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(_sh);
974 do_work();
975 } else {
976 ShenandoahParallelWorkerSession worker_session(worker_id);
977 ShenandoahEvacOOMScope oom_evac_scope(_sh);
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 ShenandoahRetireGCLABClosure : public ThreadClosure {
1048 public:
1049 void do_thread(Thread* thread) {
1050 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1051 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1052 gclab->retire();
1053 }
1054 };
1055
1056 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
1057 if (UseTLAB) {
1058 CollectedHeap::ensure_parsability(retire_tlabs);
1059 }
1060 ShenandoahRetireGCLABClosure cl;
1061 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1062 cl.do_thread(t);
1063 }
1064 workers()->threads_do(&cl);
1065 }
1066
1067 void ShenandoahHeap::resize_tlabs() {
1068 CollectedHeap::resize_all_tlabs();
1069 }
1070
1071 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1072 private:
1073 ShenandoahRootEvacuator* _rp;
1074
1075 public:
1076 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1077 AbstractGangTask("Shenandoah evacuate and update roots"),
1078 _rp(rp) {}
1079
1080 void work(uint worker_id) {
1081 ShenandoahParallelWorkerSession worker_session(worker_id);
1082 ShenandoahEvacOOMScope oom_evac_scope;
1083 ShenandoahEvacuateUpdateRootsClosure<> cl;
1084 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1085 _rp->roots_do(worker_id, &cl);
1086 }
1087 };
1088
1089 void ShenandoahHeap::evacuate_and_update_roots() {
1090 #if COMPILER2_OR_JVMCI
1091 DerivedPointerTable::clear();
1092 #endif
1093 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1094 {
1095 // Include concurrent roots if current cycle can not process those roots concurrently
1096 ShenandoahRootEvacuator rp(workers()->active_workers(),
1097 ShenandoahPhaseTimings::init_evac,
1098 !ShenandoahConcurrentRoots::should_do_concurrent_roots(),
1099 !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
1100 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1101 workers()->run_task(&roots_task);
1102 }
1103
1104 #if COMPILER2_OR_JVMCI
1105 DerivedPointerTable::update_pointers();
1106 #endif
1107 }
1108
1109 // Returns size in bytes
1110 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1111 if (ShenandoahElasticTLAB) {
1112 // With Elastic TLABs, return the max allowed size, and let the allocation path
1113 // figure out the safe size for current allocation.
1114 return ShenandoahHeapRegion::max_tlab_size_bytes();
1115 } else {
1116 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1117 }
1118 }
1119
1120 size_t ShenandoahHeap::max_tlab_size() const {
1121 // Returns size in words
1122 return ShenandoahHeapRegion::max_tlab_size_words();
1123 }
1124
1125 class ShenandoahRetireAndResetGCLABClosure : public ThreadClosure {
1126 public:
1127 void do_thread(Thread* thread) {
1128 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1129 gclab->retire();
1130 if (ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1131 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1132 }
1133 }
1134 };
1135
1136 void ShenandoahHeap::retire_and_reset_gclabs() {
1137 ShenandoahRetireAndResetGCLABClosure cl;
1138 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1139 cl.do_thread(t);
1140 }
1141 workers()->threads_do(&cl);
1142 }
1143
1144 void ShenandoahHeap::collect(GCCause::Cause cause) {
1145 control_thread()->request_gc(cause);
1146 }
1147
1148 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1149 //assert(false, "Shouldn't need to do full collections");
1150 }
1151
1152 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1153 ShenandoahHeapRegion* r = heap_region_containing(addr);
1154 if (r != NULL) {
1155 return r->block_start(addr);
1156 }
1157 return NULL;
1158 }
1159
1160 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1161 ShenandoahHeapRegion* r = heap_region_containing(addr);
1162 return r->block_is_obj(addr);
1163 }
1164
1165 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1166 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1167 }
1168
1169 jlong ShenandoahHeap::millis_since_last_gc() {
1170 double v = heuristics()->time_since_last_gc() * 1000;
1171 assert(0 <= v && v <= max_jlong, "value should fit: %f", v);
1172 return (jlong)v;
1173 }
1174
1175 void ShenandoahHeap::prepare_for_verify() {
1176 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1177 make_parsable(false);
1178 }
1179 }
1180
1181 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1182 workers()->print_worker_threads_on(st);
1183 if (ShenandoahStringDedup::is_enabled()) {
1184 ShenandoahStringDedup::print_worker_threads_on(st);
1185 }
1186 }
1187
1188 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1189 workers()->threads_do(tcl);
1190 if (_safepoint_workers != NULL) {
1191 _safepoint_workers->threads_do(tcl);
1192 }
1193 if (ShenandoahStringDedup::is_enabled()) {
1194 ShenandoahStringDedup::threads_do(tcl);
1195 }
1196 }
1197
1198 void ShenandoahHeap::print_tracing_info() const {
1199 LogTarget(Info, gc, stats) lt;
1200 if (lt.is_enabled()) {
1201 ResourceMark rm;
1202 LogStream ls(lt);
1203
1204 phase_timings()->print_global_on(&ls);
1205
1206 ls.cr();
1207 ls.cr();
1208
1209 shenandoah_policy()->print_gc_stats(&ls);
1210
1211 ls.cr();
1212 ls.cr();
1213
1214 if (ShenandoahPacing) {
1215 pacer()->print_on(&ls);
1216 }
1217
1218 ls.cr();
1219 ls.cr();
1220 }
1221 }
1222
1223 void ShenandoahHeap::verify(VerifyOption vo) {
1224 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1225 if (ShenandoahVerify) {
1226 verifier()->verify_generic(vo);
1227 } else {
1228 // TODO: Consider allocating verification bitmaps on demand,
1229 // and turn this on unconditionally.
1230 }
1231 }
1232 }
1233 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1234 return _free_set->capacity();
1235 }
1236
1237 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1238 private:
1239 MarkBitMap* _bitmap;
1240 Stack<oop,mtGC>* _oop_stack;
1241 ShenandoahHeap* const _heap;
1242 ShenandoahMarkingContext* const _marking_context;
1243
1244 template <class T>
1245 void do_oop_work(T* p) {
1246 T o = RawAccess<>::oop_load(p);
1247 if (!CompressedOops::is_null(o)) {
1248 oop obj = CompressedOops::decode_not_null(o);
1249 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1250 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1251 return;
1252 }
1253 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1254
1255 assert(oopDesc::is_oop(obj), "must be a valid oop");
1256 if (!_bitmap->is_marked(obj)) {
1257 _bitmap->mark(obj);
1258 _oop_stack->push(obj);
1259 }
1260 }
1261 }
1262 public:
1263 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1264 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1265 _marking_context(_heap->marking_context()) {}
1266 void do_oop(oop* p) { do_oop_work(p); }
1267 void do_oop(narrowOop* p) { do_oop_work(p); }
1268 };
1269
1270 /*
1271 * This is public API, used in preparation of object_iterate().
1272 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1273 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1274 * control, we call SH::make_tlabs_parsable().
1275 */
1276 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1277 // No-op.
1278 }
1279
1280 /*
1281 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1282 *
1283 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1284 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1285 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1286 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1287 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1288 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1289 * wiped the bitmap in preparation for next marking).
1290 *
1291 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1292 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1293 * is allowed to report dead objects, but is not required to do so.
1294 */
1295 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1296 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1297 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1298 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1299 return;
1300 }
1301
1302 // Reset bitmap
1303 _aux_bit_map.clear();
1304
1305 Stack<oop,mtGC> oop_stack;
1306
1307 // First, we process GC roots according to current GC cycle. This populates the work stack with initial objects.
1308 ShenandoahHeapIterationRootScanner rp;
1309 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1310
1311 rp.roots_do(&oops);
1312
1313 // Work through the oop stack to traverse heap.
