1 /*
2 * Copyright (c) 2013, 2017, Red Hat, Inc. and/or its affiliates.
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
27 #include "gc/shared/gcTimer.hpp"
28 #include "gc/shared/gcTraceTime.inline.hpp"
29 #include "gc/shared/parallelCleaning.hpp"
30
31 #include "gc/shenandoah/brooksPointer.hpp"
32 #include "gc/shenandoah/shenandoahAllocTracker.hpp"
33 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
34 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
35 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
36 #include "gc/shenandoah/shenandoahConcurrentMark.hpp"
37 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
38 #include "gc/shenandoah/shenandoahConcurrentThread.hpp"
39 #include "gc/shenandoah/shenandoahFreeSet.hpp"
40 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
41 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
42 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
43 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
44 #include "gc/shenandoah/shenandoahMarkCompact.hpp"
45 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
46 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
47 #include "gc/shenandoah/shenandoahPartialGC.hpp"
48 #include "gc/shenandoah/shenandoahRootProcessor.hpp"
49 #include "gc/shenandoah/shenandoahStringDedup.hpp"
50 #include "gc/shenandoah/shenandoahUtils.hpp"
51 #include "gc/shenandoah/shenandoahVerifier.hpp"
52 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
53 #include "gc/shenandoah/vm_operations_shenandoah.hpp"
54
55 #include "runtime/vmThread.hpp"
56 #include "services/mallocTracker.hpp"
57
58 ShenandoahUpdateRefsClosure::ShenandoahUpdateRefsClosure() : _heap(ShenandoahHeap::heap()) {}
59
60 #ifdef ASSERT
61 template <class T>
62 void ShenandoahAssertToSpaceClosure::do_oop_nv(T* p) {
63 T o = oopDesc::load_heap_oop(p);
64 if (! oopDesc::is_null(o)) {
65 oop obj = oopDesc::decode_heap_oop_not_null(o);
66 assert(oopDesc::unsafe_equals(obj, ShenandoahBarrierSet::resolve_oop_static_not_null(obj)),
67 "need to-space object here obj: "PTR_FORMAT" , rb(obj): "PTR_FORMAT", p: "PTR_FORMAT,
68 p2i(obj), p2i(ShenandoahBarrierSet::resolve_oop_static_not_null(obj)), p2i(p));
69 }
70 }
71
72 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_nv(p); }
73 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_nv(p); }
74 #endif
75
76 const char* ShenandoahHeap::name() const {
77 return "Shenandoah";
78 }
79
80 class ShenandoahPretouchTask : public AbstractGangTask {
81 private:
82 ShenandoahHeapRegionSet* _regions;
83 const size_t _bitmap_size;
84 const size_t _page_size;
85 char* _bitmap_base;
86 public:
87 ShenandoahPretouchTask(ShenandoahHeapRegionSet* regions,
88 char* bitmap_base, size_t bitmap_size,
89 size_t page_size) :
90 AbstractGangTask("Shenandoah PreTouch",
91 Universe::is_fully_initialized() ? GCId::current_raw() :
92 // During VM initialization there is
93 // no GC cycle that this task can be
94 // associated with.
95 GCId::undefined()),
96 _bitmap_base(bitmap_base),
97 _regions(regions),
98 _bitmap_size(bitmap_size),
99 _page_size(page_size) {
100 _regions->clear_current_index();
101 };
102
103 virtual void work(uint worker_id) {
104 ShenandoahHeapRegion* r = _regions->claim_next();
105 while (r != NULL) {
106 log_trace(gc, heap)("Pretouch region " SIZE_FORMAT ": " PTR_FORMAT " -> " PTR_FORMAT,
107 r->region_number(), p2i(r->bottom()), p2i(r->end()));
108 os::pretouch_memory(r->bottom(), r->end(), _page_size);
109
110 size_t start = r->region_number() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
111 size_t end = (r->region_number() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
112 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
113
114 log_trace(gc, heap)("Pretouch bitmap under region " SIZE_FORMAT ": " PTR_FORMAT " -> " PTR_FORMAT,
115 r->region_number(), p2i(_bitmap_base + start), p2i(_bitmap_base + end));
116 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
117
118 r = _regions->claim_next();
119 }
120 }
121 };
122
123 jint ShenandoahHeap::initialize() {
124 CollectedHeap::pre_initialize();
125
126 BrooksPointer::initial_checks();
127
128 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
129 size_t max_byte_size = collector_policy()->max_heap_byte_size();
130 size_t heap_alignment = collector_policy()->heap_alignment();
131
132 if (ShenandoahAlwaysPreTouch) {
133 // Enabled pre-touch means the entire heap is committed right away.
134 init_byte_size = max_byte_size;
135 }
136
137 Universe::check_alignment(max_byte_size,
138 ShenandoahHeapRegion::region_size_bytes(),
139 "shenandoah heap");
140 Universe::check_alignment(init_byte_size,
141 ShenandoahHeapRegion::region_size_bytes(),
142 "shenandoah heap");
143
144 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
145 heap_alignment);
146 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*) (heap_rs.base() + heap_rs.size()));
147
148 set_barrier_set(new ShenandoahBarrierSet(this));
149 ReservedSpace pgc_rs = heap_rs.first_part(max_byte_size);
150
151 _num_regions = max_byte_size / ShenandoahHeapRegion::region_size_bytes();
152 size_t num_committed_regions = init_byte_size / ShenandoahHeapRegion::region_size_bytes();
153 _initial_size = num_committed_regions * ShenandoahHeapRegion::region_size_bytes();
154 _committed = _initial_size;
155
156 log_info(gc, heap)("Initialize Shenandoah heap with initial size " SIZE_FORMAT " bytes", init_byte_size);
157 if (!os::commit_memory(pgc_rs.base(), _initial_size, false)) {
158 vm_exit_out_of_memory(_initial_size, OOM_MMAP_ERROR, "Shenandoah failed to initialize heap");
159 }
160
161 size_t reg_size_words = ShenandoahHeapRegion::region_size_words();
162
163 _ordered_regions = new ShenandoahHeapRegionSet(_num_regions);
164 _free_regions = new ShenandoahFreeSet(_ordered_regions, _num_regions);
165
166 _collection_set = new ShenandoahCollectionSet(this, (HeapWord*)pgc_rs.base());
167
168 _top_at_mark_starts_base = NEW_C_HEAP_ARRAY(HeapWord*, _num_regions, mtGC);
169 _top_at_mark_starts = _top_at_mark_starts_base -
170 ((uintx) pgc_rs.base() >> ShenandoahHeapRegion::region_size_bytes_shift());
171
172
173 {
174 ShenandoahHeapLocker locker(lock());
175 for (size_t i = 0; i < _num_regions; i++) {
176 ShenandoahHeapRegion* r = new ShenandoahHeapRegion(this,
177 (HeapWord*) pgc_rs.base() + reg_size_words * i,
178 reg_size_words,
179 i,
180 i < num_committed_regions);
181
182 _top_at_mark_starts_base[i] = r->bottom();
183
184 // Add to ordered regions first.
185 // We use the active size of ordered regions as the number of active regions in heap,
186 // free set and collection set use the number to assert the correctness of incoming regions.
187 _ordered_regions->add_region(r);
188 _free_regions->add_region(r);
189 assert(!collection_set()->is_in(i), "New region should not be in collection set");
190 }
191 }
192
193 assert(_ordered_regions->active_regions() == _num_regions, "Must match");
194 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
195 "misaligned heap: "PTR_FORMAT, p2i(base()));
196
197 LogTarget(Trace, gc, region) lt;
198 if (lt.is_enabled()) {
199 ResourceMark rm;
200 LogStream ls(lt);
201 log_trace(gc, region)("All Regions");
202 _ordered_regions->print_on(&ls);
203 log_trace(gc, region)("Free Regions");
204 _free_regions->print_on(&ls);
205 }
206
207 _recycled_regions = NEW_C_HEAP_ARRAY(size_t, _num_regions, mtGC);
208
209 // The call below uses stuff (the SATB* things) that are in G1, but probably
210 // belong into a shared location.
211 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
212 SATB_Q_FL_lock,
213 20 /*G1SATBProcessCompletedThreshold */,
214 Shared_SATB_Q_lock);
215
216 // Reserve space for prev and next bitmap.
217 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
218 _heap_region = MemRegion((HeapWord*) heap_rs.base(), heap_rs.size() / HeapWordSize);
219
220 size_t bitmap_bytes_per_region = _bitmap_size / _num_regions;
221 _bitmap_words_per_region = bitmap_bytes_per_region / HeapWordSize;
222
223 guarantee(bitmap_bytes_per_region != 0,
224 "Bitmap bytes per region should not be zero");
225 guarantee(is_power_of_2(bitmap_bytes_per_region),
226 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
227 guarantee((bitmap_bytes_per_region % os::vm_page_size()) == 0,
228 "Bitmap bytes per region should be page-granular: bpr = " SIZE_FORMAT ", page size = %d",
229 bitmap_bytes_per_region, os::vm_page_size());
230 guarantee(is_power_of_2(_bitmap_words_per_region),
231 "Bitmap words per region Should be power of two: " SIZE_FORMAT, _bitmap_words_per_region);
232
233 size_t bitmap_page_size = UseLargePages && (bitmap_bytes_per_region >= (size_t)os::large_page_size()) ?
234 (size_t)os::large_page_size() : (size_t)os::vm_page_size();
235
236 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
237 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
238 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
239
240 {
241 ShenandoahHeapLocker locker(lock());
242 for (size_t i = 0; i < _num_regions; i++) {
243 ShenandoahHeapRegion* r = _ordered_regions->get(i);
244 if (r->is_committed()) {
245 commit_bitmaps(r);
246 }
247 }
248 }
249
250 size_t page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
251
252 if (ShenandoahVerify) {
253 ReservedSpace verify_bitmap(_bitmap_size, page_size);
254 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), false,
255 "couldn't allocate verification bitmap");
256 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
257 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
258 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
259 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
260 }
261
262 if (ShenandoahAlwaysPreTouch) {
263 assert (!AlwaysPreTouch, "Should have been overridden");
264
265 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
266 // before initialize() below zeroes it with initializing thread. For any given region,
267 // we touch the region and the corresponding bitmaps from the same thread.
