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7080389: G1: refactor marking code in evacuation pause copy closures

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Refactor code marking code in the evacuation pause copy closures so that an evacuated object is only marked by the thread that successfully copies it.

Reviewed-by: stefank, brutisso, tonyp
This commit is contained in:
John Cuthbertson 2011-08-29 10:13:06 -07:00
parent 06d05b7c47
commit 1bec3a1bd3
4 changed files with 81 additions and 29 deletions
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82
hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp
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@ -4069,6 +4069,23 @@ bool GCLabBitMapClosure::do_bit(size_t offset) {
}
#endif // PRODUCT
G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
ParGCAllocBuffer(gclab_word_size),
_should_mark_objects(false),
_bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
_retired(false)
{
//_should_mark_objects is set to true when G1ParCopyHelper needs to
// mark the forwarded location of an evacuated object.
// We set _should_mark_objects to true if marking is active, i.e. when we
// need to propagate a mark, or during an initial mark pause, i.e. when we
// need to mark objects immediately reachable by the roots.
if (G1CollectedHeap::heap()->mark_in_progress() ||
G1CollectedHeap::heap()->g1_policy()->during_initial_mark_pause()) {
_should_mark_objects = true;
}
}
G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
: _g1h(g1h),
_refs(g1h->task_queue(queue_num)),
@ -4184,12 +4201,14 @@ void G1ParScanThreadState::trim_queue() {
G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
_g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
_par_scan_state(par_scan_state) { }
_par_scan_state(par_scan_state),
_during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
_mark_in_progress(_g1->mark_in_progress()) { }
template <class T> void G1ParCopyHelper::mark_forwardee(T* p) {
// This is called _after_ do_oop_work has been called, hence after
// the object has been relocated to its new location and *p points
// to its new location.
template <class T> void G1ParCopyHelper::mark_object(T* p) {
// This is called from do_oop_work for objects that are not
// in the collection set. Objects in the collection set
// are marked after they have been evacuated.
T heap_oop = oopDesc::load_heap_oop(p);
if (!oopDesc::is_null(heap_oop)) {
@ -4201,7 +4220,7 @@ template <class T> void G1ParCopyHelper::mark_forwardee(T* p) {
}
}
oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
oop G1ParCopyHelper::copy_to_survivor_space(oop old, bool should_mark_copy) {
size_t word_sz = old->size();
HeapRegion* from_region = _g1->heap_region_containing_raw(old);
// +1 to make the -1 indexes valid...
@ -4257,8 +4276,8 @@ oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
obj->set_mark(m);
}
// preserve "next" mark bit
if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
// Mark the evacuated object or propagate "next" mark bit
if (should_mark_copy) {
if (!use_local_bitmaps ||
!_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
// if we couldn't mark it on the local bitmap (this happens when
@ -4266,11 +4285,12 @@ oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
// the bullet and do the standard parallel mark
_cm->markAndGrayObjectIfNecessary(obj);
}
#if 1
if (_g1->isMarkedNext(old)) {
// Unmark the object's old location so that marking
// doesn't think the old object is alive.
_cm->nextMarkBitMap()->parClear((HeapWord*)old);
}
#endif
}
size_t* surv_young_words = _par_scan_state->surviving_young_words();
@ -4293,26 +4313,62 @@ oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
return obj;
}
template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee>
template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
template <class T>
void G1ParCopyClosure <do_gen_barrier, barrier, do_mark_forwardee>
void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
::do_oop_work(T* p) {
oop obj = oopDesc::load_decode_heap_oop(p);
assert(barrier != G1BarrierRS || obj != NULL,
"Precondition: G1BarrierRS implies obj is nonNull");
// Marking:
// If the object is in the collection set, then the thread
// that copies the object should mark, or propagate the
// mark to, the evacuated object.
// If the object is not in the collection set then we
// should call the mark_object() method depending on the
// value of the template parameter do_mark_object (which will
// be true for root scanning closures during an initial mark
// pause).
// The mark_object() method first checks whether the object
// is marked and, if not, attempts to mark the object.
// here the null check is implicit in the cset_fast_test() test
if (_g1->in_cset_fast_test(obj)) {
if (obj->is_forwarded()) {
oopDesc::encode_store_heap_oop(p, obj->forwardee());
// If we are a root scanning closure during an initial
// mark pause (i.e. do_mark_object will be true) then
// we also need to handle marking of roots in the
// event of an evacuation failure. In the event of an
// evacuation failure, the object is forwarded to itself
// and not copied so let's mark it here.
if (do_mark_object && obj->forwardee() == obj) {
mark_object(p);
}
} else {
oop copy_oop = copy_to_survivor_space(obj);
// We need to mark the copied object if we're a root scanning
// closure during an initial mark pause (i.e. do_mark_object
// will be true), or the object is already marked and we need
// to propagate the mark to the evacuated copy.
bool should_mark_copy = do_mark_object ||
_during_initial_mark ||
(_mark_in_progress && !_g1->is_obj_ill(obj));
oop copy_oop = copy_to_survivor_space(obj, should_mark_copy);
oopDesc::encode_store_heap_oop(p, copy_oop);
}
// When scanning the RS, we only care about objs in CS.
if (barrier == G1BarrierRS) {
_par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
}
} else {
// The object is not in collection set. If we're a root scanning
// closure during an initial mark pause (i.e. do_mark_object will
// be true) then attempt to mark the object.
if (do_mark_object) {
mark_object(p);
}
}
if (barrier == G1BarrierEvac && obj != NULL) {