1 /*
2 * Copyright (c) 2013, 2020, Red Hat, Inc. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.hpp"
27 #include "memory/universe.hpp"
28
29 #include "gc/shared/gcArguments.hpp"
30 #include "gc/shared/gcTimer.hpp"
31 #include "gc/shared/gcTraceTime.inline.hpp"
32 #include "gc/shared/locationPrinter.inline.hpp"
33 #include "gc/shared/memAllocator.hpp"
34 #include "gc/shared/oopStorageSet.hpp"
35 #include "gc/shared/plab.hpp"
36
37 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
38 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
39 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
40 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
41 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
42 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
43 #include "gc/shenandoah/shenandoahControlThread.hpp"
44 #include "gc/shenandoah/shenandoahFreeSet.hpp"
45 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
46 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
47 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
48 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
49 #include "gc/shenandoah/shenandoahIUMode.hpp"
50 #include "gc/shenandoah/shenandoahMarkCompact.hpp"
51 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
52 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
53 #include "gc/shenandoah/shenandoahMetrics.hpp"
54 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
55 #include "gc/shenandoah/shenandoahNormalMode.hpp"
56 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
57 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
58 #include "gc/shenandoah/shenandoahPadding.hpp"
59 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
60 #include "gc/shenandoah/shenandoahPassiveMode.hpp"
61 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
62 #include "gc/shenandoah/shenandoahStringDedup.hpp"
63 #include "gc/shenandoah/shenandoahTaskqueue.hpp"
64 #include "gc/shenandoah/shenandoahUtils.hpp"
65 #include "gc/shenandoah/shenandoahVerifier.hpp"
66 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
67 #include "gc/shenandoah/shenandoahVMOperations.hpp"
68 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
69 #include "gc/shenandoah/shenandoahWorkerPolicy.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 ShenandoahHeap* ShenandoahHeap::_heap = NULL;
86
87 #ifdef ASSERT
88 template <class T>
89 void ShenandoahAssertToSpaceClosure::do_oop_work(T* p) {
90 T o = RawAccess<>::oop_load(p);
91 if (! CompressedOops::is_null(o)) {
92 oop obj = CompressedOops::decode_not_null(o);
93 shenandoah_assert_not_forwarded(p, obj);
94 }
95 }
96
97 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_work(p); }
98 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_work(p); }
99 #endif
100
101 class ShenandoahPretouchHeapTask : public AbstractGangTask {
102 private:
103 ShenandoahRegionIterator _regions;
104 const size_t _page_size;
105 public:
106 ShenandoahPretouchHeapTask(size_t page_size) :
107 AbstractGangTask("Shenandoah Pretouch Heap"),
108 _page_size(page_size) {}
109
110 virtual void work(uint worker_id) {
111 ShenandoahHeapRegion* r = _regions.next();
112 while (r != NULL) {
113 os::pretouch_memory(r->bottom(), r->end(), _page_size);
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 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
140
141 r = _regions.next();
142 }
143 }
144 };
145
146 jint ShenandoahHeap::initialize() {
147 //
148 // Figure out heap sizing
149 //
150
151 size_t init_byte_size = InitialHeapSize;
152 size_t min_byte_size = MinHeapSize;
153 size_t max_byte_size = MaxHeapSize;
154 size_t heap_alignment = HeapAlignment;
155
156 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
157
158 if (ShenandoahAlwaysPreTouch) {
159 // Enabled pre-touch means the entire heap is committed right away.
160 init_byte_size = max_byte_size;
161 }
162
163 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
164 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
165
166 _num_regions = ShenandoahHeapRegion::region_count();
167
168 // Now we know the number of regions, initialize the heuristics.
169 initialize_heuristics();
170
171 size_t num_committed_regions = init_byte_size / reg_size_bytes;
172 num_committed_regions = MIN2(num_committed_regions, _num_regions);
173 assert(num_committed_regions <= _num_regions, "sanity");
174 _initial_size = num_committed_regions * reg_size_bytes;
175
176 size_t num_min_regions = min_byte_size / reg_size_bytes;
177 num_min_regions = MIN2(num_min_regions, _num_regions);
178 assert(num_min_regions <= _num_regions, "sanity");
179 _minimum_size = num_min_regions * reg_size_bytes;
180
181 _committed = _initial_size;
182
183 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
184 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
185 size_t region_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
186
187 //
188 // Reserve and commit memory for heap
189 //
190
191 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
192 initialize_reserved_region(heap_rs);
193 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
194 _heap_region_special = heap_rs.special();
195
196 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
197 "Misaligned heap: " PTR_FORMAT, p2i(base()));
198
199 #if SHENANDOAH_OPTIMIZED_OBJTASK
200 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
201 // Fail if we ever attempt to address more than we can.
202 if ((uintptr_t)heap_rs.end() >= ObjArrayChunkedTask::max_addressable()) {
203 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
204 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
205 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
206 p2i(heap_rs.base()), p2i(heap_rs.end()), ObjArrayChunkedTask::max_addressable());
207 vm_exit_during_initialization("Fatal Error", buf);
208 }
209 #endif
210
211 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
212 if (!_heap_region_special) {
213 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
214 "Cannot commit heap memory");
215 }
216
217 //
218 // Reserve and commit memory for bitmap(s)
219 //
220
221 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
222 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
223
224 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
225
226 guarantee(bitmap_bytes_per_region != 0,
227 "Bitmap bytes per region should not be zero");
228 guarantee(is_power_of_2(bitmap_bytes_per_region),
229 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
230
231 if (bitmap_page_size > bitmap_bytes_per_region) {
232 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
233 _bitmap_bytes_per_slice = bitmap_page_size;
234 } else {
235 _bitmap_regions_per_slice = 1;
236 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
237 }
238
239 guarantee(_bitmap_regions_per_slice >= 1,
240 "Should have at least one region per slice: " SIZE_FORMAT,
241 _bitmap_regions_per_slice);
242
243 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
244 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
245 _bitmap_bytes_per_slice, bitmap_page_size);
246
247 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
248 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
249 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
250 _bitmap_region_special = bitmap.special();
251
252 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
253 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
254 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
255 if (!_bitmap_region_special) {
256 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
257 "Cannot commit bitmap memory");
258 }
259
260 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
261
262 if (ShenandoahVerify) {
263 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
264 if (!verify_bitmap.special()) {
265 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
266 "Cannot commit verification bitmap memory");
267 }
268 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
269 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
270 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
271 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
272 }
273
274 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
275 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
276 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
277 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
278 _aux_bitmap_region_special = aux_bitmap.special();
279 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
280
281 //
282 // Create regions and region sets
283 //
284 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
285 size_t region_storage_size = align_up(region_align * _num_regions, region_page_size);
286 region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity());
287
288 ReservedSpace region_storage(region_storage_size, region_page_size);
289 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
290 if (!region_storage.special()) {
291 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
292 "Cannot commit region memory");
293 }
294
295 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
296 _free_set = new ShenandoahFreeSet(this, _num_regions);
297 _collection_set = new ShenandoahCollectionSet(this, sh_rs.base(), sh_rs.size());
298
299 {
300 ShenandoahHeapLocker locker(lock());
301
302 for (size_t i = 0; i < _num_regions; i++) {
303 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
304 bool is_committed = i < num_committed_regions;
305 void* loc = region_storage.base() + i * region_align;
306
307 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
308 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
309
310 _marking_context->initialize_top_at_mark_start(r);
311 _regions[i] = r;
312 assert(!collection_set()->is_in(i), "New region should not be in collection set");
313 }
314
315 // Initialize to complete
316 _marking_context->mark_complete();
317
318 _free_set->rebuild();
319 }
320
321 if (ShenandoahAlwaysPreTouch) {
322 assert(!AlwaysPreTouch, "Should have been overridden");
323
324 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
325 // before initialize() below zeroes it with initializing thread. For any given region,
326 // we touch the region and the corresponding bitmaps from the same thread.
327 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
328
329 size_t pretouch_heap_page_size = heap_page_size;
330 size_t pretouch_bitmap_page_size = bitmap_page_size;
331
332 #ifdef LINUX
333 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
334 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
335 // them into huge one. Therefore, we need to pretouch with smaller pages.
336 if (UseTransparentHugePages) {
337 pretouch_heap_page_size = (size_t)os::vm_page_size();
338 pretouch_bitmap_page_size = (size_t)os::vm_page_size();
339 }
340 #endif
341
342 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
343 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
344
345 log_info(gc, init)("Pretouch bitmap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
346 _num_regions, pretouch_bitmap_page_size);
347 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, pretouch_bitmap_page_size);
348 _workers->run_task(&bcl);
349
350 log_info(gc, init)("Pretouch heap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
351 _num_regions, pretouch_heap_page_size);
352 ShenandoahPretouchHeapTask hcl(pretouch_heap_page_size);
353 _workers->run_task(&hcl);
354 }
355
356 //
357 // Initialize the rest of GC subsystems
358 //
359
360 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
361 for (uint worker = 0; worker < _max_workers; worker++) {
362 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
363 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
364 }
365
366 // There should probably be Shenandoah-specific options for these,
367 // just as there are G1-specific options.
