1 /*
2 * Copyright (c) 2013, 2020, 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/oopStorageSet.hpp"
34 #include "gc/shared/plab.hpp"
35
36 #include "gc/shenandoah/shenandoahAllocTracker.hpp"
37 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
38 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
39 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
40 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
41 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
42 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
43 #include "gc/shenandoah/shenandoahControlThread.hpp"
44 #include "gc/shenandoah/shenandoahFreeSet.hpp"
45 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
46 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
47 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
48 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
49 #include "gc/shenandoah/shenandoahMarkCompact.hpp"
50 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
51 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
52 #include "gc/shenandoah/shenandoahMetrics.hpp"
53 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
54 #include "gc/shenandoah/shenandoahNormalMode.hpp"
55 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
56 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
57 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
58 #include "gc/shenandoah/shenandoahPassiveMode.hpp"
59 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
60 #include "gc/shenandoah/shenandoahStringDedup.hpp"
61 #include "gc/shenandoah/shenandoahTaskqueue.hpp"
62 #include "gc/shenandoah/shenandoahTraversalMode.hpp"
63 #include "gc/shenandoah/shenandoahUtils.hpp"
64 #include "gc/shenandoah/shenandoahVerifier.hpp"
65 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
66 #include "gc/shenandoah/shenandoahVMOperations.hpp"
67 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
68 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
69 #if INCLUDE_JFR
70 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
71 #endif
72
73 #include "memory/metaspace.hpp"
74 #include "oops/compressedOops.inline.hpp"
75 #include "runtime/atomic.hpp"
76 #include "runtime/globals.hpp"
77 #include "runtime/interfaceSupport.inline.hpp"
78 #include "runtime/orderAccess.hpp"
79 #include "runtime/safepointMechanism.hpp"
80 #include "runtime/vmThread.hpp"
81 #include "services/mallocTracker.hpp"
82
83 #ifdef ASSERT
84 template <class T>
85 void ShenandoahAssertToSpaceClosure::do_oop_work(T* p) {
86 T o = RawAccess<>::oop_load(p);
87 if (! CompressedOops::is_null(o)) {
88 oop obj = CompressedOops::decode_not_null(o);
89 shenandoah_assert_not_forwarded(p, obj);
90 }
91 }
92
93 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_work(p); }
94 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_work(p); }
95 #endif
96
97 class ShenandoahPretouchHeapTask : public AbstractGangTask {
98 private:
99 ShenandoahRegionIterator _regions;
100 const size_t _page_size;
101 public:
102 ShenandoahPretouchHeapTask(size_t page_size) :
103 AbstractGangTask("Shenandoah Pretouch Heap"),
104 _page_size(page_size) {}
105
106 virtual void work(uint worker_id) {
107 ShenandoahHeapRegion* r = _regions.next();
108 while (r != NULL) {
109 os::pretouch_memory(r->bottom(), r->end(), _page_size);
110 r = _regions.next();
111 }
112 }
113 };
114
115 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
116 private:
117 ShenandoahRegionIterator _regions;
118 char* _bitmap_base;
119 const size_t _bitmap_size;
120 const size_t _page_size;
121 public:
122 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
123 AbstractGangTask("Shenandoah Pretouch Bitmap"),
124 _bitmap_base(bitmap_base),
125 _bitmap_size(bitmap_size),
126 _page_size(page_size) {}
127
128 virtual void work(uint worker_id) {
129 ShenandoahHeapRegion* r = _regions.next();
130 while (r != NULL) {
131 size_t start = r->region_number() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
132 size_t end = (r->region_number() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
133 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
134
135 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
136
137 r = _regions.next();
138 }
139 }
140 };
141
142 jint ShenandoahHeap::initialize() {
143 initialize_heuristics();
144
145 //
146 // Figure out heap sizing
147 //
148
149 size_t init_byte_size = InitialHeapSize;
150 size_t min_byte_size = MinHeapSize;
151 size_t max_byte_size = MaxHeapSize;
152 size_t heap_alignment = HeapAlignment;
153
154 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
155
156 if (ShenandoahAlwaysPreTouch) {
157 // Enabled pre-touch means the entire heap is committed right away.
158 init_byte_size = max_byte_size;
159 }
160
161 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
162 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
163
164 _num_regions = ShenandoahHeapRegion::region_count();
165
166 size_t num_committed_regions = init_byte_size / reg_size_bytes;
167 num_committed_regions = MIN2(num_committed_regions, _num_regions);
168 assert(num_committed_regions <= _num_regions, "sanity");
169 _initial_size = num_committed_regions * reg_size_bytes;
170
171 size_t num_min_regions = min_byte_size / reg_size_bytes;
172 num_min_regions = MIN2(num_min_regions, _num_regions);
173 assert(num_min_regions <= _num_regions, "sanity");
174 _minimum_size = num_min_regions * reg_size_bytes;
175
176 _committed = _initial_size;
177
178 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
179 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
180
181 //
182 // Reserve and commit memory for heap
183 //
184
185 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
186 initialize_reserved_region(heap_rs);
187 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
188 _heap_region_special = heap_rs.special();
189
190 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
191 "Misaligned heap: " PTR_FORMAT, p2i(base()));
192
193 #if SHENANDOAH_OPTIMIZED_OBJTASK
194 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
195 // Fail if we ever attempt to address more than we can.
196 if ((uintptr_t)heap_rs.end() >= ObjArrayChunkedTask::max_addressable()) {
197 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
198 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
199 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
200 p2i(heap_rs.base()), p2i(heap_rs.end()), ObjArrayChunkedTask::max_addressable());
201 vm_exit_during_initialization("Fatal Error", buf);
202 }
203 #endif
204
205 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
206 if (!_heap_region_special) {
207 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
208 "Cannot commit heap memory");
209 }
210
211 //
212 // Reserve and commit memory for bitmap(s)
213 //
214
215 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
216 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
217
218 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
219
220 guarantee(bitmap_bytes_per_region != 0,
221 "Bitmap bytes per region should not be zero");
222 guarantee(is_power_of_2(bitmap_bytes_per_region),
223 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
224
225 if (bitmap_page_size > bitmap_bytes_per_region) {
226 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
227 _bitmap_bytes_per_slice = bitmap_page_size;
228 } else {
229 _bitmap_regions_per_slice = 1;
230 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
231 }
232
233 guarantee(_bitmap_regions_per_slice >= 1,
234 "Should have at least one region per slice: " SIZE_FORMAT,
235 _bitmap_regions_per_slice);
236
237 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
238 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
239 _bitmap_bytes_per_slice, bitmap_page_size);
240
241 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
242 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
243 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
244 _bitmap_region_special = bitmap.special();
245
246 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
247 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
248 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
249 if (!_bitmap_region_special) {
250 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
251 "Cannot commit bitmap memory");
252 }
253
254 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
255
256 if (ShenandoahVerify) {
257 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
258 if (!verify_bitmap.special()) {
259 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
260 "Cannot commit verification bitmap memory");
261 }
262 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
263 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
264 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
265 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
266 }
267
268 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
269 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
270 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
271 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
272 _aux_bitmap_region_special = aux_bitmap.special();
273 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
274
275 //
276 // Create regions and region sets
277 //
278
279 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
280 _free_set = new ShenandoahFreeSet(this, _num_regions);
281 _collection_set = new ShenandoahCollectionSet(this, sh_rs.base(), sh_rs.size());
282
283 {
284 ShenandoahHeapLocker locker(lock());
285
286 size_t size_words = ShenandoahHeapRegion::region_size_words();
287
288 for (size_t i = 0; i < _num_regions; i++) {
289 HeapWord* start = (HeapWord*)sh_rs.base() + size_words * i;
290 bool is_committed = i < num_committed_regions;
291 ShenandoahHeapRegion* r = new ShenandoahHeapRegion(this, start, size_words, i, is_committed);
292
293 _marking_context->initialize_top_at_mark_start(r);
294 _regions[i] = r;
295 assert(!collection_set()->is_in(i), "New region should not be in collection set");
296 }
297
298 // Initialize to complete
299 _marking_context->mark_complete();
300
301 _free_set->rebuild();
302 }
303
304 if (ShenandoahAlwaysPreTouch) {
305 assert(!AlwaysPreTouch, "Should have been overridden");
306
307 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
308 // before initialize() below zeroes it with initializing thread. For any given region,
309 // we touch the region and the corresponding bitmaps from the same thread.
310 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
311
312 size_t pretouch_heap_page_size = heap_page_size;
313 size_t pretouch_bitmap_page_size = bitmap_page_size;
314
315 #ifdef LINUX
316 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
317 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
318 // them into huge one. Therefore, we need to pretouch with smaller pages.
319 if (UseTransparentHugePages) {
320 pretouch_heap_page_size = (size_t)os::vm_page_size();
321 pretouch_bitmap_page_size = (size_t)os::vm_page_size();
322 }
323 #endif
324
325 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
326 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
327
328 log_info(gc, init)("Pretouch bitmap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
329 _num_regions, pretouch_bitmap_page_size);
330 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, pretouch_bitmap_page_size);
331 _workers->run_task(&bcl);
332
333 log_info(gc, init)("Pretouch heap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
334 _num_regions, pretouch_heap_page_size);
335 ShenandoahPretouchHeapTask hcl(pretouch_heap_page_size);
336 _workers->run_task(&hcl);
337 }
338
339 //
340 // Initialize the rest of GC subsystems
341 //
342
343 _liveness_cache = NEW_C_HEAP_ARRAY(jushort*, _max_workers, mtGC);
344 for (uint worker = 0; worker < _max_workers; worker++) {
345 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(jushort, _num_regions, mtGC);
346 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(jushort));
347 }
348
349 // There should probably be Shenandoah-specific options for these,
350 // just as there are G1-specific options.
351 {
352 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
353 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
354 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
355 }
356
357 _monitoring_support = new ShenandoahMonitoringSupport(this);
358 _phase_timings = new ShenandoahPhaseTimings();
359 ShenandoahStringDedup::initialize();
360 ShenandoahCodeRoots::initialize();
361
362 if (ShenandoahAllocationTrace) {
363 _alloc_tracker = new ShenandoahAllocTracker();
364 }
365
366 if (ShenandoahPacing) {
367 _pacer = new ShenandoahPacer(this);
368 _pacer->setup_for_idle();
369 } else {
370 _pacer = NULL;
371 }
372
373 _traversal_gc = strcmp(ShenandoahGCMode, "traversal") == 0 ?
