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Re: PMDA related question

To: Madhu Sudhan R Tera <mst9696@xxxxxxxxxxx>
Subject: Re: PMDA related question
From: Ken McDonell <kenmcd@xxxxxxxxxxxxxxxxx>
Date: Tue, 15 Oct 2002 09:37:15 +1000
Cc: pcp@xxxxxxxxxxx
In-reply-to: <Pine.GSO.4.44.0210100601001.22344-100000@xxxxxxxxxxxxxxxxx>
Sender: pcp-bounce@xxxxxxxxxxx
On Thu, 10 Oct 2002, Madhu Sudhan R Tera wrote:

> Hello!
> We developed a PMDA, for obtaining the network charecteristics of the
> processes in the system, based on the examples given in the sample
> pmdas.While installing the pmda we select the options for running it as
> both collector and monitor and options -socket, internet and specify the port.
> The pmda runs well for few times when requested for metrics. But after
> some time it crashes. This is happening very frequently. We are unable to
> find the source of this problem.

OK ...

1. is the pmda dumping core?  look in /var/log/pcp/pmcd for a core file,
   and see if it is your pmda.

   If it is, then
   (a) build the pmda compiled -g and attach gdb to the pmda process
       once pmcd starts it and wait for it to fail,
   (b) else try debugging the pmda with dbpmda (a tool designed for _just_
       this purpose)

2. if not, look in /var/log/pcp/pmcd ... yourpmda.log and pmcd.log should
   have interesting stuff in them, probably talking about timeouts I would
   guess

   To work around this you can try
        $ pmstore pmcd.control.timeout 60
   but to fix it will need you to understand why your pmda is taking so long
   to respond, and making it faster or providing a multi-threaded pmda,
   e.g. like the weblog pmda

3. consider adding -D pdu to the command line arguments in /etc/pmcd.conf
   for your pmda, and the inspecting yourpmda.log after the failure ... this
   will dump all the messages passing between pmcd and your pmda

4. turn on the pmcd event tracing ring buffer, so you can see the end of the
   message exchanges before a pmda failure (the messages will be in pmcd.log)
   ... once pmcd is running with your pmda ...

        $ pmstore pmcd.control.debug 2048
        $ pmstore pmcd.control.traceconn 1
        $ pmstore pmcd.control.tracepdu 1

> Any leads are greatly appreciated.

If all else fails, send me pmcd.log and yourpmda.log with 3. and 4. enabled.

> Thank you,
> With regards,
> MadhuSudhan Reddy Tera
>
>  --------------------------------------------------
> |Department of Computing and Information Sciences, |
> |Kansas State University,                          |
> |Manhattan, KS 66502.                              |
> |ph no:785-537-3276                                |
>  --------------------------------------------------
>


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