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_implementation/shared/gcTimer.hpp"
28 #include "gc_implementation/shenandoah/shenandoahGCTraceTime.hpp"
29 #include "gc_implementation/shared/parallelCleaning.hpp"
30
31 #include "gc_implementation/shenandoah/shenandoahAllocTracker.hpp"
32 #include "gc_implementation/shenandoah/shenandoahBarrierSet.hpp"
33 #include "gc_implementation/shenandoah/shenandoahClosures.inline.hpp"
34 #include "gc_implementation/shenandoah/shenandoahCollectionSet.hpp"
35 #include "gc_implementation/shenandoah/shenandoahCollectorPolicy.hpp"
36 #include "gc_implementation/shenandoah/shenandoahConcurrentMark.inline.hpp"
37 #include "gc_implementation/shenandoah/shenandoahControlThread.hpp"
38 #include "gc_implementation/shenandoah/shenandoahFreeSet.hpp"
39 #include "gc_implementation/shenandoah/shenandoahPhaseTimings.hpp"
40 #include "gc_implementation/shenandoah/shenandoahHeap.inline.hpp"
41 #include "gc_implementation/shenandoah/shenandoahHeapRegion.hpp"
42 #include "gc_implementation/shenandoah/shenandoahHeapRegionSet.hpp"
43 #include "gc_implementation/shenandoah/shenandoahHeuristics.hpp"
44 #include "gc_implementation/shenandoah/shenandoahMarkCompact.hpp"
45 #include "gc_implementation/shenandoah/shenandoahMarkingContext.inline.hpp"
46 #include "gc_implementation/shenandoah/shenandoahMonitoringSupport.hpp"
47 #include "gc_implementation/shenandoah/shenandoahMetrics.hpp"
48 #include "gc_implementation/shenandoah/shenandoahNormalMode.hpp"
49 #include "gc_implementation/shenandoah/shenandoahOopClosures.inline.hpp"
50 #include "gc_implementation/shenandoah/shenandoahPacer.inline.hpp"
51 #include "gc_implementation/shenandoah/shenandoahPassiveMode.hpp"
52 #include "gc_implementation/shenandoah/shenandoahRootProcessor.hpp"
53 #include "gc_implementation/shenandoah/shenandoahTaskqueue.hpp"
54 #include "gc_implementation/shenandoah/shenandoahTraversalMode.hpp"
55 #include "gc_implementation/shenandoah/shenandoahUtils.hpp"
56 #include "gc_implementation/shenandoah/shenandoahVerifier.hpp"
57 #include "gc_implementation/shenandoah/shenandoahCodeRoots.hpp"
58 #include "gc_implementation/shenandoah/shenandoahVMOperations.hpp"
59 #include "gc_implementation/shenandoah/shenandoahWorkGroup.hpp"
60 #include "gc_implementation/shenandoah/shenandoahWorkerPolicy.hpp"
61
62 #include "memory/metaspace.hpp"
63 #include "runtime/vmThread.hpp"
64 #include "services/mallocTracker.hpp"
65
66 #ifdef ASSERT
67 template <class T>
68 void ShenandoahAssertToSpaceClosure::do_oop_nv(T* p) {
69 T o = oopDesc::load_heap_oop(p);
70 if (! oopDesc::is_null(o)) {
71 oop obj = oopDesc::decode_heap_oop_not_null(o);
72 shenandoah_assert_not_forwarded(p, obj);
73 }
74 }
75
76 void ShenandoahAssertToSpaceClosure::do_oop(narrowOop* p) { do_oop_nv(p); }
77 void ShenandoahAssertToSpaceClosure::do_oop(oop* p) { do_oop_nv(p); }
78 #endif
79
80 class ShenandoahPretouchHeapTask : public AbstractGangTask {
81 private:
82 ShenandoahRegionIterator _regions;
83 const size_t _page_size;
84 public:
85 ShenandoahPretouchHeapTask(size_t page_size) :
86 AbstractGangTask("Shenandoah Pretouch Heap"),
87 _page_size(page_size) {}
88
89 virtual void work(uint worker_id) {
90 ShenandoahHeapRegion* r = _regions.next();
91 while (r != NULL) {
92 os::pretouch_memory((char*) r->bottom(), (char*) r->end());
93 r = _regions.next();
94 }
95 }
96 };
97
98 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
99 private:
100 ShenandoahRegionIterator _regions;
101 char* _bitmap_base;
102 const size_t _bitmap_size;
103 const size_t _page_size;
104 public:
105 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
106 AbstractGangTask("Shenandoah Pretouch Bitmap"),
107 _bitmap_base(bitmap_base),
108 _bitmap_size(bitmap_size),
109 _page_size(page_size) {}
110
111 virtual void work(uint worker_id) {
112 ShenandoahHeapRegion* r = _regions.next();
113 while (r != NULL) {
114 size_t start = r->region_number() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
115 size_t end = (r->region_number() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
116 assert (end <= _bitmap_size, err_msg("end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size));
117
118 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end);
119
120 r = _regions.next();
121 }
122 }
123 };
124
125 jint ShenandoahHeap::initialize() {
126 CollectedHeap::pre_initialize();
127
128 initialize_heuristics();
129
130 //
131 // Figure out heap sizing
132 //
133
134 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
135 size_t min_byte_size = collector_policy()->min_heap_byte_size();
136 size_t max_byte_size = collector_policy()->max_heap_byte_size();
137 size_t heap_alignment = collector_policy()->heap_alignment();
138
139 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
140
141 if (ShenandoahAlwaysPreTouch) {
142 // Enabled pre-touch means the entire heap is committed right away.
143 init_byte_size = max_byte_size;
144 }
145
146 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
147 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
148
149 _num_regions = ShenandoahHeapRegion::region_count();
150
151 size_t num_committed_regions = init_byte_size / reg_size_bytes;
152 num_committed_regions = MIN2(num_committed_regions, _num_regions);
153 assert(num_committed_regions <= _num_regions, "sanity");
154 _initial_size = num_committed_regions * reg_size_bytes;
155
156 size_t num_min_regions = min_byte_size / reg_size_bytes;
157 num_min_regions = MIN2(num_min_regions, _num_regions);
158 assert(num_min_regions <= _num_regions, "sanity");
159 _minimum_size = num_min_regions * reg_size_bytes;
160
161 _committed = _initial_size;
162
163 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
164 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
165
166 //
167 // Reserve and commit memory for heap
168 //
169
170 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
171 _reserved.set_word_size(0);
172 _reserved.set_start((HeapWord*)heap_rs.base());
173 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
174 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
175 _heap_region_special = heap_rs.special();
176
177 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
178 err_msg("Misaligned heap: " PTR_FORMAT, p2i(base())));
179
180 #if SHENANDOAH_OPTIMIZED_OBJTASK
181 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
182 // Fail if we ever attempt to address more than we can.
183 if ((uintptr_t)(heap_rs.base() + heap_rs.size()) >= ObjArrayChunkedTask::max_addressable()) {
184 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
185 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
186 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
187 p2i(heap_rs.base()), p2i(heap_rs.base() + heap_rs.size()), ObjArrayChunkedTask::max_addressable());
188 vm_exit_during_initialization("Fatal Error", buf);
189 }
190 #endif
191
192 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
193 if (!_heap_region_special) {
194 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
195 "Cannot commit heap memory");
196 }
197
198 //
199 // Reserve and commit memory for bitmap(s)
200 //
201
202 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
203 _bitmap_size = align_size_up(_bitmap_size, bitmap_page_size);
204
205 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
206
207 guarantee(bitmap_bytes_per_region != 0,
208 err_msg("Bitmap bytes per region should not be zero"));
209 guarantee(is_power_of_2(bitmap_bytes_per_region),
210 err_msg("Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region));
211
212 if (bitmap_page_size > bitmap_bytes_per_region) {
213 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
214 _bitmap_bytes_per_slice = bitmap_page_size;
215 } else {
216 _bitmap_regions_per_slice = 1;
217 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
218 }
219
220 guarantee(_bitmap_regions_per_slice >= 1,
221 err_msg("Should have at least one region per slice: " SIZE_FORMAT,
222 _bitmap_regions_per_slice));
223
224 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
225 err_msg("Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
226 _bitmap_bytes_per_slice, bitmap_page_size));
227
228 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
229 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
230 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
231 _bitmap_region_special = bitmap.special();
232
233 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
234 align_size_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
235 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
236 if (!_bitmap_region_special) {
237 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
238 "Cannot commit bitmap memory");
239 }
240
241 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
242
243 if (ShenandoahVerify) {
244 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
245 if (!verify_bitmap.special()) {
246 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
247 "Cannot commit verification bitmap memory");
248 }
249 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
250 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
251 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
252 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
253 }
254
255 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
256 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
257 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
258 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
259 _aux_bitmap_region_special = aux_bitmap.special();
260 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
261
262 //
263 // Create regions and region sets
264 //
265
266 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
267 _free_set = new ShenandoahFreeSet(this, _num_regions);
268 _collection_set = new ShenandoahCollectionSet(this, sh_rs.base(), sh_rs.size());
269
270 {
271 ShenandoahHeapLocker locker(lock());
272
273 size_t size_words = ShenandoahHeapRegion::region_size_words();
274
275 for (size_t i = 0; i < _num_regions; i++) {
276 HeapWord* start = (HeapWord*)sh_rs.base() + size_words * i;
277 bool is_committed = i < num_committed_regions;
278 ShenandoahHeapRegion* r = new ShenandoahHeapRegion(this, start, size_words, i, is_committed);
279
280 _marking_context->initialize_top_at_mark_start(r);
281 _regions[i] = r;
282 assert(!collection_set()->is_in(i), "New region should not be in collection set");
283 }
284
285 // Initialize to complete
286 _marking_context->mark_complete();
287
288 _free_set->rebuild();
289 }
290
291 if (ShenandoahAlwaysPreTouch) {
292 assert(!AlwaysPreTouch, "Should have been overridden");
293
294 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
295 // before initialize() below zeroes it with initializing thread. For any given region,
296 // we touch the region and the corresponding bitmaps from the same thread.
297 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
298
299 size_t pretouch_heap_page_size = heap_page_size;
300 size_t pretouch_bitmap_page_size = bitmap_page_size;
301
302 #ifdef LINUX
303 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
304 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
305 // them into huge one. Therefore, we need to pretouch with smaller pages.
306 if (UseTransparentHugePages) {
307 pretouch_heap_page_size = (size_t)os::vm_page_size();
308 pretouch_bitmap_page_size = (size_t)os::vm_page_size();
309 }
310 #endif
311
312 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
313 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
314
315 log_info(gc, init)("Pretouch bitmap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
316 _num_regions, pretouch_bitmap_page_size);
317 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, pretouch_bitmap_page_size);
318 _workers->run_task(&bcl);
319
320 log_info(gc, init)("Pretouch heap: " SIZE_FORMAT " regions, " SIZE_FORMAT " bytes page",
321 _num_regions, pretouch_heap_page_size);
322 ShenandoahPretouchHeapTask hcl(pretouch_heap_page_size);
323 _workers->run_task(&hcl);
324 }
325
326 //
327 // Initialize the rest of GC subsystems
328 //
329
330 set_barrier_set(new ShenandoahBarrierSet(this));
331
332 _liveness_cache = NEW_C_HEAP_ARRAY(jushort*, _max_workers, mtGC);
333 for (uint worker = 0; worker < _max_workers; worker++) {
334 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(jushort, _num_regions, mtGC);
335 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(jushort));
336 }
337
338 // The call below uses stuff (the SATB* things) that are in G1, but probably
339 // belong into a shared location.
