenandoahStringDedup::is_enabled()) {
1219 ShenandoahStringDedup::threads_do(tcl);
1220 }
1221 }
1222
1223 void ShenandoahHeap::print_tracing_info() const {
1224 LogTarget(Info, gc, stats) lt;
1225 if (lt.is_enabled()) {
1226 ResourceMark rm;
1227 LogStream ls(lt);
1228
1229 phase_timings()->print_global_on(&ls);
1230
1231 ls.cr();
1232 ls.cr();
1233
1234 shenandoah_policy()->print_gc_stats(&ls);
1235
1236 ls.cr();
1237 ls.cr();
1238
1239 if (ShenandoahPacing) {
1240 pacer()->print_on(&ls);
1241 }
1242
1243 ls.cr();
1244 ls.cr();
1245 }
1246 }
1247
1248 void ShenandoahHeap::verify(VerifyOption vo) {
1249 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1250 if (ShenandoahVerify) {
1251 verifier()->verify_generic(vo);
1252 } else {
1253 // TODO: Consider allocating verification bitmaps on demand,
1254 // and turn this on unconditionally.
1255 }
1256 }
1257 }
1258 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1259 return _free_set->capacity();
1260 }
1261
1262 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1263 private:
1264 MarkBitMap* _bitmap;
1265 Stack<oop,mtGC>* _oop_stack;
1266 ShenandoahHeap* const _heap;
1267 ShenandoahMarkingContext* const _marking_context;
1268
1269 template <class T>
1270 void do_oop_work(T* p) {
1271 T o = RawAccess<>::oop_load(p);
1272 if (!CompressedOops::is_null(o)) {
1273 oop obj = CompressedOops::decode_not_null(o);
1274 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1275 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1276 return;
1277 }
1278 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1279
1280 assert(oopDesc::is_oop(obj), "must be a valid oop");
1281 if (!_bitmap->is_marked(obj)) {
1282 _bitmap->mark(obj);
1283 _oop_stack->push(obj);
1284 }
1285 }
1286 }
1287 public:
1288 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1289 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1290 _marking_context(_heap->marking_context()) {}
1291 void do_oop(oop* p) { do_oop_work(p); }
1292 void do_oop(narrowOop* p) { do_oop_work(p); }
1293 };
1294
1295 /*
1296 * This is public API, used in preparation of object_iterate().
1297 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1298 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1299 * control, we call SH::tlabs_retire, SH::gclabs_retire.
1300 */
1301 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1302 // No-op.
1303 }
1304
1305 /*
1306 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1307 *
1308 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1309 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1310 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1311 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1312 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1313 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1314 * wiped the bitmap in preparation for next marking).
1315 *
1316 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1317 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1318 * is allowed to report dead objects, but is not required to do so.
1319 */
1320 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1321 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1322 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1323 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1324 return;
1325 }
1326
1327 // Reset bitmap
1328 _aux_bit_map.clear();
1329
1330 Stack<oop,mtGC> oop_stack;
1331
1332 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1333
1334 {
1335 // First, we process GC roots according to current GC cycle.
1336 // This populates the work stack with initial objects.
1337 // It is important to relinquish the associated locks before diving
1338 // into heap dumper.
1339 ShenandoahHeapIterationRootScanner rp;
1340 rp.roots_do(&oops);
1341 }
1342
1343 // Work through the oop stack to traverse heap.
1344 while (! oop_stack.is_empty()) {
1345 oop obj = oop_stack.pop();
1346 assert(oopDesc::is_oop(obj), "must be a valid oop");
1347 cl->do_object(obj);
1348 obj->oop_iterate(&oops);
1349 }
1350
1351 assert(oop_stack.is_empty(), "should be empty");
1352
1353 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1354 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1355 }
1356 }
1357
1358 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1359 void ShenandoahHeap::keep_alive(oop obj) {
1360 if (is_concurrent_mark_in_progress()) {
1361 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1362 }
1363 }
1364
1365 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1366 for (size_t i = 0; i < num_regions(); i++) {
1367 ShenandoahHeapRegion* current = get_region(i);
1368 blk->heap_region_do(current);
1369 }
1370 }
1371
1372 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1373 private:
1374 ShenandoahHeap* const _heap;
1375 ShenandoahHeapRegionClosure* const _blk;
1376
1377 shenandoah_padding(0);
1378 volatile size_t _index;
1379 shenandoah_padding(1);
1380
1381 public:
1382 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1383 AbstractGangTask("Parallel Region Task"),
1384 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1385
1386 void work(uint worker_id) {
1387 ShenandoahParallelWorkerSession worker_session(worker_id);
1388 size_t stride = ShenandoahParallelRegionStride;
1389
1390 size_t max = _heap->num_regions();
1391 while (_index < max) {
1392 size_t cur = Atomic::fetch_and_add(&_index, stride);
1393 size_t start = cur;
1394 size_t end = MIN2(cur + stride, max);
1395 if (start >= max) break;
1396
1397 for (size_t i = cur; i < end; i++) {
1398 ShenandoahHeapRegion* current = _heap->get_region(i);
1399 _blk->heap_region_do(current);
1400 }
1401 }
1402 }
1403 };
1404
1405 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1406 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1407 if (num_regions() > ShenandoahParallelRegionStride) {
1408 ShenandoahParallelHeapRegionTask task(blk);
1409 workers()->run_task(&task);
1410 } else {
1411 heap_region_iterate(blk);
1412 }
1413 }
1414
1415 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1416 private:
1417 ShenandoahMarkingContext* const _ctx;
1418 public:
1419 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1420
1421 void heap_region_do(ShenandoahHeapRegion* r) {
1422 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1423 if (r->is_active()) {
1424 // Check if region needs updating its TAMS. We have updated it already during concurrent
1425 // reset, so it is very likely we don't need to do another write here.
1426 if (_ctx->top_at_mark_start(r) != r->top()) {
1427 _ctx->capture_top_at_mark_start(r);
1428 }
1429 } else {
1430 assert(_ctx->top_at_mark_start(r) == r->top(),
1431 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1432 }
1433 }
1434
1435 bool is_thread_safe() { return true; }
1436 };
1437
1438 void ShenandoahHeap::op_init_mark() {
1439 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1440 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1441
1442 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1443 assert(!marking_context()->is_complete(), "should not be complete");
1444 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1445
1446 if (ShenandoahVerify) {
1447 verifier()->verify_before_concmark();
1448 }
1449
1450 if (VerifyBeforeGC) {
1451 Universe::verify();
1452 }
1453
1454 set_concurrent_mark_in_progress(true);
1455
1456 // We need to reset all TLABs because they might be below the TAMS, and we need to mark
1457 // the objects in them. Do not let mutators allocate any new objects in their current TLABs.
1458 // It is also a good place to resize the TLAB sizes for future allocations.
1459 if (UseTLAB) {
1460 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_manage_tlabs);
1461 tlabs_retire(ResizeTLAB);
1462 }
1463
1464 {
1465 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_region_states);
1466 ShenandoahInitMarkUpdateRegionStateClosure cl;
1467 parallel_heap_region_iterate(&cl);
1468 }
1469
1470 // Make above changes visible to worker threads
1471 OrderAccess::fence();
1472
1473 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1474
1475 if (ShenandoahPacing) {
1476 pacer()->setup_for_mark();
1477 }
1478
1479 // Arm nmethods for concurrent marking. When a nmethod is about to be executed,
1480 // we need to make sure that all its metadata are marked. alternative is to remark
1481 // thread roots at final mark pause, but it can be potential latency killer.
