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/*
* Copyright (c) 2015, 2020, Red Hat, Inc. All rights reserved.
+ * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
#include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"
#include "gc/shenandoah/shenandoahForwarding.inline.hpp"
#include "gc/shenandoah/shenandoahWorkGroup.hpp"
#include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"
#include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
! #include "gc/shenandoah/shenandoahControlThread.hpp"
#include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
#include "gc/shenandoah/shenandoahThreadLocalData.hpp"
#include "oops/compressedOops.inline.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/atomic.hpp"
#include "runtime/javaThread.hpp"
#include "runtime/prefetch.inline.hpp"
#include "utilities/copy.hpp"
#include "utilities/globalDefinitions.hpp"
inline ShenandoahHeap* ShenandoahHeap::heap() {
return named_heap<ShenandoahHeap>(CollectedHeap::Shenandoah);
#include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"
#include "gc/shenandoah/shenandoahForwarding.inline.hpp"
#include "gc/shenandoah/shenandoahWorkGroup.hpp"
#include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"
#include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
! #include "gc/shenandoah/shenandoahGeneration.hpp"
#include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
#include "gc/shenandoah/shenandoahThreadLocalData.hpp"
+ #include "gc/shenandoah/mode/shenandoahMode.hpp"
#include "oops/compressedOops.inline.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/atomic.hpp"
#include "runtime/javaThread.hpp"
#include "runtime/prefetch.inline.hpp"
+ #include "runtime/objectMonitor.inline.hpp"
#include "utilities/copy.hpp"
#include "utilities/globalDefinitions.hpp"
inline ShenandoahHeap* ShenandoahHeap::heap() {
return named_heap<ShenandoahHeap>(CollectedHeap::Shenandoah);
inline WorkerThreads* ShenandoahHeap::safepoint_workers() {
return _safepoint_workers;
}
inline size_t ShenandoahHeap::heap_region_index_containing(const void* addr) const {
uintptr_t region_start = ((uintptr_t) addr);
uintptr_t index = (region_start - (uintptr_t) base()) >> ShenandoahHeapRegion::region_size_bytes_shift();
assert(index < num_regions(), "Region index is in bounds: " PTR_FORMAT, p2i(addr));
return index;
}
! inline ShenandoahHeapRegion* const ShenandoahHeap::heap_region_containing(const void* addr) const {
size_t index = heap_region_index_containing(addr);
ShenandoahHeapRegion* const result = get_region(index);
assert(addr >= result->bottom() && addr < result->end(), "Heap region contains the address: " PTR_FORMAT, p2i(addr));
return result;
}
inline WorkerThreads* ShenandoahHeap::safepoint_workers() {
return _safepoint_workers;
}
+ inline void ShenandoahHeap::notify_gc_progress() {
+ Atomic::store(&_gc_no_progress_count, (size_t) 0);
+
+ }
+ inline void ShenandoahHeap::notify_gc_no_progress() {
+ Atomic::inc(&_gc_no_progress_count);
+ }
+
+ inline size_t ShenandoahHeap::get_gc_no_progress_count() const {
+ return Atomic::load(&_gc_no_progress_count);
+ }
+
inline size_t ShenandoahHeap::heap_region_index_containing(const void* addr) const {
uintptr_t region_start = ((uintptr_t) addr);
uintptr_t index = (region_start - (uintptr_t) base()) >> ShenandoahHeapRegion::region_size_bytes_shift();
assert(index < num_regions(), "Region index is in bounds: " PTR_FORMAT, p2i(addr));
return index;
}
! inline ShenandoahHeapRegion* ShenandoahHeap::heap_region_containing(const void* addr) const {
size_t index = heap_region_index_containing(addr);
ShenandoahHeapRegion* const result = get_region(index);
assert(addr >= result->bottom() && addr < result->end(), "Heap region contains the address: " PTR_FORMAT, p2i(addr));
return result;
}
}
}
return cancelled_gc();
}
! inline void ShenandoahHeap::clear_cancelled_gc() {
_cancelled_gc.set(CANCELLABLE);
! _oom_evac_handler.clear();
}
inline HeapWord* ShenandoahHeap::allocate_from_gclab(Thread* thread, size_t size) {
assert(UseTLAB, "TLABs should be enabled");
}
}
return cancelled_gc();
}
! inline void ShenandoahHeap::clear_cancelled_gc(bool clear_oom_handler) {
_cancelled_gc.set(CANCELLABLE);
! if (_cancel_requested_time > 0) {
+ log_debug(gc)("GC cancellation took %.3fs", (os::elapsedTime() - _cancel_requested_time));
+ _cancel_requested_time = 0;
+ }
+
+ if (clear_oom_handler) {
+ _oom_evac_handler.clear();
+ }
}
inline HeapWord* ShenandoahHeap::allocate_from_gclab(Thread* thread, size_t size) {
assert(UseTLAB, "TLABs should be enabled");
}
HeapWord* obj = gclab->allocate(size);
if (obj != nullptr) {
return obj;
}
- // Otherwise...