268
269 log_info(gc, heap)("Parallel pretouch " SIZE_FORMAT " regions with " SIZE_FORMAT " byte pages",
270 _ordered_regions->count(), page_size);
271 ShenandoahPretouchTask cl(_ordered_regions, bitmap.base(), _bitmap_size, page_size);
272 _workers->run_task(&cl);
273 }
274
275 _mark_bit_map.initialize(_heap_region, _bitmap_region);
276
277 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
278 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
279 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
280 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
281 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
282
283 if (UseShenandoahMatrix) {
284 _connection_matrix = new ShenandoahConnectionMatrix(_num_regions);
285 } else {
286 _connection_matrix = NULL;
287 }
288
289 _partial_gc = _shenandoah_policy->can_do_partial_gc() ?
290 new ShenandoahPartialGC(this, _num_regions) :
291 NULL;
292
293 _monitoring_support = new ShenandoahMonitoringSupport(this);
294
295 _phase_timings = new ShenandoahPhaseTimings();
296
297 if (ShenandoahAllocationTrace) {
298 _alloc_tracker = new ShenandoahAllocTracker();
299 }
300
301 ShenandoahStringDedup::initialize();
302
303 _concurrent_gc_thread = new ShenandoahConcurrentThread();
304
305 ShenandoahMarkCompact::initialize();
306
307 ShenandoahCodeRoots::initialize();
308
309 return JNI_OK;
310 }
311
312 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
313 CollectedHeap(),
314 _shenandoah_policy(policy),
315 _concurrent_mark_in_progress(0),
316 _evacuation_in_progress(0),
317 _full_gc_in_progress(false),
318 _update_refs_in_progress(false),
319 _concurrent_partial_in_progress(false),
320 _free_regions(NULL),
321 _collection_set(NULL),
322 _bytes_allocated_since_cm(0),
323 _bytes_allocated_during_cm(0),
324 _allocated_last_gc(0),
325 _used_start_gc(0),
326 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
327 _ref_processor(NULL),
328 _top_at_mark_starts(NULL),
329 _top_at_mark_starts_base(NULL),
330 _mark_bit_map(),
331 _aux_bit_map(),
332 _connection_matrix(NULL),
333 _cancelled_concgc(0),
334 _need_update_refs(false),
335 _need_reset_bitmap(false),
336 _bitmap_valid(true),
337 _verifier(NULL),
338 _heap_lock(0),
339 _used_at_last_gc(0),
340 _alloc_seq_at_last_gc_start(0),
341 _alloc_seq_at_last_gc_end(0),
342 _safepoint_workers(NULL),
343 #ifdef ASSERT
344 _heap_lock_owner(NULL),
345 _heap_expansion_count(0),
346 #endif
347 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
348 _phase_timings(NULL),
349 _alloc_tracker(NULL)
350 {
351 log_info(gc, init)("Parallel GC threads: "UINT32_FORMAT, ParallelGCThreads);
352 log_info(gc, init)("Concurrent GC threads: "UINT32_FORMAT, ConcGCThreads);
353 log_info(gc, init)("Parallel reference processing enabled: %s", BOOL_TO_STR(ParallelRefProcEnabled));
354
355 _scm = new ShenandoahConcurrentMark();
356 _used = 0;
357
358 _max_workers = MAX2(_max_workers, 1U);
359 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
360 /* are_GC_task_threads */true,
361 /* are_ConcurrentGC_threads */false);
362 if (_workers == NULL) {
363 vm_exit_during_initialization("Failed necessary allocation.");
364 } else {
365 _workers->initialize_workers();
366 }
367
368 if (ParallelSafepointCleanupThreads > 1) {
369 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
370 ParallelSafepointCleanupThreads,
371 false, false);
372 _safepoint_workers->initialize_workers();
373 }
374 }
375
376 class ShenandoahResetBitmapTask : public AbstractGangTask {
377 private:
378 ShenandoahHeapRegionSet* _regions;
379
380 public:
381 ShenandoahResetBitmapTask(ShenandoahHeapRegionSet* regions) :
382 AbstractGangTask("Parallel Reset Bitmap Task"),
383 _regions(regions) {
384 _regions->clear_current_index();
385 }
386
387 void work(uint worker_id) {
388 ShenandoahHeapRegion* region = _regions->claim_next();
389 ShenandoahHeap* heap = ShenandoahHeap::heap();
390 while (region != NULL) {
391 if (region->is_committed()) {
392 HeapWord* bottom = region->bottom();
393 HeapWord* top = heap->top_at_mark_start(region->bottom());
394 if (top > bottom) {
395 heap->mark_bit_map()->clear_range_large(MemRegion(bottom, top));
396 }
397 assert(heap->is_bitmap_clear_range(bottom, region->end()), "must be clear");
398 heap->set_top_at_mark_start(region->bottom(), region->bottom());
399 }
400 region = _regions->claim_next();
401 }
402 }
403 };
404
405 void ShenandoahHeap::reset_mark_bitmap(WorkGang* workers) {
406 assert_gc_workers(workers->active_workers());
407
408 ShenandoahResetBitmapTask task = ShenandoahResetBitmapTask(_ordered_regions);
409 workers->run_task(&task);
410 }
411
412 bool ShenandoahHeap::is_bitmap_clear() {
413 for (size_t idx = 0; idx < _num_regions; idx++) {
414 ShenandoahHeapRegion* r = _ordered_regions->get(idx);
415 if (r->is_committed() && !is_bitmap_clear_range(r->bottom(), r->end())) {
416 return false;
417 }
418 }
419 return true;
420 }
421
422 bool ShenandoahHeap::is_bitmap_clear_range(HeapWord* start, HeapWord* end) {
423 return _mark_bit_map.getNextMarkedWordAddress(start, end) == end;
424 }
425
426 void ShenandoahHeap::print_on(outputStream* st) const {
427 st->print_cr("Shenandoah Heap");
428 st->print_cr(" " SIZE_FORMAT "K total, " SIZE_FORMAT "K committed, " SIZE_FORMAT "K used",
429 capacity() / K, committed() / K, used() / K);
430 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"K regions",
431 num_regions(), ShenandoahHeapRegion::region_size_bytes() / K);
432
433 st->print("Status: ");
434 if (concurrent_mark_in_progress()) {
435 st->print("marking ");
436 } else if (is_evacuation_in_progress()) {
437 st->print("evacuating ");
438 } else if (is_update_refs_in_progress()) {
439 st->print("updating refs ");
440 } else {
441 st->print("idle ");
442 }
443 if (cancelled_concgc()) {
444 st->print("cancelled ");
445 }
446 st->cr();
447
448 st->print_cr("Reserved region:");
449 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
450 p2i(reserved_region().start()),
451 p2i(reserved_region().end()));
452
453 if (UseShenandoahMatrix) {
454 st->print_cr("Matrix:");
455
456 ShenandoahConnectionMatrix* matrix = connection_matrix();
457 if (matrix != NULL) {
458 st->print_cr(" - base: " PTR_FORMAT, p2i(matrix->matrix_addr()));
459 st->print_cr(" - stride: " SIZE_FORMAT, matrix->stride());
460 st->print_cr(" - magic: " PTR_FORMAT, matrix->magic_offset());
461 } else {
462 st->print_cr(" No matrix.");
463 }
464 }
465
466 if (Verbose) {
467 print_heap_regions_on(st);
468 }
469 }
470
471 class ShenandoahInitGCLABClosure : public ThreadClosure {
472 public:
473 void do_thread(Thread* thread) {
474 thread->gclab().initialize(true);
475 }
476 };
477
478 void ShenandoahHeap::post_initialize() {
479 if (UseTLAB) {
480 MutexLocker ml(Threads_lock);
481
482 ShenandoahInitGCLABClosure init_gclabs;
483 Threads::java_threads_do(&init_gclabs);
484 gc_threads_do(&init_gclabs);
485
486 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
487 // Now, we will let WorkGang to initialize gclab when new worker is created.
488 _workers->set_initialize_gclab();
489 }
490
491 _scm->initialize(_max_workers);
492
493 ref_processing_init();
494
495 _shenandoah_policy->post_heap_initialize();
496 }
497
498 size_t ShenandoahHeap::used() const {
499 OrderAccess::acquire();
500 return _used;
501 }
502
503 size_t ShenandoahHeap::committed() const {
504 OrderAccess::acquire();
505 return _committed;
506 }
507
508 void ShenandoahHeap::increase_committed(size_t bytes) {
509 assert_heaplock_or_safepoint();
510 _committed += bytes;
511 }
512
513 void ShenandoahHeap::decrease_committed(size_t bytes) {
514 assert_heaplock_or_safepoint();
515 _committed -= bytes;
516 }
517
518 void ShenandoahHeap::increase_used(size_t bytes) {
519 assert_heaplock_or_safepoint();
520 _used += bytes;
521 }
522
523 void ShenandoahHeap::set_used(size_t bytes) {
524 assert_heaplock_or_safepoint();
525 _used = bytes;
526 }
527
528 void ShenandoahHeap::decrease_used(size_t bytes) {
529 assert_heaplock_or_safepoint();
530 assert(_used >= bytes, "never decrease heap size by more than we've left");
531 _used -= bytes;
532 }
533
534 size_t ShenandoahHeap::capacity() const {
535 return num_regions() * ShenandoahHeapRegion::region_size_bytes();
536 }
537
538 bool ShenandoahHeap::is_maximal_no_gc() const {
539 Unimplemented();
540 return true;
541 }
542
543 size_t ShenandoahHeap::max_capacity() const {
544 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
545 }
546
547 size_t ShenandoahHeap::initial_capacity() const {
548 return _initial_size;
549 }
550
551 bool ShenandoahHeap::is_in(const void* p) const {
552 HeapWord* heap_base = (HeapWord*) base();
553 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
554 return p >= heap_base && p < last_region_end;
555 }
556
557 bool ShenandoahHeap::is_scavengable(const void* p) {
558 return true;
559 }
560
561 void ShenandoahHeap::handle_heap_shrinkage() {
562 ShenandoahHeapLocker locker(lock());
563
564 ShenandoahHeapRegionSet* set = regions();
565
566 size_t count = 0;
567 double current = os::elapsedTime();
568 for (size_t i = 0; i < num_regions(); i++) {
569 ShenandoahHeapRegion* r = set->get(i);
570 if (r->is_empty_committed() &&
571 (current - r->empty_time()) * 1000 > ShenandoahUncommitDelay &&
572 r->make_empty_uncommitted()) {
573 count++;
574 }
575 }
576
577 if (count > 0) {
578 log_info(gc)("Uncommitted " SIZE_FORMAT "M. Heap: " SIZE_FORMAT "M reserved, " SIZE_FORMAT "M committed, " SIZE_FORMAT "M used",
579 count * ShenandoahHeapRegion::region_size_bytes() / M, capacity() / M, committed() / M, used() / M);
580 }
581 }
582
583 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
584 // Retain tlab and allocate object in shared space if
585 // the amount free in the tlab is too large to discard.
