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/shenandoahAllocTracker.hpp"
38 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
39 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
40 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
41 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
42 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
43 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
44 #include "gc/shenandoah/shenandoahControlThread.hpp"
45 #include "gc/shenandoah/shenandoahFreeSet.hpp"
46 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
47 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
48 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
49 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
50 #include "gc/shenandoah/shenandoahMarkCompact.hpp"
51 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
52 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
53 #include "gc/shenandoah/shenandoahMetrics.hpp"
54 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
55 #include "gc/shenandoah/shenandoahNormalMode.hpp"
56 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
57 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
58 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
59 #include "gc/shenandoah/shenandoahPassiveMode.hpp"
60 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
61 #include "gc/shenandoah/shenandoahStringDedup.hpp"
62 #include "gc/shenandoah/shenandoahTaskqueue.hpp"
63 #include "gc/shenandoah/shenandoahTraversalMode.hpp"
64 #include "gc/shenandoah/shenandoahUtils.hpp"
65 #include "gc/shenandoah/shenandoahVerifier.hpp"
66 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
67 #include "gc/shenandoah/shenandoahVMOperations.hpp"
68 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
69 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
70 #if INCLUDE_JFR
71 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
72 #endif
73
74 #include "memory/metaspace.hpp"
75 #include "oops/compressedOops.inline.hpp"
76 #include "runtime/atomic.hpp"
77 #include "runtime/globals.hpp"
78 #include "runtime/interfaceSupport.inline.hpp"
79 #include "runtime/orderAccess.hpp"
80 #include "runtime/safepointMechanism.hpp"
81 #include "runtime/vmThread.hpp"
82 #include "services/mallocTracker.hpp"
83
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 (ShenandoahAllocationTrace) {
364 _alloc_tracker = new ShenandoahAllocTracker();
365 }
366
367 if (ShenandoahPacing) {
368 _pacer = new ShenandoahPacer(this);
369 _pacer->setup_for_idle();
370 } else {
371 _pacer = NULL;
372 }
373
374 _traversal_gc = strcmp(ShenandoahGCMode, "traversal") == 0 ?
375 new ShenandoahTraversalGC(this, _num_regions) :
376 NULL;
377
378 _control_thread = new ShenandoahControlThread();
379
380 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max",
381 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size),
382 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size),
383 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity())
384 );
385
386 log_info(gc, init)("Safepointing mechanism: %s",
387 SafepointMechanism::uses_thread_local_poll() ? "thread-local poll" :
388 (SafepointMechanism::uses_global_page_poll() ? "global-page poll" : "unknown"));
389
390 return JNI_OK;
391 }
392
393 void ShenandoahHeap::initialize_heuristics() {
394 if (ShenandoahGCMode != NULL) {
395 if (strcmp(ShenandoahGCMode, "traversal") == 0) {
396 _gc_mode = new ShenandoahTraversalMode();
397 } else if (strcmp(ShenandoahGCMode, "normal") == 0) {
398 _gc_mode = new ShenandoahNormalMode();
399 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
400 _gc_mode = new ShenandoahPassiveMode();
401 } else {
402 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
403 }
404 } else {
405 ShouldNotReachHere();
406 }
407 _gc_mode->initialize_flags();
408 _heuristics = _gc_mode->initialize_heuristics();
409
410 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
411 vm_exit_during_initialization(
412 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
413 _heuristics->name()));
414 }
415 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
416 vm_exit_during_initialization(
417 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
418 _heuristics->name()));
419 }
420 log_info(gc, init)("Shenandoah heuristics: %s",
421 _heuristics->name());
422 }
423
424 #ifdef _MSC_VER
425 #pragma warning( push )
426 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
427 #endif
428
429 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
430 CollectedHeap(),
431 _initial_size(0),
432 _used(0),
433 _committed(0),
434 _bytes_allocated_since_gc_start(0),
435 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
436 _workers(NULL),
437 _safepoint_workers(NULL),
438 _heap_region_special(false),
439 _num_regions(0),
440 _regions(NULL),
441 _update_refs_iterator(this),
442 _control_thread(NULL),
443 _shenandoah_policy(policy),
444 _heuristics(NULL),
445 _free_set(NULL),
446 _scm(new ShenandoahConcurrentMark()),
447 _traversal_gc(NULL),
448 _full_gc(new ShenandoahMarkCompact()),
449 _pacer(NULL),
450 _verifier(NULL),
451 _alloc_tracker(NULL),
452 _phase_timings(NULL),
453 _monitoring_support(NULL),
454 _memory_pool(NULL),
455 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
456 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
457 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
458 _soft_ref_policy(),
459 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
460 _ref_processor(NULL),
461 _marking_context(NULL),
462 _bitmap_size(0),
463 _bitmap_regions_per_slice(0),
464 _bitmap_bytes_per_slice(0),
465 _bitmap_region_special(false),
466 _aux_bitmap_region_special(false),
467 _liveness_cache(NULL),
468 _collection_set(NULL)
469 {
470 log_info(gc, init)("GC threads: " UINT32_FORMAT " parallel, " UINT32_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
471 log_info(gc, init)("Reference processing: %s", ParallelRefProcEnabled ? "parallel" : "serial");
472
473 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
474
475 _max_workers = MAX2(_max_workers, 1U);
476 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
477 /* are_GC_task_threads */ true,
478 /* are_ConcurrentGC_threads */ true);
479 if (_workers == NULL) {
480 vm_exit_during_initialization("Failed necessary allocation.");
481 } else {
482 _workers->initialize_workers();
483 }
484
485 if (ShenandoahParallelSafepointThreads > 1) {
486 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
487 ShenandoahParallelSafepointThreads,
488 /* are_GC_task_threads */ false,
489 /* are_ConcurrentGC_threads */ false);
490 _safepoint_workers->initialize_workers();
491 }
492 }
493
494 #ifdef _MSC_VER
495 #pragma warning( pop )
496 #endif
497
498 class ShenandoahResetBitmapTask : public AbstractGangTask {
499 private:
500 ShenandoahRegionIterator _regions;
501
502 public:
503 ShenandoahResetBitmapTask() :
504 AbstractGangTask("Parallel Reset Bitmap Task") {}
505
506 void work(uint worker_id) {
507 ShenandoahHeapRegion* region = _regions.next();
508 ShenandoahHeap* heap = ShenandoahHeap::heap();
509 ShenandoahMarkingContext* const ctx = heap->marking_context();
510 while (region != NULL) {
511 if (heap->is_bitmap_slice_committed(region)) {
512 ctx->clear_bitmap(region);
513 }
514 region = _regions.next();
515 }
516 }
517 };
518
519 void ShenandoahHeap::reset_mark_bitmap() {
520 assert_gc_workers(_workers->active_workers());
521 mark_incomplete_marking_context();
522
523 ShenandoahResetBitmapTask task;
524 _workers->run_task(&task);
525 }
526
527 void ShenandoahHeap::print_on(outputStream* st) const {
528 st->print_cr("Shenandoah Heap");
529 st->print_cr(" " SIZE_FORMAT "%s total, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
530 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
531 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
532 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
533 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
534 num_regions(),
535 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
536 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
537
538 st->print("Status: ");
539 if (has_forwarded_objects()) st->print("has forwarded objects, ");
540 if (is_concurrent_mark_in_progress()) st->print("marking, ");
541 if (is_evacuation_in_progress()) st->print("evacuating, ");
542 if (is_update_refs_in_progress()) st->print("updating refs, ");
543 if (is_concurrent_traversal_in_progress()) st->print("traversal, ");
544 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
545 if (is_full_gc_in_progress()) st->print("full gc, ");
546 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
547 if (is_concurrent_root_in_progress()) st->print("concurrent roots, ");
548
549 if (cancelled_gc()) {
550 st->print("cancelled");
551 } else {
552 st->print("not cancelled");
553 }
554 st->cr();
555
556 st->print_cr("Reserved region:");
557 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
558 p2i(reserved_region().start()),
559 p2i(reserved_region().end()));
560
561 ShenandoahCollectionSet* cset = collection_set();
562 st->print_cr("Collection set:");
563 if (cset != NULL) {
564 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
565 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
566 } else {
567 st->print_cr(" (NULL)");
568 }
569
570 st->cr();
571 MetaspaceUtils::print_on(st);
572
573 if (Verbose) {
574 print_heap_regions_on(st);
575 }
576 }
577
578 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
579 public:
580 void do_thread(Thread* thread) {
581 assert(thread != NULL, "Sanity");
582 assert(thread->is_Worker_thread(), "Only worker thread expected");
583 ShenandoahThreadLocalData::initialize_gclab(thread);
584 }
585 };
586
587 void ShenandoahHeap::post_initialize() {
588 CollectedHeap::post_initialize();
589 MutexLocker ml(Threads_lock);
590
591 ShenandoahInitWorkerGCLABClosure init_gclabs;
592 _workers->threads_do(&init_gclabs);
593
594 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
595 // Now, we will let WorkGang to initialize gclab when new worker is created.
596 _workers->set_initialize_gclab();
597
598 _scm->initialize(_max_workers);
599 _full_gc->initialize(_gc_timer);
600
601 ref_processing_init();
602
603 _heuristics->initialize();
604
605 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
606 }
607
608 size_t ShenandoahHeap::used() const {
609 return Atomic::load_acquire(&_used);
610 }
611
612 size_t ShenandoahHeap::committed() const {
613 OrderAccess::acquire();
614 return _committed;
615 }
616
617 void ShenandoahHeap::increase_committed(size_t bytes) {
618 assert_heaplock_or_safepoint();
619 _committed += bytes;
620 }
621
622 void ShenandoahHeap::decrease_committed(size_t bytes) {
623 assert_heaplock_or_safepoint();
624 _committed -= bytes;
625 }
626
627 void ShenandoahHeap::increase_used(size_t bytes) {
628 Atomic::add(&_used, bytes);
629 }
630
631 void ShenandoahHeap::set_used(size_t bytes) {
632 Atomic::release_store_fence(&_used, bytes);
633 }
634
635 void ShenandoahHeap::decrease_used(size_t bytes) {
636 assert(used() >= bytes, "never decrease heap size by more than we've left");
637 Atomic::sub(&_used, bytes);
638 }
639
640 void ShenandoahHeap::increase_allocated(size_t bytes) {
641 Atomic::add(&_bytes_allocated_since_gc_start, bytes);
642 }
643
644 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
645 size_t bytes = words * HeapWordSize;
646 if (!waste) {
647 increase_used(bytes);
648 }
649 increase_allocated(bytes);
650 if (ShenandoahPacing) {
651 control_thread()->pacing_notify_alloc(words);
652 if (waste) {
653 pacer()->claim_for_alloc(words, true);
654 }
655 }
656 }
657
658 size_t ShenandoahHeap::capacity() const {
659 return committed();
660 }
661
662 size_t ShenandoahHeap::max_capacity() const {
663 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
664 }
665
666 size_t ShenandoahHeap::min_capacity() const {
667 return _minimum_size;
668 }
669
670 size_t ShenandoahHeap::initial_capacity() const {
671 return _initial_size;
672 }
673
674 bool ShenandoahHeap::is_in(const void* p) const {
675 HeapWord* heap_base = (HeapWord*) base();
676 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
677 return p >= heap_base && p < last_region_end;
678 }
679
680 void ShenandoahHeap::op_uncommit(double shrink_before) {
681 assert (ShenandoahUncommit, "should be enabled");
682
683 // Application allocates from the beginning of the heap, and GC allocates at
684 // the end of it. It is more efficient to uncommit from the end, so that applications
685 // could enjoy the near committed regions. GC allocations are much less frequent,
686 // and therefore can accept the committing costs.
