1 /*
2 * Copyright (c) 2013, 2020, Red Hat, Inc. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.hpp"
27 #include "memory/universe.hpp"
28
29 #include "gc/shared/gcArguments.hpp"
30 #include "gc/shared/gcTimer.hpp"
31 #include "gc/shared/gcTraceTime.inline.hpp"
32 #include "gc/shared/locationPrinter.inline.hpp"
33 #include "gc/shared/memAllocator.hpp"
34 #include "gc/shared/oopStorageSet.hpp"
35 #include "gc/shared/plab.hpp"
36
37 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
38 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
39 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
40 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
41 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
42 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
43 #include "gc/shenandoah/shenandoahControlThread.hpp"
44 #include "gc/shenandoah/shenandoahFreeSet.hpp"
45 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
46 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
47 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
48 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
49 #include "gc/shenandoah/shenandoahMarkCompact.hpp"
50 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
51 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
52 #include "gc/shenandoah/shenandoahMetrics.hpp"
53 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
54 #include "gc/shenandoah/shenandoahNormalMode.hpp"
55 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
56 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
57 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
58 #include "gc/shenandoah/shenandoahPassiveMode.hpp"
59 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
60 #include "gc/shenandoah/shenandoahStringDedup.hpp"
61 #include "gc/shenandoah/shenandoahTaskqueue.hpp"
62 #include "gc/shenandoah/shenandoahTraversalMode.hpp"
63 #include "gc/shenandoah/shenandoahUtils.hpp"
64 #include "gc/shenandoah/shenandoahVerifier.hpp"
65 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
66 #include "gc/shenandoah/shenandoahVMOperations.hpp"
67 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
68 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
69 #if INCLUDE_JFR
70 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
71 #endif
72
73 #include "memory/metaspace.hpp"
74 #include "oops/compressedOops.inline.hpp"
75 #include "runtime/atomic.hpp"
76 #include "runtime/globals.hpp"
77 #include "runtime/interfaceSupport.inline.hpp"
78 #include "runtime/orderAccess.hpp"
79 #include "runtime/safepointMechanism.hpp"
80 #include "runtime/vmThread.hpp"
81 #include "services/mallocTracker.hpp"
82 #include "utilities/powerOfTwo.hpp"
83
84 #ifdef ASSERT
85 template <class T>
86 void ShenandoahAssertToSpaceClosure::do_oop_work(T* p) {
87 T o = RawAccess<>::oop_load(p);
88 if (! CompressedOops::is_null(o)) {
89 oop obj = CompressedOops::decode_not_null(o);
90 shenandoah_assert_not_forwarded(p, obj);
91 }
92 }
93
94 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_work(p); }
95 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_work(p); }
96 #endif
97
98 class ShenandoahPretouchHeapTask : public AbstractGangTask {
99 private:
100 ShenandoahRegionIterator _regions;
101 const size_t _page_size;
102 public:
103 ShenandoahPretouchHeapTask(size_t page_size) :
104 AbstractGangTask("Shenandoah Pretouch Heap"),
105 _page_size(page_size) {}
106
107 virtual void work(uint worker_id) {
108 ShenandoahHeapRegion* r = _regions.next();
109 while (r != NULL) {
110 os::pretouch_memory(r->bottom(), r->end(), _page_size);
111 r = _regions.next();
112 }
113 }
114 };
115
116 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
117 private:
118 ShenandoahRegionIterator _regions;
119 char* _bitmap_base;
120 const size_t _bitmap_size;
121 const size_t _page_size;
122 public:
123 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
124 AbstractGangTask("Shenandoah Pretouch Bitmap"),
125 _bitmap_base(bitmap_base),
126 _bitmap_size(bitmap_size),
127 _page_size(page_size) {}
128
129 virtual void work(uint worker_id) {
130 ShenandoahHeapRegion* r = _regions.next();
131 while (r != NULL) {
132 size_t start = r->region_number() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
133 size_t end = (r->region_number() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
134 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
135
136 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
137
138 r = _regions.next();
139 }
140 }
141 };
142
143 jint ShenandoahHeap::initialize() {
144 initialize_heuristics();
145
146 //
147 // Figure out heap sizing
148 //
149
150 size_t init_byte_size = InitialHeapSize;
151 size_t min_byte_size = MinHeapSize;
152 size_t max_byte_size = MaxHeapSize;
153 size_t heap_alignment = HeapAlignment;
154
155 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
156
157 if (ShenandoahAlwaysPreTouch) {
158 // Enabled pre-touch means the entire heap is committed right away.
159 init_byte_size = max_byte_size;
160 }
161
162 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
163 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
164
165 _num_regions = ShenandoahHeapRegion::region_count();
166
167 size_t num_committed_regions = init_byte_size / reg_size_bytes;
168 num_committed_regions = MIN2(num_committed_regions, _num_regions);
169 assert(num_committed_regions <= _num_regions, "sanity");
170 _initial_size = num_committed_regions * reg_size_bytes;
171
172 size_t num_min_regions = min_byte_size / reg_size_bytes;
173 num_min_regions = MIN2(num_min_regions, _num_regions);
174 assert(num_min_regions <= _num_regions, "sanity");
175 _minimum_size = num_min_regions * reg_size_bytes;
176
177 _committed = _initial_size;
178
179 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
180 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
181
182 //
183 // Reserve and commit memory for heap
184 //
185
186 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
187 initialize_reserved_region(heap_rs);
188 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
189 _heap_region_special = heap_rs.special();
190
191 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
192 "Misaligned heap: " PTR_FORMAT, p2i(base()));
193
194 #if SHENANDOAH_OPTIMIZED_OBJTASK
195 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
196 // Fail if we ever attempt to address more than we can.
197 if ((uintptr_t)heap_rs.end() >= ObjArrayChunkedTask::max_addressable()) {
198 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
199 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
200 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
201 p2i(heap_rs.base()), p2i(heap_rs.end()), ObjArrayChunkedTask::max_addressable());
202 vm_exit_during_initialization("Fatal Error", buf);
203 }
204 #endif
205
206 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
207 if (!_heap_region_special) {
208 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
209 "Cannot commit heap memory");
210 }
211
212 //
213 // Reserve and commit memory for bitmap(s)
214 //
215
216 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
217 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
218
219 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
220
221 guarantee(bitmap_bytes_per_region != 0,
222 "Bitmap bytes per region should not be zero");
223 guarantee(is_power_of_2(bitmap_bytes_per_region),
224 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
225
226 if (bitmap_page_size > bitmap_bytes_per_region) {
227 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
228 _bitmap_bytes_per_slice = bitmap_page_size;
229 } else {
230 _bitmap_regions_per_slice = 1;
231 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
232 }
233
234 guarantee(_bitmap_regions_per_slice >= 1,
235 "Should have at least one region per slice: " SIZE_FORMAT,
236 _bitmap_regions_per_slice);
237
238 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
239 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
240 _bitmap_bytes_per_slice, bitmap_page_size);
241
242 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
243 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
244 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
245 _bitmap_region_special = bitmap.special();
246
247 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
248 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
249 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
250 if (!_bitmap_region_special) {
251 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
252 "Cannot commit bitmap memory");
253 }
254
255 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
256
257 if (ShenandoahVerify) {
258 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
259 if (!verify_bitmap.special()) {
260 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
261 "Cannot commit verification bitmap memory");
262 }
263 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
264 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
265 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
266 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
267 }
268
269 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
270 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
271 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
272 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
273 _aux_bitmap_region_special = aux_bitmap.special();
274 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
275
276 //
277 // Create regions and region sets
278 //
279
280 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
281 _free_set = new ShenandoahFreeSet(this, _num_regions);
282 _collection_set = new ShenandoahCollectionSet(this, sh_rs.base(), sh_rs.size());
283
284 {
285 ShenandoahHeapLocker locker(lock());
286
287 size_t size_words = ShenandoahHeapRegion::region_size_words();
288
289 for (size_t i = 0; i < _num_regions; i++) {
290 HeapWord* start = (HeapWord*)sh_rs.base() + size_words * i;
291 bool is_committed = i < num_committed_regions;
292 ShenandoahHeapRegion* r = new ShenandoahHeapRegion(this, start, size_words, i, is_committed);
293
294 _marking_context->initialize_top_at_mark_start(r);
295 _regions[i] = r;
296 assert(!collection_set()->is_in(i), "New region should not be in collection set");
297 }
298
299 // Initialize to complete
300 _marking_context->mark_complete();
301
302 _free_set->rebuild();
303 }
304
305 if (ShenandoahAlwaysPreTouch) {
306 assert(!AlwaysPreTouch, "Should have been overridden");
307
308 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
309 // before initialize() below zeroes it with initializing thread. For any given region,
310 // we touch the region and the corresponding bitmaps from the same thread.
311 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
312
313 size_t pretouch_heap_page_size = heap_page_size;
314 size_t pretouch_bitmap_page_size = bitmap_page_size;
315
316 #ifdef LINUX
317 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
318 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
319 // them into huge one. Therefore, we need to pretouch with smaller pages.
320 if (UseTransparentHugePages) {
321 pretouch_heap_page_size = (size_t)os::vm_page_size();
322 pretouch_bitmap_page_size = (size_t)os::vm_page_size();
323 }
324 #endif
325
326 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
327 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
328
329 log_info(gc, init)("Pretouch bitmap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
330 _num_regions, pretouch_bitmap_page_size);
331 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, pretouch_bitmap_page_size);
332 _workers->run_task(&bcl);
333
334 log_info(gc, init)("Pretouch heap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
335 _num_regions, pretouch_heap_page_size);
336 ShenandoahPretouchHeapTask hcl(pretouch_heap_page_size);
337 _workers->run_task(&hcl);
338 }
339
340 //
341 // Initialize the rest of GC subsystems
342 //
343
344 _liveness_cache = NEW_C_HEAP_ARRAY(jushort*, _max_workers, mtGC);
345 for (uint worker = 0; worker < _max_workers; worker++) {
346 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(jushort, _num_regions, mtGC);
347 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(jushort));
348 }
349
350 // There should probably be Shenandoah-specific options for these,
351 // just as there are G1-specific options.
352 {
353 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
354 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
355 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
356 }
357
358 _monitoring_support = new ShenandoahMonitoringSupport(this);
359 _phase_timings = new ShenandoahPhaseTimings();
360 ShenandoahStringDedup::initialize();
361 ShenandoahCodeRoots::initialize();
362
363 if (ShenandoahPacing) {
364 _pacer = new ShenandoahPacer(this);
365 _pacer->setup_for_idle();
366 } else {
367 _pacer = NULL;
368 }
369
370 _traversal_gc = strcmp(ShenandoahGCMode, "traversal") == 0 ?
