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
30 #include "gc_implementation/shenandoah/shenandoahBarrierSet.hpp"
31 #include "gc_implementation/shenandoah/shenandoahClosures.inline.hpp"
32 #include "gc_implementation/shenandoah/shenandoahCollectionSet.hpp"
33 #include "gc_implementation/shenandoah/shenandoahCollectorPolicy.hpp"
34 #include "gc_implementation/shenandoah/shenandoahConcurrentMark.inline.hpp"
35 #include "gc_implementation/shenandoah/shenandoahControlThread.hpp"
36 #include "gc_implementation/shenandoah/shenandoahFreeSet.hpp"
37 #include "gc_implementation/shenandoah/shenandoahPhaseTimings.hpp"
38 #include "gc_implementation/shenandoah/shenandoahHeap.inline.hpp"
39 #include "gc_implementation/shenandoah/shenandoahHeapRegion.inline.hpp"
40 #include "gc_implementation/shenandoah/shenandoahHeapRegionSet.hpp"
41 #include "gc_implementation/shenandoah/shenandoahMarkCompact.hpp"
42 #include "gc_implementation/shenandoah/shenandoahMarkingContext.inline.hpp"
43 #include "gc_implementation/shenandoah/shenandoahMonitoringSupport.hpp"
44 #include "gc_implementation/shenandoah/shenandoahMetrics.hpp"
45 #include "gc_implementation/shenandoah/shenandoahOopClosures.inline.hpp"
46 #include "gc_implementation/shenandoah/shenandoahPacer.inline.hpp"
47 #include "gc_implementation/shenandoah/shenandoahPadding.hpp"
48 #include "gc_implementation/shenandoah/shenandoahParallelCleaning.hpp"
49 #include "gc_implementation/shenandoah/shenandoahRootProcessor.inline.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/shenandoahHeuristics.hpp"
58 #include "gc_implementation/shenandoah/mode/shenandoahIUMode.hpp"
59 #include "gc_implementation/shenandoah/mode/shenandoahPassiveMode.hpp"
60 #include "gc_implementation/shenandoah/mode/shenandoahSATBMode.hpp"
61
62 #include "memory/metaspace.hpp"
63 #include "runtime/vmThread.hpp"
64 #include "services/mallocTracker.hpp"
65
66 ShenandoahHeap* ShenandoahHeap::_heap = NULL;
67
68 class ShenandoahPretouchHeapTask : public AbstractGangTask {
69 private:
70 ShenandoahRegionIterator _regions;
71 const size_t _page_size;
72 public:
73 ShenandoahPretouchHeapTask(size_t page_size) :
74 AbstractGangTask("Shenandoah Pretouch Heap"),
75 _page_size(page_size) {}
76
77 virtual void work(uint worker_id) {
78 ShenandoahHeapRegion* r = _regions.next();
79 while (r != NULL) {
80 if (r->is_committed()) {
81 os::pretouch_memory((char *) r->bottom(), (char *) r->end());
82 }
83 r = _regions.next();
84 }
85 }
86 };
87
88 class ShenandoahPretouchBitmapTask : public AbstractGangTask {
89 private:
90 ShenandoahRegionIterator _regions;
91 char* _bitmap_base;
92 const size_t _bitmap_size;
93 const size_t _page_size;
94 public:
95 ShenandoahPretouchBitmapTask(char* bitmap_base, size_t bitmap_size, size_t page_size) :
96 AbstractGangTask("Shenandoah Pretouch Bitmap"),
97 _bitmap_base(bitmap_base),
98 _bitmap_size(bitmap_size),
99 _page_size(page_size) {}
100
101 virtual void work(uint worker_id) {
102 ShenandoahHeapRegion* r = _regions.next();
103 while (r != NULL) {
104 size_t start = r->index() * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
105 size_t end = (r->index() + 1) * ShenandoahHeapRegion::region_size_bytes() / MarkBitMap::heap_map_factor();
106 assert (end <= _bitmap_size, err_msg("end is sane: " SIZE_FORMAT " < " SIZE_FORMAT, end, _bitmap_size));
107
108 if (r->is_committed()) {
109 os::pretouch_memory(_bitmap_base + start, _bitmap_base + end);
110 }
111
112 r = _regions.next();
113 }
114 }
115 };
116
117 jint ShenandoahHeap::initialize() {
118 CollectedHeap::pre_initialize();
119
120 //
121 // Figure out heap sizing
122 //
123
124 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
125 size_t min_byte_size = collector_policy()->min_heap_byte_size();
126 size_t max_byte_size = collector_policy()->max_heap_byte_size();
127 size_t heap_alignment = collector_policy()->heap_alignment();
128
129 size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
130
131 Universe::check_alignment(max_byte_size, reg_size_bytes, "Shenandoah heap");
132 Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
133
134 _num_regions = ShenandoahHeapRegion::region_count();
135
136 // Now we know the number of regions, initialize the heuristics.
137 initialize_heuristics();
138
139 size_t num_committed_regions = init_byte_size / reg_size_bytes;
140 num_committed_regions = MIN2(num_committed_regions, _num_regions);
141 assert(num_committed_regions <= _num_regions, "sanity");
142 _initial_size = num_committed_regions * reg_size_bytes;
143
144 size_t num_min_regions = min_byte_size / reg_size_bytes;
145 num_min_regions = MIN2(num_min_regions, _num_regions);
146 assert(num_min_regions <= _num_regions, "sanity");
147 _minimum_size = num_min_regions * reg_size_bytes;
148
149 _committed = _initial_size;
150
151 size_t heap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
152 size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
153 size_t region_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
154
155 //
156 // Reserve and commit memory for heap
157 //
158
159 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
160 _reserved.set_word_size(0);
161 _reserved.set_start((HeapWord*)heap_rs.base());
162 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
163 _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
164 _heap_region_special = heap_rs.special();
165
166 assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
167 err_msg("Misaligned heap: " PTR_FORMAT, p2i(base())));
168
169 #if SHENANDOAH_OPTIMIZED_OBJTASK
170 // The optimized ObjArrayChunkedTask takes some bits away from the full object bits.
171 // Fail if we ever attempt to address more than we can.
172 if ((uintptr_t)(heap_rs.base() + heap_rs.size()) >= ObjArrayChunkedTask::max_addressable()) {
173 FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
174 "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
175 "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
176 p2i(heap_rs.base()), p2i(heap_rs.base() + heap_rs.size()), ObjArrayChunkedTask::max_addressable());
177 vm_exit_during_initialization("Fatal Error", buf);
178 }
179 #endif
180
181 ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
182 if (!_heap_region_special) {
183 os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
184 "Cannot commit heap memory");
185 }
186
187 //
188 // Reserve and commit memory for bitmap(s)
189 //
190
191 _bitmap_size = MarkBitMap::compute_size(heap_rs.size());
192 _bitmap_size = align_size_up(_bitmap_size, bitmap_page_size);
193
194 size_t bitmap_bytes_per_region = reg_size_bytes / MarkBitMap::heap_map_factor();
195
196 guarantee(bitmap_bytes_per_region != 0,
197 err_msg("Bitmap bytes per region should not be zero"));
198 guarantee(is_power_of_2(bitmap_bytes_per_region),
199 err_msg("Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region));
200
201 if (bitmap_page_size > bitmap_bytes_per_region) {
202 _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
203 _bitmap_bytes_per_slice = bitmap_page_size;
204 } else {
205 _bitmap_regions_per_slice = 1;
206 _bitmap_bytes_per_slice = bitmap_bytes_per_region;
207 }
208
209 guarantee(_bitmap_regions_per_slice >= 1,
210 err_msg("Should have at least one region per slice: " SIZE_FORMAT,
211 _bitmap_regions_per_slice));
212
213 guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
214 err_msg("Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
215 _bitmap_bytes_per_slice, bitmap_page_size));
216
217 ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
218 MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
219 _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
220 _bitmap_region_special = bitmap.special();
221
222 size_t bitmap_init_commit = _bitmap_bytes_per_slice *
223 align_size_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
224 bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
225 if (!_bitmap_region_special) {
226 os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
227 "Cannot commit bitmap memory");
228 }
229
230 _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
231
232 if (ShenandoahVerify) {
233 ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
234 if (!verify_bitmap.special()) {
235 os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
236 "Cannot commit verification bitmap memory");
237 }
238 MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
239 MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
240 _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
241 _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
242 }
243
244 // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
245 ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
246 MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
247 _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
248 _aux_bitmap_region_special = aux_bitmap.special();
249 _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
250
251 //
252 // Create regions and region sets
253 //
254 size_t region_align = align_size_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
255 size_t region_storage_size = align_size_up(region_align * _num_regions, region_page_size);
256 region_storage_size = align_size_up(region_storage_size, os::vm_allocation_granularity());
257
258 ReservedSpace region_storage(region_storage_size, region_page_size);
259 MemTracker::record_virtual_memory_type(region_storage.base(), mtGC);
260 if (!region_storage.special()) {
261 os::commit_memory_or_exit(region_storage.base(), region_storage_size, region_page_size, false,
262 "Cannot commit region memory");
263 }
264
265 // Try to fit the collection set bitmap at lower addresses. This optimizes code generation for cset checks.
266 // Go up until a sensible limit (subject to encoding constraints) and try to reserve the space there.
267 // If not successful, bite a bullet and allocate at whatever address.
268 {
269 size_t cset_align = MAX2<size_t>(os::vm_page_size(), os::vm_allocation_granularity());
270 size_t cset_size = align_size_up(((size_t) sh_rs.base() + sh_rs.size()) >> ShenandoahHeapRegion::region_size_bytes_shift(), cset_align);
271
272 uintptr_t min = ShenandoahUtils::round_up_power_of_2(cset_align);
273 uintptr_t max = (1u << 30u);
274
275 for (uintptr_t addr = min; addr <= max; addr <<= 1u) {
276 char* req_addr = (char*)addr;
277 assert(is_ptr_aligned(req_addr, cset_align), "Should be aligned");
278 ReservedSpace cset_rs(cset_size, cset_align, false, req_addr);
279 if (cset_rs.is_reserved()) {
280 assert(cset_rs.base() == req_addr, err_msg("Allocated where requested: " PTR_FORMAT ", " PTR_FORMAT, p2i(cset_rs.base()), addr));
281 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
282 break;
283 }
284 }
285
286 if (_collection_set == NULL) {
287 ReservedSpace cset_rs(cset_size, cset_align, false);
288 _collection_set = new ShenandoahCollectionSet(this, cset_rs, sh_rs.base());
289 }
290 }
291
292 _regions = NEW_C_HEAP_ARRAY(ShenandoahHeapRegion*, _num_regions, mtGC);
293 _free_set = new ShenandoahFreeSet(this, _num_regions);
294
295 {
296 ShenandoahHeapLocker locker(lock());
297
298 for (size_t i = 0; i < _num_regions; i++) {
299 HeapWord* start = (HeapWord*)sh_rs.base() + ShenandoahHeapRegion::region_size_words() * i;
300 bool is_committed = i < num_committed_regions;
301 void* loc = region_storage.base() + i * region_align;
302
303 ShenandoahHeapRegion* r = new (loc) ShenandoahHeapRegion(start, i, is_committed);
304 assert(is_ptr_aligned(r, SHENANDOAH_CACHE_LINE_SIZE), "Sanity");
305
306 _marking_context->initialize_top_at_mark_start(r);
307 _regions[i] = r;
308 assert(!collection_set()->is_in(i), "New region should not be in collection set");
309 }
310
311 // Initialize to complete
312 _marking_context->mark_complete();
313
314 _free_set->rebuild();
315 }
316
317 if (AlwaysPreTouch) {
318 // For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
319 // before initialize() below zeroes it with initializing thread. For any given region,
320 // we touch the region and the corresponding bitmaps from the same thread.