340 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
341 SATB_Q_FL_lock,
342 20 /*G1SATBProcessCompletedThreshold */,
343 Shared_SATB_Q_lock);
344
345 _monitoring_support = new ShenandoahMonitoringSupport(this);
346 _phase_timings = new ShenandoahPhaseTimings();
347 ShenandoahStringDedup::initialize();
348 ShenandoahCodeRoots::initialize();
349
350 if (ShenandoahAllocationTrace) {
351 _alloc_tracker = new ShenandoahAllocTracker();
352 }
353
354 if (ShenandoahPacing) {
355 _pacer = new ShenandoahPacer(this);
356 _pacer->setup_for_idle();
357 } else {
358 _pacer = NULL;
359 }
360
361 _traversal_gc = strcmp(ShenandoahGCMode, "traversal") == 0 ?
362 new ShenandoahTraversalGC(this, _num_regions) :
363 NULL;
364
365 _control_thread = new ShenandoahControlThread();
366
367 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max",
368 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size),
369 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size),
370 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity())
371 );
372
373 return JNI_OK;
374 }
375
376 #ifdef _MSC_VER
377 #pragma warning( push )
378 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
379 #endif
380
381 void ShenandoahHeap::initialize_heuristics() {
382 if (ShenandoahGCMode != NULL) {
383 if (strcmp(ShenandoahGCMode, "traversal") == 0) {
384 _gc_mode = new ShenandoahTraversalMode();
385 } else if (strcmp(ShenandoahGCMode, "normal") == 0) {
386 _gc_mode = new ShenandoahNormalMode();
387 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
388 _gc_mode = new ShenandoahPassiveMode();
389 } else {
390 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
391 }
392 } else {
393 ShouldNotReachHere();
394 }
395 _gc_mode->initialize_flags();
396 _heuristics = _gc_mode->initialize_heuristics();
397
398 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
399 vm_exit_during_initialization(
400 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
401 _heuristics->name()));
402 }
403 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
404 vm_exit_during_initialization(
405 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
406 _heuristics->name()));
407 }
408 log_info(gc, init)("Shenandoah heuristics: %s",
409 _heuristics->name());
410 }
411
412 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
413 SharedHeap(policy),
414 _shenandoah_policy(policy),
415 _heap_region_special(false),
416 _regions(NULL),
417 _free_set(NULL),
418 _collection_set(NULL),
419 _traversal_gc(NULL),
420 _update_refs_iterator(this),
421 _bytes_allocated_since_gc_start(0),
422 _max_workers((uint)MAX2(ConcGCThreads, ParallelGCThreads)),
423 _ref_processor(NULL),
424 _marking_context(NULL),
425 _bitmap_size(0),
426 _bitmap_regions_per_slice(0),
427 _bitmap_bytes_per_slice(0),
428 _bitmap_region_special(false),
429 _aux_bitmap_region_special(false),
430 _liveness_cache(NULL),
431 _aux_bit_map(),
432 _verifier(NULL),
433 _pacer(NULL),
434 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
435 _phase_timings(NULL),
436 _alloc_tracker(NULL)
437 {
438 log_info(gc, init)("GC threads: " UINTX_FORMAT " parallel, " UINTX_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
439 log_info(gc, init)("Reference processing: %s", ParallelRefProcEnabled ? "parallel" : "serial");
440
441 _scm = new ShenandoahConcurrentMark();
442
443 _full_gc = new ShenandoahMarkCompact();
444 _used = 0;
445
446 _max_workers = MAX2(_max_workers, 1U);
447
448 // SharedHeap did not initialize this for us, and we want our own workgang anyway.
449 assert(SharedHeap::_workers == NULL && _workers == NULL, "Should not be initialized yet");
450 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
451 /* are_GC_task_threads */true,
452 /* are_ConcurrentGC_threads */false);
453 if (_workers == NULL) {
454 vm_exit_during_initialization("Failed necessary allocation.");
455 } else {
456 _workers->initialize_workers();
457 }
458 assert(SharedHeap::_workers == _workers, "Sanity: initialized the correct field");
459 }
460
461 #ifdef _MSC_VER
462 #pragma warning( pop )
463 #endif
464
465 class ShenandoahResetBitmapTask : public AbstractGangTask {
466 private:
467 ShenandoahRegionIterator _regions;
468
469 public:
470 ShenandoahResetBitmapTask() :
471 AbstractGangTask("Parallel Reset Bitmap Task") {}
472
473 void work(uint worker_id) {
474 ShenandoahHeapRegion* region = _regions.next();
475 ShenandoahHeap* heap = ShenandoahHeap::heap();
476 ShenandoahMarkingContext* const ctx = heap->marking_context();
477 while (region != NULL) {
478 if (heap->is_bitmap_slice_committed(region)) {
479 ctx->clear_bitmap(region);
480 }
481 region = _regions.next();
482 }
483 }
484 };
485
486 void ShenandoahHeap::reset_mark_bitmap() {
487 assert_gc_workers(_workers->active_workers());
488 mark_incomplete_marking_context();
489
490 ShenandoahResetBitmapTask task;
491 _workers->run_task(&task);
492 }
493
494 void ShenandoahHeap::print_on(outputStream* st) const {
495 st->print_cr("Shenandoah Heap");
496 st->print_cr(" " SIZE_FORMAT "%s total, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
497 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
498 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
499 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
500 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
501 num_regions(),
502 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
503 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
504
505 st->print("Status: ");
506 if (has_forwarded_objects()) st->print("has forwarded objects, ");
507 if (is_concurrent_mark_in_progress()) st->print("marking, ");
508 if (is_evacuation_in_progress()) st->print("evacuating, ");
509 if (is_update_refs_in_progress()) st->print("updating refs, ");
510 if (is_concurrent_traversal_in_progress()) st->print("traversal, ");
511 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
512 if (is_full_gc_in_progress()) st->print("full gc, ");
513 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
514
515 if (cancelled_gc()) {
516 st->print("cancelled");
517 } else {
518 st->print("not cancelled");
519 }
520 st->cr();
521
522 st->print_cr("Reserved region:");
523 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
524 p2i(reserved_region().start()),
525 p2i(reserved_region().end()));
526
527 ShenandoahCollectionSet* cset = collection_set();
528 st->print_cr("Collection set:");
529 if (cset != NULL) {
530 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
531 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
532 } else {
533 st->print_cr(" (NULL)");
534 }
535
536 st->cr();
537 MetaspaceAux::print_on(st);
538
539 if (Verbose) {
540 print_heap_regions_on(st);
541 }
542 }
543
544 class ShenandoahInitGCLABClosure : public ThreadClosure {
545 public:
546 void do_thread(Thread* thread) {
547 assert(thread == NULL || !thread->is_Java_thread(), "Don't expect JavaThread this early");
548 if (thread != NULL && thread->is_Worker_thread()) {
549 thread->gclab().initialize(true);
550 }
551 }
552 };
553
554 void ShenandoahHeap::post_initialize() {
555 if (UseTLAB) {
556 MutexLocker ml(Threads_lock);
557
558 ShenandoahInitGCLABClosure init_gclabs;
559 Threads::threads_do(&init_gclabs);
560 }
561
562 _scm->initialize(_max_workers);
563 _full_gc->initialize(_gc_timer);
564
565 ref_processing_init();
566
567 _heuristics->initialize();
568 }
569
570 size_t ShenandoahHeap::used() const {
571 OrderAccess::acquire();
572 return (size_t) _used;
573 }
574
575 size_t ShenandoahHeap::committed() const {
576 OrderAccess::acquire();
577 return _committed;
578 }
579
580 void ShenandoahHeap::increase_committed(size_t bytes) {
581 assert_heaplock_or_safepoint();
582 _committed += bytes;
583 }
584
585 void ShenandoahHeap::decrease_committed(size_t bytes) {
586 assert_heaplock_or_safepoint();
587 _committed -= bytes;
588 }
589
590 void ShenandoahHeap::increase_used(size_t bytes) {
591 Atomic::add(bytes, &_used);
592 }
593
594 void ShenandoahHeap::set_used(size_t bytes) {
595 OrderAccess::release_store_fence(&_used, bytes);
596 }
597
598 void ShenandoahHeap::decrease_used(size_t bytes) {
599 assert(used() >= bytes, "never decrease heap size by more than we've left");
600 Atomic::add(-(jlong)bytes, &_used);
601 }
602
603 void ShenandoahHeap::increase_allocated(size_t bytes) {
604 Atomic::add(bytes, &_bytes_allocated_since_gc_start);
605 }
606
607 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
608 size_t bytes = words * HeapWordSize;
609 if (!waste) {
610 increase_used(bytes);
611 }
612 increase_allocated(bytes);
613 if (ShenandoahPacing) {
614 control_thread()->pacing_notify_alloc(words);
615 if (waste) {
616 pacer()->claim_for_alloc(words, true);
617 }
618 }
619 }
620
621 size_t ShenandoahHeap::capacity() const {
622 return committed();
623 }
624
625 size_t ShenandoahHeap::max_capacity() const {
626 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
627 }
628
629 size_t ShenandoahHeap::min_capacity() const {
630 return _minimum_size;
631 }
632
633 size_t ShenandoahHeap::initial_capacity() const {
634 return _initial_size;
635 }
636
637 bool ShenandoahHeap::is_in(const void* p) const {
638 HeapWord* heap_base = (HeapWord*) base();
639 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
640 return p >= heap_base && p < last_region_end;
641 }
642
643 void ShenandoahHeap::op_uncommit(double shrink_before) {
644 assert (ShenandoahUncommit, "should be enabled");
645
646 // Application allocates from the beginning of the heap, and GC allocates at
647 // the end of it. It is more efficient to uncommit from the end, so that applications
648 // could enjoy the near committed regions. GC allocations are much less frequent,
649 // and therefore can accept the committing costs.
650
651 size_t count = 0;
652 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
653 ShenandoahHeapRegion* r = get_region(i - 1);
654 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
655 ShenandoahHeapLocker locker(lock());
656 if (r->is_empty_committed()) {
657 // Do not uncommit below minimal capacity
658 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
659 break;
660 }
661
662 r->make_uncommitted();
663 count++;
664 }
665 }
666 SpinPause(); // allow allocators to take the lock
667 }
668
669 if (count > 0) {
670 _control_thread->notify_heap_changed();
671 }
672 }
673
674 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
675 // Retain tlab and allocate object in shared space if
676 // the amount free in the tlab is too large to discard.
677 if (thread->gclab().free() > thread->gclab().refill_waste_limit()) {
678 thread->gclab().record_slow_allocation(size);
679 return NULL;
680 }
681
682 // Discard gclab and allocate a new one.
