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