321 ShenandoahPushWorkerScope scope(workers(), _max_workers, false);
322
323 _pretouch_heap_page_size = heap_page_size;
324 _pretouch_bitmap_page_size = bitmap_page_size;
325
326 #ifdef LINUX
327 // UseTransparentHugePages would madvise that backing memory can be coalesced into huge
328 // pages. But, the kernel needs to know that every small page is used, in order to coalesce
329 // them into huge one. Therefore, we need to pretouch with smaller pages.
330 if (UseTransparentHugePages) {
331 _pretouch_heap_page_size = (size_t)os::vm_page_size();
332 _pretouch_bitmap_page_size = (size_t)os::vm_page_size();
333 }
334 #endif
335
336 // OS memory managers may want to coalesce back-to-back pages. Make their jobs
337 // simpler by pre-touching continuous spaces (heap and bitmap) separately.
338
339 ShenandoahPretouchBitmapTask bcl(bitmap.base(), _bitmap_size, _pretouch_bitmap_page_size);
340 _workers->run_task(&bcl);
341
342 ShenandoahPretouchHeapTask hcl(_pretouch_heap_page_size);
343 _workers->run_task(&hcl);
344 }
345
346 //
347 // Initialize the rest of GC subsystems
348 //
349
350 set_barrier_set(new ShenandoahBarrierSet(this));
351
352 _liveness_cache = NEW_C_HEAP_ARRAY(ShenandoahLiveData*, _max_workers, mtGC);
353 for (uint worker = 0; worker < _max_workers; worker++) {
354 _liveness_cache[worker] = NEW_C_HEAP_ARRAY(ShenandoahLiveData, _num_regions, mtGC);
355 Copy::fill_to_bytes(_liveness_cache[worker], _num_regions * sizeof(ShenandoahLiveData));
356 }
357
358 // The call below uses stuff (the SATB* things) that are in G1, but probably
359 // belong into a shared location.
360 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
361 SATB_Q_FL_lock,
362 20 /*G1SATBProcessCompletedThreshold */,
363 Shared_SATB_Q_lock);
364
365 _monitoring_support = new ShenandoahMonitoringSupport(this);
366 _phase_timings = new ShenandoahPhaseTimings(max_workers());
367 ShenandoahStringDedup::initialize();
368 ShenandoahCodeRoots::initialize();
369
370 if (ShenandoahPacing) {
371 _pacer = new ShenandoahPacer(this);
372 _pacer->setup_for_idle();
373 } else {
374 _pacer = NULL;
375 }
376
377 _control_thread = new ShenandoahControlThread();
378
379 log_info(gc, init)("Initialize Shenandoah heap: " SIZE_FORMAT "%s initial, " SIZE_FORMAT "%s min, " SIZE_FORMAT "%s max",
380 byte_size_in_proper_unit(_initial_size), proper_unit_for_byte_size(_initial_size),
381 byte_size_in_proper_unit(_minimum_size), proper_unit_for_byte_size(_minimum_size),
382 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity())
383 );
384
385 return JNI_OK;
386 }
387
388 #ifdef _MSC_VER
389 #pragma warning( push )
390 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
391 #endif
392
393 void ShenandoahHeap::initialize_heuristics() {
394 if (ShenandoahGCMode != NULL) {
395 if (strcmp(ShenandoahGCMode, "satb") == 0) {
396 _gc_mode = new ShenandoahSATBMode();
397 } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
398 _gc_mode = new ShenandoahIUMode();
399 } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
400 _gc_mode = new ShenandoahPassiveMode();
401 } else {
402 vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
403 }
404 } else {
405 ShouldNotReachHere();
406 }
407 _gc_mode->initialize_flags();
408 if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
409 vm_exit_during_initialization(
410 err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
411 _gc_mode->name()));
412 }
413 if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
414 vm_exit_during_initialization(
415 err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
416 _gc_mode->name()));
417 }
418 log_info(gc, init)("Shenandoah GC mode: %s",
419 _gc_mode->name());
420
421 _heuristics = _gc_mode->initialize_heuristics();
422
423 if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
424 vm_exit_during_initialization(
425 err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
426 _heuristics->name()));
427 }
428 if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
429 vm_exit_during_initialization(
430 err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
431 _heuristics->name()));
432 }
433 log_info(gc, init)("Shenandoah heuristics: %s",
434 _heuristics->name());
435 }
436
437 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
438 SharedHeap(policy),
439 _shenandoah_policy(policy),
440 _heap_region_special(false),
441 _regions(NULL),
442 _free_set(NULL),
443 _collection_set(NULL),
444 _update_refs_iterator(this),
445 _bytes_allocated_since_gc_start(0),
446 _max_workers((uint)MAX2(ConcGCThreads, ParallelGCThreads)),
447 _ref_processor(NULL),
448 _marking_context(NULL),
449 _bitmap_size(0),
450 _bitmap_regions_per_slice(0),
451 _bitmap_bytes_per_slice(0),
452 _bitmap_region_special(false),
453 _aux_bitmap_region_special(false),
454 _liveness_cache(NULL),
455 _aux_bit_map(),
456 _verifier(NULL),
457 _pacer(NULL),
458 _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
459 _phase_timings(NULL)
460 {
461 _heap = this;
462
463 log_info(gc, init)("GC threads: " UINTX_FORMAT " parallel, " UINTX_FORMAT " concurrent", ParallelGCThreads, ConcGCThreads);
464
465 _scm = new ShenandoahConcurrentMark();
466
467 _full_gc = new ShenandoahMarkCompact();
468 _used = 0;
469
470 _max_workers = MAX2(_max_workers, 1U);
471
472 // SharedHeap did not initialize this for us, and we want our own workgang anyway.
473 assert(SharedHeap::_workers == NULL && _workers == NULL, "Should not be initialized yet");
474 _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
475 /* are_GC_task_threads */true,
476 /* are_ConcurrentGC_threads */false);
477 if (_workers == NULL) {
478 vm_exit_during_initialization("Failed necessary allocation.");
479 } else {
480 _workers->initialize_workers();
481 }
482 assert(SharedHeap::_workers == _workers, "Sanity: initialized the correct field");
483 }
484
485 #ifdef _MSC_VER
486 #pragma warning( pop )
487 #endif
488
489 class ShenandoahResetBitmapTask : public AbstractGangTask {
490 private:
491 ShenandoahRegionIterator _regions;
492
493 public:
494 ShenandoahResetBitmapTask() :
495 AbstractGangTask("Parallel Reset Bitmap Task") {}
496
497 void work(uint worker_id) {
498 ShenandoahHeapRegion* region = _regions.next();
499 ShenandoahHeap* heap = ShenandoahHeap::heap();
500 ShenandoahMarkingContext* const ctx = heap->marking_context();
501 while (region != NULL) {
502 if (heap->is_bitmap_slice_committed(region)) {
503 ctx->clear_bitmap(region);
504 }
505 region = _regions.next();
506 }
507 }
508 };
509
510 void ShenandoahHeap::reset_mark_bitmap() {
511 assert_gc_workers(_workers->active_workers());
512 mark_incomplete_marking_context();
513
514 ShenandoahResetBitmapTask task;
515 _workers->run_task(&task);
516 }
517
518 void ShenandoahHeap::print_on(outputStream* st) const {
519 st->print_cr("Shenandoah Heap");
520 st->print_cr(" " SIZE_FORMAT "%s total, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
521 byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
522 byte_size_in_proper_unit(committed()), proper_unit_for_byte_size(committed()),
523 byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
524 st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
525 num_regions(),
526 byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
527 proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
528
529 st->print("Status: ");
530 if (has_forwarded_objects()) st->print("has forwarded objects, ");
531 if (is_concurrent_mark_in_progress()) st->print("marking, ");
532 if (is_evacuation_in_progress()) st->print("evacuating, ");
533 if (is_update_refs_in_progress()) st->print("updating refs, ");
534 if (is_degenerated_gc_in_progress()) st->print("degenerated gc, ");
535 if (is_full_gc_in_progress()) st->print("full gc, ");
536 if (is_full_gc_move_in_progress()) st->print("full gc move, ");
537
538 if (cancelled_gc()) {
539 st->print("cancelled");
540 } else {
541 st->print("not cancelled");
542 }
543 st->cr();
544
545 st->print_cr("Reserved region:");
546 st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
547 p2i(reserved_region().start()),
548 p2i(reserved_region().end()));
549
550 ShenandoahCollectionSet* cset = collection_set();
551 st->print_cr("Collection set:");
552 if (cset != NULL) {
553 st->print_cr(" - map (vanilla): " PTR_FORMAT, p2i(cset->map_address()));
554 st->print_cr(" - map (biased): " PTR_FORMAT, p2i(cset->biased_map_address()));
555 } else {
556 st->print_cr(" (NULL)");
557 }
558
559 st->cr();
560 MetaspaceAux::print_on(st);
561
562 if (Verbose) {
563 print_heap_regions_on(st);
564 }
565 }
566
567 class ShenandoahInitGCLABClosure : public ThreadClosure {
568 public:
569 void do_thread(Thread* thread) {
570 assert(thread == NULL || !thread->is_Java_thread(), "Don't expect JavaThread this early");
571 if (thread != NULL && thread->is_Worker_thread()) {
572 thread->gclab().initialize(true);
573 }
574 }
575 };
576
577 void ShenandoahHeap::post_initialize() {
578 if (UseTLAB) {
579 MutexLocker ml(Threads_lock);
580
581 ShenandoahInitGCLABClosure init_gclabs;
582 Threads::threads_do(&init_gclabs);
583 }
584
585 _scm->initialize(_max_workers);
586 _full_gc->initialize(_gc_timer);
587
588 ref_processing_init();
589
590 _heuristics->initialize();
591 }
592
593 size_t ShenandoahHeap::used() const {
594 OrderAccess::acquire();
595 return (size_t) _used;
596 }
597
598 size_t ShenandoahHeap::committed() const {
599 OrderAccess::acquire();
600 return _committed;
601 }
602
603 void ShenandoahHeap::increase_committed(size_t bytes) {
604 shenandoah_assert_heaplocked_or_safepoint();
605 _committed += bytes;
606 }
607
608 void ShenandoahHeap::decrease_committed(size_t bytes) {
609 shenandoah_assert_heaplocked_or_safepoint();
610 _committed -= bytes;
611 }
612
613 void ShenandoahHeap::increase_used(size_t bytes) {
614 Atomic::add(bytes, &_used);
615 }
616
617 void ShenandoahHeap::set_used(size_t bytes) {
618 OrderAccess::release_store_fence(&_used, bytes);
619 }
620
621 void ShenandoahHeap::decrease_used(size_t bytes) {
622 assert(used() >= bytes, "never decrease heap size by more than we've left");
623 Atomic::add(-(jlong)bytes, &_used);
624 }
625
626 void ShenandoahHeap::increase_allocated(size_t bytes) {
627 Atomic::add(bytes, &_bytes_allocated_since_gc_start);
628 }
629
630 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
631 size_t bytes = words * HeapWordSize;
632 if (!waste) {
633 increase_used(bytes);
634 }
635 increase_allocated(bytes);
636 if (ShenandoahPacing) {
637 control_thread()->pacing_notify_alloc(words);
638 if (waste) {
639 pacer()->claim_for_alloc(words, true);
640 }
641 }
642 }
643
644 size_t ShenandoahHeap::capacity() const {
645 return committed();
646 }
647
648 size_t ShenandoahHeap::max_capacity() const {
649 return _num_regions * ShenandoahHeapRegion::region_size_bytes();
650 }
651
652 size_t ShenandoahHeap::min_capacity() const {
653 return _minimum_size;
654 }
655
656 size_t ShenandoahHeap::initial_capacity() const {
657 return _initial_size;
658 }
659
660 bool ShenandoahHeap::is_in(const void* p) const {
661 HeapWord* heap_base = (HeapWord*) base();
662 HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
663 return p >= heap_base && p < last_region_end;
664 }
665
666 void ShenandoahHeap::op_uncommit(double shrink_before) {
667 assert (ShenandoahUncommit, "should be enabled");
668
669 // Application allocates from the beginning of the heap, and GC allocates at
670 // the end of it. It is more efficient to uncommit from the end, so that applications
671 // could enjoy the near committed regions. GC allocations are much less frequent,
672 // and therefore can accept the committing costs.
