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