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List:       openjdk-serviceability-dev
Subject:    Re: RFR (XS) 6976636: JVM/TI test ex03t001 fails assertion
From:       "serguei.spitsyn () oracle ! com" <serguei ! spitsyn () oracle ! com>
Date:       2014-03-17 22:17:01
Message-ID: 5327745D.7040102 () oracle ! com
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Thanks a lot, Dmitry!
Serguei

On 3/17/14 11:15 PM, dmitry.samersoff@oracle.com wrote:
> Serguei,
> The fix looks good for me.
>
> --Dmitry
>
>
>
> -----Original Message-----
> From: "serguei.spitsyn@oracle.com" <serguei.spitsyn@oracle.com>
> To: hotspot-dev@openjdk.java.net, 
> "serviceability-dev@openjdk.java.net" 
> <serviceability-dev@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 
> <http://cr.openjdk.java.net/%7Esspitsyn/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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