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(max_workers());
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(ShenandoahPhaseTimings::Phase phase) :
1649 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Strong Roots Task"),
1650 _vm_roots(phase),
1651 _cld_roots(phase) {}
1652
1653 void work(uint worker_id) {
1654 ShenandoahEvacOOMScope oom;
1655 {
1656 // vm_roots and weak_roots are OopStorage backed roots, concurrent iteration
1657 // may race against OopStorage::release() calls.
1658 ShenandoahEvacUpdateOopStorageRootsClosure cl;
1659 _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl, worker_id);
1660 }
1661
1662 {
1663 ShenandoahEvacuateUpdateRootsClosure<> cl;
1664 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1665 _cld_roots.cld_do(&clds, worker_id);
1666 }
1667
1668 {
1669 ShenandoahForwardedIsAliveClosure is_alive;
1670 ShenandoahEvacuateUpdateRootsClosure<MO_RELEASE> keep_alive;
1671 _dedup_roots.oops_do(&is_alive, &keep_alive, worker_id);
1672 }
1673 }
1674 };
1675
1676 class ShenandoahEvacUpdateCleanupOopStorageRootsClosure : public BasicOopIterateClosure {
1677 private:
1678 ShenandoahHeap* const _heap;
1679 ShenandoahMarkingContext* const _mark_context;
1680 bool _evac_in_progress;
1681 Thread* const _thread;
1682 size_t _dead_counter;
1683
1684 public:
1685 ShenandoahEvacUpdateCleanupOopStorageRootsClosure();
1686 void do_oop(oop* p);
1687 void do_oop(narrowOop* p);
1688
1689 size_t dead_counter() const;
1690 void reset_dead_counter();
1691 };
1692
1693 ShenandoahEvacUpdateCleanupOopStorageRootsClosure::ShenandoahEvacUpdateCleanupOopStorageRootsClosure() :
1694 _heap(ShenandoahHeap::heap()),
1695 _mark_context(ShenandoahHeap::heap()->marking_context()),
1696 _evac_in_progress(ShenandoahHeap::heap()->is_evacuation_in_progress()),
1697 _thread(Thread::current()),
1698 _dead_counter(0) {
1699 }
1700
1701 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(oop* p) {
1702 const oop obj = RawAccess<>::oop_load(p);
1703 if (!CompressedOops::is_null(obj)) {
1704 if (!_mark_context->is_marked(obj)) {
1705 shenandoah_assert_correct(p, obj);
1706 oop old = Atomic::cmpxchg(p, obj, oop(NULL));
1707 if (obj == old) {
1708 _dead_counter ++;
1709 }
1710 } else if (_evac_in_progress && _heap->in_collection_set(obj)) {
1711 oop resolved = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1712 if (resolved == obj) {
1713 resolved = _heap->evacuate_object(obj, _thread);
1714 }
1715 Atomic::cmpxchg(p, obj, resolved);
1716 assert(_heap->cancelled_gc() ||
1717 _mark_context->is_marked(resolved) && !_heap->in_collection_set(resolved),
1718 "Sanity");
1719 }
1720 }
1721 }
1722
1723 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(narrowOop* p) {
1724 ShouldNotReachHere();
1725 }
1726
1727 size_t ShenandoahEvacUpdateCleanupOopStorageRootsClosure::dead_counter() const {
1728 return _dead_counter;
1729 }
1730
1731 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::reset_dead_counter() {
1732 _dead_counter = 0;
1733 }
1734
1735 class ShenandoahIsCLDAliveClosure : public CLDClosure {
1736 public:
1737 void do_cld(ClassLoaderData* cld) {
1738 cld->is_alive();
1739 }
1740 };
1741
1742 class ShenandoahIsNMethodAliveClosure: public NMethodClosure {
1743 public:
1744 void do_nmethod(nmethod* n) {
1745 n->is_unloading();
1746 }
1747 };
1748
1749 // This task not only evacuates/updates marked weak roots, but also "NULL"
1750 // dead weak roots.
1751 class ShenandoahConcurrentWeakRootsEvacUpdateTask : public AbstractGangTask {
1752 private:
1753 ShenandoahWeakRoot<true /*concurrent*/> _jni_roots;
1754 ShenandoahWeakRoot<true /*concurrent*/> _string_table_roots;
1755 ShenandoahWeakRoot<true /*concurrent*/> _resolved_method_table_roots;
1756 ShenandoahWeakRoot<true /*concurrent*/> _vm_roots;
1757
1758 // Roots related to concurrent class unloading
1759 ShenandoahClassLoaderDataRoots<true /* concurrent */, false /* single thread*/>
1760 _cld_roots;
1761 ShenandoahConcurrentNMethodIterator _nmethod_itr;
1762 bool _concurrent_class_unloading;
1763
1764 public:
1765 ShenandoahConcurrentWeakRootsEvacUpdateTask(ShenandoahPhaseTimings::Phase phase) :
1766 AbstractGangTask("Shenandoah Concurrent Weak Root Task"),
1767 _jni_roots(OopStorageSet::jni_weak(), phase, ShenandoahPhaseTimings::JNIWeakRoots),
1768 _string_table_roots(OopStorageSet::string_table_weak(), phase, ShenandoahPhaseTimings::StringTableRoots),
1769 _resolved_method_table_roots(OopStorageSet::resolved_method_table_weak(), phase, ShenandoahPhaseTimings::ResolvedMethodTableRoots),
1770 _vm_roots(OopStorageSet::vm_weak(), phase, ShenandoahPhaseTimings::VMWeakRoots),
1771 _cld_roots(phase),
1772 _nmethod_itr(ShenandoahCodeRoots::table()),
1773 _concurrent_class_unloading(ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1774 StringTable::reset_dead_counter();
1775 ResolvedMethodTable::reset_dead_counter();
1776 if (_concurrent_class_unloading) {
1777 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
1778 _nmethod_itr.nmethods_do_begin();
1779 }
1780 }
1781
1782 ~ShenandoahConcurrentWeakRootsEvacUpdateTask() {
1783 StringTable::finish_dead_counter();
1784 ResolvedMethodTable::finish_dead_counter();
1785 if (_concurrent_class_unloading) {
1786 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
1787 _nmethod_itr.nmethods_do_end();
1788 }
1789 }
1790
1791 void work(uint worker_id) {
1792 {
1793 ShenandoahEvacOOMScope oom;
1794 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
1795 // may race against OopStorage::release() calls.
