RFR (XS) 6976636: JVM/TI test ex03t001 fails assertion

[dmitry.samersoff at oracle.com]

Serguei,
The fix looks good for me.

--Dmitry



-----Original Message-----
From: "serguei.spitsyn at oracle.com" <serguei.spitsyn at oracle.com>
To: hotspot-dev at openjdk.java.net, "serviceability-dev at openjdk.java.net" <serviceability-dev at openjdk.java.net>
Sent: Thu, 13 Mar 2014 22:24
Subject: RFR (XS) 6976636: JVM/TI test ex03t001 fails assertion

Please, review the fix for:
   https://bugs.openjdk.java.net/browse/JDK-6976636


Open webrev:
http://cr.openjdk.java.net/~sspitsyn/webrevs/2014/hotspot/6976636-JVMTI-unload.1

Summary:

   This is a Nightly Stabilization issue.
   The class unload event post in the JvmtiExport.cpp fails at the assert
   assuming the proxy thread causing the class unload must be a JavaThread.
   It is not the case when the proxy thread is a CMS ConcurrentGCThread.

   This fix is to relax this check allowing this case.
   The downside of this approach is that the jthread parameter passed to the
   even handler callback is NULL for the CMS thread.
   This must be Ok as it would indicates that the proxy thread is a CMS 
thread.

   In fact, I have a doubt this parameter is needed at all.
   So that an alternative approach could be to remove it from the event 
callback.
   My preference is to leave the jthread parameter as it is as it does 
not impact anything.
   The class unload event is implemented as a source debug extension for the
   sake of testing the extension functionality. The JDWP agent does not 
use it.
   The class unload events are not expected to be used by any external tool.

   As a consequence of this fix the failing nsk.jvmti test ex03t001 must 
be tweeked as well.
   If review is positive then I'll file a bug and proceed with the test fix.

Testing:
   Running the failing test: nsk/jvmti/scenarios/extension/EX03/ex03t001


Thanks,
Serguei
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