683 // To minimize fragmentation, the last GCLAB may be smaller than the rest.
684 size_t new_gclab_size = thread->gclab().compute_size(size);
685
686 thread->gclab().clear_before_allocation();
687
688 if (new_gclab_size == 0) {
689 return NULL;
690 }
691
692 // Allocated object should fit in new GCLAB, and new_gclab_size should be larger than min
693 size_t min_size = MAX2(size + ThreadLocalAllocBuffer::alignment_reserve(), ThreadLocalAllocBuffer::min_size());
694 new_gclab_size = MAX2(new_gclab_size, min_size);
695
696 // Allocate a new GCLAB...
697 size_t actual_size = 0;
698 HeapWord* obj = allocate_new_gclab(min_size, new_gclab_size, &actual_size);
699
700 if (obj == NULL) {
701 return NULL;
702 }
703
704 assert (size <= actual_size, "allocation should fit");
705
706 if (ZeroTLAB) {
707 // ..and clear it.
708 Copy::zero_to_words(obj, actual_size);
709 } else {
710 // ...and zap just allocated object.
711 #ifdef ASSERT
712 // Skip mangling the space corresponding to the object header to
713 // ensure that the returned space is not considered parsable by
714 // any concurrent GC thread.
715 size_t hdr_size = oopDesc::header_size();
716 Copy::fill_to_words(obj + hdr_size, actual_size - hdr_size, badHeapWordVal);
717 #endif // ASSERT
718 }
719 thread->gclab().fill(obj, obj + size, actual_size);
720 return obj;
721 }
722
723 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t word_size) {
724 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(word_size);
725 return allocate_memory(req);
726 }
727
728 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
729 size_t word_size,
730 size_t* actual_size) {
731 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
732 HeapWord* res = allocate_memory(req);
733 if (res != NULL) {
734 *actual_size = req.actual_size();
735 } else {
736 *actual_size = 0;
737 }
738 return res;
739 }
740
741 ShenandoahHeap* ShenandoahHeap::heap() {
742 CollectedHeap* heap = Universe::heap();
743 assert(heap != NULL, "Unitialized access to ShenandoahHeap::heap()");
744 assert(heap->kind() == CollectedHeap::ShenandoahHeap, "not a shenandoah heap");
745 return (ShenandoahHeap*) heap;
746 }
747
748 ShenandoahHeap* ShenandoahHeap::heap_no_check() {
749 CollectedHeap* heap = Universe::heap();
750 return (ShenandoahHeap*) heap;
751 }
752
753 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
754 ShenandoahAllocTrace trace_alloc(req.size(), req.type());
755
756 intptr_t pacer_epoch = 0;
757 bool in_new_region = false;
758 HeapWord* result = NULL;
759
760 if (req.is_mutator_alloc()) {
761 if (ShenandoahPacing) {
762 pacer()->pace_for_alloc(req.size());
763 pacer_epoch = pacer()->epoch();
764 }
765
766 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
767 result = allocate_memory_under_lock(req, in_new_region);
768 }
769
770 // Allocation failed, block until control thread reacted, then retry allocation.
771 //
772 // It might happen that one of the threads requesting allocation would unblock
773 // way later after GC happened, only to fail the second allocation, because
774 // other threads have already depleted the free storage. In this case, a better
775 // strategy is to try again, as long as GC makes progress.
776 //
777 // Then, we need to make sure the allocation was retried after at least one
778 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
779
780 size_t tries = 0;
781
782 while (result == NULL && _progress_last_gc.is_set()) {
783 tries++;
784 control_thread()->handle_alloc_failure(req.size());
785 result = allocate_memory_under_lock(req, in_new_region);
786 }
787
788 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
789 tries++;
790 control_thread()->handle_alloc_failure(req.size());
791 result = allocate_memory_under_lock(req, in_new_region);
792 }
793
794 } else {
795 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
796 result = allocate_memory_under_lock(req, in_new_region);
797 // Do not call handle_alloc_failure() here, because we cannot block.
798 // The allocation failure would be handled by the WB slowpath with handle_alloc_failure_evac().
799 }
800
801 if (in_new_region) {
802 control_thread()->notify_heap_changed();
803 }
804
805 if (result != NULL) {
806 size_t requested = req.size();
807 size_t actual = req.actual_size();
808
809 assert (req.is_lab_alloc() || (requested == actual),
810 err_msg("Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
811 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual));
812
813 if (req.is_mutator_alloc()) {
814 notify_mutator_alloc_words(actual, false);
815
816 // If we requested more than we were granted, give the rest back to pacer.
817 // This only matters if we are in the same pacing epoch: do not try to unpace
818 // over the budget for the other phase.
819 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
820 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
821 }
822 } else {
823 increase_used(actual*HeapWordSize);
824 }
825 }
826
827 return result;
828 }
829
830 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
831 ShenandoahHeapLocker locker(lock());
832 return _free_set->allocate(req, in_new_region);
833 }
834
835 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
836 bool* gc_overhead_limit_was_exceeded) {
837 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
838 HeapWord* result = allocate_memory(req);
839 if (result != NULL) {
840 assert(! in_collection_set(result), "never allocate in targetted region");
841 return result;
842 } else {
843 return NULL;
844 }
845 }
846
847 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
848 private:
849 ShenandoahHeap* const _heap;
850 Thread* const _thread;
851 public:
852 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
853 _heap(heap), _thread(Thread::current()) {}
854
855 void do_object(oop p) {
856 shenandoah_assert_marked(NULL, p);
857 if (!p->is_forwarded()) {
858 _heap->evacuate_object(p, _thread);
859 }
860 }
861 };
862
863 class ShenandoahEvacuationTask : public AbstractGangTask {
864 private:
865 ShenandoahHeap* const _sh;
866 ShenandoahCollectionSet* const _cs;
867 bool _concurrent;
868 public:
869 ShenandoahEvacuationTask(ShenandoahHeap* sh,
870 ShenandoahCollectionSet* cs,
871 bool concurrent) :
872 AbstractGangTask("Parallel Evacuation Task"),
873 _sh(sh),
874 _cs(cs),
875 _concurrent(concurrent)
876 {}
877
878 void work(uint worker_id) {
879 ShenandoahEvacOOMScope oom_evac_scope;
880 if (_concurrent) {
881 ShenandoahConcurrentWorkerSession worker_session(worker_id);
882 do_work();
883 } else {
884 ShenandoahParallelWorkerSession worker_session(worker_id);
885 do_work();
886 }
887 }
888
889 private:
890 void do_work() {
891 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
892 ShenandoahHeapRegion* r;
893 while ((r =_cs->claim_next()) != NULL) {
894 assert(r->has_live(), err_msg("Region " SIZE_FORMAT " should have been reclaimed early", r->region_number()));
895 _sh->marked_object_iterate(r, &cl);
896
897 if (ShenandoahPacing) {
898 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
899 }
900
901 if (_sh->cancelled_gc()) {
902 break;
903 }
904 }
905 }
906 };
907
908 void ShenandoahHeap::trash_cset_regions() {
909 ShenandoahHeapLocker locker(lock());
910
911 ShenandoahCollectionSet* set = collection_set();
912 ShenandoahHeapRegion* r;
913 set->clear_current_index();
914 while ((r = set->next()) != NULL) {
915 r->make_trash();
916 }
917 collection_set()->clear();
918 }
919
920 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
921 st->print_cr("Heap Regions:");
922 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
923 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
924 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start (previous, next)");
925
926 for (size_t i = 0; i < num_regions(); i++) {
927 get_region(i)->print_on(st);
928 }
929 }
930
931 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
932 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
933
934 oop humongous_obj = oop(start->bottom());
935 size_t size = humongous_obj->size();
936 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
937 size_t index = start->region_number() + required_regions - 1;
938
939 assert(!start->has_live(), "liveness must be zero");
940
941 for(size_t i = 0; i < required_regions; i++) {
942 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
943 // as it expects that every region belongs to a humongous region starting with a humongous start region.
