8028710: G1 does not retire allocation buffers after reference processing work
Summary: G1 does not retire allocation buffers after reference processing work when -XX:+ParallelRefProcEnabled is enabled. This causes wrong calculation of PLAB sizes, as the amount of space wasted is not updated correctly.
Reviewed-by: brutisso
--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp Wed Apr 16 10:56:17 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp Wed Apr 16 11:05:37 2014 +0200
@@ -4562,7 +4562,7 @@
}
G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
- ParGCAllocBuffer(gclab_word_size), _retired(false) { }
+ ParGCAllocBuffer(gclab_word_size), _retired(true) { }
G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
: _g1h(g1h),
@@ -4926,8 +4926,6 @@
pss->trim_queue();
}
} while (!offer_termination());
-
- pss->retire_alloc_buffers();
}
class G1KlassScanClosure : public KlassClosure {
@@ -5753,10 +5751,8 @@
}
_gc_tracer_stw->report_gc_reference_stats(stats);
- // We have completed copying any necessary live referent objects
- // (that were not copied during the actual pause) so we can
- // retire any active alloc buffers
- pss.retire_alloc_buffers();
+
+ // We have completed copying any necessary live referent objects.
assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
double ref_proc_time = os::elapsedTime() - ref_proc_start;
--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp Wed Apr 16 10:56:17 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp Wed Apr 16 11:05:37 2014 +0200
@@ -1688,15 +1688,19 @@
public:
G1ParGCAllocBuffer(size_t gclab_word_size);
+ virtual ~G1ParGCAllocBuffer() {
+ guarantee(_retired, "Allocation buffer has not been retired");
+ }
- void set_buf(HeapWord* buf) {
+ virtual void set_buf(HeapWord* buf) {
ParGCAllocBuffer::set_buf(buf);
_retired = false;
}
- void retire(bool end_of_gc, bool retain) {
- if (_retired)
+ virtual void retire(bool end_of_gc, bool retain) {
+ if (_retired) {
return;
+ }
ParGCAllocBuffer::retire(end_of_gc, retain);
_retired = true;
}
@@ -1766,6 +1770,7 @@
G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp);
~G1ParScanThreadState() {
+ retire_alloc_buffers();
FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);
}
@@ -1876,6 +1881,7 @@
return _surviving_young_words;
}
+private:
void retire_alloc_buffers() {
for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
size_t waste = _alloc_buffers[ap]->words_remaining();
@@ -1885,8 +1891,8 @@
false /* retain */);
}
}
-private:
- #define G1_PARTIAL_ARRAY_MASK 0x2
+
+#define G1_PARTIAL_ARRAY_MASK 0x2
inline bool has_partial_array_mask(oop* ref) const {
return ((uintptr_t)ref & G1_PARTIAL_ARRAY_MASK) == G1_PARTIAL_ARRAY_MASK;
--- a/hotspot/src/share/vm/gc_implementation/shared/parGCAllocBuffer.hpp Wed Apr 16 10:56:17 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/shared/parGCAllocBuffer.hpp Wed Apr 16 11:05:37 2014 +0200
@@ -60,6 +60,7 @@
// Initializes the buffer to be empty, but with the given "word_sz".
// Must get initialized with "set_buf" for an allocation to succeed.
ParGCAllocBuffer(size_t word_sz);
+ virtual ~ParGCAllocBuffer() {}
static const size_t min_size() {
return ThreadLocalAllocBuffer::min_size();
@@ -113,7 +114,7 @@
}
// Sets the space of the buffer to be [buf, space+word_sz()).
- void set_buf(HeapWord* buf) {
+ virtual void set_buf(HeapWord* buf) {
_bottom = buf;
_top = _bottom;
_hard_end = _bottom + word_sz();
@@ -158,7 +159,7 @@
// Fills in the unallocated portion of the buffer with a garbage object.
// If "end_of_gc" is TRUE, is after the last use in the GC. IF "retain"
// is true, attempt to re-use the unused portion in the next GC.
- void retire(bool end_of_gc, bool retain);
+ virtual void retire(bool end_of_gc, bool retain);
void print() PRODUCT_RETURN;
};
@@ -238,14 +239,14 @@
void undo_allocation(HeapWord* obj, size_t word_sz);
- void set_buf(HeapWord* buf_start) {
+ virtual void set_buf(HeapWord* buf_start) {
ParGCAllocBuffer::set_buf(buf_start);
_true_end = _hard_end;
_bt.set_region(MemRegion(buf_start, word_sz()));
_bt.initialize_threshold();
}
- void retire(bool end_of_gc, bool retain);
+ virtual void retire(bool end_of_gc, bool retain);
MemRegion range() {
return MemRegion(_top, _true_end);