586 if (thread->gclab().free() > thread->gclab().refill_waste_limit()) {
587 thread->gclab().record_slow_allocation(size);
588 return NULL;
589 }
590
591 // Discard gclab and allocate a new one.
592 // To minimize fragmentation, the last GCLAB may be smaller than the rest.
593 size_t new_gclab_size = thread->gclab().compute_size(size);
594
595 thread->gclab().clear_before_allocation();
596
597 if (new_gclab_size == 0) {
598 return NULL;
599 }
600
601 // Allocate a new GCLAB...
602 HeapWord* obj = allocate_new_gclab(new_gclab_size);
603 if (obj == NULL) {
604 return NULL;
605 }
606
607 if (ZeroTLAB) {
608 // ..and clear it.
609 Copy::zero_to_words(obj, new_gclab_size);
610 } else {
611 // ...and zap just allocated object.
612 #ifdef ASSERT
613 // Skip mangling the space corresponding to the object header to
614 // ensure that the returned space is not considered parsable by
615 // any concurrent GC thread.
616 size_t hdr_size = oopDesc::header_size();
617 Copy::fill_to_words(obj + hdr_size, new_gclab_size - hdr_size, badHeapWordVal);
618 #endif // ASSERT
619 }
620 thread->gclab().fill(obj, obj + size, new_gclab_size);
621 return obj;
622 }
623
624 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t word_size) {
625 #ifdef ASSERT
626 log_debug(gc, alloc)("Allocate new tlab, requested size = " SIZE_FORMAT " bytes", word_size * HeapWordSize);
627 #endif
628 return allocate_new_lab(word_size, _alloc_tlab);
629 }
630
631 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t word_size) {
632 #ifdef ASSERT
633 log_debug(gc, alloc)("Allocate new gclab, requested size = " SIZE_FORMAT " bytes", word_size * HeapWordSize);
634 #endif
635 return allocate_new_lab(word_size, _alloc_gclab);
636 }
637
638 HeapWord* ShenandoahHeap::allocate_new_lab(size_t word_size, AllocType type) {
639 HeapWord* result = allocate_memory(word_size, type);
640
641 if (result != NULL) {
642 assert(! in_collection_set(result), "Never allocate in collection set");
643 _bytes_allocated_since_cm += word_size * HeapWordSize;
644
645 log_develop_trace(gc, tlab)("allocating new tlab of size "SIZE_FORMAT" at addr "PTR_FORMAT, word_size, p2i(result));
646
647 }
648 return result;
649 }
650
651 ShenandoahHeap* ShenandoahHeap::heap() {
652 CollectedHeap* heap = Universe::heap();
653 assert(heap != NULL, "Unitialized access to ShenandoahHeap::heap()");
654 assert(heap->kind() == CollectedHeap::ShenandoahHeap, "not a shenandoah heap");
655 return (ShenandoahHeap*) heap;
656 }
657
658 ShenandoahHeap* ShenandoahHeap::heap_no_check() {
659 CollectedHeap* heap = Universe::heap();
660 return (ShenandoahHeap*) heap;
661 }
662
663 HeapWord* ShenandoahHeap::allocate_memory(size_t word_size, AllocType type) {
664 ShenandoahAllocTrace trace_alloc(word_size, type);
665
666 bool in_new_region = false;
667 HeapWord* result = allocate_memory_under_lock(word_size, type, in_new_region);
668
669 if (type == _alloc_tlab || type == _alloc_shared) {
670 // Allocation failed, try full-GC, then retry allocation.
671 //
672 // It might happen that one of the threads requesting allocation would unblock
673 // way later after full-GC happened, only to fail the second allocation, because
674 // other threads have already depleted the free storage. In this case, a better
675 // strategy would be to try full-GC again.
676 //
677 // Lacking the way to detect progress from "collect" call, we are left with blindly
678 // retrying for some bounded number of times.
679 // TODO: Poll if Full GC made enough progress to warrant retry.
680 int tries = 0;
681 while ((result == NULL) && (tries++ < ShenandoahFullGCTries)) {
682 log_debug(gc)("[" PTR_FORMAT " Failed to allocate " SIZE_FORMAT " bytes, doing full GC, try %d",
683 p2i(Thread::current()), word_size * HeapWordSize, tries);
684 collect(GCCause::_allocation_failure);
685 result = allocate_memory_under_lock(word_size, type, in_new_region);
686 }
687 }
688
689 if (in_new_region) {
690 // Update monitoring counters when we took a new region. This amortizes the
691 // update costs on slow path.
692 concurrent_thread()->trigger_counters_update();
693 }
694
695 log_develop_trace(gc, alloc)("allocate memory chunk of size "SIZE_FORMAT" at addr "PTR_FORMAT " by thread %d ",
696 word_size, p2i(result), Thread::current()->osthread()->thread_id());
697
698 return result;
699 }
700
701 HeapWord* ShenandoahHeap::allocate_memory_under_lock(size_t word_size, AllocType type, bool& in_new_region) {
702 ShenandoahHeapLocker locker(lock());
703 return _free_regions->allocate(word_size, type, in_new_region);
704 }
705
706 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
707 bool* gc_overhead_limit_was_exceeded) {
708 HeapWord* filler = allocate_memory(size + BrooksPointer::word_size(), _alloc_shared);
709 HeapWord* result = filler + BrooksPointer::word_size();
710 if (filler != NULL) {
711 BrooksPointer::initialize(oop(result));
712 _bytes_allocated_since_cm += size * HeapWordSize;
713
714 assert(! in_collection_set(result), "never allocate in targetted region");
715 return result;
716 } else {
717 return NULL;
718 }
719 }
720
721 class ShenandoahEvacuateUpdateRootsClosure: public ExtendedOopClosure {
722 private:
723 ShenandoahHeap* _heap;
724 Thread* _thread;
725 public:
726 ShenandoahEvacuateUpdateRootsClosure() :
727 _heap(ShenandoahHeap::heap()), _thread(Thread::current()) {
728 }
729
730 private:
731 template <class T>
732 void do_oop_work(T* p) {
733 assert(_heap->is_evacuation_in_progress(), "Only do this when evacuation is in progress");
734
735 T o = oopDesc::load_heap_oop(p);
736 if (! oopDesc::is_null(o)) {
737 oop obj = oopDesc::decode_heap_oop_not_null(o);
738 if (_heap->in_collection_set(obj)) {
739 assert(_heap->is_marked(obj), "only evacuate marked objects %d %d",
740 _heap->is_marked(obj), _heap->is_marked(ShenandoahBarrierSet::resolve_oop_static_not_null(obj)));
741 oop resolved = ShenandoahBarrierSet::resolve_oop_static_not_null(obj);
742 if (oopDesc::unsafe_equals(resolved, obj)) {
743 bool evac;
744 resolved = _heap->evacuate_object(obj, _thread, evac);
745 }
746 oopDesc::encode_store_heap_oop(p, resolved);
747 }
748 }
749 }
750
751 public:
752 void do_oop(oop* p) {
753 do_oop_work(p);
754 }
755 void do_oop(narrowOop* p) {
756 do_oop_work(p);
757 }
758 };
759
760 class ShenandoahEvacuateRootsClosure: public ExtendedOopClosure {
761 private:
762 ShenandoahHeap* _heap;
763 Thread* _thread;
764 public:
765 ShenandoahEvacuateRootsClosure() :
766 _heap(ShenandoahHeap::heap()), _thread(Thread::current()) {
767 }
768
769 private:
770 template <class T>
771 void do_oop_work(T* p) {
772 T o = oopDesc::load_heap_oop(p);
773 if (! oopDesc::is_null(o)) {
774 oop obj = oopDesc::decode_heap_oop_not_null(o);
775 if (_heap->in_collection_set(obj)) {
776 oop resolved = ShenandoahBarrierSet::resolve_oop_static_not_null(obj);
777 if (oopDesc::unsafe_equals(resolved, obj)) {
778 bool evac;
779 _heap->evacuate_object(obj, _thread, evac);
780 }
781 }
782 }
783 }
784
785 public:
786 void do_oop(oop* p) {
787 do_oop_work(p);
788 }
789 void do_oop(narrowOop* p) {
790 do_oop_work(p);
791 }
792 };
793
794 class ShenandoahParallelEvacuateRegionObjectClosure : public ObjectClosure {
795 private:
796 ShenandoahHeap* const _heap;
797 Thread* const _thread;
798 public:
799 ShenandoahParallelEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
800 _heap(heap), _thread(Thread::current()) {}
801
802 void do_object(oop p) {
803 assert(_heap->is_marked(p), "expect only marked objects");
804 if (oopDesc::unsafe_equals(p, ShenandoahBarrierSet::resolve_oop_static_not_null(p))) {
805 bool evac;
806 _heap->evacuate_object(p, _thread, evac);
807 }
808 }
809 };
810
811 class ShenandoahParallelEvacuationTask : public AbstractGangTask {
812 private:
813 ShenandoahHeap* const _sh;
814 ShenandoahCollectionSet* const _cs;
815 volatile jbyte _claimed_codecache;
816
817 bool claim_codecache() {
818 jbyte old = Atomic::cmpxchg((jbyte)1, &_claimed_codecache, (jbyte)0);
819 return old == 0;
820 }
821 public:
822 ShenandoahParallelEvacuationTask(ShenandoahHeap* sh,
823 ShenandoahCollectionSet* cs) :
824 AbstractGangTask("Parallel Evacuation Task"),
825 _cs(cs),
826 _sh(sh),
827 _claimed_codecache(0)
828 {}
829
830 void work(uint worker_id) {
831
832 SuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
833
834 // If concurrent code cache evac is enabled, evacuate it here.