return allocate_from_gclab_slow(thread, size);
}
! inline oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {
! if (ShenandoahThreadLocalData::is_oom_during_evac(Thread::current())) {
! // This thread went through the OOM during evac protocol and it is safe to return
! // the forward pointer. It must not attempt to evacuate any more.
! return ShenandoahBarrierSet::resolve_forwarded(p);
}
! assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope");
! size_t size = p->size();
! assert(!heap_region_containing(p)->is_humongous(), "never evacuate humongous objects");
! bool alloc_from_gclab = true;
- HeapWord* copy = nullptr;
! #ifdef ASSERT
! if (ShenandoahOOMDuringEvacALot &&
! (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call
! copy = nullptr;
- } else {
- #endif
- if (UseTLAB) {
- copy = allocate_from_gclab(thread, size);
- }
- if (copy == nullptr) {
- ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size);
- copy = allocate_memory(req);
- alloc_from_gclab = false;
- }
- #ifdef ASSERT
}
- #endif
! if (copy == nullptr) {
! control_thread()->handle_alloc_failure_evac(size);
! _oom_evac_handler.handle_out_of_memory_during_evacuation();
! return ShenandoahBarrierSet::resolve_forwarded(p);
! }
! // Copy the object:
! Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(p), copy, size);
!
! // Try to install the new forwarding pointer.
! oop copy_val = cast_to_oop(copy);
! ContinuationGCSupport::relativize_stack_chunk(copy_val);
!
! oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val);
! if (result == copy_val) {
! // Successfully evacuated. Our copy is now the public one!
! shenandoah_assert_correct(nullptr, copy_val);
! return copy_val;
! } else {
! // Failed to evacuate. We need to deal with the object that is left behind. Since this
! // new allocation is certainly after TAMS, it will be considered live in the next cycle.
! // But if it happens to contain references to evacuated regions, those references would
! // not get updated for this stale copy during this cycle, and we will crash while scanning
! // it the next cycle.
! //
! // For GCLAB allocations, it is enough to rollback the allocation ptr. Either the next
! // object will overwrite this stale copy, or the filler object on LAB retirement will
! // do this. For non-GCLAB allocations, we have no way to retract the allocation, and
- // have to explicitly overwrite the copy with the filler object. With that overwrite,
- // we have to keep the fwdptr initialized and pointing to our (stale) copy.
- if (alloc_from_gclab) {
- ShenandoahThreadLocalData::gclab(thread)->undo_allocation(copy, size);
- } else {
- fill_with_object(copy, size);
- shenandoah_assert_correct(nullptr, copy_val);
- }
- shenandoah_assert_correct(nullptr, result);
- return result;
}
}
inline bool ShenandoahHeap::requires_marking(const void* entry) const {
oop obj = cast_to_oop(entry);
return !_marking_context->is_marked_strong(obj);
}
}
HeapWord* obj = gclab->allocate(size);
if (obj != nullptr) {
return obj;
}
return allocate_from_gclab_slow(thread, size);
}
! void ShenandoahHeap::increase_object_age(oop obj, uint additional_age) {
! // This operates on new copy of an object. This means that the object's mark-word
! // is thread-local and therefore safe to access. However, when the mark is
! // displaced (i.e. stack-locked or monitor-locked), then it must be considered
! // a shared memory location. It can be accessed by other threads.
+ // In particular, a competing evacuating thread can succeed to install its copy
+ // as the forwardee and continue to unlock the object, at which point 'our'
+ // write to the foreign stack-location would potentially over-write random
+ // information on that stack. Writing to a monitor is less problematic,
+ // but still not safe: while the ObjectMonitor would not randomly disappear,
+ // the other thread would also write to the same displaced header location,
+ // possibly leading to increase the age twice.
