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.hpp"
48 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
49 #include "gc/shenandoah/shenandoahMarkCompact.hpp"
50 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
51 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
52 #include "gc/shenandoah/shenandoahMetrics.hpp"
53 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
54 #include "gc/shenandoah/shenandoahNormalMode.hpp"
55 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
56 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
57 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
58 #include "gc/shenandoah/shenandoahPassiveMode.hpp"
59 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
60 #include "gc/shenandoah/shenandoahStringDedup.hpp"
61 #include "gc/shenandoah/shenandoahTaskqueue.hpp"
62 #include "gc/shenandoah/shenandoahTraversalMode.hpp"
63 #include "gc/shenandoah/shenandoahUtils.hpp"
64 #include "gc/shenandoah/shenandoahVerifier.hpp"
65 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
66 #include "gc/shenandoah/shenandoahVMOperations.hpp"
67 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
68 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
69 #if INCLUDE_JFR
70 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
71 #endif
72
73 #include "memory/metaspace.hpp"
74 #include "oops/compressedOops.inline.hpp"
75 #include "runtime/atomic.hpp"
76 #include "runtime/globals.hpp"
77 #include "runtime/interfaceSupport.inline.hpp"
78 #include "runtime/orderAccess.hpp"
79 #include "runtime/safepointMechanism.hpp"
80 #include "runtime/vmThread.hpp"
81 #include "services/mallocTracker.hpp"
82 #include "utilities/powerOfTwo.hpp"
83
84 #ifdef ASSERT
85 template <class T>
86 void ShenandoahAssertToSpaceClosure::do_oop_work(T* p) {
87 T o = RawAccess<>::oop_load(p);
88 if (! CompressedOops::is_null(o)) {
89 oop obj = CompressedOops::decode_not_null(o);
90 shenandoah_assert_not_forwarded(p, obj);
91 }
92 }
93
94 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_work(p); }
95 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_work(p); }
96 #endif
97
98 class ShenandoahPretouchHeapTask : public AbstractGangTask {
99 private:
100 ShenandoahRegionIterator _regions;
101 const size_t _page_size;
102 public:
103 ShenandoahPretouchHeapTask(size_t page_size) :
104 AbstractGangTask("Shenandoah Pretouch Heap"),
105 _page_size(page_size) {}
106
107 virtual void work(uint worker_id) {
108 ShenandoahHeapRegion* r = _regions.next();
109 while (r != NULL) {
110 os::pretouch_memory(r->bottom(), r->end(), _page_size);
111 r = _regions.next();
112 }
113 }
114 };
115
116 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
117 private:
118 ShenandoahRegionIterator _regions;
119 char* _bitmap_base;
120 const size_t _bitmap_size;
121 const size_t _page_size;
122 public:
123 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
124 AbstractGangTask("Shenandoah Pretouch Bitmap"),
125 _bitmap_base(bitmap_base),
126 _bitmap_size(bitmap_size),
127 _page_size(page_size) {}
128
129 virtual void work(uint worker_id) {
130 ShenandoahHeapRegion* r = _regions.next();
131 while (r != NULL) {
132 size_t start = r->region_number() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
133 size_t end = (r->region_number() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
134 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
135
136 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
137
138 r = _regions.next();
139 }
140 }
141 };
142
143 jint ShenandoahHeap::initialize() {
144 initialize_heuristics();
145
146 //
147 // Figure out heap sizing
148 //
149
150 size_t init_byte_size = InitialHeapSize;
151 size_t min_byte_size = MinHeapSize;
152 size_t max_byte_size = MaxHeapSize;
153 size_t heap_alignment = HeapAlignment;
154
155 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
156
157 if (ShenandoahAlwaysPreTouch) {
158 // Enabled pre-touch means the entire heap is committed right away.
159 init_byte_size = max_byte_size;
160 }
161
162 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
163 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
164
165 _num_regions = ShenandoahHeapRegion::region_count();
166
167 size_t num_committed_regions = init_byte_size / reg_size_bytes;
168 num_committed_regions = MIN2(num_committed_regions, _num_regions);
169 assert(num_committed_regions <= _num_regions, "sanity");
170 _initial_size = num_committed_regions * reg_size_bytes;
171
172 size_t num_min_regions = min_byte_size / reg_size_bytes;
173 num_min_regions = MIN2(num_min_regions, _num_regions);
174 assert(num_min_regions <= _num_regions, "sanity");
175 _minimum_size = num_min_regions * reg_size_bytes;
176
177 _committed = _initial_size;
178
179 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
180 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
181
182 //
183 // Reserve and commit memory for heap
184 //
185
186 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
187 initialize_reserved_region(heap_rs);
188 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
189 _heap_region_special = heap_rs.special();
190
191 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
192 "Misaligned heap: " PTR_FORMAT, p2i(base()));
193
194 #if SHENANDOAH_OPTIMIZED_OBJTASK
195 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
196 // Fail if we ever attempt to address more than we can.
197 if ((uintptr_t)heap_rs.end() >= ObjArrayChunkedTask::max_addressable()) {
198 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
199 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
200 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
201 p2i(heap_rs.base()), p2i(heap_rs.end()), ObjArrayChunkedTask::max_addressable());
202 vm_exit_during_initialization("Fatal Error", buf);
203 }
204 #endif
205
206 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
207 if (!_heap_region_special) {
208 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
209 "Cannot commit heap memory");
210 }
211
212 //
213 // Reserve and commit memory for bitmap(s)
214 //
215
216 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
217 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
218
219 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
220
221 guarantee(bitmap_bytes_per_region != 0,
222 "Bitmap bytes per region should not be zero");
223 guarantee(is_power_of_2(bitmap_bytes_per_region),
224 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
225
226 if (bitmap_page_size > bitmap_bytes_per_region) {
227 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
228 _bitmap_bytes_per_slice = bitmap_page_size;
229 } else {
230 _bitmap_regions_per_slice = 1;
231 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
232 }
233
234 guarantee(_bitmap_regions_per_slice >= 1,
235 "Should have at least one region per slice: " SIZE_FORMAT,
236 _bitmap_regions_per_slice);
237
238 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
239 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
240 _bitmap_bytes_per_slice, bitmap_page_size);
241
242 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
243 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
244 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
245 _bitmap_region_special = bitmap.special();
246
247 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
248 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
249 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
250 if (!_bitmap_region_special) {
251 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
252 "Cannot commit bitmap memory");
253 }
254
255 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
256
257 if (ShenandoahVerify) {
258 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
259 if (!verify_bitmap.special()) {
260 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
261 "Cannot commit verification bitmap memory");
262 }
263 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
264 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
265 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
266 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
267 }
268
269 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
270 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
271 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
272 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
273 _aux_bitmap_region_special = aux_bitmap.special();
274 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
275
276 //
277 // Create regions and region sets
278 //
279
280 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
281 _free_set = new ShenandoahFreeSet(this, _num_regions);
282 _collection_set = new ShenandoahCollectionSet(this, sh_rs.base(), sh_rs.size());
283
284 {
285 ShenandoahHeapLocker locker(lock());
286
287 size_t size_words = ShenandoahHeapRegion::region_size_words();
288
289 for (size_t i = 0; i < _num_regions; i++) {
290 HeapWord* start = (HeapWord*)sh_rs.base() + size_words * i;
291 bool is_committed = i < num_committed_regions;
292 ShenandoahHeapRegion* r = new ShenandoahHeapRegion(this, start, size_words, i, is_committed);
293
294 _marking_context->initialize_top_at_mark_start(r);
295 _regions[i] = r;
296 assert(!collection_set()->is_in(i), "New region should not be in collection set");
297 }
298
299 // Initialize to complete
300 _marking_context->mark_complete();
301
302 _free_set->rebuild();
303 }
304
305 if (ShenandoahAlwaysPreTouch) {
306 assert(!AlwaysPreTouch, "Should have been overridden");
307
308 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
309 // before initialize() below zeroes it with initializing thread. For any given region,
310 // we touch the region and the corresponding bitmaps from the same thread.
311 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
312
313 size_t pretouch_heap_page_size = heap_page_size;
314 size_t pretouch_bitmap_page_size = bitmap_page_size;
315
316 #ifdef LINUX
317 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
318 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
319 // them into huge one. Therefore, we need to pretouch with smaller pages.
320 if (UseTransparentHugePages) {
321 pretouch_heap_page_size = (size_t)os::vm_page_size();
322 pretouch_bitmap_page_size = (size_t)os::vm_page_size();
323 }
324 #endif
325
326 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
327 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
328
329 log_info(gc, init)("Pretouch bitmap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
330 _num_regions, pretouch_bitmap_page_size);
331 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, pretouch_bitmap_page_size);
332 _workers->run_task(&bcl);
333
334 log_info(gc, init)("Pretouch heap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
335 _num_regions, pretouch_heap_page_size);
336 ShenandoahPretouchHeapTask hcl(pretouch_heap_page_size);
337 _workers->run_task(&hcl);
338 }
339
340 //
341 // Initialize the rest of GC subsystems
342 //
343
344 _liveness_cache = NEW_C_HEAP_ARRAY(jushort*, _max_workers, mtGC);
345 for (uint worker = 0; worker < _max_workers; worker++) {
346 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(jushort, _num_regions, mtGC);
347 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(jushort));
348 }
349
350 // There should probably be Shenandoah-specific options for these,
351 // just as there are G1-specific options.
352 {
353 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
354 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
355 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
356 }
357
358 _monitoring_support = new ShenandoahMonitoringSupport(this);
359 _phase_timings = new ShenandoahPhaseTimings();
360 ShenandoahStringDedup::initialize();
361 ShenandoahCodeRoots::initialize();
362
363 if (ShenandoahPacing) {
364 _pacer = new ShenandoahPacer(this);
365 _pacer->setup_for_idle();
366 } else {
367 _pacer = NULL;
368 }
369
370 _traversal_gc = strcmp(ShenandoahGCMode, "traversal") == 0 ?