1314 while (! oop_stack.is_empty()) {
1315 oop obj = oop_stack.pop();
1316 assert(oopDesc::is_oop(obj), "must be a valid oop");
1317 cl->do_object(obj);
1318 obj->oop_iterate(&oops);
1319 }
1320
1321 assert(oop_stack.is_empty(), "should be empty");
1322
1323 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1324 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1325 }
1326 }
1327
1328 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1329 void ShenandoahHeap::keep_alive(oop obj) {
1330 if (is_concurrent_mark_in_progress()) {
1331 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1332 }
1333 }
1334
1335 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1336 for (size_t i = 0; i < num_regions(); i++) {
1337 ShenandoahHeapRegion* current = get_region(i);
1338 blk->heap_region_do(current);
1339 }
1340 }
1341
1342 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1343 private:
1344 ShenandoahHeap* const _heap;
1345 ShenandoahHeapRegionClosure* const _blk;
1346
1347 shenandoah_padding(0);
1348 volatile size_t _index;
1349 shenandoah_padding(1);
1350
1351 public:
1352 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1353 AbstractGangTask("Parallel Region Task"),
1354 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1355
1356 void work(uint worker_id) {
1357 ShenandoahParallelWorkerSession worker_session(worker_id);
1358 size_t stride = ShenandoahParallelRegionStride;
1359
1360 size_t max = _heap->num_regions();
1361 while (_index < max) {
1362 size_t cur = Atomic::fetch_and_add(&_index, stride);
1363 size_t start = cur;
1364 size_t end = MIN2(cur + stride, max);
1365 if (start >= max) break;
1366
1367 for (size_t i = cur; i < end; i++) {
1368 ShenandoahHeapRegion* current = _heap->get_region(i);
1369 _blk->heap_region_do(current);
1370 }
1371 }
1372 }
1373 };
1374
1375 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1376 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1377 if (num_regions() > ShenandoahParallelRegionStride) {
1378 ShenandoahParallelHeapRegionTask task(blk);
1379 workers()->run_task(&task);
1380 } else {
1381 heap_region_iterate(blk);
1382 }
1383 }
1384
1385 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1386 private:
1387 ShenandoahMarkingContext* const _ctx;
1388 public:
1389 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1390
1391 void heap_region_do(ShenandoahHeapRegion* r) {
1392 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1393 if (r->is_active()) {
1394 // Check if region needs updating its TAMS. We have updated it already during concurrent
1395 // reset, so it is very likely we don't need to do another write here.
1396 if (_ctx->top_at_mark_start(r) != r->top()) {
1397 _ctx->capture_top_at_mark_start(r);
1398 }
1399 } else {
1400 assert(_ctx->top_at_mark_start(r) == r->top(),
1401 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1402 }
1403 }
1404
1405 bool is_thread_safe() { return true; }
1406 };
1407
1408 void ShenandoahHeap::op_init_mark() {
1409 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1410 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1411
1412 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1413 assert(!marking_context()->is_complete(), "should not be complete");
1414 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1415
1416 if (ShenandoahVerify) {
1417 verifier()->verify_before_concmark();
1418 }
1419
1420 if (VerifyBeforeGC) {
1421 Universe::verify();
1422 }
1423
1424 set_concurrent_mark_in_progress(true);
1425 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1426 {
1427 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1428 make_parsable(true);
1429 }
1430
1431 {
1432 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_region_states);
1433 ShenandoahInitMarkUpdateRegionStateClosure cl;
1434 parallel_heap_region_iterate(&cl);
1435 }
1436
1437 // Make above changes visible to worker threads
1438 OrderAccess::fence();
1439
1440 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1441
1442 if (UseTLAB) {
1443 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1444 resize_tlabs();
1445 }
1446
1447 if (ShenandoahPacing) {
1448 pacer()->setup_for_mark();
1449 }
1450
1451 // Arm nmethods for concurrent marking. When a nmethod is about to be executed,
1452 // we need to make sure that all its metadata are marked. alternative is to remark
1453 // thread roots at final mark pause, but it can be potential latency killer.
1454 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1455 ShenandoahCodeRoots::arm_nmethods();
1456 }
1457 }
1458
1459 void ShenandoahHeap::op_mark() {
1460 concurrent_mark()->mark_from_roots();
1461 }
1462
1463 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1464 private:
1465 ShenandoahMarkingContext* const _ctx;
1466 ShenandoahHeapLock* const _lock;
1467
1468 public:
1469 ShenandoahFinalMarkUpdateRegionStateClosure() :
1470 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1471
1472 void heap_region_do(ShenandoahHeapRegion* r) {
1473 if (r->is_active()) {
1474 // All allocations past TAMS are implicitly live, adjust the region data.
1475 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1476 HeapWord *tams = _ctx->top_at_mark_start(r);
1477 HeapWord *top = r->top();
1478 if (top > tams) {
1479 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1480 }
1481
1482 // We are about to select the collection set, make sure it knows about
1483 // current pinning status. Also, this allows trashing more regions that
1484 // now have their pinning status dropped.
1485 if (r->is_pinned()) {
1486 if (r->pin_count() == 0) {
1487 ShenandoahHeapLocker locker(_lock);
1488 r->make_unpinned();
1489 }
1490 } else {
1491 if (r->pin_count() > 0) {
1492 ShenandoahHeapLocker locker(_lock);
1493 r->make_pinned();
1494 }
1495 }
1496
1497 // Remember limit for updating refs. It's guaranteed that we get no
1498 // from-space-refs written from here on.
1499 r->set_update_watermark_at_safepoint(r->top());
1500 } else {
1501 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1502 assert(_ctx->top_at_mark_start(r) == r->top(),
1503 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1504 }
1505 }
1506
1507 bool is_thread_safe() { return true; }
1508 };
1509
1510 void ShenandoahHeap::op_final_mark() {
1511 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1512 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1513
1514 // It is critical that we
1515 // evacuate roots right after finishing marking, so that we don't
1516 // get unmarked objects in the roots.
1517
1518 if (!cancelled_gc()) {
1519 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1520
1521 // Marking is completed, deactivate SATB barrier
1522 set_concurrent_mark_in_progress(false);
1523 mark_complete_marking_context();
1524
1525 parallel_cleaning(false /* full gc*/);
1526
1527 if (ShenandoahVerify) {
1528 verifier()->verify_roots_no_forwarded();
1529 }
1530
1531 {
1532 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_region_states);
1533 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1534 parallel_heap_region_iterate(&cl);
1535
1536 assert_pinned_region_status();
1537 }
1538
1539 // Retire the TLABs, which will force threads to reacquire their TLABs after the pause.
1540 // This is needed for two reasons. Strong one: new allocations would be with new freeset,
1541 // which would be outside the collection set, so no cset writes would happen there.
1542 // Weaker one: new allocations would happen past update watermark, and so less work would
1543 // be needed for reference updates (would update the large filler instead).
1544 {
1545 ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs);
1546 make_parsable(true);
1547 }
1548
1549 {
1550 ShenandoahGCPhase phase(ShenandoahPhaseTimings::choose_cset);
1551 ShenandoahHeapLocker locker(lock());
1552 _collection_set->clear();
1553 heuristics()->choose_collection_set(_collection_set);
1554 }
1555
1556 {
1557 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_rebuild_freeset);
1558 ShenandoahHeapLocker locker(lock());
1559 _free_set->rebuild();
1560 }
1561
1562 if (!is_degenerated_gc_in_progress()) {
1563 prepare_concurrent_roots();
1564 prepare_concurrent_unloading();
1565 }
1566
1567 // If collection set has candidates, start evacuation.
1568 // Otherwise, bypass the rest of the cycle.
1569 if (!collection_set()->is_empty()) {
1570 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1571
1572 if (ShenandoahVerify) {
1573 verifier()->verify_before_evacuation();
1574 }
1575
1576 set_evacuation_in_progress(true);
1577 // From here on, we need to update references.