1482 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1483 ShenandoahCodeRoots::arm_nmethods();
1484 }
1485 }
1486
1487 void ShenandoahHeap::op_mark() {
1488 concurrent_mark()->mark_from_roots();
1489 }
1490
1491 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1492 private:
1493 ShenandoahMarkingContext* const _ctx;
1494 ShenandoahHeapLock* const _lock;
1495
1496 public:
1497 ShenandoahFinalMarkUpdateRegionStateClosure() :
1498 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1499
1500 void heap_region_do(ShenandoahHeapRegion* r) {
1501 if (r->is_active()) {
1502 // All allocations past TAMS are implicitly live, adjust the region data.
1503 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1504 HeapWord *tams = _ctx->top_at_mark_start(r);
1505 HeapWord *top = r->top();
1506 if (top > tams) {
1507 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1508 }
1509
1510 // We are about to select the collection set, make sure it knows about
1511 // current pinning status. Also, this allows trashing more regions that
1512 // now have their pinning status dropped.
1513 if (r->is_pinned()) {
1514 if (r->pin_count() == 0) {
1515 ShenandoahHeapLocker locker(_lock);
1516 r->make_unpinned();
1517 }
1518 } else {
1519 if (r->pin_count() > 0) {
1520 ShenandoahHeapLocker locker(_lock);
1521 r->make_pinned();
1522 }
1523 }
1524
1525 // Remember limit for updating refs. It's guaranteed that we get no
1526 // from-space-refs written from here on.
1527 r->set_update_watermark_at_safepoint(r->top());
1528 } else {
1529 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1530 assert(_ctx->top_at_mark_start(r) == r->top(),
1531 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1532 }
1533 }
1534
1535 bool is_thread_safe() { return true; }
1536 };
1537
1538 void ShenandoahHeap::op_final_mark() {
1539 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1540 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1541
1542 // It is critical that we
1543 // evacuate roots right after finishing marking, so that we don't
1544 // get unmarked objects in the roots.
1545
1546 if (!cancelled_gc()) {
1547 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1548
1549 // Marking is completed, deactivate SATB barrier
1550 set_concurrent_mark_in_progress(false);
1551 mark_complete_marking_context();
1552
1553 parallel_cleaning(false /* full gc*/);
1554
1555 if (ShenandoahVerify) {
1556 verifier()->verify_roots_no_forwarded();
1557 }
1558
1559 {
1560 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_region_states);
1561 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1562 parallel_heap_region_iterate(&cl);
1563
1564 assert_pinned_region_status();
1565 }
1566
1567 // Retire the TLABs, which will force threads to reacquire their TLABs after the pause.
1568 // This is needed for two reasons. Strong one: new allocations would be with new freeset,
1569 // which would be outside the collection set, so no cset writes would happen there.
1570 // Weaker one: new allocations would happen past update watermark, and so less work would
1571 // be needed for reference updates (would update the large filler instead).
1572 if (UseTLAB) {
1573 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_manage_labs);
1574 tlabs_retire(false);
1575 }
1576
1577 {
1578 ShenandoahGCPhase phase(ShenandoahPhaseTimings::choose_cset);
1579 ShenandoahHeapLocker locker(lock());
1580 _collection_set->clear();
1581 heuristics()->choose_collection_set(_collection_set);
1582 }
1583
1584 {
1585 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_rebuild_freeset);
1586 ShenandoahHeapLocker locker(lock());
1587 _free_set->rebuild();
1588 }
1589
1590 if (!is_degenerated_gc_in_progress()) {
1591 prepare_concurrent_roots();
1592 prepare_concurrent_unloading();
1593 }
1594
1595 // If collection set has candidates, start evacuation.
1596 // Otherwise, bypass the rest of the cycle.
1597 if (!collection_set()->is_empty()) {
1598 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1599
1600 if (ShenandoahVerify) {
1601 verifier()->verify_before_evacuation();
1602 }
1603
1604 set_evacuation_in_progress(true);
1605 // From here on, we need to update references.
1606 set_has_forwarded_objects(true);
1607
1608 if (!is_degenerated_gc_in_progress()) {
1609 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1610 ShenandoahCodeRoots::arm_nmethods();
1611 }
1612 evacuate_and_update_roots();
1613 }
1614
1615 if (ShenandoahPacing) {
1616 pacer()->setup_for_evac();
1617 }
1618
1619 if (ShenandoahVerify) {
1620 // If OOM while evacuating/updating of roots, there is no guarantee of their consistencies
1621 if (!cancelled_gc()) {
1622 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::None;
1623 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1624 types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots);
1625 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots);
1626 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::StringDedupRoots);
1627 }
1628
1629 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1630 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CodeRoots);
1631 }
1632 verifier()->verify_roots_no_forwarded_except(types);
1633 }
1634 verifier()->verify_during_evacuation();
1635 }
1636 } else {
1637 if (ShenandoahVerify) {
1638 verifier()->verify_after_concmark();
1639 }
1640
1641 if (VerifyAfterGC) {
1642 Universe::verify();
1643 }
1644 }
1645
1646 } else {
1647 // If this cycle was updating references, we need to keep the has_forwarded_objects
1648 // flag on, for subsequent phases to deal with it.
1649 concurrent_mark()->cancel();
1650 set_concurrent_mark_in_progress(false);
1651
1652 if (process_references()) {
1653 // Abandon reference processing right away: pre-cleaning must have failed.
1654 ReferenceProcessor *rp = ref_processor();
1655 rp->disable_discovery();
1656 rp->abandon_partial_discovery();
1657 rp->verify_no_references_recorded();
1658 }
1659 }
1660 }
1661
1662 void ShenandoahHeap::op_conc_evac() {
1663 ShenandoahEvacuationTask task(this, _collection_set, true);
1664 workers()->run_task(&task);
1665 }
1666
1667 void ShenandoahHeap::op_stw_evac() {
1668 ShenandoahEvacuationTask task(this, _collection_set, false);
1669 workers()->run_task(&task);
1670 }
1671
1672 void ShenandoahHeap::op_updaterefs() {
1673 update_heap_references(true);
1674 }
1675
1676 void ShenandoahHeap::op_cleanup_early() {
1677 free_set()->recycle_trash();
1678 }
1679
1680 void ShenandoahHeap::op_cleanup_complete() {
1681 free_set()->recycle_trash();
1682 }
1683
1684 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask {
1685 private:
1686 ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
1687 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots;
1688
1689 public:
1690 ShenandoahConcurrentRootsEvacUpdateTask(ShenandoahPhaseTimings::Phase phase) :
1691 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Strong Roots Task"),
1692 _vm_roots(phase),
1693 _cld_roots(phase, ShenandoahHeap::heap()->workers()->active_workers()) {}
1694
1695 void work(uint worker_id) {
1696 ShenandoahConcurrentWorkerSession worker_session(worker_id);
1697 ShenandoahEvacOOMScope oom;
1698 {
1699 // vm_roots and weak_roots are OopStorage backed roots, concurrent iteration
1700 // may race against OopStorage::release() calls.