944 ShenandoahHeapRegion* region = get_region(index --);
945
946 assert(region->is_humongous(), "expect correct humongous start or continuation");
947 assert(!region->is_cset(), "Humongous region should not be in collection set");
948
949 region->make_trash_immediate();
950 }
951 }
952
953 class ShenandoahRetireGCLABClosure : public ThreadClosure {
954 private:
955 bool _retire;
956 public:
957 ShenandoahRetireGCLABClosure(bool retire) : _retire(retire) {};
958
959 void do_thread(Thread* thread) {
960 assert(thread->gclab().is_initialized(), err_msg("GCLAB should be initialized for %s", thread->name()));
961 thread->gclab().make_parsable(_retire);
962 }
963 };
964
965 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
966 if (UseTLAB) {
967 CollectedHeap::ensure_parsability(retire_tlabs);
968 ShenandoahRetireGCLABClosure cl(retire_tlabs);
969 Threads::java_threads_do(&cl);
970 _workers->threads_do(&cl);
971 }
972 }
973
974 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
975 private:
976 ShenandoahRootEvacuator* _rp;
977
978 public:
979 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
980 AbstractGangTask("Shenandoah evacuate and update roots"),
981 _rp(rp) {}
982
983 void work(uint worker_id) {
984 ShenandoahParallelWorkerSession worker_session(worker_id);
985 ShenandoahEvacOOMScope oom_evac_scope;
986 ShenandoahEvacuateUpdateRootsClosure cl;
987
988 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
989 _rp->process_evacuate_roots(&cl, &blobsCl, worker_id);
990 }
991 };
992
993 void ShenandoahHeap::evacuate_and_update_roots() {
994 COMPILER2_PRESENT(DerivedPointerTable::clear());
995
996 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
997
998 {
999 ShenandoahRootEvacuator rp(this, workers()->active_workers(), ShenandoahPhaseTimings::init_evac);
1000 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1001 workers()->run_task(&roots_task);
1002 }
1003
1004 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1005 }
1006
1007 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1008 // Returns size in bytes
1009 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1010 }
1011
1012 size_t ShenandoahHeap::max_tlab_size() const {
1013 // Returns size in words
1014 return ShenandoahHeapRegion::max_tlab_size_words();
1015 }
1016
1017 class ShenandoahResizeGCLABClosure : public ThreadClosure {
1018 public:
1019 void do_thread(Thread* thread) {
1020 assert(thread->gclab().is_initialized(), err_msg("GCLAB should be initialized for %s", thread->name()));
1021 thread->gclab().resize();
1022 }
1023 };
1024
1025 void ShenandoahHeap::resize_all_tlabs() {
1026 CollectedHeap::resize_all_tlabs();
1027
1028 ShenandoahResizeGCLABClosure cl;
1029 Threads::java_threads_do(&cl);
1030 _workers->threads_do(&cl);
1031 }
1032
1033 class ShenandoahAccumulateStatisticsGCLABClosure : public ThreadClosure {
1034 public:
1035 void do_thread(Thread* thread) {
1036 assert(thread->gclab().is_initialized(), err_msg("GCLAB should be initialized for %s", thread->name()));
1037 thread->gclab().accumulate_statistics();
1038 thread->gclab().initialize_statistics();
1039 }
1040 };
1041
1042 void ShenandoahHeap::accumulate_statistics_all_gclabs() {
1043 ShenandoahAccumulateStatisticsGCLABClosure cl;
1044 Threads::java_threads_do(&cl);
1045 _workers->threads_do(&cl);
1046 }
1047
1048 void ShenandoahHeap::collect(GCCause::Cause cause) {
1049 _control_thread->request_gc(cause);
1050 }
1051
1052 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1053 //assert(false, "Shouldn't need to do full collections");
1054 }
1055
1056 CollectorPolicy* ShenandoahHeap::collector_policy() const {
1057 return _shenandoah_policy;
1058 }
1059
1060 void ShenandoahHeap::resize_tlabs() {
1061 CollectedHeap::resize_all_tlabs();
1062 }
1063
1064 void ShenandoahHeap::accumulate_statistics_tlabs() {
1065 CollectedHeap::accumulate_statistics_all_tlabs();
1066 }
1067
1068 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1069 Space* sp = heap_region_containing(addr);
1070 if (sp != NULL) {
1071 return sp->block_start(addr);
1072 }
1073 return NULL;
1074 }
1075
1076 size_t ShenandoahHeap::block_size(const HeapWord* addr) const {
1077 Space* sp = heap_region_containing(addr);
1078 assert(sp != NULL, "block_size of address outside of heap");
1079 return sp->block_size(addr);
1080 }
1081
1082 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1083 Space* sp = heap_region_containing(addr);
1084 return sp->block_is_obj(addr);
1085 }
1086
1087 jlong ShenandoahHeap::millis_since_last_gc() {
1088 double v = heuristics()->time_since_last_gc() * 1000;
1089 assert(0 <= v && v <= max_jlong, err_msg("value should fit: %f", v));
1090 return (jlong)v;
1091 }
1092
1093 void ShenandoahHeap::prepare_for_verify() {
1094 if (SafepointSynchronize::is_at_safepoint()) {
1095 make_parsable(false);
1096 }
1097 }
1098
1099 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1100 workers()->print_worker_threads_on(st);
1101 if (ShenandoahStringDedup::is_enabled()) {
1102 ShenandoahStringDedup::print_worker_threads_on(st);
1103 }
1104 }
1105
1106 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1107 workers()->threads_do(tcl);
1108 if (ShenandoahStringDedup::is_enabled()) {
1109 ShenandoahStringDedup::threads_do(tcl);
1110 }
1111 }
1112
1113 void ShenandoahHeap::print_tracing_info() const {
1114 if (PrintGC || TraceGen0Time || TraceGen1Time) {
1115 ResourceMark rm;
1116 outputStream* out = gclog_or_tty;
1117 phase_timings()->print_on(out);
1118
1119 out->cr();
1120 out->cr();
1121
1122 shenandoah_policy()->print_gc_stats(out);
1123
1124 out->cr();
1125 out->cr();
1126
1127 if (ShenandoahPacing) {
1128 pacer()->print_on(out);
1129 }
1130
1131 out->cr();
1132 out->cr();
1133
1134 if (ShenandoahAllocationTrace) {
1135 assert(alloc_tracker() != NULL, "Must be");
1136 alloc_tracker()->print_on(out);
1137 } else {
1138 out->print_cr(" Allocation tracing is disabled, use -XX:+ShenandoahAllocationTrace to enable.");
1139 }
1140 }
1141 }
1142
1143 void ShenandoahHeap::verify(bool silent, VerifyOption vo) {
1144 if (ShenandoahSafepoint::is_at_shenandoah_safepoint() || ! UseTLAB) {
1145 if (ShenandoahVerify) {
1146 verifier()->verify_generic(vo);
1147 } else {
1148 // TODO: Consider allocating verification bitmaps on demand,
1149 // and turn this on unconditionally.
1150 }
1151 }
1152 }
1153 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1154 return _free_set->capacity();
1155 }
1156
1157 class ObjectIterateScanRootClosure : public ExtendedOopClosure {
1158 private:
1159 MarkBitMap* _bitmap;
1160 Stack<oop,mtGC>* _oop_stack;
1161
1162 template <class T>
1163 void do_oop_work(T* p) {
1164 T o = oopDesc::load_heap_oop(p);
1165 if (!oopDesc::is_null(o)) {
1166 oop obj = oopDesc::decode_heap_oop_not_null(o);
1167 oop fwd = (oop) ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
1168 if (fwd == NULL) {
1169 // There is an odd interaction with VM_HeapWalkOperation, see jvmtiTagMap.cpp.
1170 //
1171 // That operation walks the reachable objects on its own, storing the marking
1172 // wavefront in the object marks. When it is done, it calls the CollectedHeap
1173 // to iterate over all objects to clean up the mess. When it reaches here,
1174 // the Shenandoah fwdptr resolution code encounters the marked objects with
1175 // NULL forwardee. Trying to act on that would crash the VM. Or fail the
1176 // asserts, should we go for resolve_forwarded_pointer(obj).
1177 //
1178 // Therefore, we have to dodge it by doing the raw access to forwardee, and
1179 // assuming the object had no forwardee, if that thing is NULL.
1180 } else {
1181 obj = fwd;
1182 }
1183 assert(obj->is_oop(), "must be a valid oop");
1184 if (!_bitmap->isMarked((HeapWord*) obj)) {
1185 _bitmap->mark((HeapWord*) obj);
1186 _oop_stack->push(obj);
1187 }
1188 }
1189 }
1190 public:
1191 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1192 _bitmap(bitmap), _oop_stack(oop_stack) {}
1193 void do_oop(oop* p) { do_oop_work(p); }
1194 void do_oop(narrowOop* p) { do_oop_work(p); }
1195 };
1196
1197 /*
1198 * This is public API, used in preparation of object_iterate().
1199 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1200 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1201 * control, we call SH::make_parsable().
1202 */
1203 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1204 // No-op.
1205 }
1206
1207 /*
1208 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1209 *
1210 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1211 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1212 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1213 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1214 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1215 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1216 * wiped the bitmap in preparation for next marking).
1217 *
1218 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1219 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1220 * is allowed to report dead objects, but is not required to do so.
1221 */
1222 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1223 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1224 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1225 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1226 return;
1227 }
1228
1229 // Reset bitmap
1230 _aux_bit_map.clear();
1231
1232 Stack<oop,mtGC> oop_stack;
1233
1234 // First, we process all GC roots. This populates the work stack with initial objects.
1235 ShenandoahRootProcessor rp(this, 1, ShenandoahPhaseTimings::_num_phases);
1236 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1237 CLDToOopClosure clds(&oops, false);
1238 CodeBlobToOopClosure blobs(&oops, false);
1239 rp.process_all_roots(&oops, &clds, &blobs, NULL, 0);
1240
1241 // Work through the oop stack to traverse heap.
1242 while (! oop_stack.is_empty()) {
1243 oop obj = oop_stack.pop();
1244 assert(obj->is_oop(), "must be a valid oop");
1245 cl->do_object(obj);
1246 obj->oop_iterate(&oops);
1247 }
1248
1249 assert(oop_stack.is_empty(), "should be empty");
1250
1251 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1252 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1253 }
1254 }
1255
1256 void ShenandoahHeap::safe_object_iterate(ObjectClosure* cl) {
1257 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1258 object_iterate(cl);
1259 }
1260
1261 void ShenandoahHeap::oop_iterate(ExtendedOopClosure* cl) {
1262 ObjectToOopClosure cl2(cl);
1263 object_iterate(&cl2);
1264 }
1265
1266 class ShenandoahSpaceClosureRegionClosure: public ShenandoahHeapRegionClosure {
1267 SpaceClosure* _cl;
1268 public:
1269 ShenandoahSpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
1270 void heap_region_do(ShenandoahHeapRegion* r) {
1271 _cl->do_space(r);
1272 }
1273 };
1274
1275 void ShenandoahHeap::space_iterate(SpaceClosure* cl) {
1276 ShenandoahSpaceClosureRegionClosure blk(cl);
1277 heap_region_iterate(&blk);
1278 }
1279
1280 Space* ShenandoahHeap::space_containing(const void* oop) const {
1281 Space* res = heap_region_containing(oop);
1282 return res;
1283 }
1284
1285 void ShenandoahHeap::gc_prologue(bool b) {
1286 Unimplemented();
1287 }
1288
1289 void ShenandoahHeap::gc_epilogue(bool b) {
1290 Unimplemented();
1291 }
1292
1293 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1294 for (size_t i = 0; i < num_regions(); i++) {
1295 ShenandoahHeapRegion* current = get_region(i);
1296 blk->heap_region_do(current);
1297 }
1298 }
1299
1300 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1301 private:
1302 ShenandoahHeap* const _heap;
1303 ShenandoahHeapRegionClosure* const _blk;
1304
1305 char _pad0[DEFAULT_CACHE_LINE_SIZE];
1306 volatile jint _index;
1307 char _pad1[DEFAULT_CACHE_LINE_SIZE];
1308
1309 public:
1310 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1311 AbstractGangTask("Parallel Region Task"),
1312 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1313
1314 void work(uint worker_id) {
1315 jint stride = (jint)ShenandoahParallelRegionStride;
1316
1317 jint max = (jint)_heap->num_regions();
1318 while (_index < max) {
1319 jint cur = Atomic::add(stride, &_index) - stride;
1320 jint start = cur;
1321 jint end = MIN2(cur + stride, max);
1322 if (start >= max) break;
1323
1324 for (jint i = cur; i < end; i++) {
1325 ShenandoahHeapRegion* current = _heap->get_region((size_t)i);
1326 _blk->heap_region_do(current);
1327 }
1328 }
1329 }
1330 };
1331
1332 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1333 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1334 if (num_regions() > ShenandoahParallelRegionStride) {
1335 ShenandoahParallelHeapRegionTask task(blk);
1336 workers()->run_task(&task);
1337 } else {
1338 heap_region_iterate(blk);
1339 }
1340 }
1341
1342 class ShenandoahClearLivenessClosure : public ShenandoahHeapRegionClosure {
1343 private:
1344 ShenandoahMarkingContext* const _ctx;
1345 public:
1346 ShenandoahClearLivenessClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1347
1348 void heap_region_do(ShenandoahHeapRegion* r) {
1349 if (r->is_active()) {
1350 r->clear_live_data();
1351 _ctx->capture_top_at_mark_start(r);
1352 } else {
1353 assert(!r->has_live(),
1354 err_msg("Region " SIZE_FORMAT " should have no live data", r->region_number()));
1355 assert(_ctx->top_at_mark_start(r) == r->top(),
1356 err_msg("Region " SIZE_FORMAT " should already have correct TAMS", r->region_number()));
1357 }
1358 }
1359
1360 bool is_thread_safe() { return true; }
1361 };
1362
1363 void ShenandoahHeap::op_init_mark() {
1364 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1365 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1366
1367 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1368 assert(!marking_context()->is_complete(), "should not be complete");
1369
1370 if (ShenandoahVerify) {
1371 verifier()->verify_before_concmark();
1372 }
1373
1374 {
1375 ShenandoahGCPhase phase(ShenandoahPhaseTimings::accumulate_stats);
1376 accumulate_statistics_tlabs();
1377 }
1378
1379 if (VerifyBeforeGC) {
1380 Universe::verify();
1381 }
1382
1383 set_concurrent_mark_in_progress(true);
1384 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1385 if (UseTLAB) {
1386 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1387 make_parsable(true);
1388 }
1389
1390 {
1391 ShenandoahGCPhase phase(ShenandoahPhaseTimings::clear_liveness);
1392 ShenandoahClearLivenessClosure clc;
1393 parallel_heap_region_iterate(&clc);
1394 }
1395
1396 // Make above changes visible to worker threads
1397 OrderAccess::fence();
1398
1399 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1400
1401 if (UseTLAB) {
1402 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1403 resize_tlabs();
1404 }
1405
1406 if (ShenandoahPacing) {
1407 pacer()->setup_for_mark();
1408 }
1409 }
1410
1411 void ShenandoahHeap::op_mark() {
1412 concurrent_mark()->mark_from_roots();
1413 }
1414
1415 class ShenandoahCompleteLivenessClosure : public ShenandoahHeapRegionClosure {
1416 private:
1417 ShenandoahMarkingContext* const _ctx;
1418 public:
1419 ShenandoahCompleteLivenessClosure() : _ctx(ShenandoahHeap::heap()->complete_marking_context()) {}
1420
1421 void heap_region_do(ShenandoahHeapRegion* r) {
1422 if (r->is_active()) {
1423 HeapWord *tams = _ctx->top_at_mark_start(r);
1424 HeapWord *top = r->top();
1425 if (top > tams) {
1426 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1427 }
1428 } else {
1429 assert(!r->has_live(),
1430 err_msg("Region " SIZE_FORMAT " should have no live data", r->region_number()));
1431 assert(_ctx->top_at_mark_start(r) == r->top(),
1432 err_msg("Region " SIZE_FORMAT " should have correct TAMS", r->region_number()));
1433 }
1434 }
1435
1436 bool is_thread_safe() { return true; }
1437 };
1438
1439 void ShenandoahHeap::op_final_mark() {
1440 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1441
1442 // It is critical that we
1443 // evacuate roots right after finishing marking, so that we don't
1444 // get unmarked objects in the roots.