374 new ShenandoahTraversalGC(this, _num_regions) :
375 NULL;
376
377 _control_thread = new ShenandoahControlThread();
378
379 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max",
380 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size),
381 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size),
382 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity())
383 );
384
385 log_info(gc, init)("Safepointing mechanism: %s",
386 SafepointMechanism::uses_thread_local_poll() ? "thread-local poll" :
387 (SafepointMechanism::uses_global_page_poll() ? "global-page poll" : "unknown"));
388
389 return JNI_OK;
390 }
391
392 void ShenandoahHeap::initialize_heuristics() {
393 if (ShenandoahGCMode != NULL) {
394 if (strcmp(ShenandoahGCMode, "traversal") == 0) {
395 _gc_mode = new ShenandoahTraversalMode();
396 } else if (strcmp(ShenandoahGCMode, "normal") == 0) {
397 _gc_mode = new ShenandoahNormalMode();
398 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
399 _gc_mode = new ShenandoahPassiveMode();
400 } else {
401 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
402 }
403 } else {
404 ShouldNotReachHere();
405 }
406 _gc_mode->initialize_flags();
407 _heuristics = _gc_mode->initialize_heuristics();
408
409 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
410 vm_exit_during_initialization(
411 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
412 _heuristics->name()));
413 }
414 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
415 vm_exit_during_initialization(
416 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
417 _heuristics->name()));
418 }
419 log_info(gc, init)("Shenandoah heuristics: %s",
420 _heuristics->name());
421 }
422
423 #ifdef _MSC_VER
424 #pragma warning( push )
425 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
426 #endif
427
428 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
429 CollectedHeap(),
430 _initial_size(0),
431 _used(0),
432 _committed(0),
433 _bytes_allocated_since_gc_start(0),
434 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
435 _workers(NULL),
436 _safepoint_workers(NULL),
437 _heap_region_special(false),
438 _num_regions(0),
439 _regions(NULL),
440 _update_refs_iterator(this),
441 _control_thread(NULL),
442 _shenandoah_policy(policy),
443 _heuristics(NULL),
444 _free_set(NULL),
445 _scm(new ShenandoahConcurrentMark()),
446 _traversal_gc(NULL),
447 _full_gc(new ShenandoahMarkCompact()),
448 _pacer(NULL),
449 _verifier(NULL),
450 _alloc_tracker(NULL),
451 _phase_timings(NULL),
452 _monitoring_support(NULL),
453 _memory_pool(NULL),
454 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
455 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
456 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
457 _soft_ref_policy(),
458 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
459 _ref_processor(NULL),
460 _marking_context(NULL),
461 _bitmap_size(0),
462 _bitmap_regions_per_slice(0),
463 _bitmap_bytes_per_slice(0),
464 _bitmap_region_special(false),
465 _aux_bitmap_region_special(false),
466 _liveness_cache(NULL),
467 _collection_set(NULL)
468 {
469 log_info(gc, init)("GC threads: " UINT32_FORMAT " parallel, " UINT32_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
470 log_info(gc, init)("Reference processing: %s", ParallelRefProcEnabled ? "parallel" : "serial");
471
472 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
473
474 _max_workers = MAX2(_max_workers, 1U);
475 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
476 /* are_GC_task_threads */ true,
477 /* are_ConcurrentGC_threads */ true);
478 if (_workers == NULL) {
479 vm_exit_during_initialization("Failed necessary allocation.");
480 } else {
481 _workers->initialize_workers();
482 }
483
484 if (ShenandoahParallelSafepointThreads > 1) {
485 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
486 ShenandoahParallelSafepointThreads,
487 /* are_GC_task_threads */ false,
488 /* are_ConcurrentGC_threads */ false);
489 _safepoint_workers->initialize_workers();
490 }
491 }
492
493 #ifdef _MSC_VER
494 #pragma warning( pop )
495 #endif
496
497 class ShenandoahResetBitmapTask : public AbstractGangTask {
498 private:
499 ShenandoahRegionIterator _regions;
500
501 public:
502 ShenandoahResetBitmapTask() :
503 AbstractGangTask("Parallel Reset Bitmap Task") {}
504
505 void work(uint worker_id) {
506 ShenandoahHeapRegion* region = _regions.next();
507 ShenandoahHeap* heap = ShenandoahHeap::heap();
508 ShenandoahMarkingContext* const ctx = heap->marking_context();
509 while (region != NULL) {
510 if (heap->is_bitmap_slice_committed(region)) {
511 ctx->clear_bitmap(region);
512 }
513 region = _regions.next();
514 }
515 }
516 };
517
518 void ShenandoahHeap::reset_mark_bitmap() {
519 assert_gc_workers(_workers->active_workers());
520 mark_incomplete_marking_context();
521
522 ShenandoahResetBitmapTask task;
523 _workers->run_task(&task);
524 }
525
526 void ShenandoahHeap::print_on(outputStream* st) const {
527 st->print_cr("Shenandoah Heap");
528 st->print_cr(" " SIZE_FORMAT "%s total, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
529 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
530 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
531 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
532 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
533 num_regions(),
534 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
535 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
536
537 st->print("Status: ");
538 if (has_forwarded_objects()) st->print("has forwarded objects, ");
539 if (is_concurrent_mark_in_progress()) st->print("marking, ");
540 if (is_evacuation_in_progress()) st->print("evacuating, ");
541 if (is_update_refs_in_progress()) st->print("updating refs, ");
542 if (is_concurrent_traversal_in_progress()) st->print("traversal, ");
543 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
544 if (is_full_gc_in_progress()) st->print("full gc, ");
545 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
546 if (is_concurrent_root_in_progress()) st->print("concurrent roots, ");
547
548 if (cancelled_gc()) {
549 st->print("cancelled");
550 } else {
551 st->print("not cancelled");
552 }
553 st->cr();
554
555 st->print_cr("Reserved region:");
556 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
557 p2i(reserved_region().start()),
558 p2i(reserved_region().end()));
559
560 ShenandoahCollectionSet* cset = collection_set();
561 st->print_cr("Collection set:");
562 if (cset != NULL) {
563 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
564 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
565 } else {
566 st->print_cr(" (NULL)");
567 }
568
569 st->cr();
570 MetaspaceUtils::print_on(st);
571
572 if (Verbose) {
573 print_heap_regions_on(st);
574 }
575 }
576
577 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
578 public:
579 void do_thread(Thread* thread) {
580 assert(thread != NULL, "Sanity");
581 assert(thread->is_Worker_thread(), "Only worker thread expected");
582 ShenandoahThreadLocalData::initialize_gclab(thread);
583 }
584 };
585
586 void ShenandoahHeap::post_initialize() {
587 CollectedHeap::post_initialize();
588 MutexLocker ml(Threads_lock);
589
590 ShenandoahInitWorkerGCLABClosure init_gclabs;
591 _workers->threads_do(&init_gclabs);
592
593 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
594 // Now, we will let WorkGang to initialize gclab when new worker is created.
595 _workers->set_initialize_gclab();
596
597 _scm->initialize(_max_workers);
598 _full_gc->initialize(_gc_timer);
599
600 ref_processing_init();
601
602 _heuristics->initialize();
603
604 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
605 }
606
607 size_t ShenandoahHeap::used() const {
608 return Atomic::load_acquire(&_used);
609 }
610
611 size_t ShenandoahHeap::committed() const {
612 OrderAccess::acquire();
613 return _committed;
614 }
615
616 void ShenandoahHeap::increase_committed(size_t bytes) {
617 assert_heaplock_or_safepoint();
618 _committed += bytes;
619 }
620
621 void ShenandoahHeap::decrease_committed(size_t bytes) {
622 assert_heaplock_or_safepoint();
623 _committed -= bytes;
624 }
625
626 void ShenandoahHeap::increase_used(size_t bytes) {
627 Atomic::add(&_used, bytes);
628 }
629
630 void ShenandoahHeap::set_used(size_t bytes) {
631 Atomic::release_store_fence(&_used, bytes);
632 }
633
634 void ShenandoahHeap::decrease_used(size_t bytes) {
635 assert(used() >= bytes, "never decrease heap size by more than we've left");
636 Atomic::sub(&_used, bytes);
637 }
638
639 void ShenandoahHeap::increase_allocated(size_t bytes) {
640 Atomic::add(&_bytes_allocated_since_gc_start, bytes);
641 }
642
643 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
644 size_t bytes = words * HeapWordSize;
645 if (!waste) {
646 increase_used(bytes);
647 }
648 increase_allocated(bytes);
649 if (ShenandoahPacing) {
650 control_thread()->pacing_notify_alloc(words);
651 if (waste) {
652 pacer()->claim_for_alloc(words, true);
653 }
654 }
655 }
656
657 size_t ShenandoahHeap::capacity() const {
658 return committed();
659 }
660
661 size_t ShenandoahHeap::max_capacity() const {
662 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
663 }
664
665 size_t ShenandoahHeap::min_capacity() const {
666 return _minimum_size;
667 }
668
669 size_t ShenandoahHeap::initial_capacity() const {
670 return _initial_size;
671 }
672
673 bool ShenandoahHeap::is_in(const void* p) const {
674 HeapWord* heap_base = (HeapWord*) base();
675 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
676 return p >= heap_base && p < last_region_end;
677 }
678
679 void ShenandoahHeap::op_uncommit(double shrink_before) {
680 assert (ShenandoahUncommit, "should be enabled");
681
682 // Application allocates from the beginning of the heap, and GC allocates at
683 // the end of it. It is more efficient to uncommit from the end, so that applications
684 // could enjoy the near committed regions. GC allocations are much less frequent,
685 // and therefore can accept the committing costs.
686
687 size_t count = 0;
688 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
689 ShenandoahHeapRegion* r = get_region(i - 1);
690 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
691 ShenandoahHeapLocker locker(lock());
692 if (r->is_empty_committed()) {
693 // Do not uncommit below minimal capacity
694 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
695 break;
696 }
697
698 r->make_uncommitted();
699 count++;
700 }
701 }
702 SpinPause(); // allow allocators to take the lock
703 }
704
705 if (count > 0) {
706 control_thread()->notify_heap_changed();
707 }
708 }
709
710 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
711 // New object should fit the GCLAB size
712 size_t min_size = MAX2(size, PLAB::min_size());
713
714 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
715 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
716 new_size = MIN2(new_size, PLAB::max_size());
717 new_size = MAX2(new_size, PLAB::min_size());
718
719 // Record new heuristic value even if we take any shortcut. This captures
720 // the case when moderately-sized objects always take a shortcut. At some point,
721 // heuristics should catch up with them.
722 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
723
724 if (new_size < size) {
725 // New size still does not fit the object. Fall back to shared allocation.
726 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
727 return NULL;
728 }
729
730 // Retire current GCLAB, and allocate a new one.
731 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
732 gclab->retire();
733
734 size_t actual_size = 0;
735 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
736 if (gclab_buf == NULL) {
737 return NULL;
738 }
739
740 assert (size <= actual_size, "allocation should fit");
741
742 if (ZeroTLAB) {
743 // ..and clear it.
744 Copy::zero_to_words(gclab_buf, actual_size);
745 } else {
746 // ...and zap just allocated object.
747 #ifdef ASSERT
748 // Skip mangling the space corresponding to the object header to
749 // ensure that the returned space is not considered parsable by
750 // any concurrent GC thread.
751 size_t hdr_size = oopDesc::header_size();
752 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
753 #endif // ASSERT
754 }
755 gclab->set_buf(gclab_buf, actual_size);
756 return gclab->allocate(size);
757 }
758
759 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
760 size_t requested_size,
761 size_t* actual_size) {
762 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
763 HeapWord* res = allocate_memory(req);
764 if (res != NULL) {
765 *actual_size = req.actual_size();
766 } else {
767 *actual_size = 0;
768 }
769 return res;
770 }
771
772 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
773 size_t word_size,
774 size_t* actual_size) {
775 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
776 HeapWord* res = allocate_memory(req);
777 if (res != NULL) {
778 *actual_size = req.actual_size();
779 } else {
780 *actual_size = 0;
781 }
782 return res;
783 }
784
785 ShenandoahHeap* ShenandoahHeap::heap() {
786 CollectedHeap* heap = Universe::heap();
787 assert(heap != NULL, "Unitialized access to ShenandoahHeap::heap()");
788 assert(heap->kind() == CollectedHeap::Shenandoah, "not a shenandoah heap");
789 return (ShenandoahHeap*) heap;
790 }
791
792 ShenandoahHeap* ShenandoahHeap::heap_no_check() {
793 CollectedHeap* heap = Universe::heap();
794 return (ShenandoahHeap*) heap;
795 }
796
797 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
798 ShenandoahAllocTrace trace_alloc(req.size(), req.type());
799
800 intptr_t pacer_epoch = 0;
801 bool in_new_region = false;
802 HeapWord* result = NULL;
803
804 if (req.is_mutator_alloc()) {
805 if (ShenandoahPacing) {
806 pacer()->pace_for_alloc(req.size());
807 pacer_epoch = pacer()->epoch();
808 }
809
810 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
811 result = allocate_memory_under_lock(req, in_new_region);
812 }
813
814 // Allocation failed, block until control thread reacted, then retry allocation.
815 //
816 // It might happen that one of the threads requesting allocation would unblock
817 // way later after GC happened, only to fail the second allocation, because
818 // other threads have already depleted the free storage. In this case, a better
819 // strategy is to try again, as long as GC makes progress.
820 //
821 // Then, we need to make sure the allocation was retried after at least one
822 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
823
824 size_t tries = 0;
825
826 while (result == NULL && _progress_last_gc.is_set()) {
827 tries++;
828 control_thread()->handle_alloc_failure(req.size());
829 result = allocate_memory_under_lock(req, in_new_region);
830 }
831
832 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
833 tries++;
834 control_thread()->handle_alloc_failure(req.size());
835 result = allocate_memory_under_lock(req, in_new_region);
836 }
837
838 } else {
839 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
840 result = allocate_memory_under_lock(req, in_new_region);
841 // Do not call handle_alloc_failure() here, because we cannot block.
