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

[Yasumasa Suenaga]

Hi David,

> 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" ...

The change for jvmtiExport.cpp can apply jdk8u:

   http://hg.openjdk.java.net/jdk8u/jdk8u-dev/hotspot/file/d55ea2916525/src/share/vm/prims/jvmtiExport.cpp#l2270

I think HotSpot in jdk8u ignores exception and return JNI_OK even if Agent_OnAttach() fails.
OTOH, the change for diagnosticCommand.cpp affects jdk9 only.


Thanks,

Yasumasa


On 2016/09/06 9:54, David Holmes wrote:
> 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
>>