673
674 size_t count = 0;
675 for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
676 ShenandoahHeapRegion* r = get_region(i - 1);
677 if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
678 ShenandoahHeapLocker locker(lock());
679 if (r->is_empty_committed()) {
680 // Do not uncommit below minimal capacity
681 if (committed() < min_capacity() + ShenandoahHeapRegion::region_size_bytes()) {
682 break;
683 }
684
685 r->make_uncommitted();
686 count++;
687 }
688 }
689 SpinPause(); // allow allocators to take the lock
690 }
691
692 if (count > 0) {
693 _control_thread->notify_heap_changed();
694 }
695 }
696
697 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
698 // Retain tlab and allocate object in shared space if
699 // the amount free in the tlab is too large to discard.
700 if (thread->gclab().free() > thread->gclab().refill_waste_limit()) {
701 thread->gclab().record_slow_allocation(size);
702 return NULL;
703 }
704
705 // Discard gclab and allocate a new one.
706 // To minimize fragmentation, the last GCLAB may be smaller than the rest.
707 size_t new_gclab_size = thread->gclab().compute_size(size);
708
709 thread->gclab().clear_before_allocation();
710
711 if (new_gclab_size == 0) {
712 return NULL;
713 }
714
715 // Allocated object should fit in new GCLAB, and new_gclab_size should be larger than min
716 size_t min_size = MAX2(size + ThreadLocalAllocBuffer::alignment_reserve(), ThreadLocalAllocBuffer::min_size());
717 new_gclab_size = MAX2(new_gclab_size, min_size);
718
719 // Allocate a new GCLAB...
720 size_t actual_size = 0;
721 HeapWord* obj = allocate_new_gclab(min_size, new_gclab_size, &actual_size);
722
723 if (obj == NULL) {
724 return NULL;
725 }
726
727 assert (size <= actual_size, "allocation should fit");
728
729 if (ZeroTLAB) {
730 // ..and clear it.
731 Copy::zero_to_words(obj, actual_size);
732 } else {
733 // ...and zap just allocated object.
734 #ifdef ASSERT
735 // Skip mangling the space corresponding to the object header to
736 // ensure that the returned space is not considered parsable by
737 // any concurrent GC thread.
738 size_t hdr_size = oopDesc::header_size();
739 Copy::fill_to_words(obj + hdr_size, actual_size - hdr_size, badHeapWordVal);
740 #endif // ASSERT
741 }
742 thread->gclab().fill(obj, obj + size, actual_size);
743 return obj;
744 }
745
746 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t word_size) {
747 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(word_size);
748 return allocate_memory(req);
749 }
750
751 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
752 size_t word_size,
753 size_t* actual_size) {
754 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
755 HeapWord* res = allocate_memory(req);
756 if (res != NULL) {
757 *actual_size = req.actual_size();
758 } else {
759 *actual_size = 0;
760 }
761 return res;
762 }
763
764 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
765 intptr_t pacer_epoch = 0;
766 bool in_new_region = false;
767 HeapWord* result = NULL;
768
769 if (req.is_mutator_alloc()) {
770 if (ShenandoahPacing) {
771 pacer()->pace_for_alloc(req.size());
772 pacer_epoch = pacer()->epoch();
773 }
774
775 if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
776 result = allocate_memory_under_lock(req, in_new_region);
777 }
778
779 // Allocation failed, block until control thread reacted, then retry allocation.
780 //
781 // It might happen that one of the threads requesting allocation would unblock
782 // way later after GC happened, only to fail the second allocation, because
783 // other threads have already depleted the free storage. In this case, a better
784 // strategy is to try again, as long as GC makes progress.
785 //
786 // Then, we need to make sure the allocation was retried after at least one
787 // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
788
789 size_t tries = 0;
790
791 while (result == NULL && _progress_last_gc.is_set()) {
792 tries++;
793 control_thread()->handle_alloc_failure(req);
794 result = allocate_memory_under_lock(req, in_new_region);
795 }
796
797 while (result == NULL && tries <= ShenandoahFullGCThreshold) {
798 tries++;
799 control_thread()->handle_alloc_failure(req);
800 result = allocate_memory_under_lock(req, in_new_region);
801 }
802
803 } else {
804 assert(req.is_gc_alloc(), "Can only accept GC allocs here");
805 result = allocate_memory_under_lock(req, in_new_region);
806 // Do not call handle_alloc_failure() here, because we cannot block.
807 // The allocation failure would be handled by the WB slowpath with handle_alloc_failure_evac().
808 }
809
810 if (in_new_region) {
811 control_thread()->notify_heap_changed();
812 }
813
814 if (result != NULL) {
815 size_t requested = req.size();
816 size_t actual = req.actual_size();
817
818 assert (req.is_lab_alloc() || (requested == actual),
819 err_msg("Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
820 ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual));
821
822 if (req.is_mutator_alloc()) {
823 notify_mutator_alloc_words(actual, false);
824
825 // If we requested more than we were granted, give the rest back to pacer.
826 // This only matters if we are in the same pacing epoch: do not try to unpace
827 // over the budget for the other phase.
828 if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
829 pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
830 }
831 } else {
832 increase_used(actual*HeapWordSize);
833 }
834 }
835
836 return result;
837 }
838
839 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
840 ShenandoahHeapLocker locker(lock());
841 return _free_set->allocate(req, in_new_region);
842 }
843
844 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
845 bool* gc_overhead_limit_was_exceeded) {
846 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
847 return allocate_memory(req);
848 }
849
850 class ShenandoahConcurrentEvacuateRegionObjectClosure : public ObjectClosure {
851 private:
852 ShenandoahHeap* const _heap;
853 Thread* const _thread;
854 public:
855 ShenandoahConcurrentEvacuateRegionObjectClosure(ShenandoahHeap* heap) :
856 _heap(heap), _thread(Thread::current()) {}
857
858 void do_object(oop p) {
859 shenandoah_assert_marked(NULL, p);
860 if (!p->is_forwarded()) {
861 _heap->evacuate_object(p, _thread);
862 }
863 }
864 };
865
866 class ShenandoahEvacuationTask : public AbstractGangTask {
867 private:
868 ShenandoahHeap* const _sh;
869 ShenandoahCollectionSet* const _cs;
870 bool _concurrent;
871 public:
872 ShenandoahEvacuationTask(ShenandoahHeap* sh,
873 ShenandoahCollectionSet* cs,
874 bool concurrent) :
875 AbstractGangTask("Parallel Evacuation Task"),
876 _sh(sh),
877 _cs(cs),
878 _concurrent(concurrent)
879 {}
880
881 void work(uint worker_id) {
882 ShenandoahEvacOOMScope oom_evac_scope;
883 if (_concurrent) {
884 ShenandoahConcurrentWorkerSession worker_session(worker_id);
885 do_work();
886 } else {
887 ShenandoahParallelWorkerSession worker_session(worker_id);
888 do_work();
889 }
890 }
891
892 private:
893 void do_work() {
894 ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
895 ShenandoahHeapRegion* r;
896 while ((r =_cs->claim_next()) != NULL) {
897 assert(r->has_live(), err_msg("Region " SIZE_FORMAT " should have been reclaimed early", r->index()));
898 _sh->marked_object_iterate(r, &cl);
899
900 if (ShenandoahPacing) {
901 _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
902 }
903
904 if (_sh->cancelled_gc()) {
905 break;
906 }
907 }
908 }
909 };
910
911 void ShenandoahHeap::trash_cset_regions() {
912 ShenandoahHeapLocker locker(lock());
913
914 ShenandoahCollectionSet* set = collection_set();
915 ShenandoahHeapRegion* r;
916 set->clear_current_index();
917 while ((r = set->next()) != NULL) {
918 r->make_trash();
919 }
920 collection_set()->clear();
921 }
922
923 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
924 st->print_cr("Heap Regions:");
925 st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
926 st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
927 st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark");
928 st->print_cr("SN=alloc sequence number");
929
930 for (size_t i = 0; i < num_regions(); i++) {
931 get_region(i)->print_on(st);
932 }
933 }
934
935 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
936 assert(start->is_humongous_start(), "reclaim regions starting with the first one");
937
938 oop humongous_obj = oop(start->bottom());
939 size_t size = humongous_obj->size();
940 size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
941 size_t index = start->index() + required_regions - 1;
942
943 assert(!start->has_live(), "liveness must be zero");
944
945 for(size_t i = 0; i < required_regions; i++) {
946 // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
947 // as it expects that every region belongs to a humongous region starting with a humongous start region.
