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src/hotspot/share/gc/shared/taskqueue.inline.hpp
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rev 55920 : 8229169: False failure of GenericTaskQueue::pop_local on architectures with weak memory model
Reviewed-by: mdoerr, kbarrett
@@ -182,10 +182,15 @@
TASKQUEUE_STATS_ONLY(stats.record_pop());
return true;
} else {
// Otherwise, the queue contained exactly one element; we take the slow
// path.
+
+ // The barrier is required to prevent reordering the two reads of _age:
+ // one is the _age.get() below, and the other is _age.top() above the if-stmt.
+ // The algorithm may fail if _age.get() reads an older value than _age.top().
+ OrderAccess::loadload();
return pop_local_slow(localBot, _age.get());
}
}
template <class E, MEMFLAGS F, unsigned int N>
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