1 /*
2 * Copyright (c) 2013, 2020, Red Hat, Inc. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.hpp"
27 #include "memory/universe.hpp"
28
29 #include "gc/shared/gcArguments.hpp"
30 #include "gc/shared/gcTimer.hpp"
31 #include "gc/shared/gcTraceTime.inline.hpp"
32 #include "gc/shared/locationPrinter.inline.hpp"
33 #include "gc/shared/memAllocator.hpp"
34 #include "gc/shared/oopStorageSet.hpp"
35 #include "gc/shared/plab.hpp"
36
37 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
38 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
39 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
40 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
41 #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
42 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
43 #include "gc/shenandoah/shenandoahControlThread.hpp"
44 #include "gc/shenandoah/shenandoahFreeSet.hpp"
45 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
46 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
47 #include "gc/shenandoah/shenandoahHeapRegion.inline.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/shenandoahOopClosures.inline.hpp"
55 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
56 #include "gc/shenandoah/shenandoahPadding.hpp"
57 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
58 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
59 #include "gc/shenandoah/shenandoahStringDedup.hpp"
60 #include "gc/shenandoah/shenandoahTaskqueue.hpp"
61 #include "gc/shenandoah/shenandoahUtils.hpp"
62 #include "gc/shenandoah/shenandoahVerifier.hpp"
63 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
64 #include "gc/shenandoah/shenandoahVMOperations.hpp"
65 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
66 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
67 #include "gc/shenandoah/mode/shenandoahIUMode.hpp"
68 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
69 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
70 #if INCLUDE_JFR
71 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
72 #endif
73
74 #include "memory/metaspace.hpp"
75 #include "oops/compressedOops.inline.hpp"
76 #include "runtime/atomic.hpp"
77 #include "runtime/globals.hpp"
78 #include "runtime/interfaceSupport.inline.hpp"
79 #include "runtime/orderAccess.hpp"
80 #include "runtime/safepointMechanism.hpp"
81 #include "runtime/vmThread.hpp"
82 #include "services/mallocTracker.hpp"
83 #include "utilities/powerOfTwo.hpp"
84
85 ShenandoahHeap* ShenandoahHeap::_heap = NULL;
86
87 #ifdef ASSERT
88 template <class T>
89 void ShenandoahAssertToSpaceClosure::do_oop_work(T* p) {
90 T o = RawAccess<>::oop_load(p);
91 if (! CompressedOops::is_null(o)) {
92 oop obj = CompressedOops::decode_not_null(o);
93 shenandoah_assert_not_forwarded(p, obj);
94 }
95 }
96
97 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_work(p); }
98 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_work(p); }
99 #endif
100
101 class ShenandoahPretouchHeapTask : public AbstractGangTask {
102 private:
103 ShenandoahRegionIterator _regions;
104 const size_t _page_size;
105 public:
106 ShenandoahPretouchHeapTask(size_t page_size) :
107 AbstractGangTask("Shenandoah Pretouch Heap"),
108 _page_size(page_size) {}
109
110 virtual void work(uint worker_id) {
111 ShenandoahHeapRegion* r = _regions.next();
112 while (r != NULL) {
113 os::pretouch_memory(r->bottom(), r->end(), _page_size);
114 r = _regions.next();
115 }
116 }
117 };
118
119 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
120 private:
121 ShenandoahRegionIterator _regions;
122 char* _bitmap_base;
123 const size_t _bitmap_size;
124 const size_t _page_size;
125 public:
126 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
127 AbstractGangTask("Shenandoah Pretouch Bitmap"),
128 _bitmap_base(bitmap_base),
129 _bitmap_size(bitmap_size),
130 _page_size(page_size) {}
131
132 virtual void work(uint worker_id) {
133 ShenandoahHeapRegion* r = _regions.next();
134 while (r != NULL) {
135 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
136 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
137 assert (end <= _bitmap_size, "end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size);
138
139 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end, _page_size);
140
141 r = _regions.next();
142 }
143 }
144 };
145
146 jint ShenandoahHeap::initialize() {
147 //
148 // Figure out heap sizing
149 //
150
151 size_t init_byte_size = InitialHeapSize;
152 size_t min_byte_size = MinHeapSize;
153 size_t max_byte_size = MaxHeapSize;
154 size_t heap_alignment = HeapAlignment;
155
156 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
157
158 if (ShenandoahAlwaysPreTouch) {
159 // Enabled pre-touch means the entire heap is committed right away.
160 init_byte_size = max_byte_size;
161 }
162
163 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
164 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
165
166 _num_regions = ShenandoahHeapRegion::region_count();
167
168 // Now we know the number of regions, initialize the heuristics.
169 initialize_heuristics();
170
171 size_t num_committed_regions = init_byte_size / reg_size_bytes;
172 num_committed_regions = MIN2(num_committed_regions, _num_regions);
173 assert(num_committed_regions <= _num_regions, "sanity");
174 _initial_size = num_committed_regions * reg_size_bytes;
175
176 size_t num_min_regions = min_byte_size / reg_size_bytes;
177 num_min_regions = MIN2(num_min_regions, _num_regions);
178 assert(num_min_regions <= _num_regions, "sanity");
179 _minimum_size = num_min_regions * reg_size_bytes;
180
181 _committed = _initial_size;
182
183 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
184 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
185 size_t region_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
186
187 //
188 // Reserve and commit memory for heap
189 //
190
191 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
192 initialize_reserved_region(heap_rs);
193 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
194 _heap_region_special = heap_rs.special();
195
196 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
197 "Misaligned heap: " PTR_FORMAT, p2i(base()));
198
199 #if SHENANDOAH_OPTIMIZED_OBJTASK
200 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
201 // Fail if we ever attempt to address more than we can.
202 if ((uintptr_t)heap_rs.end() >= ObjArrayChunkedTask::max_addressable()) {
203 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
204 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
205 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
206 p2i(heap_rs.base()), p2i(heap_rs.end()), ObjArrayChunkedTask::max_addressable());
207 vm_exit_during_initialization("Fatal Error", buf);
208 }
209 #endif
210
211 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
212 if (!_heap_region_special) {
213 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
214 "Cannot commit heap memory");
215 }
216
217 //
218 // Reserve and commit memory for bitmap(s)
219 //
220
221 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
222 _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
223
224 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
225
226 guarantee(bitmap_bytes_per_region != 0,
227 "Bitmap bytes per region should not be zero");
228 guarantee(is_power_of_2(bitmap_bytes_per_region),
229 "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
230
231 if (bitmap_page_size > bitmap_bytes_per_region) {
232 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
233 _bitmap_bytes_per_slice = bitmap_page_size;
234 } else {
235 _bitmap_regions_per_slice = 1;
236 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
237 }
238
239 guarantee(_bitmap_regions_per_slice >= 1,
240 "Should have at least one region per slice: " SIZE_FORMAT,
241 _bitmap_regions_per_slice);
242
243 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
244 "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
245 _bitmap_bytes_per_slice, bitmap_page_size);
246
247 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
248 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
249 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
250 _bitmap_region_special = bitmap.special();
251
252 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
253 align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
254 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
255 if (!_bitmap_region_special) {
256 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
257 "Cannot commit bitmap memory");
258 }
259
260 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
261
262 if (ShenandoahVerify) {
263 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
264 if (!verify_bitmap.special()) {
265 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
266 "Cannot commit verification bitmap memory");
267 }
268 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
269 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
270 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
271 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
272 }
273
274 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
275 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
276 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
277 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
278 _aux_bitmap_region_special = aux_bitmap.special();
279 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
280
281 //
282 // Create regions and region sets
283 //
284 size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
285 size_t region_storage_size = align_up(region_align * _num_regions, region_page_size);
286 region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity());
287
288 ReservedSpace region_storage(region_storage_size, region_page_size);
289 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
290 if (!region_storage.special()) {
291 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
292 "Cannot commit region memory");
293 }
294
295 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks.
296 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there.
297 // If not successful, bite a bullet and allocate at whatever address.
298 {
299 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
300 size_t cset_size = align_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align);
301
302 uintptr_t min = round_up_power_of_2(cset_align);
303 uintptr_t max = (1u << 30u);
304
305 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
306 char* req_addr = (char*)addr;
307 assert(is_aligned(req_addr, cset_align), "Should be aligned");
308 ReservedSpace cset_rs(cset_size, os::vm_page_size(), false, req_addr);
309 if (cset_rs.is_reserved()) {
310 assert(cset_rs.base() == req_addr, "Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr);
311 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
312 break;
313 }
314 }
315
316 if (_collection_set == NULL) {
317 ReservedSpace cset_rs(cset_size, os::vm_page_size(), false);
318 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
319 }
320 }
321
322 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
323 _free_set = new ShenandoahFreeSet(this, _num_regions);
324
325 {
326 ShenandoahHeapLocker locker(lock());
327
328 for (size_t i = 0; i < _num_regions; i++) {
329 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
330 bool is_committed = i < num_committed_regions;
331 void* loc = region_storage.base() + i * region_align;
332
333 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
334 assert(is_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
335
336 _marking_context->initialize_top_at_mark_start(r);
337 _regions[i] = r;
338 assert(!collection_set()->is_in(i), "New region should not be in collection set");
339 }
340
341 // Initialize to complete
342 _marking_context->mark_complete();
343
344 _free_set->rebuild();
345 }
346
347 if (ShenandoahAlwaysPreTouch) {
348 assert(!AlwaysPreTouch, "Should have been overridden");
349
350 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
351 // before initialize() below zeroes it with initializing thread. For any given region,
352 // we touch the region and the corresponding bitmaps from the same thread.
353 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
354
355 size_t pretouch_heap_page_size = heap_page_size;
356 size_t pretouch_bitmap_page_size = bitmap_page_size;
357
358 #ifdef LINUX
359 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
360 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
361 // them into huge one. Therefore, we need to pretouch with smaller pages.
362 if (UseTransparentHugePages) {
363 pretouch_heap_page_size = (size_t)os::vm_page_size();
364 pretouch_bitmap_page_size = (size_t)os::vm_page_size();
365 }
366 #endif
367
368 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
369 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
370
371 log_info(gc, init)("Pretouch bitmap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
372 _num_regions, pretouch_bitmap_page_size);
373 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, pretouch_bitmap_page_size);
374 _workers->run_task(&bcl);
375
376 log_info(gc, init)("Pretouch heap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
377 _num_regions, pretouch_heap_page_size);
378 ShenandoahPretouchHeapTask hcl(pretouch_heap_page_size);
379 _workers->run_task(&hcl);
380 }
381
382 //
383 // Initialize the rest of GC subsystems
384 //
385
386 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
387 for (uint worker = 0; worker < _max_workers; worker++) {
388 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
389 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
390 }
391
392 // There should probably be Shenandoah-specific options for these,
393 // just as there are G1-specific options.