371 new ShenandoahTraversalGC(this, _num_regions) :
372 NULL;
373
374 _control_thread = new ShenandoahControlThread();
375
376 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max",
377 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size),
378 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size),
379 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity())
380 );
381
382 log_info(gc, init)("Safepointing mechanism: %s",
383 SafepointMechanism::uses_thread_local_poll() ? "thread-local poll" :
384 (SafepointMechanism::uses_global_page_poll() ? "global-page poll" : "unknown"));
385
386 return JNI_OK;
387 }
388
389 void ShenandoahHeap::initialize_heuristics() {
390 if (ShenandoahGCMode != NULL) {
391 if (strcmp(ShenandoahGCMode, "traversal") == 0) {
392 _gc_mode = new ShenandoahTraversalMode();
393 } else if (strcmp(ShenandoahGCMode, "normal") == 0) {
394 _gc_mode = new ShenandoahNormalMode();
395 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
396 _gc_mode = new ShenandoahPassiveMode();
397 } else {
398 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
399 }
400 } else {
401 ShouldNotReachHere();
402 }
403 _gc_mode->initialize_flags();
404 _heuristics = _gc_mode->initialize_heuristics();
405
406 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
407 vm_exit_during_initialization(
408 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
409 _heuristics->name()));
410 }
411 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
412 vm_exit_during_initialization(
413 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
414 _heuristics->name()));
415 }
416 log_info(gc, init)("Shenandoah heuristics: %s",
417 _heuristics->name());
418 }
419
420 #ifdef _MSC_VER
421 #pragma warning( push )
422 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
423 #endif
424
425 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
426 CollectedHeap(),
427 _initial_size(0),
428 _used(0),
429 _committed(0),
430 _bytes_allocated_since_gc_start(0),
431 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
432 _workers(NULL),
433 _safepoint_workers(NULL),
434 _heap_region_special(false),
435 _num_regions(0),
436 _regions(NULL),
437 _update_refs_iterator(this),
438 _control_thread(NULL),
439 _shenandoah_policy(policy),
440 _heuristics(NULL),
441 _free_set(NULL),
442 _scm(new ShenandoahConcurrentMark()),
443 _traversal_gc(NULL),
444 _full_gc(new ShenandoahMarkCompact()),
445 _pacer(NULL),
446 _verifier(NULL),
447 _phase_timings(NULL),
448 _monitoring_support(NULL),
449 _memory_pool(NULL),
450 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
451 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
452 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
453 _soft_ref_policy(),
454 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
455 _ref_processor(NULL),
456 _marking_context(NULL),
457 _bitmap_size(0),
458 _bitmap_regions_per_slice(0),
459 _bitmap_bytes_per_slice(0),
460 _bitmap_region_special(false),
461 _aux_bitmap_region_special(false),
462 _liveness_cache(NULL),
463 _collection_set(NULL)
464 {
465 log_info(gc, init)("GC threads: " UINT32_FORMAT " parallel, " UINT32_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
466 log_info(gc, init)("Reference processing: %s", ParallelRefProcEnabled ? "parallel" : "serial");
467
468 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
469
470 _max_workers = MAX2(_max_workers, 1U);
471 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
472 /* are_GC_task_threads */ true,
473 /* are_ConcurrentGC_threads */ true);
474 if (_workers == NULL) {
475 vm_exit_during_initialization("Failed necessary allocation.");
476 } else {
477 _workers->initialize_workers();
478 }
479
480 if (ParallelGCThreads > 1) {
481 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
482 ParallelGCThreads,
483 /* are_GC_task_threads */ false,
484 /* are_ConcurrentGC_threads */ false);
485 _safepoint_workers->initialize_workers();
486 }
487 }
488
489 #ifdef _MSC_VER
490 #pragma warning( pop )
491 #endif
492
493 class ShenandoahResetBitmapTask : public AbstractGangTask {
494 private:
495 ShenandoahRegionIterator _regions;
496
497 public:
498 ShenandoahResetBitmapTask() :
499 AbstractGangTask("Parallel Reset Bitmap Task") {}
500
501 void work(uint worker_id) {
502 ShenandoahHeapRegion* region = _regions.next();
503 ShenandoahHeap* heap = ShenandoahHeap::heap();
504 ShenandoahMarkingContext* const ctx = heap->marking_context();
505 while (region != NULL) {
506 if (heap->is_bitmap_slice_committed(region)) {
507 ctx->clear_bitmap(region);
508 }
509 region = _regions.next();
510 }
511 }
512 };
513
514 void ShenandoahHeap::reset_mark_bitmap() {
515 assert_gc_workers(_workers->active_workers());
516 mark_incomplete_marking_context();
517
518 ShenandoahResetBitmapTask task;
519 _workers->run_task(&task);
520 }
521
522 void ShenandoahHeap::print_on(outputStream* st) const {
523 st->print_cr("Shenandoah Heap");
524 st->print_cr(" " SIZE_FORMAT "%s total, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
525 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
526 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
527 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
528 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
529 num_regions(),
530 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
531 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
532
533 st->print("Status: ");
534 if (has_forwarded_objects()) st->print("has forwarded objects, ");
535 if (is_concurrent_mark_in_progress()) st->print("marking, ");
536 if (is_evacuation_in_progress()) st->print("evacuating, ");
537 if (is_update_refs_in_progress()) st->print("updating refs, ");
538 if (is_concurrent_traversal_in_progress()) st->print("traversal, ");
539 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
540 if (is_full_gc_in_progress()) st->print("full gc, ");
541 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
542 if (is_concurrent_root_in_progress()) st->print("concurrent roots, ");
543
544 if (cancelled_gc()) {
545 st->print("cancelled");
546 } else {
547 st->print("not cancelled");
548 }
549 st->cr();
550
551 st->print_cr("Reserved region:");
552 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
553 p2i(reserved_region().start()),
554 p2i(reserved_region().end()));
555
556 ShenandoahCollectionSet* cset = collection_set();
557 st->print_cr("Collection set:");
558 if (cset != NULL) {
559 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
560 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
561 } else {
562 st->print_cr(" (NULL)");
563 }
564
565 st->cr();
566 MetaspaceUtils::print_on(st);
567
568 if (Verbose) {
569 print_heap_regions_on(st);
570 }
571 }
572
573 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
574 public:
575 void do_thread(Thread* thread) {
576 assert(thread != NULL, "Sanity");
577 assert(thread->is_Worker_thread(), "Only worker thread expected");
578 ShenandoahThreadLocalData::initialize_gclab(thread);
579 }
580 };
581
582 void ShenandoahHeap::post_initialize() {
583 CollectedHeap::post_initialize();
584 MutexLocker ml(Threads_lock);
585
586 ShenandoahInitWorkerGCLABClosure init_gclabs;
587 _workers->threads_do(&init_gclabs);
588
589 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
590 // Now, we will let WorkGang to initialize gclab when new worker is created.
591 _workers->set_initialize_gclab();
592
593 _scm->initialize(_max_workers);
594 _full_gc->initialize(_gc_timer);
595
596 ref_processing_init();
597
598 _heuristics->initialize();
599
600 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
601 }
602
603 size_t ShenandoahHeap::used() const {
604 return Atomic::load_acquire(&_used);
605 }
606
607 size_t ShenandoahHeap::committed() const {
608 OrderAccess::acquire();
609 return _committed;
610 }
611
612 void ShenandoahHeap::increase_committed(size_t bytes) {
613 assert_heaplock_or_safepoint();
614 _committed += bytes;
615 }
616
617 void ShenandoahHeap::decrease_committed(size_t bytes) {
618 assert_heaplock_or_safepoint();
619 _committed -= bytes;
620 }
621
622 void ShenandoahHeap::increase_used(size_t bytes) {
623 Atomic::add(&_used, bytes);
624 }
625
626 void ShenandoahHeap::set_used(size_t bytes) {
627 Atomic::release_store_fence(&_used, bytes);
628 }
629
630 void ShenandoahHeap::decrease_used(size_t bytes) {
631 assert(used() >= bytes, "never decrease heap size by more than we've left");
632 Atomic::sub(&_used, bytes);
633 }
634
635 void ShenandoahHeap::increase_allocated(size_t bytes) {
636 Atomic::add(&_bytes_allocated_since_gc_start, bytes);
637 }
638
639 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
640 size_t bytes = words * HeapWordSize;
641 if (!waste) {
642 increase_used(bytes);
643 }
644 increase_allocated(bytes);
645 if (ShenandoahPacing) {
646 control_thread()->pacing_notify_alloc(words);
647 if (waste) {
648 pacer()->claim_for_alloc(words, true);
649 }
650 }
651 }
652
653 size_t ShenandoahHeap::capacity() const {
654 return committed();
655 }
656
657 size_t ShenandoahHeap::max_capacity() const {
658 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
659 }
660
661 size_t ShenandoahHeap::min_capacity() const {
662 return _minimum_size;
663 }
664
665 size_t ShenandoahHeap::initial_capacity() const {
666 return _initial_size;
667 }
668
669 bool ShenandoahHeap::is_in(const void* p) const {
670 HeapWord* heap_base = (HeapWord*) base();
671 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
672 return p >= heap_base && p < last_region_end;
673 }
674
675 void ShenandoahHeap::op_uncommit(double shrink_before) {
676 assert (ShenandoahUncommit, "should be enabled");
677
678 // Application allocates from the beginning of the heap, and GC allocates at
679 // the end of it. It is more efficient to uncommit from the end, so that applications
680 // could enjoy the near committed regions. GC allocations are much less frequent,
681 // and therefore can accept the committing costs.
682
683 size_t count = 0;
684 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
685 ShenandoahHeapRegion* r = get_region(i - 1);
686 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
687 ShenandoahHeapLocker locker(lock());
688 if (r->is_empty_committed()) {
689 // Do not uncommit below minimal capacity
690 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
691 break;
692 }
693
694 r->make_uncommitted();
695 count++;
696 }
697 }
698 SpinPause(); // allow allocators to take the lock
699 }
700
701 if (count > 0) {
702 control_thread()->notify_heap_changed();
703 }
704 }
705
706 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
707 // New object should fit the GCLAB size
708 size_t min_size = MAX2(size, PLAB::min_size());
709
710 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
711 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
712 new_size = MIN2(new_size, PLAB::max_size());
713 new_size = MAX2(new_size, PLAB::min_size());
714
715 // Record new heuristic value even if we take any shortcut. This captures
716 // the case when moderately-sized objects always take a shortcut. At some point,
717 // heuristics should catch up with them.
718 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
719
720 if (new_size < size) {
721 // New size still does not fit the object. Fall back to shared allocation.
722 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
723 return NULL;
724 }
725
726 // Retire current GCLAB, and allocate a new one.
727 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
728 gclab->retire();
729
730 size_t actual_size = 0;
731 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
732 if (gclab_buf == NULL) {
733 return NULL;
734 }
735
736 assert (size <= actual_size, "allocation should fit");
737
738 if (ZeroTLAB) {
739 // ..and clear it.
740 Copy::zero_to_words(gclab_buf, actual_size);
741 } else {
742 // ...and zap just allocated object.
743 #ifdef ASSERT
744 // Skip mangling the space corresponding to the object header to
745 // ensure that the returned space is not considered parsable by
746 // any concurrent GC thread.
747 size_t hdr_size = oopDesc::header_size();
748 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
749 #endif // ASSERT
750 }
751 gclab->set_buf(gclab_buf, actual_size);
752 return gclab->allocate(size);
753 }
754
755 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
756 size_t requested_size,
757 size_t* actual_size) {
758 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
759 HeapWord* res = allocate_memory(req);
760 if (res != NULL) {
761 *actual_size = req.actual_size();
762 } else {
763 *actual_size = 0;
764 }
765 return res;
766 }
767
768 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
769 size_t word_size,
770 size_t* actual_size) {
771 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
772 HeapWord* res = allocate_memory(req);
773 if (res != NULL) {
774 *actual_size = req.actual_size();
775 } else {
776 *actual_size = 0;
777 }
778 return res;
779 }
780
781 ShenandoahHeap* ShenandoahHeap::heap() {
782 CollectedHeap* heap = Universe::heap();
783 assert(heap != NULL, "Unitialized access to ShenandoahHeap::heap()");
784 assert(heap->kind() == CollectedHeap::Shenandoah, "not a shenandoah heap");
785 return (ShenandoahHeap*) heap;
786 }
787
788 ShenandoahHeap* ShenandoahHeap::heap_no_check() {
789 CollectedHeap* heap = Universe::heap();
790 return (ShenandoahHeap*) heap;
791 }
792
793 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
794 intptr_t pacer_epoch = 0;
795 bool in_new_region = false;
796 HeapWord* result = NULL;
797
798 if (req.is_mutator_alloc()) {
799 if (ShenandoahPacing) {
800 pacer()->pace_for_alloc(req.size());
801 pacer_epoch = pacer()->epoch();
802 }
803
804 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
805 result = allocate_memory_under_lock(req, in_new_region);
806 }
807
808 // Allocation failed, block until control thread reacted, then retry allocation.
809 //
810 // It might happen that one of the threads requesting allocation would unblock
811 // way later after GC happened, only to fail the second allocation, because
812 // other threads have already depleted the free storage. In this case, a better
813 // strategy is to try again, as long as GC makes progress.