1578 set_has_forwarded_objects(true);
1579
1580 if (!is_degenerated_gc_in_progress()) {
1581 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1582 ShenandoahCodeRoots::arm_nmethods();
1583 }
1584 evacuate_and_update_roots();
1585 }
1586
1587 if (ShenandoahPacing) {
1588 pacer()->setup_for_evac();
1589 }
1590
1591 if (ShenandoahVerify) {
1592 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::None;
1593 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1594 types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots);
1595 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots);
1596 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::StringDedupRoots);
1597 }
1598
1599 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1600 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CodeRoots);
1601 }
1602 verifier()->verify_roots_no_forwarded_except(types);
1603 verifier()->verify_during_evacuation();
1604 }
1605 } else {
1606 if (ShenandoahVerify) {
1607 verifier()->verify_after_concmark();
1608 }
1609
1610 if (VerifyAfterGC) {
1611 Universe::verify();
1612 }
1613 }
1614
1615 } else {
1616 // If this cycle was updating references, we need to keep the has_forwarded_objects
1617 // flag on, for subsequent phases to deal with it.
1618 concurrent_mark()->cancel();
1619 set_concurrent_mark_in_progress(false);
1620
1621 if (process_references()) {
1622 // Abandon reference processing right away: pre-cleaning must have failed.
1623 ReferenceProcessor *rp = ref_processor();
1624 rp->disable_discovery();
1625 rp->abandon_partial_discovery();
1626 rp->verify_no_references_recorded();
1627 }
1628 }
1629 }
1630
1631 void ShenandoahHeap::op_conc_evac() {
1632 ShenandoahEvacuationTask task(this, _collection_set, true);
1633 workers()->run_task(&task);
1634 }
1635
1636 void ShenandoahHeap::op_stw_evac() {
1637 ShenandoahEvacuationTask task(this, _collection_set, false);
1638 workers()->run_task(&task);
1639 }
1640
1641 void ShenandoahHeap::op_updaterefs() {
1642 update_heap_references(true);
1643 }
1644
1645 void ShenandoahHeap::op_cleanup_early() {
1646 free_set()->recycle_trash();
1647 }
1648
1649 void ShenandoahHeap::op_cleanup_complete() {
1650 free_set()->recycle_trash();
1651 }
1652
1653 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask {
1654 private:
1655 ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
1656 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots;
1657 ShenandoahConcurrentStringDedupRoots _dedup_roots;
1658
1659 public:
1660 ShenandoahConcurrentRootsEvacUpdateTask(ShenandoahPhaseTimings::Phase phase) :
1661 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Strong Roots Task"),
1662 _vm_roots(phase),
1663 _cld_roots(phase) {}
1664
1665 void work(uint worker_id) {
1666 ShenandoahConcurrentWorkerSession worker_session(worker_id);
1667 ShenandoahEvacOOMScope oom;
1668 {
1669 // vm_roots and weak_roots are OopStorage backed roots, concurrent iteration
1670 // may race against OopStorage::release() calls.
1671 ShenandoahEvacUpdateOopStorageRootsClosure cl;
1672 _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl, worker_id);
1673 }
1674
1675 {
1676 ShenandoahEvacuateUpdateRootsClosure<> cl;
1677 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1678 _cld_roots.cld_do(&clds, worker_id);
1679 }
1680
1681 {
1682 ShenandoahForwardedIsAliveClosure is_alive;
1683 ShenandoahEvacuateUpdateRootsClosure<MO_RELEASE> keep_alive;
1684 _dedup_roots.oops_do(&is_alive, &keep_alive, worker_id);
1685 }
1686 }
1687 };
1688
1689 class ShenandoahEvacUpdateCleanupOopStorageRootsClosure : public BasicOopIterateClosure {
1690 private:
1691 ShenandoahHeap* const _heap;
1692 ShenandoahMarkingContext* const _mark_context;
1693 bool _evac_in_progress;
1694 Thread* const _thread;
1695 size_t _dead_counter;
1696
1697 public:
1698 ShenandoahEvacUpdateCleanupOopStorageRootsClosure();
1699 void do_oop(oop* p);
1700 void do_oop(narrowOop* p);
1701
1702 size_t dead_counter() const;
1703 void reset_dead_counter();
1704 };
1705
1706 ShenandoahEvacUpdateCleanupOopStorageRootsClosure::ShenandoahEvacUpdateCleanupOopStorageRootsClosure() :
1707 _heap(ShenandoahHeap::heap()),
1708 _mark_context(ShenandoahHeap::heap()->marking_context()),
1709 _evac_in_progress(ShenandoahHeap::heap()->is_evacuation_in_progress()),
1710 _thread(Thread::current()),
1711 _dead_counter(0) {
1712 }
1713
1714 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(oop* p) {
1715 const oop obj = RawAccess<>::oop_load(p);
1716 if (!CompressedOops::is_null(obj)) {
1717 if (!_mark_context->is_marked(obj)) {
1718 shenandoah_assert_correct(p, obj);
1719 oop old = Atomic::cmpxchg(p, obj, oop(NULL));
1720 if (obj == old) {
1721 _dead_counter ++;
1722 }
1723 } else if (_evac_in_progress && _heap->in_collection_set(obj)) {
1724 oop resolved = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1725 if (resolved == obj) {
1726 resolved = _heap->evacuate_object(obj, _thread);
1727 }
1728 Atomic::cmpxchg(p, obj, resolved);
1729 assert(_heap->cancelled_gc() ||
1730 _mark_context->is_marked(resolved) && !_heap->in_collection_set(resolved),
1731 "Sanity");
1732 }
1733 }
1734 }
1735
1736 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(narrowOop* p) {
1737 ShouldNotReachHere();
1738 }
1739
1740 size_t ShenandoahEvacUpdateCleanupOopStorageRootsClosure::dead_counter() const {
1741 return _dead_counter;
1742 }
1743
1744 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::reset_dead_counter() {
1745 _dead_counter = 0;
1746 }
1747
1748 class ShenandoahIsCLDAliveClosure : public CLDClosure {
1749 public:
1750 void do_cld(ClassLoaderData* cld) {
1751 cld->is_alive();
1752 }
1753 };
1754
1755 class ShenandoahIsNMethodAliveClosure: public NMethodClosure {
1756 public:
1757 void do_nmethod(nmethod* n) {
1758 n->is_unloading();
1759 }
1760 };
1761
1762 // This task not only evacuates/updates marked weak roots, but also "NULL"
1763 // dead weak roots.
1764 class ShenandoahConcurrentWeakRootsEvacUpdateTask : public AbstractGangTask {
1765 private:
1766 ShenandoahWeakRoot<true /*concurrent*/> _jni_roots;
1767 ShenandoahWeakRoot<true /*concurrent*/> _string_table_roots;
1768 ShenandoahWeakRoot<true /*concurrent*/> _resolved_method_table_roots;
1769 ShenandoahWeakRoot<true /*concurrent*/> _vm_roots;
1770
1771 // Roots related to concurrent class unloading
1772 ShenandoahClassLoaderDataRoots<true /* concurrent */, false /* single thread*/>
1773 _cld_roots;
1774 ShenandoahConcurrentNMethodIterator _nmethod_itr;
1775 bool _concurrent_class_unloading;
1776
1777 public:
1778 ShenandoahConcurrentWeakRootsEvacUpdateTask(ShenandoahPhaseTimings::Phase phase) :
1779 AbstractGangTask("Shenandoah Concurrent Weak Root Task"),
1780 _jni_roots(OopStorageSet::jni_weak(), phase, ShenandoahPhaseTimings::JNIWeakRoots),
1781 _string_table_roots(OopStorageSet::string_table_weak(), phase, ShenandoahPhaseTimings::StringTableRoots),
1782 _resolved_method_table_roots(OopStorageSet::resolved_method_table_weak(), phase, ShenandoahPhaseTimings::ResolvedMethodTableRoots),
1783 _vm_roots(OopStorageSet::vm_weak(), phase, ShenandoahPhaseTimings::VMWeakRoots),
1784 _cld_roots(phase),
1785 _nmethod_itr(ShenandoahCodeRoots::table()),
1786 _concurrent_class_unloading(ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1787 StringTable::reset_dead_counter();
1788 ResolvedMethodTable::reset_dead_counter();
1789 if (_concurrent_class_unloading) {
1790 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
1791 _nmethod_itr.nmethods_do_begin();
1792 }
1793 }
1794
1795 ~ShenandoahConcurrentWeakRootsEvacUpdateTask() {
1796 StringTable::finish_dead_counter();
1797 ResolvedMethodTable::finish_dead_counter();
1798 if (_concurrent_class_unloading) {
1799 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
1800 _nmethod_itr.nmethods_do_end();
1801 }
1802 }
1803
1804 void work(uint worker_id) {
1805 ShenandoahConcurrentWorkerSession worker_session(worker_id);
1806 {
1807 ShenandoahEvacOOMScope oom;
1808 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
1809 // may race against OopStorage::release() calls.