368 {
369 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
370 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
371 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
372 }
373
374 _monitoring_support = new ShenandoahMonitoringSupport(this);
375 _phase_timings = new ShenandoahPhaseTimings();
376 ShenandoahStringDedup::initialize();
377 ShenandoahCodeRoots::initialize();
378
379 if (ShenandoahPacing) {
380 _pacer = new ShenandoahPacer(this);
381 _pacer->setup_for_idle();
382 } else {
383 _pacer = NULL;
384 }
385
386 _control_thread = new ShenandoahControlThread();
387
388 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max",
389 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size),
390 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size),
391 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity())
392 );
393
394 log_info(gc, init)("Safepointing mechanism: thread-local poll");
395
396 return JNI_OK;
397 }
398
399 void ShenandoahHeap::initialize_heuristics() {
400 if (ShenandoahGCMode != NULL) {
401 if (strcmp(ShenandoahGCMode, "normal") == 0) {
402 _gc_mode = new ShenandoahNormalMode();
403 } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
404 _gc_mode = new ShenandoahIUMode();
405 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
406 _gc_mode = new ShenandoahPassiveMode();
407 } else {
408 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
409 }
410 } else {
411 ShouldNotReachHere();
412 }
413 _gc_mode->initialize_flags();
414 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
415 vm_exit_during_initialization(
416 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
417 _gc_mode->name()));
418 }
419 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
420 vm_exit_during_initialization(
421 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
422 _gc_mode->name()));
423 }
424 log_info(gc, init)("Shenandoah GC mode: %s",
425 _gc_mode->name());
426
427 _heuristics = _gc_mode->initialize_heuristics();
428
429 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
430 vm_exit_during_initialization(
431 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
432 _heuristics->name()));
433 }
434 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
435 vm_exit_during_initialization(
436 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
437 _heuristics->name()));
438 }
439 log_info(gc, init)("Shenandoah heuristics: %s",
440 _heuristics->name());
441 }
442
443 #ifdef _MSC_VER
444 #pragma warning( push )
445 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
446 #endif
447
448 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
449 CollectedHeap(),
450 _initial_size(0),
451 _used(0),
452 _committed(0),
453 _bytes_allocated_since_gc_start(0),
454 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
455 _workers(NULL),
456 _safepoint_workers(NULL),
457 _heap_region_special(false),
458 _num_regions(0),
459 _regions(NULL),
460 _update_refs_iterator(this),
461 _control_thread(NULL),
462 _shenandoah_policy(policy),
463 _heuristics(NULL),
464 _free_set(NULL),
465 _scm(new ShenandoahConcurrentMark()),
466 _full_gc(new ShenandoahMarkCompact()),
467 _pacer(NULL),
468 _verifier(NULL),
469 _phase_timings(NULL),
470 _monitoring_support(NULL),
471 _memory_pool(NULL),
472 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
473 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
474 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
475 _soft_ref_policy(),
476 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
477 _ref_processor(NULL),
478 _marking_context(NULL),
479 _bitmap_size(0),
480 _bitmap_regions_per_slice(0),
481 _bitmap_bytes_per_slice(0),
482 _bitmap_region_special(false),
483 _aux_bitmap_region_special(false),
484 _liveness_cache(NULL),
485 _collection_set(NULL)
486 {
487 _heap = this;
488
489 log_info(gc, init)("GC threads: " UINT32_FORMAT " parallel, " UINT32_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
490
491 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
492
493 _max_workers = MAX2(_max_workers, 1U);
494 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
495 /* are_GC_task_threads */ true,
496 /* are_ConcurrentGC_threads */ true);
497 if (_workers == NULL) {
498 vm_exit_during_initialization("Failed necessary allocation.");
499 } else {
500 _workers->initialize_workers();
501 }
502
503 if (ParallelGCThreads > 1) {
504 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
505 ParallelGCThreads,
506 /* are_GC_task_threads */ false,
507 /* are_ConcurrentGC_threads */ false);
508 _safepoint_workers->initialize_workers();
509 }
510 }
511
512 #ifdef _MSC_VER
513 #pragma warning( pop )
514 #endif
515
516 class ShenandoahResetBitmapTask : public AbstractGangTask {
517 private:
518 ShenandoahRegionIterator _regions;
519
520 public:
521 ShenandoahResetBitmapTask() :
522 AbstractGangTask("Parallel Reset Bitmap Task") {}
523
524 void work(uint worker_id) {
525 ShenandoahHeapRegion* region = _regions.next();
526 ShenandoahHeap* heap = ShenandoahHeap::heap();
527 ShenandoahMarkingContext* const ctx = heap->marking_context();
528 while (region != NULL) {
529 if (heap->is_bitmap_slice_committed(region)) {
530 ctx->clear_bitmap(region);
531 }
532 region = _regions.next();
533 }
534 }
535 };
536
537 void ShenandoahHeap::reset_mark_bitmap() {
538 assert_gc_workers(_workers->active_workers());
539 mark_incomplete_marking_context();
540
541 ShenandoahResetBitmapTask task;
542 _workers->run_task(&task);
543 }
544
545 void ShenandoahHeap::print_on(outputStream* st) const {
546 st->print_cr("Shenandoah Heap");
547 st->print_cr(" " SIZE_FORMAT "%s total, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
548 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
549 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
550 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
551 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
552 num_regions(),
553 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
554 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
555
556 st->print("Status: ");
557 if (has_forwarded_objects()) st->print("has forwarded objects, ");
558 if (is_concurrent_mark_in_progress()) st->print("marking, ");
559 if (is_evacuation_in_progress()) st->print("evacuating, ");
560 if (is_update_refs_in_progress()) st->print("updating refs, ");
561 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
562 if (is_full_gc_in_progress()) st->print("full gc, ");
563 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
564 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
565 if (is_concurrent_strong_root_in_progress() &&
566 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
567
568 if (cancelled_gc()) {
569 st->print("cancelled");
570 } else {
571 st->print("not cancelled");
572 }
573 st->cr();
574
575 st->print_cr("Reserved region:");
576 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
577 p2i(reserved_region().start()),
578 p2i(reserved_region().end()));
579
580 ShenandoahCollectionSet* cset = collection_set();
581 st->print_cr("Collection set:");
582 if (cset != NULL) {
583 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
584 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
585 } else {
586 st->print_cr(" (NULL)");
587 }
588
589 st->cr();
590 MetaspaceUtils::print_on(st);
591
592 if (Verbose) {
593 print_heap_regions_on(st);
594 }
595 }
596
597 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
598 public:
599 void do_thread(Thread* thread) {
600 assert(thread != NULL, "Sanity");
601 assert(thread->is_Worker_thread(), "Only worker thread expected");
602 ShenandoahThreadLocalData::initialize_gclab(thread);
603 }
604 };
605
606 void ShenandoahHeap::post_initialize() {
607 CollectedHeap::post_initialize();
608 MutexLocker ml(Threads_lock);
609
610 ShenandoahInitWorkerGCLABClosure init_gclabs;
611 _workers->threads_do(&init_gclabs);
612
613 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
614 // Now, we will let WorkGang to initialize gclab when new worker is created.
615 _workers->set_initialize_gclab();
616
617 _scm->initialize(_max_workers);
618 _full_gc->initialize(_gc_timer);
619
620 ref_processing_init();
621
622 _heuristics->initialize();
623
624 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
625 }
626
627 size_t ShenandoahHeap::used() const {
628 return Atomic::load_acquire(&_used);
629 }
630
631 size_t ShenandoahHeap::committed() const {
632 OrderAccess::acquire();
633 return _committed;
634 }
635
636 void ShenandoahHeap::increase_committed(size_t bytes) {
637 shenandoah_assert_heaplocked_or_safepoint();
638 _committed += bytes;
639 }
640
641 void ShenandoahHeap::decrease_committed(size_t bytes) {
642 shenandoah_assert_heaplocked_or_safepoint();
643 _committed -= bytes;
644 }
645
646 void ShenandoahHeap::increase_used(size_t bytes) {
647 Atomic::add(&_used, bytes);
648 }
649
650 void ShenandoahHeap::set_used(size_t bytes) {
651 Atomic::release_store_fence(&_used, bytes);
652 }
653
654 void ShenandoahHeap::decrease_used(size_t bytes) {
655 assert(used() >= bytes, "never decrease heap size by more than we've left");
656 Atomic::sub(&_used, bytes);
657 }
658
659 void ShenandoahHeap::increase_allocated(size_t bytes) {
660 Atomic::add(&_bytes_allocated_since_gc_start, bytes);
661 }
662
663 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
664 size_t bytes = words * HeapWordSize;
665 if (!waste) {
666 increase_used(bytes);
667 }
668 increase_allocated(bytes);
669 if (ShenandoahPacing) {
670 control_thread()->pacing_notify_alloc(words);
671 if (waste) {
672 pacer()->claim_for_alloc(words, true);
673 }
674 }
675 }
676
677 size_t ShenandoahHeap::capacity() const {
678 return committed();
679 }
680
681 size_t ShenandoahHeap::max_capacity() const {
682 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
683 }
684
685 size_t ShenandoahHeap::min_capacity() const {
686 return _minimum_size;
687 }
688
689 size_t ShenandoahHeap::initial_capacity() const {
690 return _initial_size;
691 }
692
693 bool ShenandoahHeap::is_in(const void* p) const {
694 HeapWord* heap_base = (HeapWord*) base();
695 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
696 return p >= heap_base && p < last_region_end;
697 }
698
699 void ShenandoahHeap::op_uncommit(double shrink_before) {
700 assert (ShenandoahUncommit, "should be enabled");
701
702 // Application allocates from the beginning of the heap, and GC allocates at
703 // the end of it. It is more efficient to uncommit from the end, so that applications
704 // could enjoy the near committed regions. GC allocations are much less frequent,
705 // and therefore can accept the committing costs.
706
707 size_t count = 0;
708 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
709 ShenandoahHeapRegion* r = get_region(i - 1);
710 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
711 ShenandoahHeapLocker locker(lock());
712 if (r->is_empty_committed()) {
713 // Do not uncommit below minimal capacity
714 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
715 break;
716 }
717
718 r->make_uncommitted();
719 count++;
720 }
721 }
722 SpinPause(); // allow allocators to take the lock
723 }
724
725 if (count > 0) {
726 control_thread()->notify_heap_changed();
727 }
728 }
729
730 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
731 // New object should fit the GCLAB size
732 size_t min_size = MAX2(size, PLAB::min_size());
733
734 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
735 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
736 new_size = MIN2(new_size, PLAB::max_size());
737 new_size = MAX2(new_size, PLAB::min_size());
738
739 // Record new heuristic value even if we take any shortcut. This captures
740 // the case when moderately-sized objects always take a shortcut. At some point,
741 // heuristics should catch up with them.
742 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
743
744 if (new_size < size) {
745 // New size still does not fit the object. Fall back to shared allocation.
746 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
747 return NULL;
748 }
749
750 // Retire current GCLAB, and allocate a new one.
751 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
752 gclab->retire();
753
754 size_t actual_size = 0;
755 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
756 if (gclab_buf == NULL) {
757 return NULL;
758 }
759
760 assert (size <= actual_size, "allocation should fit");
761
762 if (ZeroTLAB) {
763 // ..and clear it.
764 Copy::zero_to_words(gclab_buf, actual_size);
765 } else {
766 // ...and zap just allocated object.
767 #ifdef ASSERT
768 // Skip mangling the space corresponding to the object header to
769 // ensure that the returned space is not considered parsable by
770 // any concurrent GC thread.
771 size_t hdr_size = oopDesc::header_size();
772 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
773 #endif // ASSERT
774 }
775 gclab->set_buf(gclab_buf, actual_size);
776 return gclab->allocate(size);
777 }
778
779 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
780 size_t requested_size,
781 size_t* actual_size) {
782 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
783 HeapWord* res = allocate_memory(req);
784 if (res != NULL) {
785 *actual_size = req.actual_size();
786 } else {
787 *actual_size = 0;
788 }
789 return res;
790 }
791
792 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
793 size_t word_size,
794 size_t* actual_size) {
795 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
796 HeapWord* res = allocate_memory(req);
797 if (res != NULL) {
798 *actual_size = req.actual_size();
799 } else {
800 *actual_size = 0;
801 }
802 return res;
803 }
804
805 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
806 intptr_t pacer_epoch = 0;
807 bool in_new_region = false;
808 HeapWord* result = NULL;
809
810 if (req.is_mutator_alloc()) {
811 if (ShenandoahPacing) {
812 pacer()->pace_for_alloc(req.size());
813 pacer_epoch = pacer()->epoch();
814 }
815
816 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
817 result = allocate_memory_under_lock(req, in_new_region);
818 }
819
820 // Allocation failed, block until control thread reacted, then retry allocation.
821 //
822 // It might happen that one of the threads requesting allocation would unblock
823 // way later after GC happened, only to fail the second allocation, because
824 // other threads have already depleted the free storage. In this case, a better
825 // strategy is to try again, as long as GC makes progress.
826 //
827 // Then, we need to make sure the allocation was retried after at least one
828 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
829
830 size_t tries = 0;
831
832 while (result == NULL && _progress_last_gc.is_set()) {
833 tries++;
834 control_thread()->handle_alloc_failure(req);
835 result = allocate_memory_under_lock(req, in_new_region);
836 }
837
838 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
839 tries++;
840 control_thread()->handle_alloc_failure(req);
841 result = allocate_memory_under_lock(req, in_new_region);
842 }
843
844 } else {
845 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
846 result = allocate_memory_under_lock(req, in_new_region);
847 // Do not call handle_alloc_failure() here, because we cannot block.