1701 ShenandoahEvacUpdateOopStorageRootsClosure cl;
1702 _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl, worker_id);
1703 }
1704
1705 {
1706 ShenandoahEvacuateUpdateRootsClosure<> cl;
1707 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1708 _cld_roots.cld_do(&clds, worker_id);
1709 }
1710 }
1711 };
1712
1713 class ShenandoahEvacUpdateCleanupOopStorageRootsClosure : public BasicOopIterateClosure {
1714 private:
1715 ShenandoahHeap* const _heap;
1716 ShenandoahMarkingContext* const _mark_context;
1717 bool _evac_in_progress;
1718 Thread* const _thread;
1719 size_t _dead_counter;
1720
1721 public:
1722 ShenandoahEvacUpdateCleanupOopStorageRootsClosure();
1723 void do_oop(oop* p);
1724 void do_oop(narrowOop* p);
1725
1726 size_t dead_counter() const;
1727 void reset_dead_counter();
1728 };
1729
1730 ShenandoahEvacUpdateCleanupOopStorageRootsClosure::ShenandoahEvacUpdateCleanupOopStorageRootsClosure() :
1731 _heap(ShenandoahHeap::heap()),
1732 _mark_context(ShenandoahHeap::heap()->marking_context()),
1733 _evac_in_progress(ShenandoahHeap::heap()->is_evacuation_in_progress()),
1734 _thread(Thread::current()),
1735 _dead_counter(0) {
1736 }
1737
1738 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(oop* p) {
1739 const oop obj = RawAccess<>::oop_load(p);
1740 if (!CompressedOops::is_null(obj)) {
1741 if (!_mark_context->is_marked(obj)) {
1742 shenandoah_assert_correct(p, obj);
1743 oop old = Atomic::cmpxchg(p, obj, oop(NULL));
1744 if (obj == old) {
1745 _dead_counter ++;
1746 }
1747 } else if (_evac_in_progress && _heap->in_collection_set(obj)) {
1748 oop resolved = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1749 if (resolved == obj) {
1750 resolved = _heap->evacuate_object(obj, _thread);
1751 }
1752 Atomic::cmpxchg(p, obj, resolved);
1753 assert(_heap->cancelled_gc() ||
1754 _mark_context->is_marked(resolved) && !_heap->in_collection_set(resolved),
1755 "Sanity");
1756 }
1757 }
1758 }
1759
1760 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(narrowOop* p) {
1761 ShouldNotReachHere();
1762 }
1763
1764 size_t ShenandoahEvacUpdateCleanupOopStorageRootsClosure::dead_counter() const {
1765 return _dead_counter;
1766 }
1767
1768 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::reset_dead_counter() {
1769 _dead_counter = 0;
1770 }
1771
1772 class ShenandoahIsCLDAliveClosure : public CLDClosure {
1773 public:
1774 void do_cld(ClassLoaderData* cld) {
1775 cld->is_alive();
1776 }
1777 };
1778
1779 class ShenandoahIsNMethodAliveClosure: public NMethodClosure {
1780 public:
1781 void do_nmethod(nmethod* n) {
1782 n->is_unloading();
1783 }
1784 };
1785
1786 // This task not only evacuates/updates marked weak roots, but also "NULL"
1787 // dead weak roots.
1788 class ShenandoahConcurrentWeakRootsEvacUpdateTask : public AbstractGangTask {
1789 private:
1790 ShenandoahWeakRoot<true /*concurrent*/> _jni_roots;
1791 ShenandoahWeakRoot<true /*concurrent*/> _string_table_roots;
1792 ShenandoahWeakRoot<true /*concurrent*/> _resolved_method_table_roots;
1793 ShenandoahWeakRoot<true /*concurrent*/> _vm_roots;
1794
1795 // Roots related to concurrent class unloading
1796 ShenandoahClassLoaderDataRoots<true /* concurrent */, false /* single thread*/>
1797 _cld_roots;
1798 ShenandoahConcurrentNMethodIterator _nmethod_itr;
1799 ShenandoahConcurrentStringDedupRoots _dedup_roots;
1800 bool _concurrent_class_unloading;
1801
1802 public:
1803 ShenandoahConcurrentWeakRootsEvacUpdateTask(ShenandoahPhaseTimings::Phase phase) :
1804 AbstractGangTask("Shenandoah Concurrent Weak Root Task"),
1805 _jni_roots(OopStorageSet::jni_weak(), phase, ShenandoahPhaseTimings::JNIWeakRoots),
1806 _string_table_roots(OopStorageSet::string_table_weak(), phase, ShenandoahPhaseTimings::StringTableRoots),
1807 _resolved_method_table_roots(OopStorageSet::resolved_method_table_weak(), phase, ShenandoahPhaseTimings::ResolvedMethodTableRoots),
1808 _vm_roots(OopStorageSet::vm_weak(), phase, ShenandoahPhaseTimings::VMWeakRoots),
1809 _cld_roots(phase, ShenandoahHeap::heap()->workers()->active_workers()),
1810 _nmethod_itr(ShenandoahCodeRoots::table()),
1811 _dedup_roots(phase),
1812 _concurrent_class_unloading(ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1813 StringTable::reset_dead_counter();
1814 ResolvedMethodTable::reset_dead_counter();
1815 if (_concurrent_class_unloading) {
1816 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
1817 _nmethod_itr.nmethods_do_begin();
1818 }
1819 }
1820
1821 ~ShenandoahConcurrentWeakRootsEvacUpdateTask() {
1822 StringTable::finish_dead_counter();
1823 ResolvedMethodTable::finish_dead_counter();
1824 if (_concurrent_class_unloading) {
1825 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
1826 _nmethod_itr.nmethods_do_end();
1827 }
1828 }
1829
1830 void work(uint worker_id) {
1831 ShenandoahConcurrentWorkerSession worker_session(worker_id);
1832 {
1833 ShenandoahEvacOOMScope oom;
1834 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
1835 // may race against OopStorage::release() calls.
1836 ShenandoahEvacUpdateCleanupOopStorageRootsClosure cl;
1837 _jni_roots.oops_do(&cl, worker_id);
1838 _vm_roots.oops_do(&cl, worker_id);
1839
1840 cl.reset_dead_counter();
1841 _string_table_roots.oops_do(&cl, worker_id);
1842 StringTable::inc_dead_counter(cl.dead_counter());
1843
1844 cl.reset_dead_counter();
1845 _resolved_method_table_roots.oops_do(&cl, worker_id);
1846 ResolvedMethodTable::inc_dead_counter(cl.dead_counter());
1847
1848 // String dedup weak roots
1849 ShenandoahForwardedIsAliveClosure is_alive;
1850 ShenandoahEvacuateUpdateRootsClosure<MO_RELEASE> keep_alive;
1851 _dedup_roots.oops_do(&is_alive, &keep_alive, worker_id);
1852 }
1853
1854 // If we are going to perform concurrent class unloading later on, we need to
1855 // cleanup the weak oops in CLD and determinate nmethod's unloading state, so that we
1856 // can cleanup immediate garbage sooner.
1857 if (_concurrent_class_unloading) {
1858 // Applies ShenandoahIsCLDAlive closure to CLDs, native barrier will either NULL the
1859 // CLD's holder or evacuate it.
1860 ShenandoahIsCLDAliveClosure is_cld_alive;
1861 _cld_roots.cld_do(&is_cld_alive, worker_id);
1862
1863 // Applies ShenandoahIsNMethodAliveClosure to registered nmethods.
