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