RFR [8034262] Test java/lang/ProcessBuilder/CloseRace.java fails

[Ivan Gerasimov]

Hello everybody!

The test java/lang/ProcessBuilder/CloseRace.java was reported to 
intermittently fail.
The test timed out, which should mean that at least one of the child 
threads was never interrupted.

I couldn't reproduce the failure, but I suspect it might happen due to 
call to interrupt() before the child thread became alive (I'm not really 
sure if it's possible to be non-alive after call to start()).
The fix is to explicitly synchronize children with the parent.

Would you please help review the fix?

BUGURL: https://bugs.openjdk.java.net/browse/JDK-8034262
WEBREV: http://cr.openjdk.java.net/~igerasim/8034262/0/webrev/

Sincerely yours,
Ivan