1864 // The closure calls nmethod->is_unloading(). The is_unloading
1865 // state is cached, therefore, during concurrent class unloading phase,
1866 // we will not touch the metadata of unloading nmethods
1867 ShenandoahIsNMethodAliveClosure is_nmethod_alive;
1868 _nmethod_itr.nmethods_do(&is_nmethod_alive);
1869 }
1870 }
1871 };
1872
1873 void ShenandoahHeap::op_weak_roots() {
1874 if (is_concurrent_weak_root_in_progress()) {
1875 // Concurrent weak root processing
1876 {
1877 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_weak_roots_work);
1878 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_weak_roots_work);
1879 ShenandoahConcurrentWeakRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_weak_roots_work);
1880 workers()->run_task(&task);
1881 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1882 set_concurrent_weak_root_in_progress(false);
1883 }
1884 }
1885
1886 // Perform handshake to flush out dead oops
1887 {
1888 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_weak_roots_rendezvous);
1889 ShenandoahRendezvousClosure cl;
1890 Handshake::execute(&cl);
1891 }
1892 }
1893 }
1894
1895 void ShenandoahHeap::op_class_unloading() {
1896 assert (is_concurrent_weak_root_in_progress() &&
1897 ShenandoahConcurrentRoots::should_do_concurrent_class_unloading(),
1898 "Checked by caller");
1899 _unloader.unload();
1900 set_concurrent_weak_root_in_progress(false);
1901 }
1902
1903 void ShenandoahHeap::op_strong_roots() {
1904 assert(is_concurrent_strong_root_in_progress(), "Checked by caller");
1905 ShenandoahConcurrentRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_strong_roots);
1906 workers()->run_task(&task);
1907 set_concurrent_strong_root_in_progress(false);
1908 }
1909
1910 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1911 private:
1912 ShenandoahMarkingContext* const _ctx;
1913 public:
1914 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1915
1916 void heap_region_do(ShenandoahHeapRegion* r) {
1917 if (r->is_active()) {
1918 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1919 // anyway to capture any updates that happened since now.
1920 r->clear_live_data();
1921 _ctx->capture_top_at_mark_start(r);
1922 }
1923 }
1924
1925 bool is_thread_safe() { return true; }
1926 };
1927
1928 void ShenandoahHeap::op_reset() {
1929 if (ShenandoahPacing) {
1930 pacer()->setup_for_reset();
1931 }
1932 reset_mark_bitmap();
1933
1934 ShenandoahResetUpdateRegionStateClosure cl;
1935 parallel_heap_region_iterate(&cl);
1936 }
1937
1938 void ShenandoahHeap::op_preclean() {
1939 if (ShenandoahPacing) {
1940 pacer()->setup_for_preclean();
1941 }
1942 concurrent_mark()->preclean_weak_refs();
1943 }
1944
1945 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1946 ShenandoahMetricsSnapshot metrics;
1947 metrics.snap_before();
1948
1949 full_gc()->do_it(cause);
1950
1951 metrics.snap_after();
1952
1953 if (metrics.is_good_progress()) {
1954 _progress_last_gc.set();
1955 } else {
1956 // Nothing to do. Tell the allocation path that we have failed to make
1957 // progress, and it can finally fail.
1958 _progress_last_gc.unset();
1959 }
1960 }
1961
1962 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1963 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1964 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1965 // some phase, we have to upgrade the Degenerate GC to Full GC.
1966
1967 clear_cancelled_gc();
1968
1969 ShenandoahMetricsSnapshot metrics;
1970 metrics.snap_before();
1971
1972 switch (point) {
1973 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1974 // but enters it at different points, depending on which concurrent phase had
1975 // degenerated.
1976
1977 case _degenerated_outside_cycle:
1978 // We have degenerated from outside the cycle, which means something is bad with
1979 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1980 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1981 // we can do the most aggressive degen cycle, which includes processing references and
1982 // class unloading, unless those features are explicitly disabled.
1983 //
1984 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1985 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1986 set_process_references(heuristics()->can_process_references());
1987 set_unload_classes(heuristics()->can_unload_classes());
1988
1989 op_reset();
1990
1991 op_init_mark();
1992 if (cancelled_gc()) {
1993 op_degenerated_fail();
1994 return;
1995 }
1996
1997 case _degenerated_mark:
1998 op_final_mark();
1999 if (cancelled_gc()) {
2000 op_degenerated_fail();
2001 return;
2002 }
2003
2004 if (!has_forwarded_objects() && ShenandoahConcurrentRoots::can_do_concurrent_class_unloading()) {
2005 // Disarm nmethods that armed for concurrent mark. On normal cycle, it would
2006 // be disarmed while conc-roots phase is running.
2007 // TODO: Call op_conc_roots() here instead
2008 ShenandoahCodeRoots::disarm_nmethods();
2009 }
2010
2011 op_cleanup_early();
2012
2013 case _degenerated_evac:
2014 // If heuristics thinks we should do the cycle, this flag would be set,
2015 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
2016 if (is_evacuation_in_progress()) {
2017
2018 // Degeneration under oom-evac protocol might have left some objects in
2019 // collection set un-evacuated. Restart evacuation from the beginning to
2020 // capture all objects. For all the objects that are already evacuated,
2021 // it would be a simple check, which is supposed to be fast. This is also
2022 // safe to do even without degeneration, as CSet iterator is at beginning
2023 // in preparation for evacuation anyway.
2024 //
2025 // Before doing that, we need to make sure we never had any cset-pinned
2026 // regions. This may happen if allocation failure happened when evacuating
2027 // the about-to-be-pinned object, oom-evac protocol left the object in
2028 // the collection set, and then the pin reached the cset region. If we continue
2029 // the cycle here, we would trash the cset and alive objects in it. To avoid
2030 // it, we fail degeneration right away and slide into Full GC to recover.
2031
2032 {
2033 sync_pinned_region_status();
2034 collection_set()->clear_current_index();
2035
2036 ShenandoahHeapRegion* r;
2037 while ((r = collection_set()->next()) != NULL) {
2038 if (r->is_pinned()) {
2039 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
2040 op_degenerated_fail();
2041 return;
2042 }
2043 }
2044
2045 collection_set()->clear_current_index();
2046 }
2047
2048 op_stw_evac();
2049 if (cancelled_gc()) {
2050 op_degenerated_fail();
2051 return;
2052 }
2053 }
2054
2055 // If heuristics thinks we should do the cycle, this flag would be set,
2056 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
2057 if (has_forwarded_objects()) {
2058 op_init_updaterefs();
2059 if (cancelled_gc()) {
2060 op_degenerated_fail();
2061 return;
2062 }
2063 }
2064
2065 case _degenerated_updaterefs:
2066 if (has_forwarded_objects()) {
2067 op_final_updaterefs();
2068 if (cancelled_gc()) {
2069 op_degenerated_fail();
2070 return;
2071 }
2072 }
2073
2074 op_cleanup_complete();
2075 break;
2076
2077 default:
2078 ShouldNotReachHere();
2079 }
2080
2081 if (ShenandoahVerify) {
2082 verifier()->verify_after_degenerated();
2083 }
2084
2085 if (VerifyAfterGC) {
2086 Universe::verify();
2087 }
2088
2089 metrics.snap_after();
2090
2091 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
2092 // because that probably means the heap is overloaded and/or fragmented.
2093 if (!metrics.is_good_progress()) {
2094 _progress_last_gc.unset();
2095 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
2096 op_degenerated_futile();
2097 } else {
2098 _progress_last_gc.set();
2099 }
2100 }
2101
2102 void ShenandoahHeap::op_degenerated_fail() {
2103 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
2104 shenandoah_policy()->record_degenerated_upgrade_to_full();
2105 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2106 }
2107
2108 void ShenandoahHeap::op_degenerated_futile() {
2109 shenandoah_policy()->record_degenerated_upgrade_to_full();
2110 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2111 }
2112
2113 void ShenandoahHeap::force_satb_flush_all_threads() {
2114 if (!is_concurrent_mark_in_progress()) {
2115 // No need to flush SATBs
2116 return;
2117 }
2118
2119 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2120 ShenandoahThreadLocalData::set_force_satb_flush(t, true);
2121 }
2122 // The threads are not "acquiring" their thread-local data, but it does not
2123 // hurt to "release" the updates here anyway.