835 // Note we cannot update the roots here, because we risk non-atomic stores to the alive
836 // nmethods. The update would be handled elsewhere.
837 if (ShenandoahConcurrentEvacCodeRoots && claim_codecache()) {
838 ShenandoahEvacuateRootsClosure cl;
839 MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
840 CodeBlobToOopClosure blobs(&cl, !CodeBlobToOopClosure::FixRelocations);
841 CodeCache::blobs_do(&blobs);
842 }
843
844 ShenandoahParallelEvacuateRegionObjectClosure cl(_sh);
845 ShenandoahHeapRegion* r;
846 while ((r =_cs->claim_next()) != NULL) {
847 log_develop_trace(gc, region)("Thread "INT32_FORMAT" claimed Heap Region "SIZE_FORMAT,
848 worker_id,
849 r->region_number());
850
851 assert(r->has_live(), "all-garbage regions are reclaimed early");
852 _sh->marked_object_iterate(r, &cl);
853
854 if (_sh->check_cancelled_concgc_and_yield()) {
855 log_develop_trace(gc, region)("Cancelled concgc while evacuating region " SIZE_FORMAT, r->region_number());
856 break;
857 }
858 }
859 }
860 };
861
862 void ShenandoahHeap::trash_cset_regions() {
863 ShenandoahHeapLocker locker(lock());
864
865 ShenandoahCollectionSet* set = collection_set();
866 ShenandoahHeapRegion* r;
867 set->clear_current_index();
868 while ((r = set->next()) != NULL) {
869 r->make_trash();
870 }
871 collection_set()->clear();
872 }
873
874 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
875 st->print_cr("Heap Regions:");
876 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
877 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
878 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start (previous, next)");
879 st->print_cr("FTS=first use timestamp, LTS=last use timestamp");
880
881 _ordered_regions->print_on(st);
882 }
883
884 size_t ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
885 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
886
887 oop humongous_obj = oop(start->bottom() + BrooksPointer::word_size());
888 size_t size = humongous_obj->size() + BrooksPointer::word_size();
889 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
890 size_t index = start->region_number() + required_regions - 1;
891
892 assert(!start->has_live(), "liveness must be zero");
893 log_trace(gc, humongous)("Reclaiming "SIZE_FORMAT" humongous regions for object of size: "SIZE_FORMAT" words", required_regions, size);
894
895 for(size_t i = 0; i < required_regions; i++) {
896 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
897 // as it expects that every region belongs to a humongous region starting with a humongous start region.
898 ShenandoahHeapRegion* region = _ordered_regions->get(index --);
899
900 LogTarget(Trace, gc, humongous) lt;
901 if (lt.is_enabled()) {
902 ResourceMark rm;
903 LogStream ls(lt);
904 region->print_on(&ls);
905 }
906
907 assert(region->is_humongous(), "expect correct humongous start or continuation");
908 assert(!in_collection_set(region), "Humongous region should not be in collection set");
909
910 region->make_trash();
911 }
912 return required_regions;
913 }
914
915 #ifdef ASSERT
916 class ShenandoahCheckCollectionSetClosure: public ShenandoahHeapRegionClosure {
917 bool heap_region_do(ShenandoahHeapRegion* r) {
918 assert(! ShenandoahHeap::heap()->in_collection_set(r), "Should have been cleared by now");
919 return false;
920 }
921 };
922 #endif
923
924 void ShenandoahHeap::prepare_for_concurrent_evacuation() {
925 assert(_ordered_regions->get(0)->region_number() == 0, "FIXME CHF. FIXME CHF!");
926
927 log_develop_trace(gc)("Thread %d started prepare_for_concurrent_evacuation", Thread::current()->osthread()->thread_id());
928
929 if (!cancelled_concgc()) {
930 // Allocations might have happened before we STWed here, record peak:
931 shenandoahPolicy()->record_peak_occupancy();
932
933 make_tlabs_parsable(true);
934
935 if (ShenandoahVerify) {
936 verifier()->verify_after_concmark();
937 }
938
939 trash_cset_regions();
940
941 // NOTE: This needs to be done during a stop the world pause, because
942 // putting regions into the collection set concurrently with Java threads
943 // will create a race. In particular, acmp could fail because when we
944 // resolve the first operand, the containing region might not yet be in
945 // the collection set, and thus return the original oop. When the 2nd
946 // operand gets resolved, the region could be in the collection set
947 // and the oop gets evacuated. If both operands have originally been
948 // the same, we get false negatives.
949
950 {
951 ShenandoahHeapLocker locker(lock());
952 _collection_set->clear();
953 _free_regions->clear();
954
955 #ifdef ASSERT
956 ShenandoahCheckCollectionSetClosure ccsc;
957 _ordered_regions->heap_region_iterate(&ccsc);
958 #endif
959
960 _shenandoah_policy->choose_collection_set(_collection_set);
961
962 _shenandoah_policy->choose_free_set(_free_regions);
963 }
964
965 _bytes_allocated_since_cm = 0;
966
967 Universe::update_heap_info_at_gc();
968
969 if (ShenandoahVerify) {
970 verifier()->verify_before_evacuation();
971 }
972 }
973 }
974
975
976 class ShenandoahRetireTLABClosure : public ThreadClosure {
977 private:
978 bool _retire;
979
980 public:
981 ShenandoahRetireTLABClosure(bool retire) : _retire(retire) {}
982
983 void do_thread(Thread* thread) {
984 assert(thread->gclab().is_initialized(), "GCLAB should be initialized for %s", thread->name());
985 thread->gclab().make_parsable(_retire);
986 }
987 };
988
989 void ShenandoahHeap::make_tlabs_parsable(bool retire_tlabs) {
990 if (UseTLAB) {
991 CollectedHeap::ensure_parsability(retire_tlabs);
992 ShenandoahRetireTLABClosure cl(retire_tlabs);
993 Threads::java_threads_do(&cl);
994 gc_threads_do(&cl);
995 }
996 }
997
998
999 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1000 ShenandoahRootEvacuator* _rp;
1001 public:
1002
1003 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1004 AbstractGangTask("Shenandoah evacuate and update roots"),
1005 _rp(rp)
1006 {
1007 // Nothing else to do.
1008 }
1009
1010 void work(uint worker_id) {
1011 ShenandoahEvacuateUpdateRootsClosure cl;
1012
1013 if (ShenandoahConcurrentEvacCodeRoots) {
1014 _rp->process_evacuate_roots(&cl, NULL, worker_id);
1015 } else {
1016 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1017 _rp->process_evacuate_roots(&cl, &blobsCl, worker_id);
1018 }
1019 }
1020 };
1021
1022 class ShenandoahFixRootsTask : public AbstractGangTask {
1023 ShenandoahRootEvacuator* _rp;
1024 public:
1025
1026 ShenandoahFixRootsTask(ShenandoahRootEvacuator* rp) :
1027 AbstractGangTask("Shenandoah update roots"),
1028 _rp(rp)
1029 {
1030 // Nothing else to do.
1031 }
1032
1033 void work(uint worker_id) {
1034 ShenandoahUpdateRefsClosure cl;
1035 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1036
1037 _rp->process_evacuate_roots(&cl, &blobsCl, worker_id);
1038 }
1039 };
1040
1041 void ShenandoahHeap::evacuate_and_update_roots() {
1042
1043 #if defined(COMPILER2) || INCLUDE_JVMCI
1044 DerivedPointerTable::clear();
1045 #endif
1046 assert(SafepointSynchronize::is_at_safepoint(), "Only iterate roots while world is stopped");
1047
1048 {
1049 ShenandoahRootEvacuator rp(this, workers()->active_workers(), ShenandoahPhaseTimings::init_evac);
1050 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1051 workers()->run_task(&roots_task);
1052 }
1053
1054 #if defined(COMPILER2) || INCLUDE_JVMCI
1055 DerivedPointerTable::update_pointers();
1056 #endif
1057 if (cancelled_concgc()) {
1058 fixup_roots();
1059 }
1060 }
1061
1062
1063 void ShenandoahHeap::fixup_roots() {
1064 assert(cancelled_concgc(), "Only after concurrent cycle failed");
1065
1066 // If initial evacuation has been cancelled, we need to update all references
1067 // after all workers have finished. Otherwise we might run into the following problem:
1068 // GC thread 1 cannot allocate anymore, thus evacuation fails, leaves from-space ptr of object X.
1069 // GC thread 2 evacuates the same object X to to-space
1070 // which leaves a truly dangling from-space reference in the first root oop*. This must not happen.
1071 // clear() and update_pointers() must always be called in pairs,
1072 // cannot nest with above clear()/update_pointers().
