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Subject: Re: [OMPI users] Handling output of processes
From: Ralph Castain (rhc_at_[hidden])
Date: 2009-01-25 07:20:47

For those of you following this thread:

I have been impressed by the various methods used to grab the output
from processes. Since this is clearly something of interest to a broad
audience, I would like to try and make this easier to do by adding
some options to mpirun. Coming in 1.3.1 will be --tag-output, which
will automatically tag each line of output with the rank of the
process - this was already in the works, but obviously doesn't meet
the needs expressed here.

I have done some prelim work on a couple of options based on this

1. spawn a screen and redirect process output to it, with the ability
to request separate screens for each specified rank. Obviously,
specifying all ranks would be the equivalent of replacing "my_app" on
the mpirun cmd line with "xterm my_app". However, there are cases
where you only need to see the output from a subset of the ranks, and
that is the intent of this option.

2. redirect output of specified processes to files using the provided
filename appended with ".rank". You can do this for all ranks, or a
specified subset of them.

3. timestamp output

Is there anything else people would like to see?

It is also possible to write a dedicated app such as Jody described,
but that is outside my purview for now due to priorities. However, I
can provide technical advice to such an effort, so feel free to ask.


On Jan 23, 2009, at 12:19 PM, Gijsbert Wiesenekker wrote:

> jody wrote:
>> Hi
>> I have a small cluster consisting of 9 computers (8x2 CPUs, 1x4
>> CPUs).
>> I would like to be able to observe the output of the processes
>> separately during an mpirun.
>> What i currently do is to apply the mpirun to a shell script which
>> opens a xterm for each process,
>> which then starts the actual application.
>> This works, but is a bit complicated, e.g. finding the window you're
>> interested in among 19 others.
>> So i was wondering is there a possibility to capture the processes'
>> outputs separately, so
>> i can make an application in which i can switch between the different
>> processor outputs?
>> I could imagine that could be done by wrapper applications which
>> redirect the output over a TCP
>> socket to a server application.
>> But perhaps there is an easier way, or something like this alread
>> does exist?
>> Thank You
>> Jody
>> _______________________________________________
>> users mailing list
>> users_at_[hidden]
> For C I use a printf wrapper function that writes the output to a
> logfile. I derive the name of the logfile from the mpi_id. It
> prefixes the lines with a time-stamp, so you also get some basic
> profile information. I can send you the source code if you like.
> Regards,
> Gijsbert
> _______________________________________________
> users mailing list
> users_at_[hidden]