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6484982: G1: process references during evacuation pauses

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G1 now uses two reference processors - one is used by concurrent marking and the other is used by STW GCs (both full and incremental evacuation pauses). In an evacuation pause, the reference processor is embedded into the closures used to scan objects. Doing so causes causes reference objects to be 'discovered' by the reference processor. At the end of the evacuation pause, these discovered reference objects are processed - preserving (and copying) referent objects (and their reachable graphs) as appropriate.

Reviewed-by: ysr, jwilhelm, brutisso, stefank, tonyp
This commit is contained in:
John Cuthbertson 2011-09-22 10:57:37 -07:00
parent 70bb8e788e
commit 1b62d10b4b
20 changed files with 1448 additions and 632 deletions
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40
hotspot/src/share/vm/gc_implementation/g1/heapRegion.cpp
View file

@ -45,7 +45,7 @@ HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
FilterKind fk) :
ContiguousSpaceDCTOC(hr, cl, precision, NULL),
_hr(hr), _fk(fk), _g1(g1)
{}
{ }
FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
OopClosure* oc) :
@ -214,8 +214,37 @@ void HeapRegionDCTOC::walk_mem_region_with_cl(MemRegion mr,
int oop_size;
OopClosure* cl2 = cl;
FilterIntoCSClosure intoCSFilt(this, g1h, cl);
// If we are scanning the remembered sets looking for refs
// into the collection set during an evacuation pause then
// we will want to 'discover' reference objects that point
// to referents in the collection set.
//
// Unfortunately it is an instance of FilterIntoCSClosure
// that is iterated over the reference fields of oops in
// mr (and not the G1ParPushHeapRSClosure - which is the
// cl parameter).
// If we set the _ref_processor field in the FilterIntoCSClosure
// instance, all the reference objects that are walked
// (regardless of whether their referent object's are in
// the cset) will be 'discovered'.
//
// The G1STWIsAlive closure considers a referent object that
// is outside the cset as alive. The G1CopyingKeepAliveClosure
// skips referents that are not in the cset.
//
// Therefore reference objects in mr with a referent that is
// outside the cset should be OK.
ReferenceProcessor* rp = _cl->_ref_processor;
if (rp != NULL) {
assert(rp == _g1->ref_processor_stw(), "should be stw");
assert(_fk == IntoCSFilterKind, "should be looking for refs into CS");
}
FilterIntoCSClosure intoCSFilt(this, g1h, cl, rp);
FilterOutOfRegionClosure outOfRegionFilt(_hr, cl);
switch (_fk) {
case IntoCSFilterKind: cl2 = &intoCSFilt; break;
case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;
@ -239,16 +268,19 @@ void HeapRegionDCTOC::walk_mem_region_with_cl(MemRegion mr,
case NoFilterKind:
bottom = walk_mem_region_loop(cl, g1h, _hr, bottom, top);
break;
case IntoCSFilterKind: {
FilterIntoCSClosure filt(this, g1h, cl);
FilterIntoCSClosure filt(this, g1h, cl, rp);
bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
break;
}
case OutOfRegionFilterKind: {
FilterOutOfRegionClosure filt(_hr, cl);
bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
break;
}
default:
ShouldNotReachHere();
}
@ -483,7 +515,7 @@ HeapRegion::
HeapRegion(size_t hrs_index, G1BlockOffsetSharedArray* sharedOffsetArray,
MemRegion mr, bool is_zeroed)
: G1OffsetTableContigSpace(sharedOffsetArray, mr, is_zeroed),
_next_fk(HeapRegionDCTOC::NoFilterKind), _hrs_index(hrs_index),
_hrs_index(hrs_index),
_humongous_type(NotHumongous), _humongous_start_region(NULL),
_in_collection_set(false),
_next_in_special_set(NULL), _orig_end(NULL),