948 ShenandoahHeapRegion* region = get_region(index --);
949
950 assert(region->is_humongous(), "expect correct humongous start or continuation");
951 assert(!region->is_cset(), "Humongous region should not be in collection set");
952
953 region->make_trash_immediate();
954 }
955 }
956
957 class ShenandoahRetireGCLABClosure : public ThreadClosure {
958 private:
959 bool _retire;
960 public:
961 ShenandoahRetireGCLABClosure(bool retire) : _retire(retire) {};
962
963 void do_thread(Thread* thread) {
964 assert(thread->gclab().is_initialized(), err_msg("GCLAB should be initialized for %s", thread->name()));
965 thread->gclab().make_parsable(_retire);
966 }
967 };
968
969 void ShenandoahHeap::make_parsable(bool retire_tlabs) {
970 if (UseTLAB) {
971 CollectedHeap::ensure_parsability(retire_tlabs);
972 ShenandoahRetireGCLABClosure cl(retire_tlabs);
973 Threads::java_threads_do(&cl);
974 _workers->threads_do(&cl);
975 }
976 }
977
978 class ShenandoahEvacuateUpdateRootsTask : public AbstractGangTask {
979 private:
980 ShenandoahRootEvacuator* _rp;
981
982 public:
983 ShenandoahEvacuateUpdateRootsTask(ShenandoahRootEvacuator* rp) :
984 AbstractGangTask("Shenandoah evacuate and update roots"),
985 _rp(rp) {}
986
987 void work(uint worker_id) {
988 ShenandoahParallelWorkerSession worker_session(worker_id);
989 ShenandoahEvacOOMScope oom_evac_scope;
990 ShenandoahEvacuateUpdateRootsClosure cl;
991
992 MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
993 _rp->roots_do(worker_id, &cl);
994 }
995 };
996
997 void ShenandoahHeap::evacuate_and_update_roots() {
998 COMPILER2_PRESENT(DerivedPointerTable::clear());
999
1000 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only iterate roots while world is stopped");
1001
1002 {
1003 ShenandoahRootEvacuator rp(ShenandoahPhaseTimings::init_evac);
1004 ShenandoahEvacuateUpdateRootsTask roots_task(&rp);
1005 workers()->run_task(&roots_task);
1006 }
1007
1008 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1009 }
1010
1011 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1012 // Returns size in bytes
1013 return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1014 }
1015
1016 size_t ShenandoahHeap::max_tlab_size() const {
1017 // Returns size in words
1018 return ShenandoahHeapRegion::max_tlab_size_words();
1019 }
1020
1021 class ShenandoahResizeGCLABClosure : public ThreadClosure {
1022 public:
1023 void do_thread(Thread* thread) {
1024 assert(thread->gclab().is_initialized(), err_msg("GCLAB should be initialized for %s", thread->name()));
1025 thread->gclab().resize();
1026 }
1027 };
1028
1029 void ShenandoahHeap::resize_all_tlabs() {
1030 CollectedHeap::resize_all_tlabs();
1031
1032 ShenandoahResizeGCLABClosure cl;
1033 Threads::java_threads_do(&cl);
1034 _workers->threads_do(&cl);
1035 }
1036
1037 class ShenandoahAccumulateStatisticsGCLABClosure : public ThreadClosure {
1038 public:
1039 void do_thread(Thread* thread) {
1040 assert(thread->gclab().is_initialized(), err_msg("GCLAB should be initialized for %s", thread->name()));
1041 thread->gclab().accumulate_statistics();
1042 thread->gclab().initialize_statistics();
1043 }
1044 };
1045
1046 void ShenandoahHeap::accumulate_statistics_all_gclabs() {
1047 ShenandoahAccumulateStatisticsGCLABClosure cl;
1048 Threads::java_threads_do(&cl);
1049 _workers->threads_do(&cl);
1050 }
1051
1052 void ShenandoahHeap::collect(GCCause::Cause cause) {
1053 _control_thread->request_gc(cause);
1054 }
1055
1056 void ShenandoahHeap::do_full_collection(bool clear_all_soft_refs) {
1057 //assert(false, "Shouldn't need to do full collections");
1058 }
1059
1060 CollectorPolicy* ShenandoahHeap::collector_policy() const {
1061 return _shenandoah_policy;
1062 }
1063
1064 void ShenandoahHeap::resize_tlabs() {
1065 CollectedHeap::resize_all_tlabs();
1066 }
1067
1068 void ShenandoahHeap::accumulate_statistics_tlabs() {
1069 CollectedHeap::accumulate_statistics_all_tlabs();
1070 }
1071
1072 HeapWord* ShenandoahHeap::block_start(const void* addr) const {
1073 ShenandoahHeapRegion* r = heap_region_containing(addr);
1074 if (r != NULL) {
1075 return r->block_start(addr);
1076 }
1077 return NULL;
1078 }
1079
1080 size_t ShenandoahHeap::block_size(const HeapWord* addr) const {
1081 ShenandoahHeapRegion* r = heap_region_containing(addr);
1082 return r->block_size(addr);
1083 }
1084
1085 bool ShenandoahHeap::block_is_obj(const HeapWord* addr) const {
1086 ShenandoahHeapRegion* r = heap_region_containing(addr);
1087 return r->block_is_obj(addr);
1088 }
1089
1090 jlong ShenandoahHeap::millis_since_last_gc() {
1091 double v = heuristics()->time_since_last_gc() * 1000;
1092 assert(0 <= v && v <= max_jlong, err_msg("value should fit: %f", v));
1093 return (jlong)v;
1094 }
1095
1096 void ShenandoahHeap::prepare_for_verify() {
1097 if (SafepointSynchronize::is_at_safepoint()) {
1098 make_parsable(false);
1099 }
1100 }
1101
1102 void ShenandoahHeap::print_gc_threads_on(outputStream* st) const {
1103 workers()->print_worker_threads_on(st);
1104 if (ShenandoahStringDedup::is_enabled()) {
1105 ShenandoahStringDedup::print_worker_threads_on(st);
1106 }
1107 }
1108
1109 void ShenandoahHeap::gc_threads_do(ThreadClosure* tcl) const {
1110 workers()->threads_do(tcl);
1111 if (ShenandoahStringDedup::is_enabled()) {
1112 ShenandoahStringDedup::threads_do(tcl);
1113 }
1114 }
1115
1116 void ShenandoahHeap::print_tracing_info() const {
1117 if (PrintGC || TraceGen0Time || TraceGen1Time) {
1118 ResourceMark rm;
1119 outputStream* out = gclog_or_tty;
1120 phase_timings()->print_global_on(out);
1121
1122 out->cr();
1123 out->cr();
1124
1125 shenandoah_policy()->print_gc_stats(out);
1126
1127 out->cr();
1128 out->cr();
1129 }
1130 }
1131
1132 void ShenandoahHeap::verify(bool silent, VerifyOption vo) {
1133 if (ShenandoahSafepoint::is_at_shenandoah_safepoint() || ! UseTLAB) {
1134 if (ShenandoahVerify) {
1135 verifier()->verify_generic(vo);
1136 } else {
1137 // TODO: Consider allocating verification bitmaps on demand,
1138 // and turn this on unconditionally.
1139 }
1140 }
1141 }
1142 size_t ShenandoahHeap::tlab_capacity(Thread *thr) const {
1143 return _free_set->capacity();
1144 }
1145
1146 class ObjectIterateScanRootClosure : public ExtendedOopClosure {
1147 private:
1148 MarkBitMap* _bitmap;
1149 Stack<oop,mtGC>* _oop_stack;
1150
1151 template <class T>
1152 void do_oop_work(T* p) {
1153 T o = oopDesc::load_heap_oop(p);
1154 if (!oopDesc::is_null(o)) {
1155 oop obj = oopDesc::decode_heap_oop_not_null(o);
1156 obj = (oop) ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
1157 assert(obj->is_oop(), "must be a valid oop");
1158 if (!_bitmap->isMarked((HeapWord*) obj)) {
1159 _bitmap->mark((HeapWord*) obj);
1160 _oop_stack->push(obj);
1161 }
1162 }
1163 }
1164 public:
1165 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1166 _bitmap(bitmap), _oop_stack(oop_stack) {}
1167 void do_oop(oop* p) { do_oop_work(p); }
1168 void do_oop(narrowOop* p) { do_oop_work(p); }
1169 };
1170
1171 /*
1172 * This is public API, used in preparation of object_iterate().
1173 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1174 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1175 * control, we call SH::make_parsable().
1176 */
1177 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1178 // No-op.
1179 }
1180
1181 /*
1182 * Iterates objects in the heap. This is public API, used for, e.g., heap dumping.
1183 *
1184 * We cannot safely iterate objects by doing a linear scan at random points in time. Linear
1185 * scanning needs to deal with dead objects, which may have dead Klass* pointers (e.g.
1186 * calling oopDesc::size() would crash) or dangling reference fields (crashes) etc. Linear
1187 * scanning therefore depends on having a valid marking bitmap to support it. However, we only
1188 * have a valid marking bitmap after successful marking. In particular, we *don't* have a valid
1189 * marking bitmap during marking, after aborted marking or during/after cleanup (when we just
1190 * wiped the bitmap in preparation for next marking).
1191 *
1192 * For all those reasons, we implement object iteration as a single marking traversal, reporting
1193 * objects as we mark+traverse through the heap, starting from GC roots. JVMTI IterateThroughHeap
1194 * is allowed to report dead objects, but is not required to do so.
1195 */
1196 void ShenandoahHeap::object_iterate(ObjectClosure* cl) {
1197 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1198 if (!_aux_bitmap_region_special && !os::commit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size(), false)) {
1199 log_warning(gc)("Could not commit native memory for auxiliary marking bitmap for heap iteration");
1200 return;
1201 }
1202
1203 // Reset bitmap
1204 _aux_bit_map.clear();
1205
1206 Stack<oop,mtGC> oop_stack;
1207
1208 ObjectIterateScanRootClosure oops(&_aux_bit_map, &oop_stack);
1209
1210 {
1211 // First, we process GC roots according to current GC cycle.
1212 // This populates the work stack with initial objects.
1213 // It is important to relinquish the associated locks before diving
1214 // into heap dumper.
1215 ShenandoahHeapIterationRootScanner rp;
1216 rp.roots_do(&oops);
1217 }
1218
1219 // Work through the oop stack to traverse heap.
1220 while (! oop_stack.is_empty()) {
1221 oop obj = oop_stack.pop();
1222 assert(obj->is_oop(), "must be a valid oop");
1223 cl->do_object(obj);
1224 obj->oop_iterate(&oops);
1225 }
1226
1227 assert(oop_stack.is_empty(), "should be empty");
1228
1229 if (!_aux_bitmap_region_special && !os::uncommit_memory((char*)_aux_bitmap_region.start(), _aux_bitmap_region.byte_size())) {
1230 log_warning(gc)("Could not uncommit native memory for auxiliary marking bitmap for heap iteration");
1231 }
1232 }
1233
1234 void ShenandoahHeap::safe_object_iterate(ObjectClosure* cl) {
1235 assert(SafepointSynchronize::is_at_safepoint(), "safe iteration is only available during safepoints");
1236 object_iterate(cl);
1237 }
1238
1239 void ShenandoahHeap::oop_iterate(ExtendedOopClosure* cl) {
1240 ObjectToOopClosure cl2(cl);
1241 object_iterate(&cl2);
1242 }
1243
1244 void ShenandoahHeap::gc_prologue(bool b) {
1245 Unimplemented();
1246 }
1247
1248 void ShenandoahHeap::gc_epilogue(bool b) {
1249 Unimplemented();
1250 }
1251
1252 void ShenandoahHeap::heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1253 for (size_t i = 0; i < num_regions(); i++) {
1254 ShenandoahHeapRegion* current = get_region(i);
1255 blk->heap_region_do(current);
1256 }
1257 }
1258
1259 class ShenandoahParallelHeapRegionTask : public AbstractGangTask {
1260 private:
1261 ShenandoahHeap* const _heap;
1262 ShenandoahHeapRegionClosure* const _blk;
1263
1264 shenandoah_padding(0);
1265 volatile jint _index;
1266 shenandoah_padding(1);
1267
1268 public:
1269 ShenandoahParallelHeapRegionTask(ShenandoahHeapRegionClosure* blk) :
1270 AbstractGangTask("Parallel Region Task"),
1271 _heap(ShenandoahHeap::heap()), _blk(blk), _index(0) {}
1272
1273 void work(uint worker_id) {
1274 jint stride = (jint)ShenandoahParallelRegionStride;
1275
1276 jint max = (jint)_heap->num_regions();
1277 while (_index < max) {
1278 jint cur = Atomic::add(stride, &_index) - stride;
1279 jint start = cur;
1280 jint end = MIN2(cur + stride, max);
1281 if (start >= max) break;
1282
1283 for (jint i = cur; i < end; i++) {
1284 ShenandoahHeapRegion* current = _heap->get_region((size_t)i);
1285 _blk->heap_region_do(current);
1286 }
1287 }
1288 }
1289 };
1290
1291 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1292 assert(blk->is_thread_safe(), "Only thread-safe closures here");
1293 if (num_regions() > ShenandoahParallelRegionStride) {
1294 ShenandoahParallelHeapRegionTask task(blk);
1295 workers()->run_task(&task);
1296 } else {
1297 heap_region_iterate(blk);
1298 }
1299 }
1300
1301 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1302 private:
1303 ShenandoahMarkingContext* const _ctx;
1304 public:
1305 ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1306
1307 void heap_region_do(ShenandoahHeapRegion* r) {
1308 assert(!r->has_live(),
1309 err_msg("Region " SIZE_FORMAT " should have no live data", r->index()));
1310 if (r->is_active()) {
1311 // Check if region needs updating its TAMS. We have updated it already during concurrent
1312 // reset, so it is very likely we don't need to do another write here.
