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