371 new ShenandoahTraversalGC(this, _num_regions) :
372 NULL;
373
374 _control_thread = new ShenandoahControlThread();
375
376 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max",
377 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size),
378 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size),
379 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity())
380 );
381
382 log_info(gc, init)("Safepointing mechanism: %s",
383 SafepointMechanism::uses_thread_local_poll() ? "thread-local poll" :
384 (SafepointMechanism::uses_global_page_poll() ? "global-page poll" : "unknown"));
385
386 return JNI_OK;
387 }
388
389 void ShenandoahHeap::initialize_heuristics() {
390 if (ShenandoahGCMode != NULL) {
391 if (strcmp(ShenandoahGCMode, "traversal") == 0) {
392 _gc_mode = new ShenandoahTraversalMode();
393 } else if (strcmp(ShenandoahGCMode, "normal") == 0) {
394 _gc_mode = new ShenandoahNormalMode();
395 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
396 _gc_mode = new ShenandoahPassiveMode();
397 } else {
398 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
399 }
400 } else {
401 ShouldNotReachHere();
402 }
403 _gc_mode->initialize_flags();
404 _heuristics = _gc_mode->initialize_heuristics();
405
406 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
407 vm_exit_during_initialization(
408 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
409 _heuristics->name()));
410 }
411 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
412 vm_exit_during_initialization(
413 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
414 _heuristics->name()));
415 }
416 log_info(gc, init)("Shenandoah heuristics: %s",
417 _heuristics->name());
418 }
419
420 #ifdef _MSC_VER
421 #pragma warning( push )
422 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
423 #endif
424
425 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
426 CollectedHeap(),
427 _initial_size(0),
428 _used(0),
429 _committed(0),
430 _bytes_allocated_since_gc_start(0),
431 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
432 _workers(NULL),
433 _safepoint_workers(NULL),
434 _heap_region_special(false),
435 _num_regions(0),
436 _regions(NULL),
437 _update_refs_iterator(this),
438 _control_thread(NULL),
439 _shenandoah_policy(policy),
440 _heuristics(NULL),
441 _free_set(NULL),
442 _scm(new ShenandoahConcurrentMark()),
443 _traversal_gc(NULL),
444 _full_gc(new ShenandoahMarkCompact()),
445 _pacer(NULL),
446 _verifier(NULL),
447 _phase_timings(NULL),
448 _monitoring_support(NULL),
449 _memory_pool(NULL),
450 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
451 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
452 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
453 _soft_ref_policy(),
454 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
455 _ref_processor(NULL),
456 _marking_context(NULL),
457 _bitmap_size(0),
458 _bitmap_regions_per_slice(0),
459 _bitmap_bytes_per_slice(0),
460 _bitmap_region_special(false),
461 _aux_bitmap_region_special(false),
462 _liveness_cache(NULL),
463 _collection_set(NULL)
464 {
465 log_info(gc, init)("GC threads: " UINT32_FORMAT " parallel, " UINT32_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
466 log_info(gc, init)("Reference processing: %s", ParallelRefProcEnabled ? "parallel" : "serial");
467
468 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
469
470 _max_workers = MAX2(_max_workers, 1U);
471 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
472 /* are_GC_task_threads */ true,
473 /* are_ConcurrentGC_threads */ true);
474 if (_workers == NULL) {
475 vm_exit_during_initialization("Failed necessary allocation.");
476 } else {
477 _workers->initialize_workers();
478 }
479
480 if (ParallelGCThreads > 1) {
481 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
482 ParallelGCThreads,
483 /* are_GC_task_threads */ false,
484 /* are_ConcurrentGC_threads */ false);
485 _safepoint_workers->initialize_workers();
486 }
487 }
488
489 #ifdef _MSC_VER
490 #pragma warning( pop )
491 #endif
492
493 class ShenandoahResetBitmapTask : public AbstractGangTask {
494 private:
495 ShenandoahRegionIterator _regions;
496
497 public:
498 ShenandoahResetBitmapTask() :
499 AbstractGangTask("Parallel Reset Bitmap Task") {}
500
501 void work(uint worker_id) {
502 ShenandoahHeapRegion* region = _regions.next();
503 ShenandoahHeap* heap = ShenandoahHeap::heap();
504 ShenandoahMarkingContext* const ctx = heap->marking_context();
505 while (region != NULL) {
506 if (heap->is_bitmap_slice_committed(region)) {
507 ctx->clear_bitmap(region);
508 }
509 region = _regions.next();
510 }
511 }
512 };
513
514 void ShenandoahHeap::reset_mark_bitmap() {
515 assert_gc_workers(_workers->active_workers());
516 mark_incomplete_marking_context();
517
518 ShenandoahResetBitmapTask task;
519 _workers->run_task(&task);
520 }
521
522 void ShenandoahHeap::print_on(outputStream* st) const {
523 st->print_cr("Shenandoah Heap");
524 st->print_cr(" " SIZE_FORMAT "%s total, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
525 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
526 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
527 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
528 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
529 num_regions(),
530 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
531 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
532
533 st->print("Status: ");
534 if (has_forwarded_objects()) st->print("has forwarded objects, ");
535 if (is_concurrent_mark_in_progress()) st->print("marking, ");
536 if (is_evacuation_in_progress()) st->print("evacuating, ");
537 if (is_update_refs_in_progress()) st->print("updating refs, ");
538 if (is_concurrent_traversal_in_progress()) st->print("traversal, ");
539 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
540 if (is_full_gc_in_progress()) st->print("full gc, ");
541 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
542 if (is_concurrent_root_in_progress()) st->print("concurrent roots, ");
543
544 if (cancelled_gc()) {
545 st->print("cancelled");
546 } else {
547 st->print("not cancelled");
548 }
549 st->cr();
550
551 st->print_cr("Reserved region:");
552 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
553 p2i(reserved_region().start()),
554 p2i(reserved_region().end()));
555
556 ShenandoahCollectionSet* cset = collection_set();
557 st->print_cr("Collection set:");
558 if (cset != NULL) {
559 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
560 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
561 } else {
562 st->print_cr(" (NULL)");
563 }
564
565 st->cr();
566 MetaspaceUtils::print_on(st);
567
568 if (Verbose) {
569 print_heap_regions_on(st);
570 }
571 }
572
573 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
574 public:
575 void do_thread(Thread* thread) {
576 assert(thread != NULL, "Sanity");
577 assert(thread->is_Worker_thread(), "Only worker thread expected");
578 ShenandoahThreadLocalData::initialize_gclab(thread);
579 }
580 };
581
582 void ShenandoahHeap::post_initialize() {
583 CollectedHeap::post_initialize();
584 MutexLocker ml(Threads_lock);
585
586 ShenandoahInitWorkerGCLABClosure init_gclabs;
587 _workers->threads_do(&init_gclabs);
588
589 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
590 // Now, we will let WorkGang to initialize gclab when new worker is created.
591 _workers->set_initialize_gclab();
592
593 _scm->initialize(_max_workers);
594 _full_gc->initialize(_gc_timer);
595
596 ref_processing_init();
597
598 _heuristics->initialize();
599
600 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
601 }
602
603 size_t ShenandoahHeap::used() const {
604 return Atomic::load_acquire(&_used);
605 }
606
607 size_t ShenandoahHeap::committed() const {
608 OrderAccess::acquire();
609 return _committed;
610 }
611
612 void ShenandoahHeap::increase_committed(size_t bytes) {
613 assert_heaplock_or_safepoint();
614 _committed += bytes;
615 }
616
617 void ShenandoahHeap::decrease_committed(size_t bytes) {
618 assert_heaplock_or_safepoint();
619 _committed -= bytes;
620 }
621
622 void ShenandoahHeap::increase_used(size_t bytes) {
623 Atomic::add(&_used, bytes);
624 }
625
626 void ShenandoahHeap::set_used(size_t bytes) {
627 Atomic::release_store_fence(&_used, bytes);
628 }
629
630 void ShenandoahHeap::decrease_used(size_t bytes) {
631 assert(used() >= bytes, "never decrease heap size by more than we've left");
632 Atomic::sub(&_used, bytes);
633 }
634
635 void ShenandoahHeap::increase_allocated(size_t bytes) {
636 Atomic::add(&_bytes_allocated_since_gc_start, bytes);
637 }
638
639 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
640 size_t bytes = words * HeapWordSize;
641 if (!waste) {
642 increase_used(bytes);
643 }
644 increase_allocated(bytes);
645 if (ShenandoahPacing) {
646 control_thread()->pacing_notify_alloc(words);
647 if (waste) {
648 pacer()->claim_for_alloc(words, true);
649 }
650 }
651 }
652
653 size_t ShenandoahHeap::capacity() const {
654 return committed();
655 }
656
657 size_t ShenandoahHeap::max_capacity() const {
658 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
659 }
660
661 size_t ShenandoahHeap::min_capacity() const {
662 return _minimum_size;
663 }
664
665 size_t ShenandoahHeap::initial_capacity() const {
666 return _initial_size;
667 }
668
669 bool ShenandoahHeap::is_in(const void* p) const {
670 HeapWord* heap_base = (HeapWord*) base();
671 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
672 return p >= heap_base && p < last_region_end;
673 }
674
675 void ShenandoahHeap::op_uncommit(double shrink_before) {
676 assert (ShenandoahUncommit, "should be enabled");
677
678 // Application allocates from the beginning of the heap, and GC allocates at
679 // the end of it. It is more efficient to uncommit from the end, so that applications
680 // could enjoy the near committed regions. GC allocations are much less frequent,
681 // and therefore can accept the committing costs.
682
683 size_t count = 0;
684 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
685 ShenandoahHeapRegion* r = get_region(i - 1);
686 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
687 ShenandoahHeapLocker locker(lock());
688 if (r->is_empty_committed()) {
689 // Do not uncommit below minimal capacity
690 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
691 break;
692 }
693
694 r->make_uncommitted();
695 count++;
696 }
697 }
698 SpinPause(); // allow allocators to take the lock
699 }
700
701 if (count > 0) {
702 control_thread()->notify_heap_changed();
703 }
704 }
705
706 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
707 // New object should fit the GCLAB size
708 size_t min_size = MAX2(size, PLAB::min_size());
709
710 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
711 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
712 new_size = MIN2(new_size, PLAB::max_size());
713 new_size = MAX2(new_size, PLAB::min_size());
714
715 // Record new heuristic value even if we take any shortcut. This captures
716 // the case when moderately-sized objects always take a shortcut. At some point,
717 // heuristics should catch up with them.
718 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
719
720 if (new_size < size) {
721 // New size still does not fit the object. Fall back to shared allocation.
722 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
723 return NULL;
724 }
725
726 // Retire current GCLAB, and allocate a new one.
727 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
728 gclab->retire();
729
730 size_t actual_size = 0;
731 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
732 if (gclab_buf == NULL) {
733 return NULL;
734 }
735
736 assert (size <= actual_size, "allocation should fit");
737
738 if (ZeroTLAB) {
739 // ..and clear it.
740 Copy::zero_to_words(gclab_buf, actual_size);
741 } else {
742 // ...and zap just allocated object.
743 #ifdef ASSERT
744 // Skip mangling the space corresponding to the object header to
745 // ensure that the returned space is not considered parsable by
746 // any concurrent GC thread.
747 size_t hdr_size = oopDesc::header_size();
748 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
749 #endif // ASSERT
750 }
751 gclab->set_buf(gclab_buf, actual_size);
752 return gclab->allocate(size);
753 }
754
755 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
756 size_t requested_size,
757 size_t* actual_size) {
758 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
759 HeapWord* res = allocate_memory(req);
760 if (res != NULL) {
761 *actual_size = req.actual_size();
762 } else {
763 *actual_size = 0;
764 }
765 return res;
766 }
767
768 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
769 size_t word_size,
770 size_t* actual_size) {
771 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
772 HeapWord* res = allocate_memory(req);
773 if (res != NULL) {
774 *actual_size = req.actual_size();
775 } else {
776 *actual_size = 0;
777 }
778 return res;
779 }
780
781 ShenandoahHeap* ShenandoahHeap::heap() {
782 CollectedHeap* heap = Universe::heap();
783 assert(heap != NULL, "Unitialized access to ShenandoahHeap::heap()");
784 assert(heap->kind() == CollectedHeap::Shenandoah, "not a shenandoah heap");
785 return (ShenandoahHeap*) heap;
786 }
787
788 ShenandoahHeap* ShenandoahHeap::heap_no_check() {
789 CollectedHeap* heap = Universe::heap();
790 return (ShenandoahHeap*) heap;
791 }
792
793 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
794 intptr_t pacer_epoch = 0;
795 bool in_new_region = false;
796 HeapWord* result = NULL;
797
798 if (req.is_mutator_alloc()) {
799 if (ShenandoahPacing) {
800 pacer()->pace_for_alloc(req.size());
801 pacer_epoch = pacer()->epoch();
802 }
803
804 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
805 result = allocate_memory_under_lock(req, in_new_region);
806 }
807
808 // Allocation failed, block until control thread reacted, then retry allocation.
809 //
810 // It might happen that one of the threads requesting allocation would unblock
811 // way later after GC happened, only to fail the second allocation, because
812 // other threads have already depleted the free storage. In this case, a better
813 // strategy is to try again, as long as GC makes progress.