814 //
815 // Then, we need to make sure the allocation was retried after at least one
816 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
817
818 size_t tries = 0;
819
820 while (result == NULL && _progress_last_gc.is_set()) {
821 tries++;
822 control_thread()->handle_alloc_failure(req.size());
823 result = allocate_memory_under_lock(req, in_new_region);
824 }
825
826 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
827 tries++;
828 control_thread()->handle_alloc_failure(req.size());
829 result = allocate_memory_under_lock(req, in_new_region);
830 }
831
832 } else {
833 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
834 result = allocate_memory_under_lock(req, in_new_region);
835 // Do not call handle_alloc_failure() here, because we cannot block.
836 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
837 }
838
839 if (in_new_region) {
840 control_thread()->notify_heap_changed();
841 }
842
843 if (result != NULL) {
844 size_t requested = req.size();
845 size_t actual = req.actual_size();
846
847 assert (req.is_lab_alloc() || (requested == actual),
848 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
849 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
850
851 if (req.is_mutator_alloc()) {
852 notify_mutator_alloc_words(actual, false);
853
854 // If we requested more than we were granted, give the rest back to pacer.
855 // This only matters if we are in the same pacing epoch: do not try to unpace
856 // over the budget for the other phase.
857 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
858 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
859 }
860 } else {
861 increase_used(actual*HeapWordSize);
862 }
863 }
864
865 return result;
866 }
867
868 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
869 ShenandoahHeapLocker locker(lock());
870 return _free_set->allocate(req, in_new_region);
871 }
872
873 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
874 bool* gc_overhead_limit_was_exceeded) {
875 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
876 return allocate_memory(req);
877 }
878
879 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
880 size_t size,
881 Metaspace::MetadataType mdtype) {
882 MetaWord* result;
883
884 // Inform metaspace OOM to GC heuristics if class unloading is possible.
885 if (heuristics()->can_unload_classes()) {
886 ShenandoahHeuristics* h = heuristics();
887 h->record_metaspace_oom();
888 }
889
890 // Expand and retry allocation
891 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
892 if (result != NULL) {
893 return result;
894 }
895
896 // Start full GC
897 collect(GCCause::_metadata_GC_clear_soft_refs);
898
899 // Retry allocation
900 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
901 if (result != NULL) {
902 return result;
903 }
904
905 // Expand and retry allocation
906 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
907 if (result != NULL) {
908 return result;
909 }
910
911 // Out of memory
912 return NULL;
913 }
914
915 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
916 private:
917 ShenandoahHeap* const _heap;
918 Thread* const _thread;
919 public:
920 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
921 _heap(heap), _thread(Thread::current()) {}
922
923 void do_object(oop p) {
924 shenandoah_assert_marked(NULL, p);
925 if (!p->is_forwarded()) {
926 _heap->evacuate_object(p, _thread);
927 }
928 }
929 };
930
931 class ShenandoahEvacuationTask : public AbstractGangTask {
932 private:
933 ShenandoahHeap* const _sh;
934 ShenandoahCollectionSet* const _cs;
935 bool _concurrent;
936 public:
937 ShenandoahEvacuationTask(ShenandoahHeap* sh,
938 ShenandoahCollectionSet* cs,
939 bool concurrent) :
940 AbstractGangTask("Parallel Evacuation Task"),
941 _sh(sh),
942 _cs(cs),
943 _concurrent(concurrent)
944 {}
945
946 void work(uint worker_id) {
947 if (_concurrent) {
948 ShenandoahConcurrentWorkerSession worker_session(worker_id);
949 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
950 ShenandoahEvacOOMScope oom_evac_scope;
951 do_work();
952 } else {
953 ShenandoahParallelWorkerSession worker_session(worker_id);
954 ShenandoahEvacOOMScope oom_evac_scope;
955 do_work();
956 }
957 }
958
959 private:
960 void do_work() {
961 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
962 ShenandoahHeapRegion* r;
963 while ((r =_cs->claim_next()) != NULL) {
964 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->region_number());
965 _sh->marked_object_iterate(r, &cl);
966
967 if (ShenandoahPacing) {
968 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
969 }
970
971 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
972 break;
973 }
974 }
975 }
976 };
977
978 void ShenandoahHeap::trash_cset_regions() {
979 ShenandoahHeapLocker locker(lock());
980
981 ShenandoahCollectionSet* set = collection_set();
982 ShenandoahHeapRegion* r;
983 set->clear_current_index();
984 while ((r = set->next()) != NULL) {
985 r->make_trash();
986 }
987 collection_set()->clear();
988 }
989
990 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
991 st->print_cr("Heap Regions:");
992 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
993 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
994 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start (previous, next)");
995 st->print_cr("SN=alloc sequence numbers (first mutator, last mutator, first gc, last gc)");
996
997 for (size_t i = 0; i < num_regions(); i++) {
998 get_region(i)->print_on(st);
999 }
1000 }
1001
1002 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1003 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1004
1005 oop humongous_obj = oop(start->bottom());
1006 size_t size = humongous_obj->size();
1007 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1008 size_t index = start->region_number() + required_regions - 1;
1009
1010 assert(!start->has_live(), "liveness must be zero");
1011
1012 for(size_t i = 0; i < required_regions; i++) {
1013 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1014 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1015 ShenandoahHeapRegion* region = get_region(index --);
1016
1017 assert(region->is_humongous(), "expect correct humongous start or continuation");
1018 assert(!region->is_cset(), "Humongous region should not be in collection set");
1019
1020 region->make_trash_immediate();
1021 }
1022 }
1023
1024 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1025 public:
1026 void do_thread(Thread* thread) {
1027 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1028 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1029 gclab->retire();
1030 }
1031 };
1032
1033 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
1034 if (UseTLAB) {
1035 CollectedHeap::ensure_parsability(retire_tlabs);
1036 }
1037 ShenandoahRetireGCLABClosure cl;
1038 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1039 cl.do_thread(t);
1040 }
1041 workers()->threads_do(&cl);
1042 }
1043
1044 void ShenandoahHeap::resize_tlabs() {
1045 CollectedHeap::resize_all_tlabs();
1046 }
1047
1048 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1049 private:
1050 ShenandoahRootEvacuator* _rp;
1051
1052 public:
1053 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1054 AbstractGangTask("Shenandoah evacuate and update roots"),
1055 _rp(rp) {}
1056
1057 void work(uint worker_id) {
1058 ShenandoahParallelWorkerSession worker_session(worker_id);
1059 ShenandoahEvacOOMScope oom_evac_scope;
1060 ShenandoahEvacuateUpdateRootsClosure<> cl;
1061 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1062 _rp->roots_do(worker_id, &cl);
1063 }
1064 };
1065
1066 void ShenandoahHeap::evacuate_and_update_roots() {
1067 #if COMPILER2_OR_JVMCI
1068 DerivedPointerTable::clear();
1069 #endif
1070 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1071 {
1072 // Include concurrent roots if current cycle can not process those roots concurrently
1073 ShenandoahRootEvacuator rp(workers()->active_workers(),
1074 ShenandoahPhaseTimings::init_evac,
1075 !ShenandoahConcurrentRoots::should_do_concurrent_roots(),
1076 !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
1077 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1078 workers()->run_task(&roots_task);
1079 }
1080
1081 #if COMPILER2_OR_JVMCI
1082 DerivedPointerTable::update_pointers();
1083 #endif
1084 }
1085
1086 // Returns size in bytes
1087 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1088 if (ShenandoahElasticTLAB) {
1089 // With Elastic TLABs, return the max allowed size, and let the allocation path
1090 // figure out the safe size for current allocation.
1091 return ShenandoahHeapRegion::max_tlab_size_bytes();
1092 } else {
1093 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1094 }
1095 }
1096
1097 size_t ShenandoahHeap::max_tlab_size() const {
1098 // Returns size in words
1099 return ShenandoahHeapRegion::max_tlab_size_words();
1100 }
1101
1102 class ShenandoahRetireAndResetGCLABClosure : public ThreadClosure {
1103 public:
1104 void do_thread(Thread* thread) {
1105 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1106 gclab->retire();
1107 if (ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1108 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1109 }
1110 }
1111 };
1112
1113 void ShenandoahHeap::retire_and_reset_gclabs() {
1114 ShenandoahRetireAndResetGCLABClosure cl;
1115 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1116 cl.do_thread(t);
1117 }
1118 workers()->threads_do(&cl);
1119 }
1120
1121 void ShenandoahHeap::collect(GCCause::Cause cause) {
1122 control_thread()->request_gc(cause);
1123 }
1124
1125 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1126 //assert(false, "Shouldn't need to do full collections");
1127 }
1128
1129 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1130 Space* sp = heap_region_containing(addr);
1131 if (sp != NULL) {
1132 return sp->block_start(addr);
1133 }
1134 return NULL;
1135 }
1136
1137 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1138 Space* sp = heap_region_containing(addr);
1139 return sp->block_is_obj(addr);
1140 }
1141
1142 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1143 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1144 }
1145
1146 jlong ShenandoahHeap::millis_since_last_gc() {
1147 double v = heuristics()->time_since_last_gc() * 1000;
1148 assert(0 <= v && v <= max_jlong, "value should fit: %f", v);
1149 return (jlong)v;
1150 }
1151
1152 void ShenandoahHeap::prepare_for_verify() {
1153 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1154 make_parsable(false);
1155 }
1156 }
1157
1158 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1159 workers()->print_worker_threads_on(st);
1160 if (ShenandoahStringDedup::is_enabled()) {
1161 ShenandoahStringDedup::print_worker_threads_on(st);
1162 }
1163 }
1164
1165 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1166 workers()->threads_do(tcl);
1167 if (_safepoint_workers != NULL) {
1168 _safepoint_workers->threads_do(tcl);
1169 }
1170 if (ShenandoahStringDedup::is_enabled()) {
1171 ShenandoahStringDedup::threads_do(tcl);
1172 }
1173 }
1174
1175 void ShenandoahHeap::print_tracing_info() const {
1176 LogTarget(Info, gc, stats) lt;
1177 if (lt.is_enabled()) {
1178 ResourceMark rm;
1179 LogStream ls(lt);
1180
1181 phase_timings()->print_on(&ls);
1182
1183 ls.cr();
1184 ls.cr();
1185
1186 shenandoah_policy()->print_gc_stats(&ls);
1187
1188 ls.cr();
1189 ls.cr();
1190
1191 if (ShenandoahPacing) {
1192 pacer()->print_on(&ls);
1193 }
1194
1195 ls.cr();
1196 ls.cr();
1197 }
1198 }
1199
1200 void ShenandoahHeap::verify(VerifyOption vo) {
1201 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1202 if (ShenandoahVerify) {
1203 verifier()->verify_generic(vo);
1204 } else {
1205 // TODO: Consider allocating verification bitmaps on demand,
1206 // and turn this on unconditionally.
1207 }
1208 }
1209 }
1210 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1211 return _free_set->capacity();
1212 }
1213
1214 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1215 private:
1216 MarkBitMap* _bitmap;
1217 Stack<oop,mtGC>* _oop_stack;
1218 ShenandoahHeap* const _heap;
1219 ShenandoahMarkingContext* const _marking_context;
1220
1221 template <class T>
1222 void do_oop_work(T* p) {
1223 T o = RawAccess<>::oop_load(p);
1224 if (!CompressedOops::is_null(o)) {
1225 oop obj = CompressedOops::decode_not_null(o);
1226 if (_heap->is_concurrent_root_in_progress() && !_marking_context->is_marked(obj)) {
1227 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1228 return;
1229 }
1230 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1231
1232 assert(oopDesc::is_oop(obj), "must be a valid oop");
1233 if (!_bitmap->is_marked(obj)) {
1234 _bitmap->mark(obj);
1235 _oop_stack->push(obj);
1236 }
1237 }
1238 }
1239 public:
1240 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1241 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1242 _marking_context(_heap->marking_context()) {}
1243 void do_oop(oop* p) { do_oop_work(p); }
1244 void do_oop(narrowOop* p) { do_oop_work(p); }
1245 };
1246
1247 /*
1248 * This is public API, used in preparation of object_iterate().
