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

Tue, 06 Sep 2016 11:49:21 -0700 

Hi Yasumasa,

Please, find my comment below.


On 9/6/16 06:06, Yasumasa Suenaga wrote:

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. 


This needs to be answered as well.


Thanks,
Serguei
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" <yasue...@gmail.com
<mailto:yasue...@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

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