814 //
815 // Then, we need to make sure the allocation was retried after at least one
816 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
817
818 size_t tries = 0;
819
820 while (result == NULL && _progress_last_gc.is_set()) {
821 tries++;
822 control_thread()->handle_alloc_failure(req.size());
823 result = allocate_memory_under_lock(req, in_new_region);
824 }
825
826 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
827 tries++;
828 control_thread()->handle_alloc_failure(req.size());
829 result = allocate_memory_under_lock(req, in_new_region);
830 }
831
832 } else {
833 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
834 result = allocate_memory_under_lock(req, in_new_region);
835 // Do not call handle_alloc_failure() here, because we cannot block.
836 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
837 }
838
839 if (in_new_region) {
840 control_thread()->notify_heap_changed();
841 }
842
843 if (result != NULL) {
844 size_t requested = req.size();
845 size_t actual = req.actual_size();
846
847 assert (req.is_lab_alloc() || (requested == actual),
848 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
849 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
850
851 if (req.is_mutator_alloc()) {
852 notify_mutator_alloc_words(actual, false);
853
854 // If we requested more than we were granted, give the rest back to pacer.
855 // This only matters if we are in the same pacing epoch: do not try to unpace
856 // over the budget for the other phase.
857 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
858 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
859 }
860 } else {
861 increase_used(actual*HeapWordSize);
862 }
863 }
864
865 return result;
866 }
867
868 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
869 ShenandoahHeapLocker locker(lock());
870 return _free_set->allocate(req, in_new_region);
871 }
872
873 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
874 bool* gc_overhead_limit_was_exceeded) {
875 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
876 return allocate_memory(req);
877 }
878
879 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
880 size_t size,
881 Metaspace::MetadataType mdtype) {
882 MetaWord* result;
883
884 // Inform metaspace OOM to GC heuristics if class unloading is possible.
885 if (heuristics()->can_unload_classes()) {
886 ShenandoahHeuristics* h = heuristics();
887 h->record_metaspace_oom();
888 }
889
890 // Expand and retry allocation
891 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
892 if (result != NULL) {
893 return result;
894 }
895
896 // Start full GC
897 collect(GCCause::_metadata_GC_clear_soft_refs);
898
899 // Retry allocation
900 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
901 if (result != NULL) {
902 return result;
903 }
904
905 // Expand and retry allocation
906 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
907 if (result != NULL) {
908 return result;
909 }
910
911 // Out of memory
912 return NULL;
913 }
914
915 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
916 private:
917 ShenandoahHeap* const _heap;
918 Thread* const _thread;
919 public:
920 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
921 _heap(heap), _thread(Thread::current()) {}
922
923 void do_object(oop p) {
924 shenandoah_assert_marked(NULL, p);
925 if (!p->is_forwarded()) {
926 _heap->evacuate_object(p, _thread);
927 }
928 }
929 };
930
931 class ShenandoahEvacuationTask : public AbstractGangTask {
932 private:
933 ShenandoahHeap* const _sh;
934 ShenandoahCollectionSet* const _cs;
935 bool _concurrent;
936 public:
937 ShenandoahEvacuationTask(ShenandoahHeap* sh,
938 ShenandoahCollectionSet* cs,
939 bool concurrent) :
940 AbstractGangTask("Parallel Evacuation Task"),
941 _sh(sh),
942 _cs(cs),
943 _concurrent(concurrent)
944 {}
945
946 void work(uint worker_id) {
947 if (_concurrent) {
948 ShenandoahConcurrentWorkerSession worker_session(worker_id);
949 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
950 ShenandoahEvacOOMScope oom_evac_scope;
951 do_work();
952 } else {
953 ShenandoahParallelWorkerSession worker_session(worker_id);
954 ShenandoahEvacOOMScope oom_evac_scope;
955 do_work();
956 }
957 }
958
959 private:
960 void do_work() {
961 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
962 ShenandoahHeapRegion* r;
963 while ((r =_cs->claim_next()) != NULL) {
964 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->region_number());
965 _sh->marked_object_iterate(r, &cl);
966
967 if (ShenandoahPacing) {
968 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
969 }
970
971 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
972 break;
973 }
974 }
975 }
976 };
977
978 void ShenandoahHeap::trash_cset_regions() {
979 ShenandoahHeapLocker locker(lock());
980
981 ShenandoahCollectionSet* set = collection_set();
982 ShenandoahHeapRegion* r;
983 set->clear_current_index();
984 while ((r = set->next()) != NULL) {
985 r->make_trash();
986 }
987 collection_set()->clear();
988 }
989
990 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
991 st->print_cr("Heap Regions:");
992 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
993 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
994 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start (previous, next)");
995 st->print_cr("SN=alloc sequence numbers (first mutator, last mutator, first gc, last gc)");
996
997 for (size_t i = 0; i < num_regions(); i++) {
998 get_region(i)->print_on(st);
999 }
1000 }
1001
1002 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1003 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1004
1005 oop humongous_obj = oop(start->bottom());
1006 size_t size = humongous_obj->size();
1007 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1008 size_t index = start->region_number() + required_regions - 1;
1009
1010 assert(!start->has_live(), "liveness must be zero");
1011
1012 for(size_t i = 0; i < required_regions; i++) {
1013 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1014 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1015 ShenandoahHeapRegion* region = get_region(index --);
1016
1017 assert(region->is_humongous(), "expect correct humongous start or continuation");
1018 assert(!region->is_cset(), "Humongous region should not be in collection set");
1019
1020 region->make_trash_immediate();
1021 }
1022 }
1023
1024 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1025 public:
1026 void do_thread(Thread* thread) {
1027 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1028 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1029 gclab->retire();
1030 }
1031 };
1032
1033 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
1034 if (UseTLAB) {
1035 CollectedHeap::ensure_parsability(retire_tlabs);
1036 }
1037 ShenandoahRetireGCLABClosure cl;
1038 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1039 cl.do_thread(t);
1040 }
1041 workers()->threads_do(&cl);
1042 }
1043
1044 void ShenandoahHeap::resize_tlabs() {
1045 CollectedHeap::resize_all_tlabs();
1046 }
1047
1048 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1049 private:
1050 ShenandoahRootEvacuator* _rp;
1051
1052 public:
1053 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1054 AbstractGangTask("Shenandoah evacuate and update roots"),
1055 _rp(rp) {}
1056
1057 void work(uint worker_id) {
1058 ShenandoahParallelWorkerSession worker_session(worker_id);
1059 ShenandoahEvacOOMScope oom_evac_scope;
1060 ShenandoahEvacuateUpdateRootsClosure<> cl;
1061 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1062 _rp->roots_do(worker_id, &cl);
1063 }
1064 };
1065
1066 void ShenandoahHeap::evacuate_and_update_roots() {
1067 #if COMPILER2_OR_JVMCI
1068 DerivedPointerTable::clear();
1069 #endif
1070 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1071 {
1072 // Include concurrent roots if current cycle can not process those roots concurrently
1073 ShenandoahRootEvacuator rp(workers()->active_workers(),
1074 ShenandoahPhaseTimings::init_evac,
1075 !ShenandoahConcurrentRoots::should_do_concurrent_roots(),
1076 !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
1077 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1078 workers()->run_task(&roots_task);
1079 }
1080
1081 #if COMPILER2_OR_JVMCI
1082 DerivedPointerTable::update_pointers();
1083 #endif
1084 }
1085
1086 // Returns size in bytes
1087 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1088 if (ShenandoahElasticTLAB) {
1089 // With Elastic TLABs, return the max allowed size, and let the allocation path
1090 // figure out the safe size for current allocation.
1091 return ShenandoahHeapRegion::max_tlab_size_bytes();
1092 } else {
1093 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1094 }
1095 }
1096
1097 size_t ShenandoahHeap::max_tlab_size() const {
1098 // Returns size in words
1099 return ShenandoahHeapRegion::max_tlab_size_words();
1100 }
1101
1102 class ShenandoahRetireAndResetGCLABClosure : public ThreadClosure {
1103 public:
1104 void do_thread(Thread* thread) {
1105 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1106 gclab->retire();
1107 if (ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1108 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1109 }
1110 }
1111 };
1112
1113 void ShenandoahHeap::retire_and_reset_gclabs() {
1114 ShenandoahRetireAndResetGCLABClosure cl;
1115 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1116 cl.do_thread(t);
1117 }
1118 workers()->threads_do(&cl);
1119 }
1120
1121 void ShenandoahHeap::collect(GCCause::Cause cause) {
1122 control_thread()->request_gc(cause);
1123 }
1124
1125 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1126 //assert(false, "Shouldn't need to do full collections");
1127 }
1128
1129 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1130 Space* sp = heap_region_containing(addr);
1131 if (sp != NULL) {
1132 return sp->block_start(addr);
1133 }
1134 return NULL;
1135 }
1136
1137 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1138 Space* sp = heap_region_containing(addr);
1139 return sp->block_is_obj(addr);
1140 }
1141
1142 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1143 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1144 }
1145
1146 jlong ShenandoahHeap::millis_since_last_gc() {
1147 double v = heuristics()->time_since_last_gc() * 1000;
1148 assert(0 <= v && v <= max_jlong, "value should fit: %f", v);
1149 return (jlong)v;
1150 }
1151
1152 void ShenandoahHeap::prepare_for_verify() {
1153 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1154 make_parsable(false);
1155 }
1156 }
1157
1158 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1159 workers()->print_worker_threads_on(st);
1160 if (ShenandoahStringDedup::is_enabled()) {
1161 ShenandoahStringDedup::print_worker_threads_on(st);
1162 }
1163 }
1164
1165 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1166 workers()->threads_do(tcl);
1167 if (_safepoint_workers != NULL) {
1168 _safepoint_workers->threads_do(tcl);
1169 }
1170 if (ShenandoahStringDedup::is_enabled()) {
1171 ShenandoahStringDedup::threads_do(tcl);
1172 }
1173 }
1174
1175 void ShenandoahHeap::print_tracing_info() const {
1176 LogTarget(Info, gc, stats) lt;
1177 if (lt.is_enabled()) {
1178 ResourceMark rm;
1179 LogStream ls(lt);
1180
1181 phase_timings()->print_on(&ls);
1182
1183 ls.cr();
1184 ls.cr();
1185
1186 shenandoah_policy()->print_gc_stats(&ls);
1187
1188 ls.cr();
1189 ls.cr();
1190
1191 if (ShenandoahPacing) {
1192 pacer()->print_on(&ls);
1193 }
1194
1195 ls.cr();
1196 ls.cr();
1197 }
1198 }
1199
1200 void ShenandoahHeap::verify(VerifyOption vo) {
1201 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1202 if (ShenandoahVerify) {
1203 verifier()->verify_generic(vo);
1204 } else {
1205 // TODO: Consider allocating verification bitmaps on demand,
1206 // and turn this on unconditionally.