842 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
843 }
844
845 if (in_new_region) {
846 control_thread()->notify_heap_changed();
847 }
848
849 if (result != NULL) {
850 size_t requested = req.size();
851 size_t actual = req.actual_size();
852
853 assert (req.is_lab_alloc() || (requested == actual),
854 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
855 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
856
857 if (req.is_mutator_alloc()) {
858 notify_mutator_alloc_words(actual, false);
859
860 // If we requested more than we were granted, give the rest back to pacer.
861 // This only matters if we are in the same pacing epoch: do not try to unpace
862 // over the budget for the other phase.
863 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
864 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
865 }
866 } else {
867 increase_used(actual*HeapWordSize);
868 }
869 }
870
871 return result;
872 }
873
874 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
875 ShenandoahHeapLocker locker(lock());
876 return _free_set->allocate(req, in_new_region);
877 }
878
879 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
880 bool* gc_overhead_limit_was_exceeded) {
881 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
882 return allocate_memory(req);
883 }
884
885 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
886 size_t size,
887 Metaspace::MetadataType mdtype) {
888 MetaWord* result;
889
890 // Inform metaspace OOM to GC heuristics if class unloading is possible.
891 if (heuristics()->can_unload_classes()) {
892 ShenandoahHeuristics* h = heuristics();
893 h->record_metaspace_oom();
894 }
895
896 // Expand and retry allocation
897 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
898 if (result != NULL) {
899 return result;
900 }
901
902 // Start full GC
903 collect(GCCause::_metadata_GC_clear_soft_refs);
904
905 // Retry allocation
906 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
907 if (result != NULL) {
908 return result;
909 }
910
911 // Expand and retry allocation
912 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
913 if (result != NULL) {
914 return result;
915 }
916
917 // Out of memory
918 return NULL;
919 }
920
921 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
922 private:
923 ShenandoahHeap* const _heap;
924 Thread* const _thread;
925 public:
926 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
927 _heap(heap), _thread(Thread::current()) {}
928
929 void do_object(oop p) {
930 shenandoah_assert_marked(NULL, p);
931 if (!p->is_forwarded()) {
932 _heap->evacuate_object(p, _thread);
933 }
934 }
935 };
936
937 class ShenandoahEvacuationTask : public AbstractGangTask {
938 private:
939 ShenandoahHeap* const _sh;
940 ShenandoahCollectionSet* const _cs;
941 bool _concurrent;
942 public:
943 ShenandoahEvacuationTask(ShenandoahHeap* sh,
944 ShenandoahCollectionSet* cs,
945 bool concurrent) :
946 AbstractGangTask("Parallel Evacuation Task"),
947 _sh(sh),
948 _cs(cs),
949 _concurrent(concurrent)
950 {}
951
952 void work(uint worker_id) {
953 if (_concurrent) {
954 ShenandoahConcurrentWorkerSession worker_session(worker_id);
955 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
956 ShenandoahEvacOOMScope oom_evac_scope;
957 do_work();
958 } else {
959 ShenandoahParallelWorkerSession worker_session(worker_id);
960 ShenandoahEvacOOMScope oom_evac_scope;
961 do_work();
962 }
963 }
964
965 private:
966 void do_work() {
967 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
968 ShenandoahHeapRegion* r;
969 while ((r =_cs->claim_next()) != NULL) {
970 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->region_number());
971 _sh->marked_object_iterate(r, &cl);
972
973 if (ShenandoahPacing) {
974 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
975 }
976
977 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
978 break;
979 }
980 }
981 }
982 };
983
984 void ShenandoahHeap::trash_cset_regions() {
985 ShenandoahHeapLocker locker(lock());
986
987 ShenandoahCollectionSet* set = collection_set();
988 ShenandoahHeapRegion* r;
989 set->clear_current_index();
990 while ((r = set->next()) != NULL) {
991 r->make_trash();
992 }
993 collection_set()->clear();
994 }
995
996 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
997 st->print_cr("Heap Regions:");
998 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
999 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
1000 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start (previous, next)");
1001 st->print_cr("SN=alloc sequence numbers (first mutator, last mutator, first gc, last gc)");
1002
1003 for (size_t i = 0; i < num_regions(); i++) {
1004 get_region(i)->print_on(st);
1005 }
1006 }
1007
1008 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1009 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1010
1011 oop humongous_obj = oop(start->bottom());
1012 size_t size = humongous_obj->size();
1013 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1014 size_t index = start->region_number() + required_regions - 1;
1015
1016 assert(!start->has_live(), "liveness must be zero");
1017
1018 for(size_t i = 0; i < required_regions; i++) {
1019 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1020 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1021 ShenandoahHeapRegion* region = get_region(index --);
1022
1023 assert(region->is_humongous(), "expect correct humongous start or continuation");
1024 assert(!region->is_cset(), "Humongous region should not be in collection set");
1025
1026 region->make_trash_immediate();
1027 }
1028 }
1029
1030 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1031 public:
1032 void do_thread(Thread* thread) {
1033 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1034 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1035 gclab->retire();
1036 }
1037 };
1038
1039 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
1040 if (UseTLAB) {
1041 CollectedHeap::ensure_parsability(retire_tlabs);
1042 }
1043 ShenandoahRetireGCLABClosure cl;
1044 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1045 cl.do_thread(t);
1046 }
1047 workers()->threads_do(&cl);
1048 }
1049
1050 void ShenandoahHeap::resize_tlabs() {
1051 CollectedHeap::resize_all_tlabs();
1052 }
1053
1054 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1055 private:
1056 ShenandoahRootEvacuator* _rp;
1057
1058 public:
1059 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1060 AbstractGangTask("Shenandoah evacuate and update roots"),
1061 _rp(rp) {}
1062
1063 void work(uint worker_id) {
1064 ShenandoahParallelWorkerSession worker_session(worker_id);
1065 ShenandoahEvacOOMScope oom_evac_scope;
1066 ShenandoahEvacuateUpdateRootsClosure cl;
1067 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1068 _rp->roots_do(worker_id, &cl);
1069 }
1070 };
1071
1072 void ShenandoahHeap::evacuate_and_update_roots() {
1073 #if COMPILER2_OR_JVMCI
1074 DerivedPointerTable::clear();
1075 #endif
1076 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1077 {
1078 // Include concurrent roots if current cycle can not process those roots concurrently
1079 ShenandoahRootEvacuator rp(workers()->active_workers(),
1080 ShenandoahPhaseTimings::init_evac,
1081 !ShenandoahConcurrentRoots::should_do_concurrent_roots(),
1082 !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
1083 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1084 workers()->run_task(&roots_task);
1085 }
1086
1087 #if COMPILER2_OR_JVMCI
1088 DerivedPointerTable::update_pointers();
1089 #endif
1090 }
1091
1092 // Returns size in bytes
1093 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1094 if (ShenandoahElasticTLAB) {
1095 // With Elastic TLABs, return the max allowed size, and let the allocation path
1096 // figure out the safe size for current allocation.
1097 return ShenandoahHeapRegion::max_tlab_size_bytes();
1098 } else {
1099 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1100 }
1101 }
1102
1103 size_t ShenandoahHeap::max_tlab_size() const {
1104 // Returns size in words
1105 return ShenandoahHeapRegion::max_tlab_size_words();
1106 }
1107
1108 class ShenandoahRetireAndResetGCLABClosure : public ThreadClosure {
1109 public:
1110 void do_thread(Thread* thread) {
1111 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1112 gclab->retire();
1113 if (ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1114 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1115 }
1116 }
1117 };
1118
1119 void ShenandoahHeap::retire_and_reset_gclabs() {
1120 ShenandoahRetireAndResetGCLABClosure cl;
1121 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1122 cl.do_thread(t);
1123 }
1124 workers()->threads_do(&cl);
1125 }
1126
1127 void ShenandoahHeap::collect(GCCause::Cause cause) {
1128 control_thread()->request_gc(cause);
1129 }
1130
1131 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1132 //assert(false, "Shouldn't need to do full collections");
1133 }
1134
1135 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1136 Space* sp = heap_region_containing(addr);
1137 if (sp != NULL) {
1138 return sp->block_start(addr);
1139 }
1140 return NULL;
1141 }
1142
1143 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1144 Space* sp = heap_region_containing(addr);
1145 return sp->block_is_obj(addr);
1146 }
1147
1148 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1149 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1150 }
1151
1152 jlong ShenandoahHeap::millis_since_last_gc() {
1153 double v = heuristics()->time_since_last_gc() * 1000;
1154 assert(0 <= v && v <= max_jlong, "value should fit: %f", v);
1155 return (jlong)v;
1156 }
1157
1158 void ShenandoahHeap::prepare_for_verify() {
1159 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1160 make_parsable(false);
1161 }
1162 }
1163
1164 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1165 workers()->print_worker_threads_on(st);
1166 if (ShenandoahStringDedup::is_enabled()) {
1167 ShenandoahStringDedup::print_worker_threads_on(st);
1168 }
1169 }
1170
1171 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1172 workers()->threads_do(tcl);
1173 if (_safepoint_workers != NULL) {
1174 _safepoint_workers->threads_do(tcl);
1175 }
1176 if (ShenandoahStringDedup::is_enabled()) {
1177 ShenandoahStringDedup::threads_do(tcl);
1178 }
1179 }
1180
1181 void ShenandoahHeap::print_tracing_info() const {
1182 LogTarget(Info, gc, stats) lt;
1183 if (lt.is_enabled()) {
1184 ResourceMark rm;
1185 LogStream ls(lt);
1186
1187 phase_timings()->print_on(&ls);
1188
1189 ls.cr();
1190 ls.cr();
1191
1192 shenandoah_policy()->print_gc_stats(&ls);
1193
1194 ls.cr();
1195 ls.cr();
1196
1197 if (ShenandoahPacing) {
1198 pacer()->print_on(&ls);
1199 }
1200
1201 ls.cr();
1202 ls.cr();
1203
1204 if (ShenandoahAllocationTrace) {
1205 assert(alloc_tracker() != NULL, "Must be");
1206 alloc_tracker()->print_on(&ls);
1207 } else {
1208 ls.print_cr(" Allocation tracing is disabled, use -XX:+ShenandoahAllocationTrace to enable.");
1209 }
1210 }
1211 }
1212
1213 void ShenandoahHeap::verify(VerifyOption vo) {
1214 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1215 if (ShenandoahVerify) {
1216 verifier()->verify_generic(vo);
1217 } else {
1218 // TODO: Consider allocating verification bitmaps on demand,
1219 // and turn this on unconditionally.
1220 }
1221 }
1222 }
1223 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1224 return _free_set->capacity();
1225 }
1226
1227 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1228 private:
1229 MarkBitMap* _bitmap;
1230 Stack<oop,mtGC>* _oop_stack;
1231
1232 template <class T>
1233 void do_oop_work(T* p) {
1234 T o = RawAccess<>::oop_load(p);
1235 if (!CompressedOops::is_null(o)) {
1236 oop obj = CompressedOops::decode_not_null(o);
1237 oop fwd = (oop) ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
1238 if (fwd == NULL) {
1239 // There is an odd interaction with VM_HeapWalkOperation, see jvmtiTagMap.cpp.
1240 //
1241 // That operation walks the reachable objects on its own, storing the marking
1242 // wavefront in the object marks. When it is done, it calls the CollectedHeap
1243 // to iterate over all objects to clean up the mess. When it reaches here,
1244 // the Shenandoah fwdptr resolution code encounters the marked objects with
1245 // NULL forwardee. Trying to act on that would crash the VM. Or fail the
1246 // asserts, should we go for resolve_forwarded_pointer(obj).
1247 //
1248 // Therefore, we have to dodge it by doing the raw access to forwardee, and
1249 // assuming the object had no forwardee, if that thing is NULL.