394 {
395 ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
396 satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
397 satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
398 }
399
400 _monitoring_support = new ShenandoahMonitoringSupport(this);
401 _phase_timings = new ShenandoahPhaseTimings(max_workers());
402 ShenandoahStringDedup::initialize();
403 ShenandoahCodeRoots::initialize();
404
405 if (ShenandoahPacing) {
406 _pacer = new ShenandoahPacer(this);
407 _pacer->setup_for_idle();
408 } else {
409 _pacer = NULL;
410 }
411
412 _control_thread = new ShenandoahControlThread();
413
414 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max",
415 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size),
416 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size),
417 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity())
418 );
419
420 log_info(gc, init)("Safepointing mechanism: thread-local poll");
421
422 return JNI_OK;
423 }
424
425 void ShenandoahHeap::initialize_heuristics() {
426 if (ShenandoahGCMode != NULL) {
427 if (strcmp(ShenandoahGCMode, "satb") == 0) {
428 _gc_mode = new ShenandoahSATBMode();
429 } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
430 _gc_mode = new ShenandoahIUMode();
431 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
432 _gc_mode = new ShenandoahPassiveMode();
433 } else {
434 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
435 }
436 } else {
437 ShouldNotReachHere();
438 }
439 _gc_mode->initialize_flags();
440 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
441 vm_exit_during_initialization(
442 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
443 _gc_mode->name()));
444 }
445 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
446 vm_exit_during_initialization(
447 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
448 _gc_mode->name()));
449 }
450 log_info(gc, init)("Shenandoah GC mode: %s",
451 _gc_mode->name());
452
453 _heuristics = _gc_mode->initialize_heuristics();
454
455 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
456 vm_exit_during_initialization(
457 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
458 _heuristics->name()));
459 }
460 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
461 vm_exit_during_initialization(
462 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
463 _heuristics->name()));
464 }
465 log_info(gc, init)("Shenandoah heuristics: %s",
466 _heuristics->name());
467 }
468
469 #ifdef _MSC_VER
470 #pragma warning( push )
471 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
472 #endif
473
474 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
475 CollectedHeap(),
476 _initial_size(0),
477 _used(0),
478 _committed(0),
479 _bytes_allocated_since_gc_start(0),
480 _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
481 _workers(NULL),
482 _safepoint_workers(NULL),
483 _heap_region_special(false),
484 _num_regions(0),
485 _regions(NULL),
486 _update_refs_iterator(this),
487 _control_thread(NULL),
488 _shenandoah_policy(policy),
489 _heuristics(NULL),
490 _free_set(NULL),
491 _scm(new ShenandoahConcurrentMark()),
492 _full_gc(new ShenandoahMarkCompact()),
493 _pacer(NULL),
494 _verifier(NULL),
495 _phase_timings(NULL),
496 _monitoring_support(NULL),
497 _memory_pool(NULL),
498 _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
499 _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
500 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
501 _soft_ref_policy(),
502 _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
503 _ref_processor(NULL),
504 _marking_context(NULL),
505 _bitmap_size(0),
506 _bitmap_regions_per_slice(0),
507 _bitmap_bytes_per_slice(0),
508 _bitmap_region_special(false),
509 _aux_bitmap_region_special(false),
510 _liveness_cache(NULL),
511 _collection_set(NULL)
512 {
513 _heap = this;
514
515 log_info(gc, init)("GC threads: " UINT32_FORMAT " parallel, " UINT32_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
516
517 BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
518
519 _max_workers = MAX2(_max_workers, 1U);
520 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
521 /* are_GC_task_threads */ true,
522 /* are_ConcurrentGC_threads */ true);
523 if (_workers == NULL) {
524 vm_exit_during_initialization("Failed necessary allocation.");
525 } else {
526 _workers->initialize_workers();
527 }
528
529 if (ParallelGCThreads > 1) {
530 _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
531 ParallelGCThreads,
532 /* are_GC_task_threads */ false,
533 /* are_ConcurrentGC_threads */ false);
534 _safepoint_workers->initialize_workers();
535 }
536 }
537
538 #ifdef _MSC_VER
539 #pragma warning( pop )
540 #endif
541
542 class ShenandoahResetBitmapTask : public AbstractGangTask {
543 private:
544 ShenandoahRegionIterator _regions;
545
546 public:
547 ShenandoahResetBitmapTask() :
548 AbstractGangTask("Parallel Reset Bitmap Task") {}
549
550 void work(uint worker_id) {
551 ShenandoahHeapRegion* region = _regions.next();
552 ShenandoahHeap* heap = ShenandoahHeap::heap();
553 ShenandoahMarkingContext* const ctx = heap->marking_context();
554 while (region != NULL) {
555 if (heap->is_bitmap_slice_committed(region)) {
556 ctx->clear_bitmap(region);
557 }
558 region = _regions.next();
559 }
560 }
561 };
562
563 void ShenandoahHeap::reset_mark_bitmap() {
564 assert_gc_workers(_workers->active_workers());
565 mark_incomplete_marking_context();
566
567 ShenandoahResetBitmapTask task;
568 _workers->run_task(&task);
569 }
570
571 void ShenandoahHeap::print_on(outputStream* st) const {
572 st->print_cr("Shenandoah Heap");
573 st->print_cr(" " SIZE_FORMAT "%s total, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
574 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
575 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
576 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
577 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
578 num_regions(),
579 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
580 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
581
582 st->print("Status: ");
583 if (has_forwarded_objects()) st->print("has forwarded objects, ");
584 if (is_concurrent_mark_in_progress()) st->print("marking, ");
585 if (is_evacuation_in_progress()) st->print("evacuating, ");
586 if (is_update_refs_in_progress()) st->print("updating refs, ");
587 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
588 if (is_full_gc_in_progress()) st->print("full gc, ");
589 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
590 if (is_concurrent_weak_root_in_progress()) st->print("concurrent weak roots, ");
591 if (is_concurrent_strong_root_in_progress() &&
592 !is_concurrent_weak_root_in_progress()) st->print("concurrent strong roots, ");
593
594 if (cancelled_gc()) {
595 st->print("cancelled");
596 } else {
597 st->print("not cancelled");
598 }
599 st->cr();
600
601 st->print_cr("Reserved region:");
602 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
603 p2i(reserved_region().start()),
604 p2i(reserved_region().end()));
605
606 ShenandoahCollectionSet* cset = collection_set();
607 st->print_cr("Collection set:");
608 if (cset != NULL) {
609 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
610 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
611 } else {
612 st->print_cr(" (NULL)");
613 }
614
615 st->cr();
616 MetaspaceUtils::print_on(st);
617
618 if (Verbose) {
619 print_heap_regions_on(st);
620 }
621 }
622
623 class ShenandoahInitWorkerGCLABClosure : public ThreadClosure {
624 public:
625 void do_thread(Thread* thread) {
626 assert(thread != NULL, "Sanity");
627 assert(thread->is_Worker_thread(), "Only worker thread expected");
628 ShenandoahThreadLocalData::initialize_gclab(thread);
629 }
630 };
631
632 void ShenandoahHeap::post_initialize() {
633 CollectedHeap::post_initialize();
634 MutexLocker ml(Threads_lock);
635
636 ShenandoahInitWorkerGCLABClosure init_gclabs;
637 _workers->threads_do(&init_gclabs);
638
639 // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
640 // Now, we will let WorkGang to initialize gclab when new worker is created.
641 _workers->set_initialize_gclab();
642
643 _scm->initialize(_max_workers);
644 _full_gc->initialize(_gc_timer);
645
646 ref_processing_init();
647
648 _heuristics->initialize();
649
650 JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
651 }
652
653 size_t ShenandoahHeap::used() const {
654 return Atomic::load_acquire(&_used);
655 }
656
657 size_t ShenandoahHeap::committed() const {
658 OrderAccess::acquire();
659 return _committed;
660 }
661
662 void ShenandoahHeap::increase_committed(size_t bytes) {
663 shenandoah_assert_heaplocked_or_safepoint();
664 _committed += bytes;
665 }
666
667 void ShenandoahHeap::decrease_committed(size_t bytes) {
668 shenandoah_assert_heaplocked_or_safepoint();
669 _committed -= bytes;
670 }
671
672 void ShenandoahHeap::increase_used(size_t bytes) {
673 Atomic::add(&_used, bytes);
674 }
675
676 void ShenandoahHeap::set_used(size_t bytes) {
677 Atomic::release_store_fence(&_used, bytes);
678 }
679
680 void ShenandoahHeap::decrease_used(size_t bytes) {
681 assert(used() >= bytes, "never decrease heap size by more than we've left");
682 Atomic::sub(&_used, bytes);
683 }
684
685 void ShenandoahHeap::increase_allocated(size_t bytes) {
686 Atomic::add(&_bytes_allocated_since_gc_start, bytes);
687 }
688
689 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
690 size_t bytes = words * HeapWordSize;
691 if (!waste) {
692 increase_used(bytes);
693 }
694 increase_allocated(bytes);
695 if (ShenandoahPacing) {
696 control_thread()->pacing_notify_alloc(words);
697 if (waste) {
698 pacer()->claim_for_alloc(words, true);
699 }
700 }
701 }
702
703 size_t ShenandoahHeap::capacity() const {
704 return committed();
705 }
706
707 size_t ShenandoahHeap::max_capacity() const {
708 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
709 }
710
711 size_t ShenandoahHeap::min_capacity() const {
712 return _minimum_size;
713 }
714
715 size_t ShenandoahHeap::initial_capacity() const {
716 return _initial_size;
717 }
718
719 bool ShenandoahHeap::is_in(const void* p) const {
720 HeapWord* heap_base = (HeapWord*) base();
721 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
722 return p >= heap_base && p < last_region_end;
723 }
724
725 void ShenandoahHeap::op_uncommit(double shrink_before) {
726 assert (ShenandoahUncommit, "should be enabled");
727
728 // Application allocates from the beginning of the heap, and GC allocates at
729 // the end of it. It is more efficient to uncommit from the end, so that applications
730 // could enjoy the near committed regions. GC allocations are much less frequent,
731 // and therefore can accept the committing costs.
732
733 size_t count = 0;
734 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
735 ShenandoahHeapRegion* r = get_region(i - 1);
736 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
737 ShenandoahHeapLocker locker(lock());
738 if (r->is_empty_committed()) {
739 // Do not uncommit below minimal capacity
740 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
741 break;
742 }
743
744 r->make_uncommitted();
745 count++;
746 }
747 }
748 SpinPause(); // allow allocators to take the lock
749 }
750
751 if (count > 0) {
752 control_thread()->notify_heap_changed();
753 }
754 }
755
756 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
757 // New object should fit the GCLAB size
758 size_t min_size = MAX2(size, PLAB::min_size());
759
760 // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
761 size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
762 new_size = MIN2(new_size, PLAB::max_size());
763 new_size = MAX2(new_size, PLAB::min_size());
764
765 // Record new heuristic value even if we take any shortcut. This captures
766 // the case when moderately-sized objects always take a shortcut. At some point,
767 // heuristics should catch up with them.
768 ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
769
770 if (new_size < size) {
771 // New size still does not fit the object. Fall back to shared allocation.
772 // This avoids retiring perfectly good GCLABs, when we encounter a large object.
773 return NULL;
774 }
775
776 // Retire current GCLAB, and allocate a new one.
777 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
778 gclab->retire();
779
780 size_t actual_size = 0;
781 HeapWord* gclab_buf = allocate_new_gclab(min_size, new_size, &actual_size);
782 if (gclab_buf == NULL) {
783 return NULL;
784 }
785
786 assert (size <= actual_size, "allocation should fit");
787
788 if (ZeroTLAB) {
789 // ..and clear it.
790 Copy::zero_to_words(gclab_buf, actual_size);
791 } else {
792 // ...and zap just allocated object.
793 #ifdef ASSERT
794 // Skip mangling the space corresponding to the object header to
795 // ensure that the returned space is not considered parsable by
796 // any concurrent GC thread.
797 size_t hdr_size = oopDesc::header_size();
798 Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
799 #endif // ASSERT
800 }
801 gclab->set_buf(gclab_buf, actual_size);
802 return gclab->allocate(size);
803 }
804
805 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
806 size_t requested_size,
807 size_t* actual_size) {
808 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
809 HeapWord* res = allocate_memory(req);
810 if (res != NULL) {
811 *actual_size = req.actual_size();
812 } else {
813 *actual_size = 0;
814 }
815 return res;
816 }
817
818 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
819 size_t word_size,
820 size_t* actual_size) {
821 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
822 HeapWord* res = allocate_memory(req);
823 if (res != NULL) {
824 *actual_size = req.actual_size();
825 } else {
826 *actual_size = 0;
827 }
828 return res;
829 }
830
831 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
832 intptr_t pacer_epoch = 0;
833 bool in_new_region = false;
834 HeapWord* result = NULL;
835
836 if (req.is_mutator_alloc()) {
837 if (ShenandoahPacing) {
838 pacer()->pace_for_alloc(req.size());
839 pacer_epoch = pacer()->epoch();
840 }
841
842 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
843 result = allocate_memory_under_lock(req, in_new_region);
844 }
845
846 // Allocation failed, block until control thread reacted, then retry allocation.
847 //
848 // It might happen that one of the threads requesting allocation would unblock
849 // way later after GC happened, only to fail the second allocation, because
850 // other threads have already depleted the free storage. In this case, a better
851 // strategy is to try again, as long as GC makes progress.