1249 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1250 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1251 * control, we call SH::make_tlabs_parsable().
1252 */
1253 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1254 // No-op.
1255 }
1256
1257 /*
1258 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1259 *
1260 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1261 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1262 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1263 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1264 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1265 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1266 * wiped the bitmap in preparation for next marking).
1267 *
1268 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1269 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1270 * is allowed to report dead objects, but is not required to do so.
1271 */
1272 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1273 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1274 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1275 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1276 return;
1277 }
1278
1279 // Reset bitmap
1280 _aux_bit_map.clear();
1281
1282 Stack<oop,mtGC> oop_stack;
1283
1284 // First, we process GC roots according to current GC cycle. This populates the work stack with initial objects.
1285 ShenandoahHeapIterationRootScanner rp;
1286 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1287
1288 rp.roots_do(&oops);
1289
1290 // Work through the oop stack to traverse heap.
1291 while (! oop_stack.is_empty()) {
1292 oop obj = oop_stack.pop();
1293 assert(oopDesc::is_oop(obj), "must be a valid oop");
1294 cl->do_object(obj);
1295 obj->oop_iterate(&oops);
1296 }
1297
1298 assert(oop_stack.is_empty(), "should be empty");
1299
1300 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1301 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1302 }
1303 }
1304
1305 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1306 void ShenandoahHeap::keep_alive(oop obj) {
1307 if (is_concurrent_mark_in_progress()) {
1308 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1309 }
1310 }
1311
1312 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1313 for (size_t i = 0; i < num_regions(); i++) {
1314 ShenandoahHeapRegion* current = get_region(i);
1315 blk->heap_region_do(current);
1316 }
1317 }
1318
1319 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1320 private:
1321 ShenandoahHeap* const _heap;
1322 ShenandoahHeapRegionClosure* const _blk;
1323
1324 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));
1325 volatile size_t _index;
1326 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
1327
1328 public:
1329 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1330 AbstractGangTask("Parallel Region Task"),
1331 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1332
1333 void work(uint worker_id) {
1334 size_t stride = ShenandoahParallelRegionStride;
1335
1336 size_t max = _heap->num_regions();
1337 while (_index < max) {
1338 size_t cur = Atomic::fetch_and_add(&_index, stride);
1339 size_t start = cur;
1340 size_t end = MIN2(cur + stride, max);
1341 if (start >= max) break;
1342
1343 for (size_t i = cur; i < end; i++) {
1344 ShenandoahHeapRegion* current = _heap->get_region(i);
1345 _blk->heap_region_do(current);
1346 }
1347 }
1348 }
1349 };
1350
1351 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1352 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1353 if (num_regions() > ShenandoahParallelRegionStride) {
1354 ShenandoahParallelHeapRegionTask task(blk);
1355 workers()->run_task(&task);
1356 } else {
1357 heap_region_iterate(blk);
1358 }
1359 }
1360
1361 class ShenandoahClearLivenessClosure : public ShenandoahHeapRegionClosure {
1362 private:
1363 ShenandoahMarkingContext* const _ctx;
1364 public:
1365 ShenandoahClearLivenessClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1366
1367 void heap_region_do(ShenandoahHeapRegion* r) {
1368 if (r->is_active()) {
1369 r->clear_live_data();
1370 _ctx->capture_top_at_mark_start(r);
1371 } else {
1372 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1373 assert(_ctx->top_at_mark_start(r) == r->top(),
1374 "Region " SIZE_FORMAT " should already have correct TAMS", r->region_number());
1375 }
1376 }
1377
1378 bool is_thread_safe() { return true; }
1379 };
1380
1381 void ShenandoahHeap::op_init_mark() {
1382 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1383 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1384
1385 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1386 assert(!marking_context()->is_complete(), "should not be complete");
1387
1388 if (ShenandoahVerify) {
1389 verifier()->verify_before_concmark();
1390 }
1391
1392 if (VerifyBeforeGC) {
1393 Universe::verify();
1394 }
1395
1396 set_concurrent_mark_in_progress(true);
1397 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1398 {
1399 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1400 make_parsable(true);
1401 }
1402
1403 {
1404 ShenandoahGCPhase phase(ShenandoahPhaseTimings::clear_liveness);
1405 ShenandoahClearLivenessClosure clc;
1406 parallel_heap_region_iterate(&clc);
1407 }
1408
1409 // Make above changes visible to worker threads
1410 OrderAccess::fence();
1411
1412 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1413
1414 if (UseTLAB) {
1415 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1416 resize_tlabs();
1417 }
1418
1419 if (ShenandoahPacing) {
1420 pacer()->setup_for_mark();
1421 }
1422 }
1423
1424 void ShenandoahHeap::op_mark() {
1425 concurrent_mark()->mark_from_roots();
1426 }
1427
1428 class ShenandoahCompleteLivenessClosure : public ShenandoahHeapRegionClosure {
1429 private:
1430 ShenandoahMarkingContext* const _ctx;
1431 public:
1432 ShenandoahCompleteLivenessClosure() : _ctx(ShenandoahHeap::heap()->complete_marking_context()) {}
1433
1434 void heap_region_do(ShenandoahHeapRegion* r) {
1435 if (r->is_active()) {
1436 HeapWord *tams = _ctx->top_at_mark_start(r);
1437 HeapWord *top = r->top();
1438 if (top > tams) {
1439 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1440 }
1441 } else {
1442 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1443 assert(_ctx->top_at_mark_start(r) == r->top(),
1444 "Region " SIZE_FORMAT " should have correct TAMS", r->region_number());
1445 }
1446 }
1447
1448 bool is_thread_safe() { return true; }
1449 };
1450
1451 void ShenandoahHeap::op_final_mark() {
1452 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1453
1454 // It is critical that we
1455 // evacuate roots right after finishing marking, so that we don't
1456 // get unmarked objects in the roots.
1457
1458 if (!cancelled_gc()) {
1459 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1460
1461 // Marking is completed, deactivate SATB barrier
1462 set_concurrent_mark_in_progress(false);
1463 mark_complete_marking_context();
1464
1465 parallel_cleaning(false /* full gc*/);
1466
1467 if (has_forwarded_objects()) {
1468 // Degen may be caused by failed evacuation of roots
1469 if (is_degenerated_gc_in_progress()) {
1470 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
1471 } else {
1472 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::update_roots);
1473 }
1474 set_has_forwarded_objects(false);
1475 }
1476
1477 if (ShenandoahVerify) {
1478 verifier()->verify_roots_no_forwarded();
1479 }
1480 // All allocations past TAMS are implicitly live, adjust the region data.
1481 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1482 {
1483 ShenandoahGCPhase phase(ShenandoahPhaseTimings::complete_liveness);
1484 ShenandoahCompleteLivenessClosure cl;
1485 parallel_heap_region_iterate(&cl);
1486 }
1487
1488 // Force the threads to reacquire their TLABs outside the collection set.
1489 {
1490 ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs);
1491 make_parsable(true);
1492 }
1493
1494 // We are about to select the collection set, make sure it knows about
1495 // current pinning status. Also, this allows trashing more regions that
1496 // now have their pinning status dropped.
1497 {
1498 ShenandoahGCPhase phase(ShenandoahPhaseTimings::sync_pinned);
1499 sync_pinned_region_status();
1500 }
1501
1502 // Trash the collection set left over from previous cycle, if any.
1503 {
1504 ShenandoahGCPhase phase(ShenandoahPhaseTimings::trash_cset);
1505 trash_cset_regions();
1506 }
1507
1508 {
1509 ShenandoahGCPhase phase(ShenandoahPhaseTimings::prepare_evac);
1510
1511 ShenandoahHeapLocker locker(lock());
1512 _collection_set->clear();
1513 _free_set->clear();
1514
1515 heuristics()->choose_collection_set(_collection_set);
1516
1517 _free_set->rebuild();
1518 }
1519
1520 if (!is_degenerated_gc_in_progress()) {
1521 prepare_concurrent_roots();
1522 prepare_concurrent_unloading();
1523 }
1524
1525 // If collection set has candidates, start evacuation.
1526 // Otherwise, bypass the rest of the cycle.
1527 if (!collection_set()->is_empty()) {
1528 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1529
1530 if (ShenandoahVerify) {
1531 verifier()->verify_before_evacuation();
1532 }
1533
1534 // Remember limit for updating refs. It's guaranteed that we get no from-space-refs written
1535 // from here on.
1536 for (uint i = 0; i < num_regions(); i++) {
1537 ShenandoahHeapRegion* r = get_region(i);
1538 r->set_update_watermark(r->top());
1539 }
1540
1541 set_evacuation_in_progress(true);
1542 // From here on, we need to update references.
1543 set_has_forwarded_objects(true);
1544
1545 if (!is_degenerated_gc_in_progress()) {
1546 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1547 ShenandoahCodeRoots::arm_nmethods();
1548 }
1549 evacuate_and_update_roots();
1550 }
1551
1552 if (ShenandoahPacing) {
1553 pacer()->setup_for_evac();
1554 }
1555
1556 if (ShenandoahVerify) {
1557 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::None;
1558 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1559 types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots);
1560 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots);
1561 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::StringDedupRoots);
1562 }
1563
1564 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1565 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CodeRoots);
1566 }
1567 verifier()->verify_roots_no_forwarded_except(types);
1568 verifier()->verify_during_evacuation();
1569 }
1570 } else {
1571 if (ShenandoahVerify) {
1572 verifier()->verify_after_concmark();
1573 }
1574
1575 if (VerifyAfterGC) {
1576 Universe::verify();
1577 }
1578 }
1579
1580 } else {
1581 // If this cycle was updating references, we need to keep the has_forwarded_objects
1582 // flag on, for subsequent phases to deal with it.
1583 concurrent_mark()->cancel();
1584 set_concurrent_mark_in_progress(false);
1585
1586 if (process_references()) {
1587 // Abandon reference processing right away: pre-cleaning must have failed.
1588 ReferenceProcessor *rp = ref_processor();
1589 rp->disable_discovery();
1590 rp->abandon_partial_discovery();
1591 rp->verify_no_references_recorded();
1592 }
1593 }
1594 }
1595
1596 void ShenandoahHeap::op_final_evac() {
1597 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1598
1599 set_evacuation_in_progress(false);
1600
1601 {
1602 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_retire_gclabs);
1603 retire_and_reset_gclabs();
1604 }
1605
1606 if (ShenandoahVerify) {
1607 verifier()->verify_after_evacuation();
1608 }
1609
1610 if (VerifyAfterGC) {
1611 Universe::verify();
1612 }
1613 }
1614
1615 void ShenandoahHeap::op_conc_evac() {
1616 ShenandoahEvacuationTask task(this, _collection_set, true);
1617 workers()->run_task(&task);
1618 }
1619
1620 void ShenandoahHeap::op_stw_evac() {
1621 ShenandoahEvacuationTask task(this, _collection_set, false);
1622 workers()->run_task(&task);
1623 }
1624
1625 void ShenandoahHeap::op_updaterefs() {
1626 update_heap_references(true);
1627 }
1628
1629 void ShenandoahHeap::op_cleanup() {
1630 free_set()->recycle_trash();
1631 }
1632
1633 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask {
1634 private:
1635 ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
1636 ShenandoahWeakRoots<true /*concurrent*/> _weak_roots;
1637 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots;
1638 ShenandoahConcurrentStringDedupRoots _dedup_roots;
1639 bool _include_weak_roots;
1640
1641 public:
1642 ShenandoahConcurrentRootsEvacUpdateTask(bool include_weak_roots) :
1643 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Roots Task"),
1644 _include_weak_roots(include_weak_roots) {
1645 }
1646
1647 void work(uint worker_id) {
1648 ShenandoahEvacOOMScope oom;
1649 {
1650 // vm_roots and weak_roots are OopStorage backed roots, concurrent iteration
1651 // may race against OopStorage::release() calls.