1250 } else {
1251 obj = fwd;
1252 }
1253 assert(oopDesc::is_oop(obj), "must be a valid oop");
1254 if (!_bitmap->is_marked((HeapWord*) obj)) {
1255 _bitmap->mark((HeapWord*) obj);
1256 _oop_stack->push(obj);
1257 }
1258 }
1259 }
1260 public:
1261 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1262 _bitmap(bitmap), _oop_stack(oop_stack) {}
1263 void do_oop(oop* p) { do_oop_work(p); }
1264 void do_oop(narrowOop* p) { do_oop_work(p); }
1265 };
1266
1267 /*
1268 * This is public API, used in preparation of object_iterate().
1269 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1270 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1271 * control, we call SH::make_tlabs_parsable().
1272 */
1273 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1274 // No-op.
1275 }
1276
1277 /*
1278 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1279 *
1280 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1281 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1282 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1283 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1284 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1285 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1286 * wiped the bitmap in preparation for next marking).
1287 *
1288 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1289 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1290 * is allowed to report dead objects, but is not required to do so.
1291 */
1292 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1293 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1294 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1295 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1296 return;
1297 }
1298
1299 // Reset bitmap
1300 _aux_bit_map.clear();
1301
1302 Stack<oop,mtGC> oop_stack;
1303
1304 // First, we process GC roots according to current GC cycle. This populates the work stack with initial objects.
1305 ShenandoahHeapIterationRootScanner rp;
1306 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1307
1308 // If we are unloading classes right now, we should not touch weak roots,
1309 // on the off-chance we would evacuate them and make them live accidentally.
1310 // In other cases, we have to scan all roots.
1311 if (is_evacuation_in_progress() && unload_classes()) {
1312 rp.strong_roots_do(&oops);
1313 } else {
1314 rp.roots_do(&oops);
1315 }
1316
1317 // Work through the oop stack to traverse heap.
1318 while (! oop_stack.is_empty()) {
1319 oop obj = oop_stack.pop();
1320 assert(oopDesc::is_oop(obj), "must be a valid oop");
1321 cl->do_object(obj);
1322 obj->oop_iterate(&oops);
1323 }
1324
1325 assert(oop_stack.is_empty(), "should be empty");
1326
1327 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1328 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1329 }
1330 }
1331
1332 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1333 void ShenandoahHeap::keep_alive(oop obj) {
1334 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1335 }
1336
1337 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1338 for (size_t i = 0; i < num_regions(); i++) {
1339 ShenandoahHeapRegion* current = get_region(i);
1340 blk->heap_region_do(current);
1341 }
1342 }
1343
1344 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1345 private:
1346 ShenandoahHeap* const _heap;
1347 ShenandoahHeapRegionClosure* const _blk;
1348
1349 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));
1350 volatile size_t _index;
1351 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
1352
1353 public:
1354 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1355 AbstractGangTask("Parallel Region Task"),
1356 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1357
1358 void work(uint worker_id) {
1359 size_t stride = ShenandoahParallelRegionStride;
1360
1361 size_t max = _heap->num_regions();
1362 while (_index < max) {
1363 size_t cur = Atomic::add(&_index, stride) - stride;
1364 size_t start = cur;
1365 size_t end = MIN2(cur + stride, max);
1366 if (start >= max) break;
1367
1368 for (size_t i = cur; i < end; i++) {
1369 ShenandoahHeapRegion* current = _heap->get_region(i);
1370 _blk->heap_region_do(current);
1371 }
1372 }
1373 }
1374 };
1375
1376 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1377 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1378 if (num_regions() > ShenandoahParallelRegionStride) {
1379 ShenandoahParallelHeapRegionTask task(blk);
1380 workers()->run_task(&task);
1381 } else {
1382 heap_region_iterate(blk);
1383 }
1384 }
1385
1386 class ShenandoahClearLivenessClosure : public ShenandoahHeapRegionClosure {
1387 private:
1388 ShenandoahMarkingContext* const _ctx;
1389 public:
1390 ShenandoahClearLivenessClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1391
1392 void heap_region_do(ShenandoahHeapRegion* r) {
1393 if (r->is_active()) {
1394 r->clear_live_data();
1395 _ctx->capture_top_at_mark_start(r);
1396 } else {
1397 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1398 assert(_ctx->top_at_mark_start(r) == r->top(),
1399 "Region " SIZE_FORMAT " should already have correct TAMS", r->region_number());
1400 }
1401 }
1402
1403 bool is_thread_safe() { return true; }
1404 };
1405
1406 void ShenandoahHeap::op_init_mark() {
1407 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1408 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1409
1410 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1411 assert(!marking_context()->is_complete(), "should not be complete");
1412
1413 if (ShenandoahVerify) {
1414 verifier()->verify_before_concmark();
1415 }
1416
1417 if (VerifyBeforeGC) {
1418 Universe::verify();
1419 }
1420
1421 set_concurrent_mark_in_progress(true);
1422 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1423 {
1424 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1425 make_parsable(true);
1426 }
1427
1428 {
1429 ShenandoahGCPhase phase(ShenandoahPhaseTimings::clear_liveness);
1430 ShenandoahClearLivenessClosure clc;
1431 parallel_heap_region_iterate(&clc);
1432 }
1433
1434 // Make above changes visible to worker threads
1435 OrderAccess::fence();
1436
1437 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1438
1439 if (UseTLAB) {
1440 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1441 resize_tlabs();
1442 }
1443
1444 if (ShenandoahPacing) {
1445 pacer()->setup_for_mark();
1446 }
1447 }
1448
1449 void ShenandoahHeap::op_mark() {
1450 concurrent_mark()->mark_from_roots();
1451 }
1452
1453 class ShenandoahCompleteLivenessClosure : public ShenandoahHeapRegionClosure {
1454 private:
1455 ShenandoahMarkingContext* const _ctx;
1456 public:
1457 ShenandoahCompleteLivenessClosure() : _ctx(ShenandoahHeap::heap()->complete_marking_context()) {}
1458
1459 void heap_region_do(ShenandoahHeapRegion* r) {
1460 if (r->is_active()) {
1461 HeapWord *tams = _ctx->top_at_mark_start(r);
1462 HeapWord *top = r->top();
1463 if (top > tams) {
1464 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1465 }
1466 } else {
1467 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->region_number());
1468 assert(_ctx->top_at_mark_start(r) == r->top(),
1469 "Region " SIZE_FORMAT " should have correct TAMS", r->region_number());
1470 }
1471 }
1472
1473 bool is_thread_safe() { return true; }
1474 };
1475
1476 void ShenandoahHeap::op_final_mark() {
1477 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1478
1479 // It is critical that we
1480 // evacuate roots right after finishing marking, so that we don't
1481 // get unmarked objects in the roots.
1482
1483 if (!cancelled_gc()) {
1484 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1485
1486 // Marking is completed, deactivate SATB barrier
1487 set_concurrent_mark_in_progress(false);
1488 mark_complete_marking_context();
1489
1490 parallel_cleaning(false /* full gc*/);
1491
1492 if (has_forwarded_objects()) {
1493 // Degen may be caused by failed evacuation of roots
1494 if (is_degenerated_gc_in_progress()) {
1495 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
1496 } else {
1497 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::update_roots);
1498 }
1499 set_has_forwarded_objects(false);
1500 }
1501
1502 if (ShenandoahVerify) {
1503 verifier()->verify_roots_no_forwarded();
1504 }
1505 // All allocations past TAMS are implicitly live, adjust the region data.
1506 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1507 {
1508 ShenandoahGCPhase phase(ShenandoahPhaseTimings::complete_liveness);
1509 ShenandoahCompleteLivenessClosure cl;
1510 parallel_heap_region_iterate(&cl);
1511 }
1512
1513 // Force the threads to reacquire their TLABs outside the collection set.
1514 {
1515 ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs);
1516 make_parsable(true);
1517 }
1518
1519 // We are about to select the collection set, make sure it knows about
1520 // current pinning status. Also, this allows trashing more regions that
1521 // now have their pinning status dropped.
1522 {
1523 ShenandoahGCPhase phase(ShenandoahPhaseTimings::sync_pinned);
1524 sync_pinned_region_status();
1525 }
1526
1527 // Trash the collection set left over from previous cycle, if any.
1528 {
1529 ShenandoahGCPhase phase(ShenandoahPhaseTimings::trash_cset);
1530 trash_cset_regions();
1531 }
1532
1533 {
1534 ShenandoahGCPhase phase(ShenandoahPhaseTimings::prepare_evac);
1535
1536 ShenandoahHeapLocker locker(lock());
1537 _collection_set->clear();
1538 _free_set->clear();
1539
1540 heuristics()->choose_collection_set(_collection_set);
1541
1542 _free_set->rebuild();
1543 }
1544
1545 if (!is_degenerated_gc_in_progress()) {
1546 prepare_concurrent_roots();
1547 prepare_concurrent_unloading();
1548 }
1549
1550 // If collection set has candidates, start evacuation.
1551 // Otherwise, bypass the rest of the cycle.
1552 if (!collection_set()->is_empty()) {
1553 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1554
1555 if (ShenandoahVerify) {
1556 verifier()->verify_before_evacuation();
1557 }
1558
1559 set_evacuation_in_progress(true);
1560 // From here on, we need to update references.
1561 set_has_forwarded_objects(true);
1562
1563 if (!is_degenerated_gc_in_progress()) {
1564 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1565 ShenandoahCodeRoots::arm_nmethods();
1566 }
1567 evacuate_and_update_roots();
1568 }
1569
1570 if (ShenandoahPacing) {
1571 pacer()->setup_for_evac();
1572 }
1573
1574 if (ShenandoahVerify) {
1575 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::None;
1576 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1577 types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots);
1578 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots);
1579 }
1580
1581 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1582 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CodeRoots);
1583 }
1584 verifier()->verify_roots_no_forwarded_except(types);
1585 verifier()->verify_during_evacuation();
1586 }
1587 } else {
1588 if (ShenandoahVerify) {
1589 verifier()->verify_after_concmark();
1590 }
1591
1592 if (VerifyAfterGC) {
1593 Universe::verify();
1594 }
1595 }
1596
1597 } else {
1598 // If this cycle was updating references, we need to keep the has_forwarded_objects
1599 // flag on, for subsequent phases to deal with it.
1600 concurrent_mark()->cancel();
1601 set_concurrent_mark_in_progress(false);
1602
1603 if (process_references()) {
1604 // Abandon reference processing right away: pre-cleaning must have failed.
1605 ReferenceProcessor *rp = ref_processor();
1606 rp->disable_discovery();
1607 rp->abandon_partial_discovery();
1608 rp->verify_no_references_recorded();
1609 }
1610 }
1611 }
1612
1613 void ShenandoahHeap::op_final_evac() {
1614 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1615
1616 set_evacuation_in_progress(false);
1617
1618 {
1619 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_retire_gclabs);
1620 retire_and_reset_gclabs();
1621 }
1622
1623 if (ShenandoahVerify) {
1624 verifier()->verify_after_evacuation();
1625 }
1626
1627 if (VerifyAfterGC) {
1628 Universe::verify();
1629 }
1630 }
1631
1632 void ShenandoahHeap::op_conc_evac() {
1633 ShenandoahEvacuationTask task(this, _collection_set, true);
1634 workers()->run_task(&task);
1635 }
1636
1637 void ShenandoahHeap::op_stw_evac() {
1638 ShenandoahEvacuationTask task(this, _collection_set, false);
1639 workers()->run_task(&task);
1640 }
1641
1642 void ShenandoahHeap::op_updaterefs() {
1643 update_heap_references(true);
1644 }
1645
1646 void ShenandoahHeap::op_cleanup() {
1647 free_set()->recycle_trash();
1648 }
1649
1650 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask {
1651 private:
1652 ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
1653 ShenandoahWeakRoots<true /*concurrent*/> _weak_roots;
1654 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots;
1655 bool _include_weak_roots;
1656
1657 public:
1658 ShenandoahConcurrentRootsEvacUpdateTask(bool include_weak_roots) :
1659 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Roots Task"),
1660 _include_weak_roots(include_weak_roots) {
1661 }
1662
1663 void work(uint worker_id) {
1664 ShenandoahEvacOOMScope oom;
1665 {
1666 // vm_roots and weak_roots are OopStorage backed roots, concurrent iteration
1667 // may race against OopStorage::release() calls.
