RFR 7132378: Race in FutureTask if used with explicit set ( not Runnable )

[Chris Hegarty]

This issue was raised on the jdk7u-dev mailing list [1].

The change is to update the FutureTask implementation to what is in 
Doug's CVS. The old implementation using AbstractQueuedSynchronizer is 
replaced with a control "state" field that is updated by CAS to track 
completion, along with a Treiber stack to hold waiting threads.

http://cr.openjdk.java.net/~chegar/7132378/webrev.00/webrev/

I have already reviewed this change. The diffs in the webrev are not all 
that useful, I reviewed it by going through the new file.

Doug,
   I added a new test for this. It fails about 1 in every 3-4 runs on 
some of the boxes I have access to. Is this useful? Would you want to 
take it into your CVS?

-Chris.

[1] 
http://mail.openjdk.java.net/pipermail/jdk7u-dev/2012-January/001439.html