1796 ShenandoahEvacUpdateCleanupOopStorageRootsClosure cl;
1797 _jni_roots.oops_do(&cl, worker_id);
1798 _vm_roots.oops_do(&cl, worker_id);
1799
1800 cl.reset_dead_counter();
1801 _string_table_roots.oops_do(&cl, worker_id);
1802 StringTable::inc_dead_counter(cl.dead_counter());
1803
1804 cl.reset_dead_counter();
1805 _resolved_method_table_roots.oops_do(&cl, worker_id);
1806 ResolvedMethodTable::inc_dead_counter(cl.dead_counter());
1807 }
1808
1809 // If we are going to perform concurrent class unloading later on, we need to
1810 // cleanup the weak oops in CLD and determinate nmethod's unloading state, so that we
1811 // can cleanup immediate garbage sooner.
1812 if (_concurrent_class_unloading) {
1813 // Applies ShenandoahIsCLDAlive closure to CLDs, native barrier will either NULL the
1814 // CLD's holder or evacuate it.
1815 ShenandoahIsCLDAliveClosure is_cld_alive;
1816 _cld_roots.cld_do(&is_cld_alive, worker_id);
1817
1818 // Applies ShenandoahIsNMethodAliveClosure to registered nmethods.
1819 // The closure calls nmethod->is_unloading(). The is_unloading
1820 // state is cached, therefore, during concurrent class unloading phase,
1821 // we will not touch the metadata of unloading nmethods
1822 ShenandoahIsNMethodAliveClosure is_nmethod_alive;
1823 _nmethod_itr.nmethods_do(&is_nmethod_alive);
1824 }
1825 }
1826 };
1827
1828 void ShenandoahHeap::op_weak_roots() {
1829 if (is_concurrent_weak_root_in_progress()) {
1830 // Concurrent weak root processing
1831 ShenandoahConcurrentWeakRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_weak_roots);
1832 workers()->run_task(&task);
1833 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1834 set_concurrent_weak_root_in_progress(false);
1835 }
1836 }
1837 }
1838
1839 void ShenandoahHeap::op_class_unloading() {
1840 assert (is_concurrent_weak_root_in_progress() &&
1841 ShenandoahConcurrentRoots::should_do_concurrent_class_unloading(),
1842 "Checked by caller");
1843 _unloader.unload();
1844 set_concurrent_weak_root_in_progress(false);
1845 }
1846
1847 void ShenandoahHeap::op_strong_roots() {
1848 assert(is_concurrent_strong_root_in_progress(), "Checked by caller");
1849 ShenandoahConcurrentRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_strong_roots);
1850 workers()->run_task(&task);
1851 set_concurrent_strong_root_in_progress(false);
1852 }
1853
1854 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1855 private:
1856 ShenandoahMarkingContext* const _ctx;
1857 public:
1858 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1859
1860 void heap_region_do(ShenandoahHeapRegion* r) {
1861 if (r->is_active()) {
1862 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1863 // anyway to capture any updates that happened since now.
1864 r->clear_live_data();
1865 _ctx->capture_top_at_mark_start(r);
1866 }
1867 }
1868
1869 bool is_thread_safe() { return true; }
1870 };
1871
1872 void ShenandoahHeap::op_reset() {
1873 if (ShenandoahPacing) {
1874 pacer()->setup_for_reset();
1875 }
1876 reset_mark_bitmap();
1877
1878 ShenandoahResetUpdateRegionStateClosure cl;
1879 parallel_heap_region_iterate(&cl);
1880 }
1881
1882 void ShenandoahHeap::op_preclean() {
1883 if (ShenandoahPacing) {
1884 pacer()->setup_for_preclean();
1885 }
1886 concurrent_mark()->preclean_weak_refs();
1887 }
1888
1889 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1890 ShenandoahMetricsSnapshot metrics;
1891 metrics.snap_before();
1892
1893 full_gc()->do_it(cause);
1894 if (UseTLAB) {
1895 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs);
1896 resize_all_tlabs();
1897 }
1898
1899 metrics.snap_after();
1900
1901 if (metrics.is_good_progress()) {
1902 _progress_last_gc.set();
1903 } else {
1904 // Nothing to do. Tell the allocation path that we have failed to make
1905 // progress, and it can finally fail.
1906 _progress_last_gc.unset();
1907 }
1908 }
1909
1910 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1911 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1912 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1913 // some phase, we have to upgrade the Degenerate GC to Full GC.
1914
1915 clear_cancelled_gc();
1916
1917 ShenandoahMetricsSnapshot metrics;
1918 metrics.snap_before();
1919
1920 switch (point) {
1921 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1922 // but enters it at different points, depending on which concurrent phase had
1923 // degenerated.
1924
1925 case _degenerated_outside_cycle:
1926 // We have degenerated from outside the cycle, which means something is bad with
1927 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1928 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1929 // we can do the most aggressive degen cycle, which includes processing references and
1930 // class unloading, unless those features are explicitly disabled.
1931 //
1932 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1933 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1934 set_process_references(heuristics()->can_process_references());
1935 set_unload_classes(heuristics()->can_unload_classes());
1936
1937 op_reset();
1938
1939 op_init_mark();
1940 if (cancelled_gc()) {
1941 op_degenerated_fail();
1942 return;
1943 }
1944
1945 case _degenerated_mark:
1946 op_final_mark();
1947 if (cancelled_gc()) {
1948 op_degenerated_fail();
1949 return;
1950 }
1951
1952 if (!has_forwarded_objects() && ShenandoahConcurrentRoots::can_do_concurrent_class_unloading()) {
1953 // Disarm nmethods that armed for concurrent mark. On normal cycle, it would
1954 // be disarmed while conc-roots phase is running.
