RFR (M): 8165857: CMS _overflow_list is missing volatile qualifiers
erik.osterlund at oracle.com
Mon Sep 19 11:43:34 UTC 2016
This bug is a split out of the larger JDK-8033552 for adding volatile
qualifiers to lock-free code.
The motivation is to make our implementation more robust since these
kind of issues have struck us a few times too many already.
This specific CR handles the lack of volatile qualifiers for the
_overflow_list fields of the ParallelGC ConcurrentMarkSweepGeneration
and ParNewGeneration classes.
The type of the overflow list has been changed to HeapWord *volatile per
Kim's recommendation as an oop variant requires changes to the oop class
with new overloads, which seems a bit unnecessary considering the
overflow lists are hardly proper oop lists either; it has e.g. sentinel
I went ahead and did the required changes to make the lists HeapWord
*volatile, which should make them a little bit more robust.
I will need a sponsor to push this.
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