1207 }
1208 }
1209 }
1210 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1211 return _free_set->capacity();
1212 }
1213
1214 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1215 private:
1216 MarkBitMap* _bitmap;
1217 Stack<oop,mtGC>* _oop_stack;
1218 ShenandoahHeap* const _heap;
1219 ShenandoahMarkingContext* const _marking_context;
1220
1221 template <class T>
1222 void do_oop_work(T* p) {
1223 T o = RawAccess<>::oop_load(p);
1224 if (!CompressedOops::is_null(o)) {
1225 oop obj = CompressedOops::decode_not_null(o);
1226 if (_heap->is_concurrent_root_in_progress() && !_marking_context->is_marked(obj)) {
1227 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1228 return;
1229 }
1230 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1231
1232 assert(oopDesc::is_oop(obj), "must be a valid oop");
1233 if (!_bitmap->is_marked(obj)) {
1234 _bitmap->mark(obj);
1235 _oop_stack->push(obj);
1236 }
1237 }
1238 }
1239 public:
1240 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1241 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1242 _marking_context(_heap->marking_context()) {}
1243 void do_oop(oop* p) { do_oop_work(p); }
1244 void do_oop(narrowOop* p) { do_oop_work(p); }
1245 };
1246
1247 /*
1248 * This is public API, used in preparation of object_iterate().
1249 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1250 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1251 * control, we call SH::make_tlabs_parsable().
1252 */
1253 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1254 // No-op.
1255 }
1256
1257 /*
1258 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1259 *
1260 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1261 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1262 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1263 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1264 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1265 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1266 * wiped the bitmap in preparation for next marking).
1267 *
1268 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1269 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1270 * is allowed to report dead objects, but is not required to do so.
1271 */
1272 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1273 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1274 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1275 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1276 return;
1277 }
1278
1279 // Reset bitmap
1280 _aux_bit_map.clear();
1281
1282 Stack<oop,mtGC> oop_stack;
1283
1284 // First, we process GC roots according to current GC cycle. This populates the work stack with initial objects.
1285 ShenandoahHeapIterationRootScanner rp;
1286 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1287
1288 rp.roots_do(&oops);
1289
1290 // Work through the oop stack to traverse heap.
1291 while (! oop_stack.is_empty()) {
1292 oop obj = oop_stack.pop();
1293 assert(oopDesc::is_oop(obj), "must be a valid oop");
1294 cl->do_object(obj);
1295 obj->oop_iterate(&oops);
1296 }
1297
1298 assert(oop_stack.is_empty(), "should be empty");
1299
1300 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1301 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1302 }
1303 }
1304
1305 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1306 void ShenandoahHeap::keep_alive(oop obj) {
1307 if (is_concurrent_mark_in_progress()) {
1308 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1309 }
1310 }
1311
1312 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1313 for (size_t i = 0; i < num_regions(); i++) {
1314 ShenandoahHeapRegion* current = get_region(i);
1315 blk->heap_region_do(current);
1316 }
1317 }
1318
1319 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1320 private:
1321 ShenandoahHeap* const _heap;
1322 ShenandoahHeapRegionClosure* const _blk;
1323
1324 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));
1325 volatile size_t _index;
1326 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
1327
1328 public:
1329 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1330 AbstractGangTask("Parallel Region Task"),
1331 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1332
1333 void work(uint worker_id) {
1334 size_t stride = ShenandoahParallelRegionStride;
1335
1336 size_t max = _heap->num_regions();
1337 while (_index < max) {
1338 size_t cur = Atomic::fetch_and_add(&_index, stride);
1339 size_t start = cur;
1340 size_t end = MIN2(cur + stride, max);
1341 if (start >= max) break;
1342
1343 for (size_t i = cur; i < end; i++) {
1344 ShenandoahHeapRegion* current = _heap->get_region(i);
1345 _blk->heap_region_do(current);
1346 }
1347 }
1348 }
1349 };
1350
1351 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1352 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1353 if (num_regions() > ShenandoahParallelRegionStride) {
1354 ShenandoahParallelHeapRegionTask task(blk);
1355 workers()->run_task(&task);
1356 } else {
1357 heap_region_iterate(blk);
1358 }
1359 }
1360
1361 class ShenandoahClearLivenessClosure : public ShenandoahHeapRegionClosure {
1362 private:
1363 ShenandoahMarkingContext* const _ctx;
1364 public:
1365 ShenandoahClearLivenessClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1366
1367 void heap_region_do(ShenandoahHeapRegion* r) {
1368 if (r->is_active()) {
1369 r->clear_live_data();
1370 _ctx->capture_top_at_mark_start(r);
1371 } else {
1372 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1373 assert(_ctx->top_at_mark_start(r) == r->top(),
1374 "Region " SIZE_FORMAT " should already have correct TAMS", r->region_number());
1375 }
1376 }
1377
1378 bool is_thread_safe() { return true; }
1379 };
1380
1381 void ShenandoahHeap::op_init_mark() {
1382 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1383 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1384
1385 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1386 assert(!marking_context()->is_complete(), "should not be complete");
1387 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1388
1389 if (ShenandoahVerify) {
1390 verifier()->verify_before_concmark();
1391 }
1392
1393 if (VerifyBeforeGC) {
1394 Universe::verify();
1395 }
1396
1397 set_concurrent_mark_in_progress(true);
1398 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1399 {
1400 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1401 make_parsable(true);
1402 }
1403
1404 {
1405 ShenandoahGCPhase phase(ShenandoahPhaseTimings::clear_liveness);
1406 ShenandoahClearLivenessClosure clc;
1407 parallel_heap_region_iterate(&clc);
1408 }
1409
1410 // Make above changes visible to worker threads
1411 OrderAccess::fence();
1412
1413 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1414
1415 if (UseTLAB) {
1416 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1417 resize_tlabs();
1418 }
1419
1420 if (ShenandoahPacing) {
1421 pacer()->setup_for_mark();
1422 }
1423 }
1424
1425 void ShenandoahHeap::op_mark() {
1426 concurrent_mark()->mark_from_roots();
1427 }
1428
1429 class ShenandoahCompleteLivenessClosure : public ShenandoahHeapRegionClosure {
1430 private:
1431 ShenandoahMarkingContext* const _ctx;
1432 public:
1433 ShenandoahCompleteLivenessClosure() : _ctx(ShenandoahHeap::heap()->complete_marking_context()) {}
1434
1435 void heap_region_do(ShenandoahHeapRegion* r) {
1436 if (r->is_active()) {
1437 HeapWord *tams = _ctx->top_at_mark_start(r);
1438 HeapWord *top = r->top();
1439 if (top > tams) {
1440 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1441 }
1442 } else {
1443 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1444 assert(_ctx->top_at_mark_start(r) == r->top(),
1445 "Region " SIZE_FORMAT " should have correct TAMS", r->region_number());
1446 }
1447 }
1448
1449 bool is_thread_safe() { return true; }
1450 };
1451
1452 void ShenandoahHeap::op_final_mark() {
1453 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1454 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1455
1456 // It is critical that we
1457 // evacuate roots right after finishing marking, so that we don't
1458 // get unmarked objects in the roots.
1459
1460 if (!cancelled_gc()) {
1461 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1462
1463 // Marking is completed, deactivate SATB barrier
1464 set_concurrent_mark_in_progress(false);
1465 mark_complete_marking_context();
1466
1467 parallel_cleaning(false /* full gc*/);
1468
1469 if (ShenandoahVerify) {
1470 verifier()->verify_roots_no_forwarded();
1471 }
1472 // All allocations past TAMS are implicitly live, adjust the region data.
1473 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1474 {
1475 ShenandoahGCPhase phase(ShenandoahPhaseTimings::complete_liveness);
1476 ShenandoahCompleteLivenessClosure cl;
1477 parallel_heap_region_iterate(&cl);
1478 }
1479
1480 // Force the threads to reacquire their TLABs outside the collection set.
1481 {
1482 ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs);
1483 make_parsable(true);
1484 }
1485
1486 // We are about to select the collection set, make sure it knows about
1487 // current pinning status. Also, this allows trashing more regions that
1488 // now have their pinning status dropped.
1489 {
1490 ShenandoahGCPhase phase(ShenandoahPhaseTimings::sync_pinned);
1491 sync_pinned_region_status();
1492 }
1493
1494 // Trash the collection set left over from previous cycle, if any.
1495 {
1496 ShenandoahGCPhase phase(ShenandoahPhaseTimings::trash_cset);
1497 trash_cset_regions();
1498 }
1499
1500 {
1501 ShenandoahGCPhase phase(ShenandoahPhaseTimings::prepare_evac);
1502
1503 ShenandoahHeapLocker locker(lock());
1504 _collection_set->clear();
1505 _free_set->clear();
1506
1507 heuristics()->choose_collection_set(_collection_set);
1508
1509 _free_set->rebuild();
1510 }
1511
1512 if (!is_degenerated_gc_in_progress()) {
1513 prepare_concurrent_roots();
1514 prepare_concurrent_unloading();
1515 }
1516
1517 // If collection set has candidates, start evacuation.
1518 // Otherwise, bypass the rest of the cycle.
1519 if (!collection_set()->is_empty()) {
1520 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1521
1522 if (ShenandoahVerify) {
1523 verifier()->verify_before_evacuation();
1524 }
1525
1526 // Remember limit for updating refs. It's guaranteed that we get no from-space-refs written
1527 // from here on.
1528 for (uint i = 0; i < num_regions(); i++) {
1529 ShenandoahHeapRegion* r = get_region(i);
1530 r->set_update_watermark(r->top());
1531 }
1532
1533 set_evacuation_in_progress(true);
1534 // From here on, we need to update references.
1535 set_has_forwarded_objects(true);
1536
1537 if (!is_degenerated_gc_in_progress()) {
1538 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1539 ShenandoahCodeRoots::arm_nmethods();
1540 }
1541 evacuate_and_update_roots();
1542 }
1543
1544 if (ShenandoahPacing) {
1545 pacer()->setup_for_evac();
1546 }
1547
1548 if (ShenandoahVerify) {
1549 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::None;
1550 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1551 types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots);
1552 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots);
1553 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::StringDedupRoots);
1554 }
1555
1556 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1557 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CodeRoots);
1558 }
1559 verifier()->verify_roots_no_forwarded_except(types);
1560 verifier()->verify_during_evacuation();
1561 }
1562 } else {
1563 if (ShenandoahVerify) {
1564 verifier()->verify_after_concmark();
1565 }
1566
1567 if (VerifyAfterGC) {
1568 Universe::verify();
1569 }
1570 }
1571
1572 } else {
1573 // If this cycle was updating references, we need to keep the has_forwarded_objects
1574 // flag on, for subsequent phases to deal with it.
1575 concurrent_mark()->cancel();
1576 set_concurrent_mark_in_progress(false);
1577
1578 if (process_references()) {
1579 // Abandon reference processing right away: pre-cleaning must have failed.
1580 ReferenceProcessor *rp = ref_processor();
1581 rp->disable_discovery();
1582 rp->abandon_partial_discovery();
1583 rp->verify_no_references_recorded();
1584 }
1585 }
1586 }
1587
1588 void ShenandoahHeap::op_conc_evac() {
1589 ShenandoahEvacuationTask task(this, _collection_set, true);
1590 workers()->run_task(&task);
1591 }
1592
1593 void ShenandoahHeap::op_stw_evac() {
1594 ShenandoahEvacuationTask task(this, _collection_set, false);
1595 workers()->run_task(&task);
1596 }
1597
1598 void ShenandoahHeap::op_updaterefs() {
1599 update_heap_references(true);
1600 }
1601
1602 void ShenandoahHeap::op_cleanup() {
1603 free_set()->recycle_trash();
1604 }
1605
1606 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask {
1607 private:
1608 ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
1609 ShenandoahWeakRoots<true /*concurrent*/> _weak_roots;
1610 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots;
1611 ShenandoahConcurrentStringDedupRoots _dedup_roots;
1612 bool _include_weak_roots;
1613
1614 public:
1615 ShenandoahConcurrentRootsEvacUpdateTask(bool include_weak_roots) :
1616 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Roots Task"),
1617 _include_weak_roots(include_weak_roots) {
1618 }
1619
1620 void work(uint worker_id) {
1621 ShenandoahEvacOOMScope oom;
1622 {
1623 // vm_roots and weak_roots are OopStorage backed roots, concurrent iteration
1624 // may race against OopStorage::release() calls.