1668 ShenandoahEvacUpdateOopStorageRootsClosure cl;
1669 _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1670
1671 if (_include_weak_roots) {
1672 _weak_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
1673 }
1674 }
1675
1676 {
1677 ShenandoahEvacuateUpdateRootsClosure cl;
1678 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1679 _cld_roots.cld_do(&clds);
1680 }
1681 }
1682 };
1683
1684 class ShenandoahEvacUpdateCleanupOopStorageRootsClosure : public BasicOopIterateClosure {
1685 private:
1686 ShenandoahHeap* const _heap;
1687 ShenandoahMarkingContext* const _mark_context;
1688 bool _evac_in_progress;
1689 Thread* const _thread;
1690 size_t _dead_counter;
1691
1692 public:
1693 ShenandoahEvacUpdateCleanupOopStorageRootsClosure();
1694 void do_oop(oop* p);
1695 void do_oop(narrowOop* p);
1696
1697 size_t dead_counter() const;
1698 void reset_dead_counter();
1699 };
1700
1701 ShenandoahEvacUpdateCleanupOopStorageRootsClosure::ShenandoahEvacUpdateCleanupOopStorageRootsClosure() :
1702 _heap(ShenandoahHeap::heap()),
1703 _mark_context(ShenandoahHeap::heap()->marking_context()),
1704 _evac_in_progress(ShenandoahHeap::heap()->is_evacuation_in_progress()),
1705 _thread(Thread::current()),
1706 _dead_counter(0) {
1707 }
1708
1709 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(oop* p) {
1710 const oop obj = RawAccess<>::oop_load(p);
1711 if (!CompressedOops::is_null(obj)) {
1712 if (!_mark_context->is_marked(obj)) {
1713 shenandoah_assert_correct(p, obj);
1714 oop old = Atomic::cmpxchg(p, obj, oop(NULL));
1715 if (obj == old) {
1716 _dead_counter ++;
1717 }
1718 assert(*p == NULL, "Must be");
1719 } else if (_evac_in_progress && _heap->in_collection_set(obj)) {
1720 oop resolved = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1721 if (resolved == obj) {
1722 resolved = _heap->evacuate_object(obj, _thread);
1723 }
1724 Atomic::cmpxchg(p, obj, resolved);
1725 assert(_heap->cancelled_gc() ||
1726 _mark_context->is_marked(resolved) && !_heap->in_collection_set(resolved),
1727 "Sanity");
1728 }
1729 }
1730 }
1731
1732 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(narrowOop* p) {
1733 ShouldNotReachHere();
1734 }
1735
1736 size_t ShenandoahEvacUpdateCleanupOopStorageRootsClosure::dead_counter() const {
1737 return _dead_counter;
1738 }
1739
1740 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::reset_dead_counter() {
1741 _dead_counter = 0;
1742 }
1743
1744 // This task not only evacuates/updates marked weak roots, but also "NULL"
1745 // dead weak roots.
1746 class ShenandoahConcurrentWeakRootsEvacUpdateTask : public AbstractGangTask {
1747 private:
1748 ShenandoahWeakRoot<true /*concurrent*/> _jni_roots;
1749 ShenandoahWeakRoot<true /*concurrent*/> _string_table_roots;
1750 ShenandoahWeakRoot<true /*concurrent*/> _resolved_method_table_roots;
1751 ShenandoahWeakRoot<true /*concurrent*/> _vm_roots;
1752
1753 public:
1754 ShenandoahConcurrentWeakRootsEvacUpdateTask() :
1755 AbstractGangTask("Shenandoah Concurrent Weak Root Task"),
1756 _jni_roots(OopStorageSet::jni_weak(), ShenandoahPhaseTimings::JNIWeakRoots),
1757 _string_table_roots(OopStorageSet::string_table_weak(), ShenandoahPhaseTimings::StringTableRoots),
1758 _resolved_method_table_roots(OopStorageSet::resolved_method_table_weak(), ShenandoahPhaseTimings::ResolvedMethodTableRoots),
1759 _vm_roots(OopStorageSet::vm_weak(), ShenandoahPhaseTimings::VMWeakRoots) {
1760 StringTable::reset_dead_counter();
1761 ResolvedMethodTable::reset_dead_counter();
1762 }
1763
1764 ~ShenandoahConcurrentWeakRootsEvacUpdateTask() {
1765 StringTable::finish_dead_counter();
1766 ResolvedMethodTable::finish_dead_counter();
1767 }
1768
1769 void work(uint worker_id) {
1770 ShenandoahEvacOOMScope oom;
1771 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
1772 // may race against OopStorage::release() calls.
1773 ShenandoahEvacUpdateCleanupOopStorageRootsClosure cl;
1774 _jni_roots.oops_do(&cl, worker_id);
1775 _vm_roots.oops_do(&cl, worker_id);
1776
1777 cl.reset_dead_counter();
1778 _string_table_roots.oops_do(&cl, worker_id);
1779 StringTable::inc_dead_counter(cl.dead_counter());
1780
1781 cl.reset_dead_counter();
1782 _resolved_method_table_roots.oops_do(&cl, worker_id);
1783 ResolvedMethodTable::inc_dead_counter(cl.dead_counter());
1784 }
1785 };
1786
1787 void ShenandoahHeap::op_roots() {
1788 if (is_concurrent_root_in_progress()) {
1789 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1790 // Concurrent weak root processing
1791 ShenandoahConcurrentWeakRootsEvacUpdateTask task;
1792 workers()->run_task(&task);
1793
1794 _unloader.unload();
1795 }
1796
1797 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1798 ShenandoahConcurrentRootsEvacUpdateTask task(!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
1799 workers()->run_task(&task);
1800 }
1801 }
1802
1803 set_concurrent_root_in_progress(false);
1804 }
1805
1806 void ShenandoahHeap::op_reset() {
1807 reset_mark_bitmap();
1808 }
1809
1810 void ShenandoahHeap::op_preclean() {
1811 concurrent_mark()->preclean_weak_refs();
1812 }
1813
1814 void ShenandoahHeap::op_init_traversal() {
1815 traversal_gc()->init_traversal_collection();
1816 }
1817
1818 void ShenandoahHeap::op_traversal() {
1819 traversal_gc()->concurrent_traversal_collection();
1820 }
1821
1822 void ShenandoahHeap::op_final_traversal() {
1823 traversal_gc()->final_traversal_collection();
1824 }
1825
1826 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1827 ShenandoahMetricsSnapshot metrics;
1828 metrics.snap_before();
1829
1830 full_gc()->do_it(cause);
1831 if (UseTLAB) {
1832 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs);
1833 resize_all_tlabs();
1834 }
1835
1836 metrics.snap_after();
1837
1838 if (metrics.is_good_progress()) {
1839 _progress_last_gc.set();
1840 } else {
1841 // Nothing to do. Tell the allocation path that we have failed to make
1842 // progress, and it can finally fail.
1843 _progress_last_gc.unset();
1844 }
1845 }
1846
1847 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1848 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1849 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1850 // some phase, we have to upgrade the Degenerate GC to Full GC.
1851
1852 clear_cancelled_gc();
1853
1854 ShenandoahMetricsSnapshot metrics;
1855 metrics.snap_before();
1856
1857 switch (point) {
1858 case _degenerated_traversal:
1859 {
1860 // Drop the collection set. Note: this leaves some already forwarded objects
1861 // behind, which may be problematic, see comments for ShenandoahEvacAssist
1862 // workarounds in ShenandoahTraversalHeuristics.
1863
1864 ShenandoahHeapLocker locker(lock());
1865 collection_set()->clear_current_index();
1866 for (size_t i = 0; i < collection_set()->count(); i++) {
1867 ShenandoahHeapRegion* r = collection_set()->next();
1868 r->make_regular_bypass();
1869 }
1870 collection_set()->clear();
1871 }
1872 op_final_traversal();
1873 op_cleanup();
1874 return;
1875
1876 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1877 // but enters it at different points, depending on which concurrent phase had
1878 // degenerated.
1879
1880 case _degenerated_outside_cycle:
1881 // We have degenerated from outside the cycle, which means something is bad with
1882 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1883 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1884 // we can do the most aggressive degen cycle, which includes processing references and
1885 // class unloading, unless those features are explicitly disabled.
1886 //
1887 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1888 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1889 set_process_references(heuristics()->can_process_references());
1890 set_unload_classes(heuristics()->can_unload_classes());
1891
1892 if (is_traversal_mode()) {
1893 // Not possible to degenerate from here, upgrade to Full GC right away.
1894 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1895 op_degenerated_fail();
1896 return;
1897 }
1898
1899 op_reset();
1900
1901 op_init_mark();
1902 if (cancelled_gc()) {
1903 op_degenerated_fail();
1904 return;
1905 }
1906
1907 case _degenerated_mark:
1908 op_final_mark();
1909 if (cancelled_gc()) {
1910 op_degenerated_fail();
1911 return;
1912 }
1913
1914 op_cleanup();
1915
1916 case _degenerated_evac:
1917 // If heuristics thinks we should do the cycle, this flag would be set,
1918 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
1919 if (is_evacuation_in_progress()) {
1920
1921 // Degeneration under oom-evac protocol might have left some objects in
1922 // collection set un-evacuated. Restart evacuation from the beginning to
1923 // capture all objects. For all the objects that are already evacuated,
1924 // it would be a simple check, which is supposed to be fast. This is also
1925 // safe to do even without degeneration, as CSet iterator is at beginning
1926 // in preparation for evacuation anyway.
1927 //
1928 // Before doing that, we need to make sure we never had any cset-pinned
1929 // regions. This may happen if allocation failure happened when evacuating
1930 // the about-to-be-pinned object, oom-evac protocol left the object in
1931 // the collection set, and then the pin reached the cset region. If we continue
1932 // the cycle here, we would trash the cset and alive objects in it. To avoid
1933 // it, we fail degeneration right away and slide into Full GC to recover.
1934
1935 {
1936 sync_pinned_region_status();
1937 collection_set()->clear_current_index();
1938
1939 ShenandoahHeapRegion* r;
1940 while ((r = collection_set()->next()) != NULL) {
1941 if (r->is_pinned()) {
1942 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1943 op_degenerated_fail();
1944 return;
1945 }
1946 }
1947
1948 collection_set()->clear_current_index();
1949 }
1950
1951 op_stw_evac();
1952 if (cancelled_gc()) {
1953 op_degenerated_fail();
1954 return;
1955 }
1956 }
1957
1958 // If heuristics thinks we should do the cycle, this flag would be set,
1959 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
1960 if (has_forwarded_objects()) {
1961 op_init_updaterefs();
1962 if (cancelled_gc()) {
1963 op_degenerated_fail();
1964 return;
1965 }
1966 }
1967
1968 case _degenerated_updaterefs:
1969 if (has_forwarded_objects()) {
1970 op_final_updaterefs();
1971 if (cancelled_gc()) {
1972 op_degenerated_fail();
1973 return;
1974 }
1975 }
1976
1977 op_cleanup();
1978 break;
1979
1980 default:
1981 ShouldNotReachHere();
1982 }
1983
1984 if (ShenandoahVerify) {
1985 verifier()->verify_after_degenerated();
1986 }
1987
1988 if (VerifyAfterGC) {
1989 Universe::verify();
1990 }
1991
1992 metrics.snap_after();
1993
1994 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
1995 // because that probably means the heap is overloaded and/or fragmented.
1996 if (!metrics.is_good_progress()) {
1997 _progress_last_gc.unset();
1998 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1999 op_degenerated_futile();
2000 } else {
2001 _progress_last_gc.set();
2002 }
2003 }
2004
2005 void ShenandoahHeap::op_degenerated_fail() {
2006 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
2007 shenandoah_policy()->record_degenerated_upgrade_to_full();
2008 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2009 }
2010
2011 void ShenandoahHeap::op_degenerated_futile() {
2012 shenandoah_policy()->record_degenerated_upgrade_to_full();
2013 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2014 }
2015
2016 void ShenandoahHeap::force_satb_flush_all_threads() {
2017 if (!is_concurrent_mark_in_progress() && !is_concurrent_traversal_in_progress()) {
2018 // No need to flush SATBs
2019 return;
2020 }
2021
2022 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2023 ShenandoahThreadLocalData::set_force_satb_flush(t, true);
2024 }
2025 // The threads are not "acquiring" their thread-local data, but it does not
2026 // hurt to "release" the updates here anyway.