852 //
853 // Then, we need to make sure the allocation was retried after at least one
854 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
855
856 size_t tries = 0;
857
858 while (result == NULL && _progress_last_gc.is_set()) {
859 tries++;
860 control_thread()->handle_alloc_failure(req);
861 result = allocate_memory_under_lock(req, in_new_region);
862 }
863
864 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
865 tries++;
866 control_thread()->handle_alloc_failure(req);
867 result = allocate_memory_under_lock(req, in_new_region);
868 }
869
870 } else {
871 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
872 result = allocate_memory_under_lock(req, in_new_region);
873 // Do not call handle_alloc_failure() here, because we cannot block.
874 // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
875 }
876
877 if (in_new_region) {
878 control_thread()->notify_heap_changed();
879 }
880
881 if (result != NULL) {
882 size_t requested = req.size();
883 size_t actual = req.actual_size();
884
885 assert (req.is_lab_alloc() || (requested == actual),
886 "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
887 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
888
889 if (req.is_mutator_alloc()) {
890 notify_mutator_alloc_words(actual, false);
891
892 // If we requested more than we were granted, give the rest back to pacer.
893 // This only matters if we are in the same pacing epoch: do not try to unpace
894 // over the budget for the other phase.
895 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
896 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
897 }
898 } else {
899 increase_used(actual*HeapWordSize);
900 }
901 }
902
903 return result;
904 }
905
906 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
907 ShenandoahHeapLocker locker(lock());
908 return _free_set->allocate(req, in_new_region);
909 }
910
911 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
912 bool* gc_overhead_limit_was_exceeded) {
913 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
914 return allocate_memory(req);
915 }
916
917 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
918 size_t size,
919 Metaspace::MetadataType mdtype) {
920 MetaWord* result;
921
922 // Inform metaspace OOM to GC heuristics if class unloading is possible.
923 if (heuristics()->can_unload_classes()) {
924 ShenandoahHeuristics* h = heuristics();
925 h->record_metaspace_oom();
926 }
927
928 // Expand and retry allocation
929 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
930 if (result != NULL) {
931 return result;
932 }
933
934 // Start full GC
935 collect(GCCause::_metadata_GC_clear_soft_refs);
936
937 // Retry allocation
938 result = loader_data->metaspace_non_null()->allocate(size, mdtype);
939 if (result != NULL) {
940 return result;
941 }
942
943 // Expand and retry allocation
944 result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
945 if (result != NULL) {
946 return result;
947 }
948
949 // Out of memory
950 return NULL;
951 }
952
953 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
954 private:
955 ShenandoahHeap* const _heap;
956 Thread* const _thread;
957 public:
958 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
959 _heap(heap), _thread(Thread::current()) {}
960
961 void do_object(oop p) {
962 shenandoah_assert_marked(NULL, p);
963 if (!p->is_forwarded()) {
964 _heap->evacuate_object(p, _thread);
965 }
966 }
967 };
968
969 class ShenandoahEvacuationTask : public AbstractGangTask {
970 private:
971 ShenandoahHeap* const _sh;
972 ShenandoahCollectionSet* const _cs;
973 bool _concurrent;
974 public:
975 ShenandoahEvacuationTask(ShenandoahHeap* sh,
976 ShenandoahCollectionSet* cs,
977 bool concurrent) :
978 AbstractGangTask("Parallel Evacuation Task"),
979 _sh(sh),
980 _cs(cs),
981 _concurrent(concurrent)
982 {}
983
984 void work(uint worker_id) {
985 if (_concurrent) {
986 ShenandoahConcurrentWorkerSession worker_session(worker_id);
987 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
988 ShenandoahEvacOOMScope oom_evac_scope;
989 do_work();
990 } else {
991 ShenandoahParallelWorkerSession worker_session(worker_id);
992 ShenandoahEvacOOMScope oom_evac_scope;
993 do_work();
994 }
995 }
996
997 private:
998 void do_work() {
999 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
1000 ShenandoahHeapRegion* r;
1001 while ((r =_cs->claim_next()) != NULL) {
1002 assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
1003 _sh->marked_object_iterate(r, &cl);
1004
1005 if (ShenandoahPacing) {
1006 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
1007 }
1008
1009 if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1010 break;
1011 }
1012 }
1013 }
1014 };
1015
1016 void ShenandoahHeap::trash_cset_regions() {
1017 ShenandoahHeapLocker locker(lock());
1018
1019 ShenandoahCollectionSet* set = collection_set();
1020 ShenandoahHeapRegion* r;
1021 set->clear_current_index();
1022 while ((r = set->next()) != NULL) {
1023 r->make_trash();
1024 }
1025 collection_set()->clear();
1026 }
1027
1028 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1029 st->print_cr("Heap Regions:");
1030 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
1031 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
1032 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark");
1033 st->print_cr("SN=alloc sequence number");
1034
1035 for (size_t i = 0; i < num_regions(); i++) {
1036 get_region(i)->print_on(st);
1037 }
1038 }
1039
1040 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1041 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1042
1043 oop humongous_obj = oop(start->bottom());
1044 size_t size = humongous_obj->size();
1045 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1046 size_t index = start->index() + required_regions - 1;
1047
1048 assert(!start->has_live(), "liveness must be zero");
1049
1050 for(size_t i = 0; i < required_regions; i++) {
1051 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1052 // as it expects that every region belongs to a humongous region starting with a humongous start region.
1053 ShenandoahHeapRegion* region = get_region(index --);
1054
1055 assert(region->is_humongous(), "expect correct humongous start or continuation");
1056 assert(!region->is_cset(), "Humongous region should not be in collection set");
1057
1058 region->make_trash_immediate();
1059 }
1060 }
1061
1062 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1063 public:
1064 void do_thread(Thread* thread) {
1065 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1066 assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1067 gclab->retire();
1068 }
1069 };
1070
1071 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
1072 if (UseTLAB) {
1073 CollectedHeap::ensure_parsability(retire_tlabs);
1074 }
1075 ShenandoahRetireGCLABClosure cl;
1076 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1077 cl.do_thread(t);
1078 }
1079 workers()->threads_do(&cl);
1080 }
1081
1082 void ShenandoahHeap::resize_tlabs() {
1083 CollectedHeap::resize_all_tlabs();
1084 }
1085
1086 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
1087 private:
1088 ShenandoahRootEvacuator* _rp;
1089
1090 public:
1091 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
1092 AbstractGangTask("Shenandoah evacuate and update roots"),
1093 _rp(rp) {}
1094
1095 void work(uint worker_id) {
1096 ShenandoahParallelWorkerSession worker_session(worker_id);
1097 ShenandoahEvacOOMScope oom_evac_scope;
1098 ShenandoahEvacuateUpdateRootsClosure<> cl;
1099 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
1100 _rp->roots_do(worker_id, &cl);
1101 }
1102 };
1103
1104 void ShenandoahHeap::evacuate_and_update_roots() {
1105 #if COMPILER2_OR_JVMCI
1106 DerivedPointerTable::clear();
1107 #endif
1108 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1109 {
1110 // Include concurrent roots if current cycle can not process those roots concurrently
1111 ShenandoahRootEvacuator rp(workers()->active_workers(),
1112 ShenandoahPhaseTimings::init_evac,
1113 !ShenandoahConcurrentRoots::should_do_concurrent_roots(),
1114 !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
1115 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1116 workers()->run_task(&roots_task);
1117 }
1118
1119 #if COMPILER2_OR_JVMCI
1120 DerivedPointerTable::update_pointers();
1121 #endif
1122 }
1123
1124 // Returns size in bytes
1125 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1126 if (ShenandoahElasticTLAB) {
1127 // With Elastic TLABs, return the max allowed size, and let the allocation path
1128 // figure out the safe size for current allocation.
1129 return ShenandoahHeapRegion::max_tlab_size_bytes();
1130 } else {
1131 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1132 }
1133 }
1134
1135 size_t ShenandoahHeap::max_tlab_size() const {
1136 // Returns size in words
1137 return ShenandoahHeapRegion::max_tlab_size_words();
1138 }
1139
1140 class ShenandoahRetireAndResetGCLABClosure : public ThreadClosure {
1141 public:
1142 void do_thread(Thread* thread) {
1143 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1144 gclab->retire();
1145 if (ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1146 ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1147 }
1148 }
1149 };
1150
1151 void ShenandoahHeap::retire_and_reset_gclabs() {
1152 ShenandoahRetireAndResetGCLABClosure cl;
1153 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1154 cl.do_thread(t);
1155 }
1156 workers()->threads_do(&cl);
1157 }
1158
1159 void ShenandoahHeap::collect(GCCause::Cause cause) {
1160 control_thread()->request_gc(cause);
1161 }
1162
1163 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1164 //assert(false, "Shouldn't need to do full collections");
1165 }
1166
1167 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1168 ShenandoahHeapRegion* r = heap_region_containing(addr);
1169 if (r != NULL) {
1170 return r->block_start(addr);
1171 }
1172 return NULL;
1173 }
1174
1175 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1176 ShenandoahHeapRegion* r = heap_region_containing(addr);
1177 return r->block_is_obj(addr);
1178 }
1179
1180 bool ShenandoahHeap::print_location(outputStream* st, void* addr) const {
1181 return BlockLocationPrinter<ShenandoahHeap>::print_location(st, addr);
1182 }
1183
1184 jlong ShenandoahHeap::millis_since_last_gc() {
1185 double v = heuristics()->time_since_last_gc() * 1000;
1186 assert(0 <= v && v <= max_jlong, "value should fit: %f", v);
1187 return (jlong)v;
1188 }
1189
1190 void ShenandoahHeap::prepare_for_verify() {
1191 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1192 make_parsable(false);
1193 }
1194 }
1195
1196 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1197 workers()->print_worker_threads_on(st);
1198 if (ShenandoahStringDedup::is_enabled()) {
1199 ShenandoahStringDedup::print_worker_threads_on(st);
1200 }
1201 }
1202
1203 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1204 workers()->threads_do(tcl);
1205 if (_safepoint_workers != NULL) {
1206 _safepoint_workers->threads_do(tcl);
1207 }
1208 if (ShenandoahStringDedup::is_enabled()) {
1209 ShenandoahStringDedup::threads_do(tcl);
1210 }
1211 }
1212
1213 void ShenandoahHeap::print_tracing_info() const {
1214 LogTarget(Info, gc, stats) lt;
1215 if (lt.is_enabled()) {
1216 ResourceMark rm;
1217 LogStream ls(lt);
1218
1219 phase_timings()->print_global_on(&ls);
1220
1221 ls.cr();
1222 ls.cr();
1223
1224 shenandoah_policy()->print_gc_stats(&ls);
1225
1226 ls.cr();
1227 ls.cr();
1228
1229 if (ShenandoahPacing) {
1230 pacer()->print_on(&ls);
1231 }
1232
1233 ls.cr();
1234 ls.cr();
1235 }
1236 }
1237
1238 void ShenandoahHeap::verify(VerifyOption vo) {
1239 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
1240 if (ShenandoahVerify) {
1241 verifier()->verify_generic(vo);
1242 } else {
1243 // TODO: Consider allocating verification bitmaps on demand,
1244 // and turn this on unconditionally.
1245 }
1246 }
1247 }
1248 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1249 return _free_set->capacity();
1250 }
1251
1252 class ObjectIterateScanRootClosure : public BasicOopIterateClosure {
1253 private:
1254 MarkBitMap* _bitmap;
1255 Stack<oop,mtGC>* _oop_stack;
1256 ShenandoahHeap* const _heap;
1257 ShenandoahMarkingContext* const _marking_context;
1258
1259 template <class T>
1260 void do_oop_work(T* p) {
1261 T o = RawAccess<>::oop_load(p);
1262 if (!CompressedOops::is_null(o)) {
1263 oop obj = CompressedOops::decode_not_null(o);
1264 if (_heap->is_concurrent_weak_root_in_progress() && !_marking_context->is_marked(obj)) {
1265 // There may be dead oops in weak roots in concurrent root phase, do not touch them.