1625 ShenandoahEvacUpdateOopStorageRootsClosure cl;
1626 _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1627
1628 if (_include_weak_roots) {
1629 _weak_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1630 }
1631 }
1632
1633 {
1634 ShenandoahEvacuateUpdateRootsClosure<> cl;
1635 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1636 _cld_roots.cld_do(&clds);
1637 }
1638
1639 {
1640 ShenandoahForwardedIsAliveClosure is_alive;
1641 ShenandoahEvacuateUpdateRootsClosure<MO_RELEASE> keep_alive;
1642 _dedup_roots.oops_do(&is_alive, &keep_alive, worker_id);
1643 }
1644 }
1645 };
1646
1647 class ShenandoahEvacUpdateCleanupOopStorageRootsClosure : public BasicOopIterateClosure {
1648 private:
1649 ShenandoahHeap* const _heap;
1650 ShenandoahMarkingContext* const _mark_context;
1651 bool _evac_in_progress;
1652 Thread* const _thread;
1653 size_t _dead_counter;
1654
1655 public:
1656 ShenandoahEvacUpdateCleanupOopStorageRootsClosure();
1657 void do_oop(oop* p);
1658 void do_oop(narrowOop* p);
1659
1660 size_t dead_counter() const;
1661 void reset_dead_counter();
1662 };
1663
1664 ShenandoahEvacUpdateCleanupOopStorageRootsClosure::ShenandoahEvacUpdateCleanupOopStorageRootsClosure() :
1665 _heap(ShenandoahHeap::heap()),
1666 _mark_context(ShenandoahHeap::heap()->marking_context()),
1667 _evac_in_progress(ShenandoahHeap::heap()->is_evacuation_in_progress()),
1668 _thread(Thread::current()),
1669 _dead_counter(0) {
1670 }
1671
1672 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(oop* p) {
1673 const oop obj = RawAccess<>::oop_load(p);
1674 if (!CompressedOops::is_null(obj)) {
1675 if (!_mark_context->is_marked(obj)) {
1676 shenandoah_assert_correct(p, obj);
1677 oop old = Atomic::cmpxchg(p, obj, oop(NULL));
1678 if (obj == old) {
1679 _dead_counter ++;
1680 }
1681 } else if (_evac_in_progress && _heap->in_collection_set(obj)) {
1682 oop resolved = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1683 if (resolved == obj) {
1684 resolved = _heap->evacuate_object(obj, _thread);
1685 }
1686 Atomic::cmpxchg(p, obj, resolved);
1687 assert(_heap->cancelled_gc() ||
1688 _mark_context->is_marked(resolved) && !_heap->in_collection_set(resolved),
1689 "Sanity");
1690 }
1691 }
1692 }
1693
1694 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(narrowOop* p) {
1695 ShouldNotReachHere();
1696 }
1697
1698 size_t ShenandoahEvacUpdateCleanupOopStorageRootsClosure::dead_counter() const {
1699 return _dead_counter;
1700 }
1701
1702 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::reset_dead_counter() {
1703 _dead_counter = 0;
1704 }
1705
1706 // This task not only evacuates/updates marked weak roots, but also "NULL"
1707 // dead weak roots.
1708 class ShenandoahConcurrentWeakRootsEvacUpdateTask : public AbstractGangTask {
1709 private:
1710 ShenandoahWeakRoot<true /*concurrent*/> _jni_roots;
1711 ShenandoahWeakRoot<true /*concurrent*/> _string_table_roots;
1712 ShenandoahWeakRoot<true /*concurrent*/> _resolved_method_table_roots;
1713 ShenandoahWeakRoot<true /*concurrent*/> _vm_roots;
1714
1715 public:
1716 ShenandoahConcurrentWeakRootsEvacUpdateTask() :
1717 AbstractGangTask("Shenandoah Concurrent Weak Root Task"),
1718 _jni_roots(OopStorageSet::jni_weak(), ShenandoahPhaseTimings::JNIWeakRoots),
1719 _string_table_roots(OopStorageSet::string_table_weak(), ShenandoahPhaseTimings::StringTableRoots),
1720 _resolved_method_table_roots(OopStorageSet::resolved_method_table_weak(), ShenandoahPhaseTimings::ResolvedMethodTableRoots),
1721 _vm_roots(OopStorageSet::vm_weak(), ShenandoahPhaseTimings::VMWeakRoots) {
1722 StringTable::reset_dead_counter();
1723 ResolvedMethodTable::reset_dead_counter();
1724 }
1725
1726 ~ShenandoahConcurrentWeakRootsEvacUpdateTask() {
1727 StringTable::finish_dead_counter();
1728 ResolvedMethodTable::finish_dead_counter();
1729 }
1730
1731 void work(uint worker_id) {
1732 ShenandoahEvacOOMScope oom;
1733 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
1734 // may race against OopStorage::release() calls.
1735 ShenandoahEvacUpdateCleanupOopStorageRootsClosure cl;
1736 _jni_roots.oops_do(&cl, worker_id);
1737 _vm_roots.oops_do(&cl, worker_id);
1738
1739 cl.reset_dead_counter();
1740 _string_table_roots.oops_do(&cl, worker_id);
1741 StringTable::inc_dead_counter(cl.dead_counter());
1742
1743 cl.reset_dead_counter();
1744 _resolved_method_table_roots.oops_do(&cl, worker_id);
1745 ResolvedMethodTable::inc_dead_counter(cl.dead_counter());
1746 }
1747 };
1748
1749 void ShenandoahHeap::op_roots() {
1750 if (is_concurrent_root_in_progress()) {
1751 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1752 // Concurrent weak root processing
1753 ShenandoahConcurrentWeakRootsEvacUpdateTask task;
1754 workers()->run_task(&task);
1755
1756 _unloader.unload();
1757 }
1758
1759 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1760 ShenandoahConcurrentRootsEvacUpdateTask task(!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
1761 workers()->run_task(&task);
1762 }
1763 }
1764
1765 set_concurrent_root_in_progress(false);
1766 }
1767
1768 void ShenandoahHeap::op_reset() {
1769 if (ShenandoahPacing) {
1770 pacer()->setup_for_reset();
1771 }
1772 reset_mark_bitmap();
1773 }
1774
1775 void ShenandoahHeap::op_preclean() {
1776 if (ShenandoahPacing) {
1777 pacer()->setup_for_preclean();
1778 }
1779 concurrent_mark()->preclean_weak_refs();
1780 }
1781
1782 void ShenandoahHeap::op_init_traversal() {
1783 traversal_gc()->init_traversal_collection();
1784 }
1785
1786 void ShenandoahHeap::op_traversal() {
1787 traversal_gc()->concurrent_traversal_collection();
1788 }
1789
1790 void ShenandoahHeap::op_final_traversal() {
1791 traversal_gc()->final_traversal_collection();
1792 }
1793
1794 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1795 ShenandoahMetricsSnapshot metrics;
1796 metrics.snap_before();
1797
1798 full_gc()->do_it(cause);
1799 if (UseTLAB) {
1800 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs);
1801 resize_all_tlabs();
1802 }
1803
1804 metrics.snap_after();
1805
1806 if (metrics.is_good_progress()) {
1807 _progress_last_gc.set();
1808 } else {
1809 // Nothing to do. Tell the allocation path that we have failed to make
1810 // progress, and it can finally fail.
1811 _progress_last_gc.unset();
1812 }
1813 }
1814
1815 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1816 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1817 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1818 // some phase, we have to upgrade the Degenerate GC to Full GC.
1819
1820 clear_cancelled_gc();
1821
1822 ShenandoahMetricsSnapshot metrics;
1823 metrics.snap_before();
1824
1825 switch (point) {
1826 case _degenerated_traversal:
1827 {
1828 // Drop the collection set. Note: this leaves some already forwarded objects
1829 // behind, which may be problematic, see comments for ShenandoahEvacAssist
1830 // workarounds in ShenandoahTraversalHeuristics.
1831
1832 ShenandoahHeapLocker locker(lock());
1833 collection_set()->clear_current_index();
1834 for (size_t i = 0; i < collection_set()->count(); i++) {
1835 ShenandoahHeapRegion* r = collection_set()->next();
1836 r->make_regular_bypass();
1837 }
1838 collection_set()->clear();
1839 }
1840 op_final_traversal();
1841 op_cleanup();
1842 return;
1843
1844 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1845 // but enters it at different points, depending on which concurrent phase had
1846 // degenerated.
1847
1848 case _degenerated_outside_cycle:
1849 // We have degenerated from outside the cycle, which means something is bad with
1850 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1851 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1852 // we can do the most aggressive degen cycle, which includes processing references and
1853 // class unloading, unless those features are explicitly disabled.
1854 //
1855 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1856 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1857 set_process_references(heuristics()->can_process_references());
1858 set_unload_classes(heuristics()->can_unload_classes());
1859
1860 if (is_traversal_mode()) {
1861 // Not possible to degenerate from here, upgrade to Full GC right away.
1862 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1863 op_degenerated_fail();
1864 return;
1865 }
1866
1867 op_reset();
1868
1869 op_init_mark();
1870 if (cancelled_gc()) {
1871 op_degenerated_fail();
1872 return;
1873 }
1874
1875 case _degenerated_mark:
1876 op_final_mark();
1877 if (cancelled_gc()) {
1878 op_degenerated_fail();
1879 return;
1880 }
1881
1882 op_cleanup();
1883
1884 case _degenerated_evac:
1885 // If heuristics thinks we should do the cycle, this flag would be set,
1886 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
1887 if (is_evacuation_in_progress()) {
1888
1889 // Degeneration under oom-evac protocol might have left some objects in
1890 // collection set un-evacuated. Restart evacuation from the beginning to
1891 // capture all objects. For all the objects that are already evacuated,
1892 // it would be a simple check, which is supposed to be fast. This is also
1893 // safe to do even without degeneration, as CSet iterator is at beginning
1894 // in preparation for evacuation anyway.
1895 //
1896 // Before doing that, we need to make sure we never had any cset-pinned
1897 // regions. This may happen if allocation failure happened when evacuating
1898 // the about-to-be-pinned object, oom-evac protocol left the object in
1899 // the collection set, and then the pin reached the cset region. If we continue
1900 // the cycle here, we would trash the cset and alive objects in it. To avoid
1901 // it, we fail degeneration right away and slide into Full GC to recover.
1902
1903 {
1904 sync_pinned_region_status();
1905 collection_set()->clear_current_index();
1906
1907 ShenandoahHeapRegion* r;
1908 while ((r = collection_set()->next()) != NULL) {
1909 if (r->is_pinned()) {
1910 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1911 op_degenerated_fail();
1912 return;
1913 }
1914 }
1915
1916 collection_set()->clear_current_index();
1917 }
1918
1919 op_stw_evac();
1920 if (cancelled_gc()) {
1921 op_degenerated_fail();
1922 return;
1923 }
1924 }
1925
1926 // If heuristics thinks we should do the cycle, this flag would be set,
1927 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
1928 if (has_forwarded_objects()) {
1929 op_init_updaterefs();
1930 if (cancelled_gc()) {
1931 op_degenerated_fail();
1932 return;
1933 }
1934 }
1935
1936 case _degenerated_updaterefs:
1937 if (has_forwarded_objects()) {
1938 op_final_updaterefs();
1939 if (cancelled_gc()) {
1940 op_degenerated_fail();
1941 return;
1942 }
1943 }
1944
1945 op_cleanup();
1946 break;
1947
1948 default:
1949 ShouldNotReachHere();
1950 }
1951
1952 if (ShenandoahVerify) {
1953 verifier()->verify_after_degenerated();
1954 }
1955
1956 if (VerifyAfterGC) {
1957 Universe::verify();
1958 }
1959
1960 metrics.snap_after();
1961
1962 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
1963 // because that probably means the heap is overloaded and/or fragmented.