848 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
849 }
850
851 if (in_new_region) {
852 control_thread()->notify_heap_changed();
853 }
854
855 if (result != NULL) {
856 size_t requested = req.size();
857 size_t actual = req.actual_size();
858
859 assert (req.is_lab_alloc() || (requested == actual),
860 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
861 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
862
863 if (req.is_mutator_alloc()) {
864 notify_mutator_alloc_words(actual, false);
865
866 // If we requested more than we were granted, give the rest back to pacer.
867 // This only matters if we are in the same pacing epoch: do not try to unpace
868 // over the budget for the other phase.
869 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
870 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
871 }
872 } else {
873 increase_used(actual*HeapWordSize);
874 }
875 }
876
877 return result;
878 }
879
880 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
881 ShenandoahHeapLocker locker(lock());
882 return _free_set->allocate(req, in_new_region);
883 }
884
885 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
886 bool* gc_overhead_limit_was_exceeded) {
887 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
888 return allocate_memory(req);
889 }
890
891 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
892 size_t size,
893 Metaspace::MetadataType mdtype) {
894 MetaWord* result;
895
896 // Inform metaspace OOM to GC heuristics if class unloading is possible.
897 if (heuristics()->can_unload_classes()) {
898 ShenandoahHeuristics* h = heuristics();
899 h->record_metaspace_oom();
900 }
901
902 // Expand and retry allocation
903 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
904 if (result != NULL) {
905 return result;
906 }
907
908 // Start full GC
909 collect(GCCause::_metadata_GC_clear_soft_refs);
910
911 // Retry allocation
912 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
913 if (result != NULL) {
914 return result;
915 }
916
917 // Expand and retry allocation
918 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
919 if (result != NULL) {
920 return result;
921 }
922
923 // Out of memory
924 return NULL;
925 }
926
927 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
928 private:
929 ShenandoahHeap* const _heap;
930 Thread* const _thread;
931 public:
932 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
933 _heap(heap), _thread(Thread::current()) {}
934
935 void do_object(oop p) {
936 shenandoah_assert_marked(NULL, p);
937 if (!p->is_forwarded()) {
938 _heap->evacuate_object(p, _thread);
939 }
940 }
941 };
942
943 class ShenandoahEvacuationTask : public AbstractGangTask {
944 private:
945 ShenandoahHeap* const _sh;
946 ShenandoahCollectionSet* const _cs;
947 bool _concurrent;
948 public:
949 ShenandoahEvacuationTask(ShenandoahHeap* sh,
950 ShenandoahCollectionSet* cs,
951 bool concurrent) :
952 AbstractGangTask("Parallel Evacuation Task"),
953 _sh(sh),
954 _cs(cs),
955 _concurrent(concurrent)
956 {}
957
958 void work(uint worker_id) {
959 if (_concurrent) {
960 ShenandoahConcurrentWorkerSession worker_session(worker_id);
961 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
962 ShenandoahEvacOOMScope oom_evac_scope;
963 do_work();
964 } else {
965 ShenandoahParallelWorkerSession worker_session(worker_id);
966 ShenandoahEvacOOMScope oom_evac_scope;
967 do_work();
968 }
969 }
970
971 private:
972 void do_work() {
973 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
974 ShenandoahHeapRegion* r;
975 while ((r =_cs->claim_next()) != NULL) {
976 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
977 _sh->marked_object_iterate(r, &cl);
978
979 if (ShenandoahPacing) {
980 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
981 }
982
983 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
984 break;
985 }
986 }
987 }
988 };
989
990 void ShenandoahHeap::trash_cset_regions() {
991 ShenandoahHeapLocker locker(lock());
992
993 ShenandoahCollectionSet* set = collection_set();
994 ShenandoahHeapRegion* r;
995 set->clear_current_index();
996 while ((r = set->next()) != NULL) {
997 r->make_trash();
998 }
999 collection_set()->clear();
1000 }
1001
1002 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1003 st->print_cr("Heap Regions:");
1004 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
1005 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
1006 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark");
1007 st->print_cr("SN=alloc sequence number");
1008
1009 for (size_t i = 0; i < num_regions(); i++) {
1010 get_region(i)->print_on(st);
1011 }
1012 }
1013
1014 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1015 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1016
1017 oop humongous_obj = oop(start->bottom());
1018 size_t size = humongous_obj->size();
1019 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1020 size_t index = start->index() + required_regions - 1;
1021
1022 assert(!start->has_live(), "liveness must be zero");
1023
1024 for(size_t i = 0; i < required_regions; i++) {
1025 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1026 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1027 ShenandoahHeapRegion* region = get_region(index --);
1028
1029 assert(region->is_humongous(), "expect correct humongous start or continuation");
1030 assert(!region->is_cset(), "Humongous region should not be in collection set");
1031
1032 region->make_trash_immediate();
1033 }
1034 }
1035
1036 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1037 public:
1038 void do_thread(Thread* thread) {
1039 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1040 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1041 gclab->retire();
1042 }
1043 };
1044
1045 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
1046 if (UseTLAB) {
1047 CollectedHeap::ensure_parsability(retire_tlabs);
1048 }
1049 ShenandoahRetireGCLABClosure cl;
1050 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1051 cl.do_thread(t);
1052 }
1053 workers()->threads_do(&cl);
1054 }
1055
1056 void ShenandoahHeap::resize_tlabs() {
1057 CollectedHeap::resize_all_tlabs();
1058 }
1059
1060 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1061 private:
1062 ShenandoahRootEvacuator* _rp;
1063
1064 public:
1065 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1066 AbstractGangTask("Shenandoah evacuate and update roots"),
1067 _rp(rp) {}
1068
1069 void work(uint worker_id) {
1070 ShenandoahParallelWorkerSession worker_session(worker_id);
1071 ShenandoahEvacOOMScope oom_evac_scope;
1072 ShenandoahEvacuateUpdateRootsClosure<> cl;
1073 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1074 _rp->roots_do(worker_id, &cl);
1075 }
1076 };
1077
1078 void ShenandoahHeap::evacuate_and_update_roots() {
1079 #if COMPILER2_OR_JVMCI
1080 DerivedPointerTable::clear();
1081 #endif
1082 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1083 {
1084 // Include concurrent roots if current cycle can not process those roots concurrently
1085 ShenandoahRootEvacuator rp(workers()->active_workers(),
1086 ShenandoahPhaseTimings::init_evac,
1087 !ShenandoahConcurrentRoots::should_do_concurrent_roots(),
1088 !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
1089 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1090 workers()->run_task(&roots_task);
1091 }
1092
1093 #if COMPILER2_OR_JVMCI
1094 DerivedPointerTable::update_pointers();
1095 #endif
1096 }
1097
1098 // Returns size in bytes
1099 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1100 if (ShenandoahElasticTLAB) {
1101 // With Elastic TLABs, return the max allowed size, and let the allocation path
1102 // figure out the safe size for current allocation.
1103 return ShenandoahHeapRegion::max_tlab_size_bytes();
1104 } else {
1105 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1106 }
1107 }
1108
1109 size_t ShenandoahHeap::max_tlab_size() const {
1110 // Returns size in words
1111 return ShenandoahHeapRegion::max_tlab_size_words();
1112 }
1113
1114 class ShenandoahRetireAndResetGCLABClosure : public ThreadClosure {
1115 public:
1116 void do_thread(Thread* thread) {
1117 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1118 gclab->retire();
1119 if (ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1120 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1121 }
1122 }
1123 };
1124
1125 void ShenandoahHeap::retire_and_reset_gclabs() {
1126 ShenandoahRetireAndResetGCLABClosure cl;
1127 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1128 cl.do_thread(t);
1129 }
1130 workers()->threads_do(&cl);
1131 }
1132
1133 void ShenandoahHeap::collect(GCCause::Cause cause) {
1134 control_thread()->request_gc(cause);
1135 }
1136
1137 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1138 //assert(false, "Shouldn't need to do full collections");
1139 }
1140
1141 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1142 ShenandoahHeapRegion* r = heap_region_containing(addr);
1143 if (r != NULL) {
1144 return r->block_start(addr);
1145 }
1146 return NULL;
1147 }
1148
1149 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1150 ShenandoahHeapRegion* r = heap_region_containing(addr);
1151 return r->block_is_obj(addr);
1152 }
1153
1154 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1155 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1156 }
1157
1158 jlong ShenandoahHeap::millis_since_last_gc() {
1159 double v = heuristics()->time_since_last_gc() * 1000;
1160 assert(0 <= v && v <= max_jlong, "value should fit: %f", v);
1161 return (jlong)v;
1162 }
1163
1164 void ShenandoahHeap::prepare_for_verify() {
1165 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1166 make_parsable(false);
1167 }
1168 }
1169
1170 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1171 workers()->print_worker_threads_on(st);
1172 if (ShenandoahStringDedup::is_enabled()) {
1173 ShenandoahStringDedup::print_worker_threads_on(st);
1174 }
1175 }
1176
1177 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1178 workers()->threads_do(tcl);
1179 if (_safepoint_workers != NULL) {
1180 _safepoint_workers->threads_do(tcl);
1181 }
1182 if (ShenandoahStringDedup::is_enabled()) {
1183 ShenandoahStringDedup::threads_do(tcl);
1184 }
1185 }
1186
1187 void ShenandoahHeap::print_tracing_info() const {
1188 LogTarget(Info, gc, stats) lt;
1189 if (lt.is_enabled()) {
1190 ResourceMark rm;
1191 LogStream ls(lt);
1192
1193 phase_timings()->print_global_on(&ls);
1194
1195 ls.cr();
1196 ls.cr();
1197
1198 shenandoah_policy()->print_gc_stats(&ls);
1199
1200 ls.cr();
1201 ls.cr();
1202
1203 if (ShenandoahPacing) {
1204 pacer()->print_on(&ls);
1205 }
1206
1207 ls.cr();
1208 ls.cr();
1209 }
1210 }
1211
1212 void ShenandoahHeap::verify(VerifyOption vo) {
1213 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1214 if (ShenandoahVerify) {
1215 verifier()->verify_generic(vo);
1216 } else {
1217 // TODO: Consider allocating verification bitmaps on demand,
1218 // and turn this on unconditionally.
1219 }
1220 }
1221 }
1222 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1223 return _free_set->capacity();
1224 }
1225
1226 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1227 private:
1228 MarkBitMap* _bitmap;
1229 Stack<oop,mtGC>* _oop_stack;
1230 ShenandoahHeap* const _heap;
1231 ShenandoahMarkingContext* const _marking_context;
1232
1233 template <class T>
1234 void do_oop_work(T* p) {
1235 T o = RawAccess<>::oop_load(p);
1236 if (!CompressedOops::is_null(o)) {
1237 oop obj = CompressedOops::decode_not_null(o);
1238 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1239 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1240 return;
1241 }
1242 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1243
1244 assert(oopDesc::is_oop(obj), "must be a valid oop");
1245 if (!_bitmap->is_marked(obj)) {
1246 _bitmap->mark(obj);
1247 _oop_stack->push(obj);
1248 }
1249 }
1250 }
1251 public:
1252 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1253 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1254 _marking_context(_heap->marking_context()) {}
1255 void do_oop(oop* p) { do_oop_work(p); }
1256 void do_oop(narrowOop* p) { do_oop_work(p); }
1257 };
1258
1259 /*
1260 * This is public API, used in preparation of object_iterate().
1261 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1262 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1263 * control, we call SH::make_tlabs_parsable().
1264 */
1265 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1266 // No-op.