1445
1446 if (!cancelled_gc()) {
1447 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1448
1449 TASKQUEUE_STATS_ONLY(concurrent_mark()->task_queues()->reset_taskqueue_stats());
1450
1451 if (has_forwarded_objects()) {
1452 concurrent_mark()->update_roots(ShenandoahPhaseTimings::update_roots);
1453 }
1454
1455 TASKQUEUE_STATS_ONLY(concurrent_mark()->task_queues()->print_taskqueue_stats());
1456
1457 stop_concurrent_marking();
1458
1459 // All allocations past TAMS are implicitly live, adjust the region data.
1460 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1461 {
1462 ShenandoahGCPhase phase(ShenandoahPhaseTimings::complete_liveness);
1463 ShenandoahCompleteLivenessClosure cl;
1464 parallel_heap_region_iterate(&cl);
1465 }
1466
1467 // Force the threads to reacquire their TLABs outside the collection set.
1468 {
1469 ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs);
1470 make_parsable(true);
1471 }
1472
1473 // We are about to select the collection set, make sure it knows about
1474 // current pinning status. Also, this allows trashing more regions that
1475 // now have their pinning status dropped.
1476 {
1477 ShenandoahGCPhase phase(ShenandoahPhaseTimings::sync_pinned);
1478 sync_pinned_region_status();
1479 }
1480
1481 // Trash the collection set left over from previous cycle, if any.
1482 {
1483 ShenandoahGCPhase phase(ShenandoahPhaseTimings::trash_cset);
1484 trash_cset_regions();
1485 }
1486
1487 {
1488 ShenandoahGCPhase prepare_evac(ShenandoahPhaseTimings::prepare_evac);
1489
1490 ShenandoahHeapLocker locker(lock());
1491 _collection_set->clear();
1492 _free_set->clear();
1493
1494 heuristics()->choose_collection_set(_collection_set);
1495 _free_set->rebuild();
1496 }
1497
1498 // If collection set has candidates, start evacuation.
1499 // Otherwise, bypass the rest of the cycle.
1500 if (!collection_set()->is_empty()) {
1501 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1502
1503 if (ShenandoahVerify) {
1504 verifier()->verify_before_evacuation();
1505 }
1506
1507 set_evacuation_in_progress(true);
1508 // From here on, we need to update references.
1509 set_has_forwarded_objects(true);
1510
1511 evacuate_and_update_roots();
1512
1513 if (ShenandoahPacing) {
1514 pacer()->setup_for_evac();
1515 }
1516
1517 if (ShenandoahVerify) {
1518 verifier()->verify_during_evacuation();
1519 }
1520 } else {
1521 if (ShenandoahVerify) {
1522 verifier()->verify_after_concmark();
1523 }
1524
1525 if (VerifyAfterGC) {
1526 Universe::verify();
1527 }
1528 }
1529
1530 } else {
1531 concurrent_mark()->cancel();
1532 stop_concurrent_marking();
1533
1534 if (process_references()) {
1535 // Abandon reference processing right away: pre-cleaning must have failed.
1536 ReferenceProcessor *rp = ref_processor();
1537 rp->disable_discovery();
1538 rp->abandon_partial_discovery();
1539 rp->verify_no_references_recorded();
1540 }
1541 }
1542 }
1543
1544 void ShenandoahHeap::op_final_evac() {
1545 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1546
1547 set_evacuation_in_progress(false);
1548 if (ShenandoahVerify) {
1549 verifier()->verify_after_evacuation();
1550 }
1551
1552 if (VerifyAfterGC) {
1553 Universe::verify();
1554 }
1555 }
1556
1557 void ShenandoahHeap::op_conc_evac() {
1558 ShenandoahEvacuationTask task(this, _collection_set, true);
1559 workers()->run_task(&task);
1560 }
1561
1562 void ShenandoahHeap::op_stw_evac() {
1563 ShenandoahEvacuationTask task(this, _collection_set, false);
1564 workers()->run_task(&task);
1565 }
1566
1567 void ShenandoahHeap::op_updaterefs() {
1568 update_heap_references(true);
1569 }
1570
1571 void ShenandoahHeap::op_cleanup() {
1572 free_set()->recycle_trash();
1573 }
1574
1575 void ShenandoahHeap::op_reset() {
1576 reset_mark_bitmap();
1577 }
1578
1579 void ShenandoahHeap::op_preclean() {
1580 concurrent_mark()->preclean_weak_refs();
1581 }
1582
1583 void ShenandoahHeap::op_init_traversal() {
1584 traversal_gc()->init_traversal_collection();
1585 }
1586
1587 void ShenandoahHeap::op_traversal() {
1588 traversal_gc()->concurrent_traversal_collection();
1589 }
1590
1591 void ShenandoahHeap::op_final_traversal() {
1592 traversal_gc()->final_traversal_collection();
1593 }
1594
1595 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1596 ShenandoahMetricsSnapshot metrics;
1597 metrics.snap_before();
1598
1599 full_gc()->do_it(cause);
1600
1601 metrics.snap_after();
1602
1603 if (metrics.is_good_progress()) {
1604 _progress_last_gc.set();
1605 } else {
1606 // Nothing to do. Tell the allocation path that we have failed to make
1607 // progress, and it can finally fail.
1608 _progress_last_gc.unset();
1609 }
1610 }
1611
1612 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1613 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1614 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1615 // some phase, we have to upgrade the Degenerate GC to Full GC.
1616
1617 clear_cancelled_gc();
1618
1619 ShenandoahMetricsSnapshot metrics;
1620 metrics.snap_before();
1621
1622 switch (point) {
1623 case _degenerated_traversal:
1624 {
1625 // Drop the collection set. Note: this leaves some already forwarded objects
1626 // behind, which may be problematic, see comments for ShenandoahEvacAssist
1627 // workarounds in ShenandoahTraversalHeuristics.
1628
1629 ShenandoahHeapLocker locker(lock());
1630 collection_set()->clear_current_index();
1631 for (size_t i = 0; i < collection_set()->count(); i++) {
1632 ShenandoahHeapRegion* r = collection_set()->next();
1633 r->make_regular_bypass();
1634 }
1635 collection_set()->clear();
1636 }
1637 op_final_traversal();
1638 op_cleanup();
1639 return;
1640
1641 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1642 // but enters it at different points, depending on which concurrent phase had
1643 // degenerated.
1644
1645 case _degenerated_outside_cycle:
1646 // We have degenerated from outside the cycle, which means something is bad with
1647 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1648 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1649 // we can do the most aggressive degen cycle, which includes processing references and
1650 // class unloading, unless those features are explicitly disabled.
1651 //
1652 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1653 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1654 set_process_references(heuristics()->can_process_references());
1655 set_unload_classes(heuristics()->can_unload_classes());
1656
1657 if (is_traversal_mode()) {
1658 // Not possible to degenerate from here, upgrade to Full GC right away.
1659 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1660 op_degenerated_fail();
1661 return;
1662 }
1663
1664 op_reset();
1665
1666 op_init_mark();
1667 if (cancelled_gc()) {
1668 op_degenerated_fail();
1669 return;
1670 }
1671
1672 case _degenerated_mark:
1673 op_final_mark();
1674 if (cancelled_gc()) {
1675 op_degenerated_fail();
1676 return;
1677 }
1678
1679 op_cleanup();
1680
1681 case _degenerated_evac:
1682 // If heuristics thinks we should do the cycle, this flag would be set,
1683 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
1684 if (is_evacuation_in_progress()) {
1685
1686 // Degeneration under oom-evac protocol might have left some objects in
1687 // collection set un-evacuated. Restart evacuation from the beginning to
1688 // capture all objects. For all the objects that are already evacuated,
1689 // it would be a simple check, which is supposed to be fast. This is also
1690 // safe to do even without degeneration, as CSet iterator is at beginning
1691 // in preparation for evacuation anyway.
1692 //
1693 // Before doing that, we need to make sure we never had any cset-pinned
1694 // regions. This may happen if allocation failure happened when evacuating
1695 // the about-to-be-pinned object, oom-evac protocol left the object in
1696 // the collection set, and then the pin reached the cset region. If we continue
1697 // the cycle here, we would trash the cset and alive objects in it. To avoid
1698 // it, we fail degeneration right away and slide into Full GC to recover.
