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