On 07/31/2015 12:56 AM, Kim Barrett wrote:
On Jul 30, 2015, at 5:33 PM, David Holmes <david.hol...@oracle.com> wrote:
So I think I can either:
1. Go ahead with my change + Peter's change.
2. Give this back to core-libs while I step carefully away :-)
I *think* option (1) is at least an improvement. But I completely
missed Peter's race, despite having specifically looked for problems
there, so take my opinion with an appropriate quantity of salt.
I vote for 1 as well. I think we have now given good coverage to the two
sources of problems (the two lock-free regions):
- reference queue state can be seen while queue state is in transition
- queue empty state can be seen while reference state is in transition
New webrev, with both changes:
http://cr.openjdk.java.net/~kbarrett/8132306/webrev.01/
This looks good now. Thanks for taking both of the issues together. I
wonder if a similar racy test could be devised for the 2nd race. I doubt
the ReferenceEnqueue test was meant to catch invalid races specifically.
It was more a coincidence that it failed.
I tried to create a reproducer for 2nd race, but it is not reliable and
sometimes needs several minutes to fail.
Now I have to check if my prototype for improved Reference handling:
http://cr.openjdk.java.net/~plevart/misc/JEP132/ReferenceHandling/webrev.06/
suffers from these or similar races too. From 1st look it seems so.
Regards, Peter
