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src/hotspot/share/gc/shared/referenceProcessor.cpp
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rev 49831 : imported patch 8201492-properly-implement-non-contiguous-reference-processing
rev 49834 : [mq]: 8202021-cleanup-referenceprocessor
rev 49835 : [mq]: 8202021-stefanj-review
rev 49836 : [mq]: 8202017-reference-processor-remove-enqueue
@@ -273,117 +273,10 @@
phase_times->set_total_time_ms((os::elapsedTime() - start_time) * 1000);
return stats;
}
-void ReferenceProcessor::enqueue_discovered_references(AbstractRefProcTaskExecutor* task_executor,
- ReferenceProcessorPhaseTimes* phase_times) {
- // Enqueue references that are not made active again, and
- // clear the decks for the next collection (cycle).
- enqueue_discovered_reflists(task_executor, phase_times);
-
- // Stop treating discovered references specially.
- disable_discovery();
-}
-
-void ReferenceProcessor::enqueue_discovered_reflist(DiscoveredList& refs_list) {
- // Given a list of refs linked through the "discovered" field
- // (java.lang.ref.Reference.discovered), self-loop their "next" field
- // thus distinguishing them from active References, then
- // prepend them to the pending list.
- //
- // The Java threads will see the Reference objects linked together through
- // the discovered field. Instead of trying to do the write barrier updates
- // in all places in the reference processor where we manipulate the discovered
- // field we make sure to do the barrier here where we anyway iterate through
- // all linked Reference objects. Note that it is important to not dirty any
- // cards during reference processing since this will cause card table
- // verification to fail for G1.
- log_develop_trace(gc, ref)("ReferenceProcessor::enqueue_discovered_reflist list " INTPTR_FORMAT, p2i(&refs_list));
-
- oop obj = NULL;
- oop next_discovered = refs_list.head();
- // Walk down the list, self-looping the next field
- // so that the References are not considered active.
- while (obj != next_discovered) {
- obj = next_discovered;
- assert(obj->is_instance(), "should be an instance object");
- assert(InstanceKlass::cast(obj->klass())->is_reference_instance_klass(), "should be reference object");
- next_discovered = java_lang_ref_Reference::discovered(obj);
- log_develop_trace(gc, ref)(" obj " INTPTR_FORMAT "/next_discovered " INTPTR_FORMAT, p2i(obj), p2i(next_discovered));
- assert(java_lang_ref_Reference::next(obj) == NULL,
- "Reference not active; should not be discovered");
- // Self-loop next, so as to make Ref not active.
- java_lang_ref_Reference::set_next_raw(obj, obj);
- if (next_discovered != obj) {
- HeapAccess<AS_NO_KEEPALIVE>::oop_store_at(obj, java_lang_ref_Reference::discovered_offset, next_discovered);
- } else {
- // This is the last object.
- // Swap refs_list into pending list and set obj's
- // discovered to what we read from the pending list.
- oop old = Universe::swap_reference_pending_list(refs_list.head());
- HeapAccess<AS_NO_KEEPALIVE>::oop_store_at(obj, java_lang_ref_Reference::discovered_offset, old);
- }
- }
-}
-
-// Parallel enqueue task
-class RefProcEnqueueTask: public AbstractRefProcTaskExecutor::EnqueueTask {
-public:
- RefProcEnqueueTask(ReferenceProcessor& ref_processor,
- DiscoveredList discovered_refs[],
- int n_queues,
- ReferenceProcessorPhaseTimes* phase_times)
- : EnqueueTask(ref_processor, discovered_refs, n_queues, phase_times)
- { }
-
- virtual void work(unsigned int work_id) {
- RefProcWorkerTimeTracker tt(ReferenceProcessorPhaseTimes::RefEnqueue, _phase_times, work_id);
-
- assert(work_id < (unsigned int)_ref_processor.max_num_queues(), "Index out-of-bounds");
- // Simplest first cut: static partitioning.
- int index = work_id;
- // The increment on "index" must correspond to the maximum number of queues
- // (n_queues) with which that ReferenceProcessor was created. That
- // is because of the "clever" way the discovered references lists were
- // allocated and are indexed into.