687
688 size_t count = 0;
689 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
690 ShenandoahHeapRegion* r = get_region(i - 1);
691 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
692 ShenandoahHeapLocker locker(lock());
693 if (r->is_empty_committed()) {
694 // Do not uncommit below minimal capacity
695 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
696 break;
697 }
698
699 r->make_uncommitted();
700 count++;
701 }
702 }
703 SpinPause(); // allow allocators to take the lock
704 }
705
706 if (count > 0) {
707 control_thread()->notify_heap_changed();
708 }
709 }
710
711 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
712 // New object should fit the GCLAB size
713 size_t min_size = MAX2(size, PLAB::min_size());
714
715 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
716 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
717 new_size = MIN2(new_size, PLAB::max_size());
718 new_size = MAX2(new_size, PLAB::min_size());
719
720 // Record new heuristic value even if we take any shortcut. This captures
721 // the case when moderately-sized objects always take a shortcut. At some point,
722 // heuristics should catch up with them.
723 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
724
725 if (new_size < size) {
726 // New size still does not fit the object. Fall back to shared allocation.
727 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
728 return NULL;
729 }
730
731 // Retire current GCLAB, and allocate a new one.
732 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
733 gclab->retire();
734
735 size_t actual_size = 0;
736 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
737 if (gclab_buf == NULL) {
738 return NULL;
739 }
740
741 assert (size <= actual_size, "allocation should fit");
742
743 if (ZeroTLAB) {
744 // ..and clear it.
745 Copy::zero_to_words(gclab_buf, actual_size);
746 } else {
747 // ...and zap just allocated object.
748 #ifdef ASSERT
749 // Skip mangling the space corresponding to the object header to
750 // ensure that the returned space is not considered parsable by
751 // any concurrent GC thread.
752 size_t hdr_size = oopDesc::header_size();
753 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
754 #endif // ASSERT
755 }
756 gclab->set_buf(gclab_buf, actual_size);
757 return gclab->allocate(size);
758 }
759
760 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
761 size_t requested_size,
762 size_t* actual_size) {
763 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
764 HeapWord* res = allocate_memory(req);
765 if (res != NULL) {
766 *actual_size = req.actual_size();
767 } else {
768 *actual_size = 0;
769 }
770 return res;
771 }
772
773 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
774 size_t word_size,
775 size_t* actual_size) {
776 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
777 HeapWord* res = allocate_memory(req);
778 if (res != NULL) {
779 *actual_size = req.actual_size();
780 } else {
781 *actual_size = 0;
782 }
783 return res;
784 }
785
786 ShenandoahHeap* ShenandoahHeap::heap() {
787 CollectedHeap* heap = Universe::heap();
788 assert(heap != NULL, "Unitialized access to ShenandoahHeap::heap()");
789 assert(heap->kind() == CollectedHeap::Shenandoah, "not a shenandoah heap");
790 return (ShenandoahHeap*) heap;
791 }
792
793 ShenandoahHeap* ShenandoahHeap::heap_no_check() {
794 CollectedHeap* heap = Universe::heap();
795 return (ShenandoahHeap*) heap;
796 }
797
798 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
799 ShenandoahAllocTrace trace_alloc(req.size(), req.type());
800
801 intptr_t pacer_epoch = 0;
802 bool in_new_region = false;
803 HeapWord* result = NULL;
804
805 if (req.is_mutator_alloc()) {
806 if (ShenandoahPacing) {
807 pacer()->pace_for_alloc(req.size());
808 pacer_epoch = pacer()->epoch();
809 }
810
811 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
812 result = allocate_memory_under_lock(req, in_new_region);
813 }
814
815 // Allocation failed, block until control thread reacted, then retry allocation.
816 //
817 // It might happen that one of the threads requesting allocation would unblock
818 // way later after GC happened, only to fail the second allocation, because
819 // other threads have already depleted the free storage. In this case, a better
820 // strategy is to try again, as long as GC makes progress.
821 //
822 // Then, we need to make sure the allocation was retried after at least one
823 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
824
825 size_t tries = 0;
826
827 while (result == NULL && _progress_last_gc.is_set()) {
828 tries++;
829 control_thread()->handle_alloc_failure(req.size());
830 result = allocate_memory_under_lock(req, in_new_region);
831 }
832
833 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
834 tries++;
835 control_thread()->handle_alloc_failure(req.size());
836 result = allocate_memory_under_lock(req, in_new_region);
837 }
838
839 } else {
840 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
841 result = allocate_memory_under_lock(req, in_new_region);
842 // Do not call handle_alloc_failure() here, because we cannot block.
843 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
844 }
845
846 if (in_new_region) {
847 control_thread()->notify_heap_changed();
848 }
849
850 if (result != NULL) {
851 size_t requested = req.size();
852 size_t actual = req.actual_size();
853
854 assert (req.is_lab_alloc() || (requested == actual),
855 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
856 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
857
858 if (req.is_mutator_alloc()) {
859 notify_mutator_alloc_words(actual, false);
860
861 // If we requested more than we were granted, give the rest back to pacer.
862 // This only matters if we are in the same pacing epoch: do not try to unpace
863 // over the budget for the other phase.
864 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
865 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
866 }
867 } else {
868 increase_used(actual*HeapWordSize);
869 }
870 }
871
872 return result;
873 }
874
875 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
876 ShenandoahHeapLocker locker(lock());
877 return _free_set->allocate(req, in_new_region);
878 }
879
880 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
881 bool* gc_overhead_limit_was_exceeded) {
882 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
883 return allocate_memory(req);
884 }
885
886 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
887 size_t size,
888 Metaspace::MetadataType mdtype) {
889 MetaWord* result;
890
891 // Inform metaspace OOM to GC heuristics if class unloading is possible.
892 if (heuristics()->can_unload_classes()) {
893 ShenandoahHeuristics* h = heuristics();
894 h->record_metaspace_oom();
895 }
896
897 // Expand and retry allocation
898 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
899 if (result != NULL) {
900 return result;
901 }
902
903 // Start full GC
904 collect(GCCause::_metadata_GC_clear_soft_refs);
905
906 // Retry allocation
907 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
908 if (result != NULL) {
909 return result;
910 }
911
912 // Expand and retry allocation
913 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
914 if (result != NULL) {
915 return result;
916 }
917
918 // Out of memory
919 return NULL;
920 }
921
922 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
923 private:
924 ShenandoahHeap* const _heap;
925 Thread* const _thread;
926 public:
927 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
928 _heap(heap), _thread(Thread::current()) {}
929
930 void do_object(oop p) {
931 shenandoah_assert_marked(NULL, p);
932 if (!p->is_forwarded()) {
933 _heap->evacuate_object(p, _thread);
934 }
935 }
936 };
937
938 class ShenandoahEvacuationTask : public AbstractGangTask {
939 private:
940 ShenandoahHeap* const _sh;
941 ShenandoahCollectionSet* const _cs;
942 bool _concurrent;
943 public:
944 ShenandoahEvacuationTask(ShenandoahHeap* sh,
945 ShenandoahCollectionSet* cs,
946 bool concurrent) :
947 AbstractGangTask("Parallel Evacuation Task"),
948 _sh(sh),
949 _cs(cs),
950 _concurrent(concurrent)
951 {}
952
953 void work(uint worker_id) {
954 if (_concurrent) {
955 ShenandoahConcurrentWorkerSession worker_session(worker_id);
956 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
957 ShenandoahEvacOOMScope oom_evac_scope;
958 do_work();
959 } else {
960 ShenandoahParallelWorkerSession worker_session(worker_id);
961 ShenandoahEvacOOMScope oom_evac_scope;
962 do_work();
963 }
964 }
965
966 private:
967 void do_work() {
968 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
969 ShenandoahHeapRegion* r;
970 while ((r =_cs->claim_next()) != NULL) {
971 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->region_number());
972 _sh->marked_object_iterate(r, &cl);
973
974 if (ShenandoahPacing) {
975 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
976 }
977
978 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
979 break;
980 }
981 }
982 }
983 };
984
985 void ShenandoahHeap::trash_cset_regions() {
986 ShenandoahHeapLocker locker(lock());
987
988 ShenandoahCollectionSet* set = collection_set();
989 ShenandoahHeapRegion* r;
990 set->clear_current_index();
991 while ((r = set->next()) != NULL) {
992 r->make_trash();
993 }
994 collection_set()->clear();
995 }
996
997 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
998 st->print_cr("Heap Regions:");
999 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
1000 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
1001 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start (previous, next)");
1002 st->print_cr("SN=alloc sequence numbers (first mutator, last mutator, first gc, last gc)");
1003
1004 for (size_t i = 0; i < num_regions(); i++) {
1005 get_region(i)->print_on(st);
1006 }
1007 }
1008
1009 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1010 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1011
1012 oop humongous_obj = oop(start->bottom());
1013 size_t size = humongous_obj->size();
1014 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1015 size_t index = start->region_number() + required_regions - 1;
1016
1017 assert(!start->has_live(), "liveness must be zero");
1018
1019 for(size_t i = 0; i < required_regions; i++) {
1020 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1021 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1022 ShenandoahHeapRegion* region = get_region(index --);
1023
1024 assert(region->is_humongous(), "expect correct humongous start or continuation");
1025 assert(!region->is_cset(), "Humongous region should not be in collection set");
1026
1027 region->make_trash_immediate();
1028 }
1029 }
1030
1031 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1032 public:
1033 void do_thread(Thread* thread) {
1034 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1035 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1036 gclab->retire();
1037 }
1038 };
1039
1040 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
1041 if (UseTLAB) {
1042 CollectedHeap::ensure_parsability(retire_tlabs);
1043 }
1044 ShenandoahRetireGCLABClosure cl;
1045 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1046 cl.do_thread(t);
1047 }
1048 workers()->threads_do(&cl);
1049 }
1050
1051 void ShenandoahHeap::resize_tlabs() {
1052 CollectedHeap::resize_all_tlabs();
1053 }
1054
1055 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1056 private:
1057 ShenandoahRootEvacuator* _rp;
1058
1059 public:
1060 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1061 AbstractGangTask("Shenandoah evacuate and update roots"),
1062 _rp(rp) {}
1063
1064 void work(uint worker_id) {
1065 ShenandoahParallelWorkerSession worker_session(worker_id);
1066 ShenandoahEvacOOMScope oom_evac_scope;
1067 ShenandoahEvacuateUpdateRootsClosure cl;
1068 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1069 _rp->roots_do(worker_id, &cl);
1070 }
1071 };
1072
1073 void ShenandoahHeap::evacuate_and_update_roots() {
1074 #if COMPILER2_OR_JVMCI
1075 DerivedPointerTable::clear();
1076 #endif
1077 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1078 {
1079 // Include concurrent roots if current cycle can not process those roots concurrently
1080 ShenandoahRootEvacuator rp(workers()->active_workers(),
1081 ShenandoahPhaseTimings::init_evac,
1082 !ShenandoahConcurrentRoots::should_do_concurrent_roots(),
1083 !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
1084 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1085 workers()->run_task(&roots_task);
1086 }
1087
1088 #if COMPILER2_OR_JVMCI
1089 DerivedPointerTable::update_pointers();
1090 #endif
1091 }
1092
1093 // Returns size in bytes
1094 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1095 if (ShenandoahElasticTLAB) {
1096 // With Elastic TLABs, return the max allowed size, and let the allocation path
1097 // figure out the safe size for current allocation.