1810 ShenandoahEvacUpdateCleanupOopStorageRootsClosure cl;
1811 _jni_roots.oops_do(&cl, worker_id);
1812 _vm_roots.oops_do(&cl, worker_id);
1813
1814 cl.reset_dead_counter();
1815 _string_table_roots.oops_do(&cl, worker_id);
1816 StringTable::inc_dead_counter(cl.dead_counter());
1817
1818 cl.reset_dead_counter();
1819 _resolved_method_table_roots.oops_do(&cl, worker_id);
1820 ResolvedMethodTable::inc_dead_counter(cl.dead_counter());
1821 }
1822
1823 // If we are going to perform concurrent class unloading later on, we need to
1824 // cleanup the weak oops in CLD and determinate nmethod's unloading state, so that we
1825 // can cleanup immediate garbage sooner.
1826 if (_concurrent_class_unloading) {
1827 // Applies ShenandoahIsCLDAlive closure to CLDs, native barrier will either NULL the
1828 // CLD's holder or evacuate it.
1829 ShenandoahIsCLDAliveClosure is_cld_alive;
1830 _cld_roots.cld_do(&is_cld_alive, worker_id);
1831
1832 // Applies ShenandoahIsNMethodAliveClosure to registered nmethods.
1833 // The closure calls nmethod->is_unloading(). The is_unloading
1834 // state is cached, therefore, during concurrent class unloading phase,
1835 // we will not touch the metadata of unloading nmethods
1836 ShenandoahIsNMethodAliveClosure is_nmethod_alive;
1837 _nmethod_itr.nmethods_do(&is_nmethod_alive);
1838 }
1839 }
1840 };
1841
1842 void ShenandoahHeap::op_weak_roots() {
1843 if (is_concurrent_weak_root_in_progress()) {
1844 // Concurrent weak root processing
1845 {
1846 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_weak_roots_work);
1847 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_weak_roots_work);
1848 ShenandoahConcurrentWeakRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_weak_roots_work);
1849 workers()->run_task(&task);
1850 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1851 set_concurrent_weak_root_in_progress(false);
1852 }
1853 }
1854
1855 // Perform handshake to flush out dead oops
1856 {
1857 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_weak_roots_rendezvous);
1858 ShenandoahRendezvousClosure cl;
1859 Handshake::execute(&cl);
1860 }
1861 }
1862 }
1863
1864 void ShenandoahHeap::op_class_unloading() {
1865 assert (is_concurrent_weak_root_in_progress() &&
1866 ShenandoahConcurrentRoots::should_do_concurrent_class_unloading(),
1867 "Checked by caller");
1868 _unloader.unload();
1869 set_concurrent_weak_root_in_progress(false);
1870 }
1871
1872 void ShenandoahHeap::op_strong_roots() {
1873 assert(is_concurrent_strong_root_in_progress(), "Checked by caller");
1874 ShenandoahConcurrentRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_strong_roots);
1875 workers()->run_task(&task);
1876 set_concurrent_strong_root_in_progress(false);
1877 }
1878
1879 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1880 private:
1881 ShenandoahMarkingContext* const _ctx;
1882 public:
1883 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1884
1885 void heap_region_do(ShenandoahHeapRegion* r) {
1886 if (r->is_active()) {
1887 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1888 // anyway to capture any updates that happened since now.
1889 r->clear_live_data();
1890 _ctx->capture_top_at_mark_start(r);
1891 }
1892 }
1893
1894 bool is_thread_safe() { return true; }
1895 };
1896
1897 void ShenandoahHeap::op_reset() {
1898 if (ShenandoahPacing) {
1899 pacer()->setup_for_reset();
1900 }
1901 reset_mark_bitmap();
1902
1903 ShenandoahResetUpdateRegionStateClosure cl;
1904 parallel_heap_region_iterate(&cl);
1905 }
1906
1907 void ShenandoahHeap::op_preclean() {
1908 if (ShenandoahPacing) {
1909 pacer()->setup_for_preclean();
1910 }
1911 concurrent_mark()->preclean_weak_refs();
1912 }
1913
1914 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1915 ShenandoahMetricsSnapshot metrics;
1916 metrics.snap_before();
1917
1918 full_gc()->do_it(cause);
1919 if (UseTLAB) {
1920 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs);
1921 resize_all_tlabs();
1922 }
1923
1924 metrics.snap_after();
1925
1926 if (metrics.is_good_progress()) {
1927 _progress_last_gc.set();
1928 } else {
1929 // Nothing to do. Tell the allocation path that we have failed to make
1930 // progress, and it can finally fail.
1931 _progress_last_gc.unset();
1932 }
1933 }
1934
1935 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1936 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1937 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1938 // some phase, we have to upgrade the Degenerate GC to Full GC.
1939
1940 clear_cancelled_gc();
1941
1942 ShenandoahMetricsSnapshot metrics;
1943 metrics.snap_before();
1944
1945 switch (point) {
1946 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1947 // but enters it at different points, depending on which concurrent phase had
1948 // degenerated.
1949
1950 case _degenerated_outside_cycle:
1951 // We have degenerated from outside the cycle, which means something is bad with
1952 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1953 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1954 // we can do the most aggressive degen cycle, which includes processing references and
1955 // class unloading, unless those features are explicitly disabled.
1956 //
1957 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1958 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1959 set_process_references(heuristics()->can_process_references());
1960 set_unload_classes(heuristics()->can_unload_classes());
1961
1962 op_reset();
1963
1964 op_init_mark();
1965 if (cancelled_gc()) {
1966 op_degenerated_fail();
1967 return;
1968 }
1969
1970 case _degenerated_mark:
1971 op_final_mark();
1972 if (cancelled_gc()) {
1973 op_degenerated_fail();
1974 return;
1975 }
1976
1977 if (!has_forwarded_objects() && ShenandoahConcurrentRoots::can_do_concurrent_class_unloading()) {
1978 // Disarm nmethods that armed for concurrent mark. On normal cycle, it would
1979 // be disarmed while conc-roots phase is running.
1980 // TODO: Call op_conc_roots() here instead
1981 ShenandoahCodeRoots::disarm_nmethods();
1982 }
1983
1984 op_cleanup_early();
1985
1986 case _degenerated_evac:
1987 // If heuristics thinks we should do the cycle, this flag would be set,
1988 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
1989 if (is_evacuation_in_progress()) {
1990
1991 // Degeneration under oom-evac protocol might have left some objects in
1992 // collection set un-evacuated. Restart evacuation from the beginning to
1993 // capture all objects. For all the objects that are already evacuated,
1994 // it would be a simple check, which is supposed to be fast. This is also
1995 // safe to do even without degeneration, as CSet iterator is at beginning
1996 // in preparation for evacuation anyway.
1997 //
1998 // Before doing that, we need to make sure we never had any cset-pinned
1999 // regions. This may happen if allocation failure happened when evacuating
2000 // the about-to-be-pinned object, oom-evac protocol left the object in
2001 // the collection set, and then the pin reached the cset region. If we continue
2002 // the cycle here, we would trash the cset and alive objects in it. To avoid
2003 // it, we fail degeneration right away and slide into Full GC to recover.