1699
1700 {
1701 sync_pinned_region_status();
1702 collection_set()->clear_current_index();
1703
1704 ShenandoahHeapRegion* r;
1705 while ((r = collection_set()->next()) != NULL) {
1706 if (r->is_pinned()) {
1707 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1708 op_degenerated_fail();
1709 return;
1710 }
1711 }
1712
1713 collection_set()->clear_current_index();
1714 }
1715
1716 op_stw_evac();
1717 if (cancelled_gc()) {
1718 op_degenerated_fail();
1719 return;
1720 }
1721 }
1722
1723 // If heuristics thinks we should do the cycle, this flag would be set,
1724 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
1725 if (has_forwarded_objects()) {
1726 op_init_updaterefs();
1727 if (cancelled_gc()) {
1728 op_degenerated_fail();
1729 return;
1730 }
1731 }
1732
1733 case _degenerated_updaterefs:
1734 if (has_forwarded_objects()) {
1735 op_final_updaterefs();
1736 if (cancelled_gc()) {
1737 op_degenerated_fail();
1738 return;
1739 }
1740 }
1741
1742 op_cleanup();
1743 break;
1744
1745 default:
1746 ShouldNotReachHere();
1747 }
1748
1749 if (ShenandoahVerify) {
1750 verifier()->verify_after_degenerated();
1751 }
1752
1753 if (VerifyAfterGC) {
1754 Universe::verify();
1755 }
1756
1757 metrics.snap_after();
1758
1759 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
1760 // because that probably means the heap is overloaded and/or fragmented.
1761 if (!metrics.is_good_progress()) {
1762 _progress_last_gc.unset();
1763 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1764 op_degenerated_futile();
1765 } else {
1766 _progress_last_gc.set();
1767 }
1768 }
1769
1770 void ShenandoahHeap::op_degenerated_fail() {
1771 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
1772 shenandoah_policy()->record_degenerated_upgrade_to_full();
1773 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1774 }
1775
1776 void ShenandoahHeap::op_degenerated_futile() {
1777 shenandoah_policy()->record_degenerated_upgrade_to_full();
1778 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1779 }
1780
1781 void ShenandoahHeap::stop_concurrent_marking() {
1782 assert(is_concurrent_mark_in_progress(), "How else could we get here?");
1783 if (!cancelled_gc()) {
1784 // If we needed to update refs, and concurrent marking has been cancelled,
1785 // we need to finish updating references.
1786 set_has_forwarded_objects(false);
1787 mark_complete_marking_context();
1788 }
1789 set_concurrent_mark_in_progress(false);
1790 }
1791
1792 void ShenandoahHeap::force_satb_flush_all_threads() {
1793 if (!is_concurrent_mark_in_progress() && !is_concurrent_traversal_in_progress()) {
1794 // No need to flush SATBs
1795 return;
1796 }
1797
1798 // Do not block if Threads lock is busy. This avoids the potential deadlock
1799 // when this code is called from the periodic task, and something else is
1800 // expecting the periodic task to complete without blocking. On the off-chance
1801 // Threads lock is busy momentarily, try to acquire several times.
1802 for (int t = 0; t < 10; t++) {
1803 if (Threads_lock->try_lock()) {
1804 JavaThread::set_force_satb_flush_all_threads(true);
1805 Threads_lock->unlock();
1806
1807 // The threads are not "acquiring" their thread-local data, but it does not
1808 // hurt to "release" the updates here anyway.
1809 OrderAccess::fence();
1810 break;
1811 }
1812 os::naked_short_sleep(1);
1813 }
1814 }
1815
1816 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1817 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1818 _gc_state.set_cond(mask, value);
1819 JavaThread::set_gc_state_all_threads(_gc_state.raw_value());
1820 }
1821
1822 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1823 set_gc_state_mask(MARKING, in_progress);
1824 JavaThread::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1825 }
1826
1827 void ShenandoahHeap::set_concurrent_traversal_in_progress(bool in_progress) {
1828 set_gc_state_mask(TRAVERSAL | HAS_FORWARDED | UPDATEREFS, in_progress);
1829 JavaThread::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1830 }
1831
1832 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1833 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1834 set_gc_state_mask(EVACUATION, in_progress);
1835 }
1836
1837 void ShenandoahHeap::ref_processing_init() {
1838 MemRegion mr = reserved_region();
1839
1840 assert(_max_workers > 0, "Sanity");
1841
1842 _ref_processor =
1843 new ReferenceProcessor(mr, // span
1844 ParallelRefProcEnabled, // MT processing
1845 _max_workers, // Degree of MT processing
1846 true, // MT discovery
1847 _max_workers, // Degree of MT discovery
1848 false, // Reference discovery is not atomic
1849 NULL); // No closure, should be installed before use
1850
1851 shenandoah_assert_rp_isalive_not_installed();
1852 }
1853
1854 void ShenandoahHeap::acquire_pending_refs_lock() {
1855 _control_thread->slt()->manipulatePLL(SurrogateLockerThread::acquirePLL);
1856 }
1857
1858 void ShenandoahHeap::release_pending_refs_lock() {
1859 _control_thread->slt()->manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL);
1860 }
1861
1862 GCTracer* ShenandoahHeap::tracer() {
1863 return shenandoah_policy()->tracer();
1864 }
1865
1866 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1867 return _free_set->used();
1868 }
1869
1870 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1871 if (try_cancel_gc()) {
1872 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1873 log_info(gc)("%s", msg.buffer());
1874 Events::log(Thread::current(), "%s", msg.buffer());
1875 }
1876 }
1877
1878 uint ShenandoahHeap::max_workers() {
1879 return _max_workers;
1880 }
1881
1882 void ShenandoahHeap::stop() {
1883 // The shutdown sequence should be able to terminate when GC is running.
1884
1885 // Step 0. Notify policy to disable event recording.
1886 _shenandoah_policy->record_shutdown();
1887
1888 // Step 1. Notify control thread that we are in shutdown.
1889 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1890 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1891 _control_thread->prepare_for_graceful_shutdown();
1892
1893 // Step 2. Notify GC workers that we are cancelling GC.
1894 cancel_gc(GCCause::_shenandoah_stop_vm);
1895
1896 // Step 3. Wait until GC worker exits normally.
1897 _control_thread->stop();
1898
1899 // Step 4. Stop String Dedup thread if it is active
1900 if (ShenandoahStringDedup::is_enabled()) {
1901 ShenandoahStringDedup::stop();
1902 }
1903 }
1904
1905 void ShenandoahHeap::unload_classes_and_cleanup_tables(bool full_gc) {
1906 assert(heuristics()->can_unload_classes(), "Class unloading should be enabled");
1907
1908 ShenandoahGCPhase root_phase(full_gc ?
1909 ShenandoahPhaseTimings::full_gc_purge :
1910 ShenandoahPhaseTimings::purge);
1911
1912 ShenandoahIsAliveSelector alive;
1913 BoolObjectClosure* is_alive = alive.is_alive_closure();
1914
1915 bool purged_class;
1916
1917 // Unload classes and purge SystemDictionary.
1918 {
1919 ShenandoahGCPhase phase(full_gc ?
1920 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1921 ShenandoahPhaseTimings::purge_class_unload);
1922 purged_class = SystemDictionary::do_unloading(is_alive,
1923 full_gc /* do_cleaning*/ );
1924 }
1925
1926 {
1927 ShenandoahGCPhase phase(full_gc ?
1928 ShenandoahPhaseTimings::full_gc_purge_par :
1929 ShenandoahPhaseTimings::purge_par);
1930 uint active = _workers->active_workers();
1931 ParallelCleaningTask unlink_task(is_alive, true, true, active, purged_class);
1932 _workers->run_task(&unlink_task);
1933 }
1934
1935 if (ShenandoahStringDedup::is_enabled()) {
1936 ShenandoahGCPhase phase(full_gc ?
1937 ShenandoahPhaseTimings::full_gc_purge_string_dedup :
1938 ShenandoahPhaseTimings::purge_string_dedup);
1939 ShenandoahStringDedup::parallel_cleanup();
1940 }
1941
1942 {
1943 ShenandoahGCPhase phase(full_gc ?
1944 ShenandoahPhaseTimings::full_gc_purge_cldg :
1945 ShenandoahPhaseTimings::purge_cldg);
1946 ClassLoaderDataGraph::purge();
1947 }
1948 }
1949
1950 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
1951 set_gc_state_mask(HAS_FORWARDED, cond);
1952 }
1953
1954 void ShenandoahHeap::set_process_references(bool pr) {
1955 _process_references.set_cond(pr);
1956 }
1957
1958 void ShenandoahHeap::set_unload_classes(bool uc) {
1959 _unload_classes.set_cond(uc);
1960 }
1961
1962 bool ShenandoahHeap::process_references() const {
1963 return _process_references.is_set();
1964 }
1965
1966 bool ShenandoahHeap::unload_classes() const {
1967 return _unload_classes.is_set();
1968 }
1969
1970 address ShenandoahHeap::in_cset_fast_test_addr() {
1971 ShenandoahHeap* heap = ShenandoahHeap::heap();
1972 assert(heap->collection_set() != NULL, "Sanity");
1973 return (address) heap->collection_set()->biased_map_address();
1974 }
1975
1976 address ShenandoahHeap::cancelled_gc_addr() {
1977 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
1978 }
1979
1980 address ShenandoahHeap::gc_state_addr() {
1981 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
1982 }
1983
1984 size_t ShenandoahHeap::conservative_max_heap_alignment() {
1985 size_t align = ShenandoahMaxRegionSize;
1986 if (UseLargePages) {
1987 align = MAX2(align, os::large_page_size());
1988 }
1989 return align;
1990 }
1991
1992 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
1993 return OrderAccess::load_acquire(&_bytes_allocated_since_gc_start);
1994 }
1995
1996 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
1997 OrderAccess::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
1998 }
1999
2000 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2001 _degenerated_gc_in_progress.set_cond(in_progress);
2002 }
2003
2004 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2005 _full_gc_in_progress.set_cond(in_progress);
2006 }
2007
2008 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2009 assert (is_full_gc_in_progress(), "should be");
2010 _full_gc_move_in_progress.set_cond(in_progress);
2011 }
2012
2013 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2014 set_gc_state_mask(UPDATEREFS, in_progress);
2015 }
2016
2017 void ShenandoahHeap::register_nmethod(nmethod* nm) {
2018 ShenandoahCodeRoots::add_nmethod(nm);
2019 }
2020
2021 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
2022 ShenandoahCodeRoots::remove_nmethod(nm);
2023 }
2024
2025 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2026 heap_region_containing(o)->record_pin();
2027 return o;
2028 }
2029
2030 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2031 heap_region_containing(o)->record_unpin();
2032 }
2033
2034 void ShenandoahHeap::sync_pinned_region_status() {
2035 ShenandoahHeapLocker locker(lock());
2036
2037 for (size_t i = 0; i < num_regions(); i++) {
2038 ShenandoahHeapRegion *r = get_region(i);
2039 if (r->is_active()) {
2040 if (r->is_pinned()) {
2041 if (r->pin_count() == 0) {
2042 r->make_unpinned();
2043 }
2044 } else {
2045 if (r->pin_count() > 0) {
2046 r->make_pinned();
2047 }
2048 }
2049 }
2050 }
2051
2052 assert_pinned_region_status();
2053 }
2054
2055 #ifdef ASSERT
2056 void ShenandoahHeap::assert_pinned_region_status() {
2057 for (size_t i = 0; i < num_regions(); i++) {
2058 ShenandoahHeapRegion* r = get_region(i);
2059 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2060 err_msg("Region " SIZE_FORMAT " pinning status is inconsistent", i));
2061 }
2062 }
2063 #endif
2064
2065 GCTimer* ShenandoahHeap::gc_timer() const {
2066 return _gc_timer;
2067 }
2068
2069 #ifdef ASSERT
2070 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2071 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2072
2073 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2074 if (UseDynamicNumberOfGCThreads ||
2075 (FLAG_IS_DEFAULT(ParallelGCThreads) && ForceDynamicNumberOfGCThreads)) {
2076 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2077 } else {
2078 // Use ParallelGCThreads inside safepoints