1652 ShenandoahEvacUpdateOopStorageRootsClosure cl;
1653 _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1654
1655 if (_include_weak_roots) {
1656 _weak_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1657 }
1658 }
1659
1660 {
1661 ShenandoahEvacuateUpdateRootsClosure<> cl;
1662 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1663 _cld_roots.cld_do(&clds);
1664 }
1665
1666 {
1667 ShenandoahForwardedIsAliveClosure is_alive;
1668 ShenandoahEvacuateUpdateRootsClosure<MO_RELEASE> keep_alive;
1669 _dedup_roots.oops_do(&is_alive, &keep_alive, worker_id);
1670 }
1671 }
1672 };
1673
1674 class ShenandoahEvacUpdateCleanupOopStorageRootsClosure : public BasicOopIterateClosure {
1675 private:
1676 ShenandoahHeap* const _heap;
1677 ShenandoahMarkingContext* const _mark_context;
1678 bool _evac_in_progress;
1679 Thread* const _thread;
1680 size_t _dead_counter;
1681
1682 public:
1683 ShenandoahEvacUpdateCleanupOopStorageRootsClosure();
1684 void do_oop(oop* p);
1685 void do_oop(narrowOop* p);
1686
1687 size_t dead_counter() const;
1688 void reset_dead_counter();
1689 };
1690
1691 ShenandoahEvacUpdateCleanupOopStorageRootsClosure::ShenandoahEvacUpdateCleanupOopStorageRootsClosure() :
1692 _heap(ShenandoahHeap::heap()),
1693 _mark_context(ShenandoahHeap::heap()->marking_context()),
1694 _evac_in_progress(ShenandoahHeap::heap()->is_evacuation_in_progress()),
1695 _thread(Thread::current()),
1696 _dead_counter(0) {
1697 }
1698
1699 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(oop* p) {
1700 const oop obj = RawAccess<>::oop_load(p);
1701 if (!CompressedOops::is_null(obj)) {
1702 if (!_mark_context->is_marked(obj)) {
1703 shenandoah_assert_correct(p, obj);
1704 oop old = Atomic::cmpxchg(p, obj, oop(NULL));
1705 if (obj == old) {
1706 _dead_counter ++;
1707 }
1708 } else if (_evac_in_progress && _heap->in_collection_set(obj)) {
1709 oop resolved = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1710 if (resolved == obj) {
1711 resolved = _heap->evacuate_object(obj, _thread);
1712 }
1713 Atomic::cmpxchg(p, obj, resolved);
1714 assert(_heap->cancelled_gc() ||
1715 _mark_context->is_marked(resolved) && !_heap->in_collection_set(resolved),
1716 "Sanity");
1717 }
1718 }
1719 }
1720
1721 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(narrowOop* p) {
1722 ShouldNotReachHere();
1723 }
1724
1725 size_t ShenandoahEvacUpdateCleanupOopStorageRootsClosure::dead_counter() const {
1726 return _dead_counter;
1727 }
1728
1729 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::reset_dead_counter() {
1730 _dead_counter = 0;
1731 }
1732
1733 // This task not only evacuates/updates marked weak roots, but also "NULL"
1734 // dead weak roots.
1735 class ShenandoahConcurrentWeakRootsEvacUpdateTask : public AbstractGangTask {
1736 private:
1737 ShenandoahWeakRoot<true /*concurrent*/> _jni_roots;
1738 ShenandoahWeakRoot<true /*concurrent*/> _string_table_roots;
1739 ShenandoahWeakRoot<true /*concurrent*/> _resolved_method_table_roots;
1740 ShenandoahWeakRoot<true /*concurrent*/> _vm_roots;
1741
1742 public:
1743 ShenandoahConcurrentWeakRootsEvacUpdateTask() :
1744 AbstractGangTask("Shenandoah Concurrent Weak Root Task"),
1745 _jni_roots(OopStorageSet::jni_weak(), ShenandoahPhaseTimings::JNIWeakRoots),
1746 _string_table_roots(OopStorageSet::string_table_weak(), ShenandoahPhaseTimings::StringTableRoots),
1747 _resolved_method_table_roots(OopStorageSet::resolved_method_table_weak(), ShenandoahPhaseTimings::ResolvedMethodTableRoots),
1748 _vm_roots(OopStorageSet::vm_weak(), ShenandoahPhaseTimings::VMWeakRoots) {
1749 StringTable::reset_dead_counter();
1750 ResolvedMethodTable::reset_dead_counter();
1751 }
1752
1753 ~ShenandoahConcurrentWeakRootsEvacUpdateTask() {
1754 StringTable::finish_dead_counter();
1755 ResolvedMethodTable::finish_dead_counter();
1756 }
1757
1758 void work(uint worker_id) {
1759 ShenandoahEvacOOMScope oom;
1760 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
1761 // may race against OopStorage::release() calls.
1762 ShenandoahEvacUpdateCleanupOopStorageRootsClosure cl;
1763 _jni_roots.oops_do(&cl, worker_id);
1764 _vm_roots.oops_do(&cl, worker_id);
1765
1766 cl.reset_dead_counter();
1767 _string_table_roots.oops_do(&cl, worker_id);
1768 StringTable::inc_dead_counter(cl.dead_counter());
1769
1770 cl.reset_dead_counter();
1771 _resolved_method_table_roots.oops_do(&cl, worker_id);
1772 ResolvedMethodTable::inc_dead_counter(cl.dead_counter());
1773 }
1774 };
1775
1776 void ShenandoahHeap::op_roots() {
1777 if (is_concurrent_root_in_progress()) {
1778 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1779 // Concurrent weak root processing
1780 ShenandoahConcurrentWeakRootsEvacUpdateTask task;
1781 workers()->run_task(&task);
1782
1783 _unloader.unload();
1784 }
1785
1786 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1787 ShenandoahConcurrentRootsEvacUpdateTask task(!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
1788 workers()->run_task(&task);
1789 }
1790 }
1791
1792 set_concurrent_root_in_progress(false);
1793 }
1794
1795 void ShenandoahHeap::op_reset() {
1796 if (ShenandoahPacing) {
1797 pacer()->setup_for_reset();
1798 }
1799 reset_mark_bitmap();
1800 }
1801
1802 void ShenandoahHeap::op_preclean() {
1803 if (ShenandoahPacing) {
1804 pacer()->setup_for_preclean();
1805 }
1806 concurrent_mark()->preclean_weak_refs();
1807 }
1808
1809 void ShenandoahHeap::op_init_traversal() {
1810 traversal_gc()->init_traversal_collection();
1811 }
1812
1813 void ShenandoahHeap::op_traversal() {
1814 traversal_gc()->concurrent_traversal_collection();
1815 }
1816
1817 void ShenandoahHeap::op_final_traversal() {
1818 traversal_gc()->final_traversal_collection();
1819 }
1820
1821 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1822 ShenandoahMetricsSnapshot metrics;
1823 metrics.snap_before();
1824
1825 full_gc()->do_it(cause);
1826 if (UseTLAB) {
1827 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs);
1828 resize_all_tlabs();
1829 }
1830
1831 metrics.snap_after();
1832
1833 if (metrics.is_good_progress()) {
1834 _progress_last_gc.set();
1835 } else {
1836 // Nothing to do. Tell the allocation path that we have failed to make
1837 // progress, and it can finally fail.
1838 _progress_last_gc.unset();
1839 }
1840 }
1841
1842 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1843 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1844 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1845 // some phase, we have to upgrade the Degenerate GC to Full GC.
1846
1847 clear_cancelled_gc();
1848
1849 ShenandoahMetricsSnapshot metrics;
1850 metrics.snap_before();
1851
1852 switch (point) {
1853 case _degenerated_traversal:
1854 {
1855 // Drop the collection set. Note: this leaves some already forwarded objects
1856 // behind, which may be problematic, see comments for ShenandoahEvacAssist
1857 // workarounds in ShenandoahTraversalHeuristics.
1858
1859 ShenandoahHeapLocker locker(lock());
1860 collection_set()->clear_current_index();
1861 for (size_t i = 0; i < collection_set()->count(); i++) {
1862 ShenandoahHeapRegion* r = collection_set()->next();
1863 r->make_regular_bypass();
1864 }
1865 collection_set()->clear();
1866 }
1867 op_final_traversal();
1868 op_cleanup();
1869 return;
1870
1871 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1872 // but enters it at different points, depending on which concurrent phase had
1873 // degenerated.
1874
1875 case _degenerated_outside_cycle:
1876 // We have degenerated from outside the cycle, which means something is bad with
1877 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1878 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1879 // we can do the most aggressive degen cycle, which includes processing references and
1880 // class unloading, unless those features are explicitly disabled.
1881 //
1882 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1883 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1884 set_process_references(heuristics()->can_process_references());
1885 set_unload_classes(heuristics()->can_unload_classes());
1886
1887 if (is_traversal_mode()) {
1888 // Not possible to degenerate from here, upgrade to Full GC right away.
1889 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1890 op_degenerated_fail();
1891 return;
1892 }
1893
1894 op_reset();
1895
1896 op_init_mark();
1897 if (cancelled_gc()) {
1898 op_degenerated_fail();
1899 return;
1900 }
1901
1902 case _degenerated_mark:
1903 op_final_mark();
1904 if (cancelled_gc()) {
1905 op_degenerated_fail();
1906 return;
1907 }
1908
1909 op_cleanup();
1910
1911 case _degenerated_evac:
1912 // If heuristics thinks we should do the cycle, this flag would be set,
1913 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
1914 if (is_evacuation_in_progress()) {
1915
1916 // Degeneration under oom-evac protocol might have left some objects in
1917 // collection set un-evacuated. Restart evacuation from the beginning to
1918 // capture all objects. For all the objects that are already evacuated,
1919 // it would be a simple check, which is supposed to be fast. This is also
1920 // safe to do even without degeneration, as CSet iterator is at beginning
1921 // in preparation for evacuation anyway.
1922 //
1923 // Before doing that, we need to make sure we never had any cset-pinned
1924 // regions. This may happen if allocation failure happened when evacuating
1925 // the about-to-be-pinned object, oom-evac protocol left the object in
1926 // the collection set, and then the pin reached the cset region. If we continue
1927 // the cycle here, we would trash the cset and alive objects in it. To avoid
1928 // it, we fail degeneration right away and slide into Full GC to recover.
1929
1930 {
1931 sync_pinned_region_status();
1932 collection_set()->clear_current_index();
1933
1934 ShenandoahHeapRegion* r;
1935 while ((r = collection_set()->next()) != NULL) {
1936 if (r->is_pinned()) {
1937 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1938 op_degenerated_fail();
1939 return;
1940 }
1941 }
1942
1943 collection_set()->clear_current_index();
1944 }
1945
1946 op_stw_evac();
1947 if (cancelled_gc()) {
1948 op_degenerated_fail();
1949 return;
1950 }
1951 }
1952
1953 // If heuristics thinks we should do the cycle, this flag would be set,
1954 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
1955 if (has_forwarded_objects()) {
1956 op_init_updaterefs();
1957 if (cancelled_gc()) {
1958 op_degenerated_fail();
1959 return;
1960 }
1961 }
1962
1963 case _degenerated_updaterefs:
1964 if (has_forwarded_objects()) {
1965 op_final_updaterefs();
1966 if (cancelled_gc()) {
1967 op_degenerated_fail();
1968 return;
1969 }
1970 }
1971
1972 op_cleanup();
1973 break;
1974
1975 default:
1976 ShouldNotReachHere();
1977 }
1978
1979 if (ShenandoahVerify) {
1980 verifier()->verify_after_degenerated();
1981 }
1982
1983 if (VerifyAfterGC) {
1984 Universe::verify();
1985 }
1986
1987 metrics.snap_after();
1988
1989 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
1990 // because that probably means the heap is overloaded and/or fragmented.