1098 return ShenandoahHeapRegion::max_tlab_size_bytes();
1099 } else {
1100 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1101 }
1102 }
1103
1104 size_t ShenandoahHeap::max_tlab_size() const {
1105 // Returns size in words
1106 return ShenandoahHeapRegion::max_tlab_size_words();
1107 }
1108
1109 class ShenandoahRetireAndResetGCLABClosure : public ThreadClosure {
1110 public:
1111 void do_thread(Thread* thread) {
1112 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1113 gclab->retire();
1114 if (ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1115 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1116 }
1117 }
1118 };
1119
1120 void ShenandoahHeap::retire_and_reset_gclabs() {
1121 ShenandoahRetireAndResetGCLABClosure cl;
1122 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1123 cl.do_thread(t);
1124 }
1125 workers()->threads_do(&cl);
1126 }
1127
1128 void ShenandoahHeap::collect(GCCause::Cause cause) {
1129 control_thread()->request_gc(cause);
1130 }
1131
1132 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1133 //assert(false, "Shouldn't need to do full collections");
1134 }
1135
1136 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1137 Space* sp = heap_region_containing(addr);
1138 if (sp != NULL) {
1139 return sp->block_start(addr);
1140 }
1141 return NULL;
1142 }
1143
1144 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1145 Space* sp = heap_region_containing(addr);
1146 return sp->block_is_obj(addr);
1147 }
1148
1149 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1150 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1151 }
1152
1153 jlong ShenandoahHeap::millis_since_last_gc() {
1154 double v = heuristics()->time_since_last_gc() * 1000;
1155 assert(0 <= v && v <= max_jlong, "value should fit: %f", v);
1156 return (jlong)v;
1157 }
1158
1159 void ShenandoahHeap::prepare_for_verify() {
1160 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1161 make_parsable(false);
1162 }
1163 }
1164
1165 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1166 workers()->print_worker_threads_on(st);
1167 if (ShenandoahStringDedup::is_enabled()) {
1168 ShenandoahStringDedup::print_worker_threads_on(st);
1169 }
1170 }
1171
1172 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1173 workers()->threads_do(tcl);
1174 if (_safepoint_workers != NULL) {
1175 _safepoint_workers->threads_do(tcl);
1176 }
1177 if (ShenandoahStringDedup::is_enabled()) {
1178 ShenandoahStringDedup::threads_do(tcl);
1179 }
1180 }
1181
1182 void ShenandoahHeap::print_tracing_info() const {
1183 LogTarget(Info, gc, stats) lt;
1184 if (lt.is_enabled()) {
1185 ResourceMark rm;
1186 LogStream ls(lt);
1187
1188 phase_timings()->print_on(&ls);
1189
1190 ls.cr();
1191 ls.cr();
1192
1193 shenandoah_policy()->print_gc_stats(&ls);
1194
1195 ls.cr();
1196 ls.cr();
1197
1198 if (ShenandoahPacing) {
1199 pacer()->print_on(&ls);
1200 }
1201
1202 ls.cr();
1203 ls.cr();
1204
1205 if (ShenandoahAllocationTrace) {
1206 assert(alloc_tracker() != NULL, "Must be");
1207 alloc_tracker()->print_on(&ls);
1208 } else {
1209 ls.print_cr(" Allocation tracing is disabled, use -XX:+ShenandoahAllocationTrace to enable.");
1210 }
1211 }
1212 }
1213
1214 void ShenandoahHeap::verify(VerifyOption vo) {
1215 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1216 if (ShenandoahVerify) {
1217 verifier()->verify_generic(vo);
1218 } else {
1219 // TODO: Consider allocating verification bitmaps on demand,
1220 // and turn this on unconditionally.
1221 }
1222 }
1223 }
1224 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1225 return _free_set->capacity();
1226 }
1227
1228 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1229 private:
1230 MarkBitMap* _bitmap;
1231 Stack<oop,mtGC>* _oop_stack;
1232
1233 template <class T>
1234 void do_oop_work(T* p) {
1235 T o = RawAccess<>::oop_load(p);
1236 if (!CompressedOops::is_null(o)) {
1237 oop obj = CompressedOops::decode_not_null(o);
1238 oop fwd = (oop) ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
1239 if (fwd == NULL) {
1240 // There is an odd interaction with VM_HeapWalkOperation, see jvmtiTagMap.cpp.
1241 //
1242 // That operation walks the reachable objects on its own, storing the marking
1243 // wavefront in the object marks. When it is done, it calls the CollectedHeap
1244 // to iterate over all objects to clean up the mess. When it reaches here,
1245 // the Shenandoah fwdptr resolution code encounters the marked objects with
1246 // NULL forwardee. Trying to act on that would crash the VM. Or fail the
1247 // asserts, should we go for resolve_forwarded_pointer(obj).
1248 //
1249 // Therefore, we have to dodge it by doing the raw access to forwardee, and
1250 // assuming the object had no forwardee, if that thing is NULL.
1251 } else {
1252 obj = fwd;
1253 }
1254 assert(oopDesc::is_oop(obj), "must be a valid oop");
1255 if (!_bitmap->is_marked((HeapWord*) obj)) {
1256 _bitmap->mark((HeapWord*) obj);
1257 _oop_stack->push(obj);
1258 }
1259 }
1260 }
1261 public:
1262 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1263 _bitmap(bitmap), _oop_stack(oop_stack) {}
1264 void do_oop(oop* p) { do_oop_work(p); }
1265 void do_oop(narrowOop* p) { do_oop_work(p); }
1266 };
1267
1268 /*
1269 * This is public API, used in preparation of object_iterate().
1270 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1271 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1272 * control, we call SH::make_tlabs_parsable().
1273 */
1274 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1275 // No-op.
1276 }
1277
1278 /*
1279 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1280 *
1281 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1282 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1283 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1284 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1285 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1286 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1287 * wiped the bitmap in preparation for next marking).
1288 *
1289 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1290 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1291 * is allowed to report dead objects, but is not required to do so.
1292 */
1293 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1294 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1295 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1296 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1297 return;
1298 }
1299
1300 // Reset bitmap
1301 _aux_bit_map.clear();
1302
1303 Stack<oop,mtGC> oop_stack;
1304
1305 // First, we process GC roots according to current GC cycle. This populates the work stack with initial objects.
1306 ShenandoahHeapIterationRootScanner rp;
1307 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1308
1309 // If we are unloading classes right now, we should not touch weak roots,
1310 // on the off-chance we would evacuate them and make them live accidentally.
1311 // In other cases, we have to scan all roots.
1312 if (is_evacuation_in_progress() && unload_classes()) {
1313 rp.strong_roots_do(&oops);
1314 } else {
1315 rp.roots_do(&oops);
1316 }
1317
1318 // Work through the oop stack to traverse heap.
1319 while (! oop_stack.is_empty()) {
1320 oop obj = oop_stack.pop();
1321 assert(oopDesc::is_oop(obj), "must be a valid oop");
1322 cl->do_object(obj);
1323 obj->oop_iterate(&oops);
1324 }
1325
1326 assert(oop_stack.is_empty(), "should be empty");
1327
1328 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1329 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1330 }
1331 }
1332
1333 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1334 void ShenandoahHeap::keep_alive(oop obj) {
1335 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1336 }
1337
1338 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1339 for (size_t i = 0; i < num_regions(); i++) {
1340 ShenandoahHeapRegion* current = get_region(i);
1341 blk->heap_region_do(current);
1342 }
1343 }
1344
1345 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1346 private:
1347 ShenandoahHeap* const _heap;
1348 ShenandoahHeapRegionClosure* const _blk;
1349
1350 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));
1351 volatile size_t _index;
1352 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
1353
1354 public:
1355 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1356 AbstractGangTask("Parallel Region Task"),
1357 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1358
1359 void work(uint worker_id) {
1360 size_t stride = ShenandoahParallelRegionStride;
1361
1362 size_t max = _heap->num_regions();
1363 while (_index < max) {
1364 size_t cur = Atomic::add(&_index, stride) - stride;
1365 size_t start = cur;
1366 size_t end = MIN2(cur + stride, max);
1367 if (start >= max) break;
1368
1369 for (size_t i = cur; i < end; i++) {
1370 ShenandoahHeapRegion* current = _heap->get_region(i);
1371 _blk->heap_region_do(current);
1372 }
1373 }
1374 }
1375 };
1376
1377 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1378 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1379 if (num_regions() > ShenandoahParallelRegionStride) {
1380 ShenandoahParallelHeapRegionTask task(blk);
1381 workers()->run_task(&task);
1382 } else {
1383 heap_region_iterate(blk);
1384 }
1385 }
1386
1387 class ShenandoahClearLivenessClosure : public ShenandoahHeapRegionClosure {
1388 private:
1389 ShenandoahMarkingContext* const _ctx;
1390 public:
1391 ShenandoahClearLivenessClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1392
1393 void heap_region_do(ShenandoahHeapRegion* r) {
1394 if (r->is_active()) {
1395 r->clear_live_data();
1396 _ctx->capture_top_at_mark_start(r);
1397 } else {
1398 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1399 assert(_ctx->top_at_mark_start(r) == r->top(),
1400 "Region " SIZE_FORMAT " should already have correct TAMS", r->region_number());
1401 }
1402 }
1403
1404 bool is_thread_safe() { return true; }
1405 };
1406
1407 void ShenandoahHeap::op_init_mark() {
1408 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1409 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1410
1411 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1412 assert(!marking_context()->is_complete(), "should not be complete");
1413
1414 if (ShenandoahVerify) {
1415 verifier()->verify_before_concmark();
1416 }
1417
1418 if (VerifyBeforeGC) {
1419 Universe::verify();
1420 }
1421
1422 set_concurrent_mark_in_progress(true);
1423 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1424 {
1425 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1426 make_parsable(true);
1427 }
1428
1429 {
1430 ShenandoahGCPhase phase(ShenandoahPhaseTimings::clear_liveness);
1431 ShenandoahClearLivenessClosure clc;
1432 parallel_heap_region_iterate(&clc);
1433 }
1434
1435 // Make above changes visible to worker threads
1436 OrderAccess::fence();
1437
1438 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1439
1440 if (UseTLAB) {
1441 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1442 resize_tlabs();
1443 }
1444
1445 if (ShenandoahPacing) {
1446 pacer()->setup_for_mark();
1447 }
1448 }
1449
1450 void ShenandoahHeap::op_mark() {
1451 concurrent_mark()->mark_from_roots();
1452 }
1453
1454 class ShenandoahCompleteLivenessClosure : public ShenandoahHeapRegionClosure {
1455 private:
1456 ShenandoahMarkingContext* const _ctx;
1457 public:
1458 ShenandoahCompleteLivenessClosure() : _ctx(ShenandoahHeap::heap()->complete_marking_context()) {}
1459
1460 void heap_region_do(ShenandoahHeapRegion* r) {
1461 if (r->is_active()) {
1462 HeapWord *tams = _ctx->top_at_mark_start(r);
1463 HeapWord *top = r->top();
1464 if (top > tams) {
1465 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1466 }
1467 } else {
1468 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1469 assert(_ctx->top_at_mark_start(r) == r->top(),
1470 "Region " SIZE_FORMAT " should have correct TAMS", r->region_number());
1471 }
1472 }
1473
1474 bool is_thread_safe() { return true; }
1475 };
1476
1477 void ShenandoahHeap::op_final_mark() {
1478 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1479
1480 // It is critical that we
1481 // evacuate roots right after finishing marking, so that we don't
1482 // get unmarked objects in the roots.