1073 #if defined(COMPILER2) || INCLUDE_JVMCI
1074 DerivedPointerTable::clear();
1075 #endif
1076 ShenandoahRootEvacuator rp(this, workers()->active_workers(), ShenandoahPhaseTimings::init_evac);
1077 ShenandoahFixRootsTask update_roots_task(&rp);
1078 workers()->run_task(&update_roots_task);
1079 #if defined(COMPILER2) || INCLUDE_JVMCI
1080 DerivedPointerTable::update_pointers();
1081 #endif
1082 }
1083
1084 void ShenandoahHeap::do_evacuation() {
1085 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
1086
1087 LogTarget(Trace, gc, region) lt_region;
1088 LogTarget(Trace, gc, cset) lt_cset;
1089
1090 if (lt_region.is_enabled()) {
1091 ResourceMark rm;
1092 LogStream ls(lt_region);
1093 ls.print_cr("All available regions:");
1094 print_heap_regions_on(&ls);
1095 }
1096
1097 if (lt_cset.is_enabled()) {
1098 ResourceMark rm;
1099 LogStream ls(lt_cset);
1100 ls.print_cr("Collection set ("SIZE_FORMAT" regions):", _collection_set->count());
1101 _collection_set->print_on(&ls);
1102
1103 ls.print_cr("Free set:");
1104 _free_regions->print_on(&ls);
1105 }
1106
1107 ShenandoahParallelEvacuationTask task(this, _collection_set);
1108 workers()->run_task(&task);
1109
1110 if (lt_cset.is_enabled()) {
1111 ResourceMark rm;
1112 LogStream ls(lt_cset);
1113 ls.print_cr("After evacuation collection set ("SIZE_FORMAT" regions):",
1114 _collection_set->count());
1115 _collection_set->print_on(&ls);
1116
1117 ls.print_cr("After evacuation free set:");
1118 _free_regions->print_on(&ls);
1119 }
1120
1121 if (lt_region.is_enabled()) {
1122 ResourceMark rm;
1123 LogStream ls(lt_region);
1124 ls.print_cr("All regions after evacuation:");
1125 print_heap_regions_on(&ls);
1126 }
1127 }
1128
1129 void ShenandoahHeap::roots_iterate(OopClosure* cl) {
1130 assert(SafepointSynchronize::is_at_safepoint(), "Only iterate roots while world is stopped");
1131
1132 CodeBlobToOopClosure blobsCl(cl, false);
1133 CLDToOopClosure cldCl(cl);
1134
1135 ShenandoahRootProcessor rp(this, 1, ShenandoahPhaseTimings::_num_phases);
1136 rp.process_all_roots(cl, NULL, &cldCl, &blobsCl, 0);
1137 }
1138
1139 bool ShenandoahHeap::supports_tlab_allocation() const {
1140 return true;
1141 }
1142
1143 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1144 return MIN2(_free_regions->unsafe_peek_free(), max_tlab_size());
1145 }
1146
1147 size_t ShenandoahHeap::max_tlab_size() const {
1148 return ShenandoahHeapRegion::max_tlab_size_bytes();
1149 }
1150
1151 class ShenandoahResizeGCLABClosure : public ThreadClosure {
1152 public:
1153 void do_thread(Thread* thread) {
1154 assert(thread->gclab().is_initialized(), "GCLAB should be initialized for %s", thread->name());
1155 thread->gclab().resize();
1156 }
1157 };
1158
1159 void ShenandoahHeap::resize_all_tlabs() {
1160 CollectedHeap::resize_all_tlabs();
1161
1162 ShenandoahResizeGCLABClosure cl;
1163 Threads::java_threads_do(&cl);
1164 gc_threads_do(&cl);
1165 }
1166
1167 class ShenandoahAccumulateStatisticsGCLABClosure : public ThreadClosure {
1168 public:
1169 void do_thread(Thread* thread) {
1170 assert(thread->gclab().is_initialized(), "GCLAB should be initialized for %s", thread->name());
1171 thread->gclab().accumulate_statistics();
1172 thread->gclab().initialize_statistics();
1173 }
1174 };
1175
1176 void ShenandoahHeap::accumulate_statistics_all_gclabs() {
1177 ShenandoahAccumulateStatisticsGCLABClosure cl;
1178 Threads::java_threads_do(&cl);
1179 gc_threads_do(&cl);
1180 }
1181
1182 bool ShenandoahHeap::can_elide_tlab_store_barriers() const {
1183 return true;
1184 }
1185
1186 oop ShenandoahHeap::new_store_pre_barrier(JavaThread* thread, oop new_obj) {
1187 // Overridden to do nothing.
1188 return new_obj;
1189 }
1190
1191 bool ShenandoahHeap::can_elide_initializing_store_barrier(oop new_obj) {
1192 return true;
1193 }
1194
1195 bool ShenandoahHeap::card_mark_must_follow_store() const {
1196 return false;
1197 }
1198
1199 void ShenandoahHeap::collect(GCCause::Cause cause) {
1200 assert(cause != GCCause::_gc_locker, "no JNI critical callback");
1201 if (GCCause::is_user_requested_gc(cause)) {
1202 if (!DisableExplicitGC) {
1203 if (ExplicitGCInvokesConcurrent) {
1204 _concurrent_gc_thread->do_conc_gc();
1205 } else {
1206 _concurrent_gc_thread->do_full_gc(cause);
1207 }
1208 }
1209 } else if (cause == GCCause::_allocation_failure) {
1210 collector_policy()->set_should_clear_all_soft_refs(true);
1211 _concurrent_gc_thread->do_full_gc(cause);
1212 }
1213 }
1214
1215 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1216 //assert(false, "Shouldn't need to do full collections");
1217 }
1218
1219 AdaptiveSizePolicy* ShenandoahHeap::size_policy() {
1220 Unimplemented();
1221 return NULL;
1222
1223 }
1224
1225 CollectorPolicy* ShenandoahHeap::collector_policy() const {
1226 return _shenandoah_policy;
1227 }
1228
1229
1230 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1231 Space* sp = heap_region_containing(addr);
1232 if (sp != NULL) {
1233 return sp->block_start(addr);
1234 }
1235 return NULL;
1236 }
1237
1238 size_t ShenandoahHeap::block_size(const HeapWord* addr) const {
1239 Space* sp = heap_region_containing(addr);
1240 assert(sp != NULL, "block_size of address outside of heap");
1241 return sp->block_size(addr);
1242 }
1243
1244 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1245 Space* sp = heap_region_containing(addr);
1246 return sp->block_is_obj(addr);
1247 }
1248
1249 jlong ShenandoahHeap::millis_since_last_gc() {
1250 return 0;
1251 }
1252
1253 void ShenandoahHeap::prepare_for_verify() {
1254 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1255 make_tlabs_parsable(false);
1256 }
1257 }
1258
1259 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1260 workers()->print_worker_threads_on(st);
1261 }
1262
1263 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1264 workers()->threads_do(tcl);
1265 }
1266
1267 void ShenandoahHeap::print_tracing_info() const {
1268 LogTarget(Info, gc, stats) lt;
1269 if (lt.is_enabled()) {
1270 ResourceMark rm;
1271 LogStream ls(lt);
1272
1273 phase_timings()->print_on(&ls);
1274
1275 ls.cr();
1276 ls.cr();
1277
1278 shenandoahPolicy()->print_gc_stats(&ls);
1279
1280 ls.cr();
1281 ls.cr();
1282
1283 if (ShenandoahAllocationTrace) {
1284 assert(alloc_tracker() != NULL, "Must be");
1285 alloc_tracker()->print_on(&ls);
1286 } else {
1287 ls.print_cr(" Allocation tracing is disabled, use -XX:+ShenandoahAllocationTrace to enable.");
1288 }
1289 }
1290 }
1291
1292 void ShenandoahHeap::verify(VerifyOption vo) {
1293 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1294 if (ShenandoahVerify) {
1295 verifier()->verify_generic(vo);
1296 } else {
1297 // TODO: Consider allocating verification bitmaps on demand,
1298 // and turn this on unconditionally.
1299 }
1300 }
1301 }
1302 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1303 return _free_regions->capacity();
1304 }
1305
1306 class ShenandoahIterateObjectClosureRegionClosure: public ShenandoahHeapRegionClosure {
1307 ObjectClosure* _cl;
1308 public:
1309 ShenandoahIterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1310 bool heap_region_do(ShenandoahHeapRegion* r) {
1311 ShenandoahHeap::heap()->marked_object_iterate(r, _cl);
1312 return false;
1313 }
1314 };
1315
1316 class ObjectIterateScanRootClosure : public ExtendedOopClosure {
1317 private:
1318 MarkBitMap* _bitmap;
1319 Stack<oop,mtGC>* _oop_stack;
1320
1321 template <class T>
1322 void do_oop_work(T* p) {
1323 T o = oopDesc::load_heap_oop(p);
1324 if (!oopDesc::is_null(o)) {
1325 oop obj = oopDesc::decode_heap_oop_not_null(o);
1326 obj = ShenandoahBarrierSet::resolve_oop_static_not_null(obj);
1327 assert(oopDesc::is_oop(obj), "must be a valid oop");
1328 if (!_bitmap->isMarked((HeapWord*) obj)) {
1329 _bitmap->mark((HeapWord*) obj);
1330 _oop_stack->push(obj);
1331 }
1332 }
1333 }
1334
1335 public:
1336 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1337 _bitmap(bitmap), _oop_stack(oop_stack) {}
1338 void do_oop(oop* p) { do_oop_work(p); }
1339 void do_oop(narrowOop* p) { do_oop_work(p); }
1340 };
1341
1342 /*
1343 * This is public API, used in preparation of object_iterate().
1344 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1345 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1346 * control, we call SH::make_tlabs_parsable().
1347 */
1348 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1349 // No-op.
1350 }
1351
1352
1353 /*
1354 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1355 *
1356 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1357 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1358 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1359 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1360 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1361 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1362 * wiped the bitmap in preparation for next marking).
1363 *
1364 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1365 * objects as we mark+traverse through the heap, starting from GC roots. This is ok. JVMTI
1366 * IterateThroughHeap is allowed to report dead objects, but is not required to do so.
1367 */
1368 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1369 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1370 if (!os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1371 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1372 return;
1373 }
1374
1375 Stack<oop,mtGC> oop_stack;
1376
1377 // First, we process all GC roots. This populates the work stack with initial objects.
1378 ShenandoahRootProcessor rp(this, 1, ShenandoahPhaseTimings::_num_phases);
1379 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1380 CLDToOopClosure clds(&oops, false);
1381 CodeBlobToOopClosure blobs(&oops, false);
1382 rp.process_all_roots(&oops, &oops, &clds, &blobs, 0);
1383
1384 // Work through the oop stack to traverse heap.