1964 if (!metrics.is_good_progress()) {
1965 _progress_last_gc.unset();
1966 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1967 op_degenerated_futile();
1968 } else {
1969 _progress_last_gc.set();
1970 }
1971 }
1972
1973 void ShenandoahHeap::op_degenerated_fail() {
1974 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
1975 shenandoah_policy()->record_degenerated_upgrade_to_full();
1976 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1977 }
1978
1979 void ShenandoahHeap::op_degenerated_futile() {
1980 shenandoah_policy()->record_degenerated_upgrade_to_full();
1981 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1982 }
1983
1984 void ShenandoahHeap::force_satb_flush_all_threads() {
1985 if (!is_concurrent_mark_in_progress() && !is_concurrent_traversal_in_progress()) {
1986 // No need to flush SATBs
1987 return;
1988 }
1989
1990 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1991 ShenandoahThreadLocalData::set_force_satb_flush(t, true);
1992 }
1993 // The threads are not "acquiring" their thread-local data, but it does not
1994 // hurt to "release" the updates here anyway.
1995 OrderAccess::fence();
1996 }
1997
1998 void ShenandoahHeap::set_gc_state_all_threads(char state) {
1999 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2000 ShenandoahThreadLocalData::set_gc_state(t, state);
2001 }
2002 }
2003
2004 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
2005 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
2006 _gc_state.set_cond(mask, value);
2007 set_gc_state_all_threads(_gc_state.raw_value());
2008 }
2009
2010 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
2011 if (has_forwarded_objects()) {
2012 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
2013 } else {
2014 set_gc_state_mask(MARKING, in_progress);
2015 }
2016 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
2017 }
2018
2019 void ShenandoahHeap::set_concurrent_traversal_in_progress(bool in_progress) {
2020 set_gc_state_mask(TRAVERSAL, in_progress);
2021 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
2022 }
2023
2024 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
2025 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
2026 set_gc_state_mask(EVACUATION, in_progress);
2027 }
2028
2029 void ShenandoahHeap::set_concurrent_root_in_progress(bool in_progress) {
2030 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
2031 if (in_progress) {
2032 _concurrent_root_in_progress.set();
2033 } else {
2034 _concurrent_root_in_progress.unset();
2035 }
2036 }
2037
2038 void ShenandoahHeap::ref_processing_init() {
2039 assert(_max_workers > 0, "Sanity");
2040
2041 _ref_processor =
2042 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
2043 ParallelRefProcEnabled, // MT processing
2044 _max_workers, // Degree of MT processing
2045 true, // MT discovery
2046 _max_workers, // Degree of MT discovery
2047 false, // Reference discovery is not atomic
2048 NULL, // No closure, should be installed before use
2049 true); // Scale worker threads
2050
2051 shenandoah_assert_rp_isalive_not_installed();
2052 }
2053
2054 GCTracer* ShenandoahHeap::tracer() {
2055 return shenandoah_policy()->tracer();
2056 }
2057
2058 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
2059 return _free_set->used();
2060 }
2061
2062 bool ShenandoahHeap::try_cancel_gc() {
2063 while (true) {
2064 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
2065 if (prev == CANCELLABLE) return true;
2066 else if (prev == CANCELLED) return false;
2067 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
2068 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
2069 if (Thread::current()->is_Java_thread()) {
2070 // We need to provide a safepoint here, otherwise we might
2071 // spin forever if a SP is pending.
2072 ThreadBlockInVM sp(JavaThread::current());
2073 SpinPause();
2074 }
2075 }
2076 }
2077
2078 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
2079 if (try_cancel_gc()) {
2080 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
2081 log_info(gc)("%s", msg.buffer());
2082 Events::log(Thread::current(), "%s", msg.buffer());
2083 }
2084 }
2085
2086 uint ShenandoahHeap::max_workers() {
2087 return _max_workers;
2088 }
2089
2090 void ShenandoahHeap::stop() {
2091 // The shutdown sequence should be able to terminate when GC is running.
2092
2093 // Step 0. Notify policy to disable event recording.
2094 _shenandoah_policy->record_shutdown();
2095
2096 // Step 1. Notify control thread that we are in shutdown.
2097 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
2098 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
2099 control_thread()->prepare_for_graceful_shutdown();
2100
2101 // Step 2. Notify GC workers that we are cancelling GC.
2102 cancel_gc(GCCause::_shenandoah_stop_vm);
2103
2104 // Step 3. Wait until GC worker exits normally.
2105 control_thread()->stop();
2106
2107 // Step 4. Stop String Dedup thread if it is active
2108 if (ShenandoahStringDedup::is_enabled()) {
2109 ShenandoahStringDedup::stop();
2110 }
2111 }
2112
2113 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
2114 if (!unload_classes()) return;
2115 bool purged_class;
2116
2117 // Unload classes and purge SystemDictionary.
2118 {
2119 ShenandoahGCPhase phase(full_gc ?
2120 ShenandoahPhaseTimings::full_gc_purge_class_unload :
2121 ShenandoahPhaseTimings::purge_class_unload);
2122 purged_class = SystemDictionary::do_unloading(gc_timer());
2123 }
2124
2125 {
2126 ShenandoahGCPhase phase(full_gc ?
2127 ShenandoahPhaseTimings::full_gc_purge_par :
2128 ShenandoahPhaseTimings::purge_par);
2129 ShenandoahIsAliveSelector is_alive;
2130 uint num_workers = _workers->active_workers();
2131 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
2132 _workers->run_task(&unlink_task);
2133 }
2134
2135 {
2136 ShenandoahGCPhase phase(full_gc ?
2137 ShenandoahPhaseTimings::full_gc_purge_cldg :
2138 ShenandoahPhaseTimings::purge_cldg);
2139 ClassLoaderDataGraph::purge();
2140 }
2141 // Resize and verify metaspace
2142 MetaspaceGC::compute_new_size();
2143 MetaspaceUtils::verify_metrics();
2144 }
2145
2146 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
2147 // so they should not have forwarded oops.
2148 // However, we do need to "null" dead oops in the roots, if can not be done
2149 // in concurrent cycles.
2150 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
2151 ShenandoahGCPhase root_phase(full_gc ?
2152 ShenandoahPhaseTimings::full_gc_purge :
2153 ShenandoahPhaseTimings::purge);
2154 uint num_workers = _workers->active_workers();
2155 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
2156 ShenandoahPhaseTimings::full_gc_purge_par :
2157 ShenandoahPhaseTimings::purge_par;
2158 ShenandoahGCPhase phase(timing_phase);
2159 ShenandoahGCWorkerPhase worker_phase(timing_phase);
2160
2161 // Cleanup weak roots
2162 if (has_forwarded_objects()) {
2163 ShenandoahForwardedIsAliveClosure is_alive;
2164 ShenandoahUpdateRefsClosure keep_alive;
2165 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2166 cleaning_task(&is_alive, &keep_alive, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2167 _workers->run_task(&cleaning_task);
2168 } else {
2169 ShenandoahIsAliveClosure is_alive;
2170 #ifdef ASSERT
2171 ShenandoahAssertNotForwardedClosure verify_cl;
2172 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2173 cleaning_task(&is_alive, &verify_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2174 #else
2175 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2176 cleaning_task(&is_alive, &do_nothing_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2177 #endif
2178 _workers->run_task(&cleaning_task);
2179 }
2180 }
2181
2182 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2183 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2184 stw_process_weak_roots(full_gc);
2185 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2186 stw_unload_classes(full_gc);
2187 }
2188 }
2189
2190 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2191 if (is_traversal_mode()) {
2192 set_gc_state_mask(HAS_FORWARDED | UPDATEREFS, cond);
2193 } else {
2194 set_gc_state_mask(HAS_FORWARDED, cond);
2195 }
2196
2197 }
2198
2199 void ShenandoahHeap::set_process_references(bool pr) {
2200 _process_references.set_cond(pr);
2201 }
2202
2203 void ShenandoahHeap::set_unload_classes(bool uc) {
2204 _unload_classes.set_cond(uc);
2205 }
2206
2207 bool ShenandoahHeap::process_references() const {
2208 return _process_references.is_set();
2209 }
2210
2211 bool ShenandoahHeap::unload_classes() const {
2212 return _unload_classes.is_set();
2213 }
2214
2215 address ShenandoahHeap::in_cset_fast_test_addr() {
2216 ShenandoahHeap* heap = ShenandoahHeap::heap();
2217 assert(heap->collection_set() != NULL, "Sanity");
2218 return (address) heap->collection_set()->biased_map_address();
2219 }
2220
2221 address ShenandoahHeap::cancelled_gc_addr() {
2222 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
2223 }
2224
2225 address ShenandoahHeap::gc_state_addr() {
2226 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2227 }
2228
2229 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2230 return Atomic::load_acquire(&_bytes_allocated_since_gc_start);
2231 }
2232
2233 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2234 Atomic::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2235 }
2236
2237 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2238 _degenerated_gc_in_progress.set_cond(in_progress);
2239 }
2240
2241 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2242 _full_gc_in_progress.set_cond(in_progress);
2243 }
2244
2245 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2246 assert (is_full_gc_in_progress(), "should be");
2247 _full_gc_move_in_progress.set_cond(in_progress);
2248 }
2249
2250 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2251 set_gc_state_mask(UPDATEREFS, in_progress);
2252 }
2253
2254 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2255 ShenandoahCodeRoots::register_nmethod(nm);
2256 }
2257
2258 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2259 ShenandoahCodeRoots::unregister_nmethod(nm);
2260 }
2261
2262 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
2263 ShenandoahCodeRoots::flush_nmethod(nm);
2264 }
2265
2266 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2267 heap_region_containing(o)->record_pin();
2268 return o;
2269 }
2270
2271 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2272 heap_region_containing(o)->record_unpin();
2273 }
2274
2275 void ShenandoahHeap::sync_pinned_region_status() {
2276 ShenandoahHeapLocker locker(lock());
2277
2278 for (size_t i = 0; i < num_regions(); i++) {
2279 ShenandoahHeapRegion *r = get_region(i);
2280 if (r->is_active()) {
2281 if (r->is_pinned()) {
2282 if (r->pin_count() == 0) {
2283 r->make_unpinned();
2284 }
2285 } else {
2286 if (r->pin_count() > 0) {
2287 r->make_pinned();
2288 }
2289 }
2290 }
2291 }
2292
2293 assert_pinned_region_status();
2294 }
2295
2296 #ifdef ASSERT
2297 void ShenandoahHeap::assert_pinned_region_status() {
2298 for (size_t i = 0; i < num_regions(); i++) {
2299 ShenandoahHeapRegion* r = get_region(i);
2300 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2301 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2302 }
2303 }
2304 #endif
2305
2306 GCTimer* ShenandoahHeap::gc_timer() const {
2307 return _gc_timer;
2308 }
2309
2310 void ShenandoahHeap::prepare_concurrent_roots() {
2311 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2312 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
2313 set_concurrent_root_in_progress(true);
2314 }
2315 }
2316
2317 void ShenandoahHeap::prepare_concurrent_unloading() {
2318 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2319 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2320 _unloader.prepare();
2321 }
2322 }
2323
2324 void ShenandoahHeap::finish_concurrent_unloading() {
2325 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2326 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2327 _unloader.finish();
2328 }
2329 }
2330
2331 #ifdef ASSERT
2332 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2333 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2334
2335 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2336 if (UseDynamicNumberOfGCThreads) {
2337 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2338 } else {
2339 // Use ParallelGCThreads inside safepoints
2340 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
2341 }
2342 } else {
2343 if (UseDynamicNumberOfGCThreads) {
2344 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2345 } else {
2346 // Use ConcGCThreads outside safepoints
2347 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2348 }
2349 }
2350 }
2351 #endif
2352
2353 ShenandoahVerifier* ShenandoahHeap::verifier() {
2354 guarantee(ShenandoahVerify, "Should be enabled");
2355 assert (_verifier != NULL, "sanity");
2356 return _verifier;
2357 }
2358
2359 template<class T>
2360 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2361 private:
2362 T cl;
2363 ShenandoahHeap* _heap;
2364 ShenandoahRegionIterator* _regions;
2365 bool _concurrent;
2366 public:
2367 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2368 AbstractGangTask("Concurrent Update References Task"),
2369 cl(T()),
2370 _heap(ShenandoahHeap::heap()),
2371 _regions(regions),
2372 _concurrent(concurrent) {
2373 }
2374
2375 void work(uint worker_id) {
2376 if (_concurrent) {
2377 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2378 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2379 do_work();
2380 } else {
2381 ShenandoahParallelWorkerSession worker_session(worker_id);
2382 do_work();
2383 }
2384 }
2385
2386 private:
2387 void do_work() {
2388 ShenandoahHeapRegion* r = _regions->next();
2389 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2390 while (r != NULL) {
2391 HeapWord* update_watermark = r->get_update_watermark();
2392 assert (update_watermark >= r->bottom(), "sanity");
2393 if (r->is_active() && !r->is_cset()) {
2394 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2395 }
2396 r->set_update_watermark(r->bottom());
2397 if (ShenandoahPacing) {
2398 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2399 }
2400 if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
2401 return;
2402 }
2403 r = _regions->next();
2404 }
2405 }
2406 };
2407
2408 void ShenandoahHeap::update_heap_references(bool concurrent) {
2409 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
2410 workers()->run_task(&task);
2411 }
2412
2413 void ShenandoahHeap::op_init_updaterefs() {
2414 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2415
2416 set_evacuation_in_progress(false);
2417
2418 {
2419 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_retire_gclabs);
2420 retire_and_reset_gclabs();
2421 }
2422
2423 if (ShenandoahVerify) {
2424 if (!is_degenerated_gc_in_progress()) {
2425 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2426 }
2427 verifier()->verify_before_updaterefs();
2428 }
2429
2430 set_update_refs_in_progress(true);
2431
2432 {
2433 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_prepare);
2434
2435 make_parsable(true);
2436
2437 // Reset iterator.