2004
2005 {
2006 sync_pinned_region_status();
2007 collection_set()->clear_current_index();
2008
2009 ShenandoahHeapRegion* r;
2010 while ((r = collection_set()->next()) != NULL) {
2011 if (r->is_pinned()) {
2012 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
2013 op_degenerated_fail();
2014 return;
2015 }
2016 }
2017
2018 collection_set()->clear_current_index();
2019 }
2020
2021 op_stw_evac();
2022 if (cancelled_gc()) {
2023 op_degenerated_fail();
2024 return;
2025 }
2026 }
2027
2028 // If heuristics thinks we should do the cycle, this flag would be set,
2029 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
2030 if (has_forwarded_objects()) {
2031 op_init_updaterefs();
2032 if (cancelled_gc()) {
2033 op_degenerated_fail();
2034 return;
2035 }
2036 }
2037
2038 case _degenerated_updaterefs:
2039 if (has_forwarded_objects()) {
2040 op_final_updaterefs();
2041 if (cancelled_gc()) {
2042 op_degenerated_fail();
2043 return;
2044 }
2045 }
2046
2047 op_cleanup_complete();
2048 break;
2049
2050 default:
2051 ShouldNotReachHere();
2052 }
2053
2054 if (ShenandoahVerify) {
2055 verifier()->verify_after_degenerated();
2056 }
2057
2058 if (VerifyAfterGC) {
2059 Universe::verify();
2060 }
2061
2062 metrics.snap_after();
2063
2064 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
2065 // because that probably means the heap is overloaded and/or fragmented.
2066 if (!metrics.is_good_progress()) {
2067 _progress_last_gc.unset();
2068 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
2069 op_degenerated_futile();
2070 } else {
2071 _progress_last_gc.set();
2072 }
2073 }
2074
2075 void ShenandoahHeap::op_degenerated_fail() {
2076 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
2077 shenandoah_policy()->record_degenerated_upgrade_to_full();
2078 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2079 }
2080
2081 void ShenandoahHeap::op_degenerated_futile() {
2082 shenandoah_policy()->record_degenerated_upgrade_to_full();
2083 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2084 }
2085
2086 void ShenandoahHeap::force_satb_flush_all_threads() {
2087 if (!is_concurrent_mark_in_progress()) {
2088 // No need to flush SATBs
2089 return;
2090 }
2091
2092 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2093 ShenandoahThreadLocalData::set_force_satb_flush(t, true);
2094 }
2095 // The threads are not "acquiring" their thread-local data, but it does not
2096 // hurt to "release" the updates here anyway.
2097 OrderAccess::fence();
2098 }
2099
2100 void ShenandoahHeap::set_gc_state_all_threads(char state) {
2101 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2102 ShenandoahThreadLocalData::set_gc_state(t, state);
2103 }
2104 }
2105
2106 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
2107 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
2108 _gc_state.set_cond(mask, value);
2109 set_gc_state_all_threads(_gc_state.raw_value());
2110 }
2111
2112 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
2113 if (has_forwarded_objects()) {
2114 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
2115 } else {
2116 set_gc_state_mask(MARKING, in_progress);
2117 }
2118 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
2119 }
2120
2121 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
2122 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
2123 set_gc_state_mask(EVACUATION, in_progress);
2124 }
2125
2126 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
2127 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
2128 if (in_progress) {
2129 _concurrent_strong_root_in_progress.set();
2130 } else {
2131 _concurrent_strong_root_in_progress.unset();
2132 }
2133 }
2134
2135 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool in_progress) {
2136 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
2137 if (in_progress) {
2138 _concurrent_weak_root_in_progress.set();
2139 } else {
2140 _concurrent_weak_root_in_progress.unset();
2141 }
2142 }
2143
2144 void ShenandoahHeap::ref_processing_init() {
2145 assert(_max_workers > 0, "Sanity");
2146
2147 _ref_processor =
2148 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
2149 _ref_proc_mt_processing, // MT processing
2150 _max_workers, // Degree of MT processing
2151 _ref_proc_mt_discovery, // MT discovery
2152 _max_workers, // Degree of MT discovery
2153 false, // Reference discovery is not atomic
2154 NULL, // No closure, should be installed before use
2155 true); // Scale worker threads
2156
2157 shenandoah_assert_rp_isalive_not_installed();
2158 }
2159
2160 GCTracer* ShenandoahHeap::tracer() {
2161 return shenandoah_policy()->tracer();
2162 }
2163
2164 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
2165 return _free_set->used();
2166 }
2167
2168 bool ShenandoahHeap::try_cancel_gc() {
2169 while (true) {
2170 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
2171 if (prev == CANCELLABLE) return true;
2172 else if (prev == CANCELLED) return false;
2173 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
2174 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
2175 if (Thread::current()->is_Java_thread()) {
2176 // We need to provide a safepoint here, otherwise we might
2177 // spin forever if a SP is pending.
2178 ThreadBlockInVM sp(JavaThread::current());
2179 SpinPause();
2180 }
2181 }
2182 }
2183
2184 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
2185 if (try_cancel_gc()) {
2186 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
2187 log_info(gc)("%s", msg.buffer());
2188 Events::log(Thread::current(), "%s", msg.buffer());
2189 }
2190 }
2191
2192 uint ShenandoahHeap::max_workers() {
2193 return _max_workers;
2194 }
2195
2196 void ShenandoahHeap::stop() {
2197 // The shutdown sequence should be able to terminate when GC is running.
2198
2199 // Step 0. Notify policy to disable event recording.
2200 _shenandoah_policy->record_shutdown();
2201
2202 // Step 1. Notify control thread that we are in shutdown.
2203 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
2204 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
2205 control_thread()->prepare_for_graceful_shutdown();
2206
2207 // Step 2. Notify GC workers that we are cancelling GC.
2208 cancel_gc(GCCause::_shenandoah_stop_vm);
2209
2210 // Step 3. Wait until GC worker exits normally.
2211 control_thread()->stop();
2212
2213 // Step 4. Stop String Dedup thread if it is active
2214 if (ShenandoahStringDedup::is_enabled()) {
2215 ShenandoahStringDedup::stop();
2216 }
2217 }
2218
2219 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
2220 if (!unload_classes()) return;
2221
2222 // Unload classes and purge SystemDictionary.
2223 {
2224 ShenandoahGCPhase phase(full_gc ?
2225 ShenandoahPhaseTimings::full_gc_purge_class_unload :
2226 ShenandoahPhaseTimings::purge_class_unload);
2227 bool purged_class = SystemDictionary::do_unloading(gc_timer());
2228
2229 ShenandoahIsAliveSelector is_alive;
2230 uint num_workers = _workers->active_workers();
2231 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
2232 _workers->run_task(&unlink_task);
2233 }
2234
2235 {
2236 ShenandoahGCPhase phase(full_gc ?
2237 ShenandoahPhaseTimings::full_gc_purge_cldg :
2238 ShenandoahPhaseTimings::purge_cldg);
2239 ClassLoaderDataGraph::purge();
2240 }
2241 // Resize and verify metaspace
2242 MetaspaceGC::compute_new_size();
2243 MetaspaceUtils::verify_metrics();
2244 }
2245
2246 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
2247 // so they should not have forwarded oops.
2248 // However, we do need to "null" dead oops in the roots, if can not be done
2249 // in concurrent cycles.