1266 return;
1267 }
1268 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1269
1270 assert(oopDesc::is_oop(obj), "must be a valid oop");
1271 if (!_bitmap->is_marked(obj)) {
1272 _bitmap->mark(obj);
1273 _oop_stack->push(obj);
1274 }
1275 }
1276 }
1277 public:
1278 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1279 _bitmap(bitmap), _oop_stack(oop_stack), _heap(ShenandoahHeap::heap()),
1280 _marking_context(_heap->marking_context()) {}
1281 void do_oop(oop* p) { do_oop_work(p); }
1282 void do_oop(narrowOop* p) { do_oop_work(p); }
1283 };
1284
1285 /*
1286 * This is public API, used in preparation of object_iterate().
1287 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1288 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1289 * control, we call SH::make_tlabs_parsable().
1290 */
1291 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1292 // No-op.
1293 }
1294
1295 /*
1296 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1297 *
1298 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1299 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1300 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1301 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1302 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1303 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1304 * wiped the bitmap in preparation for next marking).
1305 *
1306 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1307 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1308 * is allowed to report dead objects, but is not required to do so.
1309 */
1310 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1311 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1312 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1313 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1314 return;
1315 }
1316
1317 // Reset bitmap
1318 _aux_bit_map.clear();
1319
1320 Stack<oop,mtGC> oop_stack;
1321
1322 // First, we process GC roots according to current GC cycle. This populates the work stack with initial objects.
1323 ShenandoahHeapIterationRootScanner rp;
1324 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1325
1326 rp.roots_do(&oops);
1327
1328 // Work through the oop stack to traverse heap.
1329 while (! oop_stack.is_empty()) {
1330 oop obj = oop_stack.pop();
1331 assert(oopDesc::is_oop(obj), "must be a valid oop");
1332 cl->do_object(obj);
1333 obj->oop_iterate(&oops);
1334 }
1335
1336 assert(oop_stack.is_empty(), "should be empty");
1337
1338 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1339 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1340 }
1341 }
1342
1343 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1344 void ShenandoahHeap::keep_alive(oop obj) {
1345 if (is_concurrent_mark_in_progress()) {
1346 ShenandoahBarrierSet::barrier_set()->enqueue(obj);
1347 }
1348 }
1349
1350 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1351 for (size_t i = 0; i < num_regions(); i++) {
1352 ShenandoahHeapRegion* current = get_region(i);
1353 blk->heap_region_do(current);
1354 }
1355 }
1356
1357 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1358 private:
1359 ShenandoahHeap* const _heap;
1360 ShenandoahHeapRegionClosure* const _blk;
1361
1362 shenandoah_padding(0);
1363 volatile size_t _index;
1364 shenandoah_padding(1);
1365
1366 public:
1367 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1368 AbstractGangTask("Parallel Region Task"),
1369 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1370
1371 void work(uint worker_id) {
1372 ShenandoahParallelWorkerSession worker_session(worker_id);
1373 size_t stride = ShenandoahParallelRegionStride;
1374
1375 size_t max = _heap->num_regions();
1376 while (_index < max) {
1377 size_t cur = Atomic::fetch_and_add(&_index, stride);
1378 size_t start = cur;
1379 size_t end = MIN2(cur + stride, max);
1380 if (start >= max) break;
1381
1382 for (size_t i = cur; i < end; i++) {
1383 ShenandoahHeapRegion* current = _heap->get_region(i);
1384 _blk->heap_region_do(current);
1385 }
1386 }
1387 }
1388 };
1389
1390 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1391 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1392 if (num_regions() > ShenandoahParallelRegionStride) {
1393 ShenandoahParallelHeapRegionTask task(blk);
1394 workers()->run_task(&task);
1395 } else {
1396 heap_region_iterate(blk);
1397 }
1398 }
1399
1400 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1401 private:
1402 ShenandoahMarkingContext* const _ctx;
1403 public:
1404 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1405
1406 void heap_region_do(ShenandoahHeapRegion* r) {
1407 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1408 if (r->is_active()) {
1409 // Check if region needs updating its TAMS. We have updated it already during concurrent
1410 // reset, so it is very likely we don't need to do another write here.
1411 if (_ctx->top_at_mark_start(r) != r->top()) {
1412 _ctx->capture_top_at_mark_start(r);
1413 }
1414 } else {
1415 assert(_ctx->top_at_mark_start(r) == r->top(),
1416 "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1417 }
1418 }
1419
1420 bool is_thread_safe() { return true; }
1421 };
1422
1423 void ShenandoahHeap::op_init_mark() {
1424 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1425 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1426
1427 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1428 assert(!marking_context()->is_complete(), "should not be complete");
1429 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1430
1431 if (ShenandoahVerify) {
1432 verifier()->verify_before_concmark();
1433 }
1434
1435 if (VerifyBeforeGC) {
1436 Universe::verify();
1437 }
1438
1439 set_concurrent_mark_in_progress(true);
1440 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1441 {
1442 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1443 make_parsable(true);
1444 }
1445
1446 {
1447 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_region_states);
1448 ShenandoahInitMarkUpdateRegionStateClosure cl;
1449 parallel_heap_region_iterate(&cl);
1450 }
1451
1452 // Make above changes visible to worker threads
1453 OrderAccess::fence();
1454
1455 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1456
1457 if (UseTLAB) {
1458 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1459 resize_tlabs();
1460 }
1461
1462 if (ShenandoahPacing) {
1463 pacer()->setup_for_mark();
1464 }
1465
1466 // Arm nmethods for concurrent marking. When a nmethod is about to be executed,
1467 // we need to make sure that all its metadata are marked. alternative is to remark
1468 // thread roots at final mark pause, but it can be potential latency killer.
1469 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1470 ShenandoahCodeRoots::arm_nmethods();
1471 }
1472 }
1473
1474 void ShenandoahHeap::op_mark() {
1475 concurrent_mark()->mark_from_roots();
1476 }
1477
1478 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1479 private:
1480 ShenandoahMarkingContext* const _ctx;
1481 ShenandoahHeapLock* const _lock;
1482
1483 public:
1484 ShenandoahFinalMarkUpdateRegionStateClosure() :
1485 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1486
1487 void heap_region_do(ShenandoahHeapRegion* r) {
1488 if (r->is_active()) {
1489 // All allocations past TAMS are implicitly live, adjust the region data.
1490 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1491 HeapWord *tams = _ctx->top_at_mark_start(r);
1492 HeapWord *top = r->top();
1493 if (top > tams) {
1494 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1495 }
1496
1497 // We are about to select the collection set, make sure it knows about
1498 // current pinning status. Also, this allows trashing more regions that
1499 // now have their pinning status dropped.
1500 if (r->is_pinned()) {
1501 if (r->pin_count() == 0) {
1502 ShenandoahHeapLocker locker(_lock);
1503 r->make_unpinned();
1504 }
1505 } else {
1506 if (r->pin_count() > 0) {
1507 ShenandoahHeapLocker locker(_lock);
1508 r->make_pinned();
1509 }
1510 }
1511
1512 // Remember limit for updating refs. It's guaranteed that we get no
1513 // from-space-refs written from here on.
1514 r->set_update_watermark_at_safepoint(r->top());
1515 } else {
1516 assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1517 assert(_ctx->top_at_mark_start(r) == r->top(),
1518 "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1519 }
1520 }
1521
1522 bool is_thread_safe() { return true; }
1523 };
1524
1525 void ShenandoahHeap::op_final_mark() {
1526 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1527 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1528
1529 // It is critical that we
1530 // evacuate roots right after finishing marking, so that we don't
1531 // get unmarked objects in the roots.
1532
1533 if (!cancelled_gc()) {
1534 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1535
1536 // Marking is completed, deactivate SATB barrier
1537 set_concurrent_mark_in_progress(false);
1538 mark_complete_marking_context();
1539
1540 parallel_cleaning(false /* full gc*/);
1541
1542 if (ShenandoahVerify) {
1543 verifier()->verify_roots_no_forwarded();
1544 }
1545
1546 {
1547 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_region_states);
1548 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1549 parallel_heap_region_iterate(&cl);
1550
1551 assert_pinned_region_status();
1552 }
1553
1554 // Retire the TLABs, which will force threads to reacquire their TLABs after the pause.
1555 // This is needed for two reasons. Strong one: new allocations would be with new freeset,
1556 // which would be outside the collection set, so no cset writes would happen there.
1557 // Weaker one: new allocations would happen past update watermark, and so less work would
1558 // be needed for reference updates (would update the large filler instead).
1559 {
1560 ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs);
1561 make_parsable(true);
1562 }
1563
1564 {
1565 ShenandoahGCPhase phase(ShenandoahPhaseTimings::choose_cset);
1566 ShenandoahHeapLocker locker(lock());
1567 _collection_set->clear();
1568 heuristics()->choose_collection_set(_collection_set);
1569 }
1570
1571 {
1572 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_rebuild_freeset);
1573 ShenandoahHeapLocker locker(lock());
1574 _free_set->rebuild();
1575 }
1576
1577 if (!is_degenerated_gc_in_progress()) {
1578 prepare_concurrent_roots();
1579 prepare_concurrent_unloading();
1580 }
1581
1582 // If collection set has candidates, start evacuation.
1583 // Otherwise, bypass the rest of the cycle.
1584 if (!collection_set()->is_empty()) {
1585 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1586
1587 if (ShenandoahVerify) {
1588 verifier()->verify_before_evacuation();
1589 }
1590
1591 set_evacuation_in_progress(true);
1592 // From here on, we need to update references.
1593 set_has_forwarded_objects(true);
1594
1595 if (!is_degenerated_gc_in_progress()) {
1596 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1597 ShenandoahCodeRoots::arm_nmethods();
1598 }
1599 evacuate_and_update_roots();
1600 }
1601
1602 if (ShenandoahPacing) {
1603 pacer()->setup_for_evac();
1604 }
1605
1606 if (ShenandoahVerify) {
1607 ShenandoahRootVerifier::RootTypes types = ShenandoahRootVerifier::None;
1608 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
1609 types = ShenandoahRootVerifier::combine(ShenandoahRootVerifier::JNIHandleRoots, ShenandoahRootVerifier::WeakRoots);
1610 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CLDGRoots);
1611 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::StringDedupRoots);
1612 }
1613
1614 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1615 types = ShenandoahRootVerifier::combine(types, ShenandoahRootVerifier::CodeRoots);
1616 }
1617 verifier()->verify_roots_no_forwarded_except(types);
1618 verifier()->verify_during_evacuation();
1619 }
1620 } else {
1621 if (ShenandoahVerify) {
1622 verifier()->verify_after_concmark();
1623 }
1624
1625 if (VerifyAfterGC) {
1626 Universe::verify();
1627 }
1628 }
1629
1630 } else {
1631 // If this cycle was updating references, we need to keep the has_forwarded_objects
1632 // flag on, for subsequent phases to deal with it.
1633 concurrent_mark()->cancel();
1634 set_concurrent_mark_in_progress(false);
1635
1636 if (process_references()) {
1637 // Abandon reference processing right away: pre-cleaning must have failed.
1638 ReferenceProcessor *rp = ref_processor();
1639 rp->disable_discovery();
1640 rp->abandon_partial_discovery();
1641 rp->verify_no_references_recorded();
1642 }
1643 }
1644 }
1645
1646 void ShenandoahHeap::op_conc_evac() {
1647 ShenandoahEvacuationTask task(this, _collection_set, true);
1648 workers()->run_task(&task);
1649 }
1650
1651 void ShenandoahHeap::op_stw_evac() {
1652 ShenandoahEvacuationTask task(this, _collection_set, false);
1653 workers()->run_task(&task);
1654 }
1655
1656 void ShenandoahHeap::op_updaterefs() {
1657 update_heap_references(true);
1658 }
1659
1660 void ShenandoahHeap::op_cleanup_early() {
1661 free_set()->recycle_trash();
1662 }
1663
1664 void ShenandoahHeap::op_cleanup_complete() {
1665 free_set()->recycle_trash();
1666 }
1667
1668 class ShenandoahConcurrentRootsEvacUpdateTask : public AbstractGangTask {
1669 private:
1670 ShenandoahVMRoots<true /*concurrent*/> _vm_roots;
1671 ShenandoahClassLoaderDataRoots<true /*concurrent*/, false /*single threaded*/> _cld_roots;
1672 ShenandoahConcurrentStringDedupRoots _dedup_roots;
1673
1674 public:
1675 ShenandoahConcurrentRootsEvacUpdateTask(ShenandoahPhaseTimings::Phase phase) :
1676 AbstractGangTask("Shenandoah Evacuate/Update Concurrent Strong Roots Task"),
1677 _vm_roots(phase),
1678 _cld_roots(phase) {}
1679
1680 void work(uint worker_id) {
1681 ShenandoahConcurrentWorkerSession worker_session(worker_id);
1682 ShenandoahEvacOOMScope oom;
1683 {
1684 // vm_roots and weak_roots are OopStorage backed roots, concurrent iteration
1685 // may race against OopStorage::release() calls.