1313 if (_ctx->top_at_mark_start(r) != r->top()) {
1314 _ctx->capture_top_at_mark_start(r);
1315 }
1316 } else {
1317 assert(_ctx->top_at_mark_start(r) == r->top(),
1318 err_msg("Region " SIZE_FORMAT " should already have correct TAMS", r->index()));
1319 }
1320 }
1321
1322 bool is_thread_safe() { return true; }
1323 };
1324
1325 void ShenandoahHeap::op_init_mark() {
1326 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should be at safepoint");
1327 assert(Thread::current()->is_VM_thread(), "can only do this in VMThread");
1328
1329 assert(marking_context()->is_bitmap_clear(), "need clear marking bitmap");
1330 assert(!marking_context()->is_complete(), "should not be complete");
1331 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1332
1333 if (ShenandoahVerify) {
1334 verifier()->verify_before_concmark();
1335 }
1336
1337 {
1338 ShenandoahGCPhase phase(ShenandoahPhaseTimings::accumulate_stats);
1339 accumulate_statistics_tlabs();
1340 }
1341
1342 if (VerifyBeforeGC) {
1343 Universe::verify();
1344 }
1345
1346 set_concurrent_mark_in_progress(true);
1347 // We need to reset all TLABs because we'd lose marks on all objects allocated in them.
1348 if (UseTLAB) {
1349 ShenandoahGCPhase phase(ShenandoahPhaseTimings::make_parsable);
1350 make_parsable(true);
1351 }
1352
1353 {
1354 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_region_states);
1355 ShenandoahInitMarkUpdateRegionStateClosure cl;
1356 parallel_heap_region_iterate(&cl);
1357 }
1358
1359 // Make above changes visible to worker threads
1360 OrderAccess::fence();
1361
1362 concurrent_mark()->mark_roots(ShenandoahPhaseTimings::scan_roots);
1363
1364 if (UseTLAB) {
1365 ShenandoahGCPhase phase(ShenandoahPhaseTimings::resize_tlabs);
1366 resize_tlabs();
1367 }
1368
1369 if (ShenandoahPacing) {
1370 pacer()->setup_for_mark();
1371 }
1372 }
1373
1374 void ShenandoahHeap::op_mark() {
1375 concurrent_mark()->mark_from_roots();
1376 }
1377
1378 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1379 private:
1380 ShenandoahMarkingContext* const _ctx;
1381 ShenandoahHeapLock* const _lock;
1382
1383 public:
1384 ShenandoahFinalMarkUpdateRegionStateClosure() :
1385 _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1386
1387 void heap_region_do(ShenandoahHeapRegion* r) {
1388 if (r->is_active()) {
1389 // All allocations past TAMS are implicitly live, adjust the region data.
1390 // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1391 HeapWord *tams = _ctx->top_at_mark_start(r);
1392 HeapWord *top = r->top();
1393 if (top > tams) {
1394 r->increase_live_data_alloc_words(pointer_delta(top, tams));
1395 }
1396
1397 // We are about to select the collection set, make sure it knows about
1398 // current pinning status. Also, this allows trashing more regions that
1399 // now have their pinning status dropped.
1400 if (r->is_pinned()) {
1401 if (r->pin_count() == 0) {
1402 ShenandoahHeapLocker locker(_lock);
1403 r->make_unpinned();
1404 }
1405 } else {
1406 if (r->pin_count() > 0) {
1407 ShenandoahHeapLocker locker(_lock);
1408 r->make_pinned();
1409 }
1410 }
1411
1412 // Remember limit for updating refs. It's guaranteed that we get no
1413 // from-space-refs written from here on.
1414 r->set_update_watermark_at_safepoint(r->top());
1415 } else {
1416 assert(!r->has_live(),
1417 err_msg("Region " SIZE_FORMAT " should have no live data", r->index()));
1418 assert(_ctx->top_at_mark_start(r) == r->top(),
1419 err_msg("Region " SIZE_FORMAT " should have correct TAMS", r->index()));
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 assert(!has_forwarded_objects(), "No forwarded objects on this path");
1429
1430 // It is critical that we
1431 // evacuate roots right after finishing marking, so that we don't
1432 // get unmarked objects in the roots.
1433
1434 if (!cancelled_gc()) {
1435 concurrent_mark()->finish_mark_from_roots(/* full_gc = */ false);
1436
1437 TASKQUEUE_STATS_ONLY(concurrent_mark()->task_queues()->reset_taskqueue_stats());
1438
1439 if (ShenandoahVerify) {
1440 verifier()->verify_roots_no_forwarded();
1441 }
1442
1443 TASKQUEUE_STATS_ONLY(concurrent_mark()->task_queues()->print_taskqueue_stats());
1444
1445 stop_concurrent_marking();
1446
1447 {
1448 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_region_states);
1449 ShenandoahFinalMarkUpdateRegionStateClosure cl;
1450 parallel_heap_region_iterate(&cl);
1451
1452 assert_pinned_region_status();
1453 }
1454
1455 // Force the threads to reacquire their TLABs outside the collection set.
1456 {
1457 ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs);
1458 make_parsable(true);
1459 }
1460
1461 {
1462 ShenandoahGCPhase phase(ShenandoahPhaseTimings::choose_cset);
1463 ShenandoahHeapLocker locker(lock());
1464 _collection_set->clear();
1465 heuristics()->choose_collection_set(_collection_set);
1466 }
1467
1468 {
1469 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_rebuild_freeset);
1470 ShenandoahHeapLocker locker(lock());
1471 _free_set->rebuild();
1472 }
1473
1474 // If collection set has candidates, start evacuation.
1475 // Otherwise, bypass the rest of the cycle.
1476 if (!collection_set()->is_empty()) {
1477 ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
1478
1479 if (ShenandoahVerify) {
1480 verifier()->verify_before_evacuation();
1481 }
1482
1483 set_evacuation_in_progress(true);
1484 // From here on, we need to update references.
1485 set_has_forwarded_objects(true);
1486
1487 if (!is_degenerated_gc_in_progress()) {
1488 evacuate_and_update_roots();
1489 }
1490
1491 if (ShenandoahPacing) {
1492 pacer()->setup_for_evac();
1493 }
1494
1495 if (ShenandoahVerify) {
1496 verifier()->verify_roots_no_forwarded();
1497 verifier()->verify_during_evacuation();
1498 }
1499 } else {
1500 if (ShenandoahVerify) {
1501 verifier()->verify_after_concmark();
1502 }
1503
1504 if (VerifyAfterGC) {
1505 Universe::verify();
1506 }
1507 }
1508
1509 } else {
1510 concurrent_mark()->cancel();
1511 stop_concurrent_marking();
1512
1513 if (process_references()) {
1514 // Abandon reference processing right away: pre-cleaning must have failed.
1515 ReferenceProcessor *rp = ref_processor();
1516 rp->disable_discovery();
1517 rp->abandon_partial_discovery();
1518 rp->verify_no_references_recorded();
1519 }
1520 }
1521 }
1522
1523 void ShenandoahHeap::op_conc_evac() {
1524 ShenandoahEvacuationTask task(this, _collection_set, true);
1525 workers()->run_task(&task);
1526 }
1527
1528 void ShenandoahHeap::op_stw_evac() {
1529 ShenandoahEvacuationTask task(this, _collection_set, false);
1530 workers()->run_task(&task);
1531 }
1532
1533 void ShenandoahHeap::op_updaterefs() {
1534 update_heap_references(true);
1535 }
1536
1537 void ShenandoahHeap::op_cleanup_early() {
1538 free_set()->recycle_trash();
1539 }
1540
1541 void ShenandoahHeap::op_cleanup_complete() {
1542 free_set()->recycle_trash();
1543 }
1544
1545 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1546 private:
1547 ShenandoahMarkingContext* const _ctx;
1548 public:
1549 ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1550
1551 void heap_region_do(ShenandoahHeapRegion* r) {
1552 if (r->is_active()) {
1553 // Reset live data and set TAMS optimistically. We would recheck these under the pause
1554 // anyway to capture any updates that happened since now.
1555 r->clear_live_data();
1556 _ctx->capture_top_at_mark_start(r);
1557 }
1558 }
1559
1560 bool is_thread_safe() { return true; }
1561 };
1562
1563 void ShenandoahHeap::op_reset() {
1564 if (ShenandoahPacing) {
1565 pacer()->setup_for_reset();
1566 }
1567 reset_mark_bitmap();
1568
1569 ShenandoahResetUpdateRegionStateClosure cl;
1570 parallel_heap_region_iterate(&cl);
1571 }
1572
1573 void ShenandoahHeap::op_preclean() {
1574 if (ShenandoahPacing) {
1575 pacer()->setup_for_preclean();
1576 }
1577 concurrent_mark()->preclean_weak_refs();
1578 }
1579
1580 void ShenandoahHeap::op_full(GCCause::Cause cause) {
1581 ShenandoahMetricsSnapshot metrics;
1582 metrics.snap_before();
1583
1584 full_gc()->do_it(cause);
1585
1586 metrics.snap_after();
1587
1588 if (metrics.is_good_progress()) {
1589 _progress_last_gc.set();
1590 } else {
1591 // Nothing to do. Tell the allocation path that we have failed to make
1592 // progress, and it can finally fail.
1593 _progress_last_gc.unset();
1594 }
1595 }
1596
1597 void ShenandoahHeap::op_degenerated(ShenandoahDegenPoint point) {
1598 // Degenerated GC is STW, but it can also fail. Current mechanics communicates
1599 // GC failure via cancelled_concgc() flag. So, if we detect the failure after
1600 // some phase, we have to upgrade the Degenerate GC to Full GC.
1601
1602 clear_cancelled_gc();
1603
1604 ShenandoahMetricsSnapshot metrics;
1605 metrics.snap_before();
1606
1607 switch (point) {
1608 // The cases below form the Duff's-like device: it describes the actual GC cycle,
1609 // but enters it at different points, depending on which concurrent phase had
1610 // degenerated.
1611
1612 case _degenerated_outside_cycle:
1613 // We have degenerated from outside the cycle, which means something is bad with
1614 // the heap, most probably heavy humongous fragmentation, or we are very low on free
1615 // space. It makes little sense to wait for Full GC to reclaim as much as it can, when
1616 // we can do the most aggressive degen cycle, which includes processing references and
1617 // class unloading, unless those features are explicitly disabled.
1618 //
1619 // Note that we can only do this for "outside-cycle" degens, otherwise we would risk
1620 // changing the cycle parameters mid-cycle during concurrent -> degenerated handover.
1621 set_process_references(heuristics()->can_process_references());
1622 set_unload_classes(heuristics()->can_unload_classes());
1623
1624 op_reset();
1625
1626 op_init_mark();
1627 if (cancelled_gc()) {
1628 op_degenerated_fail();
1629 return;
1630 }
1631
1632 case _degenerated_mark:
1633 op_final_mark();
1634 if (cancelled_gc()) {
1635 op_degenerated_fail();
1636 return;
1637 }
1638
1639 op_cleanup_early();
1640
1641 case _degenerated_evac:
1642 // If heuristics thinks we should do the cycle, this flag would be set,
1643 // and we can do evacuation. Otherwise, it would be the shortcut cycle.
1644 if (is_evacuation_in_progress()) {
1645
1646 // Degeneration under oom-evac protocol might have left some objects in
1647 // collection set un-evacuated. Restart evacuation from the beginning to
1648 // capture all objects. For all the objects that are already evacuated,
1649 // it would be a simple check, which is supposed to be fast. This is also
1650 // safe to do even without degeneration, as CSet iterator is at beginning
1651 // in preparation for evacuation anyway.
1652 //
1653 // Before doing that, we need to make sure we never had any cset-pinned
1654 // regions. This may happen if allocation failure happened when evacuating
1655 // the about-to-be-pinned object, oom-evac protocol left the object in
1656 // the collection set, and then the pin reached the cset region. If we continue
1657 // the cycle here, we would trash the cset and alive objects in it. To avoid
1658 // it, we fail degeneration right away and slide into Full GC to recover.