2250 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
2251 ShenandoahGCPhase root_phase(full_gc ?
2252 ShenandoahPhaseTimings::full_gc_purge :
2253 ShenandoahPhaseTimings::purge);
2254 uint num_workers = _workers->active_workers();
2255 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
2256 ShenandoahPhaseTimings::full_gc_purge_weak_par :
2257 ShenandoahPhaseTimings::purge_weak_par;
2258 ShenandoahGCPhase phase(timing_phase);
2259 ShenandoahGCWorkerPhase worker_phase(timing_phase);
2260
2261 // Cleanup weak roots
2262 if (has_forwarded_objects()) {
2263 ShenandoahForwardedIsAliveClosure is_alive;
2264 ShenandoahUpdateRefsClosure keep_alive;
2265 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2266 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2267 _workers->run_task(&cleaning_task);
2268 } else {
2269 ShenandoahIsAliveClosure is_alive;
2270 #ifdef ASSERT
2271 ShenandoahAssertNotForwardedClosure verify_cl;
2272 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2273 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2274 #else
2275 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2276 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2277 #endif
2278 _workers->run_task(&cleaning_task);
2279 }
2280 }
2281
2282 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2283 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2284 stw_process_weak_roots(full_gc);
2285 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2286 stw_unload_classes(full_gc);
2287 }
2288 }
2289
2290 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2291 set_gc_state_mask(HAS_FORWARDED, cond);
2292 }
2293
2294 void ShenandoahHeap::set_process_references(bool pr) {
2295 _process_references.set_cond(pr);
2296 }
2297
2298 void ShenandoahHeap::set_unload_classes(bool uc) {
2299 _unload_classes.set_cond(uc);
2300 }
2301
2302 bool ShenandoahHeap::process_references() const {
2303 return _process_references.is_set();
2304 }
2305
2306 bool ShenandoahHeap::unload_classes() const {
2307 return _unload_classes.is_set();
2308 }
2309
2310 address ShenandoahHeap::in_cset_fast_test_addr() {
2311 ShenandoahHeap* heap = ShenandoahHeap::heap();
2312 assert(heap->collection_set() != NULL, "Sanity");
2313 return (address) heap->collection_set()->biased_map_address();
2314 }
2315
2316 address ShenandoahHeap::cancelled_gc_addr() {
2317 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
2318 }
2319
2320 address ShenandoahHeap::gc_state_addr() {
2321 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2322 }
2323
2324 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2325 return Atomic::load_acquire(&_bytes_allocated_since_gc_start);
2326 }
2327
2328 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2329 Atomic::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2330 }
2331
2332 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2333 _degenerated_gc_in_progress.set_cond(in_progress);
2334 }
2335
2336 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2337 _full_gc_in_progress.set_cond(in_progress);
2338 }
2339
2340 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2341 assert (is_full_gc_in_progress(), "should be");
2342 _full_gc_move_in_progress.set_cond(in_progress);
2343 }
2344
2345 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2346 set_gc_state_mask(UPDATEREFS, in_progress);
2347 }
2348
2349 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2350 ShenandoahCodeRoots::register_nmethod(nm);
2351 }
2352
2353 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2354 ShenandoahCodeRoots::unregister_nmethod(nm);
2355 }
2356
2357 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
2358 ShenandoahCodeRoots::flush_nmethod(nm);
2359 }
2360
2361 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2362 heap_region_containing(o)->record_pin();
2363 return o;
2364 }
2365
2366 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2367 heap_region_containing(o)->record_unpin();
2368 }
2369
2370 void ShenandoahHeap::sync_pinned_region_status() {
2371 ShenandoahHeapLocker locker(lock());
2372
2373 for (size_t i = 0; i < num_regions(); i++) {
2374 ShenandoahHeapRegion *r = get_region(i);
2375 if (r->is_active()) {
2376 if (r->is_pinned()) {
2377 if (r->pin_count() == 0) {
2378 r->make_unpinned();
2379 }
2380 } else {
2381 if (r->pin_count() > 0) {
2382 r->make_pinned();
2383 }
2384 }
2385 }
2386 }
2387
2388 assert_pinned_region_status();
2389 }
2390
2391 #ifdef ASSERT
2392 void ShenandoahHeap::assert_pinned_region_status() {
2393 for (size_t i = 0; i < num_regions(); i++) {
2394 ShenandoahHeapRegion* r = get_region(i);
2395 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2396 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2397 }
2398 }
2399 #endif
2400
2401 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
2402 return _gc_timer;
2403 }
2404
2405 void ShenandoahHeap::prepare_concurrent_roots() {
2406 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2407 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
2408 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
2409 set_concurrent_weak_root_in_progress(true);
2410 }
2411 }
2412
2413 void ShenandoahHeap::prepare_concurrent_unloading() {
2414 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2415 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2416 _unloader.prepare();
2417 }
2418 }
2419
2420 void ShenandoahHeap::finish_concurrent_unloading() {
2421 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2422 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2423 _unloader.finish();
2424 }
2425 }
2426
2427 #ifdef ASSERT
2428 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2429 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2430
2431 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2432 if (UseDynamicNumberOfGCThreads) {
2433 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2434 } else {
2435 // Use ParallelGCThreads inside safepoints
2436 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
2437 }
2438 } else {
2439 if (UseDynamicNumberOfGCThreads) {
2440 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2441 } else {
2442 // Use ConcGCThreads outside safepoints
2443 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2444 }
2445 }
2446 }
2447 #endif
2448
2449 ShenandoahVerifier* ShenandoahHeap::verifier() {
2450 guarantee(ShenandoahVerify, "Should be enabled");
2451 assert (_verifier != NULL, "sanity");
2452 return _verifier;
2453 }
2454
2455 template<class T>
2456 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2457 private:
2458 T cl;
2459 ShenandoahHeap* _heap;
2460 ShenandoahRegionIterator* _regions;
2461 bool _concurrent;
2462 public:
2463 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2464 AbstractGangTask("Concurrent Update References Task"),
2465 cl(T()),
2466 _heap(ShenandoahHeap::heap()),
2467 _regions(regions),
2468 _concurrent(concurrent) {
2469 }
2470
2471 void work(uint worker_id) {
2472 if (_concurrent) {
2473 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2474 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2475 do_work();
2476 } else {
2477 ShenandoahParallelWorkerSession worker_session(worker_id);
2478 do_work();
2479 }
2480 }
2481
2482 private:
2483 void do_work() {
2484 ShenandoahHeapRegion* r = _regions->next();
2485 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2486 while (r != NULL) {
2487 HeapWord* update_watermark = r->get_update_watermark();
2488 assert (update_watermark >= r->bottom(), "sanity");
2489 if (r->is_active() && !r->is_cset()) {
2490 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2491 }
2492 if (ShenandoahPacing) {
2493 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2494 }
2495 if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
2496 return;
2497 }
2498 r = _regions->next();
2499 }
2500 }
2501 };
2502
2503 void ShenandoahHeap::update_heap_references(bool concurrent) {
2504 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
2505 workers()->run_task(&task);
2506 }
2507
2508 void ShenandoahHeap::op_init_updaterefs() {
2509 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2510
2511 set_evacuation_in_progress(false);
2512
2513 {
2514 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_retire_gclabs);
2515 retire_and_reset_gclabs();
2516 }
2517
2518 if (ShenandoahVerify) {
2519 if (!is_degenerated_gc_in_progress()) {
2520 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2521 }
2522 verifier()->verify_before_updaterefs();
2523 }
2524
2525 set_update_refs_in_progress(true);
2526
2527 _update_refs_iterator.reset();
2528
2529 if (ShenandoahPacing) {
2530 pacer()->setup_for_updaterefs();
2531 }
2532 }
2533
2534 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2535 private:
2536 ShenandoahHeapLock* const _lock;
2537
2538 public:
2539 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2540
2541 void heap_region_do(ShenandoahHeapRegion* r) {
2542 // Drop unnecessary "pinned" state from regions that does not have CP marks
2543 // anymore, as this would allow trashing them.
2544
2545 if (r->is_active()) {
2546 if (r->is_pinned()) {
2547 if (r->pin_count() == 0) {
2548 ShenandoahHeapLocker locker(_lock);
2549 r->make_unpinned();
2550 }
2551 } else {
2552 if (r->pin_count() > 0) {
2553 ShenandoahHeapLocker locker(_lock);
2554 r->make_pinned();
2555 }
2556 }
2557 }
2558 }
2559
2560 bool is_thread_safe() { return true; }
2561 };
2562
2563 void ShenandoahHeap::op_final_updaterefs() {
2564 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2565
2566 finish_concurrent_unloading();
2567
2568 // Check if there is left-over work, and finish it
2569 if (_update_refs_iterator.has_next()) {
2570 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2571
2572 // Finish updating references where we left off.
2573 clear_cancelled_gc();
2574 update_heap_references(false);
2575 }
2576
2577 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2578 // everything. On degenerated paths, cancelled gc would not be set anyway.