1385 while (! oop_stack.is_empty()) {
1386 oop obj = oop_stack.pop();
1387 assert(oopDesc::is_oop(obj), "must be a valid oop");
1388 cl->do_object(obj);
1389 obj->oop_iterate(&oops);
1390 }
1391
1392 assert(oop_stack.is_empty(), "should be empty");
1393
1394 if (!os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1395 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1396 }
1397 }
1398
1399 void ShenandoahHeap::safe_object_iterate(ObjectClosure* cl) {
1400 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1401 object_iterate(cl);
1402 }
1403
1404 // Apply blk->heap_region_do() on all committed regions in address order,
1405 // terminating the iteration early if heap_region_do() returns true.
1406 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk, bool skip_cset_regions, bool skip_humongous_continuation) const {
1407 for (size_t i = 0; i < num_regions(); i++) {
1408 ShenandoahHeapRegion* current = _ordered_regions->get(i);
1409 if (skip_humongous_continuation && current->is_humongous_continuation()) {
1410 continue;
1411 }
1412 if (skip_cset_regions && in_collection_set(current)) {
1413 continue;
1414 }
1415 if (blk->heap_region_do(current)) {
1416 return;
1417 }
1418 }
1419 }
1420
1421 class ShenandoahClearLivenessClosure : public ShenandoahHeapRegionClosure {
1422 private:
1423 ShenandoahHeap* sh;
1424 public:
1425 ShenandoahClearLivenessClosure(ShenandoahHeap* heap) : sh(heap) {}
1426
1427 bool heap_region_do(ShenandoahHeapRegion* r) {
1428 r->clear_live_data();
1429 sh->set_top_at_mark_start(r->bottom(), r->top());
1430 return false;
1431 }
1432 };
1433
1434 void ShenandoahHeap::start_concurrent_marking() {
1435 if (ShenandoahVerify) {
1436 verifier()->verify_before_concmark();
1437 }
1438
1439 {
1440 ShenandoahGCPhase phase(ShenandoahPhaseTimings::accumulate_stats);
1441 accumulate_statistics_all_tlabs();
1442 }
1443
1444 set_concurrent_mark_in_progress(true);
1445 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1446 if (UseTLAB) {
1447 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1448 make_tlabs_parsable(true);
1449 }
1450
1451 _shenandoah_policy->record_bytes_allocated(_bytes_allocated_since_cm);
1452 _used_start_gc = used();
1453
1454 {
1455 ShenandoahGCPhase phase(ShenandoahPhaseTimings::clear_liveness);
1456 ShenandoahClearLivenessClosure clc(this);
1457 heap_region_iterate(&clc);
1458 }
1459
1460 // Make above changes visible to worker threads
1461 OrderAccess::fence();
1462
1463 concurrentMark()->init_mark_roots();
1464
1465 if (UseTLAB) {
1466 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1467 resize_all_tlabs();
1468 }
1469 }
1470
1471 void ShenandoahHeap::stop_concurrent_marking() {
1472 assert(concurrent_mark_in_progress(), "How else could we get here?");
1473 if (! cancelled_concgc()) {
1474 // If we needed to update refs, and concurrent marking has been cancelled,
1475 // we need to finish updating references.
1476 set_need_update_refs(false);
1477 }
1478 set_concurrent_mark_in_progress(false);
1479
1480 LogTarget(Trace, gc, region) lt;
1481 if (lt.is_enabled()) {
1482 ResourceMark rm;
1483 LogStream ls(lt);
1484 ls.print_cr("Regions at stopping the concurrent mark:");
1485 print_heap_regions_on(&ls);
1486 }
1487 }
1488
1489 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1490 _concurrent_mark_in_progress = in_progress ? 1 : 0;
1491 JavaThread::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1492 }
1493
1494 void ShenandoahHeap::set_concurrent_partial_in_progress(bool in_progress) {
1495 _concurrent_partial_in_progress = in_progress;
1496 JavaThread::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1497 set_evacuation_in_progress_at_safepoint(in_progress);
1498 }
1499
1500 void ShenandoahHeap::set_evacuation_in_progress_concurrently(bool in_progress) {
1501 // Note: it is important to first release the _evacuation_in_progress flag here,
1502 // so that Java threads can get out of oom_during_evacuation() and reach a safepoint,
1503 // in case a VM task is pending.
1504 set_evacuation_in_progress(in_progress);
1505 MutexLocker mu(Threads_lock);
1506 JavaThread::set_evacuation_in_progress_all_threads(in_progress);
1507 }
1508
1509 void ShenandoahHeap::set_evacuation_in_progress_at_safepoint(bool in_progress) {
1510 assert(SafepointSynchronize::is_at_safepoint(), "Only call this at safepoint");
1511 set_evacuation_in_progress(in_progress);
1512 JavaThread::set_evacuation_in_progress_all_threads(in_progress);
1513 }
1514
1515 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1516 _evacuation_in_progress = in_progress ? 1 : 0;
1517 OrderAccess::fence();
1518 }
1519
1520 void ShenandoahHeap::oom_during_evacuation() {
1521 log_develop_trace(gc)("Out of memory during evacuation, cancel evacuation, schedule full GC by thread %d",
1522 Thread::current()->osthread()->thread_id());
1523
1524 // We ran out of memory during evacuation. Cancel evacuation, and schedule a full-GC.
1525 collector_policy()->set_should_clear_all_soft_refs(true);
1526 concurrent_thread()->try_set_full_gc();
1527 cancel_concgc(_oom_evacuation);
1528
1529 if ((! Thread::current()->is_GC_task_thread()) && (! Thread::current()->is_ConcurrentGC_thread())) {
1530 assert(! Threads_lock->owned_by_self()
1531 || SafepointSynchronize::is_at_safepoint(), "must not hold Threads_lock here");
1532 log_warning(gc)("OOM during evacuation. Let Java thread wait until evacuation finishes.");
1533 while (_evacuation_in_progress) { // wait.
1534 Thread::current()->_ParkEvent->park(1);
1535 }
1536 }
1537
1538 }
1539
1540 HeapWord* ShenandoahHeap::tlab_post_allocation_setup(HeapWord* obj) {
1541 // Initialize Brooks pointer for the next object
1542 HeapWord* result = obj + BrooksPointer::word_size();
1543 BrooksPointer::initialize(oop(result));
1544 return result;
1545 }
1546
1547 uint ShenandoahHeap::oop_extra_words() {
1548 return BrooksPointer::word_size();
1549 }
1550
1551 ShenandoahForwardedIsAliveClosure::ShenandoahForwardedIsAliveClosure() :
1552 _heap(ShenandoahHeap::heap_no_check()) {
1553 }
1554
1555 bool ShenandoahForwardedIsAliveClosure::do_object_b(oop obj) {
1556 assert(_heap != NULL, "sanity");
1557 obj = ShenandoahBarrierSet::resolve_oop_static_not_null(obj);
1558 #ifdef ASSERT
1559 if (_heap->concurrent_mark_in_progress()) {
1560 assert(oopDesc::unsafe_equals(obj, ShenandoahBarrierSet::resolve_oop_static_not_null(obj)), "only query to-space");
1561 }
1562 #endif
1563 assert(!oopDesc::is_null(obj), "null");
1564 return _heap->is_marked(obj);
1565 }
1566
1567 ShenandoahIsAliveClosure::ShenandoahIsAliveClosure() :
1568 _heap(ShenandoahHeap::heap_no_check()) {
1569 }
1570
1571 bool ShenandoahIsAliveClosure::do_object_b(oop obj) {
1572 assert(_heap != NULL, "sanity");
1573 assert(!oopDesc::is_null(obj), "null");
1574 assert(oopDesc::unsafe_equals(obj, ShenandoahBarrierSet::resolve_oop_static_not_null(obj)), "only query to-space");
1575 return _heap->is_marked(obj);
1576 }
1577
1578 BoolObjectClosure* ShenandoahHeap::is_alive_closure() {
1579 return need_update_refs() ?
1580 (BoolObjectClosure*) &_forwarded_is_alive :
1581 (BoolObjectClosure*) &_is_alive;
1582 }
1583
1584 void ShenandoahHeap::ref_processing_init() {
1585 MemRegion mr = reserved_region();
1586
1587 _forwarded_is_alive.init(ShenandoahHeap::heap());
1588 _is_alive.init(ShenandoahHeap::heap());
1589 assert(_max_workers > 0, "Sanity");
1590
1591 _ref_processor =
1592 new ReferenceProcessor(mr, // span
1593 ParallelRefProcEnabled, // MT processing
1594 _max_workers, // Degree of MT processing
1595 true, // MT discovery
1596 _max_workers, // Degree of MT discovery
1597 false, // Reference discovery is not atomic
1598 &_forwarded_is_alive); // Pessimistically assume "forwarded"
1599 }
1600
1601
1602 GCTracer* ShenandoahHeap::tracer() {
1603 return shenandoahPolicy()->tracer();
1604 }
1605
1606 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1607 return _free_regions->used();
1608 }
1609
1610 void ShenandoahHeap::cancel_concgc(GCCause::Cause cause) {
1611 if (try_cancel_concgc()) {
1612 log_info(gc)("Cancelling concurrent GC: %s", GCCause::to_string(cause));
1613 _shenandoah_policy->report_concgc_cancelled();
1614 }
1615 }
1616
1617 void ShenandoahHeap::cancel_concgc(ShenandoahCancelCause cause) {
1618 if (try_cancel_concgc()) {
1619 log_info(gc)("Cancelling concurrent GC: %s", cancel_cause_to_string(cause));
1620 _shenandoah_policy->report_concgc_cancelled();
1621 }
1622 }
1623
1624 const char* ShenandoahHeap::cancel_cause_to_string(ShenandoahCancelCause cause) {
1625 switch (cause) {
1626 case _oom_evacuation:
1627 return "Out of memory for evacuation";
1628 case _vm_stop:
1629 return "Stopping VM";
1630 default:
1631 return "Unknown";
1632 }
1633 }
1634
1635 uint ShenandoahHeap::max_workers() {
1636 return _max_workers;
1637 }
1638
1639 void ShenandoahHeap::stop() {
1640 // The shutdown sequence should be able to terminate when GC is running.
