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