2124 OrderAccess::fence();
2125 }
2126
2127 void ShenandoahHeap::set_gc_state_all_threads(char state) {
2128 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2129 ShenandoahThreadLocalData::set_gc_state(t, state);
2130 }
2131 }
2132
2133 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
2134 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
2135 _gc_state.set_cond(mask, value);
2136 set_gc_state_all_threads(_gc_state.raw_value());
2137 }
2138
2139 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
2140 if (has_forwarded_objects()) {
2141 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
2142 } else {
2143 set_gc_state_mask(MARKING, in_progress);
2144 }
2145 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
2146 }
2147
2148 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
2149 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
2150 set_gc_state_mask(EVACUATION, in_progress);
2151 }
2152
2153 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
2154 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
2155 if (in_progress) {
2156 _concurrent_strong_root_in_progress.set();
2157 } else {
2158 _concurrent_strong_root_in_progress.unset();
2159 }
2160 }
2161
2162 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool in_progress) {
2163 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
2164 if (in_progress) {
2165 _concurrent_weak_root_in_progress.set();
2166 } else {
2167 _concurrent_weak_root_in_progress.unset();
2168 }
2169 }
2170
2171 void ShenandoahHeap::ref_processing_init() {
2172 assert(_max_workers > 0, "Sanity");
2173
2174 _ref_processor =
2175 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
2176 _ref_proc_mt_processing, // MT processing
2177 _max_workers, // Degree of MT processing
2178 _ref_proc_mt_discovery, // MT discovery
2179 _max_workers, // Degree of MT discovery
2180 false, // Reference discovery is not atomic
2181 NULL, // No closure, should be installed before use
2182 true); // Scale worker threads
2183
2184 shenandoah_assert_rp_isalive_not_installed();
2185 }
2186
2187 GCTracer* ShenandoahHeap::tracer() {
2188 return shenandoah_policy()->tracer();
2189 }
2190
2191 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
2192 return _free_set->used();
2193 }
2194
2195 bool ShenandoahHeap::try_cancel_gc() {
2196 while (true) {
2197 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
2198 if (prev == CANCELLABLE) return true;
2199 else if (prev == CANCELLED) return false;
2200 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
2201 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
2202 if (Thread::current()->is_Java_thread()) {
2203 // We need to provide a safepoint here, otherwise we might
2204 // spin forever if a SP is pending.
2205 ThreadBlockInVM sp(JavaThread::current());
2206 SpinPause();
2207 }
2208 }
2209 }
2210
2211 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
2212 if (try_cancel_gc()) {
2213 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
2214 log_info(gc)("%s", msg.buffer());
2215 Events::log(Thread::current(), "%s", msg.buffer());
2216 }
2217 }
2218
2219 uint ShenandoahHeap::max_workers() {
2220 return _max_workers;
2221 }
2222
2223 void ShenandoahHeap::stop() {
2224 // The shutdown sequence should be able to terminate when GC is running.
2225
2226 // Step 0. Notify policy to disable event recording.
2227 _shenandoah_policy->record_shutdown();
2228
2229 // Step 1. Notify control thread that we are in shutdown.
2230 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
2231 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
2232 control_thread()->prepare_for_graceful_shutdown();
2233
2234 // Step 2. Notify GC workers that we are cancelling GC.
2235 cancel_gc(GCCause::_shenandoah_stop_vm);
2236
2237 // Step 3. Wait until GC worker exits normally.
2238 control_thread()->stop();
2239
2240 // Step 4. Stop String Dedup thread if it is active
2241 if (ShenandoahStringDedup::is_enabled()) {
2242 ShenandoahStringDedup::stop();
2243 }
2244 }
2245
2246 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
2247 if (!unload_classes()) return;
2248
2249 // Unload classes and purge SystemDictionary.
2250 {
2251 ShenandoahGCPhase phase(full_gc ?
2252 ShenandoahPhaseTimings::full_gc_purge_class_unload :
2253 ShenandoahPhaseTimings::purge_class_unload);
2254 bool purged_class = SystemDictionary::do_unloading(gc_timer());
2255
2256 ShenandoahIsAliveSelector is_alive;
2257 uint num_workers = _workers->active_workers();
2258 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
2259 _workers->run_task(&unlink_task);
2260 }
2261
2262 {
2263 ShenandoahGCPhase phase(full_gc ?
2264 ShenandoahPhaseTimings::full_gc_purge_cldg :
2265 ShenandoahPhaseTimings::purge_cldg);
2266 ClassLoaderDataGraph::purge();
2267 }
2268 // Resize and verify metaspace
2269 MetaspaceGC::compute_new_size();
2270 MetaspaceUtils::verify_metrics();
2271 }
2272
2273 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
2274 // so they should not have forwarded oops.
2275 // However, we do need to "null" dead oops in the roots, if can not be done
2276 // in concurrent cycles.
2277 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
2278 ShenandoahGCPhase root_phase(full_gc ?
2279 ShenandoahPhaseTimings::full_gc_purge :
2280 ShenandoahPhaseTimings::purge);
2281 uint num_workers = _workers->active_workers();
2282 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
2283 ShenandoahPhaseTimings::full_gc_purge_weak_par :
2284 ShenandoahPhaseTimings::purge_weak_par;
2285 ShenandoahGCPhase phase(timing_phase);
2286 ShenandoahGCWorkerPhase worker_phase(timing_phase);
2287
2288 // Cleanup weak roots
2289 if (has_forwarded_objects()) {
2290 ShenandoahForwardedIsAliveClosure is_alive;
2291 ShenandoahUpdateRefsClosure keep_alive;
2292 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2293 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2294 _workers->run_task(&cleaning_task);
2295 } else {
2296 ShenandoahIsAliveClosure is_alive;
2297 #ifdef ASSERT
2298 ShenandoahAssertNotForwardedClosure verify_cl;
2299 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2300 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2301 #else
2302 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2303 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2304 #endif
2305 _workers->run_task(&cleaning_task);
2306 }
2307 }
2308
2309 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2310 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2311 stw_process_weak_roots(full_gc);
2312 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2313 stw_unload_classes(full_gc);
2314 }
2315 }
2316
2317 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2318 set_gc_state_mask(HAS_FORWARDED, cond);
2319 }
2320
2321 void ShenandoahHeap::set_process_references(bool pr) {
2322 _process_references.set_cond(pr);
2323 }
2324
2325 void ShenandoahHeap::set_unload_classes(bool uc) {
2326 _unload_classes.set_cond(uc);
2327 }
2328
2329 bool ShenandoahHeap::process_references() const {
2330 return _process_references.is_set();
2331 }
2332
2333 bool ShenandoahHeap::unload_classes() const {
2334 return _unload_classes.is_set();
2335 }
2336
2337 address ShenandoahHeap::in_cset_fast_test_addr() {
2338 ShenandoahHeap* heap = ShenandoahHeap::heap();
2339 assert(heap->collection_set() != NULL, "Sanity");
2340 return (address) heap->collection_set()->biased_map_address();
2341 }
2342
2343 address ShenandoahHeap::cancelled_gc_addr() {
2344 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
2345 }
2346
2347 address ShenandoahHeap::gc_state_addr() {
2348 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2349 }
2350
2351 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2352 return Atomic::load_acquire(&_bytes_allocated_since_gc_start);
2353 }
2354
2355 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2356 Atomic::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2357 }
2358
2359 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2360 _degenerated_gc_in_progress.set_cond(in_progress);
2361 }
2362
2363 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2364 _full_gc_in_progress.set_cond(in_progress);
2365 }
2366
2367 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2368 assert (is_full_gc_in_progress(), "should be");
2369 _full_gc_move_in_progress.set_cond(in_progress);
2370 }
2371
2372 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2373 set_gc_state_mask(UPDATEREFS, in_progress);
2374 }
2375
2376 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2377 ShenandoahCodeRoots::register_nmethod(nm);
2378 }
2379
2380 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2381 ShenandoahCodeRoots::unregister_nmethod(nm);
2382 }
2383
2384 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
2385 ShenandoahCodeRoots::flush_nmethod(nm);
2386 }
2387
