archive/jdk
1
0
Fork 0
mirror of https://github.com/openjdk/jdk.git synced 2025-09-21 03:24:38 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

8159978: Use an array to store the collection set regions instead of linking through regions

Browse source 
Fix a potential problem with memory visibility in the sampling thread in the collection set by changing the way we store the collection set.

Reviewed-by: ehelin, jmasa
This commit is contained in:
Thomas Schatzl 2016-07-06 11:22:55 +02:00
parent 9a3dc1d8cc
commit 7fd90042ca
15 changed files with 404 additions and 473 deletions
Download patch file Download diff file Expand all files Collapse all files

63
hotspot/src/share/vm/gc/g1/g1YoungRemSetSamplingThread.cpp
View file

@ -71,38 +71,51 @@ void G1YoungRemSetSamplingThread::stop_service() {
_monitor.notify();
}
class G1YoungRemSetSamplingClosure : public HeapRegionClosure {
SuspendibleThreadSetJoiner* _sts;
size_t _regions_visited;
size_t _sampled_rs_lengths;
public:
G1YoungRemSetSamplingClosure(SuspendibleThreadSetJoiner* sts) :
HeapRegionClosure(), _sts(sts), _regions_visited(0), _sampled_rs_lengths(0) { }
virtual bool doHeapRegion(HeapRegion* r) {
size_t rs_length = r->rem_set()->occupied();
_sampled_rs_lengths += rs_length;
// Update the collection set policy information for this region
G1CollectedHeap::heap()->collection_set()->update_young_region_prediction(r, rs_length);
_regions_visited++;
if (_regions_visited == 10) {
if (_sts->should_yield()) {
_sts->yield();
// A gc may have occurred and our sampling data is stale and further
// traversal of the collection set is unsafe
return true;
}
_regions_visited = 0;
}
return false;
}
size_t sampled_rs_lengths() const { return _sampled_rs_lengths; }
};
void G1YoungRemSetSamplingThread::sample_young_list_rs_lengths() {
SuspendibleThreadSetJoiner sts;
G1CollectedHeap* g1h = G1CollectedHeap::heap();
G1Policy* g1p = g1h->g1_policy();
G1CollectionSet* g1cs = g1h->collection_set();
if (g1p->adaptive_young_list_length()) {
int regions_visited = 0;
HeapRegion* hr = g1cs->inc_head();
size_t sampled_rs_lengths = 0;
G1YoungRemSetSamplingClosure cl(&sts);
while (hr != NULL) {
size_t rs_length = hr->rem_set()->occupied();
sampled_rs_lengths += rs_length;
G1CollectionSet* g1cs = g1h->collection_set();
g1cs->iterate(&cl);
// Update the collection set policy information for this region
g1cs->update_young_region_prediction(hr, rs_length);
++regions_visited;
// we try to yield every time we visit 10 regions
if (regions_visited == 10) {
if (sts.should_yield()) {
sts.yield();
// A gc may have occurred and our sampling data is stale and further
// traversal of the collection set is unsafe
return;
}
regions_visited = 0;
}
assert(hr == g1cs->inc_tail() || hr->next_in_collection_set() != NULL, "next should only be null at tail of icset");
hr = hr->next_in_collection_set();
if (cl.complete()) {
g1p->revise_young_list_target_length_if_necessary(cl.sampled_rs_lengths());
}
g1p->revise_young_list_target_length_if_necessary(sampled_rs_lengths);
}
}