RFR: JDK-8164913: JVMTI.agent_load dcmd should show useful error message

[David Holmes]

Hi Yasumasa,

On 1/09/2016 1:47 PM, Yasumasa Suenaga wrote:
> Hi all,
>
> I think RDP1 has been started.
> Cannot I fix this?

"P4-P5 bugs should, in general, be left to future releases unless they
only affect documentation, demos, or tests, in which case they should be
identified as such with the "noreg-doc", "noreg-demo", and "noreg-self"
labels, respectively." [1]

This is due to the need to stabilize changes as we head towards GA.

I think you would have to justify why this should be a P3 rather than P4 
issue. Is this something specific to code added in 9? If so that is 
motivation as we should not have a new feature with known bugs if we can 
avoid it. But if this already exists in JDK 8 and is a long standing 
"bug" ...

David

[1] http://mail.openjdk.java.net/pipermail/jdk9-dev/2016-August/004777.html


> This problem is that jcmd shows incorrect status when JVMTI agent cannot
> be attached.
> I think this problem should be fixed in 9 GA.
> The users who want.to attach JVMTI agent want to know
> whether it succeed.
>
> Yasumasa
>
>
> 2016/08/29 15:42 "Yasumasa Suenaga" <yasuenag at gmail.com
> <mailto:yasuenag at gmail.com>>:
>
>         This comment no longer matches the code and should be deleted:
>
>         2412       // Agent_OnAttach executed so completion status is JNI_OK
>         2413       st->print_cr("return code: %d", result);
>
>
>     Thanks David!
>     I removed it in new webrev.
>
>       http://cr.openjdk.java.net/~ysuenaga/JDK-8164913/webrev.01/
>     <http://cr.openjdk.java.net/~ysuenaga/JDK-8164913/webrev.01/>
>
>
>     Yasumasa
>
>
>     On 2016/08/29 12:59, David Holmes wrote:
>
>         Hi Yasumasa,
>
>         On 28/08/2016 10:47 PM, Yasumasa Suenaga wrote:
>
>             Hi all,
>
>             If we try to attach invalid JVMTI agent via JVMTI.agent_load
>             dcmd, we
>             will get
>             "Command executed successfully". However, it implies error in
>             JVMTIAgentLoadDCmd.
>
>             This message is from JCmd.java when jcmd does not receive
>             output from
>             target VM.
>             So we should send error message from JVMTIAgentLoadDCmd.
>
>             I uploaded a webrev for it. Could you review it?
>
>
>             http://cr.openjdk.java.net/~ysuenaga/JDK-8164913/webrev.00/
>             <http://cr.openjdk.java.net/~ysuenaga/JDK-8164913/webrev.00/>
>
>
>         This seems reasonable.
>
>         src/share/vm/prims/jvmtiExport.cpp
>
>         This comment no longer matches the code and should be deleted:
>
>         2412       // Agent_OnAttach executed so completion status is JNI_OK
>         2413       st->print_cr("return code: %d", result);
>
>         Thanks,
>         David
>
>             I cannot access JPRT.
>             So I need a sponsor.
>
>
>             Thanks,
>
>             Yasumasa
>