1955 // TODO: Call op_conc_roots() here instead
1956 ShenandoahCodeRoots::disarm_nmethods();
1957 }
1958
1959 op_cleanup_early();
1960
1961 case _degenerated_evac:
1962 // If heuristics thinks we should do the cycle, this flag would be set,
1963 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
1964 if (is_evacuation_in_progress()) {
1965
1966 // Degeneration under oom-evac protocol might have left some objects in
1967 // collection set un-evacuated. Restart evacuation from the beginning to
1968 // capture all objects. For all the objects that are already evacuated,
1969 // it would be a simple check, which is supposed to be fast. This is also
1970 // safe to do even without degeneration, as CSet iterator is at beginning
1971 // in preparation for evacuation anyway.
1972 //
1973 // Before doing that, we need to make sure we never had any cset-pinned
1974 // regions. This may happen if allocation failure happened when evacuating
1975 // the about-to-be-pinned object, oom-evac protocol left the object in
1976 // the collection set, and then the pin reached the cset region. If we continue
1977 // the cycle here, we would trash the cset and alive objects in it. To avoid
1978 // it, we fail degeneration right away and slide into Full GC to recover.
1979
1980 {
1981 sync_pinned_region_status();
1982 collection_set()->clear_current_index();
1983
1984 ShenandoahHeapRegion* r;
1985 while ((r = collection_set()->next()) != NULL) {
1986 if (r->is_pinned()) {
1987 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1988 op_degenerated_fail();
1989 return;
1990 }
1991 }
1992
1993 collection_set()->clear_current_index();
1994 }
1995
1996 op_stw_evac();
1997 if (cancelled_gc()) {
1998 op_degenerated_fail();
1999 return;
2000 }
2001 }
2002
2003 // If heuristics thinks we should do the cycle, this flag would be set,
2004 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
2005 if (has_forwarded_objects()) {
2006 op_init_updaterefs();
2007 if (cancelled_gc()) {
2008 op_degenerated_fail();
2009 return;
2010 }
2011 }
2012
2013 case _degenerated_updaterefs:
2014 if (has_forwarded_objects()) {
2015 op_final_updaterefs();
2016 if (cancelled_gc()) {
2017 op_degenerated_fail();
2018 return;
2019 }
2020 }
2021
2022 op_cleanup_complete();
2023 break;
2024
2025 default:
2026 ShouldNotReachHere();
2027 }
2028
2029 if (ShenandoahVerify) {
2030 verifier()->verify_after_degenerated();
2031 }
2032
2033 if (VerifyAfterGC) {
2034 Universe::verify();
2035 }
2036
2037 metrics.snap_after();
2038
2039 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
2040 // because that probably means the heap is overloaded and/or fragmented.
2041 if (!metrics.is_good_progress()) {
2042 _progress_last_gc.unset();
2043 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
2044 op_degenerated_futile();
2045 } else {
2046 _progress_last_gc.set();
2047 }
2048 }
2049
2050 void ShenandoahHeap::op_degenerated_fail() {
2051 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
2052 shenandoah_policy()->record_degenerated_upgrade_to_full();
2053 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2054 }
2055
2056 void ShenandoahHeap::op_degenerated_futile() {
2057 shenandoah_policy()->record_degenerated_upgrade_to_full();
2058 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2059 }
2060
2061 void ShenandoahHeap::force_satb_flush_all_threads() {
2062 if (!is_concurrent_mark_in_progress()) {
2063 // No need to flush SATBs
2064 return;
2065 }
2066
2067 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2068 ShenandoahThreadLocalData::set_force_satb_flush(t, true);
2069 }
2070 // The threads are not "acquiring" their thread-local data, but it does not
2071 // hurt to "release" the updates here anyway.
2072 OrderAccess::fence();
2073 }
2074
2075 void ShenandoahHeap::set_gc_state_all_threads(char state) {
2076 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2077 ShenandoahThreadLocalData::set_gc_state(t, state);
2078 }
2079 }
2080
2081 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
2082 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
2083 _gc_state.set_cond(mask, value);
2084 set_gc_state_all_threads(_gc_state.raw_value());
2085 }
2086
2087 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
2088 if (has_forwarded_objects()) {
2089 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
2090 } else {
2091 set_gc_state_mask(MARKING, in_progress);
2092 }
2093 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
2094 }
2095
2096 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
2097 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
2098 set_gc_state_mask(EVACUATION, in_progress);
2099 }
2100
2101 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
2102 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
2103 if (in_progress) {
2104 _concurrent_strong_root_in_progress.set();
2105 } else {
2106 _concurrent_strong_root_in_progress.unset();
2107 }
2108 }
2109
2110 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool in_progress) {
2111 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
2112 if (in_progress) {
2113 _concurrent_weak_root_in_progress.set();
2114 } else {
2115 _concurrent_weak_root_in_progress.unset();
2116 }
2117 }
2118
2119 void ShenandoahHeap::ref_processing_init() {
2120 assert(_max_workers > 0, "Sanity");
2121
2122 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
2123 bool mt_discovery = _max_workers > 1;
2124
2125 _ref_processor =
2126 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
2127 mt_processing, // MT processing
2128 _max_workers, // Degree of MT processing
2129 mt_discovery, // MT discovery
2130 _max_workers, // Degree of MT discovery
2131 false, // Reference discovery is not atomic
2132 NULL, // No closure, should be installed before use
2133 true); // Scale worker threads
2134
2135 log_info(gc, init)("Reference processing: %s discovery, %s processing",
2136 mt_discovery ? "parallel" : "serial",
2137 mt_processing ? "parallel" : "serial");
2138
2139 shenandoah_assert_rp_isalive_not_installed();
2140 }
2141
2142 GCTracer* ShenandoahHeap::tracer() {
2143 return shenandoah_policy()->tracer();
2144 }
2145
2146 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
2147 return _free_set->used();
2148 }
2149
2150 bool ShenandoahHeap::try_cancel_gc() {
2151 while (true) {
2152 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
2153 if (prev == CANCELLABLE) return true;
2154 else if (prev == CANCELLED) return false;
2155 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
2156 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
2157 if (Thread::current()->is_Java_thread()) {
2158 // We need to provide a safepoint here, otherwise we might
2159 // spin forever if a SP is pending.