2027 OrderAccess::fence();
2028 }
2029
2030 void ShenandoahHeap::set_gc_state_all_threads(char state) {
2031 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2032 ShenandoahThreadLocalData::set_gc_state(t, state);
2033 }
2034 }
2035
2036 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
2037 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
2038 _gc_state.set_cond(mask, value);
2039 set_gc_state_all_threads(_gc_state.raw_value());
2040 }
2041
2042 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
2043 if (has_forwarded_objects()) {
2044 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
2045 } else {
2046 set_gc_state_mask(MARKING, in_progress);
2047 }
2048 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
2049 }
2050
2051 void ShenandoahHeap::set_concurrent_traversal_in_progress(bool in_progress) {
2052 set_gc_state_mask(TRAVERSAL, in_progress);
2053 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
2054 }
2055
2056 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
2057 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
2058 set_gc_state_mask(EVACUATION, in_progress);
2059 }
2060
2061 void ShenandoahHeap::set_concurrent_root_in_progress(bool in_progress) {
2062 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
2063 if (in_progress) {
2064 _concurrent_root_in_progress.set();
2065 } else {
2066 _concurrent_root_in_progress.unset();
2067 }
2068 }
2069
2070 void ShenandoahHeap::ref_processing_init() {
2071 assert(_max_workers > 0, "Sanity");
2072
2073 _ref_processor =
2074 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
2075 ParallelRefProcEnabled, // MT processing
2076 _max_workers, // Degree of MT processing
2077 true, // MT discovery
2078 _max_workers, // Degree of MT discovery
2079 false, // Reference discovery is not atomic
2080 NULL, // No closure, should be installed before use
2081 true); // Scale worker threads
2082
2083 shenandoah_assert_rp_isalive_not_installed();
2084 }
2085
2086 GCTracer* ShenandoahHeap::tracer() {
2087 return shenandoah_policy()->tracer();
2088 }
2089
2090 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
2091 return _free_set->used();
2092 }
2093
2094 bool ShenandoahHeap::try_cancel_gc() {
2095 while (true) {
2096 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
2097 if (prev == CANCELLABLE) return true;
2098 else if (prev == CANCELLED) return false;
2099 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
2100 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
2101 if (Thread::current()->is_Java_thread()) {
2102 // We need to provide a safepoint here, otherwise we might
2103 // spin forever if a SP is pending.
2104 ThreadBlockInVM sp(JavaThread::current());
2105 SpinPause();
2106 }
2107 }
2108 }
2109
2110 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
2111 if (try_cancel_gc()) {
2112 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
2113 log_info(gc)("%s", msg.buffer());
2114 Events::log(Thread::current(), "%s", msg.buffer());
2115 }
2116 }
2117
2118 uint ShenandoahHeap::max_workers() {
2119 return _max_workers;
2120 }
2121
2122 void ShenandoahHeap::stop() {
2123 // The shutdown sequence should be able to terminate when GC is running.
2124
2125 // Step 0. Notify policy to disable event recording.
2126 _shenandoah_policy->record_shutdown();
2127
2128 // Step 1. Notify control thread that we are in shutdown.
2129 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
2130 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
2131 control_thread()->prepare_for_graceful_shutdown();
2132
2133 // Step 2. Notify GC workers that we are cancelling GC.
2134 cancel_gc(GCCause::_shenandoah_stop_vm);
2135
2136 // Step 3. Wait until GC worker exits normally.
2137 control_thread()->stop();
2138
2139 // Step 4. Stop String Dedup thread if it is active
2140 if (ShenandoahStringDedup::is_enabled()) {
2141 ShenandoahStringDedup::stop();
2142 }
2143 }
2144
2145 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
2146 if (!unload_classes()) return;
2147 bool purged_class;
2148
2149 // Unload classes and purge SystemDictionary.
2150 {
2151 ShenandoahGCPhase phase(full_gc ?
2152 ShenandoahPhaseTimings::full_gc_purge_class_unload :
2153 ShenandoahPhaseTimings::purge_class_unload);
2154 purged_class = SystemDictionary::do_unloading(gc_timer());
2155 }
2156
2157 {
2158 ShenandoahGCPhase phase(full_gc ?
2159 ShenandoahPhaseTimings::full_gc_purge_par :
2160 ShenandoahPhaseTimings::purge_par);
2161 ShenandoahIsAliveSelector is_alive;
2162 uint num_workers = _workers->active_workers();
2163 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
2164 _workers->run_task(&unlink_task);
2165 }
2166
2167 {
2168 ShenandoahGCPhase phase(full_gc ?
2169 ShenandoahPhaseTimings::full_gc_purge_cldg :
2170 ShenandoahPhaseTimings::purge_cldg);
2171 ClassLoaderDataGraph::purge();
2172 }
2173 // Resize and verify metaspace
2174 MetaspaceGC::compute_new_size();
2175 MetaspaceUtils::verify_metrics();
2176 }
2177
2178 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
2179 // so they should not have forwarded oops.
2180 // However, we do need to "null" dead oops in the roots, if can not be done
2181 // in concurrent cycles.
2182 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
2183 ShenandoahGCPhase root_phase(full_gc ?
2184 ShenandoahPhaseTimings::full_gc_purge :
2185 ShenandoahPhaseTimings::purge);
2186 uint num_workers = _workers->active_workers();
2187 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
2188 ShenandoahPhaseTimings::full_gc_purge_par :
2189 ShenandoahPhaseTimings::purge_par;
2190 // Cleanup weak roots
2191 ShenandoahGCPhase phase(timing_phase);
2192 phase_timings()->record_workers_start(timing_phase);
2193 if (has_forwarded_objects()) {
2194 if (is_traversal_mode()) {
2195 ShenandoahForwardedIsAliveClosure is_alive;
2196 ShenandoahTraversalUpdateRefsClosure keep_alive;
2197 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahTraversalUpdateRefsClosure>
2198 cleaning_task(&is_alive, &keep_alive, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2199 _workers->run_task(&cleaning_task);
2200 } else {
2201 ShenandoahForwardedIsAliveClosure is_alive;
2202 ShenandoahUpdateRefsClosure keep_alive;
2203 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2204 cleaning_task(&is_alive, &keep_alive, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2205 _workers->run_task(&cleaning_task);
2206 }
2207 } else {
2208 ShenandoahIsAliveClosure is_alive;
2209 #ifdef ASSERT
2210 ShenandoahAssertNotForwardedClosure verify_cl;
2211 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2212 cleaning_task(&is_alive, &verify_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2213 #else
2214 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2215 cleaning_task(&is_alive, &do_nothing_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2216 #endif
2217 _workers->run_task(&cleaning_task);
2218 }
2219 phase_timings()->record_workers_end(timing_phase);
2220 }
2221
2222 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2223 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2224 stw_process_weak_roots(full_gc);
2225 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2226 stw_unload_classes(full_gc);
2227 }
2228 }
2229
2230 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2231 if (is_traversal_mode()) {
2232 set_gc_state_mask(HAS_FORWARDED | UPDATEREFS, cond);
2233 } else {
2234 set_gc_state_mask(HAS_FORWARDED, cond);
2235 }
2236
2237 }
2238
2239 void ShenandoahHeap::set_process_references(bool pr) {
2240 _process_references.set_cond(pr);
2241 }
2242
2243 void ShenandoahHeap::set_unload_classes(bool uc) {
2244 _unload_classes.set_cond(uc);
2245 }
2246
2247 bool ShenandoahHeap::process_references() const {
2248 return _process_references.is_set();
2249 }
2250
2251 bool ShenandoahHeap::unload_classes() const {
2252 return _unload_classes.is_set();
2253 }
2254
2255 address ShenandoahHeap::in_cset_fast_test_addr() {
2256 ShenandoahHeap* heap = ShenandoahHeap::heap();
2257 assert(heap->collection_set() != NULL, "Sanity");
2258 return (address) heap->collection_set()->biased_map_address();
2259 }
2260
2261 address ShenandoahHeap::cancelled_gc_addr() {
2262 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
2263 }
2264
2265 address ShenandoahHeap::gc_state_addr() {
2266 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2267 }
2268
2269 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2270 return Atomic::load_acquire(&_bytes_allocated_since_gc_start);
2271 }
2272
2273 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2274 Atomic::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2275 }
2276
2277 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2278 _degenerated_gc_in_progress.set_cond(in_progress);
2279 }
2280
2281 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2282 _full_gc_in_progress.set_cond(in_progress);
2283 }
2284
2285 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2286 assert (is_full_gc_in_progress(), "should be");
2287 _full_gc_move_in_progress.set_cond(in_progress);
2288 }
2289
2290 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2291 set_gc_state_mask(UPDATEREFS, in_progress);
2292 }
2293
2294 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2295 ShenandoahCodeRoots::register_nmethod(nm);
2296 }
2297
2298 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2299 ShenandoahCodeRoots::unregister_nmethod(nm);
2300 }
2301
2302 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
2303 ShenandoahCodeRoots::flush_nmethod(nm);
2304 }
2305
2306 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2307 heap_region_containing(o)->record_pin();
2308 return o;
2309 }
2310
2311 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2312 heap_region_containing(o)->record_unpin();
2313 }
2314
2315 void ShenandoahHeap::sync_pinned_region_status() {
2316 ShenandoahHeapLocker locker(lock());
2317
2318 for (size_t i = 0; i < num_regions(); i++) {
2319 ShenandoahHeapRegion *r = get_region(i);
2320 if (r->is_active()) {
2321 if (r->is_pinned()) {
2322 if (r->pin_count() == 0) {
2323 r->make_unpinned();
2324 }
2325 } else {
2326 if (r->pin_count() > 0) {
2327 r->make_pinned();
2328 }
2329 }
2330 }
2331 }
2332
2333 assert_pinned_region_status();
2334 }
2335
2336 #ifdef ASSERT
2337 void ShenandoahHeap::assert_pinned_region_status() {
2338 for (size_t i = 0; i < num_regions(); i++) {
2339 ShenandoahHeapRegion* r = get_region(i);
2340 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2341 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2342 }
2343 }
2344 #endif
2345
2346 GCTimer* ShenandoahHeap::gc_timer() const {
2347 return _gc_timer;
2348 }
2349
2350 void ShenandoahHeap::prepare_concurrent_roots() {
2351 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2352 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
2353 set_concurrent_root_in_progress(true);
2354 }
2355 }
2356
2357 void ShenandoahHeap::prepare_concurrent_unloading() {
2358 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2359 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2360 _unloader.prepare();
2361 }
2362 }
2363
2364 void ShenandoahHeap::finish_concurrent_unloading() {
2365 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2366 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2367 _unloader.finish();
2368 }
2369 }
2370
2371 #ifdef ASSERT
2372 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2373 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2374
2375 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2376 if (UseDynamicNumberOfGCThreads ||
2377 (FLAG_IS_DEFAULT(ParallelGCThreads) && ForceDynamicNumberOfGCThreads)) {
2378 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2379 } else {
2380 // Use ParallelGCThreads inside safepoints
2381 assert(nworkers == ParallelGCThreads, "Use ParalleGCThreads within safepoints");
2382 }
2383 } else {
2384 if (UseDynamicNumberOfGCThreads ||
2385 (FLAG_IS_DEFAULT(ConcGCThreads) && ForceDynamicNumberOfGCThreads)) {
2386 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2387 } else {
2388 // Use ConcGCThreads outside safepoints
2389 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2390 }
2391 }
2392 }
2393 #endif
2394
2395 ShenandoahVerifier* ShenandoahHeap::verifier() {
2396 guarantee(ShenandoahVerify, "Should be enabled");
2397 assert (_verifier != NULL, "sanity");
2398 return _verifier;
2399 }
2400
2401 template<class T>
2402 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2403 private:
2404 T cl;
2405 ShenandoahHeap* _heap;
2406 ShenandoahRegionIterator* _regions;
2407 bool _concurrent;
2408 public:
2409 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2410 AbstractGangTask("Concurrent Update References Task"),
2411 cl(T()),
2412 _heap(ShenandoahHeap::heap()),
2413 _regions(regions),
2414 _concurrent(concurrent) {
2415 }
2416
2417 void work(uint worker_id) {
2418 if (_concurrent) {
2419 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2420 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2421 do_work();
2422 } else {
2423 ShenandoahParallelWorkerSession worker_session(worker_id);
2424 do_work();
2425 }
2426 }
2427
2428 private:
2429 void do_work() {
2430 ShenandoahHeapRegion* r = _regions->next();
2431 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2432 while (r != NULL) {
2433 HeapWord* top_at_start_ur = r->concurrent_iteration_safe_limit();
2434 assert (top_at_start_ur >= r->bottom(), "sanity");
2435 if (r->is_active() && !r->is_cset()) {
2436 _heap->marked_object_oop_iterate(r, &cl, top_at_start_ur);
2437 }
2438 if (ShenandoahPacing) {
2439 _heap->pacer()->report_updaterefs(pointer_delta(top_at_start_ur, r->bottom()));
2440 }
2441 if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
2442 return;
2443 }
2444 r = _regions->next();
2445 }
2446 }
2447 };
2448
2449 void ShenandoahHeap::update_heap_references(bool concurrent) {
2450 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
2451 workers()->run_task(&task);
2452 }
2453
2454 void ShenandoahHeap::op_init_updaterefs() {
2455 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2456
2457 set_evacuation_in_progress(false);
2458
2459 {
2460 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_retire_gclabs);
2461 retire_and_reset_gclabs();
2462 }
2463
2464 if (ShenandoahVerify) {
2465 if (!is_degenerated_gc_in_progress()) {
2466 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2467 }
2468 verifier()->verify_before_updaterefs();
2469 }
2470
2471 set_update_refs_in_progress(true);
2472
2473 {
2474 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_prepare);
2475
2476 make_parsable(true);
2477 for (uint i = 0; i < num_regions(); i++) {
2478 ShenandoahHeapRegion* r = get_region(i);
2479 r->set_concurrent_iteration_safe_limit(r->top());
2480 }
2481
2482 // Reset iterator.