1991 if (!metrics.is_good_progress()) {
1992 _progress_last_gc.unset();
1993 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1994 op_degenerated_futile();
1995 } else {
1996 _progress_last_gc.set();
1997 }
1998 }
1999
2000 void ShenandoahHeap::op_degenerated_fail() {
2001 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
2002 shenandoah_policy()->record_degenerated_upgrade_to_full();
2003 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2004 }
2005
2006 void ShenandoahHeap::op_degenerated_futile() {
2007 shenandoah_policy()->record_degenerated_upgrade_to_full();
2008 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2009 }
2010
2011 void ShenandoahHeap::force_satb_flush_all_threads() {
2012 if (!is_concurrent_mark_in_progress() && !is_concurrent_traversal_in_progress()) {
2013 // No need to flush SATBs
2014 return;
2015 }
2016
2017 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2018 ShenandoahThreadLocalData::set_force_satb_flush(t, true);
2019 }
2020 // The threads are not "acquiring" their thread-local data, but it does not
2021 // hurt to "release" the updates here anyway.
2022 OrderAccess::fence();
2023 }
2024
2025 void ShenandoahHeap::set_gc_state_all_threads(char state) {
2026 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2027 ShenandoahThreadLocalData::set_gc_state(t, state);
2028 }
2029 }
2030
2031 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
2032 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
2033 _gc_state.set_cond(mask, value);
2034 set_gc_state_all_threads(_gc_state.raw_value());
2035 }
2036
2037 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
2038 if (has_forwarded_objects()) {
2039 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
2040 } else {
2041 set_gc_state_mask(MARKING, in_progress);
2042 }
2043 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
2044 }
2045
2046 void ShenandoahHeap::set_concurrent_traversal_in_progress(bool in_progress) {
2047 set_gc_state_mask(TRAVERSAL, in_progress);
2048 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
2049 }
2050
2051 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
2052 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
2053 set_gc_state_mask(EVACUATION, in_progress);
2054 }
2055
2056 void ShenandoahHeap::set_concurrent_root_in_progress(bool in_progress) {
2057 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
2058 if (in_progress) {
2059 _concurrent_root_in_progress.set();
2060 } else {
2061 _concurrent_root_in_progress.unset();
2062 }
2063 }
2064
2065 void ShenandoahHeap::ref_processing_init() {
2066 assert(_max_workers > 0, "Sanity");
2067
2068 _ref_processor =
2069 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
2070 ParallelRefProcEnabled, // MT processing
2071 _max_workers, // Degree of MT processing
2072 true, // MT discovery
2073 _max_workers, // Degree of MT discovery
2074 false, // Reference discovery is not atomic
2075 NULL, // No closure, should be installed before use
2076 true); // Scale worker threads
2077
2078 shenandoah_assert_rp_isalive_not_installed();
2079 }
2080
2081 GCTracer* ShenandoahHeap::tracer() {
2082 return shenandoah_policy()->tracer();
2083 }
2084
2085 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
2086 return _free_set->used();
2087 }
2088
2089 bool ShenandoahHeap::try_cancel_gc() {
2090 while (true) {
2091 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
2092 if (prev == CANCELLABLE) return true;
2093 else if (prev == CANCELLED) return false;
2094 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
2095 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
2096 if (Thread::current()->is_Java_thread()) {
2097 // We need to provide a safepoint here, otherwise we might
2098 // spin forever if a SP is pending.
2099 ThreadBlockInVM sp(JavaThread::current());
2100 SpinPause();
2101 }
2102 }
2103 }
2104
2105 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
2106 if (try_cancel_gc()) {
2107 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
2108 log_info(gc)("%s", msg.buffer());
2109 Events::log(Thread::current(), "%s", msg.buffer());
2110 }
2111 }
2112
2113 uint ShenandoahHeap::max_workers() {
2114 return _max_workers;
2115 }
2116
2117 void ShenandoahHeap::stop() {
2118 // The shutdown sequence should be able to terminate when GC is running.
2119
2120 // Step 0. Notify policy to disable event recording.
2121 _shenandoah_policy->record_shutdown();
2122
2123 // Step 1. Notify control thread that we are in shutdown.
2124 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
2125 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
2126 control_thread()->prepare_for_graceful_shutdown();
2127
2128 // Step 2. Notify GC workers that we are cancelling GC.
2129 cancel_gc(GCCause::_shenandoah_stop_vm);
2130
2131 // Step 3. Wait until GC worker exits normally.
2132 control_thread()->stop();
2133
2134 // Step 4. Stop String Dedup thread if it is active
2135 if (ShenandoahStringDedup::is_enabled()) {
2136 ShenandoahStringDedup::stop();
2137 }
2138 }
2139
2140 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
2141 if (!unload_classes()) return;
2142 bool purged_class;
2143
2144 // Unload classes and purge SystemDictionary.
2145 {
2146 ShenandoahGCPhase phase(full_gc ?
2147 ShenandoahPhaseTimings::full_gc_purge_class_unload :
2148 ShenandoahPhaseTimings::purge_class_unload);
2149 purged_class = SystemDictionary::do_unloading(gc_timer());
2150 }
2151
2152 {
2153 ShenandoahGCPhase phase(full_gc ?
2154 ShenandoahPhaseTimings::full_gc_purge_par :
2155 ShenandoahPhaseTimings::purge_par);
2156 ShenandoahIsAliveSelector is_alive;
2157 uint num_workers = _workers->active_workers();
2158 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
2159 _workers->run_task(&unlink_task);
2160 }
2161
2162 {
2163 ShenandoahGCPhase phase(full_gc ?
2164 ShenandoahPhaseTimings::full_gc_purge_cldg :
2165 ShenandoahPhaseTimings::purge_cldg);
2166 ClassLoaderDataGraph::purge();
2167 }
2168 // Resize and verify metaspace
2169 MetaspaceGC::compute_new_size();
2170 MetaspaceUtils::verify_metrics();
2171 }
2172
2173 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
2174 // so they should not have forwarded oops.
2175 // However, we do need to "null" dead oops in the roots, if can not be done
2176 // in concurrent cycles.
2177 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
2178 ShenandoahGCPhase root_phase(full_gc ?
2179 ShenandoahPhaseTimings::full_gc_purge :
2180 ShenandoahPhaseTimings::purge);
2181 uint num_workers = _workers->active_workers();
2182 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
2183 ShenandoahPhaseTimings::full_gc_purge_par :
2184 ShenandoahPhaseTimings::purge_par;
2185 ShenandoahGCPhase phase(timing_phase);
2186 ShenandoahGCWorkerPhase worker_phase(timing_phase);
2187
2188 // Cleanup weak roots
2189 if (has_forwarded_objects()) {
2190 ShenandoahForwardedIsAliveClosure is_alive;
2191 ShenandoahUpdateRefsClosure keep_alive;
2192 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2193 cleaning_task(&is_alive, &keep_alive, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2194 _workers->run_task(&cleaning_task);
2195 } else {
2196 ShenandoahIsAliveClosure is_alive;
2197 #ifdef ASSERT
2198 ShenandoahAssertNotForwardedClosure verify_cl;
2199 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2200 cleaning_task(&is_alive, &verify_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2201 #else
2202 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2203 cleaning_task(&is_alive, &do_nothing_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2204 #endif
2205 _workers->run_task(&cleaning_task);
2206 }
2207 }
2208
2209 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2210 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2211 stw_process_weak_roots(full_gc);
2212 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2213 stw_unload_classes(full_gc);
2214 }
2215 }
2216
2217 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2218 if (is_traversal_mode()) {
2219 set_gc_state_mask(HAS_FORWARDED | UPDATEREFS, cond);
2220 } else {
2221 set_gc_state_mask(HAS_FORWARDED, cond);
2222 }
2223
2224 }
2225
2226 void ShenandoahHeap::set_process_references(bool pr) {
2227 _process_references.set_cond(pr);
2228 }
2229
2230 void ShenandoahHeap::set_unload_classes(bool uc) {
2231 _unload_classes.set_cond(uc);
2232 }
2233
2234 bool ShenandoahHeap::process_references() const {
2235 return _process_references.is_set();
2236 }
2237
2238 bool ShenandoahHeap::unload_classes() const {
2239 return _unload_classes.is_set();
2240 }
2241
2242 address ShenandoahHeap::in_cset_fast_test_addr() {
2243 ShenandoahHeap* heap = ShenandoahHeap::heap();
2244 assert(heap->collection_set() != NULL, "Sanity");
2245 return (address) heap->collection_set()->biased_map_address();
2246 }
2247
2248 address ShenandoahHeap::cancelled_gc_addr() {
2249 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
2250 }
2251
2252 address ShenandoahHeap::gc_state_addr() {
2253 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2254 }
2255
2256 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2257 return Atomic::load_acquire(&_bytes_allocated_since_gc_start);
2258 }
2259
2260 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2261 Atomic::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2262 }
2263
2264 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2265 _degenerated_gc_in_progress.set_cond(in_progress);
2266 }
2267
2268 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2269 _full_gc_in_progress.set_cond(in_progress);
2270 }
2271
2272 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2273 assert (is_full_gc_in_progress(), "should be");
2274 _full_gc_move_in_progress.set_cond(in_progress);
2275 }
2276
2277 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2278 set_gc_state_mask(UPDATEREFS, in_progress);
2279 }
2280
2281 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2282 ShenandoahCodeRoots::register_nmethod(nm);
2283 }
2284
2285 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2286 ShenandoahCodeRoots::unregister_nmethod(nm);
2287 }
2288
2289 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
2290 ShenandoahCodeRoots::flush_nmethod(nm);
2291 }
2292
2293 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2294 heap_region_containing(o)->record_pin();
2295 return o;
2296 }
2297
2298 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2299 heap_region_containing(o)->record_unpin();
2300 }
2301
2302 void ShenandoahHeap::sync_pinned_region_status() {
2303 ShenandoahHeapLocker locker(lock());
2304
2305 for (size_t i = 0; i < num_regions(); i++) {
2306 ShenandoahHeapRegion *r = get_region(i);
2307 if (r->is_active()) {
2308 if (r->is_pinned()) {
2309 if (r->pin_count() == 0) {
2310 r->make_unpinned();
2311 }
2312 } else {
2313 if (r->pin_count() > 0) {
2314 r->make_pinned();
2315 }
2316 }
2317 }
2318 }
2319
2320 assert_pinned_region_status();
2321 }
2322
2323 #ifdef ASSERT
2324 void ShenandoahHeap::assert_pinned_region_status() {
2325 for (size_t i = 0; i < num_regions(); i++) {
2326 ShenandoahHeapRegion* r = get_region(i);
2327 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2328 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2329 }
2330 }
2331 #endif
2332
2333 GCTimer* ShenandoahHeap::gc_timer() const {
2334 return _gc_timer;
2335 }
2336
2337 void ShenandoahHeap::prepare_concurrent_roots() {
2338 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2339 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
2340 set_concurrent_root_in_progress(true);
2341 }
2342 }
2343
2344 void ShenandoahHeap::prepare_concurrent_unloading() {
2345 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2346 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2347 _unloader.prepare();
2348 }
2349 }
2350
2351 void ShenandoahHeap::finish_concurrent_unloading() {
2352 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2353 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2354 _unloader.finish();
2355 }
2356 }
2357
2358 #ifdef ASSERT
2359 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2360 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2361
2362 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2363 if (UseDynamicNumberOfGCThreads ||
2364 (FLAG_IS_DEFAULT(ParallelGCThreads) && ForceDynamicNumberOfGCThreads)) {
2365 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2366 } else {
2367 // Use ParallelGCThreads inside safepoints
2368 assert(nworkers == ParallelGCThreads, "Use ParalleGCThreads within safepoints");
2369 }
2370 } else {
2371 if (UseDynamicNumberOfGCThreads ||
2372 (FLAG_IS_DEFAULT(ConcGCThreads) && ForceDynamicNumberOfGCThreads)) {
2373 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2374 } else {
2375 // Use ConcGCThreads outside safepoints
2376 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2377 }
2378 }
2379 }
2380 #endif
2381
2382 ShenandoahVerifier* ShenandoahHeap::verifier() {
2383 guarantee(ShenandoahVerify, "Should be enabled");
2384 assert (_verifier != NULL, "sanity");
2385 return _verifier;
2386 }
2387
2388 template<class T>
2389 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2390 private:
2391 T cl;
2392 ShenandoahHeap* _heap;
2393 ShenandoahRegionIterator* _regions;
2394 bool _concurrent;
2395 public:
2396 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2397 AbstractGangTask("Concurrent Update References Task"),
2398 cl(T()),
2399 _heap(ShenandoahHeap::heap()),
2400 _regions(regions),
2401 _concurrent(concurrent) {
2402 }
2403
2404 void work(uint worker_id) {
2405 if (_concurrent) {
2406 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2407 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2408 do_work();
2409 } else {
2410 ShenandoahParallelWorkerSession worker_session(worker_id);
2411 do_work();
2412 }
2413 }
2414
2415 private:
2416 void do_work() {
2417 ShenandoahHeapRegion* r = _regions->next();
2418 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2419 while (r != NULL) {
2420 HeapWord* update_watermark = r->get_update_watermark();
2421 assert (update_watermark >= r->bottom(), "sanity");
2422 if (r->is_active() && !r->is_cset()) {
2423 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2424 }
2425 if (ShenandoahPacing) {
2426 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2427 }
2428 if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
2429 return;
2430 }
2431 r = _regions->next();
2432 }
2433 }
2434 };
2435
2436 void ShenandoahHeap::update_heap_references(bool concurrent) {
2437 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
2438 workers()->run_task(&task);
2439 }
2440
2441 void ShenandoahHeap::op_init_updaterefs() {
2442 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2443
2444 set_evacuation_in_progress(false);
2445
2446 {
2447 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_retire_gclabs);
2448 retire_and_reset_gclabs();
2449 }
2450
2451 if (ShenandoahVerify) {
2452 if (!is_degenerated_gc_in_progress()) {
2453 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2454 }
2455 verifier()->verify_before_updaterefs();
2456 }
2457
2458 set_update_refs_in_progress(true);
2459
2460 {
2461 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_prepare);
2462
2463 make_parsable(true);
2464
2465 // Reset iterator.