1483
1484 if (!cancelled_gc()) {
1485 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1486
1487 // Marking is completed, deactivate SATB barrier
1488 set_concurrent_mark_in_progress(false);
1489 mark_complete_marking_context();
1490
1491 parallel_cleaning(false /* full gc*/);
1492
1493 if (has_forwarded_objects()) {
1494 // Degen may be caused by failed evacuation of roots
1495 if (is_degenerated_gc_in_progress()) {
1496 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
1497 } else {
1498 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::update_roots);
1499 }
1500 set_has_forwarded_objects(false);
1501 }
1502
1503 if (ShenandoahVerify) {
1504 verifier()->verify_roots_no_forwarded();
1505 }
1506 // All allocations past TAMS are implicitly live, adjust the region data.
1507 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1508 {
1509 ShenandoahGCPhase phase(ShenandoahPhaseTimings::complete_liveness);
1510 ShenandoahCompleteLivenessClosure cl;
1511 parallel_heap_region_iterate(&cl);
1512 }
1513
1514 // Force the threads to reacquire their TLABs outside the collection set.
1515 {
1516 ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs);
1517 make_parsable(true);
1518 }
1519
1520 // We are about to select the collection set, make sure it knows about
1521 // current pinning status. Also, this allows trashing more regions that
1522 // now have their pinning status dropped.
1523 {
1524 ShenandoahGCPhase phase(ShenandoahPhaseTimings::sync_pinned);
1525 sync_pinned_region_status();
1526 }
1527
1528 // Trash the collection set left over from previous cycle, if any.
1529 {
1530 ShenandoahGCPhase phase(ShenandoahPhaseTimings::trash_cset);
1531 trash_cset_regions();
1532 }
1533
1534 {
1535 ShenandoahGCPhase phase(ShenandoahPhaseTimings::prepare_evac);
1536
1537 ShenandoahHeapLocker locker(lock());
1538 _collection_set->clear();
1539 _free_set->clear();
1540
1541 heuristics()->choose_collection_set(_collection_set);
1542
1543 _free_set->rebuild();
1544 }
1545
1546 if (!is_degenerated_gc_in_progress()) {
1547 prepare_concurrent_roots();
1548 prepare_concurrent_unloading();
1549 }
1550
1551 // If collection set has candidates, start evacuation.
1552 // Otherwise, bypass the rest of the cycle.
1553 if (!collection_set()->is_empty()) {
1554 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1555
1556 if (ShenandoahVerify) {
1557 verifier()->verify_before_evacuation();
1558 }
1559
1560 set_evacuation_in_progress(true);
1561 // From here on, we need to update references.
1562 set_has_forwarded_objects(true);
1563
1564 if (!is_degenerated_gc_in_progress()) {
1565 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1566 ShenandoahCodeRoots::arm_nmethods();
1567 }
1568 evacuate_and_update_roots();
1569 }
1570
1571 if (ShenandoahPacing) {
1572 pacer()->setup_for_evac();
1573 }
1574
1575 if (ShenandoahVerify) {
1576 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::None;
1577 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1578 types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots);
1579 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots);
1580 }
1581
1582 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1583 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CodeRoots);
1584 }
1585 verifier()->verify_roots_no_forwarded_except(types);
1586 verifier()->verify_during_evacuation();
1587 }
1588 } else {
1589 if (ShenandoahVerify) {
1590 verifier()->verify_after_concmark();
1591 }
1592
1593 if (VerifyAfterGC) {
1594 Universe::verify();
1595 }
1596 }
1597
1598 } else {
1599 // If this cycle was updating references, we need to keep the has_forwarded_objects
1600 // flag on, for subsequent phases to deal with it.
1601 concurrent_mark()->cancel();
1602 set_concurrent_mark_in_progress(false);
1603
1604 if (process_references()) {
1605 // Abandon reference processing right away: pre-cleaning must have failed.
1606 ReferenceProcessor *rp = ref_processor();
1607 rp->disable_discovery();
1608 rp->abandon_partial_discovery();
1609 rp->verify_no_references_recorded();
1610 }
1611 }
1612 }
1613
1614 void ShenandoahHeap::op_final_evac() {
1615 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1616
1617 set_evacuation_in_progress(false);
1618
1619 {
1620 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_retire_gclabs);
1621 retire_and_reset_gclabs();
1622 }
1623
1624 if (ShenandoahVerify) {
1625 verifier()->verify_after_evacuation();
1626 }
1627
1628 if (VerifyAfterGC) {
1629 Universe::verify();
1630 }
1631 }
1632
1633 void ShenandoahHeap::op_conc_evac() {
1634 ShenandoahEvacuationTask task(this, _collection_set, true);
1635 workers()->run_task(&task);
1636 }
1637
1638 void ShenandoahHeap::op_stw_evac() {
1639 ShenandoahEvacuationTask task(this, _collection_set, false);
1640 workers()->run_task(&task);
1641 }
1642
1643 void ShenandoahHeap::op_updaterefs() {
1644 update_heap_references(true);
1645 }
1646
1647 void ShenandoahHeap::op_cleanup() {
1648 free_set()->recycle_trash();
1649 }
1650
1651 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask {
1652 private:
1653 ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
1654 ShenandoahWeakRoots<true /*concurrent*/> _weak_roots;
1655 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots;
1656 bool _include_weak_roots;
1657
1658 public:
1659 ShenandoahConcurrentRootsEvacUpdateTask(bool include_weak_roots) :
1660 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Roots Task"),
1661 _include_weak_roots(include_weak_roots) {
1662 }
1663
1664 void work(uint worker_id) {
1665 ShenandoahEvacOOMScope oom;
1666 {
1667 // vm_roots and weak_roots are OopStorage backed roots, concurrent iteration
1668 // may race against OopStorage::release() calls.
1669 ShenandoahEvacUpdateOopStorageRootsClosure cl;
1670 _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1671
1672 if (_include_weak_roots) {
1673 _weak_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1674 }
1675 }
1676
1677 {
1678 ShenandoahEvacuateUpdateRootsClosure cl;
1679 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1680 _cld_roots.cld_do(&clds);
1681 }
1682 }
1683 };
1684
1685 class ShenandoahEvacUpdateCleanupOopStorageRootsClosure : public BasicOopIterateClosure {
1686 private:
1687 ShenandoahHeap* const _heap;
1688 ShenandoahMarkingContext* const _mark_context;
1689 bool _evac_in_progress;
1690 Thread* const _thread;
1691 size_t _dead_counter;
1692
1693 public:
1694 ShenandoahEvacUpdateCleanupOopStorageRootsClosure();
1695 void do_oop(oop* p);
1696 void do_oop(narrowOop* p);
1697
1698 size_t dead_counter() const;
1699 void reset_dead_counter();
1700 };
1701
1702 ShenandoahEvacUpdateCleanupOopStorageRootsClosure::ShenandoahEvacUpdateCleanupOopStorageRootsClosure() :
1703 _heap(ShenandoahHeap::heap()),
1704 _mark_context(ShenandoahHeap::heap()->marking_context()),
1705 _evac_in_progress(ShenandoahHeap::heap()->is_evacuation_in_progress()),
1706 _thread(Thread::current()),
1707 _dead_counter(0) {
1708 }
1709
1710 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(oop* p) {
1711 const oop obj = RawAccess<>::oop_load(p);
1712 if (!CompressedOops::is_null(obj)) {
1713 if (!_mark_context->is_marked(obj)) {
1714 shenandoah_assert_correct(p, obj);
1715 oop old = Atomic::cmpxchg(p, obj, oop(NULL));
1716 if (obj == old) {
1717 _dead_counter ++;
1718 }
1719 } else if (_evac_in_progress && _heap->in_collection_set(obj)) {
1720 oop resolved = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1721 if (resolved == obj) {
1722 resolved = _heap->evacuate_object(obj, _thread);
1723 }
1724 Atomic::cmpxchg(p, obj, resolved);
1725 assert(_heap->cancelled_gc() ||
1726 _mark_context->is_marked(resolved) && !_heap->in_collection_set(resolved),
1727 "Sanity");
1728 }
1729 }
1730 }
1731
1732 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(narrowOop* p) {
1733 ShouldNotReachHere();
1734 }
1735
1736 size_t ShenandoahEvacUpdateCleanupOopStorageRootsClosure::dead_counter() const {
1737 return _dead_counter;
1738 }
1739
1740 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::reset_dead_counter() {
1741 _dead_counter = 0;
1742 }
1743
1744 // This task not only evacuates/updates marked weak roots, but also "NULL"
1745 // dead weak roots.
1746 class ShenandoahConcurrentWeakRootsEvacUpdateTask : public AbstractGangTask {
1747 private:
1748 ShenandoahWeakRoot<true /*concurrent*/> _jni_roots;
1749 ShenandoahWeakRoot<true /*concurrent*/> _string_table_roots;
1750 ShenandoahWeakRoot<true /*concurrent*/> _resolved_method_table_roots;
1751 ShenandoahWeakRoot<true /*concurrent*/> _vm_roots;
1752
1753 public:
1754 ShenandoahConcurrentWeakRootsEvacUpdateTask() :
1755 AbstractGangTask("Shenandoah Concurrent Weak Root Task"),
1756 _jni_roots(OopStorageSet::jni_weak(), ShenandoahPhaseTimings::JNIWeakRoots),
1757 _string_table_roots(OopStorageSet::string_table_weak(), ShenandoahPhaseTimings::StringTableRoots),
1758 _resolved_method_table_roots(OopStorageSet::resolved_method_table_weak(), ShenandoahPhaseTimings::ResolvedMethodTableRoots),
1759 _vm_roots(OopStorageSet::vm_weak(), ShenandoahPhaseTimings::VMWeakRoots) {
1760 StringTable::reset_dead_counter();
1761 ResolvedMethodTable::reset_dead_counter();
1762 }
1763
1764 ~ShenandoahConcurrentWeakRootsEvacUpdateTask() {
1765 StringTable::finish_dead_counter();
1766 ResolvedMethodTable::finish_dead_counter();
1767 }
1768
1769 void work(uint worker_id) {
1770 ShenandoahEvacOOMScope oom;
1771 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
1772 // may race against OopStorage::release() calls.