2388 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2389 heap_region_containing(o)->record_pin();
2390 return o;
2391 }
2392
2393 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2394 heap_region_containing(o)->record_unpin();
2395 }
2396
2397 void ShenandoahHeap::sync_pinned_region_status() {
2398 ShenandoahHeapLocker locker(lock());
2399
2400 for (size_t i = 0; i < num_regions(); i++) {
2401 ShenandoahHeapRegion *r = get_region(i);
2402 if (r->is_active()) {
2403 if (r->is_pinned()) {
2404 if (r->pin_count() == 0) {
2405 r->make_unpinned();
2406 }
2407 } else {
2408 if (r->pin_count() > 0) {
2409 r->make_pinned();
2410 }
2411 }
2412 }
2413 }
2414
2415 assert_pinned_region_status();
2416 }
2417
2418 #ifdef ASSERT
2419 void ShenandoahHeap::assert_pinned_region_status() {
2420 for (size_t i = 0; i < num_regions(); i++) {
2421 ShenandoahHeapRegion* r = get_region(i);
2422 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2423 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2424 }
2425 }
2426 #endif
2427
2428 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
2429 return _gc_timer;
2430 }
2431
2432 void ShenandoahHeap::prepare_concurrent_roots() {
2433 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2434 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
2435 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
2436 set_concurrent_weak_root_in_progress(true);
2437 }
2438 }
2439
2440 void ShenandoahHeap::prepare_concurrent_unloading() {
2441 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2442 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2443 _unloader.prepare();
2444 }
2445 }
2446
2447 void ShenandoahHeap::finish_concurrent_unloading() {
2448 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2449 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2450 _unloader.finish();
2451 }
2452 }
2453
2454 #ifdef ASSERT
2455 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2456 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2457
2458 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2459 if (UseDynamicNumberOfGCThreads) {
2460 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2461 } else {
2462 // Use ParallelGCThreads inside safepoints
2463 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
2464 }
2465 } else {
2466 if (UseDynamicNumberOfGCThreads) {
2467 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2468 } else {
2469 // Use ConcGCThreads outside safepoints
2470 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2471 }
2472 }
2473 }
2474 #endif
2475
2476 ShenandoahVerifier* ShenandoahHeap::verifier() {
2477 guarantee(ShenandoahVerify, "Should be enabled");
2478 assert (_verifier != NULL, "sanity");
2479 return _verifier;
2480 }
2481
2482 template<class T>
2483 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2484 private:
2485 T cl;
2486 ShenandoahHeap* _heap;
2487 ShenandoahRegionIterator* _regions;
2488 bool _concurrent;
2489 public:
2490 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2491 AbstractGangTask("Concurrent Update References Task"),
2492 cl(T()),
2493 _heap(ShenandoahHeap::heap()),
2494 _regions(regions),
2495 _concurrent(concurrent) {
2496 }
2497
2498 void work(uint worker_id) {
2499 if (_concurrent) {
2500 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2501 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2502 do_work();
2503 } else {
2504 ShenandoahParallelWorkerSession worker_session(worker_id);
2505 do_work();
2506 }
2507 }
2508
2509 private:
2510 void do_work() {
2511 ShenandoahHeapRegion* r = _regions->next();
2512 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2513 while (r != NULL) {
2514 HeapWord* update_watermark = r->get_update_watermark();
2515 assert (update_watermark >= r->bottom(), "sanity");
2516 if (r->is_active() && !r->is_cset()) {
2517 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2518 }
2519 if (ShenandoahPacing) {
2520 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2521 }
2522 if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
2523 return;
2524 }
2525 r = _regions->next();
2526 }
2527 }
2528 };
2529
2530 void ShenandoahHeap::update_heap_references(bool concurrent) {
2531 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
2532 workers()->run_task(&task);
2533 }
2534
2535 void ShenandoahHeap::op_init_updaterefs() {
2536 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2537
2538 set_evacuation_in_progress(false);
2539
2540 // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
2541 // make them parsable for update code to work correctly. Plus, we can compute new sizes
2542 // for future GCLABs here.
2543 if (UseTLAB) {
2544 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_manage_gclabs);
2545 gclabs_retire(true);
2546 }
2547
2548 if (ShenandoahVerify) {
2549 if (!is_degenerated_gc_in_progress()) {
2550 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2551 }
2552 verifier()->verify_before_updaterefs();
2553 }
2554
2555 set_update_refs_in_progress(true);
2556
2557 _update_refs_iterator.reset();
2558
2559 if (ShenandoahPacing) {
2560 pacer()->setup_for_updaterefs();
2561 }
2562 }
2563
2564 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2565 private:
2566 ShenandoahHeapLock* const _lock;
2567
2568 public:
2569 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2570
2571 void heap_region_do(ShenandoahHeapRegion* r) {
2572 // Drop unnecessary "pinned" state from regions that does not have CP marks
2573 // anymore, as this would allow trashing them.
2574
2575 if (r->is_active()) {
2576 if (r->is_pinned()) {
2577 if (r->pin_count() == 0) {
2578 ShenandoahHeapLocker locker(_lock);
2579 r->make_unpinned();
2580 }
2581 } else {
2582 if (r->pin_count() > 0) {
2583 ShenandoahHeapLocker locker(_lock);
2584 r->make_pinned();
2585 }
2586 }
2587 }
2588 }
2589
2590 bool is_thread_safe() { return true; }
2591 };
2592
2593 void ShenandoahHeap::op_final_updaterefs() {
2594 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2595
2596 finish_concurrent_unloading();
2597
2598 // Check if there is left-over work, and finish it
2599 if (_update_refs_iterator.has_next()) {
2600 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2601
2602 // Finish updating references where we left off.
2603 clear_cancelled_gc();
2604 update_heap_references(false);
2605 }
2606
2607 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2608 // everything. On degenerated paths, cancelled gc would not be set anyway.
2609 if (cancelled_gc()) {
2610 clear_cancelled_gc();
2611 }
2612 assert(!cancelled_gc(), "Should have been done right before");
2613
2614 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2615 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2616 }
2617
2618 if (is_degenerated_gc_in_progress()) {
2619 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2620 } else {
2621 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2622 }
2623
2624 // Has to be done before cset is clear
2625 if (ShenandoahVerify) {
2626 verifier()->verify_roots_in_to_space();
2627 }
2628
2629 {
2630 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_update_region_states);
2631 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2632 parallel_heap_region_iterate(&cl);
2633
2634 assert_pinned_region_status();
2635 }
2636
2637 {
2638 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2639 trash_cset_regions();
2640 }
2641
2642 set_has_forwarded_objects(false);
2643 set_update_refs_in_progress(false);
2644
2645 if (ShenandoahVerify) {
2646 verifier()->verify_after_updaterefs();
2647 }
2648
2649 if (VerifyAfterGC) {
2650 Universe::verify();
2651 }
2652
2653 {
2654 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_rebuild_freeset);
2655 ShenandoahHeapLocker locker(lock());
2656 _free_set->rebuild();
2657 }
2658 }
2659
2660 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2661 print_on(st);
2662 print_heap_regions_on(st);
2663 }
2664
2665 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2666 size_t slice = r->index() / _bitmap_regions_per_slice;
2667
2668 size_t regions_from = _bitmap_regions_per_slice * slice;
2669 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2670 for (size_t g = regions_from; g < regions_to; g++) {
2671 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2672 if (skip_self && g == r->index()) continue;
2673 if (get_region(g)->is_committed()) {
2674 return true;
2675 }
2676 }
2677 return false;
2678 }
2679
2680 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2681 shenandoah_assert_heaplocked();
2682
2683 // Bitmaps in special regions do not need commits
2684 if (_bitmap_region_special) {
2685 return true;
2686 }
2687
2688 if (is_bitmap_slice_committed(r, true)) {
2689 // Some other region from the group is already committed, meaning the bitmap
2690 // slice is already committed, we exit right away.