2438 _update_refs_iterator.reset();
2439 }
2440
2441 if (ShenandoahPacing) {
2442 pacer()->setup_for_updaterefs();
2443 }
2444 }
2445
2446 void ShenandoahHeap::op_final_updaterefs() {
2447 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2448
2449 finish_concurrent_unloading();
2450
2451 // Check if there is left-over work, and finish it
2452 if (_update_refs_iterator.has_next()) {
2453 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2454
2455 // Finish updating references where we left off.
2456 clear_cancelled_gc();
2457 update_heap_references(false);
2458 }
2459
2460 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2461 // everything. On degenerated paths, cancelled gc would not be set anyway.
2462 if (cancelled_gc()) {
2463 clear_cancelled_gc();
2464 }
2465 assert(!cancelled_gc(), "Should have been done right before");
2466
2467 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2468 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2469 }
2470
2471 if (is_degenerated_gc_in_progress()) {
2472 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2473 } else {
2474 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2475 }
2476
2477 // Has to be done before cset is clear
2478 if (ShenandoahVerify) {
2479 verifier()->verify_roots_in_to_space();
2480 }
2481
2482 // Drop unnecessary "pinned" state from regions that does not have CP marks
2483 // anymore, as this would allow trashing them below.
2484 {
2485 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_sync_pinned);
2486 sync_pinned_region_status();
2487 }
2488
2489 {
2490 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2491 trash_cset_regions();
2492 }
2493
2494 set_has_forwarded_objects(false);
2495 set_update_refs_in_progress(false);
2496
2497 if (ShenandoahVerify) {
2498 verifier()->verify_after_updaterefs();
2499 }
2500
2501 if (VerifyAfterGC) {
2502 Universe::verify();
2503 }
2504
2505 {
2506 ShenandoahHeapLocker locker(lock());
2507 _free_set->rebuild();
2508 }
2509 }
2510
2511 #ifdef ASSERT
2512 void ShenandoahHeap::assert_heaplock_owned_by_current_thread() {
2513 _lock.assert_owned_by_current_thread();
2514 }
2515
2516 void ShenandoahHeap::assert_heaplock_not_owned_by_current_thread() {
2517 _lock.assert_not_owned_by_current_thread();
2518 }
2519
2520 void ShenandoahHeap::assert_heaplock_or_safepoint() {
2521 _lock.assert_owned_by_current_thread_or_safepoint();
2522 }
2523 #endif
2524
2525 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2526 print_on(st);
2527 print_heap_regions_on(st);
2528 }
2529
2530 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2531 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2532
2533 size_t regions_from = _bitmap_regions_per_slice * slice;
2534 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2535 for (size_t g = regions_from; g < regions_to; g++) {
2536 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2537 if (skip_self && g == r->region_number()) continue;
2538 if (get_region(g)->is_committed()) {
2539 return true;
2540 }
2541 }
2542 return false;
2543 }
2544
2545 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2546 assert_heaplock_owned_by_current_thread();
2547
2548 // Bitmaps in special regions do not need commits
2549 if (_bitmap_region_special) {
2550 return true;
2551 }
2552
2553 if (is_bitmap_slice_committed(r, true)) {
2554 // Some other region from the group is already committed, meaning the bitmap
2555 // slice is already committed, we exit right away.
2556 return true;
2557 }
2558
2559 // Commit the bitmap slice:
2560 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2561 size_t off = _bitmap_bytes_per_slice * slice;
2562 size_t len = _bitmap_bytes_per_slice;
2563 if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) {
2564 return false;
2565 }
2566 return true;
2567 }
2568
2569 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2570 assert_heaplock_owned_by_current_thread();
2571
2572 // Bitmaps in special regions do not need uncommits
2573 if (_bitmap_region_special) {
2574 return true;
2575 }
2576
2577 if (is_bitmap_slice_committed(r, true)) {
2578 // Some other region from the group is still committed, meaning the bitmap
2579 // slice is should stay committed, exit right away.
2580 return true;
2581 }
2582
2583 // Uncommit the bitmap slice:
2584 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2585 size_t off = _bitmap_bytes_per_slice * slice;
2586 size_t len = _bitmap_bytes_per_slice;
2587 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2588 return false;
2589 }
2590 return true;
2591 }
2592
2593 void ShenandoahHeap::safepoint_synchronize_begin() {
2594 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2595 SuspendibleThreadSet::synchronize();
2596 }
2597 }
2598
2599 void ShenandoahHeap::safepoint_synchronize_end() {
2600 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2601 SuspendibleThreadSet::desynchronize();
2602 }
2603 }
2604
2605 void ShenandoahHeap::vmop_entry_init_mark() {
2606 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2607 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2608 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
2609
2610 try_inject_alloc_failure();
2611 VM_ShenandoahInitMark op;
2612 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2613 }
2614
2615 void ShenandoahHeap::vmop_entry_final_mark() {
2616 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2617 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2618 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
2619
2620 try_inject_alloc_failure();
2621 VM_ShenandoahFinalMarkStartEvac op;
2622 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2623 }
2624
2625 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2626 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2627 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2628 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
2629
2630 try_inject_alloc_failure();
2631 VM_ShenandoahInitUpdateRefs op;
2632 VMThread::execute(&op);
2633 }
2634
2635 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2636 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2637 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2638 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
2639
2640 try_inject_alloc_failure();
2641 VM_ShenandoahFinalUpdateRefs op;
2642 VMThread::execute(&op);
2643 }
2644
2645 void ShenandoahHeap::vmop_entry_init_traversal() {
2646 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2647 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2648 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc_gross);
2649
2650 try_inject_alloc_failure();
2651 VM_ShenandoahInitTraversalGC op;
2652 VMThread::execute(&op);
2653 }
2654
2655 void ShenandoahHeap::vmop_entry_final_traversal() {
2656 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2657 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2658 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc_gross);
2659
2660 try_inject_alloc_failure();
2661 VM_ShenandoahFinalTraversalGC op;
2662 VMThread::execute(&op);
2663 }
2664
2665 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2666 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2667 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2668 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
2669
2670 try_inject_alloc_failure();
2671 VM_ShenandoahFullGC op(cause);
2672 VMThread::execute(&op);
2673 }
2674
2675 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2676 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2677 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2678 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
2679
2680 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2681 VMThread::execute(°enerated_gc);
2682 }
2683
2684 void ShenandoahHeap::entry_init_mark() {
2685 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2686 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
2687 const char* msg = init_mark_event_message();
2688 GCTraceTime(Info, gc) time(msg, gc_timer());
2689 EventMark em("%s", msg);
2690
2691 ShenandoahWorkerScope scope(workers(),
2692 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2693 "init marking");
2694
2695 op_init_mark();
2696 }
2697
2698 void ShenandoahHeap::entry_final_mark() {
2699 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2700 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
2701 const char* msg = final_mark_event_message();
2702 GCTraceTime(Info, gc) time(msg, gc_timer());
2703 EventMark em("%s", msg);
2704
2705 ShenandoahWorkerScope scope(workers(),
2706 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2707 "final marking");
2708
2709 op_final_mark();
2710 }
2711
2712 void ShenandoahHeap::entry_init_updaterefs() {
2713 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2714 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
2715
2716 static const char* msg = "Pause Init Update Refs";
2717 GCTraceTime(Info, gc) time(msg, gc_timer());
2718 EventMark em("%s", msg);
2719
2720 // No workers used in this phase, no setup required
2721
2722 op_init_updaterefs();
2723 }
2724
2725 void ShenandoahHeap::entry_final_updaterefs() {
2726 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2727 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
2728
2729 static const char* msg = "Pause Final Update Refs";
2730 GCTraceTime(Info, gc) time(msg, gc_timer());
2731 EventMark em("%s", msg);
2732
2733 ShenandoahWorkerScope scope(workers(),
2734 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2735 "final reference update");
2736
2737 op_final_updaterefs();
2738 }
2739
2740 void ShenandoahHeap::entry_init_traversal() {
2741 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2742 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc);
2743
2744 static const char* msg = init_traversal_event_message();
2745 GCTraceTime(Info, gc) time(msg, gc_timer());
2746 EventMark em("%s", msg);
2747
2748 ShenandoahWorkerScope scope(workers(),
2749 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2750 "init traversal");
2751
2752 op_init_traversal();
2753 }
2754
2755 void ShenandoahHeap::entry_final_traversal() {
2756 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2757 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc);
2758
2759 static const char* msg = final_traversal_event_message();
2760 GCTraceTime(Info, gc) time(msg, gc_timer());
2761 EventMark em("%s", msg);
2762
2763 ShenandoahWorkerScope scope(workers(),
2764 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2765 "final traversal");
2766
2767 op_final_traversal();
2768 }
2769
2770 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2771 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2772 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
2773
2774 static const char* msg = "Pause Full";
2775 GCTraceTime(Info, gc) time(msg, gc_timer(), cause, true);
2776 EventMark em("%s", msg);
2777
2778 ShenandoahWorkerScope scope(workers(),
2779 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2780 "full gc");
2781
2782 op_full(cause);
2783 }
2784
2785 void ShenandoahHeap::entry_degenerated(int point) {
2786 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2787 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
2788