2160 ThreadBlockInVM sp(JavaThread::current());
2161 SpinPause();
2162 }
2163 }
2164 }
2165
2166 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
2167 if (try_cancel_gc()) {
2168 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
2169 log_info(gc)("%s", msg.buffer());
2170 Events::log(Thread::current(), "%s", msg.buffer());
2171 }
2172 }
2173
2174 uint ShenandoahHeap::max_workers() {
2175 return _max_workers;
2176 }
2177
2178 void ShenandoahHeap::stop() {
2179 // The shutdown sequence should be able to terminate when GC is running.
2180
2181 // Step 0. Notify policy to disable event recording.
2182 _shenandoah_policy->record_shutdown();
2183
2184 // Step 1. Notify control thread that we are in shutdown.
2185 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
2186 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
2187 control_thread()->prepare_for_graceful_shutdown();
2188
2189 // Step 2. Notify GC workers that we are cancelling GC.
2190 cancel_gc(GCCause::_shenandoah_stop_vm);
2191
2192 // Step 3. Wait until GC worker exits normally.
2193 control_thread()->stop();
2194
2195 // Step 4. Stop String Dedup thread if it is active
2196 if (ShenandoahStringDedup::is_enabled()) {
2197 ShenandoahStringDedup::stop();
2198 }
2199 }
2200
2201 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
2202 if (!unload_classes()) return;
2203
2204 // Unload classes and purge SystemDictionary.
2205 {
2206 ShenandoahGCSubPhase phase(full_gc ?
2207 ShenandoahPhaseTimings::full_gc_purge_class_unload :
2208 ShenandoahPhaseTimings::purge_class_unload);
2209 bool purged_class = SystemDictionary::do_unloading(gc_timer());
2210
2211 ShenandoahIsAliveSelector is_alive;
2212 uint num_workers = _workers->active_workers();
2213 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
2214 _workers->run_task(&unlink_task);
2215 }
2216
2217 {
2218 ShenandoahGCSubPhase phase(full_gc ?
2219 ShenandoahPhaseTimings::full_gc_purge_cldg :
2220 ShenandoahPhaseTimings::purge_cldg);
2221 ClassLoaderDataGraph::purge();
2222 }
2223 // Resize and verify metaspace
2224 MetaspaceGC::compute_new_size();
2225 MetaspaceUtils::verify_metrics();
2226 }
2227
2228 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
2229 // so they should not have forwarded oops.
2230 // However, we do need to "null" dead oops in the roots, if can not be done
2231 // in concurrent cycles.
2232 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
2233 ShenandoahGCSubPhase root_phase(full_gc ?
2234 ShenandoahPhaseTimings::full_gc_purge :
2235 ShenandoahPhaseTimings::purge);
2236 uint num_workers = _workers->active_workers();
2237 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
2238 ShenandoahPhaseTimings::full_gc_purge_weak_par :
2239 ShenandoahPhaseTimings::purge_weak_par;
2240 ShenandoahGCSubPhase phase(timing_phase);
2241 ShenandoahGCWorkerPhase worker_phase(timing_phase);
2242
2243 // Cleanup weak roots
2244 if (has_forwarded_objects()) {
2245 ShenandoahForwardedIsAliveClosure is_alive;
2246 ShenandoahUpdateRefsClosure keep_alive;
2247 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2248 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2249 _workers->run_task(&cleaning_task);
2250 } else {
2251 ShenandoahIsAliveClosure is_alive;
2252 #ifdef ASSERT
2253 ShenandoahAssertNotForwardedClosure verify_cl;
2254 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2255 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2256 #else
2257 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2258 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2259 #endif
2260 _workers->run_task(&cleaning_task);
2261 }
2262 }
2263
2264 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2265 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2266 stw_process_weak_roots(full_gc);
2267 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2268 stw_unload_classes(full_gc);
2269 }
2270 }
2271
2272 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2273 set_gc_state_mask(HAS_FORWARDED, cond);
2274 }
2275
2276 void ShenandoahHeap::set_process_references(bool pr) {
2277 _process_references.set_cond(pr);
2278 }
2279
2280 void ShenandoahHeap::set_unload_classes(bool uc) {
2281 _unload_classes.set_cond(uc);
2282 }
2283
2284 bool ShenandoahHeap::process_references() const {
2285 return _process_references.is_set();
2286 }
2287
2288 bool ShenandoahHeap::unload_classes() const {
2289 return _unload_classes.is_set();
2290 }
2291
2292 address ShenandoahHeap::in_cset_fast_test_addr() {
2293 ShenandoahHeap* heap = ShenandoahHeap::heap();
2294 assert(heap->collection_set() != NULL, "Sanity");
2295 return (address) heap->collection_set()->biased_map_address();
2296 }
2297
2298 address ShenandoahHeap::cancelled_gc_addr() {
2299 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
2300 }
2301
2302 address ShenandoahHeap::gc_state_addr() {
2303 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2304 }
2305
2306 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2307 return Atomic::load_acquire(&_bytes_allocated_since_gc_start);
2308 }
2309
2310 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2311 Atomic::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2312 }
2313
2314 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2315 _degenerated_gc_in_progress.set_cond(in_progress);
2316 }
2317
2318 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2319 _full_gc_in_progress.set_cond(in_progress);
2320 }
2321
2322 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2323 assert (is_full_gc_in_progress(), "should be");
2324 _full_gc_move_in_progress.set_cond(in_progress);
2325 }
2326
2327 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2328 set_gc_state_mask(UPDATEREFS, in_progress);
2329 }
2330
2331 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2332 ShenandoahCodeRoots::register_nmethod(nm);
2333 }
2334
2335 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2336 ShenandoahCodeRoots::unregister_nmethod(nm);
2337 }
2338
2339 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
2340 ShenandoahCodeRoots::flush_nmethod(nm);
2341 }
2342
2343 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2344 heap_region_containing(o)->record_pin();