2691 return true;
2692 }
2693
2694 // Commit the bitmap slice:
2695 size_t slice = r->index() / _bitmap_regions_per_slice;
2696 size_t off = _bitmap_bytes_per_slice * slice;
2697 size_t len = _bitmap_bytes_per_slice;
2698 char* start = (char*) _bitmap_region.start() + off;
2699
2700 if (!os::commit_memory(start, len, false)) {
2701 return false;
2702 }
2703
2704 if (AlwaysPreTouch) {
2705 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size);
2706 }
2707
2708 return true;
2709 }
2710
2711 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2712 shenandoah_assert_heaplocked();
2713
2714 // Bitmaps in special regions do not need uncommits
2715 if (_bitmap_region_special) {
2716 return true;
2717 }
2718
2719 if (is_bitmap_slice_committed(r, true)) {
2720 // Some other region from the group is still committed, meaning the bitmap
2721 // slice is should stay committed, exit right away.
2722 return true;
2723 }
2724
2725 // Uncommit the bitmap slice:
2726 size_t slice = r->index() / _bitmap_regions_per_slice;
2727 size_t off = _bitmap_bytes_per_slice * slice;
2728 size_t len = _bitmap_bytes_per_slice;
2729 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2730 return false;
2731 }
2732 return true;
2733 }
2734
2735 void ShenandoahHeap::safepoint_synchronize_begin() {
2736 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2737 SuspendibleThreadSet::synchronize();
2738 }
2739 }
2740
2741 void ShenandoahHeap::safepoint_synchronize_end() {
2742 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2743 SuspendibleThreadSet::desynchronize();
2744 }
2745 }
2746
2747 void ShenandoahHeap::vmop_entry_init_mark() {
2748 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2749 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::init_mark_gross);
2750
2751 try_inject_alloc_failure();
2752 VM_ShenandoahInitMark op;
2753 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2754 }
2755
2756 void ShenandoahHeap::vmop_entry_final_mark() {
2757 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2758 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_mark_gross);
2759
2760 try_inject_alloc_failure();
2761 VM_ShenandoahFinalMarkStartEvac op;
2762 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2763 }
2764
2765 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2766 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2767 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::init_update_refs_gross);
2768
2769 try_inject_alloc_failure();
2770 VM_ShenandoahInitUpdateRefs op;
2771 VMThread::execute(&op);
2772 }
2773
2774 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2775 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2776 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_update_refs_gross);
2777
2778 try_inject_alloc_failure();
2779 VM_ShenandoahFinalUpdateRefs op;
2780 VMThread::execute(&op);
2781 }
2782
2783 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2784 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2785 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::full_gc_gross);
2786
2787 try_inject_alloc_failure();
2788 VM_ShenandoahFullGC op(cause);
2789 VMThread::execute(&op);
2790 }
2791
2792 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2793 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2794 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::degen_gc_gross);
2795
2796 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2797 VMThread::execute(°enerated_gc);
2798 }
2799
2800 void ShenandoahHeap::entry_init_mark() {
2801 const char* msg = init_mark_event_message();
2802 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::init_mark);
2803 EventMark em("%s", msg);
2804
2805 ShenandoahWorkerScope scope(workers(),
2806 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2807 "init marking");
2808
2809 op_init_mark();
2810 }
2811
2812 void ShenandoahHeap::entry_final_mark() {
2813 const char* msg = final_mark_event_message();
2814 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_mark);
2815 EventMark em("%s", msg);
2816
2817 ShenandoahWorkerScope scope(workers(),
2818 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2819 "final marking");
2820
2821 op_final_mark();
2822 }
2823
2824 void ShenandoahHeap::entry_init_updaterefs() {
2825 static const char* msg = "Pause Init Update Refs";
2826 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::init_update_refs);
2827 EventMark em("%s", msg);
2828
2829 // No workers used in this phase, no setup required
2830
2831 op_init_updaterefs();
2832 }
2833
2834 void ShenandoahHeap::entry_final_updaterefs() {
2835 static const char* msg = "Pause Final Update Refs";
2836 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_update_refs);
2837 EventMark em("%s", msg);
2838
2839 ShenandoahWorkerScope scope(workers(),
2840 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2841 "final reference update");
2842
2843 op_final_updaterefs();
2844 }
2845
2846 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2847 static const char* msg = "Pause Full";
2848 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::full_gc, true /* log_heap_usage */);
2849 EventMark em("%s", msg);
2850
2851 ShenandoahWorkerScope scope(workers(),
2852 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2853 "full gc");
2854
2855 op_full(cause);
2856 }
2857
2858 void ShenandoahHeap::entry_degenerated(int point) {
2859 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2860 const char* msg = degen_event_message(dpoint);
2861 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::degen_gc, true /* log_heap_usage */);
2862 EventMark em("%s", msg);
2863
2864 ShenandoahWorkerScope scope(workers(),
2865 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2866 "stw degenerated gc");
2867
2868 set_degenerated_gc_in_progress(true);
2869 op_degenerated(dpoint);
2870 set_degenerated_gc_in_progress(false);
2871 }
2872
2873 void ShenandoahHeap::entry_mark() {
2874 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2875
2876 const char* msg = conc_mark_event_message();
2877 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_mark);
2878 EventMark em("%s", msg);
2879
2880 ShenandoahWorkerScope scope(workers(),
2881 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2882 "concurrent marking");
2883
2884 try_inject_alloc_failure();
2885 op_mark();
2886 }
2887
2888 void ShenandoahHeap::entry_evac() {
2889 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2890
2891 static const char* msg = "Concurrent evacuation";
2892 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_evac);
2893 EventMark em("%s", msg);
2894
2895 ShenandoahWorkerScope scope(workers(),
2896 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2897 "concurrent evacuation");
2898
2899 try_inject_alloc_failure();
2900 op_conc_evac();
2901 }
2902
2903 void ShenandoahHeap::entry_updaterefs() {
2904 static const char* msg = "Concurrent update references";
2905 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_update_refs);
2906 EventMark em("%s", msg);
2907
2908 ShenandoahWorkerScope scope(workers(),
2909 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2910 "concurrent reference update");
2911
2912 try_inject_alloc_failure();
2913 op_updaterefs();
2914 }
2915
2916 void ShenandoahHeap::entry_weak_roots() {
2917 static const char* msg = "Concurrent weak roots";
2918 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_weak_roots);
2919 EventMark em("%s", msg);
2920
2921 ShenandoahWorkerScope scope(workers(),
2922 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2923 "concurrent weak root");
2924
2925 try_inject_alloc_failure();
2926 op_weak_roots();
2927 }
2928
2929 void ShenandoahHeap::entry_class_unloading() {