1267 }
1268
1269 /*
1270 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1271 *
1272 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1273 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1274 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1275 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1276 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1277 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1278 * wiped the bitmap in preparation for next marking).
1279 *
1280 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1281 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1282 * is allowed to report dead objects, but is not required to do so.
1283 */
1284 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1285 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1286 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1287 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1288 return;
1289 }
1290
1291 // Reset bitmap
1292 _aux_bit_map.clear();
1293
1294 Stack<oop,mtGC> oop_stack;
1295
1296 // First, we process GC roots according to current GC cycle. This populates the work stack with initial objects.
1297 ShenandoahHeapIterationRootScanner rp;
1298 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1299
1300 rp.roots_do(&oops);
1301
1302 // Work through the oop stack to traverse heap.
1303 while (! oop_stack.is_empty()) {
1304 oop obj = oop_stack.pop();
1305 assert(oopDesc::is_oop(obj), "must be a valid oop");
1306 cl->do_object(obj);
1307 obj->oop_iterate(&oops);
1308 }
1309
1310 assert(oop_stack.is_empty(), "should be empty");
1311
1312 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1313 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1314 }
1315 }
1316
1317 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1318 void ShenandoahHeap::keep_alive(oop obj) {
1319 if (is_concurrent_mark_in_progress()) {
1320 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1321 }
1322 }
1323
1324 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1325 for (size_t i = 0; i < num_regions(); i++) {
1326 ShenandoahHeapRegion* current = get_region(i);
1327 blk->heap_region_do(current);
1328 }
1329 }
1330
1331 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1332 private:
1333 ShenandoahHeap* const _heap;
1334 ShenandoahHeapRegionClosure* const _blk;
1335
1336 shenandoah_padding(0);
1337 volatile size_t _index;
1338 shenandoah_padding(1);
1339
1340 public:
1341 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1342 AbstractGangTask("Parallel Region Task"),
1343 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1344
1345 void work(uint worker_id) {
1346 size_t stride = ShenandoahParallelRegionStride;
1347
1348 size_t max = _heap->num_regions();
1349 while (_index < max) {
1350 size_t cur = Atomic::fetch_and_add(&_index, stride);
1351 size_t start = cur;
1352 size_t end = MIN2(cur + stride, max);
1353 if (start >= max) break;
1354
1355 for (size_t i = cur; i < end; i++) {
1356 ShenandoahHeapRegion* current = _heap->get_region(i);
1357 _blk->heap_region_do(current);
1358 }
1359 }
1360 }
1361 };
1362
1363 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1364 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1365 if (num_regions() > ShenandoahParallelRegionStride) {
1366 ShenandoahParallelHeapRegionTask task(blk);
1367 workers()->run_task(&task);
1368 } else {
1369 heap_region_iterate(blk);
1370 }
1371 }
1372
1373 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1374 private:
1375 ShenandoahMarkingContext* const _ctx;
1376 public:
1377 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1378
1379 void heap_region_do(ShenandoahHeapRegion* r) {
1380 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1381 if (r->is_active()) {
1382 // Check if region needs updating its TAMS. We have updated it already during concurrent
1383 // reset, so it is very likely we don't need to do another write here.
1384 if (_ctx->top_at_mark_start(r) != r->top()) {
1385 _ctx->capture_top_at_mark_start(r);
1386 }
1387 } else {
1388 assert(_ctx->top_at_mark_start(r) == r->top(),
1389 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1390 }
1391 }
1392
1393 bool is_thread_safe() { return true; }
1394 };
1395
1396 void ShenandoahHeap::op_init_mark() {
1397 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1398 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1399
1400 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1401 assert(!marking_context()->is_complete(), "should not be complete");
1402 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1403
1404 if (ShenandoahVerify) {
1405 verifier()->verify_before_concmark();
1406 }
1407
1408 if (VerifyBeforeGC) {
1409 Universe::verify();
1410 }
1411
1412 set_concurrent_mark_in_progress(true);
1413 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1414 {
1415 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::make_parsable);
1416 make_parsable(true);
1417 }
1418
1419 {
1420 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::init_update_region_states);
1421 ShenandoahInitMarkUpdateRegionStateClosure cl;
1422 parallel_heap_region_iterate(&cl);
1423 }
1424
1425 // Make above changes visible to worker threads
1426 OrderAccess::fence();
1427
1428 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1429
1430 if (UseTLAB) {
1431 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1432 resize_tlabs();
1433 }
1434
1435 if (ShenandoahPacing) {
1436 pacer()->setup_for_mark();
1437 }
1438
1439 // Arm nmethods for concurrent marking. When a nmethod is about to be executed,
1440 // we need to make sure that all its metadata are marked. alternative is to remark
1441 // thread roots at final mark pause, but it can be potential latency killer.
1442 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1443 ShenandoahCodeRoots::arm_nmethods();
1444 }
1445 }
1446
1447 void ShenandoahHeap::op_mark() {
1448 concurrent_mark()->mark_from_roots();
1449 }
1450
1451 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1452 private:
1453 ShenandoahMarkingContext* const _ctx;
1454 ShenandoahHeapLock* const _lock;
1455
1456 public:
1457 ShenandoahFinalMarkUpdateRegionStateClosure() :
1458 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1459
1460 void heap_region_do(ShenandoahHeapRegion* r) {
1461 if (r->is_active()) {
1462 // All allocations past TAMS are implicitly live, adjust the region data.
1463 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1464 HeapWord *tams = _ctx->top_at_mark_start(r);
1465 HeapWord *top = r->top();
1466 if (top > tams) {
1467 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1468 }
1469
1470 // We are about to select the collection set, make sure it knows about
1471 // current pinning status. Also, this allows trashing more regions that
1472 // now have their pinning status dropped.
1473 if (r->is_pinned()) {
1474 if (r->pin_count() == 0) {
1475 ShenandoahHeapLocker locker(_lock);
1476 r->make_unpinned();
1477 }
1478 } else {
1479 if (r->pin_count() > 0) {
1480 ShenandoahHeapLocker locker(_lock);
1481 r->make_pinned();
1482 }
1483 }
1484
1485 // Remember limit for updating refs. It's guaranteed that we get no
1486 // from-space-refs written from here on.
1487 r->set_update_watermark(r->top());
1488 } else {
1489 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1490 assert(_ctx->top_at_mark_start(r) == r->top(),
1491 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1492 }
1493 }
1494
1495 bool is_thread_safe() { return true; }
1496 };
1497
1498 void ShenandoahHeap::op_final_mark() {
1499 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1500 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1501
1502 // It is critical that we
1503 // evacuate roots right after finishing marking, so that we don't
1504 // get unmarked objects in the roots.
1505
1506 if (!cancelled_gc()) {
1507 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1508
1509 // Marking is completed, deactivate SATB barrier
1510 set_concurrent_mark_in_progress(false);
1511 mark_complete_marking_context();
1512
1513 parallel_cleaning(false /* full gc*/);
1514
1515 if (ShenandoahVerify) {
1516 verifier()->verify_roots_no_forwarded();
1517 }
1518
1519 {
1520 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::final_update_region_states);
1521 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1522 parallel_heap_region_iterate(&cl);
1523
1524 assert_pinned_region_status();
1525 }
1526
1527 // Retire the TLABs, which will force threads to reacquire their TLABs after the pause.
1528 // This is needed for two reasons. Strong one: new allocations would be with new freeset,
1529 // which would be outside the collection set, so no cset writes would happen there.
1530 // Weaker one: new allocations would happen past update watermark, and so less work would
1531 // be needed for reference updates (would update the large filler instead).
1532 {
1533 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::retire_tlabs);
1534 make_parsable(true);
1535 }
1536
1537 {
1538 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::choose_cset);
1539 ShenandoahHeapLocker locker(lock());
1540 _collection_set->clear();
1541 heuristics()->choose_collection_set(_collection_set);
1542 }
1543
1544 {
1545 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::final_rebuild_freeset);
1546 ShenandoahHeapLocker locker(lock());
1547 _free_set->rebuild();
1548 }
1549
1550 if (!is_degenerated_gc_in_progress()) {
1551 prepare_concurrent_roots();
1552 prepare_concurrent_unloading();
1553 }
1554
1555 // If collection set has candidates, start evacuation.
1556 // Otherwise, bypass the rest of the cycle.
1557 if (!collection_set()->is_empty()) {
1558 ShenandoahGCSubPhase init_evac(ShenandoahPhaseTimings::init_evac);
1559
1560 if (ShenandoahVerify) {
1561 verifier()->verify_before_evacuation();
1562 }
1563
1564 set_evacuation_in_progress(true);
1565 // From here on, we need to update references.
1566 set_has_forwarded_objects(true);
1567
1568 if (!is_degenerated_gc_in_progress()) {
1569 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1570 ShenandoahCodeRoots::arm_nmethods();
1571 }
1572 evacuate_and_update_roots();
1573 }
1574
1575 if (ShenandoahPacing) {
1576 pacer()->setup_for_evac();
1577 }
1578
1579 if (ShenandoahVerify) {
1580 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::None;
1581 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1582 types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots);
1583 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots);
1584 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::StringDedupRoots);
1585 }
1586
1587 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1588 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CodeRoots);
1589 }
1590 verifier()->verify_roots_no_forwarded_except(types);
1591 verifier()->verify_during_evacuation();
1592 }
1593 } else {
1594 if (ShenandoahVerify) {
1595 verifier()->verify_after_concmark();
1596 }
1597
1598 if (VerifyAfterGC) {
1599 Universe::verify();
1600 }
1601 }
1602
1603 } else {
1604 // If this cycle was updating references, we need to keep the has_forwarded_objects
1605 // flag on, for subsequent phases to deal with it.
1606 concurrent_mark()->cancel();
1607 set_concurrent_mark_in_progress(false);
1608
1609 if (process_references()) {
1610 // Abandon reference processing right away: pre-cleaning must have failed.
1611 ReferenceProcessor *rp = ref_processor();
1612 rp->disable_discovery();
1613 rp->abandon_partial_discovery();
1614 rp->verify_no_references_recorded();
1615 }
1616 }
1617 }
1618
1619 void ShenandoahHeap::op_conc_evac() {
1620 ShenandoahEvacuationTask task(this, _collection_set, true);
1621 workers()->run_task(&task);
1622 }
1623
1624 void ShenandoahHeap::op_stw_evac() {
1625 ShenandoahEvacuationTask task(this, _collection_set, false);
1626 workers()->run_task(&task);
1627 }
1628
1629 void ShenandoahHeap::op_updaterefs() {
1630 update_heap_references(true);
1631 }
1632
1633 void ShenandoahHeap::op_cleanup_early() {
1634 free_set()->recycle_trash();
1635 }
1636
1637 void ShenandoahHeap::op_cleanup_complete() {
1638 free_set()->recycle_trash();
1639 }
1640
1641 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask {
1642 private:
1643 ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
1644 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots;
1645 ShenandoahConcurrentStringDedupRoots _dedup_roots;
1646
1647 public:
1648 ShenandoahConcurrentRootsEvacUpdateTask() :
1649 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Strong Roots Task") {
1650 }
1651
1652 void work(uint worker_id) {
1653 ShenandoahEvacOOMScope oom;
1654 {
1655 // vm_roots and weak_roots are OopStorage backed roots, concurrent iteration
1656 // may race against OopStorage::release() calls.