- assert(_n_queues == (int) _ref_processor.max_num_queues(), "Different number not expected");
- for (int j = 0;
- j < ReferenceProcessor::number_of_subclasses_of_ref();
- j++, index += _n_queues) {
- _ref_processor.enqueue_discovered_reflist(_refs_lists[index]);
- _refs_lists[index].set_head(NULL);
- _refs_lists[index].set_length(0);
- }
- }
-};
-
-// Enqueue references that are not made active again
-void ReferenceProcessor::enqueue_discovered_reflists(AbstractRefProcTaskExecutor* task_executor,
- ReferenceProcessorPhaseTimes* phase_times) {
-
- ReferenceProcessorStats stats(total_count(_discoveredSoftRefs),
- total_count(_discoveredWeakRefs),
- total_count(_discoveredFinalRefs),
- total_count(_discoveredPhantomRefs));
-
- RefProcEnqueueTimeTracker tt(phase_times, stats);
-
- if (_processing_is_mt && task_executor != NULL) {
- // Parallel code
- RefProcEnqueueTask tsk(*this, _discovered_refs, _max_num_queues, phase_times);
- task_executor->execute(tsk);
- } else {
- // Serial code: call the parent class's implementation
- for (uint i = 0; i < _max_num_queues * number_of_subclasses_of_ref(); i++) {
- enqueue_discovered_reflist(_discovered_refs[i]);
- _discovered_refs[i].set_head(NULL);
- _discovered_refs[i].set_length(0);
- }
- }
-}
-
void DiscoveredListIterator::load_ptrs(DEBUG_ONLY(bool allow_null_referent)) {
_discovered_addr = java_lang_ref_Reference::discovered_addr_raw(_current_discovered);
oop discovered = java_lang_ref_Reference::discovered(_current_discovered);
assert(_discovered_addr && oopDesc::is_oop_or_null(discovered),
"Expected an oop or NULL for discovered field at " PTR_FORMAT, p2i(discovered));
@@ -425,10 +318,29 @@
void DiscoveredListIterator::clear_referent() {
RawAccess<>::oop_store(_referent_addr, oop(NULL));
}
+void DiscoveredListIterator::enqueue() {
+ // Self-loop next, so as to make Ref not active.
+ java_lang_ref_Reference::set_next_raw(_current_discovered, _current_discovered);
+
+ HeapAccess<AS_NO_KEEPALIVE>::oop_store_at(_current_discovered,
+ java_lang_ref_Reference::discovered_offset,
+ _next_discovered);
+}
+
+void DiscoveredListIterator::complete_enqeue() {
+ if (_prev_discovered != NULL) {
+ // This is the last object.
+ // Swap refs_list into pending list and set obj's
+ // discovered to what we read from the pending list.
+ oop old = Universe::swap_reference_pending_list(_refs_list.head());
+ HeapAccess<AS_NO_KEEPALIVE>::oop_store_at(_prev_discovered, java_lang_ref_Reference::discovered_offset, old);
+ }
+}
+
// NOTE: process_phase*() are largely similar, and at a high level
// merely iterate over the extant list applying a predicate to
// each of its elements and possibly removing that element from the
// list and applying some further closures to that element.
// We should consider the possibility of replacing these
@@ -572,15 +484,17 @@
iter.clear_referent();
} else {
// keep the referent around
iter.make_referent_alive();
}
+ iter.enqueue();
log_develop_trace(gc, ref)("Adding %sreference (" INTPTR_FORMAT ": %s) as pending",
clear_referent ? "cleared " : "", p2i(iter.obj()), iter.obj()->klass()->internal_name());
assert(oopDesc::is_oop(iter.obj(), UseConcMarkSweepGC), "Adding a bad reference");
iter.next();
}
+ iter.complete_enqeue();
// Close the reachable set
complete_gc->do_void();
}
void
@@ -688,10 +602,12 @@
{
RefProcWorkerTimeTracker tt(ReferenceProcessorPhaseTimes::RefPhase3, _phase_times, i);
_ref_processor.process_phase3(_refs_lists[i], _clear_referent,
&is_alive, &keep_alive, &complete_gc);
+ _refs_lists[i].set_head(NULL);
+ _refs_lists[i].set_length(0);
}
private:
bool _clear_referent;
};
@@ -801,17 +717,10 @@
log_reflist_counts(ref_lists, _num_queues, balanced_total_refs);
assert(total_refs == balanced_total_refs, "Balancing was incomplete");
#endif
}
-void ReferenceProcessor::balance_all_queues() {
- balance_queues(_discoveredSoftRefs);
- balance_queues(_discoveredWeakRefs);
- balance_queues(_discoveredFinalRefs);
- balance_queues(_discoveredPhantomRefs);
-}
-
void ReferenceProcessor::process_discovered_reflist(
DiscoveredList refs_lists[],
ReferencePolicy* policy,
bool clear_referent,
BoolObjectClosure* is_alive,
@@ -876,10 +785,12 @@
task_executor->execute(phase3);
} else {
for (uint i = 0; i < _max_num_queues; i++) {
process_phase3(refs_lists[i], clear_referent,
is_alive, keep_alive, complete_gc);
+ refs_lists[i].set_head(NULL);
+ refs_lists[i].set_length(0);
}
}
}
}
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