2930 static const char* msg = "Concurrent class unloading";
2931 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_class_unload);
2932 EventMark em("%s", msg);
2933
2934 ShenandoahWorkerScope scope(workers(),
2935 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2936 "concurrent class unloading");
2937
2938 try_inject_alloc_failure();
2939 op_class_unloading();
2940 }
2941
2942 void ShenandoahHeap::entry_strong_roots() {
2943 static const char* msg = "Concurrent strong roots";
2944 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_strong_roots);
2945 EventMark em("%s", msg);
2946
2947 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_strong_roots);
2948
2949 ShenandoahWorkerScope scope(workers(),
2950 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2951 "concurrent strong root");
2952
2953 try_inject_alloc_failure();
2954 op_strong_roots();
2955 }
2956
2957 void ShenandoahHeap::entry_cleanup_early() {
2958 static const char* msg = "Concurrent cleanup";
2959 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_cleanup_early, true /* log_heap_usage */);
2960 EventMark em("%s", msg);
2961
2962 // This phase does not use workers, no need for setup
2963
2964 try_inject_alloc_failure();
2965 op_cleanup_early();
2966 }
2967
2968 void ShenandoahHeap::entry_cleanup_complete() {
2969 static const char* msg = "Concurrent cleanup";
2970 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_cleanup_complete, true /* log_heap_usage */);
2971 EventMark em("%s", msg);
2972
2973 // This phase does not use workers, no need for setup
2974
2975 try_inject_alloc_failure();
2976 op_cleanup_complete();
2977 }
2978
2979 void ShenandoahHeap::entry_reset() {
2980 static const char* msg = "Concurrent reset";
2981 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_reset);
2982 EventMark em("%s", msg);
2983
2984 ShenandoahWorkerScope scope(workers(),
2985 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2986 "concurrent reset");
2987
2988 try_inject_alloc_failure();
2989 op_reset();
2990 }
2991
2992 void ShenandoahHeap::entry_preclean() {
2993 if (ShenandoahPreclean && process_references()) {
2994 static const char* msg = "Concurrent precleaning";
2995 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_preclean);
2996 EventMark em("%s", msg);
2997
2998 ShenandoahWorkerScope scope(workers(),
2999 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
3000 "concurrent preclean",
3001 /* check_workers = */ false);
3002
3003 try_inject_alloc_failure();
3004 op_preclean();
3005 }
3006 }
3007
3008 void ShenandoahHeap::entry_uncommit(double shrink_before) {
3009 static const char *msg = "Concurrent uncommit";
3010 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
3011 EventMark em("%s", msg);
3012
3013 op_uncommit(shrink_before);
3014 }
3015
3016 void ShenandoahHeap::try_inject_alloc_failure() {
3017 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
3018 _inject_alloc_failure.set();
3019 os::naked_short_sleep(1);
3020 if (cancelled_gc()) {
3021 log_info(gc)("Allocation failure was successfully injected");
3022 }
3023 }
3024 }
3025
3026 bool ShenandoahHeap::should_inject_alloc_failure() {
3027 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
3028 }
3029
3030 void ShenandoahHeap::initialize_serviceability() {
3031 _memory_pool = new ShenandoahMemoryPool(this);
3032 _cycle_memory_manager.add_pool(_memory_pool);
3033 _stw_memory_manager.add_pool(_memory_pool);
3034 }
3035
3036 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
3037 GrowableArray<GCMemoryManager*> memory_managers(2);
3038 memory_managers.append(&_cycle_memory_manager);
3039 memory_managers.append(&_stw_memory_manager);
3040 return memory_managers;
3041 }
3042
3043 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
3044 GrowableArray<MemoryPool*> memory_pools(1);
3045 memory_pools.append(_memory_pool);
3046 return memory_pools;
3047 }
3048
3049 MemoryUsage ShenandoahHeap::memory_usage() {
3050 return _memory_pool->get_memory_usage();
3051 }
3052
3053 ShenandoahRegionIterator::ShenandoahRegionIterator() :
3054 _heap(ShenandoahHeap::heap()),
3055 _index(0) {}
3056
3057 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
3058 _heap(heap),
3059 _index(0) {}
3060
3061 void ShenandoahRegionIterator::reset() {
3062 _index = 0;
3063 }
3064
3065 bool ShenandoahRegionIterator::has_next() const {
3066 return _index < _heap->num_regions();
3067 }
3068
3069 char ShenandoahHeap::gc_state() const {
3070 return _gc_state.raw_value();
3071 }
3072
3073 void ShenandoahHeap::deduplicate_string(oop str) {
3074 assert(java_lang_String::is_instance(str), "invariant");
3075
3076 if (ShenandoahStringDedup::is_enabled()) {
3077 ShenandoahStringDedup::deduplicate(str);
3078 }
3079 }
3080
3081 const char* ShenandoahHeap::init_mark_event_message() const {
3082 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3083
3084 bool proc_refs = process_references();
3085 bool unload_cls = unload_classes();
3086
3087 if (proc_refs && unload_cls) {
3088 return "Pause Init Mark (process weakrefs) (unload classes)";
3089 } else if (proc_refs) {
3090 return "Pause Init Mark (process weakrefs)";
3091 } else if (unload_cls) {
3092 return "Pause Init Mark (unload classes)";
3093 } else {
3094 return "Pause Init Mark";
3095 }
3096 }
3097
3098 const char* ShenandoahHeap::final_mark_event_message() const {
3099 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3100
3101 bool proc_refs = process_references();
3102 bool unload_cls = unload_classes();
3103
3104 if (proc_refs && unload_cls) {
3105 return "Pause Final Mark (process weakrefs) (unload classes)";
3106 } else if (proc_refs) {
3107 return "Pause Final Mark (process weakrefs)";
3108 } else if (unload_cls) {
3109 return "Pause Final Mark (unload classes)";
3110 } else {
3111 return "Pause Final Mark";
3112 }
3113 }
3114
3115 const char* ShenandoahHeap::conc_mark_event_message() const {
3116 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3117
3118 bool proc_refs = process_references();
3119 bool unload_cls = unload_classes();
3120
3121 if (proc_refs && unload_cls) {
3122 return "Concurrent marking (process weakrefs) (unload classes)";
3123 } else if (proc_refs) {
3124 return "Concurrent marking (process weakrefs)";
3125 } else if (unload_cls) {
3126 return "Concurrent marking (unload classes)";
3127 } else {
3128 return "Concurrent marking";
3129 }
3130 }
3131
3132 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
3133 switch (point) {
3134 case _degenerated_unset:
3135 return "Pause Degenerated GC (<UNSET>)";
3136 case _degenerated_outside_cycle:
3137 return "Pause Degenerated GC (Outside of Cycle)";
3138 case _degenerated_mark:
3139 return "Pause Degenerated GC (Mark)";
3140 case _degenerated_evac:
3141 return "Pause Degenerated GC (Evacuation)";
3142 case _degenerated_updaterefs:
3143 return "Pause Degenerated GC (Update Refs)";
3144 default:
3145 ShouldNotReachHere();
3146 return "ERROR";
3147 }
3148 }
3149
3150 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
3151 #ifdef ASSERT
3152 assert(_liveness_cache != NULL, "sanity");
3153 assert(worker_id < _max_workers, "sanity");
3154 for (uint i = 0; i < num_regions(); i++) {
3155 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
3156 }
3157 #endif
3158 return _liveness_cache[worker_id];
3159 }
3160
3161 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
3162 assert(worker_id < _max_workers, "sanity");
3163 assert(_liveness_cache != NULL, "sanity");
3164 ShenandoahLiveData* ld = _liveness_cache[worker_id];
3165 for (uint i = 0; i < num_regions(); i++) {
3166 ShenandoahLiveData live = ld[i];
3167 if (live > 0) {
3168 ShenandoahHeapRegion* r = get_region(i);
3169 r->increase_live_data_gc_words(live);
3170 ld[i] = 0;
3171 }
3172 }
3173 }