1641
1642 // Step 0. Notify policy to disable event recording.
1643 _shenandoah_policy->record_shutdown();
1644
1645 // Step 1. Notify control thread that we are in shutdown.
1646 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1647 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1648 _concurrent_gc_thread->prepare_for_graceful_shutdown();
1649
1650 // Step 2. Notify GC workers that we are cancelling GC.
1651 cancel_concgc(_vm_stop);
1652
1653 // Step 3. Wait until GC worker exits normally.
1654 _concurrent_gc_thread->stop();
1655 }
1656
1657 void ShenandoahHeap::unload_classes_and_cleanup_tables(bool full_gc) {
1658 ShenandoahPhaseTimings::Phase phase_root =
1659 full_gc ?
1660 ShenandoahPhaseTimings::full_gc_purge :
1661 ShenandoahPhaseTimings::purge;
1662
1663 ShenandoahPhaseTimings::Phase phase_unload =
1664 full_gc ?
1665 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1666 ShenandoahPhaseTimings::purge_class_unload;
1667
1668 ShenandoahPhaseTimings::Phase phase_cldg =
1669 full_gc ?
1670 ShenandoahPhaseTimings::full_gc_purge_cldg :
1671 ShenandoahPhaseTimings::purge_cldg;
1672
1673 ShenandoahPhaseTimings::Phase phase_par =
1674 full_gc ?
1675 ShenandoahPhaseTimings::full_gc_purge_par :
1676 ShenandoahPhaseTimings::purge_par;
1677
1678 ShenandoahPhaseTimings::Phase phase_par_classes =
1679 full_gc ?
1680 ShenandoahPhaseTimings::full_gc_purge_par_classes :
1681 ShenandoahPhaseTimings::purge_par_classes;
1682
1683 ShenandoahPhaseTimings::Phase phase_par_codecache =
1684 full_gc ?
1685 ShenandoahPhaseTimings::full_gc_purge_par_codecache :
1686 ShenandoahPhaseTimings::purge_par_codecache;
1687
1688 ShenandoahPhaseTimings::Phase phase_par_rmt =
1689 full_gc ?
1690 ShenandoahPhaseTimings::full_gc_purge_par_rmt :
1691 ShenandoahPhaseTimings::purge_par_rmt;
1692
1693 ShenandoahPhaseTimings::Phase phase_par_symbstring =
1694 full_gc ?
1695 ShenandoahPhaseTimings::full_gc_purge_par_symbstring :
1696 ShenandoahPhaseTimings::purge_par_symbstring;
1697
1698 ShenandoahPhaseTimings::Phase phase_par_sync =
1699 full_gc ?
1700 ShenandoahPhaseTimings::full_gc_purge_par_sync :
1701 ShenandoahPhaseTimings::purge_par_sync;
1702
1703 ShenandoahGCPhase root_phase(phase_root);
1704
1705 BoolObjectClosure* is_alive = is_alive_closure();
1706
1707 bool purged_class;
1708
1709 // Unload classes and purge SystemDictionary.
1710 {
1711 ShenandoahGCPhase phase(phase_unload);
1712 purged_class = SystemDictionary::do_unloading(is_alive,
1713 full_gc ? ShenandoahMarkCompact::gc_timer() : gc_timer(),
1714 true);
1715 }
1716
1717 {
1718 ShenandoahGCPhase phase(phase_par);
1719 uint active = _workers->active_workers();
1720 ParallelCleaningTask unlink_task(is_alive, true, true, active, purged_class);
1721 _workers->run_task(&unlink_task);
1722
1723 ShenandoahPhaseTimings* p = ShenandoahHeap::heap()->phase_timings();
1724 ParallelCleaningTimes times = unlink_task.times();
1725
1726 // "times" report total time, phase_tables_cc reports wall time. Divide total times
1727 // by active workers to get average time per worker, that would add up to wall time.
1728 p->record_phase_time(phase_par_classes, times.klass_work_us() / active);
1729 p->record_phase_time(phase_par_codecache, times.codecache_work_us() / active);
1730 p->record_phase_time(phase_par_rmt, times.rmt_work_us() / active);
1731 p->record_phase_time(phase_par_symbstring, times.tables_work_us() / active);
1732 p->record_phase_time(phase_par_sync, times.sync_us() / active);
1733 }
1734
1735 {
1736 ShenandoahGCPhase phase(phase_cldg);
1737 ClassLoaderDataGraph::purge();
1738 }
1739 }
1740
1741 void ShenandoahHeap::set_need_update_refs(bool need_update_refs) {
1742 _need_update_refs = need_update_refs;
1743 }
1744
1745 //fixme this should be in heapregionset
1746 ShenandoahHeapRegion* ShenandoahHeap::next_compaction_region(const ShenandoahHeapRegion* r) {
1747 size_t region_idx = r->region_number() + 1;
1748 ShenandoahHeapRegion* next = _ordered_regions->get(region_idx);
1749 guarantee(next->region_number() == region_idx, "region number must match");
1750 while (next->is_humongous()) {
1751 region_idx = next->region_number() + 1;
1752 next = _ordered_regions->get(region_idx);
1753 guarantee(next->region_number() == region_idx, "region number must match");
1754 }
1755 return next;
1756 }
1757
1758 ShenandoahMonitoringSupport* ShenandoahHeap::monitoring_support() {
1759 return _monitoring_support;
1760 }
1761
1762 MarkBitMap* ShenandoahHeap::mark_bit_map() {
1763 return &_mark_bit_map;
1764 }
1765
1766 void ShenandoahHeap::add_free_region(ShenandoahHeapRegion* r) {
1767 _free_regions->add_region(r);
1768 }
1769
1770 void ShenandoahHeap::clear_free_regions() {
1771 _free_regions->clear();
1772 }
1773
1774 address ShenandoahHeap::in_cset_fast_test_addr() {
1775 ShenandoahHeap* heap = ShenandoahHeap::heap();
1776 assert(heap->collection_set() != NULL, "Sanity");
1777 return (address) heap->collection_set()->biased_map_address();
1778 }
1779
1780 address ShenandoahHeap::cancelled_concgc_addr() {
1781 return (address) &(ShenandoahHeap::heap()->_cancelled_concgc);
1782 }
1783
1784
1785 size_t ShenandoahHeap::conservative_max_heap_alignment() {
1786 return ShenandoahMaxRegionSize;
1787 }
1788
1789 size_t ShenandoahHeap::bytes_allocated_since_cm() {
1790 return _bytes_allocated_since_cm;
1791 }
1792
1793 void ShenandoahHeap::set_bytes_allocated_since_cm(size_t bytes) {
1794 _bytes_allocated_since_cm = bytes;
1795 }
1796
1797 void ShenandoahHeap::set_top_at_mark_start(HeapWord* region_base, HeapWord* addr) {
1798 uintx index = ((uintx) region_base) >> ShenandoahHeapRegion::region_size_bytes_shift();
1799 _top_at_mark_starts[index] = addr;
1800 }
1801
1802 HeapWord* ShenandoahHeap::top_at_mark_start(HeapWord* region_base) {
1803 uintx index = ((uintx) region_base) >> ShenandoahHeapRegion::region_size_bytes_shift();
1804 return _top_at_mark_starts[index];
1805 }
1806
1807 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
1808 _full_gc_in_progress = in_progress;
1809 }
1810
1811 bool ShenandoahHeap::is_full_gc_in_progress() const {
1812 return _full_gc_in_progress;
1813 }
1814
1815 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
1816 _update_refs_in_progress = in_progress;
1817 }
1818
1819 bool ShenandoahHeap::is_update_refs_in_progress() const {
1820 return _update_refs_in_progress;
1821 }
1822
1823 void ShenandoahHeap::register_nmethod(nmethod* nm) {
1824 ShenandoahCodeRoots::add_nmethod(nm);
1825 }
1826
1827 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
1828 ShenandoahCodeRoots::remove_nmethod(nm);
1829 }
1830
1831 void ShenandoahHeap::pin_object(oop o) {
1832 ShenandoahHeapLocker locker(lock());
1833 heap_region_containing(o)->make_pinned();
1834 }
1835
1836 void ShenandoahHeap::unpin_object(oop o) {
1837 ShenandoahHeapLocker locker(lock());
1838 heap_region_containing(o)->make_unpinned();
1839 }
1840
1841 GCTimer* ShenandoahHeap::gc_timer() const {
1842 return _gc_timer;
1843 }
1844
1845 #ifdef ASSERT
1846 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
1847 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
1848
1849 if (SafepointSynchronize::is_at_safepoint()) {
1850 if (UseDynamicNumberOfGCThreads ||
1851 (FLAG_IS_DEFAULT(ParallelGCThreads) && ForceDynamicNumberOfGCThreads)) {
1852 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
1853 } else {
1854 // Use ParallelGCThreads inside safepoints
1855 assert(nworkers == ParallelGCThreads, "Use ParalleGCThreads within safepoints");
1856 }
1857 } else {
1858 if (UseDynamicNumberOfGCThreads ||
1859 (FLAG_IS_DEFAULT(ConcGCThreads) && ForceDynamicNumberOfGCThreads)) {
1860 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
1861 } else {
1862 // Use ConcGCThreads outside safepoints
1863 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
1864 }
1865 }
1866 }
1867 #endif
1868
1869 class ShenandoahCountGarbageClosure : public ShenandoahHeapRegionClosure {
1870 private:
1871 size_t _garbage;
1872 public:
1873 ShenandoahCountGarbageClosure() : _garbage(0) {
1874 }
1875
1876 bool heap_region_do(ShenandoahHeapRegion* r) {
1877 if (r->is_regular()) {
1878 _garbage += r->garbage();
1879 }
1880 return false;
1881 }
1882
1883 size_t garbage() {
1884 return _garbage;
1885 }
1886 };
1887
1888 size_t ShenandoahHeap::garbage() {
1889 ShenandoahCountGarbageClosure cl;
1890 heap_region_iterate(&cl);
1891 return cl.garbage();
1892 }
1893