2345 return o;
2346 }
2347
2348 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2349 heap_region_containing(o)->record_unpin();
2350 }
2351
2352 void ShenandoahHeap::sync_pinned_region_status() {
2353 ShenandoahHeapLocker locker(lock());
2354
2355 for (size_t i = 0; i < num_regions(); i++) {
2356 ShenandoahHeapRegion *r = get_region(i);
2357 if (r->is_active()) {
2358 if (r->is_pinned()) {
2359 if (r->pin_count() == 0) {
2360 r->make_unpinned();
2361 }
2362 } else {
2363 if (r->pin_count() > 0) {
2364 r->make_pinned();
2365 }
2366 }
2367 }
2368 }
2369
2370 assert_pinned_region_status();
2371 }
2372
2373 #ifdef ASSERT
2374 void ShenandoahHeap::assert_pinned_region_status() {
2375 for (size_t i = 0; i < num_regions(); i++) {
2376 ShenandoahHeapRegion* r = get_region(i);
2377 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2378 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2379 }
2380 }
2381 #endif
2382
2383 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
2384 return _gc_timer;
2385 }
2386
2387 void ShenandoahHeap::prepare_concurrent_roots() {
2388 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2389 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
2390 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
2391 set_concurrent_weak_root_in_progress(true);
2392 }
2393 }
2394
2395 void ShenandoahHeap::prepare_concurrent_unloading() {
2396 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2397 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2398 _unloader.prepare();
2399 }
2400 }
2401
2402 void ShenandoahHeap::finish_concurrent_unloading() {
2403 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2404 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2405 _unloader.finish();
2406 }
2407 }
2408
2409 #ifdef ASSERT
2410 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2411 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2412
2413 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2414 if (UseDynamicNumberOfGCThreads) {
2415 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2416 } else {
2417 // Use ParallelGCThreads inside safepoints
2418 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
2419 }
2420 } else {
2421 if (UseDynamicNumberOfGCThreads) {
2422 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2423 } else {
2424 // Use ConcGCThreads outside safepoints
2425 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2426 }
2427 }
2428 }
2429 #endif
2430
2431 ShenandoahVerifier* ShenandoahHeap::verifier() {
2432 guarantee(ShenandoahVerify, "Should be enabled");
2433 assert (_verifier != NULL, "sanity");
2434 return _verifier;
2435 }
2436
2437 template<class T>
2438 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2439 private:
2440 T cl;
2441 ShenandoahHeap* _heap;
2442 ShenandoahRegionIterator* _regions;
2443 bool _concurrent;
2444 public:
2445 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2446 AbstractGangTask("Concurrent Update References Task"),
2447 cl(T()),
2448 _heap(ShenandoahHeap::heap()),
2449 _regions(regions),
2450 _concurrent(concurrent) {
2451 }
2452
2453 void work(uint worker_id) {
2454 if (_concurrent) {
2455 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2456 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2457 do_work();
2458 } else {
2459 ShenandoahParallelWorkerSession worker_session(worker_id);
2460 do_work();
2461 }
2462 }
2463
2464 private:
2465 void do_work() {
2466 ShenandoahHeapRegion* r = _regions->next();
2467 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2468 while (r != NULL) {
2469 HeapWord* update_watermark = r->get_update_watermark();
2470 assert (update_watermark >= r->bottom(), "sanity");
2471 if (r->is_active() && !r->is_cset()) {
2472 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2473 }
2474 if (ShenandoahPacing) {
2475 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2476 }
2477 if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
2478 return;
2479 }
2480 r = _regions->next();
2481 }
2482 }
2483 };
2484
2485 void ShenandoahHeap::update_heap_references(bool concurrent) {
2486 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
2487 workers()->run_task(&task);
2488 }
2489
2490 void ShenandoahHeap::op_init_updaterefs() {
2491 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2492
2493 set_evacuation_in_progress(false);
2494
2495 {
2496 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::init_update_refs_retire_gclabs);
2497 retire_and_reset_gclabs();
2498 }
2499
2500 if (ShenandoahVerify) {
2501 if (!is_degenerated_gc_in_progress()) {
2502 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2503 }
2504 verifier()->verify_before_updaterefs();
2505 }
2506
2507 set_update_refs_in_progress(true);
2508
2509 _update_refs_iterator.reset();
2510
2511 if (ShenandoahPacing) {
2512 pacer()->setup_for_updaterefs();
2513 }
2514 }
2515
2516 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2517 private:
2518 ShenandoahHeapLock* const _lock;
2519
2520 public:
2521 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2522
2523 void heap_region_do(ShenandoahHeapRegion* r) {
2524 // Drop unnecessary "pinned" state from regions that does not have CP marks
2525 // anymore, as this would allow trashing them.
2526
2527 if (r->is_active()) {
2528 if (r->is_pinned()) {
2529 if (r->pin_count() == 0) {
2530 ShenandoahHeapLocker locker(_lock);
2531 r->make_unpinned();
2532 }
2533 } else {
2534 if (r->pin_count() > 0) {
2535 ShenandoahHeapLocker locker(_lock);
2536 r->make_pinned();
2537 }
2538 }
2539 }
2540 }
2541
2542 bool is_thread_safe() { return true; }
2543 };
2544
2545 void ShenandoahHeap::op_final_updaterefs() {
2546 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2547
2548 finish_concurrent_unloading();
2549
2550 // Check if there is left-over work, and finish it
2551 if (_update_refs_iterator.has_next()) {
2552 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2553
2554 // Finish updating references where we left off.
2555 clear_cancelled_gc();
2556 update_heap_references(false);
2557 }
2558
2559 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2560 // everything. On degenerated paths, cancelled gc would not be set anyway.