1686 ShenandoahEvacUpdateOopStorageRootsClosure cl;
1687 _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl, worker_id);
1688 }
1689
1690 {
1691 ShenandoahEvacuateUpdateRootsClosure<> cl;
1692 CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
1693 _cld_roots.cld_do(&clds, worker_id);
1694 }
1695
1696 {
1697 ShenandoahForwardedIsAliveClosure is_alive;
1698 ShenandoahEvacuateUpdateRootsClosure<MO_RELEASE> keep_alive;
1699 _dedup_roots.oops_do(&is_alive, &keep_alive, worker_id);
1700 }
1701 }
1702 };
1703
1704 class ShenandoahEvacUpdateCleanupOopStorageRootsClosure : public BasicOopIterateClosure {
1705 private:
1706 ShenandoahHeap* const _heap;
1707 ShenandoahMarkingContext* const _mark_context;
1708 bool _evac_in_progress;
1709 Thread* const _thread;
1710 size_t _dead_counter;
1711
1712 public:
1713 ShenandoahEvacUpdateCleanupOopStorageRootsClosure();
1714 void do_oop(oop* p);
1715 void do_oop(narrowOop* p);
1716
1717 size_t dead_counter() const;
1718 void reset_dead_counter();
1719 };
1720
1721 ShenandoahEvacUpdateCleanupOopStorageRootsClosure::ShenandoahEvacUpdateCleanupOopStorageRootsClosure() :
1722 _heap(ShenandoahHeap::heap()),
1723 _mark_context(ShenandoahHeap::heap()->marking_context()),
1724 _evac_in_progress(ShenandoahHeap::heap()->is_evacuation_in_progress()),
1725 _thread(Thread::current()),
1726 _dead_counter(0) {
1727 }
1728
1729 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(oop* p) {
1730 const oop obj = RawAccess<>::oop_load(p);
1731 if (!CompressedOops::is_null(obj)) {
1732 if (!_mark_context->is_marked(obj)) {
1733 shenandoah_assert_correct(p, obj);
1734 oop old = Atomic::cmpxchg(p, obj, oop(NULL));
1735 if (obj == old) {
1736 _dead_counter ++;
1737 }
1738 } else if (_evac_in_progress && _heap->in_collection_set(obj)) {
1739 oop resolved = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1740 if (resolved == obj) {
1741 resolved = _heap->evacuate_object(obj, _thread);
1742 }
1743 Atomic::cmpxchg(p, obj, resolved);
1744 assert(_heap->cancelled_gc() ||
1745 _mark_context->is_marked(resolved) && !_heap->in_collection_set(resolved),
1746 "Sanity");
1747 }
1748 }
1749 }
1750
1751 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::do_oop(narrowOop* p) {
1752 ShouldNotReachHere();
1753 }
1754
1755 size_t ShenandoahEvacUpdateCleanupOopStorageRootsClosure::dead_counter() const {
1756 return _dead_counter;
1757 }
1758
1759 void ShenandoahEvacUpdateCleanupOopStorageRootsClosure::reset_dead_counter() {
1760 _dead_counter = 0;
1761 }
1762
1763 class ShenandoahIsCLDAliveClosure : public CLDClosure {
1764 public:
1765 void do_cld(ClassLoaderData* cld) {
1766 cld->is_alive();
1767 }
1768 };
1769
1770 class ShenandoahIsNMethodAliveClosure: public NMethodClosure {
1771 public:
1772 void do_nmethod(nmethod* n) {
1773 n->is_unloading();
1774 }
1775 };
1776
1777 // This task not only evacuates/updates marked weak roots, but also "NULL"
1778 // dead weak roots.
1779 class ShenandoahConcurrentWeakRootsEvacUpdateTask : public AbstractGangTask {
1780 private:
1781 ShenandoahWeakRoot<true /*concurrent*/> _jni_roots;
1782 ShenandoahWeakRoot<true /*concurrent*/> _string_table_roots;
1783 ShenandoahWeakRoot<true /*concurrent*/> _resolved_method_table_roots;
1784 ShenandoahWeakRoot<true /*concurrent*/> _vm_roots;
1785
1786 // Roots related to concurrent class unloading
1787 ShenandoahClassLoaderDataRoots<true /* concurrent */, false /* single thread*/>
1788 _cld_roots;
1789 ShenandoahConcurrentNMethodIterator _nmethod_itr;
1790 bool _concurrent_class_unloading;
1791
1792 public:
1793 ShenandoahConcurrentWeakRootsEvacUpdateTask(ShenandoahPhaseTimings::Phase phase) :
1794 AbstractGangTask("Shenandoah Concurrent Weak Root Task"),
1795 _jni_roots(OopStorageSet::jni_weak(), phase, ShenandoahPhaseTimings::JNIWeakRoots),
1796 _string_table_roots(OopStorageSet::string_table_weak(), phase, ShenandoahPhaseTimings::StringTableRoots),
1797 _resolved_method_table_roots(OopStorageSet::resolved_method_table_weak(), phase, ShenandoahPhaseTimings::ResolvedMethodTableRoots),
1798 _vm_roots(OopStorageSet::vm_weak(), phase, ShenandoahPhaseTimings::VMWeakRoots),
1799 _cld_roots(phase),
1800 _nmethod_itr(ShenandoahCodeRoots::table()),
1801 _concurrent_class_unloading(ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1802 StringTable::reset_dead_counter();
1803 ResolvedMethodTable::reset_dead_counter();
1804 if (_concurrent_class_unloading) {
1805 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
1806 _nmethod_itr.nmethods_do_begin();
1807 }
1808 }
1809
1810 ~ShenandoahConcurrentWeakRootsEvacUpdateTask() {
1811 StringTable::finish_dead_counter();
1812 ResolvedMethodTable::finish_dead_counter();
1813 if (_concurrent_class_unloading) {
1814 MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
1815 _nmethod_itr.nmethods_do_end();
1816 }
1817 }
1818
1819 void work(uint worker_id) {
1820 ShenandoahConcurrentWorkerSession worker_session(worker_id);
1821 {
1822 ShenandoahEvacOOMScope oom;
1823 // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
1824 // may race against OopStorage::release() calls.
1825 ShenandoahEvacUpdateCleanupOopStorageRootsClosure cl;
1826 _jni_roots.oops_do(&cl, worker_id);
1827 _vm_roots.oops_do(&cl, worker_id);
1828
1829 cl.reset_dead_counter();
1830 _string_table_roots.oops_do(&cl, worker_id);
1831 StringTable::inc_dead_counter(cl.dead_counter());
1832
1833 cl.reset_dead_counter();
1834 _resolved_method_table_roots.oops_do(&cl, worker_id);
1835 ResolvedMethodTable::inc_dead_counter(cl.dead_counter());
1836 }
1837
1838 // If we are going to perform concurrent class unloading later on, we need to
1839 // cleanup the weak oops in CLD and determinate nmethod's unloading state, so that we
1840 // can cleanup immediate garbage sooner.
1841 if (_concurrent_class_unloading) {
1842 // Applies ShenandoahIsCLDAlive closure to CLDs, native barrier will either NULL the
1843 // CLD's holder or evacuate it.
1844 ShenandoahIsCLDAliveClosure is_cld_alive;
1845 _cld_roots.cld_do(&is_cld_alive, worker_id);
1846
1847 // Applies ShenandoahIsNMethodAliveClosure to registered nmethods.
1848 // The closure calls nmethod->is_unloading(). The is_unloading
1849 // state is cached, therefore, during concurrent class unloading phase,
1850 // we will not touch the metadata of unloading nmethods
1851 ShenandoahIsNMethodAliveClosure is_nmethod_alive;
1852 _nmethod_itr.nmethods_do(&is_nmethod_alive);
1853 }
1854 }
1855 };
1856
1857 void ShenandoahHeap::op_weak_roots() {
1858 if (is_concurrent_weak_root_in_progress()) {
1859 {
1860 // Concurrent weak root processing
1861 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_weak_roots_work);
1862 ShenandoahConcurrentWeakRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_weak_roots_work);
1863 workers()->run_task(&task);
1864 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
1865 set_concurrent_weak_root_in_progress(false);
1866 }
1867 }
1868
1869 // Perform handshake to flush out dead oops
1870 {
1871 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_weak_roots_rendezvous);
1872 ShenandoahRendezvousClosure cl;
1873 Handshake::execute(&cl);
1874 }
1875 }
1876 }
1877
1878 void ShenandoahHeap::op_class_unloading() {
1879 assert (is_concurrent_weak_root_in_progress() &&
1880 ShenandoahConcurrentRoots::should_do_concurrent_class_unloading(),
1881 "Checked by caller");
1882 _unloader.unload();
1883 set_concurrent_weak_root_in_progress(false);
1884 }
1885
1886 void ShenandoahHeap::op_strong_roots() {
1887 assert(is_concurrent_strong_root_in_progress(), "Checked by caller");
1888 ShenandoahConcurrentRootsEvacUpdateTask task(ShenandoahPhaseTimings::conc_strong_roots);
1889 workers()->run_task(&task);
1890 set_concurrent_strong_root_in_progress(false);
1891 }
1892
1893 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1894 private:
1895 ShenandoahMarkingContext* const _ctx;
1896 public:
1897 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1898
1899 void heap_region_do(ShenandoahHeapRegion* r) {
1900 if (r->is_active()) {
1901 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1902 // anyway to capture any updates that happened since now.
1903 r->clear_live_data();
1904 _ctx->capture_top_at_mark_start(r);
1905 }
1906 }
1907
1908 bool is_thread_safe() { return true; }
1909 };
1910
1911 void ShenandoahHeap::op_reset() {
1912 if (ShenandoahPacing) {
1913 pacer()->setup_for_reset();
1914 }
1915 reset_mark_bitmap();
1916
1917 ShenandoahResetUpdateRegionStateClosure cl;
1918 parallel_heap_region_iterate(&cl);
1919 }
1920
1921 void ShenandoahHeap::op_preclean() {
1922 if (ShenandoahPacing) {
1923 pacer()->setup_for_preclean();
1924 }
1925 concurrent_mark()->preclean_weak_refs();
1926 }
1927
1928 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1929 ShenandoahMetricsSnapshot metrics;
1930 metrics.snap_before();
1931
1932 full_gc()->do_it(cause);
1933 if (UseTLAB) {
1934 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_resize_tlabs);
1935 resize_all_tlabs();
1936 }
1937
1938 metrics.snap_after();
1939
1940 if (metrics.is_good_progress()) {
1941 _progress_last_gc.set();
1942 } else {
1943 // Nothing to do. Tell the allocation path that we have failed to make
1944 // progress, and it can finally fail.
1945 _progress_last_gc.unset();
1946 }
1947 }
1948
1949 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1950 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1951 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1952 // some phase, we have to upgrade the Degenerate GC to Full GC.
1953
1954 clear_cancelled_gc();
1955
1956 ShenandoahMetricsSnapshot metrics;
1957 metrics.snap_before();
1958
1959 switch (point) {
1960 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1961 // but enters it at different points, depending on which concurrent phase had
1962 // degenerated.
1963
1964 case _degenerated_outside_cycle:
1965 // We have degenerated from outside the cycle, which means something is bad with
1966 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1967 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1968 // we can do the most aggressive degen cycle, which includes processing references and
1969 // class unloading, unless those features are explicitly disabled.