1773 ShenandoahEvacUpdateCleanupOopStorageRootsClosure cl;
1774 _jni_roots.oops_do(&cl, worker_id);
1775 _vm_roots.oops_do(&cl, worker_id);
1776
1777 cl.reset_dead_counter();
1778 _string_table_roots.oops_do(&cl, worker_id);
1779 StringTable::inc_dead_counter(cl.dead_counter());
1780
1781 cl.reset_dead_counter();
1782 _resolved_method_table_roots.oops_do(&cl, worker_id);
1783 ResolvedMethodTable::inc_dead_counter(cl.dead_counter());
1784 }
1785 };
1786
1787 void ShenandoahHeap::op_roots() {
1788 if (is_concurrent_root_in_progress()) {
1789 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1790 // Concurrent weak root processing
1791 ShenandoahConcurrentWeakRootsEvacUpdateTask task;
1792 workers()->run_task(&task);
1793
1794 _unloader.unload();
1795 }
1796
1797 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1798 ShenandoahConcurrentRootsEvacUpdateTask task(!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
1799 workers()->run_task(&task);
1800 }
1801 }
1802
1803 set_concurrent_root_in_progress(false);
1804 }
1805
1806 void ShenandoahHeap::op_reset() {
1807 reset_mark_bitmap();
1808 }
1809
1810 void ShenandoahHeap::op_preclean() {
1811 concurrent_mark()->preclean_weak_refs();
1812 }
1813
1814 void ShenandoahHeap::op_init_traversal() {
1815 traversal_gc()->init_traversal_collection();
1816 }
1817
1818 void ShenandoahHeap::op_traversal() {
1819 traversal_gc()->concurrent_traversal_collection();
1820 }
1821
1822 void ShenandoahHeap::op_final_traversal() {
1823 traversal_gc()->final_traversal_collection();
1824 }
1825
1826 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1827 ShenandoahMetricsSnapshot metrics;
1828 metrics.snap_before();
1829
1830 full_gc()->do_it(cause);
1831 if (UseTLAB) {
1832 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs);
1833 resize_all_tlabs();
1834 }
1835
1836 metrics.snap_after();
1837
1838 if (metrics.is_good_progress()) {
1839 _progress_last_gc.set();
1840 } else {
1841 // Nothing to do. Tell the allocation path that we have failed to make
1842 // progress, and it can finally fail.
1843 _progress_last_gc.unset();
1844 }
1845 }
1846
1847 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1848 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1849 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1850 // some phase, we have to upgrade the Degenerate GC to Full GC.
1851
1852 clear_cancelled_gc();
1853
1854 ShenandoahMetricsSnapshot metrics;
1855 metrics.snap_before();
1856
1857 switch (point) {
1858 case _degenerated_traversal:
1859 {
1860 // Drop the collection set. Note: this leaves some already forwarded objects
1861 // behind, which may be problematic, see comments for ShenandoahEvacAssist
1862 // workarounds in ShenandoahTraversalHeuristics.
1863
1864 ShenandoahHeapLocker locker(lock());
1865 collection_set()->clear_current_index();
1866 for (size_t i = 0; i < collection_set()->count(); i++) {
1867 ShenandoahHeapRegion* r = collection_set()->next();
1868 r->make_regular_bypass();
1869 }
1870 collection_set()->clear();
1871 }
1872 op_final_traversal();
1873 op_cleanup();
1874 return;
1875
1876 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1877 // but enters it at different points, depending on which concurrent phase had
1878 // degenerated.
1879
1880 case _degenerated_outside_cycle:
1881 // We have degenerated from outside the cycle, which means something is bad with
1882 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1883 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1884 // we can do the most aggressive degen cycle, which includes processing references and
1885 // class unloading, unless those features are explicitly disabled.
1886 //
1887 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1888 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1889 set_process_references(heuristics()->can_process_references());
1890 set_unload_classes(heuristics()->can_unload_classes());
1891
1892 if (is_traversal_mode()) {
1893 // Not possible to degenerate from here, upgrade to Full GC right away.
1894 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1895 op_degenerated_fail();
1896 return;
1897 }
1898
1899 op_reset();
1900
1901 op_init_mark();
1902 if (cancelled_gc()) {
1903 op_degenerated_fail();
1904 return;
1905 }
1906
1907 case _degenerated_mark:
1908 op_final_mark();
1909 if (cancelled_gc()) {
1910 op_degenerated_fail();
1911 return;
1912 }
1913
1914 op_cleanup();
1915
1916 case _degenerated_evac:
1917 // If heuristics thinks we should do the cycle, this flag would be set,
1918 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
1919 if (is_evacuation_in_progress()) {
1920
1921 // Degeneration under oom-evac protocol might have left some objects in
1922 // collection set un-evacuated. Restart evacuation from the beginning to
1923 // capture all objects. For all the objects that are already evacuated,
1924 // it would be a simple check, which is supposed to be fast. This is also
1925 // safe to do even without degeneration, as CSet iterator is at beginning
1926 // in preparation for evacuation anyway.
1927 //
1928 // Before doing that, we need to make sure we never had any cset-pinned
1929 // regions. This may happen if allocation failure happened when evacuating
1930 // the about-to-be-pinned object, oom-evac protocol left the object in
1931 // the collection set, and then the pin reached the cset region. If we continue
1932 // the cycle here, we would trash the cset and alive objects in it. To avoid
1933 // it, we fail degeneration right away and slide into Full GC to recover.
1934
1935 {
1936 sync_pinned_region_status();
1937 collection_set()->clear_current_index();
1938
1939 ShenandoahHeapRegion* r;
1940 while ((r = collection_set()->next()) != NULL) {
1941 if (r->is_pinned()) {
1942 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1943 op_degenerated_fail();
1944 return;
1945 }
1946 }
1947
1948 collection_set()->clear_current_index();
1949 }
1950
1951 op_stw_evac();
1952 if (cancelled_gc()) {
1953 op_degenerated_fail();
1954 return;
1955 }
1956 }
1957
1958 // If heuristics thinks we should do the cycle, this flag would be set,
1959 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
1960 if (has_forwarded_objects()) {
1961 op_init_updaterefs();
1962 if (cancelled_gc()) {
1963 op_degenerated_fail();
1964 return;
1965 }
1966 }
1967
1968 case _degenerated_updaterefs:
1969 if (has_forwarded_objects()) {
1970 op_final_updaterefs();
1971 if (cancelled_gc()) {
1972 op_degenerated_fail();
1973 return;
1974 }
1975 }
1976
1977 op_cleanup();
1978 break;
1979
1980 default:
1981 ShouldNotReachHere();
1982 }
1983
1984 if (ShenandoahVerify) {
1985 verifier()->verify_after_degenerated();
1986 }
1987
1988 if (VerifyAfterGC) {
1989 Universe::verify();
1990 }
1991
1992 metrics.snap_after();
1993
1994 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
1995 // because that probably means the heap is overloaded and/or fragmented.
1996 if (!metrics.is_good_progress()) {
1997 _progress_last_gc.unset();
1998 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1999 op_degenerated_futile();
2000 } else {
2001 _progress_last_gc.set();
2002 }
2003 }
2004
2005 void ShenandoahHeap::op_degenerated_fail() {
2006 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
2007 shenandoah_policy()->record_degenerated_upgrade_to_full();
2008 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2009 }
2010
2011 void ShenandoahHeap::op_degenerated_futile() {
2012 shenandoah_policy()->record_degenerated_upgrade_to_full();
2013 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2014 }
2015
2016 void ShenandoahHeap::force_satb_flush_all_threads() {
2017 if (!is_concurrent_mark_in_progress() && !is_concurrent_traversal_in_progress()) {
2018 // No need to flush SATBs
2019 return;
2020 }
2021
2022 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2023 ShenandoahThreadLocalData::set_force_satb_flush(t, true);
2024 }
2025 // The threads are not "acquiring" their thread-local data, but it does not
2026 // hurt to "release" the updates here anyway.
2027 OrderAccess::fence();
2028 }
2029
2030 void ShenandoahHeap::set_gc_state_all_threads(char state) {
2031 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2032 ShenandoahThreadLocalData::set_gc_state(t, state);
2033 }
2034 }
2035
2036 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
2037 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
2038 _gc_state.set_cond(mask, value);
2039 set_gc_state_all_threads(_gc_state.raw_value());
2040 }
2041
2042 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
2043 if (has_forwarded_objects()) {
2044 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
2045 } else {
2046 set_gc_state_mask(MARKING, in_progress);
2047 }
2048 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
2049 }
2050
2051 void ShenandoahHeap::set_concurrent_traversal_in_progress(bool in_progress) {
2052 set_gc_state_mask(TRAVERSAL, in_progress);
2053 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
2054 }
2055
2056 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
2057 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
2058 set_gc_state_mask(EVACUATION, in_progress);
2059 }
2060
2061 void ShenandoahHeap::set_concurrent_root_in_progress(bool in_progress) {
2062 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
2063 if (in_progress) {
2064 _concurrent_root_in_progress.set();
2065 } else {
2066 _concurrent_root_in_progress.unset();
2067 }
2068 }
2069
2070 void ShenandoahHeap::ref_processing_init() {
2071 assert(_max_workers > 0, "Sanity");
2072
2073 _ref_processor =
2074 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
2075 ParallelRefProcEnabled, // MT processing
2076 _max_workers, // Degree of MT processing
2077 true, // MT discovery
2078 _max_workers, // Degree of MT discovery
2079 false, // Reference discovery is not atomic
2080 NULL, // No closure, should be installed before use
2081 true); // Scale worker threads
2082
2083 shenandoah_assert_rp_isalive_not_installed();
2084 }
2085
2086 GCTracer* ShenandoahHeap::tracer() {
2087 return shenandoah_policy()->tracer();
2088 }
2089
2090 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
2091 return _free_set->used();
2092 }
2093
2094 bool ShenandoahHeap::try_cancel_gc() {
2095 while (true) {
2096 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
2097 if (prev == CANCELLABLE) return true;
2098 else if (prev == CANCELLED) return false;
2099 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
2100 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
2101 if (Thread::current()->is_Java_thread()) {
2102 // We need to provide a safepoint here, otherwise we might
2103 // spin forever if a SP is pending.
2104 ThreadBlockInVM sp(JavaThread::current());
2105 SpinPause();
2106 }
2107 }
2108 }
2109
2110 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
2111 if (try_cancel_gc()) {
2112 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
2113 log_info(gc)("%s", msg.buffer());
2114 Events::log(Thread::current(), "%s", msg.buffer());
2115 }
2116 }
2117
2118 uint ShenandoahHeap::max_workers() {
2119 return _max_workers;
2120 }
2121
2122 void ShenandoahHeap::stop() {
2123 // The shutdown sequence should be able to terminate when GC is running.
2124
2125 // Step 0. Notify policy to disable event recording.