2079 assert(nworkers == ParallelGCThreads, "Use ParalleGCThreads within safepoints");
2080 }
2081 } else {
2082 if (UseDynamicNumberOfGCThreads ||
2083 (FLAG_IS_DEFAULT(ConcGCThreads) && ForceDynamicNumberOfGCThreads)) {
2084 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2085 } else {
2086 // Use ConcGCThreads outside safepoints
2087 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2088 }
2089 }
2090 }
2091 #endif
2092
2093 ShenandoahVerifier* ShenandoahHeap::verifier() {
2094 guarantee(ShenandoahVerify, "Should be enabled");
2095 assert (_verifier != NULL, "sanity");
2096 return _verifier;
2097 }
2098
2099 ShenandoahUpdateHeapRefsClosure::ShenandoahUpdateHeapRefsClosure() :
2100 _heap(ShenandoahHeap::heap()) {}
2101
2102 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2103 private:
2104 ShenandoahHeap* _heap;
2105 ShenandoahRegionIterator* _regions;
2106 bool _concurrent;
2107
2108 public:
2109 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2110 AbstractGangTask("Concurrent Update References Task"),
2111 _heap(ShenandoahHeap::heap()),
2112 _regions(regions),
2113 _concurrent(concurrent) {
2114 }
2115
2116 void work(uint worker_id) {
2117 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2118 ShenandoahUpdateHeapRefsClosure cl;
2119 ShenandoahHeapRegion* r = _regions->next();
2120 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2121 while (r != NULL) {
2122 HeapWord* top_at_start_ur = r->concurrent_iteration_safe_limit();
2123 assert (top_at_start_ur >= r->bottom(), "sanity");
2124 if (r->is_active() && !r->is_cset()) {
2125 _heap->marked_object_oop_iterate(r, &cl, top_at_start_ur);
2126 }
2127 if (ShenandoahPacing) {
2128 _heap->pacer()->report_updaterefs(pointer_delta(top_at_start_ur, r->bottom()));
2129 }
2130 if (_heap->cancelled_gc()) {
2131 return;
2132 }
2133 r = _regions->next();
2134 }
2135 }
2136 };
2137
2138 void ShenandoahHeap::update_heap_references(bool concurrent) {
2139 ShenandoahUpdateHeapRefsTask task(&_update_refs_iterator, concurrent);
2140 workers()->run_task(&task);
2141 }
2142
2143 void ShenandoahHeap::op_init_updaterefs() {
2144 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2145
2146 set_evacuation_in_progress(false);
2147
2148 if (ShenandoahVerify) {
2149 verifier()->verify_before_updaterefs();
2150 }
2151
2152 set_update_refs_in_progress(true);
2153
2154 {
2155 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_prepare);
2156
2157 make_parsable(true);
2158 for (uint i = 0; i < num_regions(); i++) {
2159 ShenandoahHeapRegion* r = get_region(i);
2160 r->set_concurrent_iteration_safe_limit(r->top());
2161 }
2162
2163 // Reset iterator.
2164 _update_refs_iterator.reset();
2165 }
2166
2167 if (ShenandoahPacing) {
2168 pacer()->setup_for_updaterefs();
2169 }
2170 }
2171
2172 void ShenandoahHeap::op_final_updaterefs() {
2173 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2174
2175 // Check if there is left-over work, and finish it
2176 if (_update_refs_iterator.has_next()) {
2177 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2178
2179 // Finish updating references where we left off.
2180 clear_cancelled_gc();
2181 update_heap_references(false);
2182 }
2183
2184 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2185 // everything. On degenerated paths, cancelled gc would not be set anyway.
2186 if (cancelled_gc()) {
2187 clear_cancelled_gc();
2188 }
2189 assert(!cancelled_gc(), "Should have been done right before");
2190
2191 concurrent_mark()->update_roots(is_degenerated_gc_in_progress() ?
2192 ShenandoahPhaseTimings::degen_gc_update_roots:
2193 ShenandoahPhaseTimings::final_update_refs_roots);
2194
2195 {
2196 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2197 trash_cset_regions();
2198 }
2199
2200 set_has_forwarded_objects(false);
2201 set_update_refs_in_progress(false);
2202
2203 if (ShenandoahVerify) {
2204 verifier()->verify_after_updaterefs();
2205 }
2206
2207 if (VerifyAfterGC) {
2208 Universe::verify();
2209 }
2210
2211 // Drop unnecessary "pinned" state from regions that does not have CP marks
2212 // anymore, as this would allow trashing them below.
2213 {
2214 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_sync_pinned);
2215 sync_pinned_region_status();
2216 }
2217
2218 {
2219 ShenandoahHeapLocker locker(lock());
2220 _free_set->rebuild();
2221 }
2222 }
2223
2224 #ifdef ASSERT
2225 void ShenandoahHeap::assert_heaplock_not_owned_by_current_thread() {
2226 _lock.assert_not_owned_by_current_thread();
2227 }
2228
2229 void ShenandoahHeap::assert_heaplock_owned_by_current_thread() {
2230 _lock.assert_owned_by_current_thread();
2231 }
2232
2233 void ShenandoahHeap::assert_heaplock_or_safepoint() {
2234 _lock.assert_owned_by_current_thread_or_safepoint();
2235 }
2236 #endif
2237
2238 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2239 print_on(st);
2240 print_heap_regions_on(st);
2241 }
2242
2243 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2244 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2245
2246 size_t regions_from = _bitmap_regions_per_slice * slice;
2247 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2248 for (size_t g = regions_from; g < regions_to; g++) {
2249 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2250 if (skip_self && g == r->region_number()) continue;
2251 if (get_region(g)->is_committed()) {
2252 return true;
2253 }
2254 }
2255 return false;
2256 }
2257
2258 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2259 assert_heaplock_owned_by_current_thread();
2260
2261 // Bitmaps in special regions do not need commits
2262 if (_bitmap_region_special) {
2263 return true;
2264 }
2265
2266 if (is_bitmap_slice_committed(r, true)) {
2267 // Some other region from the group is already committed, meaning the bitmap
2268 // slice is already committed, we exit right away.
2269 return true;
2270 }
2271
2272 // Commit the bitmap slice:
2273 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2274 size_t off = _bitmap_bytes_per_slice * slice;
2275 size_t len = _bitmap_bytes_per_slice;
2276 if (!os::commit_memory((char*)_bitmap_region.start() + off, len, false)) {
2277 return false;
2278 }
2279 return true;
2280 }
2281
2282 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2283 assert_heaplock_owned_by_current_thread();
2284
2285 // Bitmaps in special regions do not need uncommits
2286 if (_bitmap_region_special) {
2287 return true;
2288 }
2289
2290 if (is_bitmap_slice_committed(r, true)) {
2291 // Some other region from the group is still committed, meaning the bitmap
2292 // slice is should stay committed, exit right away.
2293 return true;
2294 }
2295
2296 // Uncommit the bitmap slice:
2297 size_t slice = r->region_number() / _bitmap_regions_per_slice;
2298 size_t off = _bitmap_bytes_per_slice * slice;
2299 size_t len = _bitmap_bytes_per_slice;
2300 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2301 return false;
2302 }
2303 return true;
2304 }
2305
2306 void ShenandoahHeap::vmop_entry_init_mark() {
2307 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2308 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2309 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
2310
2311 try_inject_alloc_failure();
2312 VM_ShenandoahInitMark op;
2313 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2314 }
2315
2316 void ShenandoahHeap::vmop_entry_final_mark() {
2317 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2318 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2319 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
2320
2321 try_inject_alloc_failure();
2322 VM_ShenandoahFinalMarkStartEvac op;
2323 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2324 }
2325
2326 void ShenandoahHeap::vmop_entry_final_evac() {
2327 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2328 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2329 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_gross);
2330
2331 VM_ShenandoahFinalEvac op;
2332 VMThread::execute(&op); // jump to entry_final_evac under safepoint
2333 }
2334
2335 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2336 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2337 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2338 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
2339
2340 try_inject_alloc_failure();
2341 VM_ShenandoahInitUpdateRefs op;
2342 VMThread::execute(&op);
2343 }
2344
2345 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2346 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2347 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2348 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
2349
2350 try_inject_alloc_failure();
2351 VM_ShenandoahFinalUpdateRefs op;
2352 VMThread::execute(&op);
2353 }
2354
2355 void ShenandoahHeap::vmop_entry_init_traversal() {
2356 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2357 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2358 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc_gross);
2359
2360 try_inject_alloc_failure();
2361 VM_ShenandoahInitTraversalGC op;
2362 VMThread::execute(&op);
2363 }
2364
2365 void ShenandoahHeap::vmop_entry_final_traversal() {
2366 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2367 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2368 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc_gross);
2369
2370 try_inject_alloc_failure();
2371 VM_ShenandoahFinalTraversalGC op;
2372 VMThread::execute(&op);
2373 }
2374
2375 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2376 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2377 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2378 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
2379
2380 try_inject_alloc_failure();
2381 VM_ShenandoahFullGC op(cause);
2382 VMThread::execute(&op);
2383 }
2384
2385 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2386 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2387 ShenandoahGCPhase total(ShenandoahPhaseTimings::total_pause_gross);
2388 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
2389
2390 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2391 VMThread::execute(°enerated_gc);
2392 }
2393
2394 void ShenandoahHeap::entry_init_mark() {
2395 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2396 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
2397
2398 const char* msg = init_mark_event_message();
2399 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2400 EventMark em("%s", msg);
2401
2402 ShenandoahWorkerScope scope(workers(),
2403 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2404 "init marking");
2405
2406 op_init_mark();
2407 }
2408
2409 void ShenandoahHeap::entry_final_mark() {
2410 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2411 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
2412
2413 const char* msg = final_mark_event_message();
2414 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2415 EventMark em("%s", msg);
2416
2417 ShenandoahWorkerScope scope(workers(),
2418 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2419 "final marking");
2420
2421 op_final_mark();
2422 }
2423
2424 void ShenandoahHeap::entry_final_evac() {
2425 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2426 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac);
2427
2428 const char* msg = "Pause Final Evac";
2429 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2430 EventMark em("%s", msg);
2431
2432 op_final_evac();
2433 }
2434
2435 void ShenandoahHeap::entry_init_updaterefs() {
2436 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2437 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
2438
2439 static const char* msg = "Pause Init Update Refs";
2440 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2441 EventMark em("%s", msg);
2442
2443 // No workers used in this phase, no setup required
