RFR(S): JDK-8054194 jstack crash: assert(handle != NULL) failed: JNI handle should not be null

[Dmitry Samersoff]

Hi Everyone,

Please review small agent changes:

http://cr.openjdk.java.net/~dsamersoff/JDK-8054194/webrev.01/

Under windows, If jstack attempts to attach to java process that is
being killed by someone else, GetStaticObjectField might return NULL.

-Dmitry

-- 
Dmitry Samersoff
Oracle Java development team, Saint Petersburg, Russia
* I would love to change the world, but they won't give me the sources.