Thu, 22 Sep 2011 10:57:37 -0700
6484982: G1: process references during evacuation pauses
Summary: 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
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25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1OOPCLOSURES_INLINE_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1OOPCLOSURES_INLINE_HPP
28 #include "gc_implementation/g1/concurrentMark.inline.hpp"
29 #include "gc_implementation/g1/g1CollectedHeap.hpp"
30 #include "gc_implementation/g1/g1OopClosures.hpp"
31 #include "gc_implementation/g1/g1RemSet.hpp"
33 /*
34 * This really ought to be an inline function, but apparently the C++
35 * compiler sometimes sees fit to ignore inline declarations. Sigh.
36 */
38 // This must a ifdef'ed because the counting it controls is in a
39 // perf-critical inner loop.
40 #define FILTERINTOCSCLOSURE_DOHISTOGRAMCOUNT 0
42 template <class T> inline void FilterIntoCSClosure::do_oop_nv(T* p) {
43 T heap_oop = oopDesc::load_heap_oop(p);
44 if (!oopDesc::is_null(heap_oop) &&
45 _g1->obj_in_cs(oopDesc::decode_heap_oop_not_null(heap_oop))) {
46 _oc->do_oop(p);
47 #if FILTERINTOCSCLOSURE_DOHISTOGRAMCOUNT
48 if (_dcto_cl != NULL)
49 _dcto_cl->incr_count();
50 #endif
51 }
52 }
54 #define FILTEROUTOFREGIONCLOSURE_DOHISTOGRAMCOUNT 0
56 template <class T> inline void FilterOutOfRegionClosure::do_oop_nv(T* p) {
57 T heap_oop = oopDesc::load_heap_oop(p);
58 if (!oopDesc::is_null(heap_oop)) {
59 HeapWord* obj_hw = (HeapWord*)oopDesc::decode_heap_oop_not_null(heap_oop);
60 if (obj_hw < _r_bottom || obj_hw >= _r_end) {
61 _oc->do_oop(p);
62 #if FILTEROUTOFREGIONCLOSURE_DOHISTOGRAMCOUNT
63 _out_of_region++;
64 #endif
65 }
66 }
67 }
69 // This closure is applied to the fields of the objects that have just been copied.
70 template <class T> inline void G1ParScanClosure::do_oop_nv(T* p) {
71 T heap_oop = oopDesc::load_heap_oop(p);
73 if (!oopDesc::is_null(heap_oop)) {
74 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
75 if (_g1->in_cset_fast_test(obj)) {
76 // We're not going to even bother checking whether the object is
77 // already forwarded or not, as this usually causes an immediate
78 // stall. We'll try to prefetch the object (for write, given that
79 // we might need to install the forwarding reference) and we'll
80 // get back to it when pop it from the queue
81 Prefetch::write(obj->mark_addr(), 0);
82 Prefetch::read(obj->mark_addr(), (HeapWordSize*2));
84 // slightly paranoid test; I'm trying to catch potential
85 // problems before we go into push_on_queue to know where the
86 // problem is coming from
87 assert(obj == oopDesc::load_decode_heap_oop(p),
88 "p should still be pointing to obj");
89 _par_scan_state->push_on_queue(p);
90 } else {
91 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
92 }
93 }
94 }
96 template <class T> inline void G1ParPushHeapRSClosure::do_oop_nv(T* p) {
97 T heap_oop = oopDesc::load_heap_oop(p);
99 if (!oopDesc::is_null(heap_oop)) {
100 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
101 if (_g1->in_cset_fast_test(obj)) {
102 Prefetch::write(obj->mark_addr(), 0);
103 Prefetch::read(obj->mark_addr(), (HeapWordSize*2));
105 // Place on the references queue
106 _par_scan_state->push_on_queue(p);
107 }
108 }
109 }
111 template <class T> inline void G1CMOopClosure::do_oop_nv(T* p) {
112 assert(_g1h->is_in_g1_reserved((HeapWord*) p), "invariant");
113 assert(!_g1h->is_on_master_free_list(
114 _g1h->heap_region_containing((HeapWord*) p)), "invariant");
116 oop obj = oopDesc::load_decode_heap_oop(p);
117 if (_cm->verbose_high()) {
118 gclog_or_tty->print_cr("[%d] we're looking at location "
119 "*"PTR_FORMAT" = "PTR_FORMAT,
120 _task->task_id(), p, (void*) obj);
121 }
122 _task->deal_with_reference(obj);
123 }
125 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1OOPCLOSURES_INLINE_HPP