2561 if (cancelled_gc()) {
2562 clear_cancelled_gc();
2563 }
2564 assert(!cancelled_gc(), "Should have been done right before");
2565
2566 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2567 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2568 }
2569
2570 if (is_degenerated_gc_in_progress()) {
2571 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2572 } else {
2573 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2574 }
2575
2576 // Has to be done before cset is clear
2577 if (ShenandoahVerify) {
2578 verifier()->verify_roots_in_to_space();
2579 }
2580
2581 {
2582 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::final_update_refs_update_region_states);
2583 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2584 parallel_heap_region_iterate(&cl);
2585
2586 assert_pinned_region_status();
2587 }
2588
2589 {
2590 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2591 trash_cset_regions();
2592 }
2593
2594 set_has_forwarded_objects(false);
2595 set_update_refs_in_progress(false);
2596
2597 if (ShenandoahVerify) {
2598 verifier()->verify_after_updaterefs();
2599 }
2600
2601 if (VerifyAfterGC) {
2602 Universe::verify();
2603 }
2604
2605 {
2606 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::final_update_refs_rebuild_freeset);
2607 ShenandoahHeapLocker locker(lock());
2608 _free_set->rebuild();
2609 }
2610 }
2611
2612 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2613 print_on(st);
2614 print_heap_regions_on(st);
2615 }
2616
2617 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2618 size_t slice = r->index() / _bitmap_regions_per_slice;
2619
2620 size_t regions_from = _bitmap_regions_per_slice * slice;
2621 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2622 for (size_t g = regions_from; g < regions_to; g++) {
2623 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2624 if (skip_self && g == r->index()) continue;
2625 if (get_region(g)->is_committed()) {
2626 return true;
2627 }
2628 }
2629 return false;
2630 }
2631
2632 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2633 shenandoah_assert_heaplocked();
2634
2635 // Bitmaps in special regions do not need commits
2636 if (_bitmap_region_special) {
2637 return true;
2638 }
2639
2640 if (is_bitmap_slice_committed(r, true)) {
2641 // Some other region from the group is already committed, meaning the bitmap
2642 // slice is already committed, we exit right away.
2643 return true;
2644 }
2645
2646 // Commit the bitmap slice:
2647 size_t slice = r->index() / _bitmap_regions_per_slice;
2648 size_t off = _bitmap_bytes_per_slice * slice;
2649 size_t len = _bitmap_bytes_per_slice;
2650 if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) {
2651 return false;
2652 }
2653 return true;
2654 }
2655
2656 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2657 shenandoah_assert_heaplocked();
2658
2659 // Bitmaps in special regions do not need uncommits
2660 if (_bitmap_region_special) {
2661 return true;
2662 }
2663
2664 if (is_bitmap_slice_committed(r, true)) {
2665 // Some other region from the group is still committed, meaning the bitmap
2666 // slice is should stay committed, exit right away.
2667 return true;
2668 }
2669
2670 // Uncommit the bitmap slice:
2671 size_t slice = r->index() / _bitmap_regions_per_slice;
2672 size_t off = _bitmap_bytes_per_slice * slice;
2673 size_t len = _bitmap_bytes_per_slice;
2674 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2675 return false;
2676 }
2677 return true;
2678 }
2679
2680 void ShenandoahHeap::safepoint_synchronize_begin() {
2681 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2682 SuspendibleThreadSet::synchronize();
2683 }
2684 }
2685
2686 void ShenandoahHeap::safepoint_synchronize_end() {
2687 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2688 SuspendibleThreadSet::desynchronize();
2689 }
2690 }
2691
2692 void ShenandoahHeap::vmop_entry_init_mark() {
2693 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2694 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
2695
2696 try_inject_alloc_failure();
2697 VM_ShenandoahInitMark op;
2698 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2699 }
2700
2701 void ShenandoahHeap::vmop_entry_final_mark() {
2702 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2703 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
2704
2705 try_inject_alloc_failure();
2706 VM_ShenandoahFinalMarkStartEvac op;
2707 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2708 }
2709
2710 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2711 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2712 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
2713
2714 try_inject_alloc_failure();
2715 VM_ShenandoahInitUpdateRefs op;
2716 VMThread::execute(&op);
2717 }
2718
2719 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2720 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2721 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
2722
2723 try_inject_alloc_failure();
2724 VM_ShenandoahFinalUpdateRefs op;
2725 VMThread::execute(&op);
2726 }
2727
2728 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2729 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2730 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
2731
2732 try_inject_alloc_failure();
2733 VM_ShenandoahFullGC op(cause);
2734 VMThread::execute(&op);
2735 }
2736
2737 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2738 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2739 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
2740
2741 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2742 VMThread::execute(°enerated_gc);
2743 }
2744
2745 void ShenandoahHeap::entry_init_mark() {
2746 const char* msg = init_mark_event_message();
2747 ShenandoahPausePhase gc_phase(msg);
2748 EventMark em("%s", msg);
2749
2750 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
2751
2752 ShenandoahWorkerScope scope(workers(),
2753 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2754 "init marking");
2755
2756 op_init_mark();
2757 }
2758
2759 void ShenandoahHeap::entry_final_mark() {
2760 const char* msg = final_mark_event_message();
2761 ShenandoahPausePhase gc_phase(msg);
2762 EventMark em("%s", msg);
2763