1894 ShenandoahConnectionMatrix* ShenandoahHeap::connection_matrix() const {
1895 return _connection_matrix;
1896 }
1897
1898 ShenandoahPartialGC* ShenandoahHeap::partial_gc() {
1899 return _partial_gc;
1900 }
1901
1902 ShenandoahVerifier* ShenandoahHeap::verifier() {
1903 guarantee(ShenandoahVerify, "Should be enabled");
1904 assert (_verifier != NULL, "sanity");
1905 return _verifier;
1906 }
1907
1908 template<class T>
1909 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
1910 private:
1911 T cl;
1912 ShenandoahHeap* _heap;
1913 ShenandoahHeapRegionSet* _regions;
1914 bool _concurrent;
1915 public:
1916 ShenandoahUpdateHeapRefsTask(ShenandoahHeapRegionSet* regions, bool concurrent) :
1917 AbstractGangTask("Concurrent Update References Task"),
1918 cl(T()),
1919 _heap(ShenandoahHeap::heap()),
1920 _regions(regions),
1921 _concurrent(concurrent) {
1922 }
1923
1924 void work(uint worker_id) {
1925 SuspendibleThreadSetJoiner stsj(_concurrent && ShenandoahSuspendibleWorkers);
1926 ShenandoahHeapRegion* r = _regions->claim_next();
1927 while (r != NULL) {
1928 if (_heap->in_collection_set(r)) {
1929 HeapWord* bottom = r->bottom();
1930 HeapWord* top = _heap->top_at_mark_start(r->bottom());
1931 if (top > bottom) {
1932 _heap->mark_bit_map()->clear_range_large(MemRegion(bottom, top));
1933 }
1934 } else {
1935 if (r->is_active()) {
1936 _heap->marked_object_oop_safe_iterate(r, &cl);
1937 }
1938 }
1939 if (_heap->check_cancelled_concgc_and_yield(_concurrent)) {
1940 return;
1941 }
1942 r = _regions->claim_next();
1943 }
1944 }
1945 };
1946
1947 void ShenandoahHeap::update_heap_references(ShenandoahHeapRegionSet* update_regions, bool concurrent) {
1948 if (UseShenandoahMatrix) {
1949 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsMatrixClosure> task(update_regions, concurrent);
1950 workers()->run_task(&task);
1951 } else {
1952 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(update_regions, concurrent);
1953 workers()->run_task(&task);
1954 }
1955 }
1956
1957 void ShenandoahHeap::concurrent_update_heap_references() {
1958 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
1959 ShenandoahHeapRegionSet* update_regions = regions();
1960 update_regions->clear_current_index();
1961 update_heap_references(update_regions, true);
1962 }
1963
1964 void ShenandoahHeap::prepare_update_refs() {
1965 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
1966
1967 if (ShenandoahVerify) {
1968 verifier()->verify_before_updaterefs();
1969 }
1970
1971 set_evacuation_in_progress_at_safepoint(false);
1972 set_update_refs_in_progress(true);
1973 make_tlabs_parsable(true);
1974 if (UseShenandoahMatrix) {
1975 connection_matrix()->clear_all();
1976 }
1977 for (uint i = 0; i < num_regions(); i++) {
1978 ShenandoahHeapRegion* r = _ordered_regions->get(i);
1979 r->set_concurrent_iteration_safe_limit(r->top());
1980 }
1981 }
1982
1983 void ShenandoahHeap::finish_update_refs() {
1984 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
1985
1986 if (cancelled_concgc()) {
1987 ShenandoahGCPhase final_work(ShenandoahPhaseTimings::final_update_refs_finish_work);
1988
1989 // Finish updating references where we left off.
1990 clear_cancelled_concgc();
1991 ShenandoahHeapRegionSet* update_regions = regions();
1992 update_heap_references(update_regions, false);
1993 }
1994
1995 assert(! cancelled_concgc(), "Should have been done right before");
1996 concurrentMark()->update_roots(ShenandoahPhaseTimings::final_update_refs_roots);
1997
1998 if (ShenandoahStringDedup::is_enabled()) {
1999 ShenandoahGCPhase final_str_dedup_table(ShenandoahPhaseTimings::final_update_refs_dedup_table);
2000 ShenandoahStringDedup::parallel_update_refs();
2001 }
2002
2003 // Allocations might have happened before we STWed here, record peak:
2004 shenandoahPolicy()->record_peak_occupancy();
2005
2006 ShenandoahGCPhase final_update_refs(ShenandoahPhaseTimings::final_update_refs_recycle);
2007
2008 trash_cset_regions();
2009 set_need_update_refs(false);
2010
2011 if (ShenandoahVerify) {
2012 verifier()->verify_after_updaterefs();
2013 }
2014
2015 {
2016 // Rebuild the free set
2017 ShenandoahHeapLocker locker(lock());
2018 _free_regions->clear();
2019 size_t end = _ordered_regions->active_regions();
2020 for (size_t i = 0; i < end; i++) {
2021 ShenandoahHeapRegion* r = _ordered_regions->get(i);
2022 if (r->is_alloc_allowed()) {
2023 assert (!in_collection_set(r), "collection set should be clear");
2024 _free_regions->add_region(r);
2025 }
2026 }
2027 }
2028 set_update_refs_in_progress(false);
2029 }
2030
2031 void ShenandoahHeap::set_alloc_seq_gc_start() {
2032 // Take next number, the start seq number is inclusive
2033 _alloc_seq_at_last_gc_start = ShenandoahHeapRegion::alloc_seq_num() + 1;
2034 }
2035
2036 void ShenandoahHeap::set_alloc_seq_gc_end() {
2037 // Take current number, the end seq number is also inclusive
2038 _alloc_seq_at_last_gc_end = ShenandoahHeapRegion::alloc_seq_num();
2039 }
2040
2041
2042 #ifdef ASSERT
2043 void ShenandoahHeap::assert_heaplock_owned_by_current_thread() {
2044 _lock.assert_owned_by_current_thread();
2045 }
2046
2047 void ShenandoahHeap::assert_heaplock_not_owned_by_current_thread() {
2048 _lock.assert_not_owned_by_current_thread();
2049 }
2050
2051 void ShenandoahHeap::assert_heaplock_or_safepoint() {
2052 _lock.assert_owned_by_current_thread_or_safepoint();
2053 }
2054 #endif
2055
2056 void ShenandoahHeap::recycle_trash_assist(size_t limit) {
2057 assert_heaplock_owned_by_current_thread();
2058
2059 size_t count = 0;
2060 for (size_t i = 0; (i < num_regions()) && (count < limit); i++) {
2061 ShenandoahHeapRegion *r = _ordered_regions->get(i);
2062 if (r->is_trash()) {
2063 decrease_used(r->used());
2064 r->recycle();
2065 _free_regions->add_region(r);
2066 count++;
2067 }
2068 }
2069 }
2070
2071 void ShenandoahHeap::recycle_trash() {
2072 // lock is not reentrable, check we don't have it
2073 assert_heaplock_not_owned_by_current_thread();
2074
2075 size_t bytes_reclaimed = 0;
2076
2077 if (UseShenandoahMatrix) {
2078 // The complication for matrix cleanup is that we want the batched update
2079 // to alleviate costs. We also cannot add regions to freeset until matrix
2080 // is clean, otherwise we race with the actual allocations.
2081
2082 size_t count = 0;
2083 for (size_t i = 0; i < num_regions(); i++) {
2084 ShenandoahHeapRegion* r = _ordered_regions->get(i);
2085 if (r->is_trash()) {
2086 ShenandoahHeapLocker locker(lock());
2087 if (r->is_trash()) {
2088 bytes_reclaimed += r->used();
2089 decrease_used(r->used());
2090 r->recycle_no_matrix();
2091 _recycled_regions[count++] = r->region_number();
2092 }
2093 }
2094 SpinPause(); // allow allocators to barge the lock
2095 }
2096
2097 connection_matrix()->clear_batched(_recycled_regions, count);
2098
2099 {
2100 ShenandoahHeapLocker locker(lock());
2101 for (size_t i = 0; i < count; i++) {
2102 ShenandoahHeapRegion *r = _ordered_regions->get(_recycled_regions[i]);
2103 _free_regions->add_region(r);
2104 }
2105 }
2106
2107 } else {
2108 for (size_t i = 0; i < num_regions(); i++) {
2109 ShenandoahHeapRegion* r = _ordered_regions->get(i);
2110 if (r->is_trash()) {
2111 ShenandoahHeapLocker locker(lock());
2112 if (r->is_trash()) {
2113 bytes_reclaimed += r->used();
2114 decrease_used(r->used());
2115 r->recycle();
2116 _free_regions->add_region(r);
2117 }
2118 }
2119 SpinPause(); // allow allocators to barge the lock
2120 }
2121 }
2122
2123 _shenandoah_policy->record_bytes_reclaimed(bytes_reclaimed);
2124 }
2125
2126 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2127 print_on(st);
2128 print_heap_regions_on(st);
2129 }
2130
2131 address ShenandoahHeap::concurrent_mark_in_progress_addr() {
2132 return (address) &(ShenandoahHeap::heap()->_concurrent_mark_in_progress);
2133 }
2134
2135 bool ShenandoahHeap::commit_bitmaps(ShenandoahHeapRegion* r) {
2136 size_t len = _bitmap_words_per_region * HeapWordSize;
2137 size_t off = r->region_number() * _bitmap_words_per_region;
2138 if (!os::commit_memory((char*)(_bitmap_region.start() + off), len, false)) {
2139 return false;
2140 }
2141 return true;
2142 }
2143
2144 bool ShenandoahHeap::uncommit_bitmaps(ShenandoahHeapRegion* r) {
2145 size_t len = _bitmap_words_per_region * HeapWordSize;
2146 size_t off = r->region_number() * _bitmap_words_per_region;
2147 if (!os::uncommit_memory((char*)(_bitmap_region.start() + off), len)) {
2148 return false;
2149 }
2150 return true;
2151 }