2444
2445 op_init_updaterefs();
2446 }
2447
2448 void ShenandoahHeap::entry_final_updaterefs() {
2449 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2450 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
2451
2452 static const char* msg = "Pause Final Update Refs";
2453 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2454 EventMark em("%s", msg);
2455
2456 ShenandoahWorkerScope scope(workers(),
2457 ShenandoahWorkerPolicy::calc_workers_for_final_update_ref(),
2458 "final reference update");
2459
2460 op_final_updaterefs();
2461 }
2462
2463 void ShenandoahHeap::entry_init_traversal() {
2464 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2465 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_traversal_gc);
2466
2467 static const char* msg = "Pause Init Traversal";
2468 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2469 EventMark em("%s", msg);
2470
2471 ShenandoahWorkerScope scope(workers(),
2472 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2473 "init traversal");
2474
2475 op_init_traversal();
2476 }
2477
2478 void ShenandoahHeap::entry_final_traversal() {
2479 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2480 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_traversal_gc);
2481
2482 static const char* msg = "Pause Final Traversal";
2483 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2484 EventMark em("%s", msg);
2485
2486 ShenandoahWorkerScope scope(workers(),
2487 ShenandoahWorkerPolicy::calc_workers_for_stw_traversal(),
2488 "final traversal");
2489
2490 op_final_traversal();
2491 }
2492
2493 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2494 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2495 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
2496
2497 static const char* msg = "Pause Full";
2498 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id(), true);
2499 EventMark em("%s", msg);
2500
2501 ShenandoahWorkerScope scope(workers(),
2502 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2503 "full gc");
2504
2505 op_full(cause);
2506 }
2507
2508 void ShenandoahHeap::entry_degenerated(int point) {
2509 ShenandoahGCPhase total_phase(ShenandoahPhaseTimings::total_pause);
2510 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
2511
2512 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2513 const char* msg = degen_event_message(dpoint);
2514 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id(), true);
2515 EventMark em("%s", msg);
2516
2517 ShenandoahWorkerScope scope(workers(),
2518 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2519 "stw degenerated gc");
2520
2521 set_degenerated_gc_in_progress(true);
2522 op_degenerated(dpoint);
2523 set_degenerated_gc_in_progress(false);
2524 }
2525
2526 void ShenandoahHeap::entry_mark() {
2527 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2528
2529 const char* msg = conc_mark_event_message();
2530 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2531 EventMark em("%s", msg);
2532
2533 ShenandoahWorkerScope scope(workers(),
2534 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2535 "concurrent marking");
2536
2537 try_inject_alloc_failure();
2538 op_mark();
2539 }
2540
2541 void ShenandoahHeap::entry_evac() {
2542 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
2543 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2544
2545 static const char *msg = "Concurrent evacuation";
2546 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2547 EventMark em("%s", msg);
2548
2549 ShenandoahWorkerScope scope(workers(),
2550 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2551 "concurrent evacuation");
2552
2553 try_inject_alloc_failure();
2554 op_conc_evac();
2555 }
2556
2557 void ShenandoahHeap::entry_updaterefs() {
2558 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
2559
2560 static const char* msg = "Concurrent update references";
2561 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2562 EventMark em("%s", msg);
2563
2564 ShenandoahWorkerScope scope(workers(),
2565 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2566 "concurrent reference update");
2567
2568 try_inject_alloc_failure();
2569 op_updaterefs();
2570 }
2571
2572 void ShenandoahHeap::entry_cleanup() {
2573 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup);
2574
2575 static const char* msg = "Concurrent cleanup";
2576 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2577 EventMark em("%s", msg);
2578
2579 // This phase does not use workers, no need for setup
2580
2581 try_inject_alloc_failure();
2582 op_cleanup();
2583 }
2584
2585 void ShenandoahHeap::entry_reset() {
2586 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset);
2587
2588 static const char* msg = "Concurrent reset";
2589 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2590 EventMark em("%s", msg);
2591
2592 ShenandoahWorkerScope scope(workers(),
2593 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2594 "concurrent reset");
2595
2596 try_inject_alloc_failure();
2597 op_reset();
2598 }
2599
2600 void ShenandoahHeap::entry_preclean() {
2601 if (ShenandoahPreclean && process_references()) {
2602 ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
2603
2604 static const char* msg = "Concurrent precleaning";
2605 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2606 EventMark em("%s", msg);
2607
2608 ShenandoahWorkerScope scope(workers(),
2609 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2610 "concurrent preclean",
2611 /* check_workers = */ false);
2612
2613 try_inject_alloc_failure();
2614 op_preclean();
2615 }
2616 }
2617
2618 void ShenandoahHeap::entry_traversal() {
2619 static const char* msg = "Concurrent traversal";
2620 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2621 EventMark em("%s", msg);
2622
2623 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2624
2625 ShenandoahWorkerScope scope(workers(),
2626 ShenandoahWorkerPolicy::calc_workers_for_conc_traversal(),
2627 "concurrent traversal");
2628
2629 try_inject_alloc_failure();
2630 op_traversal();
2631 }
2632
2633 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2634 static const char *msg = "Concurrent uncommit";
2635 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2636 EventMark em("%s", msg);
2637
2638 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit);
2639
2640 op_uncommit(shrink_before);
2641 }
2642
2643 void ShenandoahHeap::try_inject_alloc_failure() {
2644 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2645 _inject_alloc_failure.set();
2646 os::naked_short_sleep(1);
2647 if (cancelled_gc()) {
2648 log_info(gc)("Allocation failure was successfully injected");
2649 }
2650 }
2651 }
2652
2653 bool ShenandoahHeap::should_inject_alloc_failure() {
2654 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2655 }
2656
2657 void ShenandoahHeap::enter_evacuation() {
2658 _oom_evac_handler.enter_evacuation();
2659 }
2660
2661 void ShenandoahHeap::leave_evacuation() {
2662 _oom_evac_handler.leave_evacuation();
2663 }
2664
2665 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2666 _heap(ShenandoahHeap::heap()),
2667 _index(0) {}
2668
2669 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2670 _heap(heap),
2671 _index(0) {}
2672
2673 void ShenandoahRegionIterator::reset() {
2674 _index = 0;
2675 }
2676
2677 bool ShenandoahRegionIterator::has_next() const {
2678 return _index < (jint)_heap->num_regions();
2679 }
2680
2681 char ShenandoahHeap::gc_state() {
2682 return _gc_state.raw_value();
2683 }
2684
2685 const char* ShenandoahHeap::init_mark_event_message() const {
2686 bool update_refs = has_forwarded_objects();
2687 bool proc_refs = process_references();
2688 bool unload_cls = unload_classes();
2689
2690 if (update_refs && proc_refs && unload_cls) {
2691 return "Pause Init Mark (update refs) (process weakrefs) (unload classes)";
2692 } else if (update_refs && proc_refs) {
2693 return "Pause Init Mark (update refs) (process weakrefs)";
2694 } else if (update_refs && unload_cls) {
2695 return "Pause Init Mark (update refs) (unload classes)";
2696 } else if (proc_refs && unload_cls) {
2697 return "Pause Init Mark (process weakrefs) (unload classes)";
2698 } else if (update_refs) {
2699 return "Pause Init Mark (update refs)";
2700 } else if (proc_refs) {
2701 return "Pause Init Mark (process weakrefs)";
2702 } else if (unload_cls) {
2703 return "Pause Init Mark (unload classes)";
2704 } else {
2705 return "Pause Init Mark";
2706 }
2707 }
2708
2709 const char* ShenandoahHeap::final_mark_event_message() const {
2710 bool update_refs = has_forwarded_objects();
2711 bool proc_refs = process_references();
2712 bool unload_cls = unload_classes();
2713
2714 if (update_refs && proc_refs && unload_cls) {
2715 return "Pause Final Mark (update refs) (process weakrefs) (unload classes)";
2716 } else if (update_refs && proc_refs) {
2717 return "Pause Final Mark (update refs) (process weakrefs)";
2718 } else if (update_refs && unload_cls) {
2719 return "Pause Final Mark (update refs) (unload classes)";
2720 } else if (proc_refs && unload_cls) {
2721 return "Pause Final Mark (process weakrefs) (unload classes)";
2722 } else if (update_refs) {
2723 return "Pause Final Mark (update refs)";
2724 } else if (proc_refs) {
2725 return "Pause Final Mark (process weakrefs)";
2726 } else if (unload_cls) {
2727 return "Pause Final Mark (unload classes)";
2728 } else {
2729 return "Pause Final Mark";
2730 }
2731 }
2732
2733 const char* ShenandoahHeap::conc_mark_event_message() const {
2734 bool update_refs = has_forwarded_objects();
2735 bool proc_refs = process_references();
2736 bool unload_cls = unload_classes();
2737
2738 if (update_refs && proc_refs && unload_cls) {
2739 return "Concurrent marking (update refs) (process weakrefs) (unload classes)";
2740 } else if (update_refs && proc_refs) {
2741 return "Concurrent marking (update refs) (process weakrefs)";
2742 } else if (update_refs && unload_cls) {
2743 return "Concurrent marking (update refs) (unload classes)";
2744 } else if (proc_refs && unload_cls) {
2745 return "Concurrent marking (process weakrefs) (unload classes)";
2746 } else if (update_refs) {
2747 return "Concurrent marking (update refs)";
2748 } else if (proc_refs) {
2749 return "Concurrent marking (process weakrefs)";
2750 } else if (unload_cls) {
2751 return "Concurrent marking (unload classes)";
2752 } else {
2753 return "Concurrent marking";
2754 }
2755 }
2756
2757 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
2758 switch (point) {
2759 case _degenerated_unset:
2760 return "Pause Degenerated GC (<UNSET>)";
2761 case _degenerated_traversal:
2762 return "Pause Degenerated GC (Traversal)";
2763 case _degenerated_outside_cycle:
2764 return "Pause Degenerated GC (Outside of Cycle)";
2765 case _degenerated_mark:
2766 return "Pause Degenerated GC (Mark)";
2767 case _degenerated_evac:
2768 return "Pause Degenerated GC (Evacuation)";
2769 case _degenerated_updaterefs:
2770 return "Pause Degenerated GC (Update Refs)";
2771 default:
2772 ShouldNotReachHere();
2773 return "ERROR";
2774 }
2775 }
2776
2777 jushort* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2778 #ifdef ASSERT
2779 assert(_liveness_cache != NULL, "sanity");
2780 assert(worker_id < _max_workers, "sanity");
2781 for (uint i = 0; i < num_regions(); i++) {
2782 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2783 }
2784 #endif
2785 return _liveness_cache[worker_id];
2786 }
2787
2788 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2789 assert(worker_id < _max_workers, "sanity");
2790 assert(_liveness_cache != NULL, "sanity");
2791 jushort* ld = _liveness_cache[worker_id];
2792 for (uint i = 0; i < num_regions(); i++) {
2793 ShenandoahHeapRegion* r = get_region(i);
2794 jushort live = ld[i];
2795 if (live > 0) {
2796 r->increase_live_data_gc_words(live);
2797 ld[i] = 0;
2798 }
2799 }
2800 }