2579 if (cancelled_gc()) {
2580 clear_cancelled_gc();
2581 }
2582 assert(!cancelled_gc(), "Should have been done right before");
2583
2584 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2585 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2586 }
2587
2588 if (is_degenerated_gc_in_progress()) {
2589 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2590 } else {
2591 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2592 }
2593
2594 // Has to be done before cset is clear
2595 if (ShenandoahVerify) {
2596 verifier()->verify_roots_in_to_space();
2597 }
2598
2599 {
2600 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_update_region_states);
2601 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2602 parallel_heap_region_iterate(&cl);
2603
2604 assert_pinned_region_status();
2605 }
2606
2607 {
2608 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2609 trash_cset_regions();
2610 }
2611
2612 set_has_forwarded_objects(false);
2613 set_update_refs_in_progress(false);
2614
2615 if (ShenandoahVerify) {
2616 verifier()->verify_after_updaterefs();
2617 }
2618
2619 if (VerifyAfterGC) {
2620 Universe::verify();
2621 }
2622
2623 {
2624 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_rebuild_freeset);
2625 ShenandoahHeapLocker locker(lock());
2626 _free_set->rebuild();
2627 }
2628 }
2629
2630 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2631 print_on(st);
2632 print_heap_regions_on(st);
2633 }
2634
2635 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2636 size_t slice = r->index() / _bitmap_regions_per_slice;
2637
2638 size_t regions_from = _bitmap_regions_per_slice * slice;
2639 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2640 for (size_t g = regions_from; g < regions_to; g++) {
2641 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2642 if (skip_self && g == r->index()) continue;
2643 if (get_region(g)->is_committed()) {
2644 return true;
2645 }
2646 }
2647 return false;
2648 }
2649
2650 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2651 shenandoah_assert_heaplocked();
2652
2653 // Bitmaps in special regions do not need commits
2654 if (_bitmap_region_special) {
2655 return true;
2656 }
2657
2658 if (is_bitmap_slice_committed(r, true)) {
2659 // Some other region from the group is already committed, meaning the bitmap
2660 // slice is already committed, we exit right away.
2661 return true;
2662 }
2663
2664 // Commit the bitmap slice:
2665 size_t slice = r->index() / _bitmap_regions_per_slice;
2666 size_t off = _bitmap_bytes_per_slice * slice;
2667 size_t len = _bitmap_bytes_per_slice;
2668 char* start = (char*) _bitmap_region.start() + off;
2669
2670 if (!os::commit_memory(start, len, false)) {
2671 return false;
2672 }
2673
2674 if (AlwaysPreTouch) {
2675 os::pretouch_memory(start, start + len, _pretouch_bitmap_page_size);
2676 }
2677
2678 return true;
2679 }
2680
2681 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2682 shenandoah_assert_heaplocked();
2683
2684 // Bitmaps in special regions do not need uncommits
2685 if (_bitmap_region_special) {
2686 return true;
2687 }
2688
2689 if (is_bitmap_slice_committed(r, true)) {
2690 // Some other region from the group is still committed, meaning the bitmap
2691 // slice is should stay committed, exit right away.
2692 return true;
2693 }
2694
2695 // Uncommit the bitmap slice:
2696 size_t slice = r->index() / _bitmap_regions_per_slice;
2697 size_t off = _bitmap_bytes_per_slice * slice;
2698 size_t len = _bitmap_bytes_per_slice;
2699 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2700 return false;
2701 }
2702 return true;
2703 }
2704
2705 void ShenandoahHeap::safepoint_synchronize_begin() {
2706 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2707 SuspendibleThreadSet::synchronize();
2708 }
2709 }
2710
2711 void ShenandoahHeap::safepoint_synchronize_end() {
2712 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2713 SuspendibleThreadSet::desynchronize();
2714 }
2715 }
2716
2717 void ShenandoahHeap::vmop_entry_init_mark() {
2718 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2719 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::init_mark_gross);
2720
2721 try_inject_alloc_failure();
2722 VM_ShenandoahInitMark op;
2723 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2724 }
2725
2726 void ShenandoahHeap::vmop_entry_final_mark() {
2727 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2728 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_mark_gross);
2729
2730 try_inject_alloc_failure();
2731 VM_ShenandoahFinalMarkStartEvac op;
2732 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2733 }
2734
2735 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2736 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2737 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::init_update_refs_gross);
2738
2739 try_inject_alloc_failure();
2740 VM_ShenandoahInitUpdateRefs op;
2741 VMThread::execute(&op);
2742 }
2743
2744 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2745 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2746 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_update_refs_gross);
2747
2748 try_inject_alloc_failure();
2749 VM_ShenandoahFinalUpdateRefs op;
2750 VMThread::execute(&op);
2751 }
2752
2753 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2754 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2755 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::full_gc_gross);
2756
2757 try_inject_alloc_failure();
2758 VM_ShenandoahFullGC op(cause);
2759 VMThread::execute(&op);
2760 }
2761
2762 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2763 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2764 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::degen_gc_gross);
2765
2766 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2767 VMThread::execute(°enerated_gc);
2768 }
2769
2770 void ShenandoahHeap::entry_init_mark() {
2771 const char* msg = init_mark_event_message();
2772 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::init_mark);
2773 EventMark em("%s", msg);
2774
2775 ShenandoahWorkerScope scope(workers(),
2776 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2777 "init marking");
2778
2779 op_init_mark();
2780 }
2781
2782 void ShenandoahHeap::entry_final_mark() {
2783 const char* msg = final_mark_event_message();
2784 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_mark);
2785 EventMark em("%s", msg);
2786
2787 ShenandoahWorkerScope scope(workers(),
2788 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2789 "final marking");
2790
2791 op_final_mark();
2792 }
2793
2794 void ShenandoahHeap::entry_init_updaterefs() {
2795 static const char* msg = "Pause Init Update Refs";
2796 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::init_update_refs);
2797 EventMark em("%s", msg);
2798
2799 // No workers used in this phase, no setup required
2800
2801 op_init_updaterefs();
2802 }
2803
2804 void ShenandoahHeap::entry_final_updaterefs() {
2805 static const char* msg = "Pause Final Update Refs";
2806 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_update_refs);
2807 EventMark em("%s", msg);
2808
2809 ShenandoahWorkerScope scope(workers(),
2810 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2811 "final reference update");
2812
2813 op_final_updaterefs();
2814 }
2815
2816 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2817 static const char* msg = "Pause Full";
2818 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::full_gc, true /* log_heap_usage */);
2819 EventMark em("%s", msg);
2820
2821 ShenandoahWorkerScope scope(workers(),
2822 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2823 "full gc");
2824
2825 op_full(cause);
2826 }
2827
2828 void ShenandoahHeap::entry_degenerated(int point) {
2829 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2830 const char* msg = degen_event_message(dpoint);
2831 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::degen_gc, true /* log_heap_usage */);
2832 EventMark em("%s", msg);
2833
2834 ShenandoahWorkerScope scope(workers(),
2835 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2836 "stw degenerated gc");
2837
2838 set_degenerated_gc_in_progress(true);
2839 op_degenerated(dpoint);
2840 set_degenerated_gc_in_progress(false);
2841 }
2842
2843 void ShenandoahHeap::entry_mark() {
2844 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2845
2846 const char* msg = conc_mark_event_message();
2847 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_mark);
2848 EventMark em("%s", msg);
2849
2850 ShenandoahWorkerScope scope(workers(),
2851 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2852 "concurrent marking");
2853
2854 try_inject_alloc_failure();
2855 op_mark();
2856 }
2857
2858 void ShenandoahHeap::entry_evac() {
2859 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2860
2861 static const char* msg = "Concurrent evacuation";