1970 //
1971 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1972 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1973 set_process_references(heuristics()->can_process_references());
1974 set_unload_classes(heuristics()->can_unload_classes());
1975
1976 op_reset();
1977
1978 op_init_mark();
1979 if (cancelled_gc()) {
1980 op_degenerated_fail();
1981 return;
1982 }
1983
1984 case _degenerated_mark:
1985 op_final_mark();
1986 if (cancelled_gc()) {
1987 op_degenerated_fail();
1988 return;
1989 }
1990
1991 if (!has_forwarded_objects() && ShenandoahConcurrentRoots::can_do_concurrent_class_unloading()) {
1992 // Disarm nmethods that armed for concurrent mark. On normal cycle, it would
1993 // be disarmed while conc-roots phase is running.
1994 // TODO: Call op_conc_roots() here instead
1995 ShenandoahCodeRoots::disarm_nmethods();
1996 }
1997
1998 op_cleanup_early();
1999
2000 case _degenerated_evac:
2001 // If heuristics thinks we should do the cycle, this flag would be set,
2002 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
2003 if (is_evacuation_in_progress()) {
2004
2005 // Degeneration under oom-evac protocol might have left some objects in
2006 // collection set un-evacuated. Restart evacuation from the beginning to
2007 // capture all objects. For all the objects that are already evacuated,
2008 // it would be a simple check, which is supposed to be fast. This is also
2009 // safe to do even without degeneration, as CSet iterator is at beginning
2010 // in preparation for evacuation anyway.
2011 //
2012 // Before doing that, we need to make sure we never had any cset-pinned
2013 // regions. This may happen if allocation failure happened when evacuating
2014 // the about-to-be-pinned object, oom-evac protocol left the object in
2015 // the collection set, and then the pin reached the cset region. If we continue
2016 // the cycle here, we would trash the cset and alive objects in it. To avoid
2017 // it, we fail degeneration right away and slide into Full GC to recover.
2018
2019 {
2020 sync_pinned_region_status();
2021 collection_set()->clear_current_index();
2022
2023 ShenandoahHeapRegion* r;
2024 while ((r = collection_set()->next()) != NULL) {
2025 if (r->is_pinned()) {
2026 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
2027 op_degenerated_fail();
2028 return;
2029 }
2030 }
2031
2032 collection_set()->clear_current_index();
2033 }
2034
2035 op_stw_evac();
2036 if (cancelled_gc()) {
2037 op_degenerated_fail();
2038 return;
2039 }
2040 }
2041
2042 // If heuristics thinks we should do the cycle, this flag would be set,
2043 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
2044 if (has_forwarded_objects()) {
2045 op_init_updaterefs();
2046 if (cancelled_gc()) {
2047 op_degenerated_fail();
2048 return;
2049 }
2050 }
2051
2052 case _degenerated_updaterefs:
2053 if (has_forwarded_objects()) {
2054 op_final_updaterefs();
2055 if (cancelled_gc()) {
2056 op_degenerated_fail();
2057 return;
2058 }
2059 }
2060
2061 op_cleanup_complete();
2062 break;
2063
2064 default:
2065 ShouldNotReachHere();
2066 }
2067
2068 if (ShenandoahVerify) {
2069 verifier()->verify_after_degenerated();
2070 }
2071
2072 if (VerifyAfterGC) {
2073 Universe::verify();
2074 }
2075
2076 metrics.snap_after();
2077
2078 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
2079 // because that probably means the heap is overloaded and/or fragmented.
2080 if (!metrics.is_good_progress()) {
2081 _progress_last_gc.unset();
2082 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
2083 op_degenerated_futile();
2084 } else {
2085 _progress_last_gc.set();
2086 }
2087 }
2088
2089 void ShenandoahHeap::op_degenerated_fail() {
2090 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
2091 shenandoah_policy()->record_degenerated_upgrade_to_full();
2092 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2093 }
2094
2095 void ShenandoahHeap::op_degenerated_futile() {
2096 shenandoah_policy()->record_degenerated_upgrade_to_full();
2097 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
2098 }
2099
2100 void ShenandoahHeap::force_satb_flush_all_threads() {
2101 if (!is_concurrent_mark_in_progress()) {
2102 // No need to flush SATBs
2103 return;
2104 }
2105
2106 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2107 ShenandoahThreadLocalData::set_force_satb_flush(t, true);
2108 }
2109 // The threads are not "acquiring" their thread-local data, but it does not
2110 // hurt to "release" the updates here anyway.
2111 OrderAccess::fence();
2112 }
2113
2114 void ShenandoahHeap::set_gc_state_all_threads(char state) {
2115 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
2116 ShenandoahThreadLocalData::set_gc_state(t, state);
2117 }
2118 }
2119
2120 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
2121 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
2122 _gc_state.set_cond(mask, value);
2123 set_gc_state_all_threads(_gc_state.raw_value());
2124 }
2125
2126 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
2127 if (has_forwarded_objects()) {
2128 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
2129 } else {
2130 set_gc_state_mask(MARKING, in_progress);
2131 }
2132 ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
2133 }
2134
2135 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
2136 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
2137 set_gc_state_mask(EVACUATION, in_progress);
2138 }
2139
2140 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
2141 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
2142 if (in_progress) {
2143 _concurrent_strong_root_in_progress.set();
2144 } else {
2145 _concurrent_strong_root_in_progress.unset();
2146 }
2147 }
2148
2149 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool in_progress) {
2150 assert(ShenandoahConcurrentRoots::can_do_concurrent_roots(), "Why set the flag?");
2151 if (in_progress) {
2152 _concurrent_weak_root_in_progress.set();
2153 } else {
2154 _concurrent_weak_root_in_progress.unset();
2155 }
2156 }
2157
2158 void ShenandoahHeap::ref_processing_init() {
2159 assert(_max_workers > 0, "Sanity");
2160
2161 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
2162 bool mt_discovery = _max_workers > 1;
2163
2164 _ref_processor =
2165 new ReferenceProcessor(&_subject_to_discovery, // is_subject_to_discovery
2166 mt_processing, // MT processing
2167 _max_workers, // Degree of MT processing
2168 mt_discovery, // MT discovery
2169 _max_workers, // Degree of MT discovery
2170 false, // Reference discovery is not atomic
2171 NULL, // No closure, should be installed before use
2172 true); // Scale worker threads
2173
2174 log_info(gc, init)("Reference processing: %s discovery, %s processing",
2175 mt_discovery ? "parallel" : "serial",
2176 mt_processing ? "parallel" : "serial");
2177
2178 shenandoah_assert_rp_isalive_not_installed();
2179 }
2180
2181 GCTracer* ShenandoahHeap::tracer() {
2182 return shenandoah_policy()->tracer();
2183 }
2184
2185 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
2186 return _free_set->used();
2187 }
2188
2189 bool ShenandoahHeap::try_cancel_gc() {
2190 while (true) {
2191 jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
2192 if (prev == CANCELLABLE) return true;
2193 else if (prev == CANCELLED) return false;
2194 assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
2195 assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
2196 if (Thread::current()->is_Java_thread()) {
2197 // We need to provide a safepoint here, otherwise we might
2198 // spin forever if a SP is pending.
2199 ThreadBlockInVM sp(JavaThread::current());
2200 SpinPause();
2201 }
2202 }
2203 }
2204
2205 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
2206 if (try_cancel_gc()) {
2207 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
2208 log_info(gc)("%s", msg.buffer());
2209 Events::log(Thread::current(), "%s", msg.buffer());
2210 }
2211 }
2212
2213 uint ShenandoahHeap::max_workers() {
2214 return _max_workers;
2215 }
2216
2217 void ShenandoahHeap::stop() {
2218 // The shutdown sequence should be able to terminate when GC is running.
2219
2220 // Step 0. Notify policy to disable event recording.
2221 _shenandoah_policy->record_shutdown();
2222
2223 // Step 1. Notify control thread that we are in shutdown.
2224 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
2225 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
2226 control_thread()->prepare_for_graceful_shutdown();
2227
2228 // Step 2. Notify GC workers that we are cancelling GC.
2229 cancel_gc(GCCause::_shenandoah_stop_vm);
2230
2231 // Step 3. Wait until GC worker exits normally.
2232 control_thread()->stop();
2233
2234 // Step 4. Stop String Dedup thread if it is active
2235 if (ShenandoahStringDedup::is_enabled()) {
2236 ShenandoahStringDedup::stop();
2237 }
2238 }
2239
2240 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
2241 if (!unload_classes()) return;
2242
2243 // Unload classes and purge SystemDictionary.
2244 {
2245 ShenandoahGCPhase phase(full_gc ?
2246 ShenandoahPhaseTimings::full_gc_purge_class_unload :
2247 ShenandoahPhaseTimings::purge_class_unload);
2248 bool purged_class = SystemDictionary::do_unloading(gc_timer());
2249
2250 ShenandoahIsAliveSelector is_alive;
2251 uint num_workers = _workers->active_workers();
2252 ShenandoahClassUnloadingTask unlink_task(is_alive.is_alive_closure(), num_workers, purged_class);
2253 _workers->run_task(&unlink_task);
2254 }
2255
2256 {
2257 ShenandoahGCPhase phase(full_gc ?
2258 ShenandoahPhaseTimings::full_gc_purge_cldg :
2259 ShenandoahPhaseTimings::purge_cldg);
2260 ClassLoaderDataGraph::purge();
2261 }
2262 // Resize and verify metaspace
2263 MetaspaceGC::compute_new_size();
2264 MetaspaceUtils::verify_metrics();
2265 }
2266
2267 // Weak roots are either pre-evacuated (final mark) or updated (final updaterefs),
2268 // so they should not have forwarded oops.
2269 // However, we do need to "null" dead oops in the roots, if can not be done
2270 // in concurrent cycles.
2271 void ShenandoahHeap::stw_process_weak_roots(bool full_gc) {
2272 ShenandoahGCPhase root_phase(full_gc ?
2273 ShenandoahPhaseTimings::full_gc_purge :
2274 ShenandoahPhaseTimings::purge);
2275 uint num_workers = _workers->active_workers();
