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src/share/vm/gc_implementation/g1/heapRegionManager.cpp
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rev 7182 : imported patch 8058298
rev 7183 : imported patch rev1
rev 7185 : [mq]: rev3
@@ -258,37 +258,34 @@
err_msg("The region at the current position %u must be available or at the end of the heap.", cur));
#endif
return num_regions;
}
-uint HeapRegionManager::start_region_for_worker(uint worker_i, uint num_workers, uint num_regions) const {
- return num_regions * worker_i / num_workers;
-}
-
-void HeapRegionManager::par_iterate(HeapRegionClosure* blk, uint worker_id, uint num_workers, jint claim_value) const {
- const uint start_index = start_region_for_worker(worker_id, num_workers, _allocated_heapregions_length);
+void HeapRegionManager::par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer) const {
+ const uint start_index = hrclaimer->start_region_for_worker(worker_id);
// Every worker will actually look at all regions, skipping over regions that
// are currently not committed.
// This also (potentially) iterates over regions newly allocated during GC. This
// is no problem except for some extra work.
- for (uint count = 0; count < _allocated_heapregions_length; count++) {
- const uint index = (start_index + count) % _allocated_heapregions_length;
- assert(0 <= index && index < _allocated_heapregions_length, "sanity");
+ const uint n_regions = hrclaimer->n_regions();
+ for (uint count = 0; count < n_regions; count++) {
+ const uint index = (start_index + count) % n_regions;
+ assert(0 <= index && index < n_regions, "sanity");
// Skip over unavailable regions
if (!is_available(index)) {
continue;
}
HeapRegion* r = _regions.get_by_index(index);
// We'll ignore "continues humongous" regions (we'll process them
// when we come across their corresponding "start humongous"
// region) and regions already claimed.
- if (r->claim_value() == claim_value || r->is_continues_humongous()) {
+ if (hrclaimer->is_region_claimed(index) || r->is_continues_humongous()) {
continue;
}
// OK, try to claim it
- if (!r->claimHeapRegion(claim_value)) {
+ if (!hrclaimer->claim_region(index)) {
continue;
}
// Success!
if (r->is_starts_humongous()) {
// If the region is "starts humongous" we'll iterate over its
@@ -304,17 +301,15 @@
assert(chr->is_continues_humongous(), "Must be humongous region");
assert(chr->humongous_start_region() == r,
err_msg("Must work on humongous continuation of the original start region "
PTR_FORMAT ", but is " PTR_FORMAT, p2i(r), p2i(chr)));
- assert(chr->claim_value() != claim_value,
+ assert(!hrclaimer->is_region_claimed(ch_index),
"Must not have been claimed yet because claiming of humongous continuation first claims the start region");
- bool claim_result = chr->claimHeapRegion(claim_value);
- // We should always be able to claim it; no one else should
- // be trying to claim this region.
- guarantee(claim_result, "We should always be able to claim the is_continues_humongous part of the humongous object");
+ // There's no need to actually claim the continues humongous region, but we can do it in an assert as an extra precaution.
+ assert(hrclaimer->claim_region(ch_index), "We should always be able to claim the continuesHumongous part of the humongous object");
bool res2 = blk->doHeapRegion(chr);
if (res2) {
return;
}
@@ -443,5 +438,33 @@
void HeapRegionManager::verify_optional() {
verify();
}
#endif // PRODUCT
+HeapRegionClaimer::HeapRegionClaimer(uint n_workers) :
+ _n_workers(n_workers), _n_regions(G1CollectedHeap::heap()->_hrm._allocated_heapregions_length), _claims(NULL) {
+ assert(n_workers > 0, "Need at least one worker.");
+ _claims = NEW_C_HEAP_ARRAY(uint, _n_regions, mtGC);
+ memset(_claims, Unclaimed, sizeof(*_claims) * _n_regions);
+}
+
+HeapRegionClaimer::~HeapRegionClaimer() {
+ if (_claims != NULL) {
+ FREE_C_HEAP_ARRAY(uint, _claims, mtGC);
+ }
+}
+
+uint HeapRegionClaimer::start_region_for_worker(uint worker_id) const {
+ assert(worker_id < _n_workers, "Invalid worker_id.");
+ return _n_regions * worker_id / _n_workers;
+}
+
+bool HeapRegionClaimer::is_region_claimed(uint region_index) const {
+ assert(region_index < _n_regions, "Invalid index.");
+ return _claims[region_index] == Claimed;
+}
+
+bool HeapRegionClaimer::claim_region(uint region_index) {
+ assert(region_index < _n_regions, "Invalid index.");
+ uint old_val = Atomic::cmpxchg(Claimed, &_claims[region_index], Unclaimed);
+ return old_val == Unclaimed;
+}
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