1659
1660 {
1661 sync_pinned_region_status();
1662 collection_set()->clear_current_index();
1663
1664 ShenandoahHeapRegion* r;
1665 while ((r = collection_set()->next()) != NULL) {
1666 if (r->is_pinned()) {
1667 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1668 op_degenerated_fail();
1669 return;
1670 }
1671 }
1672
1673 collection_set()->clear_current_index();
1674 }
1675
1676 op_stw_evac();
1677 if (cancelled_gc()) {
1678 op_degenerated_fail();
1679 return;
1680 }
1681 }
1682
1683 // If heuristics thinks we should do the cycle, this flag would be set,
1684 // and we need to do update-refs. Otherwise, it would be the shortcut cycle.
1685 if (has_forwarded_objects()) {
1686 op_init_updaterefs();
1687 if (cancelled_gc()) {
1688 op_degenerated_fail();
1689 return;
1690 }
1691 }
1692
1693 case _degenerated_updaterefs:
1694 if (has_forwarded_objects()) {
1695 op_final_updaterefs();
1696 if (cancelled_gc()) {
1697 op_degenerated_fail();
1698 return;
1699 }
1700 }
1701
1702 op_cleanup_complete();
1703 break;
1704
1705 default:
1706 ShouldNotReachHere();
1707 }
1708
1709 if (ShenandoahVerify) {
1710 verifier()->verify_after_degenerated();
1711 }
1712
1713 if (VerifyAfterGC) {
1714 Universe::verify();
1715 }
1716
1717 metrics.snap_after();
1718
1719 // Check for futility and fail. There is no reason to do several back-to-back Degenerated cycles,
1720 // because that probably means the heap is overloaded and/or fragmented.
1721 if (!metrics.is_good_progress()) {
1722 _progress_last_gc.unset();
1723 cancel_gc(GCCause::_shenandoah_upgrade_to_full_gc);
1724 op_degenerated_futile();
1725 } else {
1726 _progress_last_gc.set();
1727 }
1728 }
1729
1730 void ShenandoahHeap::op_degenerated_fail() {
1731 log_info(gc)("Cannot finish degeneration, upgrading to Full GC");
1732 shenandoah_policy()->record_degenerated_upgrade_to_full();
1733 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1734 }
1735
1736 void ShenandoahHeap::op_degenerated_futile() {
1737 shenandoah_policy()->record_degenerated_upgrade_to_full();
1738 op_full(GCCause::_shenandoah_upgrade_to_full_gc);
1739 }
1740
1741 void ShenandoahHeap::stop_concurrent_marking() {
1742 assert(is_concurrent_mark_in_progress(), "How else could we get here?");
1743 set_concurrent_mark_in_progress(false);
1744 if (!cancelled_gc()) {
1745 // If we needed to update refs, and concurrent marking has been cancelled,
1746 // we need to finish updating references.
1747 set_has_forwarded_objects(false);
1748 mark_complete_marking_context();
1749 }
1750 }
1751
1752 void ShenandoahHeap::force_satb_flush_all_threads() {
1753 if (!is_concurrent_mark_in_progress()) {
1754 // No need to flush SATBs
1755 return;
1756 }
1757
1758 // Do not block if Threads lock is busy. This avoids the potential deadlock
1759 // when this code is called from the periodic task, and something else is
1760 // expecting the periodic task to complete without blocking. On the off-chance
1761 // Threads lock is busy momentarily, try to acquire several times.
1762 for (int t = 0; t < 10; t++) {
1763 if (Threads_lock->try_lock()) {
1764 JavaThread::set_force_satb_flush_all_threads(true);
1765 Threads_lock->unlock();
1766
1767 // The threads are not "acquiring" their thread-local data, but it does not
1768 // hurt to "release" the updates here anyway.
1769 OrderAccess::fence();
1770 break;
1771 }
1772 os::naked_short_sleep(1);
1773 }
1774 }
1775
1776 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1777 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1778 _gc_state.set_cond(mask, value);
1779 JavaThread::set_gc_state_all_threads(_gc_state.raw_value());
1780 }
1781
1782 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1783 if (has_forwarded_objects()) {
1784 set_gc_state_mask(MARKING | UPDATEREFS, in_progress);
1785 } else {
1786 set_gc_state_mask(MARKING, in_progress);
1787 }
1788 JavaThread::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);
1789 }
1790
1791 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1792 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1793 set_gc_state_mask(EVACUATION, in_progress);
1794 }
1795
1796 void ShenandoahHeap::ref_processing_init() {
1797 MemRegion mr = reserved_region();
1798
1799 assert(_max_workers > 0, "Sanity");
1800
1801 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1802 bool mt_discovery = _max_workers > 1;
1803
1804 _ref_processor =
1805 new ReferenceProcessor(mr, // span
1806 mt_processing, // MT processing
1807 _max_workers, // Degree of MT processing
1808 mt_discovery, // MT discovery
1809 _max_workers, // Degree of MT discovery
1810 false, // Reference discovery is not atomic
1811 NULL); // No closure, should be installed before use
1812
1813 log_info(gc, init)("Reference processing: %s discovery, %s processing",
1814 mt_discovery ? "parallel" : "serial",
1815 mt_processing ? "parallel" : "serial");
1816
1817 shenandoah_assert_rp_isalive_not_installed();
1818 }
1819
1820 void ShenandoahHeap::acquire_pending_refs_lock() {
1821 _control_thread->slt()->manipulatePLL(SurrogateLockerThread::acquirePLL);
1822 }
1823
1824 void ShenandoahHeap::release_pending_refs_lock() {
1825 _control_thread->slt()->manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL);
1826 }
1827
1828 GCTracer* ShenandoahHeap::tracer() {
1829 return shenandoah_policy()->tracer();
1830 }
1831
1832 size_t ShenandoahHeap::tlab_used(Thread* thread) const {
1833 return _free_set->used();
1834 }
1835
1836 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1837 if (try_cancel_gc()) {
1838 FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1839 log_info(gc)("%s", msg.buffer());
1840 Events::log(Thread::current(), "%s", msg.buffer());
1841 }
1842 }
1843
1844 uint ShenandoahHeap::max_workers() {
1845 return _max_workers;
1846 }
1847
1848 void ShenandoahHeap::stop() {
1849 // The shutdown sequence should be able to terminate when GC is running.
1850
1851 // Step 0. Notify policy to disable event recording.
1852 _shenandoah_policy->record_shutdown();
1853
1854 // Step 1. Notify control thread that we are in shutdown.
1855 // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1856 // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1857 _control_thread->prepare_for_graceful_shutdown();
1858
1859 // Step 2. Notify GC workers that we are cancelling GC.
1860 cancel_gc(GCCause::_shenandoah_stop_vm);
1861
1862 // Step 3. Wait until GC worker exits normally.
1863 _control_thread->stop();
1864
1865 // Step 4. Stop String Dedup thread if it is active
1866 if (ShenandoahStringDedup::is_enabled()) {
1867 ShenandoahStringDedup::stop();
1868 }
1869 }
1870
1871 void ShenandoahHeap::unload_classes_and_cleanup_tables(bool full_gc) {
1872 assert(heuristics()->can_unload_classes(), "Class unloading should be enabled");
1873
1874 ShenandoahGCPhase root_phase(full_gc ?
1875 ShenandoahPhaseTimings::full_gc_purge :
1876 ShenandoahPhaseTimings::purge);
1877
1878 ShenandoahIsAliveSelector alive;
1879 BoolObjectClosure* is_alive = alive.is_alive_closure();
1880
1881 // Cleaning of klasses depends on correct information from MetadataMarkOnStack. The CodeCache::mark_on_stack
1882 // part is too slow to be done serially, so it is handled during the ShenandoahParallelCleaning phase.
1883 // Defer the cleaning until we have complete on_stack data.
1884 MetadataOnStackMark md_on_stack(false /* Don't visit the code cache at this point */);
1885
1886 bool purged_class;
1887
1888 // Unload classes and purge SystemDictionary.
1889 {
1890 ShenandoahGCPhase phase(full_gc ?
1891 ShenandoahPhaseTimings::full_gc_purge_class_unload :
1892 ShenandoahPhaseTimings::purge_class_unload);
1893 purged_class = SystemDictionary::do_unloading(is_alive,
1894 false /* Defer klass cleaning */);
1895 }
1896 {
1897 ShenandoahGCPhase phase(full_gc ?
1898 ShenandoahPhaseTimings::full_gc_purge_par :
1899 ShenandoahPhaseTimings::purge_par);
1900 uint active = _workers->active_workers();
1901 ShenandoahParallelCleaningTask unlink_task(is_alive, true, true, active, purged_class);
1902 _workers->run_task(&unlink_task);