1657 ShenandoahEvacUpdateOopStorageRootsClosure cl;
1658 _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl, worker_id);
1659 }
1660
1661 {
1662 ShenandoahEvacuateUpdateRootsClosure<> cl;
1663 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1664 _cld_roots.cld_do(&clds, worker_id);
1665 }
1666
1667 {
1668 ShenandoahForwardedIsAliveClosure is_alive;
1669 ShenandoahEvacuateUpdateRootsClosure<MO_RELEASE> keep_alive;
1670 _dedup_roots.oops_do(&is_alive, &keep_alive, worker_id);
1671 }
1672 }
1673 };
1674
1675 class ShenandoahEvacUpdateCleanupOopStorageRootsClosure : public BasicOopIterateClosure {
1676 private:
1677 ShenandoahHeap* const _heap;
1678 ShenandoahMarkingContext* const _mark_context;
1679 bool _evac_in_progress;
1680 Thread* const _thread;
1681 size_t _dead_counter;
1682
1683 public:
1684 ShenandoahEvacUpdateCleanupOopStorageRootsClosure();
1685 void do_oop(oop* p);
1686 void do_oop(narrowOop* p);
1687
1688 size_t dead_counter() const;
1689 void reset_dead_counter();
1690 };
1691
1692 ShenandoahEvacUpdateCleanupOopStorageRootsClosure::ShenandoahEvacUpdateCleanupOopStorageRootsClosure() :
1693 _heap(ShenandoahHeap::heap()),
1694 _mark_context(ShenandoahHeap::heap()->marking_context()),
1695 _evac_in_progress(ShenandoahHeap::heap()->is_evacuation_in_progress()),
1696 _thread(Thread::current()),
1697 _dead_counter(0) {
1698 }
1699
1700 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(oop* p) {
1701 const oop obj = RawAccess<>::oop_load(p);
1702 if (!CompressedOops::is_null(obj)) {
1703 if (!_mark_context->is_marked(obj)) {
1704 shenandoah_assert_correct(p, obj);
1705 oop old = Atomic::cmpxchg(p, obj, oop(NULL));
1706 if (obj == old) {
1707 _dead_counter ++;
1708 }
1709 } else if (_evac_in_progress && _heap->in_collection_set(obj)) {
1710 oop resolved = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1711 if (resolved == obj) {
1712 resolved = _heap->evacuate_object(obj, _thread);
1713 }
1714 Atomic::cmpxchg(p, obj, resolved);
1715 assert(_heap->cancelled_gc() ||
1716 _mark_context->is_marked(resolved) && !_heap->in_collection_set(resolved),
1717 "Sanity");
1718 }
1719 }
1720 }
1721
1722 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(narrowOop* p) {
1723 ShouldNotReachHere();
1724 }
1725
1726 size_t ShenandoahEvacUpdateCleanupOopStorageRootsClosure::dead_counter() const {
1727 return _dead_counter;
1728 }
1729
1730 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::reset_dead_counter() {
1731 _dead_counter = 0;
1732 }
1733
1734 class ShenandoahIsCLDAliveClosure : public CLDClosure {
1735 public:
1736 void do_cld(ClassLoaderData* cld) {
1737 cld->is_alive();
1738 }
1739 };
1740
1741 class ShenandoahIsNMethodAliveClosure: public NMethodClosure {
1742 public:
1743 void do_nmethod(nmethod* n) {
1744 n->is_unloading();
1745 }
1746 };
1747
1748 // This task not only evacuates/updates marked weak roots, but also "NULL"
1749 // dead weak roots.
1750 class ShenandoahConcurrentWeakRootsEvacUpdateTask : public AbstractGangTask {
1751 private:
1752 ShenandoahWeakRoot<true /*concurrent*/> _jni_roots;
1753 ShenandoahWeakRoot<true /*concurrent*/> _string_table_roots;
1754 ShenandoahWeakRoot<true /*concurrent*/> _resolved_method_table_roots;
1755 ShenandoahWeakRoot<true /*concurrent*/> _vm_roots;
1756
1757 // Roots related to concurrent class unloading
1758 ShenandoahClassLoaderDataRoots<true /* concurrent */, false /* single thread*/>
1759 _cld_roots;
1760 ShenandoahConcurrentNMethodIterator _nmethod_itr;
1761 bool _concurrent_class_unloading;
1762
1763 public:
1764 ShenandoahConcurrentWeakRootsEvacUpdateTask() :
1765 AbstractGangTask("Shenandoah Concurrent Weak Root Task"),
1766 _jni_roots(OopStorageSet::jni_weak(), ShenandoahPhaseTimings::JNIWeakRoots),
1767 _string_table_roots(OopStorageSet::string_table_weak(), ShenandoahPhaseTimings::StringTableRoots),
1768 _resolved_method_table_roots(OopStorageSet::resolved_method_table_weak(), ShenandoahPhaseTimings::ResolvedMethodTableRoots),
1769 _vm_roots(OopStorageSet::vm_weak(), ShenandoahPhaseTimings::VMWeakRoots),
1770 _nmethod_itr(ShenandoahCodeRoots::table()),
1771 _concurrent_class_unloading(ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1772 StringTable::reset_dead_counter();
1773 ResolvedMethodTable::reset_dead_counter();
1774 if (_concurrent_class_unloading) {
1775 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
1776 _nmethod_itr.nmethods_do_begin();
1777 }
1778 }
1779
1780 ~ShenandoahConcurrentWeakRootsEvacUpdateTask() {
1781 StringTable::finish_dead_counter();
1782 ResolvedMethodTable::finish_dead_counter();
1783 if (_concurrent_class_unloading) {
1784 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
1785 _nmethod_itr.nmethods_do_end();
1786 }
1787 }
1788
1789 void work(uint 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 _jni_roots.oops_do(&cl, worker_id);
1796 _vm_roots.oops_do(&cl, worker_id);
1797
1798 cl.reset_dead_counter();
1799 _string_table_roots.oops_do(&cl, worker_id);
1800 StringTable::inc_dead_counter(cl.dead_counter());
1801
1802 cl.reset_dead_counter();
1803 _resolved_method_table_roots.oops_do(&cl, worker_id);
1804 ResolvedMethodTable::inc_dead_counter(cl.dead_counter());
1805 }
1806
1807 // If we are going to perform concurrent class unloading later on, we need to
1808 // cleanup the weak oops in CLD and determinate nmethod's unloading state, so that we
1809 // can cleanup immediate garbage sooner.
1810 if (_concurrent_class_unloading) {
1811 // Applies ShenandoahIsCLDAlive closure to CLDs, native barrier will either NULL the
1812 // CLD's holder or evacuate it.
1813 ShenandoahIsCLDAliveClosure is_cld_alive;
1814 _cld_roots.cld_do(&is_cld_alive, worker_id);
1815
1816 // Applies ShenandoahIsNMethodAliveClosure to registered nmethods.
1817 // The closure calls nmethod->is_unloading(). The is_unloading
1818 // state is cached, therefore, during concurrent class unloading phase,
1819 // we will not touch the metadata of unloading nmethods
1820 ShenandoahIsNMethodAliveClosure is_nmethod_alive;
1821 _nmethod_itr.nmethods_do(&is_nmethod_alive);
1822 }
1823 }
1824 };
1825
1826 void ShenandoahHeap::op_weak_roots() {
1827 if (is_concurrent_weak_root_in_progress()) {
1828 // Concurrent weak root processing
1829 ShenandoahConcurrentWeakRootsEvacUpdateTask task;
1830 workers()->run_task(&task);
1831 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1832 set_concurrent_weak_root_in_progress(false);
1833 }
1834 }
1835 }
1836
1837 void ShenandoahHeap::op_class_unloading() {
1838 assert (is_concurrent_weak_root_in_progress() &&
1839 ShenandoahConcurrentRoots::should_do_concurrent_class_unloading(),
1840 "Checked by caller");
1841 _unloader.unload();
1842 set_concurrent_weak_root_in_progress(false);
1843 }
1844
1845 void ShenandoahHeap::op_strong_roots() {
1846 assert(is_concurrent_strong_root_in_progress(), "Checked by caller");
1847 ShenandoahConcurrentRootsEvacUpdateTask task;
1848 workers()->run_task(&task);
1849 set_concurrent_strong_root_in_progress(false);
1850 }
1851
1852 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1853 private:
1854 ShenandoahMarkingContext* const _ctx;
1855 public:
1856 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1857
1858 void heap_region_do(ShenandoahHeapRegion* r) {
1859 if (r->is_active()) {
1860 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1861 // anyway to capture any updates that happened since now.
1862 r->clear_live_data();
1863 _ctx->capture_top_at_mark_start(r);
1864 }
1865 }
1866
1867 bool is_thread_safe() { return true; }
1868 };
1869
1870 void ShenandoahHeap::op_reset() {
1871 if (ShenandoahPacing) {
1872 pacer()->setup_for_reset();
1873 }
1874 reset_mark_bitmap();
1875
1876 ShenandoahResetUpdateRegionStateClosure cl;
1877 parallel_heap_region_iterate(&cl);
1878 }
1879
1880 void ShenandoahHeap::op_preclean() {
1881 if (ShenandoahPacing) {
1882 pacer()->setup_for_preclean();
1883 }
1884 concurrent_mark()->preclean_weak_refs();
1885 }
1886
1887 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1888 ShenandoahMetricsSnapshot metrics;
1889 metrics.snap_before();
1890
1891 full_gc()->do_it(cause);
1892 if (UseTLAB) {
1893 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs);
1894 resize_all_tlabs();
1895 }
1896
1897 metrics.snap_after();
1898
1899 if (metrics.is_good_progress()) {
1900 _progress_last_gc.set();
1901 } else {
1902 // Nothing to do. Tell the allocation path that we have failed to make
1903 // progress, and it can finally fail.
1904 _progress_last_gc.unset();
1905 }
1906 }
1907
1908 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1909 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1910 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1911 // some phase, we have to upgrade the Degenerate GC to Full GC.
1912
1913 clear_cancelled_gc();
1914
1915 ShenandoahMetricsSnapshot metrics;
1916 metrics.snap_before();
1917
1918 switch (point) {
1919 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1920 // but enters it at different points, depending on which concurrent phase had
1921 // degenerated.
1922
1923 case _degenerated_outside_cycle:
1924 // We have degenerated from outside the cycle, which means something is bad with
1925 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1926 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1927 // we can do the most aggressive degen cycle, which includes processing references and
1928 // class unloading, unless those features are explicitly disabled.
1929 //
1930 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1931 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1932 set_process_references(heuristics()->can_process_references());
1933 set_unload_classes(heuristics()->can_unload_classes());
1934
1935 op_reset();
1936
1937 op_init_mark();
1938 if (cancelled_gc()) {
1939 op_degenerated_fail();
1940 return;
1941 }
1942
1943 case _degenerated_mark:
1944 op_final_mark();
1945 if (cancelled_gc()) {
1946 op_degenerated_fail();
1947 return;
1948 }
1949
1950 if (!has_forwarded_objects() && ShenandoahConcurrentRoots::can_do_concurrent_class_unloading()) {
1951 // Disarm nmethods that armed for concurrent mark. On normal cycle, it would
1952 // be disarmed while conc-roots phase is running.
1953 // TODO: Call op_conc_roots() here instead
1954 ShenandoahCodeRoots::disarm_nmethods();
1955 }
1956
1957 op_cleanup_early();
1958
1959 case _degenerated_evac:
1960 // If heuristics thinks we should do the cycle, this flag would be set,
1961 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
1962 if (is_evacuation_in_progress()) {
1963
1964 // Degeneration under oom-evac protocol might have left some objects in
1965 // collection set un-evacuated. Restart evacuation from the beginning to
1966 // capture all objects. For all the objects that are already evacuated,
1967 // it would be a simple check, which is supposed to be fast. This is also
1968 // safe to do even without degeneration, as CSet iterator is at beginning
1969 // in preparation for evacuation anyway.