2789 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2790 const char* msg = degen_event_message(dpoint);
2791 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2792 EventMark em("%s", msg);
2793
2794 ShenandoahWorkerScope scope(workers(),
2795 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2796 "stw degenerated gc");
2797
2798 set_degenerated_gc_in_progress(true);
2799 op_degenerated(dpoint);
2800 set_degenerated_gc_in_progress(false);
2801 }
2802
2803 void ShenandoahHeap::entry_mark() {
2804 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2805
2806 const char* msg = conc_mark_event_message();
2807 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2808 EventMark em("%s", msg);
2809
2810 ShenandoahWorkerScope scope(workers(),
2811 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2812 "concurrent marking");
2813
2814 try_inject_alloc_failure();
2815 op_mark();
2816 }
2817
2818 void ShenandoahHeap::entry_evac() {
2819 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
2820 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2821
2822 static const char* msg = "Concurrent evacuation";
2823 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2824 EventMark em("%s", msg);
2825
2826 ShenandoahWorkerScope scope(workers(),
2827 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2828 "concurrent evacuation");
2829
2830 try_inject_alloc_failure();
2831 op_conc_evac();
2832 }
2833
2834 void ShenandoahHeap::entry_updaterefs() {
2835 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
2836
2837 static const char* msg = "Concurrent update references";
2838 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2839 EventMark em("%s", msg);
2840
2841 ShenandoahWorkerScope scope(workers(),
2842 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2843 "concurrent reference update");
2844
2845 try_inject_alloc_failure();
2846 op_updaterefs();
2847 }
2848
2849 void ShenandoahHeap::entry_roots() {
2850 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_roots);
2851
2852 static const char* msg = "Concurrent roots processing";
2853 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2854 EventMark em("%s", msg);
2855
2856 ShenandoahWorkerScope scope(workers(),
2857 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2858 "concurrent root processing");
2859
2860 try_inject_alloc_failure();
2861 op_roots();
2862 }
2863
2864 void ShenandoahHeap::entry_cleanup() {
2865 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup);
2866
2867 static const char* msg = "Concurrent cleanup";
2868 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2869 EventMark em("%s", msg);
2870
2871 // This phase does not use workers, no need for setup
2872
2873 try_inject_alloc_failure();
2874 op_cleanup();
2875 }
2876
2877 void ShenandoahHeap::entry_reset() {
2878 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset);
2879
2880 static const char* msg = "Concurrent reset";
2881 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2882 EventMark em("%s", msg);
2883
2884 ShenandoahWorkerScope scope(workers(),
2885 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2886 "concurrent reset");
2887
2888 try_inject_alloc_failure();
2889 op_reset();
2890 }
2891
2892 void ShenandoahHeap::entry_preclean() {
2893 if (ShenandoahPreclean && process_references()) {
2894 static const char* msg = "Concurrent precleaning";
2895 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2896 EventMark em("%s", msg);
2897
2898 ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
2899
2900 ShenandoahWorkerScope scope(workers(),
2901 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2902 "concurrent preclean",
2903 /* check_workers = */ false);
2904
2905 try_inject_alloc_failure();
2906 op_preclean();
2907 }
2908 }
2909
2910 void ShenandoahHeap::entry_traversal() {
2911 static const char* msg = conc_traversal_event_message();
2912 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2913 EventMark em("%s", msg);
2914
2915 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2916
2917 ShenandoahWorkerScope scope(workers(),
2918 ShenandoahWorkerPolicy::calc_workers_for_conc_traversal(),
2919 "concurrent traversal");
2920
2921 try_inject_alloc_failure();
2922 op_traversal();
2923 }
2924
2925 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2926 static const char *msg = "Concurrent uncommit";
2927 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2928 EventMark em("%s", msg);
2929
2930 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit);
2931
2932 op_uncommit(shrink_before);
2933 }
2934
2935 void ShenandoahHeap::try_inject_alloc_failure() {
2936 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2937 _inject_alloc_failure.set();
2938 os::naked_short_sleep(1);
2939 if (cancelled_gc()) {
2940 log_info(gc)("Allocation failure was successfully injected");
2941 }
2942 }
2943 }
2944
2945 bool ShenandoahHeap::should_inject_alloc_failure() {
2946 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2947 }
2948
2949 void ShenandoahHeap::initialize_serviceability() {
2950 _memory_pool = new ShenandoahMemoryPool(this);
2951 _cycle_memory_manager.add_pool(_memory_pool);
2952 _stw_memory_manager.add_pool(_memory_pool);
2953 }
2954
2955 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2956 GrowableArray<GCMemoryManager*> memory_managers(2);
2957 memory_managers.append(&_cycle_memory_manager);
2958 memory_managers.append(&_stw_memory_manager);
2959 return memory_managers;
2960 }
2961
2962 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2963 GrowableArray<MemoryPool*> memory_pools(1);
2964 memory_pools.append(_memory_pool);
2965 return memory_pools;
2966 }
2967
2968 MemoryUsage ShenandoahHeap::memory_usage() {
2969 return _memory_pool->get_memory_usage();
2970 }
2971
2972 void ShenandoahHeap::enter_evacuation() {
2973 _oom_evac_handler.enter_evacuation();
2974 }
2975
2976 void ShenandoahHeap::leave_evacuation() {
2977 _oom_evac_handler.leave_evacuation();
2978 }
2979
2980 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2981 _heap(ShenandoahHeap::heap()),
2982 _index(0) {}
2983
2984 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2985 _heap(heap),
2986 _index(0) {}
2987
2988 void ShenandoahRegionIterator::reset() {
2989 _index = 0;
2990 }
2991
2992 bool ShenandoahRegionIterator::has_next() const {
2993 return _index < _heap->num_regions();
2994 }
2995
2996 char ShenandoahHeap::gc_state() const {
2997 return _gc_state.raw_value();
2998 }
2999
3000 void ShenandoahHeap::deduplicate_string(oop str) {
3001 assert(java_lang_String::is_instance(str), "invariant");
3002
3003 if (ShenandoahStringDedup::is_enabled()) {
3004 ShenandoahStringDedup::deduplicate(str);
3005 }
3006 }
3007
3008 const char* ShenandoahHeap::init_mark_event_message() const {
3009 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3010
3011 bool proc_refs = process_references();
3012 bool unload_cls = unload_classes();
3013
3014 if (proc_refs && unload_cls) {
3015 return "Pause Init Mark (process weakrefs) (unload classes)";
3016 } else if (proc_refs) {
3017 return "Pause Init Mark (process weakrefs)";
3018 } else if (unload_cls) {
3019 return "Pause Init Mark (unload classes)";
3020 } else {
3021 return "Pause Init Mark";
3022 }
3023 }
3024
3025 const char* ShenandoahHeap::final_mark_event_message() const {
3026 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3027
3028 bool proc_refs = process_references();
3029 bool unload_cls = unload_classes();
3030
3031 if (proc_refs && unload_cls) {
3032 return "Pause Final Mark (process weakrefs) (unload classes)";
3033 } else if (proc_refs) {
3034 return "Pause Final Mark (process weakrefs)";
3035 } else if (unload_cls) {
3036 return "Pause Final Mark (unload classes)";
3037 } else {
3038 return "Pause Final Mark";
3039 }
3040 }
3041
3042 const char* ShenandoahHeap::conc_mark_event_message() const {
3043 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3044
3045 bool proc_refs = process_references();
3046 bool unload_cls = unload_classes();
3047
3048 if (proc_refs && unload_cls) {
3049 return "Concurrent marking (process weakrefs) (unload classes)";
3050 } else if (proc_refs) {
3051 return "Concurrent marking (process weakrefs)";
3052 } else if (unload_cls) {
3053 return "Concurrent marking (unload classes)";
3054 } else {
3055 return "Concurrent marking";
3056 }
3057 }
3058
3059 const char* ShenandoahHeap::init_traversal_event_message() const {
3060 bool proc_refs = process_references();
3061 bool unload_cls = unload_classes();
3062
3063 if (proc_refs && unload_cls) {
3064 return "Pause Init Traversal (process weakrefs) (unload classes)";
3065 } else if (proc_refs) {
3066 return "Pause Init Traversal (process weakrefs)";
3067 } else if (unload_cls) {
3068 return "Pause Init Traversal (unload classes)";
3069 } else {
3070 return "Pause Init Traversal";
3071 }
3072 }
3073
3074 const char* ShenandoahHeap::final_traversal_event_message() const {
3075 bool proc_refs = process_references();
3076 bool unload_cls = unload_classes();
3077
3078 if (proc_refs && unload_cls) {
3079 return "Pause Final Traversal (process weakrefs) (unload classes)";
3080 } else if (proc_refs) {
3081 return "Pause Final Traversal (process weakrefs)";
3082 } else if (unload_cls) {
3083 return "Pause Final Traversal (unload classes)";
3084 } else {
3085 return "Pause Final Traversal";
3086 }
3087 }
3088
3089 const char* ShenandoahHeap::conc_traversal_event_message() const {
3090 bool proc_refs = process_references();
3091 bool unload_cls = unload_classes();
3092
3093 if (proc_refs && unload_cls) {
3094 return "Concurrent Traversal (process weakrefs) (unload classes)";
3095 } else if (proc_refs) {
3096 return "Concurrent Traversal (process weakrefs)";
3097 } else if (unload_cls) {
3098 return "Concurrent Traversal (unload classes)";
3099 } else {
3100 return "Concurrent Traversal";
3101 }
3102 }
3103
3104 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
3105 switch (point) {
3106 case _degenerated_unset:
3107 return "Pause Degenerated GC (<UNSET>)";
3108 case _degenerated_traversal:
3109 return "Pause Degenerated GC (Traversal)";
3110 case _degenerated_outside_cycle:
3111 return "Pause Degenerated GC (Outside of Cycle)";
3112 case _degenerated_mark:
3113 return "Pause Degenerated GC (Mark)";
3114 case _degenerated_evac:
3115 return "Pause Degenerated GC (Evacuation)";
3116 case _degenerated_updaterefs:
3117 return "Pause Degenerated GC (Update Refs)";
3118 default:
3119 ShouldNotReachHere();
3120 return "ERROR";
3121 }
3122 }
3123
3124 jushort* ShenandoahHeap::get_liveness_cache(uint worker_id) {
3125 #ifdef ASSERT
3126 assert(_liveness_cache != NULL, "sanity");
3127 assert(worker_id < _max_workers, "sanity");
3128 for (uint i = 0; i < num_regions(); i++) {
3129 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
3130 }
3131 #endif
3132 return _liveness_cache[worker_id];
3133 }
3134
3135 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
3136 assert(worker_id < _max_workers, "sanity");
3137 assert(_liveness_cache != NULL, "sanity");
3138 jushort* ld = _liveness_cache[worker_id];
3139 for (uint i = 0; i < num_regions(); i++) {
3140 ShenandoahHeapRegion* r = get_region(i);
3141 jushort live = ld[i];
3142 if (live > 0) {
3143 r->increase_live_data_gc_words(live);
3144 ld[i] = 0;
3145 }
3146 }
3147 }