2483 _update_refs_iterator.reset();
2484 }
2485
2486 if (ShenandoahPacing) {
2487 pacer()->setup_for_updaterefs();
2488 }
2489 }
2490
2491 void ShenandoahHeap::op_final_updaterefs() {
2492 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2493
2494 finish_concurrent_unloading();
2495
2496 // Check if there is left-over work, and finish it
2497 if (_update_refs_iterator.has_next()) {
2498 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2499
2500 // Finish updating references where we left off.
2501 clear_cancelled_gc();
2502 update_heap_references(false);
2503 }
2504
2505 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2506 // everything. On degenerated paths, cancelled gc would not be set anyway.
2507 if (cancelled_gc()) {
2508 clear_cancelled_gc();
2509 }
2510 assert(!cancelled_gc(), "Should have been done right before");
2511
2512 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2513 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2514 }
2515
2516 if (is_degenerated_gc_in_progress()) {
2517 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2518 } else {
2519 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2520 }
2521
2522 // Has to be done before cset is clear
2523 if (ShenandoahVerify) {
2524 verifier()->verify_roots_in_to_space();
2525 }
2526
2527 // Drop unnecessary "pinned" state from regions that does not have CP marks
2528 // anymore, as this would allow trashing them below.
2529 {
2530 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_sync_pinned);
2531 sync_pinned_region_status();
2532 }
2533
2534 {
2535 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2536 trash_cset_regions();
2537 }
2538
2539 set_has_forwarded_objects(false);
2540 set_update_refs_in_progress(false);
2541
2542 if (ShenandoahVerify) {
2543 verifier()->verify_after_updaterefs();
2544 }
2545
2546 if (VerifyAfterGC) {
2547 Universe::verify();
2548 }
2549
2550 {
2551 ShenandoahHeapLocker locker(lock());
2552 _free_set->rebuild();
2553 }
2554 }
2555
2556 #ifdef ASSERT
2557 void ShenandoahHeap::assert_heaplock_owned_by_current_thread() {
2558 _lock.assert_owned_by_current_thread();
2559 }
2560
2561 void ShenandoahHeap::assert_heaplock_not_owned_by_current_thread() {
2562 _lock.assert_not_owned_by_current_thread();
2563 }
2564
2565 void ShenandoahHeap::assert_heaplock_or_safepoint() {
2566 _lock.assert_owned_by_current_thread_or_safepoint();
2567 }
2568 #endif
2569
2570 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2571 print_on(st);
2572 print_heap_regions_on(st);
2573 }
2574
2575 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2576 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2577
2578 size_t regions_from = _bitmap_regions_per_slice * slice;
2579 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2580 for (size_t g = regions_from; g < regions_to; g++) {
2581 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2582 if (skip_self && g == r->region_number()) continue;
2583 if (get_region(g)->is_committed()) {
2584 return true;
2585 }
2586 }
2587 return false;
2588 }
2589
2590 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2591 assert_heaplock_owned_by_current_thread();
2592
2593 // Bitmaps in special regions do not need commits
2594 if (_bitmap_region_special) {
2595 return true;
2596 }
2597
2598 if (is_bitmap_slice_committed(r, true)) {
2599 // Some other region from the group is already committed, meaning the bitmap
2600 // slice is already committed, we exit right away.
2601 return true;
2602 }
2603
2604 // Commit the bitmap slice:
2605 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2606 size_t off = _bitmap_bytes_per_slice * slice;
2607 size_t len = _bitmap_bytes_per_slice;
2608 if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) {
2609 return false;
2610 }
2611 return true;
2612 }
2613
2614 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2615 assert_heaplock_owned_by_current_thread();
2616
2617 // Bitmaps in special regions do not need uncommits
2618 if (_bitmap_region_special) {
2619 return true;
2620 }
2621
2622 if (is_bitmap_slice_committed(r, true)) {
2623 // Some other region from the group is still committed, meaning the bitmap
2624 // slice is should stay committed, exit right away.
2625 return true;
2626 }
2627
2628 // Uncommit the bitmap slice:
2629 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2630 size_t off = _bitmap_bytes_per_slice * slice;
2631 size_t len = _bitmap_bytes_per_slice;
2632 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2633 return false;
2634 }
2635 return true;
2636 }
2637
2638 void ShenandoahHeap::safepoint_synchronize_begin() {
2639 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2640 SuspendibleThreadSet::synchronize();
2641 }
2642 }
2643
2644 void ShenandoahHeap::safepoint_synchronize_end() {
2645 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2646 SuspendibleThreadSet::desynchronize();
2647 }
2648 }
2649
2650 void ShenandoahHeap::vmop_entry_init_mark() {
2651 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2652 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2653 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
2654
2655 try_inject_alloc_failure();
2656 VM_ShenandoahInitMark op;
2657 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2658 }
2659
2660 void ShenandoahHeap::vmop_entry_final_mark() {
2661 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2662 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2663 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
2664
2665 try_inject_alloc_failure();
2666 VM_ShenandoahFinalMarkStartEvac op;
2667 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2668 }
2669
2670 void ShenandoahHeap::vmop_entry_final_evac() {
2671 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2672 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2673 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_gross);
2674
2675 VM_ShenandoahFinalEvac op;
2676 VMThread::execute(&op); // jump to entry_final_evac under safepoint
2677 }
2678
2679 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2680 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2681 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2682 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
2683
2684 try_inject_alloc_failure();
2685 VM_ShenandoahInitUpdateRefs op;
2686 VMThread::execute(&op);
2687 }
2688
2689 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2690 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2691 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2692 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
2693
2694 try_inject_alloc_failure();
2695 VM_ShenandoahFinalUpdateRefs op;
2696 VMThread::execute(&op);
2697 }
2698
2699 void ShenandoahHeap::vmop_entry_init_traversal() {
2700 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2701 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2702 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc_gross);
2703
2704 try_inject_alloc_failure();
2705 VM_ShenandoahInitTraversalGC op;
2706 VMThread::execute(&op);
2707 }
2708
2709 void ShenandoahHeap::vmop_entry_final_traversal() {
2710 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2711 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2712 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc_gross);
2713
2714 try_inject_alloc_failure();
2715 VM_ShenandoahFinalTraversalGC op;
2716 VMThread::execute(&op);
2717 }
2718
2719 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2720 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2721 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2722 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
2723
2724 try_inject_alloc_failure();
2725 VM_ShenandoahFullGC op(cause);
2726 VMThread::execute(&op);
2727 }
2728
2729 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2730 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2731 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2732 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
2733
2734 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2735 VMThread::execute(°enerated_gc);
2736 }
2737
2738 void ShenandoahHeap::entry_init_mark() {
2739 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2740 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
2741 const char* msg = init_mark_event_message();
2742 GCTraceTime(Info, gc) time(msg, gc_timer());
2743 EventMark em("%s", msg);
2744
2745 ShenandoahWorkerScope scope(workers(),
2746 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2747 "init marking");
2748
2749 op_init_mark();
2750 }
2751
2752 void ShenandoahHeap::entry_final_mark() {
2753 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2754 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
2755 const char* msg = final_mark_event_message();
2756 GCTraceTime(Info, gc) time(msg, gc_timer());
2757 EventMark em("%s", msg);
2758
2759 ShenandoahWorkerScope scope(workers(),
2760 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2761 "final marking");
2762
2763 op_final_mark();
2764 }
2765
2766 void ShenandoahHeap::entry_final_evac() {
2767 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2768 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac);
2769 static const char* msg = "Pause Final Evac";
2770 GCTraceTime(Info, gc) time(msg, gc_timer());
2771 EventMark em("%s", msg);
2772
2773 op_final_evac();
2774 }
2775
2776 void ShenandoahHeap::entry_init_updaterefs() {
2777 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2778 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
2779
2780 static const char* msg = "Pause Init Update Refs";
2781 GCTraceTime(Info, gc) time(msg, gc_timer());
2782 EventMark em("%s", msg);
2783
2784 // No workers used in this phase, no setup required
2785
2786 op_init_updaterefs();
2787 }
2788
2789 void ShenandoahHeap::entry_final_updaterefs() {
2790 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2791 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
2792
2793 static const char* msg = "Pause Final Update Refs";
2794 GCTraceTime(Info, gc) time(msg, gc_timer());
2795 EventMark em("%s", msg);
2796
2797 ShenandoahWorkerScope scope(workers(),
2798 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2799 "final reference update");
2800
2801 op_final_updaterefs();
2802 }
2803
2804 void ShenandoahHeap::entry_init_traversal() {
2805 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2806 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc);
2807
2808 static const char* msg = init_traversal_event_message();
2809 GCTraceTime(Info, gc) time(msg, gc_timer());
2810 EventMark em("%s", msg);
2811
2812 ShenandoahWorkerScope scope(workers(),
2813 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2814 "init traversal");
2815
2816 op_init_traversal();
2817 }
2818
2819 void ShenandoahHeap::entry_final_traversal() {
2820 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2821 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc);
2822
2823 static const char* msg = final_traversal_event_message();
2824 GCTraceTime(Info, gc) time(msg, gc_timer());
2825 EventMark em("%s", msg);
2826
2827 ShenandoahWorkerScope scope(workers(),
2828 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2829 "final traversal");
2830
2831 op_final_traversal();
2832 }
2833
2834 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2835 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2836 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
2837
2838 static const char* msg = "Pause Full";
2839 GCTraceTime(Info, gc) time(msg, gc_timer(), cause, true);
2840 EventMark em("%s", msg);
2841
2842 ShenandoahWorkerScope scope(workers(),
2843 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2844 "full gc");
2845
2846 op_full(cause);
2847 }
2848
2849 void ShenandoahHeap::entry_degenerated(int point) {
2850 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2851 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
2852
2853 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2854 const char* msg = degen_event_message(dpoint);
2855 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2856 EventMark em("%s", msg);
2857
2858 ShenandoahWorkerScope scope(workers(),
2859 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2860 "stw degenerated gc");