1970 //
1971 // Before doing that, we need to make sure we never had any cset-pinned
1972 // regions. This may happen if allocation failure happened when evacuating
1973 // the about-to-be-pinned object, oom-evac protocol left the object in
1974 // the collection set, and then the pin reached the cset region. If we continue
1975 // the cycle here, we would trash the cset and alive objects in it. To avoid
1976 // it, we fail degeneration right away and slide into Full GC to recover.
1977
1978 {
1979 sync_pinned_region_status();
1980 collection_set()->clear_current_index();
1981
1982 ShenandoahHeapRegion* r;
1983 while ((r = collection_set()->next()) != NULL) {
1984 if (r->is_pinned()) {
1985 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1986 op_degenerated_fail();
1987 return;
1988 }
1989 }
1990
1991 collection_set()->clear_current_index();
1992 }
1993
1994 op_stw_evac();
1995 if (cancelled_gc()) {
1996 op_degenerated_fail();
1997 return;
1998 }
1999 }
2000
2001 // If heuristics thinks we should do the cycle, this flag would be set,
2002 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
2003 if (has_forwarded_objects()) {
2004 op_init_updaterefs();
2005 if (cancelled_gc()) {
2006 op_degenerated_fail();
2007 return;
2008 }
2009 }
2010
2011 case _degenerated_updaterefs:
2012 if (has_forwarded_objects()) {
2013 op_final_updaterefs();
2014 if (cancelled_gc()) {
2015 op_degenerated_fail();
2016 return;
2017 }
2018 }
2019
2020 op_cleanup_complete();
2021 break;
2022
2023 default:
2024 ShouldNotReachHere();
2025 }
2026
2027 if (ShenandoahVerify) {
2028 verifier()->verify_after_degenerated();
2029 }
2030
2031 if (VerifyAfterGC) {
2032 Universe::verify();
2033 }
2034
2035 metrics.snap_after();
2036
2037 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
2038 // because that probably means the heap is overloaded and/or fragmented.
2039 if (!metrics.is_good_progress()) {
2040 _progress_last_gc.unset();
2041 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
2042 op_degenerated_futile();
2043 } else {
2044 _progress_last_gc.set();
2045 }
2046 }
2047
2048 void ShenandoahHeap::op_degenerated_fail() {
2049 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
2050 shenandoah_policy()->record_degenerated_upgrade_to_full();
2051 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2052 }
2053
2054 void ShenandoahHeap::op_degenerated_futile() {
2055 shenandoah_policy()->record_degenerated_upgrade_to_full();
2056 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2057 }
2058
2059 void ShenandoahHeap::force_satb_flush_all_threads() {
2060 if (!is_concurrent_mark_in_progress()) {
2061 // No need to flush SATBs
2062 return;
2063 }
2064
2065 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2066 ShenandoahThreadLocalData::set_force_satb_flush(t, true);
2067 }
2068 // The threads are not "acquiring" their thread-local data, but it does not
2069 // hurt to "release" the updates here anyway.
2070 OrderAccess::fence();
2071 }
2072
2073 void ShenandoahHeap::set_gc_state_all_threads(char state) {
2074 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2075 ShenandoahThreadLocalData::set_gc_state(t, state);
2076 }
2077 }
2078
2079 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
2080 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
2081 _gc_state.set_cond(mask, value);
2082 set_gc_state_all_threads(_gc_state.raw_value());
2083 }
2084
2085 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
2086 if (has_forwarded_objects()) {
2087 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
2088 } else {
2089 set_gc_state_mask(MARKING, in_progress);
2090 }
2091 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
2092 }
2093
2094 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
2095 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
2096 set_gc_state_mask(EVACUATION, in_progress);
2097 }
2098
2099 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
2100 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
2101 if (in_progress) {
2102 _concurrent_strong_root_in_progress.set();
2103 } else {
2104 _concurrent_strong_root_in_progress.unset();
2105 }
2106 }
2107
2108 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool in_progress) {
2109 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
2110 if (in_progress) {
2111 _concurrent_weak_root_in_progress.set();
2112 } else {
2113 _concurrent_weak_root_in_progress.unset();
2114 }
2115 }
2116
2117 void ShenandoahHeap::ref_processing_init() {
2118 assert(_max_workers > 0, "Sanity");
2119
2120 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
2121 bool mt_discovery = _max_workers > 1;
2122
2123 _ref_processor =
2124 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
2125 mt_processing, // MT processing
2126 _max_workers, // Degree of MT processing
2127 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 log_info(gc, init)("Reference processing: %s discovery, %s processing",
2134 mt_discovery ? "parallel" : "serial",
2135 mt_processing ? "parallel" : "serial");
2136
2137 shenandoah_assert_rp_isalive_not_installed();
2138 }
2139
2140 GCTracer* ShenandoahHeap::tracer() {
2141 return shenandoah_policy()->tracer();
2142 }
2143
2144 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
2145 return _free_set->used();
2146 }
2147
2148 bool ShenandoahHeap::try_cancel_gc() {
2149 while (true) {
2150 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
2151 if (prev == CANCELLABLE) return true;
2152 else if (prev == CANCELLED) return false;
2153 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
2154 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
2155 if (Thread::current()->is_Java_thread()) {
2156 // We need to provide a safepoint here, otherwise we might
2157 // spin forever if a SP is pending.
2158 ThreadBlockInVM sp(JavaThread::current());
2159 SpinPause();
2160 }
2161 }
2162 }
2163
2164 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
2165 if (try_cancel_gc()) {
2166 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
2167 log_info(gc)("%s", msg.buffer());
2168 Events::log(Thread::current(), "%s", msg.buffer());
2169 }
2170 }
2171
2172 uint ShenandoahHeap::max_workers() {
2173 return _max_workers;
2174 }
2175
2176 void ShenandoahHeap::stop() {
2177 // The shutdown sequence should be able to terminate when GC is running.
2178
2179 // Step 0. Notify policy to disable event recording.
2180 _shenandoah_policy->record_shutdown();
2181
2182 // Step 1. Notify control thread that we are in shutdown.
2183 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
2184 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
2185 control_thread()->prepare_for_graceful_shutdown();
2186
2187 // Step 2. Notify GC workers that we are cancelling GC.
2188 cancel_gc(GCCause::_shenandoah_stop_vm);
2189
2190 // Step 3. Wait until GC worker exits normally.
2191 control_thread()->stop();
2192
2193 // Step 4. Stop String Dedup thread if it is active
2194 if (ShenandoahStringDedup::is_enabled()) {
2195 ShenandoahStringDedup::stop();
2196 }
2197 }
2198
2199 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
2200 if (!unload_classes()) return;
2201
2202 // Unload classes and purge SystemDictionary.
2203 {
2204 ShenandoahGCSubPhase phase(full_gc ?
2205 ShenandoahPhaseTimings::full_gc_purge_class_unload :
2206 ShenandoahPhaseTimings::purge_class_unload);
2207 bool purged_class = SystemDictionary::do_unloading(gc_timer());
2208
2209 ShenandoahIsAliveSelector is_alive;
2210 uint num_workers = _workers->active_workers();
2211 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
2212 _workers->run_task(&unlink_task);
2213 }
2214
2215 {
2216 ShenandoahGCSubPhase phase(full_gc ?
2217 ShenandoahPhaseTimings::full_gc_purge_cldg :
2218 ShenandoahPhaseTimings::purge_cldg);
2219 ClassLoaderDataGraph::purge();
2220 }
2221 // Resize and verify metaspace
2222 MetaspaceGC::compute_new_size();
2223 MetaspaceUtils::verify_metrics();
2224 }
2225
2226 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
2227 // so they should not have forwarded oops.
2228 // However, we do need to "null" dead oops in the roots, if can not be done
2229 // in concurrent cycles.