2276 ShenandoahPhaseTimings::Phase timing_phase = full_gc ?
2277 ShenandoahPhaseTimings::full_gc_purge_weak_par :
2278 ShenandoahPhaseTimings::purge_weak_par;
2279 ShenandoahGCPhase phase(timing_phase);
2280 ShenandoahGCWorkerPhase worker_phase(timing_phase);
2281
2282 // Cleanup weak roots
2283 if (has_forwarded_objects()) {
2284 ShenandoahForwardedIsAliveClosure is_alive;
2285 ShenandoahUpdateRefsClosure keep_alive;
2286 ShenandoahParallelWeakRootsCleaningTask<ShenandoahForwardedIsAliveClosure, ShenandoahUpdateRefsClosure>
2287 cleaning_task(timing_phase, &is_alive, &keep_alive, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2288 _workers->run_task(&cleaning_task);
2289 } else {
2290 ShenandoahIsAliveClosure is_alive;
2291 #ifdef ASSERT
2292 ShenandoahAssertNotForwardedClosure verify_cl;
2293 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, ShenandoahAssertNotForwardedClosure>
2294 cleaning_task(timing_phase, &is_alive, &verify_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2295 #else
2296 ShenandoahParallelWeakRootsCleaningTask<ShenandoahIsAliveClosure, DoNothingClosure>
2297 cleaning_task(timing_phase, &is_alive, &do_nothing_cl, num_workers, !ShenandoahConcurrentRoots::should_do_concurrent_class_unloading());
2298 #endif
2299 _workers->run_task(&cleaning_task);
2300 }
2301 }
2302
2303 void ShenandoahHeap::parallel_cleaning(bool full_gc) {
2304 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2305 stw_process_weak_roots(full_gc);
2306 if (!ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2307 stw_unload_classes(full_gc);
2308 }
2309 }
2310
2311 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2312 set_gc_state_mask(HAS_FORWARDED, cond);
2313 }
2314
2315 void ShenandoahHeap::set_process_references(bool pr) {
2316 _process_references.set_cond(pr);
2317 }
2318
2319 void ShenandoahHeap::set_unload_classes(bool uc) {
2320 _unload_classes.set_cond(uc);
2321 }
2322
2323 bool ShenandoahHeap::process_references() const {
2324 return _process_references.is_set();
2325 }
2326
2327 bool ShenandoahHeap::unload_classes() const {
2328 return _unload_classes.is_set();
2329 }
2330
2331 address ShenandoahHeap::in_cset_fast_test_addr() {
2332 ShenandoahHeap* heap = ShenandoahHeap::heap();
2333 assert(heap->collection_set() != NULL, "Sanity");
2334 return (address) heap->collection_set()->biased_map_address();
2335 }
2336
2337 address ShenandoahHeap::cancelled_gc_addr() {
2338 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
2339 }
2340
2341 address ShenandoahHeap::gc_state_addr() {
2342 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2343 }
2344
2345 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
2346 return Atomic::load_acquire(&_bytes_allocated_since_gc_start);
2347 }
2348
2349 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2350 Atomic::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
2351 }
2352
2353 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2354 _degenerated_gc_in_progress.set_cond(in_progress);
2355 }
2356
2357 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2358 _full_gc_in_progress.set_cond(in_progress);
2359 }
2360
2361 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2362 assert (is_full_gc_in_progress(), "should be");
2363 _full_gc_move_in_progress.set_cond(in_progress);
2364 }
2365
2366 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2367 set_gc_state_mask(UPDATEREFS, in_progress);
2368 }
2369
2370 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2371 ShenandoahCodeRoots::register_nmethod(nm);
2372 }
2373
2374 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2375 ShenandoahCodeRoots::unregister_nmethod(nm);
2376 }
2377
2378 void ShenandoahHeap::flush_nmethod(nmethod* nm) {
2379 ShenandoahCodeRoots::flush_nmethod(nm);
2380 }
2381
2382 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2383 heap_region_containing(o)->record_pin();
2384 return o;
2385 }
2386
2387 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2388 heap_region_containing(o)->record_unpin();
2389 }
2390
2391 void ShenandoahHeap::sync_pinned_region_status() {
2392 ShenandoahHeapLocker locker(lock());
2393
2394 for (size_t i = 0; i < num_regions(); i++) {
2395 ShenandoahHeapRegion *r = get_region(i);
2396 if (r->is_active()) {
2397 if (r->is_pinned()) {
2398 if (r->pin_count() == 0) {
2399 r->make_unpinned();
2400 }
2401 } else {
2402 if (r->pin_count() > 0) {
2403 r->make_pinned();
2404 }
2405 }
2406 }
2407 }
2408
2409 assert_pinned_region_status();
2410 }
2411
2412 #ifdef ASSERT
2413 void ShenandoahHeap::assert_pinned_region_status() {
2414 for (size_t i = 0; i < num_regions(); i++) {
2415 ShenandoahHeapRegion* r = get_region(i);
2416 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2417 "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2418 }
2419 }
2420 #endif
2421
2422 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
2423 return _gc_timer;
2424 }
2425
2426 void ShenandoahHeap::prepare_concurrent_roots() {
2427 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2428 if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
2429 set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
2430 set_concurrent_weak_root_in_progress(true);
2431 }
2432 }
2433
2434 void ShenandoahHeap::prepare_concurrent_unloading() {
2435 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2436 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2437 _unloader.prepare();
2438 }
2439 }
2440
2441 void ShenandoahHeap::finish_concurrent_unloading() {
2442 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2443 if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
2444 _unloader.finish();
2445 }
2446 }
2447
2448 #ifdef ASSERT
2449 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2450 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2451
2452 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2453 if (UseDynamicNumberOfGCThreads) {
2454 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2455 } else {
2456 // Use ParallelGCThreads inside safepoints
2457 assert(nworkers == ParallelGCThreads, "Use ParallelGCThreads within safepoints");
2458 }
2459 } else {
2460 if (UseDynamicNumberOfGCThreads) {
2461 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2462 } else {
2463 // Use ConcGCThreads outside safepoints
2464 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2465 }
2466 }
2467 }
2468 #endif
2469
2470 ShenandoahVerifier* ShenandoahHeap::verifier() {
2471 guarantee(ShenandoahVerify, "Should be enabled");
2472 assert (_verifier != NULL, "sanity");
2473 return _verifier;
2474 }
2475
2476 template<class T>
2477 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2478 private:
2479 T cl;
2480 ShenandoahHeap* _heap;
2481 ShenandoahRegionIterator* _regions;
2482 bool _concurrent;
2483 public:
2484 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2485 AbstractGangTask("Concurrent Update References Task"),
2486 cl(T()),
2487 _heap(ShenandoahHeap::heap()),
2488 _regions(regions),
2489 _concurrent(concurrent) {
2490 }
2491
2492 void work(uint worker_id) {
2493 if (_concurrent) {
2494 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2495 ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2496 do_work();
2497 } else {
2498 ShenandoahParallelWorkerSession worker_session(worker_id);
2499 do_work();
2500 }
2501 }
2502
2503 private:
2504 void do_work() {
2505 ShenandoahHeapRegion* r = _regions->next();
2506 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2507 while (r != NULL) {
2508 HeapWord* update_watermark = r->get_update_watermark();
2509 assert (update_watermark >= r->bottom(), "sanity");
2510 if (r->is_active() && !r->is_cset()) {
2511 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2512 }
2513 if (ShenandoahPacing) {
2514 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2515 }
2516 if (_heap->check_cancelled_gc_and_yield(_concurrent)) {
2517 return;
2518 }
2519 r = _regions->next();
2520 }
2521 }
2522 };
2523
2524 void ShenandoahHeap::update_heap_references(bool concurrent) {
2525 ShenandoahUpdateHeapRefsTask<ShenandoahUpdateHeapRefsClosure> task(&_update_refs_iterator, concurrent);
2526 workers()->run_task(&task);
2527 }
2528
2529 void ShenandoahHeap::op_init_updaterefs() {
2530 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2531
2532 set_evacuation_in_progress(false);
2533
2534 {
2535 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_retire_gclabs);
2536 retire_and_reset_gclabs();
2537 }
2538
2539 if (ShenandoahVerify) {
2540 if (!is_degenerated_gc_in_progress()) {
2541 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2542 }
2543 verifier()->verify_before_updaterefs();
2544 }
2545
2546 set_update_refs_in_progress(true);
2547
2548 _update_refs_iterator.reset();
2549
2550 if (ShenandoahPacing) {
2551 pacer()->setup_for_updaterefs();
2552 }
2553 }
2554
2555 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2556 private:
2557 ShenandoahHeapLock* const _lock;
2558
2559 public:
2560 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2561
2562 void heap_region_do(ShenandoahHeapRegion* r) {
2563 // Drop unnecessary "pinned" state from regions that does not have CP marks
2564 // anymore, as this would allow trashing them.
2565
2566 if (r->is_active()) {
2567 if (r->is_pinned()) {
2568 if (r->pin_count() == 0) {
2569 ShenandoahHeapLocker locker(_lock);
2570 r->make_unpinned();
2571 }
2572 } else {
2573 if (r->pin_count() > 0) {
2574 ShenandoahHeapLocker locker(_lock);
2575 r->make_pinned();
2576 }
2577 }
2578 }
2579 }
2580
2581 bool is_thread_safe() { return true; }
2582 };
2583
2584 void ShenandoahHeap::op_final_updaterefs() {
2585 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2586
2587 finish_concurrent_unloading();
2588
2589 // Check if there is left-over work, and finish it
2590 if (_update_refs_iterator.has_next()) {
2591 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2592
2593 // Finish updating references where we left off.
2594 clear_cancelled_gc();
2595 update_heap_references(false);
2596 }
2597
2598 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2599 // everything. On degenerated paths, cancelled gc would not be set anyway.
2600 if (cancelled_gc()) {
2601 clear_cancelled_gc();
2602 }
2603 assert(!cancelled_gc(), "Should have been done right before");
2604
2605 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2606 verifier()->verify_roots_in_to_space_except(ShenandoahRootVerifier::ThreadRoots);
2607 }
2608
2609 if (is_degenerated_gc_in_progress()) {
2610 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2611 } else {
2612 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2613 }
2614
2615 // Has to be done before cset is clear
2616 if (ShenandoahVerify) {
2617 verifier()->verify_roots_in_to_space();
2618 }
2619
2620 {
2621 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_update_region_states);
2622 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2623 parallel_heap_region_iterate(&cl);
2624
2625 assert_pinned_region_status();
2626 }
2627
2628 {
2629 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2630 trash_cset_regions();
2631 }
2632
2633 set_has_forwarded_objects(false);
2634 set_update_refs_in_progress(false);
2635
2636 if (ShenandoahVerify) {
2637 verifier()->verify_after_updaterefs();
2638 }
2639
2640 if (VerifyAfterGC) {
2641 Universe::verify();
2642 }
2643
2644 {
2645 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_rebuild_freeset);
2646 ShenandoahHeapLocker locker(lock());
2647 _free_set->rebuild();
2648 }
2649 }
2650
2651 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2652 print_on(st);
2653 print_heap_regions_on(st);
2654 }
2655
2656 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2657 size_t slice = r->index() / _bitmap_regions_per_slice;
2658
2659 size_t regions_from = _bitmap_regions_per_slice * slice;
2660 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2661 for (size_t g = regions_from; g < regions_to; g++) {
2662 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2663 if (skip_self && g == r->index()) continue;
2664 if (get_region(g)->is_committed()) {
2665 return true;
2666 }
2667 }
2668 return false;
2669 }
2670
2671 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2672 shenandoah_assert_heaplocked();
2673
2674 // Bitmaps in special regions do not need commits
2675 if (_bitmap_region_special) {
2676 return true;
2677 }
2678
2679 if (is_bitmap_slice_committed(r, true)) {
2680 // Some other region from the group is already committed, meaning the bitmap
2681 // slice is already committed, we exit right away.
2682 return true;
2683 }
2684
2685 // Commit the bitmap slice:
2686 size_t slice = r->index() / _bitmap_regions_per_slice;
2687 size_t off = _bitmap_bytes_per_slice * slice;
2688 size_t len = _bitmap_bytes_per_slice;
2689 if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) {
2690 return false;
2691 }
2692 return true;
2693 }
2694
2695 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2696 shenandoah_assert_heaplocked();
2697
2698 // Bitmaps in special regions do not need uncommits
2699 if (_bitmap_region_special) {
2700 return true;
2701 }
2702
2703 if (is_bitmap_slice_committed(r, true)) {
2704 // Some other region from the group is still committed, meaning the bitmap
2705 // slice is should stay committed, exit right away.
