Review request: 8010151 : nsk/regression/b6653214 fails "assert(snapshot != NULL) failed: Worker should not be started"

[Zhengyu Gu]

The assertion appears due to snapshot variable still is not visible to 
worker thread, so make snapshot volatile.

NMT creates snapshot before starting NMT worker thread and the snapshot 
is released by worker thread during shutdown, so the assertion should 
not fail. I can not reproduce the problem with/without volatile modifier.


Bug: http://bugs.sun.com/view_bug.do?bug_id=8010151
Webrev: http://cr.openjdk.java.net/~zgu/8010151/webrev.00/ 
<http://cr.openjdk.java.net/%7Ezgu/8010151/webrev.00/>

Test:
   nsk/regression/b6653214  on Windows x64


Thanks,

-Zhengyu