2230 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
2231 ShenandoahGCSubPhase root_phase(full_gc ?
2232 ShenandoahPhaseTimings::full_gc_purge :
2233 ShenandoahPhaseTimings::purge);
2234 uint num_workers = _workers->active_workers();
2235 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
2236 ShenandoahPhaseTimings::full_gc_purge_weak_par :
2237 ShenandoahPhaseTimings::purge_weak_par;
2238 ShenandoahGCSubPhase phase(timing_phase);
2239 ShenandoahGCWorkerPhase worker_phase(timing_phase);
2240
2241 // Cleanup weak roots
2242 if (has_forwarded_objects()) {
2243 ShenandoahForwardedIsAliveClosure is_alive;
2244 ShenandoahUpdateRefsClosure keep_alive;
2245 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2246 cleaning_task(&is_alive, &keep_alive, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2247 _workers->run_task(&cleaning_task);
2248 } else {
2249 ShenandoahIsAliveClosure is_alive;
2250 #ifdef ASSERT
2251 ShenandoahAssertNotForwardedClosure verify_cl;
2252 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2253 cleaning_task(&is_alive, &verify_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2254 #else
2255 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2256 cleaning_task(&is_alive, &do_nothing_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2257 #endif
2258 _workers->run_task(&cleaning_task);
2259 }
2260 }
2261
2262 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2263 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2264 stw_process_weak_roots(full_gc);
2265 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2266 stw_unload_classes(full_gc);
2267 }
2268 }
2269
2270 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2271 set_gc_state_mask(HAS_FORWARDED, cond);
2272 }
2273
2274 void ShenandoahHeap::set_process_references(bool pr) {
2275 _process_references.set_cond(pr);
2276 }
2277
2278 void ShenandoahHeap::set_unload_classes(bool uc) {
2279 _unload_classes.set_cond(uc);
2280 }
2281
2282 bool ShenandoahHeap::process_references() const {
2283 return _process_references.is_set();
2284 }
2285
2286 bool ShenandoahHeap::unload_classes() const {
2287 return _unload_classes.is_set();
2288 }
2289
2290 address ShenandoahHeap::in_cset_fast_test_addr() {
2291 ShenandoahHeap* heap = ShenandoahHeap::heap();
2292 assert(heap->collection_set() != NULL, "Sanity");
2293 return (address) heap->collection_set()->biased_map_address();
2294 }
2295
2296 address ShenandoahHeap::cancelled_gc_addr() {
2297 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
2298 }
2299
2300 address ShenandoahHeap::gc_state_addr() {
2301 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2302 }
2303
2304 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2305 return Atomic::load_acquire(&_bytes_allocated_since_gc_start);
2306 }
2307
2308 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2309 Atomic::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2310 }
2311
2312 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2313 _degenerated_gc_in_progress.set_cond(in_progress);
2314 }
2315
2316 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2317 _full_gc_in_progress.set_cond(in_progress);
2318 }
2319
2320 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2321 assert (is_full_gc_in_progress(), "should be");
2322 _full_gc_move_in_progress.set_cond(in_progress);
2323 }
2324
2325 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2326 set_gc_state_mask(UPDATEREFS, in_progress);
2327 }
2328
2329 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2330 ShenandoahCodeRoots::register_nmethod(nm);
2331 }
2332
2333 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2334 ShenandoahCodeRoots::unregister_nmethod(nm);
2335 }
2336
2337 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
2338 ShenandoahCodeRoots::flush_nmethod(nm);
2339 }
2340
2341 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2342 heap_region_containing(o)->record_pin();
2343 return o;
2344 }
2345
2346 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2347 heap_region_containing(o)->record_unpin();
2348 }
2349
2350 void ShenandoahHeap::sync_pinned_region_status() {
2351 ShenandoahHeapLocker locker(lock());
2352
2353 for (size_t i = 0; i < num_regions(); i++) {
2354 ShenandoahHeapRegion *r = get_region(i);
2355 if (r->is_active()) {
2356 if (r->is_pinned()) {
2357 if (r->pin_count() == 0) {
2358 r->make_unpinned();
2359 }
2360 } else {
2361 if (r->pin_count() > 0) {
2362 r->make_pinned();
2363 }
2364 }
2365 }
2366 }
2367
2368 assert_pinned_region_status();
2369 }
2370
2371 #ifdef ASSERT
2372 void ShenandoahHeap::assert_pinned_region_status() {
2373 for (size_t i = 0; i < num_regions(); i++) {
2374 ShenandoahHeapRegion* r = get_region(i);
2375 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2376 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2377 }
2378 }
2379 #endif
2380
2381 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
2382 return _gc_timer;
2383 }
2384
2385 void ShenandoahHeap::prepare_concurrent_roots() {
2386 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2387 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
2388 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
2389 set_concurrent_weak_root_in_progress(true);
2390 }
2391 }
2392
2393 void ShenandoahHeap::prepare_concurrent_unloading() {
2394 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2395 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2396 _unloader.prepare();
2397 }
2398 }
2399
2400 void ShenandoahHeap::finish_concurrent_unloading() {
2401 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2402 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2403 _unloader.finish();
2404 }
2405 }
2406
2407 #ifdef ASSERT
2408 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2409 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2410
2411 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2412 if (UseDynamicNumberOfGCThreads) {
2413 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2414 } else {
2415 // Use ParallelGCThreads inside safepoints
2416 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
2417 }
2418 } else {
2419 if (UseDynamicNumberOfGCThreads) {
2420 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2421 } else {
2422 // Use ConcGCThreads outside safepoints
2423 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2424 }
2425 }
2426 }
2427 #endif
2428
2429 ShenandoahVerifier* ShenandoahHeap::verifier() {
2430 guarantee(ShenandoahVerify, "Should be enabled");
2431 assert (_verifier != NULL, "sanity");
2432 return _verifier;
2433 }
2434
2435 template<class T>
2436 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2437 private:
2438 T cl;
2439 ShenandoahHeap* _heap;
2440 ShenandoahRegionIterator* _regions;
2441 bool _concurrent;
2442 public:
2443 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2444 AbstractGangTask("Concurrent Update References Task"),
2445 cl(T()),
2446 _heap(ShenandoahHeap::heap()),
2447 _regions(regions),
2448 _concurrent(concurrent) {
2449 }
2450
2451 void work(uint worker_id) {
2452 if (_concurrent) {
2453 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2454 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2455 do_work();
2456 } else {
2457 ShenandoahParallelWorkerSession worker_session(worker_id);
2458 do_work();
2459 }
2460 }
2461
2462 private:
2463 void do_work() {
2464 ShenandoahHeapRegion* r = _regions->next();
2465 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2466 while (r != NULL) {
2467 HeapWord* update_watermark = r->get_update_watermark();
2468 assert (update_watermark >= r->bottom(), "sanity");
2469 if (r->is_active() && !r->is_cset()) {
2470 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2471 }
2472 if (ShenandoahPacing) {
2473 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2474 }
2475 if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
2476 return;
2477 }
2478 r = _regions->next();
2479 }
2480 }
2481 };
2482
2483 void ShenandoahHeap::update_heap_references(bool concurrent) {
2484 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
2485 workers()->run_task(&task);
2486 }
2487
2488 void ShenandoahHeap::op_init_updaterefs() {
2489 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2490
2491 set_evacuation_in_progress(false);
2492
2493 {
2494 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::init_update_refs_retire_gclabs);
2495 retire_and_reset_gclabs();
2496 }
2497
2498 if (ShenandoahVerify) {
2499 if (!is_degenerated_gc_in_progress()) {
2500 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2501 }
2502 verifier()->verify_before_updaterefs();
2503 }
2504
2505 set_update_refs_in_progress(true);
2506
2507 _update_refs_iterator.reset();
2508
2509 if (ShenandoahPacing) {
2510 pacer()->setup_for_updaterefs();
2511 }
2512 }
2513
2514 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2515 private:
2516 ShenandoahHeapLock* const _lock;
2517
2518 public:
2519 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2520
2521 void heap_region_do(ShenandoahHeapRegion* r) {
2522 // Drop unnecessary "pinned" state from regions that does not have CP marks
2523 // anymore, as this would allow trashing them.
2524
2525 if (r->is_active()) {
2526 if (r->is_pinned()) {
2527 if (r->pin_count() == 0) {
2528 ShenandoahHeapLocker locker(_lock);
2529 r->make_unpinned();
2530 }
2531 } else {
2532 if (r->pin_count() > 0) {
2533 ShenandoahHeapLocker locker(_lock);
2534 r->make_pinned();
2535 }
2536 }
2537 }
2538 }
2539
2540 bool is_thread_safe() { return true; }
2541 };
2542
2543 void ShenandoahHeap::op_final_updaterefs() {
2544 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2545
2546 finish_concurrent_unloading();
2547
2548 // Check if there is left-over work, and finish it
2549 if (_update_refs_iterator.has_next()) {
2550 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2551
2552 // Finish updating references where we left off.
2553 clear_cancelled_gc();
2554 update_heap_references(false);
2555 }
2556
2557 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2558 // everything. On degenerated paths, cancelled gc would not be set anyway.
2559 if (cancelled_gc()) {
2560 clear_cancelled_gc();
2561 }
2562 assert(!cancelled_gc(), "Should have been done right before");
2563
2564 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2565 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2566 }
2567
2568 if (is_degenerated_gc_in_progress()) {
2569 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2570 } else {
2571 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2572 }
2573
2574 // Has to be done before cset is clear
2575 if (ShenandoahVerify) {
2576 verifier()->verify_roots_in_to_space();
2577 }
2578
2579 {
2580 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::final_update_refs_update_region_states);
2581 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2582 parallel_heap_region_iterate(&cl);
2583
2584 assert_pinned_region_status();
2585 }
2586
2587 {
2588 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2589 trash_cset_regions();
2590 }
2591
2592 set_has_forwarded_objects(false);
2593 set_update_refs_in_progress(false);
2594
2595 if (ShenandoahVerify) {
2596 verifier()->verify_after_updaterefs();
2597 }
2598
2599 if (VerifyAfterGC) {
2600 Universe::verify();
2601 }
2602
2603 {
2604 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::final_update_refs_rebuild_freeset);
2605 ShenandoahHeapLocker locker(lock());
2606 _free_set->rebuild();
2607 }
2608 }
2609
2610 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2611 print_on(st);
2612 print_heap_regions_on(st);
2613 }
2614
2615 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2616 size_t slice = r->index() / _bitmap_regions_per_slice;
2617
2618 size_t regions_from = _bitmap_regions_per_slice * slice;
2619 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2620 for (size_t g = regions_from; g < regions_to; g++) {
2621 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2622 if (skip_self && g == r->index()) continue;
2623 if (get_region(g)->is_committed()) {
2624 return true;
2625 }
2626 }
2627 return false;
2628 }
2629
2630 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2631 shenandoah_assert_heaplocked();
2632
2633 // Bitmaps in special regions do not need commits
2634 if (_bitmap_region_special) {
2635 return true;
2636 }
2637
2638 if (is_bitmap_slice_committed(r, true)) {
2639 // Some other region from the group is already committed, meaning the bitmap
2640 // slice is already committed, we exit right away.
2641 return true;
2642 }
2643
2644 // Commit the bitmap slice:
2645 size_t slice = r->index() / _bitmap_regions_per_slice;
2646 size_t off = _bitmap_bytes_per_slice * slice;
2647 size_t len = _bitmap_bytes_per_slice;
2648 if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) {
2649 return false;
2650 }
2651 return true;
2652 }
2653
2654 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2655 shenandoah_assert_heaplocked();
2656
2657 // Bitmaps in special regions do not need uncommits
2658 if (_bitmap_region_special) {
2659 return true;
2660 }
2661
2662 if (is_bitmap_slice_committed(r, true)) {
2663 // Some other region from the group is still committed, meaning the bitmap
2664 // slice is should stay committed, exit right away.
