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