2466 _update_refs_iterator.reset();
2467 }
2468
2469 if (ShenandoahPacing) {
2470 pacer()->setup_for_updaterefs();
2471 }
2472 }
2473
2474 void ShenandoahHeap::op_final_updaterefs() {
2475 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2476
2477 finish_concurrent_unloading();
2478
2479 // Check if there is left-over work, and finish it
2480 if (_update_refs_iterator.has_next()) {
2481 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2482
2483 // Finish updating references where we left off.
2484 clear_cancelled_gc();
2485 update_heap_references(false);
2486 }
2487
2488 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2489 // everything. On degenerated paths, cancelled gc would not be set anyway.
2490 if (cancelled_gc()) {
2491 clear_cancelled_gc();
2492 }
2493 assert(!cancelled_gc(), "Should have been done right before");
2494
2495 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2496 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2497 }
2498
2499 if (is_degenerated_gc_in_progress()) {
2500 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2501 } else {
2502 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2503 }
2504
2505 // Has to be done before cset is clear
2506 if (ShenandoahVerify) {
2507 verifier()->verify_roots_in_to_space();
2508 }
2509
2510 // Drop unnecessary "pinned" state from regions that does not have CP marks
2511 // anymore, as this would allow trashing them below.
2512 {
2513 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_sync_pinned);
2514 sync_pinned_region_status();
2515 }
2516
2517 {
2518 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2519 trash_cset_regions();
2520 }
2521
2522 set_has_forwarded_objects(false);
2523 set_update_refs_in_progress(false);
2524
2525 if (ShenandoahVerify) {
2526 verifier()->verify_after_updaterefs();
2527 }
2528
2529 if (VerifyAfterGC) {
2530 Universe::verify();
2531 }
2532
2533 {
2534 ShenandoahHeapLocker locker(lock());
2535 _free_set->rebuild();
2536 }
2537 }
2538
2539 #ifdef ASSERT
2540 void ShenandoahHeap::assert_heaplock_owned_by_current_thread() {
2541 _lock.assert_owned_by_current_thread();
2542 }
2543
2544 void ShenandoahHeap::assert_heaplock_not_owned_by_current_thread() {
2545 _lock.assert_not_owned_by_current_thread();
2546 }
2547
2548 void ShenandoahHeap::assert_heaplock_or_safepoint() {
2549 _lock.assert_owned_by_current_thread_or_safepoint();
2550 }
2551 #endif
2552
2553 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2554 print_on(st);
2555 print_heap_regions_on(st);
2556 }
2557
2558 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2559 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2560
2561 size_t regions_from = _bitmap_regions_per_slice * slice;
2562 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2563 for (size_t g = regions_from; g < regions_to; g++) {
2564 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2565 if (skip_self && g == r->region_number()) continue;
2566 if (get_region(g)->is_committed()) {
2567 return true;
2568 }
2569 }
2570 return false;
2571 }
2572
2573 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2574 assert_heaplock_owned_by_current_thread();
2575
2576 // Bitmaps in special regions do not need commits
2577 if (_bitmap_region_special) {
2578 return true;
2579 }
2580
2581 if (is_bitmap_slice_committed(r, true)) {
2582 // Some other region from the group is already committed, meaning the bitmap
2583 // slice is already committed, we exit right away.
2584 return true;
2585 }
2586
2587 // Commit the bitmap slice:
2588 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2589 size_t off = _bitmap_bytes_per_slice * slice;
2590 size_t len = _bitmap_bytes_per_slice;
2591 if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) {
2592 return false;
2593 }
2594 return true;
2595 }
2596
2597 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2598 assert_heaplock_owned_by_current_thread();
2599
2600 // Bitmaps in special regions do not need uncommits
2601 if (_bitmap_region_special) {
2602 return true;
2603 }
2604
2605 if (is_bitmap_slice_committed(r, true)) {
2606 // Some other region from the group is still committed, meaning the bitmap
2607 // slice is should stay committed, exit right away.
2608 return true;
2609 }
2610
2611 // Uncommit the bitmap slice:
2612 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2613 size_t off = _bitmap_bytes_per_slice * slice;
2614 size_t len = _bitmap_bytes_per_slice;
2615 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2616 return false;
2617 }
2618 return true;
2619 }
2620
2621 void ShenandoahHeap::safepoint_synchronize_begin() {
2622 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2623 SuspendibleThreadSet::synchronize();
2624 }
2625 }
2626
2627 void ShenandoahHeap::safepoint_synchronize_end() {
2628 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2629 SuspendibleThreadSet::desynchronize();
2630 }
2631 }
2632
2633 void ShenandoahHeap::vmop_entry_init_mark() {
2634 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2635 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2636 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
2637
2638 try_inject_alloc_failure();
2639 VM_ShenandoahInitMark op;
2640 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2641 }
2642
2643 void ShenandoahHeap::vmop_entry_final_mark() {
2644 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2645 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2646 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
2647
2648 try_inject_alloc_failure();
2649 VM_ShenandoahFinalMarkStartEvac op;
2650 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2651 }
2652
2653 void ShenandoahHeap::vmop_entry_final_evac() {
2654 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2655 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2656 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_gross);
2657
2658 VM_ShenandoahFinalEvac op;
2659 VMThread::execute(&op); // jump to entry_final_evac under safepoint
2660 }
2661
2662 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2663 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2664 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2665 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
2666
2667 try_inject_alloc_failure();
2668 VM_ShenandoahInitUpdateRefs op;
2669 VMThread::execute(&op);
2670 }
2671
2672 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2673 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2674 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2675 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
2676
2677 try_inject_alloc_failure();
2678 VM_ShenandoahFinalUpdateRefs op;
2679 VMThread::execute(&op);
2680 }
2681
2682 void ShenandoahHeap::vmop_entry_init_traversal() {
2683 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2684 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2685 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc_gross);
2686
2687 try_inject_alloc_failure();
2688 VM_ShenandoahInitTraversalGC op;
2689 VMThread::execute(&op);
2690 }
2691
2692 void ShenandoahHeap::vmop_entry_final_traversal() {
2693 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2694 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2695 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc_gross);
2696
2697 try_inject_alloc_failure();
2698 VM_ShenandoahFinalTraversalGC op;
2699 VMThread::execute(&op);
2700 }
2701
2702 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2703 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2704 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2705 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
2706
2707 try_inject_alloc_failure();
2708 VM_ShenandoahFullGC op(cause);
2709 VMThread::execute(&op);
2710 }
2711
2712 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2713 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2714 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2715 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
2716
2717 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2718 VMThread::execute(°enerated_gc);
2719 }
2720
2721 void ShenandoahHeap::entry_init_mark() {
2722 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2723 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
2724 const char* msg = init_mark_event_message();
2725 GCTraceTime(Info, gc) time(msg, gc_timer());
2726 EventMark em("%s", msg);
2727
2728 ShenandoahWorkerScope scope(workers(),
2729 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2730 "init marking");
2731
2732 op_init_mark();
2733 }
2734
2735 void ShenandoahHeap::entry_final_mark() {
2736 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2737 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
2738 const char* msg = final_mark_event_message();
2739 GCTraceTime(Info, gc) time(msg, gc_timer());
2740 EventMark em("%s", msg);
2741
2742 ShenandoahWorkerScope scope(workers(),
2743 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2744 "final marking");
2745
2746 op_final_mark();
2747 }
2748
2749 void ShenandoahHeap::entry_final_evac() {
2750 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2751 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac);
2752 static const char* msg = "Pause Final Evac";
2753 GCTraceTime(Info, gc) time(msg, gc_timer());
2754 EventMark em("%s", msg);
2755
2756 op_final_evac();
2757 }
2758
2759 void ShenandoahHeap::entry_init_updaterefs() {
2760 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2761 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
2762
2763 static const char* msg = "Pause Init Update Refs";
2764 GCTraceTime(Info, gc) time(msg, gc_timer());
2765 EventMark em("%s", msg);
2766
2767 // No workers used in this phase, no setup required
2768
2769 op_init_updaterefs();
2770 }
2771
2772 void ShenandoahHeap::entry_final_updaterefs() {
2773 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2774 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
2775
2776 static const char* msg = "Pause Final Update Refs";
2777 GCTraceTime(Info, gc) time(msg, gc_timer());
2778 EventMark em("%s", msg);
2779
2780 ShenandoahWorkerScope scope(workers(),
2781 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2782 "final reference update");
2783
2784 op_final_updaterefs();
2785 }
2786
2787 void ShenandoahHeap::entry_init_traversal() {
2788 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2789 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc);
2790
2791 static const char* msg = init_traversal_event_message();
2792 GCTraceTime(Info, gc) time(msg, gc_timer());
2793 EventMark em("%s", msg);
2794
2795 ShenandoahWorkerScope scope(workers(),
2796 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2797 "init traversal");
2798
2799 op_init_traversal();
2800 }
2801
2802 void ShenandoahHeap::entry_final_traversal() {
2803 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2804 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc);
2805
2806 static const char* msg = final_traversal_event_message();
2807 GCTraceTime(Info, gc) time(msg, gc_timer());
2808 EventMark em("%s", msg);
2809
2810 ShenandoahWorkerScope scope(workers(),
2811 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2812 "final traversal");
2813
2814 op_final_traversal();
2815 }
2816
2817 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2818 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2819 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
2820
2821 static const char* msg = "Pause Full";
2822 GCTraceTime(Info, gc) time(msg, gc_timer(), cause, true);
2823 EventMark em("%s", msg);
2824
2825 ShenandoahWorkerScope scope(workers(),
2826 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2827 "full gc");
2828
2829 op_full(cause);
2830 }
2831
2832 void ShenandoahHeap::entry_degenerated(int point) {
2833 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2834 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
2835
2836 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2837 const char* msg = degen_event_message(dpoint);
2838 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2839 EventMark em("%s", msg);
2840
2841 ShenandoahWorkerScope scope(workers(),
2842 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2843 "stw degenerated gc");