1903 }
1904
1905 {
1906 ShenandoahGCPhase phase(full_gc ?
1907 ShenandoahPhaseTimings::full_gc_purge_metadata :
1908 ShenandoahPhaseTimings::purge_metadata);
1909 ClassLoaderDataGraph::free_deallocate_lists();
1910 }
1911
1912 if (ShenandoahStringDedup::is_enabled()) {
1913 ShenandoahGCPhase phase(full_gc ?
1914 ShenandoahPhaseTimings::full_gc_purge_string_dedup :
1915 ShenandoahPhaseTimings::purge_string_dedup);
1916 ShenandoahStringDedup::parallel_cleanup();
1917 }
1918
1919 {
1920 ShenandoahGCPhase phase(full_gc ?
1921 ShenandoahPhaseTimings::full_gc_purge_cldg :
1922 ShenandoahPhaseTimings::purge_cldg);
1923 ClassLoaderDataGraph::purge();
1924 }
1925 }
1926
1927 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
1928 set_gc_state_mask(HAS_FORWARDED, cond);
1929 }
1930
1931 void ShenandoahHeap::set_process_references(bool pr) {
1932 _process_references.set_cond(pr);
1933 }
1934
1935 void ShenandoahHeap::set_unload_classes(bool uc) {
1936 _unload_classes.set_cond(uc);
1937 }
1938
1939 bool ShenandoahHeap::process_references() const {
1940 return _process_references.is_set();
1941 }
1942
1943 bool ShenandoahHeap::unload_classes() const {
1944 return _unload_classes.is_set();
1945 }
1946
1947 address ShenandoahHeap::in_cset_fast_test_addr() {
1948 ShenandoahHeap* heap = ShenandoahHeap::heap();
1949 assert(heap->collection_set() != NULL, "Sanity");
1950 return (address) heap->collection_set()->biased_map_address();
1951 }
1952
1953 address ShenandoahHeap::cancelled_gc_addr() {
1954 return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
1955 }
1956
1957 address ShenandoahHeap::gc_state_addr() {
1958 return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
1959 }
1960
1961 size_t ShenandoahHeap::conservative_max_heap_alignment() {
1962 size_t align = ShenandoahMaxRegionSize;
1963 if (UseLargePages) {
1964 align = MAX2(align, os::large_page_size());
1965 }
1966 return align;
1967 }
1968
1969 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
1970 return OrderAccess::load_acquire(&_bytes_allocated_since_gc_start);
1971 }
1972
1973 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
1974 OrderAccess::release_store_fence(&_bytes_allocated_since_gc_start, (size_t)0);
1975 }
1976
1977 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
1978 _degenerated_gc_in_progress.set_cond(in_progress);
1979 }
1980
1981 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
1982 _full_gc_in_progress.set_cond(in_progress);
1983 }
1984
1985 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
1986 assert (is_full_gc_in_progress(), "should be");
1987 _full_gc_move_in_progress.set_cond(in_progress);
1988 }
1989
1990 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
1991 set_gc_state_mask(UPDATEREFS, in_progress);
1992 }
1993
1994 void ShenandoahHeap::register_nmethod(nmethod* nm) {
1995 ShenandoahCodeRoots::add_nmethod(nm);
1996 }
1997
1998 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
1999 ShenandoahCodeRoots::remove_nmethod(nm);
2000 }
2001
2002 oop ShenandoahHeap::pin_object(JavaThread* thr, oop o) {
2003 heap_region_containing(o)->record_pin();
2004 return o;
2005 }
2006
2007 void ShenandoahHeap::unpin_object(JavaThread* thr, oop o) {
2008 heap_region_containing(o)->record_unpin();
2009 }
2010
2011 void ShenandoahHeap::sync_pinned_region_status() {
2012 ShenandoahHeapLocker locker(lock());
2013
2014 for (size_t i = 0; i < num_regions(); i++) {
2015 ShenandoahHeapRegion *r = get_region(i);
2016 if (r->is_active()) {
2017 if (r->is_pinned()) {
2018 if (r->pin_count() == 0) {
2019 r->make_unpinned();
2020 }
2021 } else {
2022 if (r->pin_count() > 0) {
2023 r->make_pinned();
2024 }
2025 }
2026 }
2027 }
2028
2029 assert_pinned_region_status();
2030 }
2031
2032 #ifdef ASSERT
2033 void ShenandoahHeap::assert_pinned_region_status() {
2034 for (size_t i = 0; i < num_regions(); i++) {
2035 ShenandoahHeapRegion* r = get_region(i);
2036 assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2037 err_msg("Region " SIZE_FORMAT " pinning status is inconsistent", i));
2038 }
2039 }
2040 #endif
2041
2042 GCTimer* ShenandoahHeap::gc_timer() const {
2043 return _gc_timer;
2044 }
2045
2046 #ifdef ASSERT
2047 void ShenandoahHeap::assert_gc_workers(uint nworkers) {
2048 assert(nworkers > 0 && nworkers <= max_workers(), "Sanity");
2049
2050 if (ShenandoahSafepoint::is_at_shenandoah_safepoint()) {
2051 if (UseDynamicNumberOfGCThreads ||
2052 (FLAG_IS_DEFAULT(ParallelGCThreads) && ForceDynamicNumberOfGCThreads)) {
2053 assert(nworkers <= ParallelGCThreads, "Cannot use more than it has");
2054 } else {
2055 // Use ParallelGCThreads inside safepoints
2056 assert(nworkers == ParallelGCThreads, "Use ParalleGCThreads within safepoints");
2057 }
2058 } else {
2059 if (UseDynamicNumberOfGCThreads ||
2060 (FLAG_IS_DEFAULT(ConcGCThreads) && ForceDynamicNumberOfGCThreads)) {
2061 assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2062 } else {
2063 // Use ConcGCThreads outside safepoints
2064 assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2065 }
2066 }
2067 }
2068 #endif
2069
2070 ShenandoahVerifier* ShenandoahHeap::verifier() {
2071 guarantee(ShenandoahVerify, "Should be enabled");
2072 assert (_verifier != NULL, "sanity");
2073 return _verifier;
2074 }
2075
2076 ShenandoahUpdateHeapRefsClosure::ShenandoahUpdateHeapRefsClosure() :
2077 _heap(ShenandoahHeap::heap()) {}
2078
2079 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2080 private:
2081 ShenandoahHeap* _heap;
2082 ShenandoahRegionIterator* _regions;
2083 bool _concurrent;
2084
2085 public:
2086 ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool concurrent) :
2087 AbstractGangTask("Concurrent Update References Task"),
2088 _heap(ShenandoahHeap::heap()),
2089 _regions(regions),
2090 _concurrent(concurrent) {
2091 }
2092
2093 void work(uint worker_id) {
2094 ShenandoahConcurrentWorkerSession worker_session(worker_id);
2095 ShenandoahUpdateHeapRefsClosure cl;
2096 ShenandoahHeapRegion* r = _regions->next();
2097 ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();
2098 while (r != NULL) {
2099 HeapWord* update_watermark = r->get_update_watermark();
2100 assert (update_watermark >= r->bottom(), "sanity");
2101 if (r->is_active() && !r->is_cset()) {
2102 _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2103 }
2104 if (ShenandoahPacing) {
2105 _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2106 }
2107 if (_heap->cancelled_gc()) {
2108 return;
2109 }
2110 r = _regions->next();
2111 }
2112 }
2113 };
2114
2115 void ShenandoahHeap::update_heap_references(bool concurrent) {
2116 ShenandoahUpdateHeapRefsTask task(&_update_refs_iterator, concurrent);
2117 workers()->run_task(&task);
2118 }
2119
2120 void ShenandoahHeap::op_init_updaterefs() {
2121 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2122
2123 set_evacuation_in_progress(false);
2124
2125 if (ShenandoahVerify) {
2126 if (!is_degenerated_gc_in_progress()) {
2127 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots);
2128 }
2129 verifier()->verify_before_updaterefs();
2130 }
2131
2132 set_update_refs_in_progress(true);
2133
2134 {
2135 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_prepare);
2136
2137 make_parsable(true);
2138
2139 // Reset iterator.
2140 _update_refs_iterator.reset();
2141 }
2142
2143 if (ShenandoahPacing) {
2144 pacer()->setup_for_updaterefs();
2145 }
2146 }
2147
2148 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2149 private:
2150 ShenandoahHeapLock* const _lock;
2151
2152 public:
2153 ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2154
2155 void heap_region_do(ShenandoahHeapRegion* r) {
2156 // Drop unnecessary "pinned" state from regions that does not have CP marks
2157 // anymore, as this would allow trashing them.
2158
2159 if (r->is_active()) {
2160 if (r->is_pinned()) {
2161 if (r->pin_count() == 0) {
2162 ShenandoahHeapLocker locker(_lock);
2163 r->make_unpinned();
2164 }
2165 } else {
2166 if (r->pin_count() > 0) {
2167 ShenandoahHeapLocker locker(_lock);
2168 r->make_pinned();
2169 }
2170 }
2171 }
2172 }
2173
2174 bool is_thread_safe() { return true; }
2175 };
2176
2177 void ShenandoahHeap::op_final_updaterefs() {
2178 assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
2179
2180 // Check if there is left-over work, and finish it
2181 if (_update_refs_iterator.has_next()) {
2182 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
2183
2184 // Finish updating references where we left off.
2185 clear_cancelled_gc();
2186 update_heap_references(false);
2187 }
2188
2189 // Clear cancelled GC, if set. On cancellation path, the block before would handle
2190 // everything. On degenerated paths, cancelled gc would not be set anyway.
2191 if (cancelled_gc()) {
2192 clear_cancelled_gc();
2193 }
2194 assert(!cancelled_gc(), "Should have been done right before");
2195
2196 if (ShenandoahVerify && !is_degenerated_gc_in_progress()) {
2197 verifier()->verify_roots_no_forwarded_except(ShenandoahRootVerifier::ThreadRoots);
2198 }
2199
2200 if (is_degenerated_gc_in_progress()) {
2201 concurrent_mark()->update_roots(ShenandoahPhaseTimings::degen_gc_update_roots);
2202 } else {
2203 concurrent_mark()->update_thread_roots(ShenandoahPhaseTimings::final_update_refs_roots);
2204 }
2205
2206 // Has to be done before cset is clear
2207 if (ShenandoahVerify) {
2208 verifier()->verify_roots_in_to_space();
2209 }
2210
2211 {
2212 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
2213 trash_cset_regions();
2214 }
2215
2216 set_has_forwarded_objects(false);
2217 set_update_refs_in_progress(false);
2218
2219 if (ShenandoahVerify) {
2220 verifier()->verify_after_updaterefs();
2221 }
2222
2223 if (VerifyAfterGC) {
2224 Universe::verify();
2225 }
2226
2227 {
2228 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_update_region_states);
2229 ShenandoahFinalUpdateRefsUpdateRegionStateClosure cl;
2230 parallel_heap_region_iterate(&cl);
2231
2232 assert_pinned_region_status();
2233 }
2234
2235 {
2236 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_rebuild_freeset);
2237 ShenandoahHeapLocker locker(lock());
2238 _free_set->rebuild();
2239 }
2240 }
2241
2242 void ShenandoahHeap::print_extended_on(outputStream *st) const {
2243 print_on(st);
2244 print_heap_regions_on(st);
2245 }
2246
2247 bool ShenandoahHeap::is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self) {
2248 size_t slice = r->index() / _bitmap_regions_per_slice;
2249
2250 size_t regions_from = _bitmap_regions_per_slice * slice;
2251 size_t regions_to = MIN2(num_regions(), _bitmap_regions_per_slice * (slice + 1));
2252 for (size_t g = regions_from; g < regions_to; g++) {
2253 assert (g / _bitmap_regions_per_slice == slice, "same slice");
2254 if (skip_self && g == r->index()) continue;
2255 if (get_region(g)->is_committed()) {
2256 return true;
2257 }
2258 }
2259 return false;
2260 }
2261
2262 bool ShenandoahHeap::commit_bitmap_slice(ShenandoahHeapRegion* r) {
2263 shenandoah_assert_heaplocked();
2264
2265 // Bitmaps in special regions do not need commits
2266 if (_bitmap_region_special) {
2267 return true;
2268 }
2269
2270 if (is_bitmap_slice_committed(r, true)) {
2271 // Some other region from the group is already committed, meaning the bitmap
2272 // slice is already committed, we exit right away.
2273 return true;
2274 }
2275
2276 // Commit the bitmap slice:
2277 size_t slice = r->index() / _bitmap_regions_per_slice;
2278 size_t off = _bitmap_bytes_per_slice * slice;
2279 size_t len = _bitmap_bytes_per_slice;
2280 char* start = (char*) _bitmap_region.start() + off;
2281
2282 if (!os::commit_memory(start, len, false)) {
2283 return false;
2284 }
2285
2286 if (AlwaysPreTouch) {
2287 os::pretouch_memory(start, start + len);
2288 }
2289
2290 return true;
2291 }
2292
2293 bool ShenandoahHeap::uncommit_bitmap_slice(ShenandoahHeapRegion *r) {
2294 shenandoah_assert_heaplocked();
2295
2296 // Bitmaps in special regions do not need uncommits
2297 if (_bitmap_region_special) {
2298 return true;
2299 }
2300
2301 if (is_bitmap_slice_committed(r, true)) {
2302 // Some other region from the group is still committed, meaning the bitmap
2303 // slice is should stay committed, exit right away.