2706 return true;
2707 }
2708
2709 // Uncommit the bitmap slice:
2710 size_t slice = r->index() / _bitmap_regions_per_slice;
2711 size_t off = _bitmap_bytes_per_slice * slice;
2712 size_t len = _bitmap_bytes_per_slice;
2713 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2714 return false;
2715 }
2716 return true;
2717 }
2718
2719 void ShenandoahHeap::safepoint_synchronize_begin() {
2720 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2721 SuspendibleThreadSet::synchronize();
2722 }
2723 }
2724
2725 void ShenandoahHeap::safepoint_synchronize_end() {
2726 if (ShenandoahSuspendibleWorkers || UseStringDeduplication) {
2727 SuspendibleThreadSet::desynchronize();
2728 }
2729 }
2730
2731 void ShenandoahHeap::vmop_entry_init_mark() {
2732 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2733 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::init_mark_gross);
2734
2735 try_inject_alloc_failure();
2736 VM_ShenandoahInitMark op;
2737 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2738 }
2739
2740 void ShenandoahHeap::vmop_entry_final_mark() {
2741 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2742 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_mark_gross);
2743
2744 try_inject_alloc_failure();
2745 VM_ShenandoahFinalMarkStartEvac op;
2746 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2747 }
2748
2749 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2750 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2751 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::init_update_refs_gross);
2752
2753 try_inject_alloc_failure();
2754 VM_ShenandoahInitUpdateRefs op;
2755 VMThread::execute(&op);
2756 }
2757
2758 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2759 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2760 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::final_update_refs_gross);
2761
2762 try_inject_alloc_failure();
2763 VM_ShenandoahFinalUpdateRefs op;
2764 VMThread::execute(&op);
2765 }
2766
2767 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2768 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2769 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::full_gc_gross);
2770
2771 try_inject_alloc_failure();
2772 VM_ShenandoahFullGC op(cause);
2773 VMThread::execute(&op);
2774 }
2775
2776 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2777 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2778 ShenandoahTimingsTracker timing(ShenandoahPhaseTimings::degen_gc_gross);
2779
2780 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2781 VMThread::execute(°enerated_gc);
2782 }
2783
2784 void ShenandoahHeap::entry_init_mark() {
2785 const char* msg = init_mark_event_message();
2786 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::init_mark);
2787 EventMark em("%s", msg);
2788
2789 ShenandoahWorkerScope scope(workers(),
2790 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2791 "init marking");
2792
2793 op_init_mark();
2794 }
2795
2796 void ShenandoahHeap::entry_final_mark() {
2797 const char* msg = final_mark_event_message();
2798 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_mark);
2799 EventMark em("%s", msg);
2800
2801 ShenandoahWorkerScope scope(workers(),
2802 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2803 "final marking");
2804
2805 op_final_mark();
2806 }
2807
2808 void ShenandoahHeap::entry_init_updaterefs() {
2809 static const char* msg = "Pause Init Update Refs";
2810 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::init_update_refs);
2811 EventMark em("%s", msg);
2812
2813 // No workers used in this phase, no setup required
2814
2815 op_init_updaterefs();
2816 }
2817
2818 void ShenandoahHeap::entry_final_updaterefs() {
2819 static const char* msg = "Pause Final Update Refs";
2820 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::final_update_refs);
2821 EventMark em("%s", msg);
2822
2823 ShenandoahWorkerScope scope(workers(),
2824 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2825 "final reference update");
2826
2827 op_final_updaterefs();
2828 }
2829
2830 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2831 static const char* msg = "Pause Full";
2832 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::full_gc, true /* log_heap_usage */);
2833 EventMark em("%s", msg);
2834
2835 ShenandoahWorkerScope scope(workers(),
2836 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2837 "full gc");
2838
2839 op_full(cause);
2840 }
2841
2842 void ShenandoahHeap::entry_degenerated(int point) {
2843 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2844 const char* msg = degen_event_message(dpoint);
2845 ShenandoahPausePhase gc_phase(msg, ShenandoahPhaseTimings::degen_gc, true /* log_heap_usage */);
2846 EventMark em("%s", msg);
2847
2848 ShenandoahWorkerScope scope(workers(),
2849 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2850 "stw degenerated gc");
2851
2852 set_degenerated_gc_in_progress(true);
2853 op_degenerated(dpoint);
2854 set_degenerated_gc_in_progress(false);
2855 }
2856
2857 void ShenandoahHeap::entry_mark() {
2858 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2859
2860 const char* msg = conc_mark_event_message();
2861 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_mark);
2862 EventMark em("%s", msg);
2863
2864 ShenandoahWorkerScope scope(workers(),
2865 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2866 "concurrent marking");
2867
2868 try_inject_alloc_failure();
2869 op_mark();
2870 }
2871
2872 void ShenandoahHeap::entry_evac() {
2873 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2874
2875 static const char* msg = "Concurrent evacuation";
2876 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_evac);
2877 EventMark em("%s", msg);
2878
2879 ShenandoahWorkerScope scope(workers(),
2880 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2881 "concurrent evacuation");
2882
2883 try_inject_alloc_failure();
2884 op_conc_evac();
2885 }
2886
2887 void ShenandoahHeap::entry_updaterefs() {
2888 static const char* msg = "Concurrent update references";
2889 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_update_refs);
2890 EventMark em("%s", msg);
2891
2892 ShenandoahWorkerScope scope(workers(),
2893 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2894 "concurrent reference update");
2895
2896 try_inject_alloc_failure();
2897 op_updaterefs();
2898 }
2899
2900 void ShenandoahHeap::entry_weak_roots() {
2901 static const char* msg = "Concurrent weak roots";
2902 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_weak_roots);
2903 EventMark em("%s", msg);
2904
2905 ShenandoahWorkerScope scope(workers(),
2906 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2907 "concurrent weak root");
2908
2909 try_inject_alloc_failure();
2910 op_weak_roots();
2911 }
2912
2913 void ShenandoahHeap::entry_class_unloading() {
2914 static const char* msg = "Concurrent class unloading";
2915 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_class_unload);
2916 EventMark em("%s", msg);
2917
2918 ShenandoahWorkerScope scope(workers(),
2919 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2920 "concurrent class unloading");
2921
2922 try_inject_alloc_failure();
2923 op_class_unloading();
2924 }
2925
2926 void ShenandoahHeap::entry_strong_roots() {
2927 static const char* msg = "Concurrent strong roots";
2928 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_strong_roots);
2929 EventMark em("%s", msg);
2930
2931 ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_strong_roots);
2932
2933 ShenandoahWorkerScope scope(workers(),
2934 ShenandoahWorkerPolicy::calc_workers_for_conc_root_processing(),
2935 "concurrent strong root");
2936
2937 try_inject_alloc_failure();
2938 op_strong_roots();
2939 }
2940
2941 void ShenandoahHeap::entry_cleanup_early() {
2942 static const char* msg = "Concurrent cleanup";
2943 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_cleanup_early, true /* log_heap_usage */);
2944 EventMark em("%s", msg);
2945
2946 // This phase does not use workers, no need for setup
2947
2948 try_inject_alloc_failure();
2949 op_cleanup_early();
2950 }
2951
2952 void ShenandoahHeap::entry_cleanup_complete() {
2953 static const char* msg = "Concurrent cleanup";
2954 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_cleanup_complete, true /* log_heap_usage */);
2955 EventMark em("%s", msg);
2956
2957 // This phase does not use workers, no need for setup
2958
2959 try_inject_alloc_failure();
2960 op_cleanup_complete();
2961 }
2962
2963 void ShenandoahHeap::entry_reset() {
2964 static const char* msg = "Concurrent reset";
2965 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_reset);
2966 EventMark em("%s", msg);
2967
2968 ShenandoahWorkerScope scope(workers(),
2969 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2970 "concurrent reset");
2971
2972 try_inject_alloc_failure();
2973 op_reset();
2974 }
2975
2976 void ShenandoahHeap::entry_preclean() {
2977 if (ShenandoahPreclean && process_references()) {
2978 static const char* msg = "Concurrent precleaning";
2979 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_preclean);
2980 EventMark em("%s", msg);
2981
2982 ShenandoahWorkerScope scope(workers(),
2983 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2984 "concurrent preclean",
2985 /* check_workers = */ false);
2986
2987 try_inject_alloc_failure();
2988 op_preclean();
2989 }
2990 }
2991
2992 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2993 static const char *msg = "Concurrent uncommit";
2994 ShenandoahConcurrentPhase gc_phase(msg, ShenandoahPhaseTimings::conc_uncommit, true /* log_heap_usage */);
2995 EventMark em("%s", msg);
2996
2997 op_uncommit(shrink_before);
2998 }
2999
3000 void ShenandoahHeap::try_inject_alloc_failure() {
3001 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
3002 _inject_alloc_failure.set();
3003 os::naked_short_sleep(1);
3004 if (cancelled_gc()) {
3005 log_info(gc)("Allocation failure was successfully injected");
3006 }
3007 }
3008 }
3009
3010 bool ShenandoahHeap::should_inject_alloc_failure() {
3011 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
3012 }
3013
3014 void ShenandoahHeap::initialize_serviceability() {
3015 _memory_pool = new ShenandoahMemoryPool(this);
3016 _cycle_memory_manager.add_pool(_memory_pool);
3017 _stw_memory_manager.add_pool(_memory_pool);
3018 }
3019
3020 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
3021 GrowableArray<GCMemoryManager*> memory_managers(2);
3022 memory_managers.append(&_cycle_memory_manager);
3023 memory_managers.append(&_stw_memory_manager);
3024 return memory_managers;
3025 }
3026
3027 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
3028 GrowableArray<MemoryPool*> memory_pools(1);
3029 memory_pools.append(_memory_pool);
3030 return memory_pools;
3031 }
3032
3033 MemoryUsage ShenandoahHeap::memory_usage() {
3034 return _memory_pool->get_memory_usage();
3035 }
3036
3037 void ShenandoahHeap::enter_evacuation() {
3038 _oom_evac_handler.enter_evacuation();
3039 }
3040
3041 void ShenandoahHeap::leave_evacuation() {
3042 _oom_evac_handler.leave_evacuation();
3043 }
3044
3045 ShenandoahRegionIterator::ShenandoahRegionIterator() :
3046 _heap(ShenandoahHeap::heap()),
3047 _index(0) {}
3048
3049 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
3050 _heap(heap),
3051 _index(0) {}
3052
3053 void ShenandoahRegionIterator::reset() {
3054 _index = 0;
3055 }
3056
3057 bool ShenandoahRegionIterator::has_next() const {
3058 return _index < _heap->num_regions();
3059 }
3060
3061 char ShenandoahHeap::gc_state() const {
3062 return _gc_state.raw_value();
3063 }
3064
3065 void ShenandoahHeap::deduplicate_string(oop str) {
3066 assert(java_lang_String::is_instance(str), "invariant");
3067
3068 if (ShenandoahStringDedup::is_enabled()) {
3069 ShenandoahStringDedup::deduplicate(str);
3070 }
3071 }
3072
3073 const char* ShenandoahHeap::init_mark_event_message() const {
3074 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3075
3076 bool proc_refs = process_references();
3077 bool unload_cls = unload_classes();
3078
3079 if (proc_refs && unload_cls) {
3080 return "Pause Init Mark (process weakrefs) (unload classes)";
3081 } else if (proc_refs) {
3082 return "Pause Init Mark (process weakrefs)";
3083 } else if (unload_cls) {
3084 return "Pause Init Mark (unload classes)";
3085 } else {
3086 return "Pause Init Mark";
3087 }
3088 }
3089
3090 const char* ShenandoahHeap::final_mark_event_message() const {
3091 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3092
3093 bool proc_refs = process_references();
3094 bool unload_cls = unload_classes();
3095
3096 if (proc_refs && unload_cls) {
3097 return "Pause Final Mark (process weakrefs) (unload classes)";
3098 } else if (proc_refs) {
3099 return "Pause Final Mark (process weakrefs)";
3100 } else if (unload_cls) {
3101 return "Pause Final Mark (unload classes)";
3102 } else {
3103 return "Pause Final Mark";
3104 }
3105 }
3106
3107 const char* ShenandoahHeap::conc_mark_event_message() const {
3108 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
3109
3110 bool proc_refs = process_references();
3111 bool unload_cls = unload_classes();
3112
3113 if (proc_refs && unload_cls) {
3114 return "Concurrent marking (process weakrefs) (unload classes)";
3115 } else if (proc_refs) {
3116 return "Concurrent marking (process weakrefs)";
3117 } else if (unload_cls) {
3118 return "Concurrent marking (unload classes)";
3119 } else {
3120 return "Concurrent marking";
3121 }
3122 }
3123
3124 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
3125 switch (point) {
3126 case _degenerated_unset:
3127 return "Pause Degenerated GC (<UNSET>)";
3128 case _degenerated_outside_cycle:
3129 return "Pause Degenerated GC (Outside of Cycle)";
3130 case _degenerated_mark:
3131 return "Pause Degenerated GC (Mark)";
3132 case _degenerated_evac:
3133 return "Pause Degenerated GC (Evacuation)";
3134 case _degenerated_updaterefs:
3135 return "Pause Degenerated GC (Update Refs)";
3136 default:
3137 ShouldNotReachHere();
3138 return "ERROR";
3139 }
3140 }
3141
3142 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
3143 #ifdef ASSERT
3144 assert(_liveness_cache != NULL, "sanity");
3145 assert(worker_id < _max_workers, "sanity");
3146 for (uint i = 0; i < num_regions(); i++) {
3147 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
3148 }
3149 #endif
3150 return _liveness_cache[worker_id];
3151 }
3152
3153 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
3154 assert(worker_id < _max_workers, "sanity");
3155 assert(_liveness_cache != NULL, "sanity");
3156 ShenandoahLiveData* ld = _liveness_cache[worker_id];
3157 for (uint i = 0; i < num_regions(); i++) {
3158 ShenandoahLiveData live = ld[i];
3159 if (live > 0) {
3160 ShenandoahHeapRegion* r = get_region(i);
3161 r->increase_live_data_gc_words(live);
3162 ld[i] = 0;
3163 }
3164 }
3165 }