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Subject: Re: [OMPI devel] XML request
From: Neil Ludban (nludban_at_[hidden])
Date: 2009-09-01 13:43:13


> Date: Mon, 31 Aug 2009 20:26:20 -0500
> From: Greg Watson <g.watson_at_[hidden]>
> Subject: Re: [OMPI devel] XML request
> To: Open MPI Developers <devel_at_[hidden]>
> Message-ID: <7C3BD80B-2E0D-4188-BA0A-9B4963AE2964_at_[hidden]>
> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
>
> Hey Ralph,
>
> Unfortunately I don't think this is going to work for us. Most of the
> time we're starting the mpirun command using the ssh exec or shell
> service, neither of which provide any mechanism for reading from file
> descriptors other than 1 or 2. The only alternatives I see are:
>
> 1. Provide a separate command that starts mpirun at the end of a pipe
> that is connected to the fd passed using the -xml-fd argument. This
> command would need to be part of the OMPI distribution, because the
> whole purpose of the XML was to provide an out-of-the-box experience
> when using PTP with OMPI.
>
> 2. Implement an -xml-file option, but I could write the code for you.
>
> 3. Go back to limiting XML output to the map only.
>
> None of these are particularly ideal. If you can think of anything
> else, let me know.

I don't think there's a nicer way to do this:

if (xml_output) {
   FILE *fxml = fopen("/dev/stdout", "w");
   freopen("/dev/stderr", "w", stdout);
}

You could also replace file descriptors 1 and 2 with pipes and
read data back in, convert to XML, and send it on to the dup'd
fd 1. But this would cause problems if there were any debug
printfs that were timing sensitive.