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