2861
2862 set_degenerated_gc_in_progress(true);
2863 op_degenerated(dpoint);
2864 set_degenerated_gc_in_progress(false);
2865 }
2866
2867 void ShenandoahHeap::entry_mark() {
2868 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2869
2870 const char* msg = conc_mark_event_message();
2871 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2872 EventMark em("%s", msg);
2873
2874 ShenandoahWorkerScope scope(workers(),
2875 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2876 "concurrent marking");
2877
2878 try_inject_alloc_failure();
2879 op_mark();
2880 }
2881
2882 void ShenandoahHeap::entry_evac() {
2883 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
2884 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2885
2886 static const char* msg = "Concurrent evacuation";
2887 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2888 EventMark em("%s", msg);
2889
2890 ShenandoahWorkerScope scope(workers(),
2891 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2892 "concurrent evacuation");
2893
2894 try_inject_alloc_failure();
2895 op_conc_evac();
2896 }
2897
2898 void ShenandoahHeap::entry_updaterefs() {
2899 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
2900
2901 static const char* msg = "Concurrent update references";
2902 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2903 EventMark em("%s", msg);
2904
2905 ShenandoahWorkerScope scope(workers(),
2906 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2907 "concurrent reference update");
2908
2909 try_inject_alloc_failure();
2910 op_updaterefs();
2911 }
2912
2913 void ShenandoahHeap::entry_roots() {
2914 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_roots);
2915
2916 static const char* msg = "Concurrent roots processing";
2917 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2918 EventMark em("%s", msg);
2919
2920 ShenandoahWorkerScope scope(workers(),
2921 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2922 "concurrent root processing");
2923
2924 try_inject_alloc_failure();
2925 op_roots();
2926 }
2927
2928 void ShenandoahHeap::entry_cleanup() {
2929 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup);
2930
2931 static const char* msg = "Concurrent cleanup";
2932 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2933 EventMark em("%s", msg);
2934
2935 // This phase does not use workers, no need for setup
2936
2937 try_inject_alloc_failure();
2938 op_cleanup();
2939 }
2940
2941 void ShenandoahHeap::entry_reset() {
2942 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset);
2943
2944 static const char* msg = "Concurrent reset";
2945 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2946 EventMark em("%s", msg);
2947
2948 ShenandoahWorkerScope scope(workers(),
2949 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2950 "concurrent reset");
2951
2952 try_inject_alloc_failure();
2953 op_reset();
2954 }
2955
2956 void ShenandoahHeap::entry_preclean() {
2957 if (ShenandoahPreclean && process_references()) {
2958 static const char* msg = "Concurrent precleaning";
2959 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2960 EventMark em("%s", msg);
2961
2962 ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
2963
2964 ShenandoahWorkerScope scope(workers(),
2965 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2966 "concurrent preclean",
2967 /* check_workers = */ false);
2968
2969 try_inject_alloc_failure();
2970 op_preclean();
2971 }
2972 }
2973
2974 void ShenandoahHeap::entry_traversal() {
2975 static const char* msg = conc_traversal_event_message();
2976 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2977 EventMark em("%s", msg);
2978
2979 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2980
2981 ShenandoahWorkerScope scope(workers(),
2982 ShenandoahWorkerPolicy::calc_workers_for_conc_traversal(),
2983 "concurrent traversal");
2984
2985 try_inject_alloc_failure();
2986 op_traversal();
2987 }
2988
2989 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2990 static const char *msg = "Concurrent uncommit";
2991 GCTraceTime(Info, gc) time(msg, NULL, GCCause::_no_gc, true);
2992 EventMark em("%s", msg);
2993
2994 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit);
2995
2996 op_uncommit(shrink_before);
2997 }
2998
2999 void ShenandoahHeap::try_inject_alloc_failure() {
3000 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
3001 _inject_alloc_failure.set();
3002 os::naked_short_sleep(1);
3003 if (cancelled_gc()) {
3004 log_info(gc)("Allocation failure was successfully injected");
3005 }
3006 }
3007 }
3008
3009 bool ShenandoahHeap::should_inject_alloc_failure() {
3010 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
3011 }
3012
3013 void ShenandoahHeap::initialize_serviceability() {
3014 _memory_pool = new ShenandoahMemoryPool(this);
3015 _cycle_memory_manager.add_pool(_memory_pool);
3016 _stw_memory_manager.add_pool(_memory_pool);
3017 }
3018
3019 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
3020 GrowableArray<GCMemoryManager*> memory_managers(2);
3021 memory_managers.append(&_cycle_memory_manager);
3022 memory_managers.append(&_stw_memory_manager);
3023 return memory_managers;
3024 }
3025
3026 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
3027 GrowableArray<MemoryPool*> memory_pools(1);
3028 memory_pools.append(_memory_pool);
3029 return memory_pools;
3030 }
3031
3032 MemoryUsage ShenandoahHeap::memory_usage() {
3033 return _memory_pool->get_memory_usage();
3034 }
3035
3036 void ShenandoahHeap::enter_evacuation() {
3037 _oom_evac_handler.enter_evacuation();
3038 }
3039
3040 void ShenandoahHeap::leave_evacuation() {
3041 _oom_evac_handler.leave_evacuation();
3042 }
3043
3044 ShenandoahRegionIterator::ShenandoahRegionIterator() :
3045 _heap(ShenandoahHeap::heap()),
3046 _index(0) {}
3047
3048 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
3049 _heap(heap),
3050 _index(0) {}
3051
3052 void ShenandoahRegionIterator::reset() {
3053 _index = 0;
3054 }
3055
3056 bool ShenandoahRegionIterator::has_next() const {
3057 return _index < _heap->num_regions();
3058 }
3059
3060 char ShenandoahHeap::gc_state() const {
3061 return _gc_state.raw_value();
3062 }
3063
3064 void ShenandoahHeap::deduplicate_string(oop str) {
3065 assert(java_lang_String::is_instance(str), "invariant");
3066
3067 if (ShenandoahStringDedup::is_enabled()) {
3068 ShenandoahStringDedup::deduplicate(str);
3069 }
3070 }
3071
3072 const char* ShenandoahHeap::init_mark_event_message() const {
3073 bool update_refs = has_forwarded_objects();
3074 bool proc_refs = process_references();
3075 bool unload_cls = unload_classes();
3076
3077 if (update_refs && proc_refs && unload_cls) {
3078 return "Pause Init Mark (update refs) (process weakrefs) (unload classes)";
3079 } else if (update_refs && proc_refs) {
3080 return "Pause Init Mark (update refs) (process weakrefs)";
3081 } else if (update_refs && unload_cls) {
3082 return "Pause Init Mark (update refs) (unload classes)";
3083 } else if (proc_refs && unload_cls) {
3084 return "Pause Init Mark (process weakrefs) (unload classes)";
3085 } else if (update_refs) {
3086 return "Pause Init Mark (update refs)";
3087 } else if (proc_refs) {
3088 return "Pause Init Mark (process weakrefs)";
3089 } else if (unload_cls) {
3090 return "Pause Init Mark (unload classes)";
3091 } else {
3092 return "Pause Init Mark";
3093 }
3094 }
3095
3096 const char* ShenandoahHeap::final_mark_event_message() const {
3097 bool update_refs = has_forwarded_objects();
3098 bool proc_refs = process_references();
3099 bool unload_cls = unload_classes();
3100
3101 if (update_refs && proc_refs && unload_cls) {
3102 return "Pause Final Mark (update refs) (process weakrefs) (unload classes)";
3103 } else if (update_refs && proc_refs) {
3104 return "Pause Final Mark (update refs) (process weakrefs)";
3105 } else if (update_refs && unload_cls) {
3106 return "Pause Final Mark (update refs) (unload classes)";
3107 } else if (proc_refs && unload_cls) {
3108 return "Pause Final Mark (process weakrefs) (unload classes)";
3109 } else if (update_refs) {
3110 return "Pause Final Mark (update refs)";
3111 } else if (proc_refs) {
3112 return "Pause Final Mark (process weakrefs)";
3113 } else if (unload_cls) {
3114 return "Pause Final Mark (unload classes)";
3115 } else {
3116 return "Pause Final Mark";
3117 }
3118 }
3119
3120 const char* ShenandoahHeap::conc_mark_event_message() const {
3121 bool update_refs = has_forwarded_objects();
3122 bool proc_refs = process_references();
3123 bool unload_cls = unload_classes();
3124
3125 if (update_refs && proc_refs && unload_cls) {
3126 return "Concurrent marking (update refs) (process weakrefs) (unload classes)";
3127 } else if (update_refs && proc_refs) {
3128 return "Concurrent marking (update refs) (process weakrefs)";
3129 } else if (update_refs && unload_cls) {
3130 return "Concurrent marking (update refs) (unload classes)";
3131 } else if (proc_refs && unload_cls) {
3132 return "Concurrent marking (process weakrefs) (unload classes)";
3133 } else if (update_refs) {
3134 return "Concurrent marking (update refs)";
3135 } else if (proc_refs) {
3136 return "Concurrent marking (process weakrefs)";
3137 } else if (unload_cls) {
3138 return "Concurrent marking (unload classes)";
3139 } else {
3140 return "Concurrent marking";
3141 }
3142 }
3143
3144 const char* ShenandoahHeap::init_traversal_event_message() const {
3145 bool proc_refs = process_references();
3146 bool unload_cls = unload_classes();
3147
3148 if (proc_refs && unload_cls) {
3149 return "Pause Init Traversal (process weakrefs) (unload classes)";
3150 } else if (proc_refs) {
3151 return "Pause Init Traversal (process weakrefs)";
3152 } else if (unload_cls) {
3153 return "Pause Init Traversal (unload classes)";
3154 } else {
3155 return "Pause Init Traversal";
3156 }
3157 }
3158
3159 const char* ShenandoahHeap::final_traversal_event_message() const {
3160 bool proc_refs = process_references();
3161 bool unload_cls = unload_classes();
3162
3163 if (proc_refs && unload_cls) {
3164 return "Pause Final Traversal (process weakrefs) (unload classes)";
3165 } else if (proc_refs) {
3166 return "Pause Final Traversal (process weakrefs)";
3167 } else if (unload_cls) {
3168 return "Pause Final Traversal (unload classes)";
3169 } else {
3170 return "Pause Final Traversal";
3171 }
3172 }
3173
3174 const char* ShenandoahHeap::conc_traversal_event_message() const {
3175 bool proc_refs = process_references();
3176 bool unload_cls = unload_classes();
3177
3178 if (proc_refs && unload_cls) {
3179 return "Concurrent Traversal (process weakrefs) (unload classes)";
3180 } else if (proc_refs) {
3181 return "Concurrent Traversal (process weakrefs)";
3182 } else if (unload_cls) {
3183 return "Concurrent Traversal (unload classes)";
3184 } else {
3185 return "Concurrent Traversal";
3186 }
3187 }
3188
3189 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
3190 switch (point) {
3191 case _degenerated_unset:
3192 return "Pause Degenerated GC (<UNSET>)";
3193 case _degenerated_traversal:
3194 return "Pause Degenerated GC (Traversal)";
3195 case _degenerated_outside_cycle:
3196 return "Pause Degenerated GC (Outside of Cycle)";
3197 case _degenerated_mark:
3198 return "Pause Degenerated GC (Mark)";
3199 case _degenerated_evac:
3200 return "Pause Degenerated GC (Evacuation)";
3201 case _degenerated_updaterefs:
3202 return "Pause Degenerated GC (Update Refs)";
3203 default:
3204 ShouldNotReachHere();
3205 return "ERROR";
3206 }
3207 }
3208
3209 jushort* ShenandoahHeap::get_liveness_cache(uint worker_id) {
3210 #ifdef ASSERT
3211 assert(_liveness_cache != NULL, "sanity");
3212 assert(worker_id < _max_workers, "sanity");
3213 for (uint i = 0; i < num_regions(); i++) {
3214 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
3215 }
3216 #endif
3217 return _liveness_cache[worker_id];
3218 }
3219
3220 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
3221 assert(worker_id < _max_workers, "sanity");
3222 assert(_liveness_cache != NULL, "sanity");
3223 jushort* ld = _liveness_cache[worker_id];
3224 for (uint i = 0; i < num_regions(); i++) {
3225 ShenandoahHeapRegion* r = get_region(i);
3226 jushort live = ld[i];
3227 if (live > 0) {
3228 r->increase_live_data_gc_words(live);
3229 ld[i] = 0;
3230 }
3231 }
3232 }