+ // For all these reasons, we take the conservative approach and not attempt
+ // to increase the age when the header is displaced.
+ markWord w = obj->mark();
+ // The mark-word has been copied from the original object. It can not be
+ // inflating, because inflation can not be interrupted by a safepoint,
+ // and after a safepoint, a Java thread would first have to successfully
+ // evacuate the object before it could inflate the monitor.
+ assert(!w.is_being_inflated() || LockingMode == LM_LIGHTWEIGHT, "must not inflate monitor before evacuation of object succeeds");
+ // It is possible that we have copied the object after another thread has
+ // already successfully completed evacuation. While harmless (we would never
+ // publish our copy), don't even attempt to modify the age when that
+ // happens.
+ if (!w.has_displaced_mark_helper() && !w.is_marked()) {
+ w = w.set_age(MIN2(markWord::max_age, w.age() + additional_age));
+ obj->set_mark(w);
}
+ }
! // Return the object's age, or a sentinel value when the age can't
+ // necessarily be determined because of concurrent locking by the
+ // mutator
+ uint ShenandoahHeap::get_object_age(oop obj) {
+ markWord w = obj->mark();
+ assert(!w.is_marked(), "must not be forwarded");
+ if (w.has_monitor()) {
+ w = w.monitor()->header();
+ } else if (w.is_being_inflated() || w.has_displaced_mark_helper()) {
+ // Informs caller that we aren't able to determine the age
+ return markWord::max_age + 1; // sentinel
+ }
+ assert(w.age() <= markWord::max_age, "Impossible!");
+ return w.age();
+ }
! bool ShenandoahHeap::is_in(const void* p) const {
+ HeapWord* heap_base = (HeapWord*) base();
+ HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
+ return p >= heap_base && p < last_region_end;
+ }
! inline bool ShenandoahHeap::is_in_active_generation(oop obj) const {
+ if (!mode()->is_generational()) {
+ // everything is the same single generation
+ assert(is_in(obj), "Otherwise shouldn't return true below");
+ return true;
+ }
! ShenandoahGeneration* const gen = active_generation();
! if (gen == nullptr) {
! // no collection is happening: only expect this to be called
! // when concurrent processing is active, but that could change
! return false;
}
! assert(is_in(obj), "only check if is in active generation for objects (" PTR_FORMAT ") in heap", p2i(obj));
! assert(gen->is_old() || gen->is_young() || gen->is_global(),
+ "Active generation must be old, young, or global");
+
+ size_t index = heap_region_containing(obj)->index();
+
+ // No flickering!
+ assert(gen == active_generation(), "Race?");
+
+ switch (_affiliations[index]) {
+ case ShenandoahAffiliation::FREE:
+ // Free regions are in old, young, and global collections
+ return true;
+ case ShenandoahAffiliation::YOUNG_GENERATION:
+ // Young regions are in young and global collections, not in old collections
+ return !gen->is_old();
+ case ShenandoahAffiliation::OLD_GENERATION:
+ // Old regions are in old and global collections, not in young collections
+ return !gen->is_young();
+ default:
+ assert(false, "Bad affiliation (%d) for region " SIZE_FORMAT, _affiliations[index], index);
+ return false;
+ }
+ }
+
+ inline bool ShenandoahHeap::is_in_young(const void* p) const {
+ return is_in(p) && (_affiliations[heap_region_index_containing(p)] == ShenandoahAffiliation::YOUNG_GENERATION);
+ }
! inline bool ShenandoahHeap::is_in_old(const void* p) const {
+ return is_in(p) && (_affiliations[heap_region_index_containing(p)] == ShenandoahAffiliation::OLD_GENERATION);
+ }
! inline bool ShenandoahHeap::is_in_old_during_young_collection(oop obj) const {
! return active_generation()->is_young() && is_in_old(obj);
+ }
! inline ShenandoahAffiliation ShenandoahHeap::region_affiliation(const ShenandoahHeapRegion *r) {
! return (ShenandoahAffiliation) _affiliations[r->index()];
! }
!