2665 return true;
2666 }
2667
2668 // Uncommit the bitmap slice:
2669 size_t slice = r->index() / _bitmap_regions_per_slice;
2670 size_t off = _bitmap_bytes_per_slice * slice;
2671 size_t len = _bitmap_bytes_per_slice;
2672 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2673 return false;
2674 }
2675 return true;
2676 }
2677
2678 void ShenandoahHeap::safepoint_synchronize_begin() {
2679 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2680 SuspendibleThreadSet::synchronize();
2681 }
2682 }
2683
2684 void ShenandoahHeap::safepoint_synchronize_end() {
2685 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2686 SuspendibleThreadSet::desynchronize();
2687 }
2688 }
2689
2690 void ShenandoahHeap::vmop_entry_init_mark() {
2691 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2692 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
2693
2694 try_inject_alloc_failure();
2695 VM_ShenandoahInitMark op;
2696 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2697 }
2698
2699 void ShenandoahHeap::vmop_entry_final_mark() {
2700 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2701 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
2702
2703 try_inject_alloc_failure();
2704 VM_ShenandoahFinalMarkStartEvac op;
2705 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2706 }
2707
2708 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2709 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2710 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
2711
2712 try_inject_alloc_failure();
2713 VM_ShenandoahInitUpdateRefs op;
2714 VMThread::execute(&op);
2715 }
2716
2717 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2718 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2719 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
2720
2721 try_inject_alloc_failure();
2722 VM_ShenandoahFinalUpdateRefs op;
2723 VMThread::execute(&op);
2724 }
2725
2726 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2727 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2728 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
2729
2730 try_inject_alloc_failure();
2731 VM_ShenandoahFullGC op(cause);
2732 VMThread::execute(&op);
2733 }
2734
2735 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2736 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2737 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
2738
2739 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2740 VMThread::execute(°enerated_gc);
2741 }
2742
2743 void ShenandoahHeap::entry_init_mark() {
2744 const char* msg = init_mark_event_message();
2745 ShenandoahPausePhase gc_phase(msg);
2746 EventMark em("%s", msg);
2747
2748 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
2749
2750 ShenandoahWorkerScope scope(workers(),
2751 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2752 "init marking");
2753
2754 op_init_mark();
2755 }
2756
2757 void ShenandoahHeap::entry_final_mark() {
2758 const char* msg = final_mark_event_message();
2759 ShenandoahPausePhase gc_phase(msg);
2760 EventMark em("%s", msg);
2761
2762 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
2763
2764 ShenandoahWorkerScope scope(workers(),
2765 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2766 "final marking");
2767
2768 op_final_mark();
2769 }
2770
2771 void ShenandoahHeap::entry_init_updaterefs() {
2772 static const char* msg = "Pause Init Update Refs";
2773 ShenandoahPausePhase gc_phase(msg);
2774 EventMark em("%s", msg);
2775
2776 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
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);
2786 EventMark em("%s", msg);
2787
2788 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
2789
2790 ShenandoahWorkerScope scope(workers(),
2791 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2792 "final reference update");
2793
2794 op_final_updaterefs();
2795 }
2796
2797 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2798 static const char* msg = "Pause Full";
2799 ShenandoahPausePhase gc_phase(msg, true /* log_heap_usage */);
2800 EventMark em("%s", msg);
2801
2802 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
2803
2804 ShenandoahWorkerScope scope(workers(),
2805 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2806 "full gc");
2807
2808 op_full(cause);
2809 }
2810
2811 void ShenandoahHeap::entry_degenerated(int point) {
2812 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2813 const char* msg = degen_event_message(dpoint);
2814 ShenandoahPausePhase gc_phase(msg, true /* log_heap_usage */);
2815 EventMark em("%s", msg);
2816
2817 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
2818
2819 ShenandoahWorkerScope scope(workers(),
2820 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2821 "stw degenerated gc");
2822
2823 set_degenerated_gc_in_progress(true);
2824 op_degenerated(dpoint);
2825 set_degenerated_gc_in_progress(false);
2826 }
2827
2828 void ShenandoahHeap::entry_mark() {
2829 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2830
2831 const char* msg = conc_mark_event_message();
2832 ShenandoahConcurrentPhase gc_phase(msg);
2833 EventMark em("%s", msg);
2834
2835 ShenandoahGCPhase conc_mark_phase(ShenandoahPhaseTimings::conc_mark);
2836
2837 ShenandoahWorkerScope scope(workers(),
2838 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2839 "concurrent marking");
2840
2841 try_inject_alloc_failure();
2842 op_mark();
2843 }
2844
2845 void ShenandoahHeap::entry_evac() {
2846 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2847
2848 static const char* msg = "Concurrent evacuation";
2849 ShenandoahConcurrentPhase gc_phase(msg);
2850 EventMark em("%s", msg);
2851
2852 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
2853
2854 ShenandoahWorkerScope scope(workers(),
2855 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2856 "concurrent evacuation");
2857
2858 try_inject_alloc_failure();
2859 op_conc_evac();
2860 }
2861
2862 void ShenandoahHeap::entry_updaterefs() {
2863 static const char* msg = "Concurrent update references";
2864 ShenandoahConcurrentPhase gc_phase(msg);
2865 EventMark em("%s", msg);
2866
2867 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
2868
2869 ShenandoahWorkerScope scope(workers(),
2870 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2871 "concurrent reference update");
2872
2873 try_inject_alloc_failure();
2874 op_updaterefs();
2875 }
2876
2877 void ShenandoahHeap::entry_weak_roots() {
2878 static const char* msg = "Concurrent weak roots";
2879 ShenandoahConcurrentPhase gc_phase(msg);
2880 EventMark em("%s", msg);
2881
2882 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_weak_roots);
2883
2884 ShenandoahWorkerScope scope(workers(),
2885 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2886 "concurrent weak root");
2887
2888 try_inject_alloc_failure();
2889 op_weak_roots();
2890 }
2891
2892 void ShenandoahHeap::entry_class_unloading() {
2893 static const char* msg = "Concurrent class unloading";
2894 ShenandoahConcurrentPhase gc_phase(msg);
2895 EventMark em("%s", msg);
2896
2897 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_class_unloading);
2898
2899 ShenandoahWorkerScope scope(workers(),
2900 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2901 "concurrent class unloading");
2902
2903 try_inject_alloc_failure();
2904 op_class_unloading();
2905 }
2906
2907 void ShenandoahHeap::entry_strong_roots() {
2908 static const char* msg = "Concurrent strong roots";
2909 ShenandoahConcurrentPhase gc_phase(msg);
2910 EventMark em("%s", msg);
2911
2912 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_strong_roots);
2913
2914 ShenandoahWorkerScope scope(workers(),
2915 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2916 "concurrent strong root");
2917
2918 try_inject_alloc_failure();
2919 op_strong_roots();
2920 }
2921
2922 void ShenandoahHeap::entry_cleanup_early() {
2923 static const char* msg = "Concurrent cleanup";
2924 ShenandoahConcurrentPhase gc_phase(msg, true /* log_heap_usage */);
2925 EventMark em("%s", msg);
2926
2927 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::conc_cleanup_early);
2928
2929 // This phase does not use workers, no need for setup
2930
2931 try_inject_alloc_failure();
2932 op_cleanup_early();
2933 }
2934
2935 void ShenandoahHeap::entry_cleanup_complete() {
2936 static const char* msg = "Concurrent cleanup";
2937 ShenandoahConcurrentPhase gc_phase(msg, true /* log_heap_usage */);
2938 EventMark em("%s", msg);
2939
2940 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::conc_cleanup_complete);
2941
2942 // This phase does not use workers, no need for setup
2943
2944 try_inject_alloc_failure();
2945 op_cleanup_complete();
2946 }
2947
2948 void ShenandoahHeap::entry_reset() {
2949 static const char* msg = "Concurrent reset";
2950 ShenandoahConcurrentPhase gc_phase(msg);
2951 EventMark em("%s", msg);
2952
2953 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::conc_reset);
2954
2955 ShenandoahWorkerScope scope(workers(),
2956 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2957 "concurrent reset");
2958
2959 try_inject_alloc_failure();
2960 op_reset();
2961 }
2962
2963 void ShenandoahHeap::entry_preclean() {
2964 if (ShenandoahPreclean && process_references()) {
2965 static const char* msg = "Concurrent precleaning";
2966 ShenandoahConcurrentPhase gc_phase(msg);
2967 EventMark em("%s", msg);
2968
2969 ShenandoahGCSubPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
2970
2971 ShenandoahWorkerScope scope(workers(),
2972 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2973 "concurrent preclean",
2974 /* check_workers = */ false);
2975
2976 try_inject_alloc_failure();
2977 op_preclean();
2978 }
2979 }
2980
2981 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2982 static const char *msg = "Concurrent uncommit";
2983 ShenandoahConcurrentPhase gc_phase(msg, true /* log_heap_usage */);
2984 EventMark em("%s", msg);
2985
2986 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::conc_uncommit);
2987
2988 op_uncommit(shrink_before);
2989 }
2990
2991 void ShenandoahHeap::try_inject_alloc_failure() {
2992 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2993 _inject_alloc_failure.set();
2994 os::naked_short_sleep(1);
2995 if (cancelled_gc()) {
2996 log_info(gc)("Allocation failure was successfully injected");
2997 }
2998 }
2999 }
3000
3001 bool ShenandoahHeap::should_inject_alloc_failure() {
3002 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
3003 }
3004
3005 void ShenandoahHeap::initialize_serviceability() {
3006 _memory_pool = new ShenandoahMemoryPool(this);
3007 _cycle_memory_manager.add_pool(_memory_pool);
3008 _stw_memory_manager.add_pool(_memory_pool);
3009 }
3010
3011 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
3012 GrowableArray<GCMemoryManager*> memory_managers(2);
3013 memory_managers.append(&_cycle_memory_manager);
3014 memory_managers.append(&_stw_memory_manager);
3015 return memory_managers;
3016 }
3017
3018 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
3019 GrowableArray<MemoryPool*> memory_pools(1);
3020 memory_pools.append(_memory_pool);
3021 return memory_pools;
3022 }
3023
3024 MemoryUsage ShenandoahHeap::memory_usage() {
3025 return _memory_pool->get_memory_usage();
3026 }
3027
3028 void ShenandoahHeap::enter_evacuation() {
3029 _oom_evac_handler.enter_evacuation();
3030 }
3031
3032 void ShenandoahHeap::leave_evacuation() {
3033 _oom_evac_handler.leave_evacuation();
3034 }
3035
3036 ShenandoahRegionIterator::ShenandoahRegionIterator() :
3037 _heap(ShenandoahHeap::heap()),
3038 _index(0) {}
3039
3040 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
3041 _heap(heap),
3042 _index(0) {}
3043
3044 void ShenandoahRegionIterator::reset() {
3045 _index = 0;
3046 }
3047
3048 bool ShenandoahRegionIterator::has_next() const {
3049 return _index < _heap->num_regions();
3050 }
3051
3052 char ShenandoahHeap::gc_state() const {
3053 return _gc_state.raw_value();
3054 }
3055
3056 void ShenandoahHeap::deduplicate_string(oop str) {
3057 assert(java_lang_String::is_instance(str), "invariant");
3058
3059 if (ShenandoahStringDedup::is_enabled()) {
3060 ShenandoahStringDedup::deduplicate(str);
3061 }
3062 }
3063
3064 const char* ShenandoahHeap::init_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 "Pause Init Mark (process weakrefs) (unload classes)";
3072 } else if (proc_refs) {
3073 return "Pause Init Mark (process weakrefs)";
3074 } else if (unload_cls) {
3075 return "Pause Init Mark (unload classes)";
3076 } else {
3077 return "Pause Init Mark";
3078 }
3079 }
3080
3081 const char* ShenandoahHeap::final_mark_event_message() const {
3082 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3083
3084 bool proc_refs = process_references();
3085 bool unload_cls = unload_classes();
3086
3087 if (proc_refs && unload_cls) {
3088 return "Pause Final Mark (process weakrefs) (unload classes)";
3089 } else if (proc_refs) {
3090 return "Pause Final Mark (process weakrefs)";
3091 } else if (unload_cls) {
3092 return "Pause Final Mark (unload classes)";
3093 } else {
3094 return "Pause Final Mark";
3095 }
3096 }
3097
3098 const char* ShenandoahHeap::conc_mark_event_message() const {
3099 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3100
3101 bool proc_refs = process_references();
3102 bool unload_cls = unload_classes();
3103
3104 if (proc_refs && unload_cls) {
3105 return "Concurrent marking (process weakrefs) (unload classes)";
3106 } else if (proc_refs) {
3107 return "Concurrent marking (process weakrefs)";
3108 } else if (unload_cls) {
3109 return "Concurrent marking (unload classes)";
3110 } else {
3111 return "Concurrent marking";
3112 }
3113 }
3114
3115 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
3116 switch (point) {
3117 case _degenerated_unset:
3118 return "Pause Degenerated GC (<UNSET>)";
3119 case _degenerated_outside_cycle:
3120 return "Pause Degenerated GC (Outside of Cycle)";
3121 case _degenerated_mark:
3122 return "Pause Degenerated GC (Mark)";
3123 case _degenerated_evac:
3124 return "Pause Degenerated GC (Evacuation)";
3125 case _degenerated_updaterefs:
3126 return "Pause Degenerated GC (Update Refs)";
3127 default:
3128 ShouldNotReachHere();
3129 return "ERROR";
3130 }
3131 }
3132
3133 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
3134 #ifdef ASSERT
3135 assert(_liveness_cache != NULL, "sanity");
3136 assert(worker_id < _max_workers, "sanity");
3137 for (uint i = 0; i < num_regions(); i++) {
3138 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
3139 }
3140 #endif
3141 return _liveness_cache[worker_id];
3142 }
3143
3144 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
3145 assert(worker_id < _max_workers, "sanity");
3146 assert(_liveness_cache != NULL, "sanity");
3147 ShenandoahLiveData* ld = _liveness_cache[worker_id];
3148 for (uint i = 0; i < num_regions(); i++) {
3149 ShenandoahLiveData live = ld[i];
3150 if (live > 0) {
3151 ShenandoahHeapRegion* r = get_region(i);
3152 r->increase_live_data_gc_words(live);
3153 ld[i] = 0;
3154 }
3155 }
3156 }