2126 _shenandoah_policy->record_shutdown();
2127
2128 // Step 1. Notify control thread that we are in shutdown.
2129 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
2130 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
2131 control_thread()->prepare_for_graceful_shutdown();
2132
2133 // Step 2. Notify GC workers that we are cancelling GC.
2134 cancel_gc(GCCause::_shenandoah_stop_vm);
2135
2136 // Step 3. Wait until GC worker exits normally.
2137 control_thread()->stop();
2138
2139 // Step 4. Stop String Dedup thread if it is active
2140 if (ShenandoahStringDedup::is_enabled()) {
2141 ShenandoahStringDedup::stop();
2142 }
2143 }
2144
2145 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
2146 if (!unload_classes()) return;
2147 bool purged_class;
2148
2149 // Unload classes and purge SystemDictionary.
2150 {
2151 ShenandoahGCPhase phase(full_gc ?
2152 ShenandoahPhaseTimings::full_gc_purge_class_unload :
2153 ShenandoahPhaseTimings::purge_class_unload);
2154 purged_class = SystemDictionary::do_unloading(gc_timer());
2155 }
2156
2157 {
2158 ShenandoahGCPhase phase(full_gc ?
2159 ShenandoahPhaseTimings::full_gc_purge_par :
2160 ShenandoahPhaseTimings::purge_par);
2161 ShenandoahIsAliveSelector is_alive;
2162 uint num_workers = _workers->active_workers();
2163 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
2164 _workers->run_task(&unlink_task);
2165 }
2166
2167 {
2168 ShenandoahGCPhase phase(full_gc ?
2169 ShenandoahPhaseTimings::full_gc_purge_cldg :
2170 ShenandoahPhaseTimings::purge_cldg);
2171 ClassLoaderDataGraph::purge();
2172 }
2173 // Resize and verify metaspace
2174 MetaspaceGC::compute_new_size();
2175 MetaspaceUtils::verify_metrics();
2176 }
2177
2178 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
2179 // so they should not have forwarded oops.
2180 // However, we do need to "null" dead oops in the roots, if can not be done
2181 // in concurrent cycles.
2182 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
2183 ShenandoahGCPhase root_phase(full_gc ?
2184 ShenandoahPhaseTimings::full_gc_purge :
2185 ShenandoahPhaseTimings::purge);
2186 uint num_workers = _workers->active_workers();
2187 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
2188 ShenandoahPhaseTimings::full_gc_purge_par :
2189 ShenandoahPhaseTimings::purge_par;
2190 // Cleanup weak roots
2191 ShenandoahGCPhase phase(timing_phase);
2192 phase_timings()->record_workers_start(timing_phase);
2193 if (has_forwarded_objects()) {
2194 if (is_traversal_mode()) {
2195 ShenandoahForwardedIsAliveClosure is_alive;
2196 ShenandoahTraversalUpdateRefsClosure keep_alive;
2197 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahTraversalUpdateRefsClosure>
2198 cleaning_task(&is_alive, &keep_alive, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2199 _workers->run_task(&cleaning_task);
2200 } else {
2201 ShenandoahForwardedIsAliveClosure is_alive;
2202 ShenandoahUpdateRefsClosure keep_alive;
2203 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2204 cleaning_task(&is_alive, &keep_alive, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2205 _workers->run_task(&cleaning_task);
2206 }
2207 } else {
2208 ShenandoahIsAliveClosure is_alive;
2209 #ifdef ASSERT
2210 ShenandoahAssertNotForwardedClosure verify_cl;
2211 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2212 cleaning_task(&is_alive, &verify_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2213 #else
2214 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2215 cleaning_task(&is_alive, &do_nothing_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2216 #endif
2217 _workers->run_task(&cleaning_task);
2218 }
2219 phase_timings()->record_workers_end(timing_phase);
2220 }
2221
2222 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2223 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2224 stw_process_weak_roots(full_gc);
2225 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2226 stw_unload_classes(full_gc);
2227 }
2228 }
2229
2230 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2231 if (is_traversal_mode()) {
2232 set_gc_state_mask(HAS_FORWARDED | UPDATEREFS, cond);
2233 } else {
2234 set_gc_state_mask(HAS_FORWARDED, cond);
2235 }
2236
2237 }
2238
2239 void ShenandoahHeap::set_process_references(bool pr) {
2240 _process_references.set_cond(pr);
2241 }
2242
2243 void ShenandoahHeap::set_unload_classes(bool uc) {
2244 _unload_classes.set_cond(uc);
2245 }
2246
2247 bool ShenandoahHeap::process_references() const {
2248 return _process_references.is_set();
2249 }
2250
2251 bool ShenandoahHeap::unload_classes() const {
2252 return _unload_classes.is_set();
2253 }
2254
2255 address ShenandoahHeap::in_cset_fast_test_addr() {
2256 ShenandoahHeap* heap = ShenandoahHeap::heap();
2257 assert(heap->collection_set() != NULL, "Sanity");
2258 return (address) heap->collection_set()->biased_map_address();
2259 }
2260
2261 address ShenandoahHeap::cancelled_gc_addr() {
2262 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
2263 }
2264
2265 address ShenandoahHeap::gc_state_addr() {
2266 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2267 }
2268
2269 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2270 return Atomic::load_acquire(&_bytes_allocated_since_gc_start);
2271 }
2272
2273 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2274 Atomic::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2275 }
2276
2277 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2278 _degenerated_gc_in_progress.set_cond(in_progress);
2279 }
2280
2281 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2282 _full_gc_in_progress.set_cond(in_progress);
2283 }
2284
2285 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2286 assert (is_full_gc_in_progress(), "should be");
2287 _full_gc_move_in_progress.set_cond(in_progress);
2288 }
2289
2290 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2291 set_gc_state_mask(UPDATEREFS, in_progress);
2292 }
2293
2294 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2295 ShenandoahCodeRoots::register_nmethod(nm);
2296 }
2297
2298 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2299 ShenandoahCodeRoots::unregister_nmethod(nm);
2300 }
2301
2302 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
2303 ShenandoahCodeRoots::flush_nmethod(nm);
2304 }
2305
2306 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2307 heap_region_containing(o)->record_pin();
2308 return o;
2309 }
2310
2311 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2312 heap_region_containing(o)->record_unpin();
2313 }
2314
2315 void ShenandoahHeap::sync_pinned_region_status() {
2316 ShenandoahHeapLocker locker(lock());
2317
2318 for (size_t i = 0; i < num_regions(); i++) {
2319 ShenandoahHeapRegion *r = get_region(i);
2320 if (r->is_active()) {
2321 if (r->is_pinned()) {
2322 if (r->pin_count() == 0) {
2323 r->make_unpinned();
2324 }
2325 } else {
2326 if (r->pin_count() > 0) {
2327 r->make_pinned();
2328 }
2329 }
2330 }
2331 }
2332
2333 assert_pinned_region_status();
2334 }
2335
2336 #ifdef ASSERT
2337 void ShenandoahHeap::assert_pinned_region_status() {
2338 for (size_t i = 0; i < num_regions(); i++) {
2339 ShenandoahHeapRegion* r = get_region(i);
2340 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2341 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2342 }
2343 }
2344 #endif
2345
2346 GCTimer* ShenandoahHeap::gc_timer() const {
2347 return _gc_timer;
2348 }
2349
2350 void ShenandoahHeap::prepare_concurrent_roots() {
2351 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2352 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
2353 set_concurrent_root_in_progress(true);
2354 }
2355 }
2356
2357 void ShenandoahHeap::prepare_concurrent_unloading() {
2358 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2359 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2360 _unloader.prepare();
2361 }
2362 }
2363
2364 void ShenandoahHeap::finish_concurrent_unloading() {
2365 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2366 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2367 _unloader.finish();
2368 }
2369 }
2370
2371 #ifdef ASSERT
2372 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2373 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2374
2375 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2376 if (UseDynamicNumberOfGCThreads ||
2377 (FLAG_IS_DEFAULT(ParallelGCThreads) && ForceDynamicNumberOfGCThreads)) {
2378 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2379 } else {
2380 // Use ParallelGCThreads inside safepoints
2381 assert(nworkers == ParallelGCThreads, "Use ParalleGCThreads within safepoints");
2382 }
2383 } else {
2384 if (UseDynamicNumberOfGCThreads ||
2385 (FLAG_IS_DEFAULT(ConcGCThreads) && ForceDynamicNumberOfGCThreads)) {
2386 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2387 } else {
2388 // Use ConcGCThreads outside safepoints
2389 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2390 }
2391 }
2392 }
2393 #endif
2394
2395 ShenandoahVerifier* ShenandoahHeap::verifier() {
2396 guarantee(ShenandoahVerify, "Should be enabled");
2397 assert (_verifier != NULL, "sanity");
2398 return _verifier;
2399 }
2400
2401 template<class T>
2402 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2403 private:
2404 T cl;
2405 ShenandoahHeap* _heap;
2406 ShenandoahRegionIterator* _regions;
2407 bool _concurrent;
2408 public:
2409 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2410 AbstractGangTask("Concurrent Update References Task"),
2411 cl(T()),
2412 _heap(ShenandoahHeap::heap()),
2413 _regions(regions),
2414 _concurrent(concurrent) {
2415 }
2416
2417 void work(uint worker_id) {
2418 if (_concurrent) {
2419 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2420 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2421 do_work();
2422 } else {
2423 ShenandoahParallelWorkerSession worker_session(worker_id);
2424 do_work();
2425 }
2426 }
2427
2428 private:
2429 void do_work() {
2430 ShenandoahHeapRegion* r = _regions->next();
2431 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2432 while (r != NULL) {
2433 HeapWord* top_at_start_ur = r->concurrent_iteration_safe_limit();
2434 assert (top_at_start_ur >= r->bottom(), "sanity");
2435 if (r->is_active() && !r->is_cset()) {
2436 _heap->marked_object_oop_iterate(r, &cl, top_at_start_ur);
2437 }
2438 if (ShenandoahPacing) {
2439 _heap->pacer()->report_updaterefs(pointer_delta(top_at_start_ur, r->bottom()));
2440 }
2441 if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
2442 return;
2443 }
2444 r = _regions->next();
2445 }
2446 }
2447 };
2448
2449 void ShenandoahHeap::update_heap_references(bool concurrent) {
2450 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
2451 workers()->run_task(&task);
2452 }
2453
2454 void ShenandoahHeap::op_init_updaterefs() {
2455 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2456
2457 set_evacuation_in_progress(false);
2458
2459 {
2460 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_retire_gclabs);
2461 retire_and_reset_gclabs();
2462 }
2463
2464 if (ShenandoahVerify) {
2465 if (!is_degenerated_gc_in_progress()) {
2466 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2467 }
2468 verifier()->verify_before_updaterefs();
2469 }
2470
2471 set_update_refs_in_progress(true);
2472
2473 {
2474 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_prepare);
2475
2476 make_parsable(true);
2477 for (uint i = 0; i < num_regions(); i++) {
2478 ShenandoahHeapRegion* r = get_region(i);
2479 r->set_concurrent_iteration_safe_limit(r->top());
2480 }
2481
2482 // Reset iterator.