! inline void ShenandoahHeap::assert_lock_for_affiliation(ShenandoahAffiliation orig_affiliation,
! ShenandoahAffiliation new_affiliation) {
! // A lock is required when changing from FREE to NON-FREE. Though it may be possible to elide the lock when
! // transitioning from in-use to FREE, the current implementation uses a lock for this transition. A lock is
! // not required to change from YOUNG to OLD (i.e. when promoting humongous region).
! //
! // new_affiliation is: FREE YOUNG OLD
! // orig_affiliation is: FREE X L L
! // YOUNG L X
! // OLD L X X
! // X means state transition won't happen (so don't care)
! // L means lock should be held
! // Blank means no lock required because affiliation visibility will not be required until subsequent safepoint
! //
! // Note: during full GC, all transitions between states are possible. During Full GC, we should be in a safepoint.
!
! if ((orig_affiliation == ShenandoahAffiliation::FREE) || (new_affiliation == ShenandoahAffiliation::FREE)) {
! shenandoah_assert_heaplocked_or_safepoint();
}
}
+ inline void ShenandoahHeap::set_affiliation(ShenandoahHeapRegion* r, ShenandoahAffiliation new_affiliation) {
+ #ifdef ASSERT
+ assert_lock_for_affiliation(region_affiliation(r), new_affiliation);
+ #endif
+ _affiliations[r->index()] = (uint8_t) new_affiliation;
+ }
+
+ inline ShenandoahAffiliation ShenandoahHeap::region_affiliation(size_t index) {
+ return (ShenandoahAffiliation) _affiliations[index];
+ }
+
inline bool ShenandoahHeap::requires_marking(const void* entry) const {
oop obj = cast_to_oop(entry);
return !_marking_context->is_marked_strong(obj);
}
inline bool ShenandoahHeap::is_concurrent_mark_in_progress() const {
return _gc_state.is_set(MARKING);
}
+ inline bool ShenandoahHeap::is_concurrent_young_mark_in_progress() const {
+ return _gc_state.is_set(YOUNG_MARKING);
+ }
+
+ inline bool ShenandoahHeap::is_concurrent_old_mark_in_progress() const {
+ return _gc_state.is_set(OLD_MARKING);
+ }
+
inline bool ShenandoahHeap::is_evacuation_in_progress() const {
return _gc_state.is_set(EVACUATION);
}
inline bool ShenandoahHeap::is_degenerated_gc_in_progress() const {
template<class T>
inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit) {
assert(! region->is_humongous_continuation(), "no humongous continuation regions here");
! ShenandoahMarkingContext* const ctx = complete_marking_context();
- assert(ctx->is_complete(), "sanity");
HeapWord* tams = ctx->top_at_mark_start(region);
size_t skip_bitmap_delta = 1;
HeapWord* start = region->bottom();
template<class T>
inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit) {
assert(! region->is_humongous_continuation(), "no humongous continuation regions here");
! ShenandoahMarkingContext* const ctx = marking_context();
HeapWord* tams = ctx->top_at_mark_start(region);
size_t skip_bitmap_delta = 1;
HeapWord* start = region->bottom();
ShenandoahObjectToOopClosure<T> objs(cl);
marked_object_iterate(region, &objs, top);
}
}
! inline ShenandoahHeapRegion* const ShenandoahHeap::get_region(size_t region_idx) const {
if (region_idx < _num_regions) {
return _regions[region_idx];
} else {
return nullptr;
}
}
- inline void ShenandoahHeap::mark_complete_marking_context() {
- _marking_context->mark_complete();
- }
-
- inline void ShenandoahHeap::mark_incomplete_marking_context() {
- _marking_context->mark_incomplete();
- }
-
inline ShenandoahMarkingContext* ShenandoahHeap::complete_marking_context() const {
assert (_marking_context->is_complete()," sanity");
return _marking_context;
}
ShenandoahObjectToOopClosure<T> objs(cl);
marked_object_iterate(region, &objs, top);
}
}
! inline ShenandoahHeapRegion* ShenandoahHeap::get_region(size_t region_idx) const {
if (region_idx < _num_regions) {
return _regions[region_idx];
} else {
return nullptr;
}
}
inline ShenandoahMarkingContext* ShenandoahHeap::complete_marking_context() const {
assert (_marking_context->is_complete()," sanity");
return _marking_context;
}
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