2764 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
2765
2766 ShenandoahWorkerScope scope(workers(),
2767 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2768 "final marking");
2769
2770 op_final_mark();
2771 }
2772
2773 void ShenandoahHeap::entry_init_updaterefs() {
2774 static const char* msg = "Pause Init Update Refs";
2775 ShenandoahPausePhase gc_phase(msg);
2776 EventMark em("%s", msg);
2777
2778 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
2779
2780 // No workers used in this phase, no setup required
2781
2782 op_init_updaterefs();
2783 }
2784
2785 void ShenandoahHeap::entry_final_updaterefs() {
2786 static const char* msg = "Pause Final Update Refs";
2787 ShenandoahPausePhase gc_phase(msg);
2788 EventMark em("%s", msg);
2789
2790 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
2791
2792 ShenandoahWorkerScope scope(workers(),
2793 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2794 "final reference update");
2795
2796 op_final_updaterefs();
2797 }
2798
2799 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2800 static const char* msg = "Pause Full";
2801 ShenandoahPausePhase gc_phase(msg, true /* log_heap_usage */);
2802 EventMark em("%s", msg);
2803
2804 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
2805
2806 ShenandoahWorkerScope scope(workers(),
2807 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2808 "full gc");
2809
2810 op_full(cause);
2811 }
2812
2813 void ShenandoahHeap::entry_degenerated(int point) {
2814 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2815 const char* msg = degen_event_message(dpoint);
2816 ShenandoahPausePhase gc_phase(msg, true /* log_heap_usage */);
2817 EventMark em("%s", msg);
2818
2819 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
2820
2821 ShenandoahWorkerScope scope(workers(),
2822 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2823 "stw degenerated gc");
2824
2825 set_degenerated_gc_in_progress(true);
2826 op_degenerated(dpoint);
2827 set_degenerated_gc_in_progress(false);
2828 }
2829
2830 void ShenandoahHeap::entry_mark() {
2831 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2832
2833 const char* msg = conc_mark_event_message();
2834 ShenandoahConcurrentPhase gc_phase(msg);
2835 EventMark em("%s", msg);
2836
2837 ShenandoahGCPhase conc_mark_phase(ShenandoahPhaseTimings::conc_mark);
2838
2839 ShenandoahWorkerScope scope(workers(),
2840 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2841 "concurrent marking");
2842
2843 try_inject_alloc_failure();
2844 op_mark();
2845 }
2846
2847 void ShenandoahHeap::entry_evac() {
2848 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2849
2850 static const char* msg = "Concurrent evacuation";
2851 ShenandoahConcurrentPhase gc_phase(msg);
2852 EventMark em("%s", msg);
2853
2854 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
2855
2856 ShenandoahWorkerScope scope(workers(),
2857 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2858 "concurrent evacuation");
2859
2860 try_inject_alloc_failure();
2861 op_conc_evac();
2862 }
2863
2864 void ShenandoahHeap::entry_updaterefs() {
2865 static const char* msg = "Concurrent update references";
2866 ShenandoahConcurrentPhase gc_phase(msg);
2867 EventMark em("%s", msg);
2868
2869 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
2870
2871 ShenandoahWorkerScope scope(workers(),
2872 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2873 "concurrent reference update");
2874
2875 try_inject_alloc_failure();
2876 op_updaterefs();
2877 }
2878
2879 void ShenandoahHeap::entry_weak_roots() {
2880 static const char* msg = "Concurrent weak roots";
2881 ShenandoahConcurrentPhase gc_phase(msg);
2882 EventMark em("%s", msg);
2883
2884 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_weak_roots);
2885 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_weak_roots);
2886
2887 ShenandoahWorkerScope scope(workers(),
2888 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2889 "concurrent weak root");
2890
2891 try_inject_alloc_failure();
2892 op_weak_roots();
2893 }
2894
2895 void ShenandoahHeap::entry_class_unloading() {
2896 static const char* msg = "Concurrent class unloading";
2897 ShenandoahConcurrentPhase gc_phase(msg);
2898 EventMark em("%s", msg);
2899
2900 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_class_unloading);
2901
2902 ShenandoahWorkerScope scope(workers(),
2903 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2904 "concurrent class unloading");
2905
2906 try_inject_alloc_failure();
2907 op_class_unloading();
2908 }
2909
2910 void ShenandoahHeap::entry_strong_roots() {
2911 static const char* msg = "Concurrent strong roots";
2912 ShenandoahConcurrentPhase gc_phase(msg);
2913 EventMark em("%s", msg);
2914
2915 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_strong_roots);
2916 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_strong_roots);
2917
2918 ShenandoahWorkerScope scope(workers(),
2919 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2920 "concurrent strong root");
2921
2922 try_inject_alloc_failure();
2923 op_strong_roots();
2924 }
2925
2926 void ShenandoahHeap::entry_cleanup_early() {
2927 static const char* msg = "Concurrent cleanup";
2928 ShenandoahConcurrentPhase gc_phase(msg, true /* log_heap_usage */);
2929 EventMark em("%s", msg);
2930
2931 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::conc_cleanup_early);
2932
2933 // This phase does not use workers, no need for setup
2934
2935 try_inject_alloc_failure();
2936 op_cleanup_early();
2937 }
2938
2939 void ShenandoahHeap::entry_cleanup_complete() {
2940 static const char* msg = "Concurrent cleanup";
2941 ShenandoahConcurrentPhase gc_phase(msg, true /* log_heap_usage */);
2942 EventMark em("%s", msg);
2943
2944 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::conc_cleanup_complete);
2945
2946 // This phase does not use workers, no need for setup
2947
2948 try_inject_alloc_failure();
2949 op_cleanup_complete();
2950 }
2951
2952 void ShenandoahHeap::entry_reset() {
2953 static const char* msg = "Concurrent reset";
2954 ShenandoahConcurrentPhase gc_phase(msg);
2955 EventMark em("%s", msg);
2956
2957 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::conc_reset);
2958
2959 ShenandoahWorkerScope scope(workers(),