2483 _update_refs_iterator.reset();
2484 }
2485
2486 if (ShenandoahPacing) {
2487 pacer()->setup_for_updaterefs();
2488 }
2489 }
2490
2491 void ShenandoahHeap::op_final_updaterefs() {
2492 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2493
2494 finish_concurrent_unloading();
2495
2496 // Check if there is left-over work, and finish it
2497 if (_update_refs_iterator.has_next()) {
2498 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2499
2500 // Finish updating references where we left off.
2501 clear_cancelled_gc();
2502 update_heap_references(false);
2503 }
2504
2505 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2506 // everything. On degenerated paths, cancelled gc would not be set anyway.
2507 if (cancelled_gc()) {
2508 clear_cancelled_gc();
2509 }
2510 assert(!cancelled_gc(), "Should have been done right before");
2511
2512 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2513 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2514 }
2515
2516 if (is_degenerated_gc_in_progress()) {
2517 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2518 } else {
2519 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2520 }
2521
2522 // Has to be done before cset is clear
2523 if (ShenandoahVerify) {
2524 verifier()->verify_roots_in_to_space();
2525 }
2526
2527 // Drop unnecessary "pinned" state from regions that does not have CP marks
2528 // anymore, as this would allow trashing them below.
2529 {
2530 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_sync_pinned);
2531 sync_pinned_region_status();
2532 }
2533
2534 {
2535 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2536 trash_cset_regions();
2537 }
2538
2539 set_has_forwarded_objects(false);
2540 set_update_refs_in_progress(false);
2541
2542 if (ShenandoahVerify) {
2543 verifier()->verify_after_updaterefs();
2544 }
2545
2546 if (VerifyAfterGC) {
2547 Universe::verify();
2548 }
2549
2550 {
2551 ShenandoahHeapLocker locker(lock());
2552 _free_set->rebuild();
2553 }
2554 }
2555
2556 #ifdef ASSERT
2557 void ShenandoahHeap::assert_heaplock_owned_by_current_thread() {
2558 _lock.assert_owned_by_current_thread();
2559 }
2560
2561 void ShenandoahHeap::assert_heaplock_not_owned_by_current_thread() {
2562 _lock.assert_not_owned_by_current_thread();
2563 }
2564
2565 void ShenandoahHeap::assert_heaplock_or_safepoint() {
2566 _lock.assert_owned_by_current_thread_or_safepoint();
2567 }
2568 #endif
2569
2570 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2571 print_on(st);
2572 print_heap_regions_on(st);
2573 }
2574
2575 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2576 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2577
2578 size_t regions_from = _bitmap_regions_per_slice * slice;
2579 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2580 for (size_t g = regions_from; g < regions_to; g++) {
2581 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2582 if (skip_self && g == r->region_number()) continue;
2583 if (get_region(g)->is_committed()) {
2584 return true;
2585 }
2586 }
2587 return false;
2588 }
2589
2590 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2591 assert_heaplock_owned_by_current_thread();
2592
2593 // Bitmaps in special regions do not need commits
2594 if (_bitmap_region_special) {
2595 return true;
2596 }
2597
2598 if (is_bitmap_slice_committed(r, true)) {
2599 // Some other region from the group is already committed, meaning the bitmap
2600 // slice is already committed, we exit right away.
2601 return true;
2602 }
2603
2604 // Commit the bitmap slice:
2605 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2606 size_t off = _bitmap_bytes_per_slice * slice;
2607 size_t len = _bitmap_bytes_per_slice;
2608 if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) {
2609 return false;
2610 }
2611 return true;
2612 }
2613
2614 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2615 assert_heaplock_owned_by_current_thread();
2616
2617 // Bitmaps in special regions do not need uncommits
2618 if (_bitmap_region_special) {
2619 return true;
2620 }
2621
2622 if (is_bitmap_slice_committed(r, true)) {
2623 // Some other region from the group is still committed, meaning the bitmap
2624 // slice is should stay committed, exit right away.
2625 return true;
2626 }
2627
2628 // Uncommit the bitmap slice:
2629 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2630 size_t off = _bitmap_bytes_per_slice * slice;
2631 size_t len = _bitmap_bytes_per_slice;
2632 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2633 return false;
2634 }
2635 return true;
2636 }
2637
2638 void ShenandoahHeap::safepoint_synchronize_begin() {
2639 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2640 SuspendibleThreadSet::synchronize();
2641 }
2642 }
2643
2644 void ShenandoahHeap::safepoint_synchronize_end() {
2645 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2646 SuspendibleThreadSet::desynchronize();
2647 }
2648 }
2649
2650 void ShenandoahHeap::vmop_entry_init_mark() {
2651 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2652 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2653 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
2654
2655 try_inject_alloc_failure();
2656 VM_ShenandoahInitMark op;
2657 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2658 }
2659
2660 void ShenandoahHeap::vmop_entry_final_mark() {
2661 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2662 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2663 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
2664
2665 try_inject_alloc_failure();
2666 VM_ShenandoahFinalMarkStartEvac op;
2667 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2668 }
2669
2670 void ShenandoahHeap::vmop_entry_final_evac() {
2671 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2672 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2673 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_gross);
2674
2675 VM_ShenandoahFinalEvac op;
2676 VMThread::execute(&op); // jump to entry_final_evac under safepoint
2677 }
2678
2679 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2680 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2681 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2682 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
2683
2684 try_inject_alloc_failure();
2685 VM_ShenandoahInitUpdateRefs op;
2686 VMThread::execute(&op);
2687 }
2688
2689 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2690 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2691 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2692 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
2693
2694 try_inject_alloc_failure();
2695 VM_ShenandoahFinalUpdateRefs op;
2696 VMThread::execute(&op);
2697 }
2698
2699 void ShenandoahHeap::vmop_entry_init_traversal() {
2700 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2701 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2702 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc_gross);
2703
2704 try_inject_alloc_failure();
2705 VM_ShenandoahInitTraversalGC op;
2706 VMThread::execute(&op);
2707 }
2708
2709 void ShenandoahHeap::vmop_entry_final_traversal() {
2710 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2711 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2712 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc_gross);
2713
2714 try_inject_alloc_failure();
2715 VM_ShenandoahFinalTraversalGC op;
2716 VMThread::execute(&op);
2717 }
2718
2719 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2720 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2721 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2722 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
2723
2724 try_inject_alloc_failure();
2725 VM_ShenandoahFullGC op(cause);
2726 VMThread::execute(&op);
2727 }
2728
2729 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2730 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2731 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2732 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
2733
2734 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2735 VMThread::execute(°enerated_gc);
2736 }
2737
2738 void ShenandoahHeap::entry_init_mark() {
2739 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2740 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
2741 const char* msg = init_mark_event_message();
2742 GCTraceTime(Info, gc) time(msg, gc_timer());
2743 EventMark em("%s", msg);
2744
2745 ShenandoahWorkerScope scope(workers(),
2746 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2747 "init marking");
2748
2749 op_init_mark();
2750 }
2751
2752 void ShenandoahHeap::entry_final_mark() {
2753 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2754 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
2755 const char* msg = final_mark_event_message();
2756 GCTraceTime(Info, gc) time(msg, gc_timer());
2757 EventMark em("%s", msg);
2758
2759 ShenandoahWorkerScope scope(workers(),
2760 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2761 "final marking");
2762
2763 op_final_mark();
2764 }
2765
2766 void ShenandoahHeap::entry_final_evac() {
2767 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2768 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac);
2769 static const char* msg = "Pause Final Evac";
2770 GCTraceTime(Info, gc) time(msg, gc_timer());
2771 EventMark em("%s", msg);
2772
2773 op_final_evac();
2774 }
2775
2776 void ShenandoahHeap::entry_init_updaterefs() {
2777 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2778 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
2779
2780 static const char* msg = "Pause Init Update Refs";
2781 GCTraceTime(Info, gc) time(msg, gc_timer());
2782 EventMark em("%s", msg);
2783
2784 // No workers used in this phase, no setup required
2785
2786 op_init_updaterefs();
2787 }
2788
2789 void ShenandoahHeap::entry_final_updaterefs() {
2790 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2791 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
2792
2793 static const char* msg = "Pause Final Update Refs";
2794 GCTraceTime(Info, gc) time(msg, gc_timer());
2795 EventMark em("%s", msg);
2796
2797 ShenandoahWorkerScope scope(workers(),
2798 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2799 "final reference update");
2800
2801 op_final_updaterefs();
2802 }
2803
2804 void ShenandoahHeap::entry_init_traversal() {
2805 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2806 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc);
2807
2808 static const char* msg = init_traversal_event_message();
2809 GCTraceTime(Info, gc) time(msg, gc_timer());
2810 EventMark em("%s", msg);
2811
2812 ShenandoahWorkerScope scope(workers(),
2813 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2814 "init traversal");
2815
2816 op_init_traversal();
2817 }
2818
2819 void ShenandoahHeap::entry_final_traversal() {
2820 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2821 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc);
2822
2823 static const char* msg = final_traversal_event_message();
2824 GCTraceTime(Info, gc) time(msg, gc_timer());
2825 EventMark em("%s", msg);
2826
2827 ShenandoahWorkerScope scope(workers(),
2828 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2829 "final traversal");
2830
2831 op_final_traversal();
2832 }
2833
2834 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2835 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2836 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
2837
2838 static const char* msg = "Pause Full";
2839 GCTraceTime(Info, gc) time(msg, gc_timer(), cause, true);
2840 EventMark em("%s", msg);
2841
2842 ShenandoahWorkerScope scope(workers(),
2843 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2844 "full gc");
2845
2846 op_full(cause);
2847 }
2848
2849 void ShenandoahHeap::entry_degenerated(int point) {
2850 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2851 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
2852
2853 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2854 const char* msg = degen_event_message(dpoint);
2855 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2856 EventMark em("%s", msg);
2857
2858 ShenandoahWorkerScope scope(workers(),
2859 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2860 "stw degenerated gc");