2862 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_evac);
2863 EventMark em("%s", msg);
2864
2865 ShenandoahWorkerScope scope(workers(),
2866 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2867 "concurrent evacuation");
2868
2869 try_inject_alloc_failure();
2870 op_conc_evac();
2871 }
2872
2873 void ShenandoahHeap::entry_updaterefs() {
2874 static const char* msg = "Concurrent update references";
2875 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_update_refs);
2876 EventMark em("%s", msg);
2877
2878 ShenandoahWorkerScope scope(workers(),
2879 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2880 "concurrent reference update");
2881
2882 try_inject_alloc_failure();
2883 op_updaterefs();
2884 }
2885
2886 void ShenandoahHeap::entry_weak_roots() {
2887 static const char* msg = "Concurrent weak roots";
2888 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_weak_roots);
2889 EventMark em("%s", msg);
2890
2891 ShenandoahWorkerScope scope(workers(),
2892 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2893 "concurrent weak root");
2894
2895 try_inject_alloc_failure();
2896 op_weak_roots();
2897 }
2898
2899 void ShenandoahHeap::entry_class_unloading() {
2900 static const char* msg = "Concurrent class unloading";
2901 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_class_unload);
2902 EventMark em("%s", msg);
2903
2904 ShenandoahWorkerScope scope(workers(),
2905 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2906 "concurrent class unloading");
2907
2908 try_inject_alloc_failure();
2909 op_class_unloading();
2910 }
2911
2912 void ShenandoahHeap::entry_strong_roots() {
2913 static const char* msg = "Concurrent strong roots";
2914 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_strong_roots);
2915 EventMark em("%s", msg);
2916
2917 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_strong_roots);
2918
2919 ShenandoahWorkerScope scope(workers(),
2920 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2921 "concurrent strong root");
2922
2923 try_inject_alloc_failure();
2924 op_strong_roots();
2925 }
2926
2927 void ShenandoahHeap::entry_cleanup_early() {
2928 static const char* msg = "Concurrent cleanup";
2929 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_cleanup_early, true /* log_heap_usage */);
2930 EventMark em("%s", msg);
2931
2932 // This phase does not use workers, no need for setup
2933
2934 try_inject_alloc_failure();
2935 op_cleanup_early();
2936 }
2937
2938 void ShenandoahHeap::entry_cleanup_complete() {
2939 static const char* msg = "Concurrent cleanup";
2940 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_cleanup_complete, true /* log_heap_usage */);
2941 EventMark em("%s", msg);
2942
2943 // This phase does not use workers, no need for setup
2944
2945 try_inject_alloc_failure();
2946 op_cleanup_complete();
2947 }
2948
2949 void ShenandoahHeap::entry_reset() {
2950 static const char* msg = "Concurrent reset";
2951 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_reset);
2952 EventMark em("%s", msg);
2953
2954 ShenandoahWorkerScope scope(workers(),
2955 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2956 "concurrent reset");
2957
2958 try_inject_alloc_failure();
2959 op_reset();
2960 }
2961
2962 void ShenandoahHeap::entry_preclean() {
2963 if (ShenandoahPreclean && process_references()) {
2964 static const char* msg = "Concurrent precleaning";
2965 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_preclean);
2966 EventMark em("%s", msg);
2967
2968 ShenandoahWorkerScope scope(workers(),
2969 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2970 "concurrent preclean",
2971 /* check_workers = */ false);
2972
2973 try_inject_alloc_failure();
2974 op_preclean();
2975 }
2976 }
2977
2978 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2979 static const char *msg = "Concurrent uncommit";
2980 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
2981 EventMark em("%s", msg);
2982
2983 op_uncommit(shrink_before);
2984 }
2985
2986 void ShenandoahHeap::try_inject_alloc_failure() {
2987 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2988 _inject_alloc_failure.set();
2989 os::naked_short_sleep(1);
2990 if (cancelled_gc()) {
2991 log_info(gc)("Allocation failure was successfully injected");
2992 }
2993 }
2994 }
2995
2996 bool ShenandoahHeap::should_inject_alloc_failure() {
2997 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2998 }
2999
3000 void ShenandoahHeap::initialize_serviceability() {
3001 _memory_pool = new ShenandoahMemoryPool(this);
3002 _cycle_memory_manager.add_pool(_memory_pool);
3003 _stw_memory_manager.add_pool(_memory_pool);
3004 }
3005
3006 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
3007 GrowableArray<GCMemoryManager*> memory_managers(2);
3008 memory_managers.append(&_cycle_memory_manager);
3009 memory_managers.append(&_stw_memory_manager);
3010 return memory_managers;
3011 }
3012
3013 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
3014 GrowableArray<MemoryPool*> memory_pools(1);
3015 memory_pools.append(_memory_pool);
3016 return memory_pools;
3017 }
3018
3019 MemoryUsage ShenandoahHeap::memory_usage() {
3020 return _memory_pool->get_memory_usage();
3021 }
3022
3023 ShenandoahRegionIterator::ShenandoahRegionIterator() :
3024 _heap(ShenandoahHeap::heap()),
3025 _index(0) {}
3026
3027 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
3028 _heap(heap),
3029 _index(0) {}
3030
3031 void ShenandoahRegionIterator::reset() {
3032 _index = 0;
3033 }
3034
3035 bool ShenandoahRegionIterator::has_next() const {
3036 return _index < _heap->num_regions();
3037 }
3038
3039 char ShenandoahHeap::gc_state() const {
3040 return _gc_state.raw_value();
3041 }
3042
3043 void ShenandoahHeap::deduplicate_string(oop str) {
3044 assert(java_lang_String::is_instance(str), "invariant");
3045
3046 if (ShenandoahStringDedup::is_enabled()) {
3047 ShenandoahStringDedup::deduplicate(str);
3048 }
3049 }
3050
3051 const char* ShenandoahHeap::init_mark_event_message() const {
3052 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3053
3054 bool proc_refs = process_references();
3055 bool unload_cls = unload_classes();
3056
3057 if (proc_refs && unload_cls) {
3058 return "Pause Init Mark (process weakrefs) (unload classes)";
3059 } else if (proc_refs) {
3060 return "Pause Init Mark (process weakrefs)";
3061 } else if (unload_cls) {
3062 return "Pause Init Mark (unload classes)";
3063 } else {
3064 return "Pause Init Mark";
3065 }
3066 }
3067
3068 const char* ShenandoahHeap::final_mark_event_message() const {
3069 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3070
3071 bool proc_refs = process_references();
3072 bool unload_cls = unload_classes();
3073
3074 if (proc_refs && unload_cls) {
3075 return "Pause Final Mark (process weakrefs) (unload classes)";
3076 } else if (proc_refs) {
3077 return "Pause Final Mark (process weakrefs)";
3078 } else if (unload_cls) {
3079 return "Pause Final Mark (unload classes)";
3080 } else {
3081 return "Pause Final Mark";
3082 }
3083 }
3084
3085 const char* ShenandoahHeap::conc_mark_event_message() const {
3086 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3087
3088 bool proc_refs = process_references();
3089 bool unload_cls = unload_classes();
3090
3091 if (proc_refs && unload_cls) {
3092 return "Concurrent marking (process weakrefs) (unload classes)";
3093 } else if (proc_refs) {
3094 return "Concurrent marking (process weakrefs)";
3095 } else if (unload_cls) {
3096 return "Concurrent marking (unload classes)";
3097 } else {
3098 return "Concurrent marking";
3099 }
3100 }
3101
3102 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
3103 switch (point) {
3104 case _degenerated_unset:
3105 return "Pause Degenerated GC (<UNSET>)";
3106 case _degenerated_outside_cycle:
3107 return "Pause Degenerated GC (Outside of Cycle)";
3108 case _degenerated_mark:
3109 return "Pause Degenerated GC (Mark)";
3110 case _degenerated_evac:
3111 return "Pause Degenerated GC (Evacuation)";
3112 case _degenerated_updaterefs:
3113 return "Pause Degenerated GC (Update Refs)";
3114 default:
3115 ShouldNotReachHere();
3116 return "ERROR";
3117 }
3118 }
3119
3120 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
3121 #ifdef ASSERT
3122 assert(_liveness_cache != NULL, "sanity");
3123 assert(worker_id < _max_workers, "sanity");
3124 for (uint i = 0; i < num_regions(); i++) {
3125 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
3126 }
3127 #endif
3128 return _liveness_cache[worker_id];
3129 }
3130
3131 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
3132 assert(worker_id < _max_workers, "sanity");
3133 assert(_liveness_cache != NULL, "sanity");
3134 ShenandoahLiveData* ld = _liveness_cache[worker_id];
3135 for (uint i = 0; i < num_regions(); i++) {
3136 ShenandoahLiveData live = ld[i];
3137 if (live > 0) {
3138 ShenandoahHeapRegion* r = get_region(i);
3139 r->increase_live_data_gc_words(live);
3140 ld[i] = 0;
3141 }
3142 }
3143 }