2844
2845 set_degenerated_gc_in_progress(true);
2846 op_degenerated(dpoint);
2847 set_degenerated_gc_in_progress(false);
2848 }
2849
2850 void ShenandoahHeap::entry_mark() {
2851 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2852
2853 const char* msg = conc_mark_event_message();
2854 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2855 EventMark em("%s", msg);
2856
2857 ShenandoahWorkerScope scope(workers(),
2858 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2859 "concurrent marking");
2860
2861 try_inject_alloc_failure();
2862 op_mark();
2863 }
2864
2865 void ShenandoahHeap::entry_evac() {
2866 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
2867 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2868
2869 static const char* msg = "Concurrent evacuation";
2870 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2871 EventMark em("%s", msg);
2872
2873 ShenandoahWorkerScope scope(workers(),
2874 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2875 "concurrent evacuation");
2876
2877 try_inject_alloc_failure();
2878 op_conc_evac();
2879 }
2880
2881 void ShenandoahHeap::entry_updaterefs() {
2882 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
2883
2884 static const char* msg = "Concurrent update references";
2885 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2886 EventMark em("%s", msg);
2887
2888 ShenandoahWorkerScope scope(workers(),
2889 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2890 "concurrent reference update");
2891
2892 try_inject_alloc_failure();
2893 op_updaterefs();
2894 }
2895
2896 void ShenandoahHeap::entry_roots() {
2897 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_roots);
2898
2899 static const char* msg = "Concurrent roots processing";
2900 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2901 EventMark em("%s", msg);
2902
2903 ShenandoahWorkerScope scope(workers(),
2904 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2905 "concurrent root processing");
2906
2907 try_inject_alloc_failure();
2908 op_roots();
2909 }
2910
2911 void ShenandoahHeap::entry_cleanup() {
2912 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup);
2913
2914 static const char* msg = "Concurrent cleanup";
2915 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2916 EventMark em("%s", msg);
2917
2918 // This phase does not use workers, no need for setup
2919
2920 try_inject_alloc_failure();
2921 op_cleanup();
2922 }
2923
2924 void ShenandoahHeap::entry_reset() {
2925 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset);
2926
2927 static const char* msg = "Concurrent reset";
2928 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2929 EventMark em("%s", msg);
2930
2931 ShenandoahWorkerScope scope(workers(),
2932 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2933 "concurrent reset");
2934
2935 try_inject_alloc_failure();
2936 op_reset();
2937 }
2938
2939 void ShenandoahHeap::entry_preclean() {
2940 if (ShenandoahPreclean && process_references()) {
2941 static const char* msg = "Concurrent precleaning";
2942 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2943 EventMark em("%s", msg);
2944
2945 ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
2946
2947 ShenandoahWorkerScope scope(workers(),
2948 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2949 "concurrent preclean",
2950 /* check_workers = */ false);
2951
2952 try_inject_alloc_failure();
2953 op_preclean();
2954 }
2955 }
2956
2957 void ShenandoahHeap::entry_traversal() {
2958 static const char* msg = conc_traversal_event_message();
2959 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2960 EventMark em("%s", msg);
2961
2962 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2963
2964 ShenandoahWorkerScope scope(workers(),
2965 ShenandoahWorkerPolicy::calc_workers_for_conc_traversal(),
2966 "concurrent traversal");
2967
2968 try_inject_alloc_failure();
2969 op_traversal();
2970 }
2971
2972 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2973 static const char *msg = "Concurrent uncommit";
2974 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2975 EventMark em("%s", msg);
2976
2977 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit);
2978
2979 op_uncommit(shrink_before);
2980 }
2981
2982 void ShenandoahHeap::try_inject_alloc_failure() {
2983 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2984 _inject_alloc_failure.set();
2985 os::naked_short_sleep(1);
2986 if (cancelled_gc()) {
2987 log_info(gc)("Allocation failure was successfully injected");
2988 }
2989 }
2990 }
2991
2992 bool ShenandoahHeap::should_inject_alloc_failure() {
2993 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2994 }
2995
2996 void ShenandoahHeap::initialize_serviceability() {
2997 _memory_pool = new ShenandoahMemoryPool(this);
2998 _cycle_memory_manager.add_pool(_memory_pool);
2999 _stw_memory_manager.add_pool(_memory_pool);
3000 }
3001
3002 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
3003 GrowableArray<GCMemoryManager*> memory_managers(2);
3004 memory_managers.append(&_cycle_memory_manager);
3005 memory_managers.append(&_stw_memory_manager);
3006 return memory_managers;
3007 }
3008
3009 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
3010 GrowableArray<MemoryPool*> memory_pools(1);
3011 memory_pools.append(_memory_pool);
3012 return memory_pools;
3013 }
3014
3015 MemoryUsage ShenandoahHeap::memory_usage() {
3016 return _memory_pool->get_memory_usage();
3017 }
3018
3019 void ShenandoahHeap::enter_evacuation() {
3020 _oom_evac_handler.enter_evacuation();
3021 }
3022
3023 void ShenandoahHeap::leave_evacuation() {
3024 _oom_evac_handler.leave_evacuation();
3025 }
3026
3027 ShenandoahRegionIterator::ShenandoahRegionIterator() :
3028 _heap(ShenandoahHeap::heap()),
3029 _index(0) {}
3030
3031 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
3032 _heap(heap),
3033 _index(0) {}
3034
3035 void ShenandoahRegionIterator::reset() {
3036 _index = 0;
3037 }
3038
3039 bool ShenandoahRegionIterator::has_next() const {
3040 return _index < _heap->num_regions();
3041 }
3042
3043 char ShenandoahHeap::gc_state() const {
3044 return _gc_state.raw_value();
3045 }
3046
3047 void ShenandoahHeap::deduplicate_string(oop str) {
3048 assert(java_lang_String::is_instance(str), "invariant");
3049
3050 if (ShenandoahStringDedup::is_enabled()) {
3051 ShenandoahStringDedup::deduplicate(str);
3052 }
3053 }
3054
3055 const char* ShenandoahHeap::init_mark_event_message() const {
3056 bool update_refs = has_forwarded_objects();
3057 bool proc_refs = process_references();
3058 bool unload_cls = unload_classes();
3059
3060 if (update_refs && proc_refs && unload_cls) {
3061 return "Pause Init Mark (update refs) (process weakrefs) (unload classes)";
3062 } else if (update_refs && proc_refs) {
3063 return "Pause Init Mark (update refs) (process weakrefs)";
3064 } else if (update_refs && unload_cls) {
3065 return "Pause Init Mark (update refs) (unload classes)";
3066 } else if (proc_refs && unload_cls) {
3067 return "Pause Init Mark (process weakrefs) (unload classes)";
3068 } else if (update_refs) {
3069 return "Pause Init Mark (update refs)";
3070 } else if (proc_refs) {
3071 return "Pause Init Mark (process weakrefs)";
3072 } else if (unload_cls) {
3073 return "Pause Init Mark (unload classes)";
3074 } else {
3075 return "Pause Init Mark";
3076 }
3077 }
3078
3079 const char* ShenandoahHeap::final_mark_event_message() const {
3080 bool update_refs = has_forwarded_objects();
3081 bool proc_refs = process_references();
3082 bool unload_cls = unload_classes();
3083
3084 if (update_refs && proc_refs && unload_cls) {
3085 return "Pause Final Mark (update refs) (process weakrefs) (unload classes)";
3086 } else if (update_refs && proc_refs) {
3087 return "Pause Final Mark (update refs) (process weakrefs)";
3088 } else if (update_refs && unload_cls) {
3089 return "Pause Final Mark (update refs) (unload classes)";
3090 } else if (proc_refs && unload_cls) {
3091 return "Pause Final Mark (process weakrefs) (unload classes)";
3092 } else if (update_refs) {
3093 return "Pause Final Mark (update refs)";
3094 } else if (proc_refs) {
3095 return "Pause Final Mark (process weakrefs)";
3096 } else if (unload_cls) {
3097 return "Pause Final Mark (unload classes)";
3098 } else {
3099 return "Pause Final Mark";
3100 }
3101 }
3102
3103 const char* ShenandoahHeap::conc_mark_event_message() const {
3104 bool update_refs = has_forwarded_objects();
3105 bool proc_refs = process_references();
3106 bool unload_cls = unload_classes();
3107
3108 if (update_refs && proc_refs && unload_cls) {
3109 return "Concurrent marking (update refs) (process weakrefs) (unload classes)";
3110 } else if (update_refs && proc_refs) {
3111 return "Concurrent marking (update refs) (process weakrefs)";
3112 } else if (update_refs && unload_cls) {
3113 return "Concurrent marking (update refs) (unload classes)";
3114 } else if (proc_refs && unload_cls) {
3115 return "Concurrent marking (process weakrefs) (unload classes)";
3116 } else if (update_refs) {
3117 return "Concurrent marking (update refs)";
3118 } else if (proc_refs) {
3119 return "Concurrent marking (process weakrefs)";
3120 } else if (unload_cls) {
3121 return "Concurrent marking (unload classes)";
3122 } else {
3123 return "Concurrent marking";
3124 }
3125 }
3126
3127 const char* ShenandoahHeap::init_traversal_event_message() const {
3128 bool proc_refs = process_references();
3129 bool unload_cls = unload_classes();
3130
3131 if (proc_refs && unload_cls) {
3132 return "Pause Init Traversal (process weakrefs) (unload classes)";
3133 } else if (proc_refs) {
3134 return "Pause Init Traversal (process weakrefs)";
3135 } else if (unload_cls) {
3136 return "Pause Init Traversal (unload classes)";
3137 } else {
3138 return "Pause Init Traversal";
3139 }
3140 }
3141
3142 const char* ShenandoahHeap::final_traversal_event_message() const {
3143 bool proc_refs = process_references();
3144 bool unload_cls = unload_classes();
3145
3146 if (proc_refs && unload_cls) {
3147 return "Pause Final Traversal (process weakrefs) (unload classes)";
3148 } else if (proc_refs) {
3149 return "Pause Final Traversal (process weakrefs)";
3150 } else if (unload_cls) {
3151 return "Pause Final Traversal (unload classes)";
3152 } else {
3153 return "Pause Final Traversal";
3154 }
3155 }
3156
3157 const char* ShenandoahHeap::conc_traversal_event_message() const {
3158 bool proc_refs = process_references();
3159 bool unload_cls = unload_classes();
3160
3161 if (proc_refs && unload_cls) {
3162 return "Concurrent Traversal (process weakrefs) (unload classes)";
3163 } else if (proc_refs) {
3164 return "Concurrent Traversal (process weakrefs)";
3165 } else if (unload_cls) {
3166 return "Concurrent Traversal (unload classes)";
3167 } else {
3168 return "Concurrent Traversal";
3169 }
3170 }
3171
3172 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
3173 switch (point) {
3174 case _degenerated_unset:
3175 return "Pause Degenerated GC (<UNSET>)";
3176 case _degenerated_traversal:
3177 return "Pause Degenerated GC (Traversal)";
3178 case _degenerated_outside_cycle:
3179 return "Pause Degenerated GC (Outside of Cycle)";
3180 case _degenerated_mark:
3181 return "Pause Degenerated GC (Mark)";
3182 case _degenerated_evac:
3183 return "Pause Degenerated GC (Evacuation)";
3184 case _degenerated_updaterefs:
3185 return "Pause Degenerated GC (Update Refs)";
3186 default:
3187 ShouldNotReachHere();
3188 return "ERROR";
3189 }
3190 }
3191
3192 jushort* ShenandoahHeap::get_liveness_cache(uint worker_id) {
3193 #ifdef ASSERT
3194 assert(_liveness_cache != NULL, "sanity");
3195 assert(worker_id < _max_workers, "sanity");
3196 for (uint i = 0; i < num_regions(); i++) {
3197 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
3198 }
3199 #endif
3200 return _liveness_cache[worker_id];
3201 }
3202
3203 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
3204 assert(worker_id < _max_workers, "sanity");
3205 assert(_liveness_cache != NULL, "sanity");
3206 jushort* ld = _liveness_cache[worker_id];
3207 for (uint i = 0; i < num_regions(); i++) {
3208 ShenandoahHeapRegion* r = get_region(i);
3209 jushort live = ld[i];
3210 if (live > 0) {
3211 r->increase_live_data_gc_words(live);
3212 ld[i] = 0;
3213 }
3214 }
3215 }