2304 return true;
2305 }
2306
2307 // Uncommit the bitmap slice:
2308 size_t slice = r->index() / _bitmap_regions_per_slice;
2309 size_t off = _bitmap_bytes_per_slice * slice;
2310 size_t len = _bitmap_bytes_per_slice;
2311 if (!os::uncommit_memory((char*)_bitmap_region.start() + off, len)) {
2312 return false;
2313 }
2314 return true;
2315 }
2316
2317 void ShenandoahHeap::vmop_entry_init_mark() {
2318 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2319 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark_gross);
2320
2321 try_inject_alloc_failure();
2322 VM_ShenandoahInitMark op;
2323 VMThread::execute(&op); // jump to entry_init_mark() under safepoint
2324 }
2325
2326 void ShenandoahHeap::vmop_entry_final_mark() {
2327 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2328 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark_gross);
2329
2330 try_inject_alloc_failure();
2331 VM_ShenandoahFinalMarkStartEvac op;
2332 VMThread::execute(&op); // jump to entry_final_mark under safepoint
2333 }
2334
2335 void ShenandoahHeap::vmop_entry_init_updaterefs() {
2336 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2337 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_gross);
2338
2339 try_inject_alloc_failure();
2340 VM_ShenandoahInitUpdateRefs op;
2341 VMThread::execute(&op);
2342 }
2343
2344 void ShenandoahHeap::vmop_entry_final_updaterefs() {
2345 TraceCollectorStats tcs(monitoring_support()->stw_collection_counters());
2346 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_gross);
2347
2348 try_inject_alloc_failure();
2349 VM_ShenandoahFinalUpdateRefs op;
2350 VMThread::execute(&op);
2351 }
2352
2353 void ShenandoahHeap::vmop_entry_full(GCCause::Cause cause) {
2354 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2355 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_gross);
2356
2357 try_inject_alloc_failure();
2358 VM_ShenandoahFullGC op(cause);
2359 VMThread::execute(&op);
2360 }
2361
2362 void ShenandoahHeap::vmop_degenerated(ShenandoahDegenPoint point) {
2363 TraceCollectorStats tcs(monitoring_support()->full_stw_collection_counters());
2364 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc_gross);
2365
2366 VM_ShenandoahDegeneratedGC degenerated_gc((int)point);
2367 VMThread::execute(°enerated_gc);
2368 }
2369
2370 void ShenandoahHeap::entry_init_mark() {
2371 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_mark);
2372
2373 const char* msg = init_mark_event_message();
2374 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2375 EventMark em("%s", msg);
2376
2377 ShenandoahWorkerScope scope(workers(),
2378 ShenandoahWorkerPolicy::calc_workers_for_init_marking(),
2379 "init marking");
2380
2381 op_init_mark();
2382 }
2383
2384 void ShenandoahHeap::entry_final_mark() {
2385 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_mark);
2386
2387 const char* msg = final_mark_event_message();
2388 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2389 EventMark em("%s", msg);
2390
2391 ShenandoahWorkerScope scope(workers(),
2392 ShenandoahWorkerPolicy::calc_workers_for_final_marking(),
2393 "final marking");
2394
2395 op_final_mark();
2396 }
2397
2398 void ShenandoahHeap::entry_init_updaterefs() {
2399 ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs);
2400
2401 static const char* msg = "Pause Init Update Refs";
2402 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id());
2403 EventMark em("%s", msg);
2404
2405 // No workers used in this phase, no setup required
2406
2407 op_init_updaterefs();
2408 }
2409
2410 void ShenandoahHeap::entry_final_updaterefs() {
2411 ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs);
2412
2413 static const char* msg = "Pause Final Update Refs";
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_update_ref(),
2419 "final reference update");
2420
2421 op_final_updaterefs();
2422 }
2423
2424 void ShenandoahHeap::entry_full(GCCause::Cause cause) {
2425 ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc);
2426
2427 static const char* msg = "Pause Full";
2428 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id(), true);
2429 EventMark em("%s", msg);
2430
2431 ShenandoahWorkerScope scope(workers(),
2432 ShenandoahWorkerPolicy::calc_workers_for_fullgc(),
2433 "full gc");
2434
2435 op_full(cause);
2436 }
2437
2438 void ShenandoahHeap::entry_degenerated(int point) {
2439 ShenandoahGCPhase phase(ShenandoahPhaseTimings::degen_gc);
2440
2441 ShenandoahDegenPoint dpoint = (ShenandoahDegenPoint)point;
2442 const char* msg = degen_event_message(dpoint);
2443 GCTraceTime time(msg, PrintGC, _gc_timer, tracer()->gc_id(), true);
2444 EventMark em("%s", msg);
2445
2446 ShenandoahWorkerScope scope(workers(),
2447 ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated(),
2448 "stw degenerated gc");
2449
2450 set_degenerated_gc_in_progress(true);
2451 op_degenerated(dpoint);
2452 set_degenerated_gc_in_progress(false);
2453 }
2454
2455 void ShenandoahHeap::entry_mark() {
2456 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2457
2458 const char* msg = conc_mark_event_message();
2459 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id());
2460 EventMark em("%s", msg);
2461
2462 ShenandoahWorkerScope scope(workers(),
2463 ShenandoahWorkerPolicy::calc_workers_for_conc_marking(),
2464 "concurrent marking");
2465
2466 try_inject_alloc_failure();
2467 op_mark();
2468 }
2469
2470 void ShenandoahHeap::entry_evac() {
2471 ShenandoahGCPhase conc_evac_phase(ShenandoahPhaseTimings::conc_evac);
2472 TraceCollectorStats tcs(monitoring_support()->concurrent_collection_counters());
2473
2474 static const char *msg = "Concurrent evacuation";
2475 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id());
2476 EventMark em("%s", msg);
2477
2478 ShenandoahWorkerScope scope(workers(),
2479 ShenandoahWorkerPolicy::calc_workers_for_conc_evac(),
2480 "concurrent evacuation");
2481
2482 try_inject_alloc_failure();
2483 op_conc_evac();
2484 }
2485
2486 void ShenandoahHeap::entry_updaterefs() {
2487 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_update_refs);
2488
2489 static const char* msg = "Concurrent update references";
2490 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id());
2491 EventMark em("%s", msg);
2492
2493 ShenandoahWorkerScope scope(workers(),
2494 ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref(),
2495 "concurrent reference update");
2496
2497 try_inject_alloc_failure();
2498 op_updaterefs();
2499 }
2500
2501 void ShenandoahHeap::entry_cleanup_early() {
2502 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup_early);
2503
2504 static const char* msg = "Concurrent cleanup";
2505 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2506 EventMark em("%s", msg);
2507
2508 // This phase does not use workers, no need for setup
2509
2510 try_inject_alloc_failure();
2511 op_cleanup_early();
2512 }
2513
2514 void ShenandoahHeap::entry_cleanup_complete() {
2515 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_cleanup_complete);
2516
2517 static const char* msg = "Concurrent cleanup";
2518 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2519 EventMark em("%s", msg);
2520
2521 // This phase does not use workers, no need for setup
2522
2523 try_inject_alloc_failure();
2524 op_cleanup_complete();
2525 }
2526
2527 void ShenandoahHeap::entry_reset() {
2528 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_reset);
2529
2530 static const char* msg = "Concurrent reset";
2531 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id());
2532 EventMark em("%s", msg);
2533
2534 ShenandoahWorkerScope scope(workers(),
2535 ShenandoahWorkerPolicy::calc_workers_for_conc_reset(),
2536 "concurrent reset");
2537
2538 try_inject_alloc_failure();
2539 op_reset();
2540 }
2541
2542 void ShenandoahHeap::entry_preclean() {
2543 if (ShenandoahPreclean && process_references()) {
2544 ShenandoahGCPhase conc_preclean(ShenandoahPhaseTimings::conc_preclean);
2545
2546 static const char* msg = "Concurrent precleaning";
2547 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id());
2548 EventMark em("%s", msg);
2549
2550 ShenandoahWorkerScope scope(workers(),
2551 ShenandoahWorkerPolicy::calc_workers_for_conc_preclean(),
2552 "concurrent preclean",
2553 /* check_workers = */ false);
2554
2555 try_inject_alloc_failure();
2556 op_preclean();
2557 }
2558 }
2559
2560 void ShenandoahHeap::entry_uncommit(double shrink_before) {
2561 static const char *msg = "Concurrent uncommit";
2562 GCTraceTime time(msg, PrintGC, NULL, tracer()->gc_id(), true);
2563 EventMark em("%s", msg);
2564
2565 ShenandoahGCPhase phase(ShenandoahPhaseTimings::conc_uncommit);
2566
2567 op_uncommit(shrink_before);
2568 }
2569
2570 void ShenandoahHeap::try_inject_alloc_failure() {
2571 if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2572 _inject_alloc_failure.set();
2573 os::naked_short_sleep(1);
2574 if (cancelled_gc()) {
2575 log_info(gc)("Allocation failure was successfully injected");
2576 }
2577 }
2578 }
2579
2580 bool ShenandoahHeap::should_inject_alloc_failure() {
2581 return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2582 }
2583
2584 void ShenandoahHeap::enter_evacuation() {
2585 _oom_evac_handler.enter_evacuation();
2586 }
2587
2588 void ShenandoahHeap::leave_evacuation() {
2589 _oom_evac_handler.leave_evacuation();
2590 }
2591
2592 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2593 _heap(ShenandoahHeap::heap()),
2594 _index(0) {}
2595
2596 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2597 _heap(heap),
2598 _index(0) {}
2599
2600 void ShenandoahRegionIterator::reset() {
2601 _index = 0;
2602 }
2603
2604 bool ShenandoahRegionIterator::has_next() const {
2605 return _index < (jint)_heap->num_regions();
2606 }
2607
2608 char ShenandoahHeap::gc_state() {
2609 return _gc_state.raw_value();
2610 }
2611
2612 const char* ShenandoahHeap::init_mark_event_message() const {
2613 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
2614
2615 bool proc_refs = process_references();
2616 bool unload_cls = unload_classes();
2617
2618 if (proc_refs && unload_cls) {
2619 return "Pause Init Mark (process weakrefs) (unload classes)";
2620 } else if (proc_refs) {
2621 return "Pause Init Mark (process weakrefs)";
2622 } else if (unload_cls) {
2623 return "Pause Init Mark (unload classes)";
2624 } else {
2625 return "Pause Init Mark";
2626 }
2627 }
2628
2629 const char* ShenandoahHeap::final_mark_event_message() const {
2630 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
2631
2632 bool proc_refs = process_references();
2633 bool unload_cls = unload_classes();
2634
2635 if (proc_refs && unload_cls) {
2636 return "Pause Final Mark (process weakrefs) (unload classes)";
2637 } else if (proc_refs) {
2638 return "Pause Final Mark (process weakrefs)";
2639 } else if (unload_cls) {
2640 return "Pause Final Mark (unload classes)";
2641 } else {
2642 return "Pause Final Mark";
2643 }
2644 }
2645
2646 const char* ShenandoahHeap::conc_mark_event_message() const {
2647 assert(!has_forwarded_objects(), "Should not have forwarded objects here");
2648
2649 bool proc_refs = process_references();
2650 bool unload_cls = unload_classes();
2651
2652 if (proc_refs && unload_cls) {
2653 return "Concurrent marking (process weakrefs) (unload classes)";
2654 } else if (proc_refs) {
2655 return "Concurrent marking (process weakrefs)";
2656 } else if (unload_cls) {
2657 return "Concurrent marking (unload classes)";
2658 } else {
2659 return "Concurrent marking";
2660 }
2661 }
2662
2663 const char* ShenandoahHeap::degen_event_message(ShenandoahDegenPoint point) const {
2664 switch (point) {
2665 case _degenerated_unset:
2666 return "Pause Degenerated GC (<UNSET>)";
2667 case _degenerated_outside_cycle:
2668 return "Pause Degenerated GC (Outside of Cycle)";
2669 case _degenerated_mark:
2670 return "Pause Degenerated GC (Mark)";
2671 case _degenerated_evac:
2672 return "Pause Degenerated GC (Evacuation)";
2673 case _degenerated_updaterefs:
2674 return "Pause Degenerated GC (Update Refs)";
2675 default:
2676 ShouldNotReachHere();
2677 return "ERROR";
2678 }
2679 }
2680
2681 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2682 #ifdef ASSERT
2683 assert(_liveness_cache != NULL, "sanity");
2684 assert(worker_id < _max_workers, "sanity");
2685 for (uint i = 0; i < num_regions(); i++) {
2686 assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2687 }
2688 #endif
2689 return _liveness_cache[worker_id];
2690 }
2691
2692 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2693 assert(worker_id < _max_workers, "sanity");
2694 assert(_liveness_cache != NULL, "sanity");
2695 ShenandoahLiveData* ld = _liveness_cache[worker_id];
2696 for (uint i = 0; i < num_regions(); i++) {
2697 ShenandoahLiveData live = ld[i];
2698 if (live > 0) {
2699 ShenandoahHeapRegion* r = get_region(i);
2700 r->increase_live_data_gc_words(live);
2701 ld[i] = 0;
2702 }
2703 }
2704 }