2861
2862 set_degenerated_gc_in_progress(true);
2863 op_degenerated(dpoint);
2864 set_degenerated_gc_in_progress(false);
2865 }
2866
2867 void ShenandoahHeap::entry_mark() {
2868 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2869
2870 const char* msg = conc_mark_event_message();
2871 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2872 EventMark em("%s", msg);
2873
2874 ShenandoahWorkerScope scope(workers(),
2875 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2876 "concurrent marking");
2877
2878 try_inject_alloc_failure();
2879 op_mark();
2880 }
2881
2882 void ShenandoahHeap::entry_evac() {
2883 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
2884 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2885
2886 static const char* msg = "Concurrent evacuation";
2887 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2888 EventMark em("%s", msg);
2889
2890 ShenandoahWorkerScope scope(workers(),
2891 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2892 "concurrent evacuation");
2893
2894 try_inject_alloc_failure();
2895 op_conc_evac();
2896 }
2897
2898 void ShenandoahHeap::entry_updaterefs() {
2899 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
2900
2901 static const char* msg = "Concurrent update references";
2902 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2903 EventMark em("%s", msg);
2904
2905 ShenandoahWorkerScope scope(workers(),
2906 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2907 "concurrent reference update");
2908
2909 try_inject_alloc_failure();
2910 op_updaterefs();
2911 }
2912
2913 void ShenandoahHeap::entry_roots() {
2914 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_roots);
2915
2916 static const char* msg = "Concurrent roots processing";
2917 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2918 EventMark em("%s", msg);
2919
2920 ShenandoahWorkerScope scope(workers(),
2921 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2922 "concurrent root processing");
2923
2924 try_inject_alloc_failure();
2925 op_roots();
2926 }
2927
2928 void ShenandoahHeap::entry_cleanup() {
2929 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup);
2930
2931 static const char* msg = "Concurrent cleanup";
2932 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2933 EventMark em("%s", msg);
2934
2935 // This phase does not use workers, no need for setup
2936
2937 try_inject_alloc_failure();
2938 op_cleanup();
2939 }
2940
2941 void ShenandoahHeap::entry_reset() {
2942 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset);
2943
2944 static const char* msg = "Concurrent reset";
2945 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2946 EventMark em("%s", msg);
2947
2948 ShenandoahWorkerScope scope(workers(),
2949 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2950 "concurrent reset");
2951
2952 try_inject_alloc_failure();
2953 op_reset();
2954 }
2955
2956 void ShenandoahHeap::entry_preclean() {
2957 if (ShenandoahPreclean && process_references()) {
2958 static const char* msg = "Concurrent precleaning";
2959 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2960 EventMark em("%s", msg);
2961
2962 ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
2963
2964 ShenandoahWorkerScope scope(workers(),
2965 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2966 "concurrent preclean",
2967 /* check_workers = */ false);
2968
2969 try_inject_alloc_failure();
2970 op_preclean();
2971 }
2972 }
2973
2974 void ShenandoahHeap::entry_traversal() {
2975 static const char* msg = conc_traversal_event_message();
2976 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2977 EventMark em("%s", msg);
2978
2979 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2980
2981 ShenandoahWorkerScope scope(workers(),
2982 ShenandoahWorkerPolicy::calc_workers_for_conc_traversal(),
2983 "concurrent traversal");
2984
2985 try_inject_alloc_failure();
2986 op_traversal();
2987 }
2988
2989 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2990 static const char *msg = "Concurrent uncommit";
2991 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2992 EventMark em("%s", msg);
2993
2994 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit);
2995
2996 op_uncommit(shrink_before);
2997 }
2998
2999 void ShenandoahHeap::try_inject_alloc_failure() {
3000 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
3001 _inject_alloc_failure.set();
3002 os::naked_short_sleep(1);
3003 if (cancelled_gc()) {
3004 log_info(gc)("Allocation failure was successfully injected");
3005 }
3006 }
3007 }
3008
3009 bool ShenandoahHeap::should_inject_alloc_failure() {
3010 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
3011 }
3012
3013 void ShenandoahHeap::initialize_serviceability() {
3014 _memory_pool = new ShenandoahMemoryPool(this);
3015 _cycle_memory_manager.add_pool(_memory_pool);
3016 _stw_memory_manager.add_pool(_memory_pool);
3017 }
3018
3019 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
3020 GrowableArray<GCMemoryManager*> memory_managers(2);
3021 memory_managers.append(&_cycle_memory_manager);
3022 memory_managers.append(&_stw_memory_manager);
3023 return memory_managers;
3024 }
3025
3026 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
3027 GrowableArray<MemoryPool*> memory_pools(1);
3028 memory_pools.append(_memory_pool);
3029 return memory_pools;
3030 }
3031
3032 MemoryUsage ShenandoahHeap::memory_usage() {
3033 return _memory_pool->get_memory_usage();
3034 }
3035
3036 void ShenandoahHeap::enter_evacuation() {
3037 _oom_evac_handler.enter_evacuation();
3038 }
3039
3040 void ShenandoahHeap::leave_evacuation() {
3041 _oom_evac_handler.leave_evacuation();
3042 }
3043
3044 ShenandoahRegionIterator::ShenandoahRegionIterator() :
3045 _heap(ShenandoahHeap::heap()),
3046 _index(0) {}
3047
3048 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
3049 _heap(heap),
3050 _index(0) {}
3051
3052 void ShenandoahRegionIterator::reset() {
3053 _index = 0;
3054 }
3055
3056 bool ShenandoahRegionIterator::has_next() const {
3057 return _index < _heap->num_regions();
3058 }
3059
3060 char ShenandoahHeap::gc_state() const {
3061 return _gc_state.raw_value();
3062 }
3063
3064 void ShenandoahHeap::deduplicate_string(oop str) {
3065 assert(java_lang_String::is_instance(str), "invariant");
3066
3067 if (ShenandoahStringDedup::is_enabled()) {
3068 ShenandoahStringDedup::deduplicate(str);
3069 }
3070 }
3071
3072 const char* ShenandoahHeap::init_mark_event_message() const {
3073 bool update_refs = has_forwarded_objects();
3074 bool proc_refs = process_references();
3075 bool unload_cls = unload_classes();
3076
3077 if (update_refs && proc_refs && unload_cls) {
3078 return "Pause Init Mark (update refs) (process weakrefs) (unload classes)";
3079 } else if (update_refs && proc_refs) {
3080 return "Pause Init Mark (update refs) (process weakrefs)";
3081 } else if (update_refs && unload_cls) {
3082 return "Pause Init Mark (update refs) (unload classes)";
3083 } else if (proc_refs && unload_cls) {
3084 return "Pause Init Mark (process weakrefs) (unload classes)";
3085 } else if (update_refs) {
3086 return "Pause Init Mark (update refs)";
3087 } else if (proc_refs) {
3088 return "Pause Init Mark (process weakrefs)";
3089 } else if (unload_cls) {
3090 return "Pause Init Mark (unload classes)";
3091 } else {
3092 return "Pause Init Mark";
3093 }
3094 }
3095
3096 const char* ShenandoahHeap::final_mark_event_message() const {
3097 bool update_refs = has_forwarded_objects();
3098 bool proc_refs = process_references();
3099 bool unload_cls = unload_classes();
3100
3101 if (update_refs && proc_refs && unload_cls) {
3102 return "Pause Final Mark (update refs) (process weakrefs) (unload classes)";
3103 } else if (update_refs && proc_refs) {
3104 return "Pause Final Mark (update refs) (process weakrefs)";
3105 } else if (update_refs && unload_cls) {
3106 return "Pause Final Mark (update refs) (unload classes)";
3107 } else if (proc_refs && unload_cls) {
3108 return "Pause Final Mark (process weakrefs) (unload classes)";
3109 } else if (update_refs) {
3110 return "Pause Final Mark (update refs)";
3111 } else if (proc_refs) {
3112 return "Pause Final Mark (process weakrefs)";
3113 } else if (unload_cls) {
3114 return "Pause Final Mark (unload classes)";
3115 } else {
3116 return "Pause Final Mark";
3117 }
3118 }
3119
3120 const char* ShenandoahHeap::conc_mark_event_message() const {
3121 bool update_refs = has_forwarded_objects();
3122 bool proc_refs = process_references();
3123 bool unload_cls = unload_classes();
3124
3125 if (update_refs && proc_refs && unload_cls) {
3126 return "Concurrent marking (update refs) (process weakrefs) (unload classes)";
3127 } else if (update_refs && proc_refs) {
3128 return "Concurrent marking (update refs) (process weakrefs)";
3129 } else if (update_refs && unload_cls) {
3130 return "Concurrent marking (update refs) (unload classes)";
3131 } else if (proc_refs && unload_cls) {
3132 return "Concurrent marking (process weakrefs) (unload classes)";
3133 } else if (update_refs) {
3134 return "Concurrent marking (update refs)";
3135 } else if (proc_refs) {
3136 return "Concurrent marking (process weakrefs)";
3137 } else if (unload_cls) {
3138 return "Concurrent marking (unload classes)";
3139 } else {
3140 return "Concurrent marking";
3141 }
3142 }
3143
3144 const char* ShenandoahHeap::init_traversal_event_message() const {
3145 bool proc_refs = process_references();
3146 bool unload_cls = unload_classes();
3147
3148 if (proc_refs && unload_cls) {
3149 return "Pause Init Traversal (process weakrefs) (unload classes)";
3150 } else if (proc_refs) {
3151 return "Pause Init Traversal (process weakrefs)";
3152 } else if (unload_cls) {
3153 return "Pause Init Traversal (unload classes)";
3154 } else {
3155 return "Pause Init Traversal";
3156 }
3157 }
3158
3159 const char* ShenandoahHeap::final_traversal_event_message() const {
3160 bool proc_refs = process_references();
3161 bool unload_cls = unload_classes();
3162
3163 if (proc_refs && unload_cls) {
3164 return "Pause Final Traversal (process weakrefs) (unload classes)";
3165 } else if (proc_refs) {
3166 return "Pause Final Traversal (process weakrefs)";
3167 } else if (unload_cls) {
3168 return "Pause Final Traversal (unload classes)";
3169 } else {
3170 return "Pause Final Traversal";
3171 }
3172 }
3173
3174 const char* ShenandoahHeap::conc_traversal_event_message() const {
3175 bool proc_refs = process_references();
3176 bool unload_cls = unload_classes();
3177
3178 if (proc_refs && unload_cls) {
3179 return "Concurrent Traversal (process weakrefs) (unload classes)";
3180 } else if (proc_refs) {
3181 return "Concurrent Traversal (process weakrefs)";
3182 } else if (unload_cls) {
3183 return "Concurrent Traversal (unload classes)";
3184 } else {
3185 return "Concurrent Traversal";
3186 }
3187 }
3188
3189 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
3190 switch (point) {
3191 case _degenerated_unset:
3192 return "Pause Degenerated GC (<UNSET>)";
3193 case _degenerated_traversal:
3194 return "Pause Degenerated GC (Traversal)";
3195 case _degenerated_outside_cycle:
3196 return "Pause Degenerated GC (Outside of Cycle)";
3197 case _degenerated_mark:
3198 return "Pause Degenerated GC (Mark)";
3199 case _degenerated_evac:
3200 return "Pause Degenerated GC (Evacuation)";
3201 case _degenerated_updaterefs:
3202 return "Pause Degenerated GC (Update Refs)";
3203 default:
3204 ShouldNotReachHere();
3205 return "ERROR";
3206 }
3207 }
3208
3209 jushort* ShenandoahHeap::get_liveness_cache(uint worker_id) {
3210 #ifdef ASSERT
3211 assert(_liveness_cache != NULL, "sanity");
3212 assert(worker_id < _max_workers, "sanity");
3213 for (uint i = 0; i < num_regions(); i++) {
3214 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
3215 }
3216 #endif
3217 return _liveness_cache[worker_id];
3218 }
3219
3220 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
3221 assert(worker_id < _max_workers, "sanity");
3222 assert(_liveness_cache != NULL, "sanity");
3223 jushort* ld = _liveness_cache[worker_id];
3224 for (uint i = 0; i < num_regions(); i++) {
3225 ShenandoahHeapRegion* r = get_region(i);
3226 jushort live = ld[i];
3227 if (live > 0) {
3228 r->increase_live_data_gc_words(live);
3229 ld[i] = 0;
3230 }
3231 }
3232 }