2960 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2961 "concurrent reset");
2962
2963 try_inject_alloc_failure();
2964 op_reset();
2965 }
2966
2967 void ShenandoahHeap::entry_preclean() {
2968 if (ShenandoahPreclean && process_references()) {
2969 static const char* msg = "Concurrent precleaning";
2970 ShenandoahConcurrentPhase gc_phase(msg);
2971 EventMark em("%s", msg);
2972
2973 ShenandoahGCSubPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
2974
2975 ShenandoahWorkerScope scope(workers(),
2976 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2977 "concurrent preclean",
2978 /* check_workers = */ false);
2979
2980 try_inject_alloc_failure();
2981 op_preclean();
2982 }
2983 }
2984
2985 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2986 static const char *msg = "Concurrent uncommit";
2987 ShenandoahConcurrentPhase gc_phase(msg, true /* log_heap_usage */);
2988 EventMark em("%s", msg);
2989
2990 ShenandoahGCSubPhase phase(ShenandoahPhaseTimings::conc_uncommit);
2991
2992 op_uncommit(shrink_before);
2993 }
2994
2995 void ShenandoahHeap::try_inject_alloc_failure() {
2996 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2997 _inject_alloc_failure.set();
2998 os::naked_short_sleep(1);
2999 if (cancelled_gc()) {
3000 log_info(gc)("Allocation failure was successfully injected");
3001 }
3002 }
3003 }
3004
3005 bool ShenandoahHeap::should_inject_alloc_failure() {
3006 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
3007 }
3008
3009 void ShenandoahHeap::initialize_serviceability() {
3010 _memory_pool = new ShenandoahMemoryPool(this);
3011 _cycle_memory_manager.add_pool(_memory_pool);
3012 _stw_memory_manager.add_pool(_memory_pool);
3013 }
3014
3015 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
3016 GrowableArray<GCMemoryManager*> memory_managers(2);
3017 memory_managers.append(&_cycle_memory_manager);
3018 memory_managers.append(&_stw_memory_manager);
3019 return memory_managers;
3020 }
3021
3022 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
3023 GrowableArray<MemoryPool*> memory_pools(1);
3024 memory_pools.append(_memory_pool);
3025 return memory_pools;
3026 }
3027
3028 MemoryUsage ShenandoahHeap::memory_usage() {
3029 return _memory_pool->get_memory_usage();
3030 }
3031
3032 void ShenandoahHeap::enter_evacuation() {
3033 _oom_evac_handler.enter_evacuation();
3034 }
3035
3036 void ShenandoahHeap::leave_evacuation() {
3037 _oom_evac_handler.leave_evacuation();
3038 }
3039
3040 ShenandoahRegionIterator::ShenandoahRegionIterator() :
3041 _heap(ShenandoahHeap::heap()),
3042 _index(0) {}
3043
3044 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
3045 _heap(heap),
3046 _index(0) {}
3047
3048 void ShenandoahRegionIterator::reset() {
3049 _index = 0;
3050 }
3051
3052 bool ShenandoahRegionIterator::has_next() const {
3053 return _index < _heap->num_regions();
3054 }
3055
3056 char ShenandoahHeap::gc_state() const {
3057 return _gc_state.raw_value();
3058 }
3059
3060 void ShenandoahHeap::deduplicate_string(oop str) {
3061 assert(java_lang_String::is_instance(str), "invariant");
3062
3063 if (ShenandoahStringDedup::is_enabled()) {
3064 ShenandoahStringDedup::deduplicate(str);
3065 }
3066 }
3067
3068 const char* ShenandoahHeap::init_mark_event_message() const {
3069 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3070
3071 bool proc_refs = process_references();
3072 bool unload_cls = unload_classes();
3073
3074 if (proc_refs && unload_cls) {
3075 return "Pause Init Mark (process weakrefs) (unload classes)";
3076 } else if (proc_refs) {
3077 return "Pause Init Mark (process weakrefs)";
3078 } else if (unload_cls) {
3079 return "Pause Init Mark (unload classes)";
3080 } else {
3081 return "Pause Init Mark";
3082 }
3083 }
3084
3085 const char* ShenandoahHeap::final_mark_event_message() const {
3086 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3087
3088 bool proc_refs = process_references();
3089 bool unload_cls = unload_classes();
3090
3091 if (proc_refs && unload_cls) {
3092 return "Pause Final Mark (process weakrefs) (unload classes)";
3093 } else if (proc_refs) {
3094 return "Pause Final Mark (process weakrefs)";
3095 } else if (unload_cls) {
3096 return "Pause Final Mark (unload classes)";
3097 } else {
3098 return "Pause Final Mark";
3099 }
3100 }
3101
3102 const char* ShenandoahHeap::conc_mark_event_message() const {
3103 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3104
3105 bool proc_refs = process_references();
3106 bool unload_cls = unload_classes();
3107
3108 if (proc_refs && unload_cls) {
3109 return "Concurrent marking (process weakrefs) (unload classes)";
3110 } else if (proc_refs) {
3111 return "Concurrent marking (process weakrefs)";
3112 } else if (unload_cls) {
3113 return "Concurrent marking (unload classes)";
3114 } else {
3115 return "Concurrent marking";
3116 }
3117 }
3118
3119 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
3120 switch (point) {
3121 case _degenerated_unset:
3122 return "Pause Degenerated GC (<UNSET>)";
3123 case _degenerated_outside_cycle:
3124 return "Pause Degenerated GC (Outside of Cycle)";
3125 case _degenerated_mark:
3126 return "Pause Degenerated GC (Mark)";
3127 case _degenerated_evac:
3128 return "Pause Degenerated GC (Evacuation)";
3129 case _degenerated_updaterefs:
3130 return "Pause Degenerated GC (Update Refs)";
3131 default:
3132 ShouldNotReachHere();
3133 return "ERROR";
3134 }
3135 }
3136
3137 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
3138 #ifdef ASSERT
3139 assert(_liveness_cache != NULL, "sanity");
3140 assert(worker_id < _max_workers, "sanity");
3141 for (uint i = 0; i < num_regions(); i++) {
3142 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
3143 }
3144 #endif
3145 return _liveness_cache[worker_id];
3146 }
3147
3148 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
3149 assert(worker_id < _max_workers, "sanity");
3150 assert(_liveness_cache != NULL, "sanity");
3151 ShenandoahLiveData* ld = _liveness_cache[worker_id];
3152 for (uint i = 0; i < num_regions(); i++) {
3153 ShenandoahLiveData live = ld[i];
3154 if (live > 0) {
3155 ShenandoahHeapRegion* r = get_region(i);
3156 r->increase_live_data_gc_words(live);
3157 ld[i] = 0;
3158 }
3159 }
3160 }