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Hello there, I'm currently having an issue with my MPI runtime. At installation my MPI installation behaved normally and as expected, ie : $mpirun -np 4 my_program was indeed launching ...
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  1. #1
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    MPIRUN fails to launch multiple processus


    Hello there,

    I'm currently having an issue with my MPI runtime. At installation my MPI installation behaved normally and as expected, ie :
    $mpirun -np 4 my_program
    was indeed launching 4 instances/nodes of "my_program", on a single core, multicore or multi-system cloud.
    Now it's only capable of launching a single instance no matter what argument I give to the -np option. I haven't changed any parameters in my installation (Ubuntu 10.04)... at least not consciously. Anybody has an idea what might be behind this issue ?

    My teacher and fellow students are all puzzled and can't get a grip on it too.

  2. #2
    Linux Guru Rubberman's Avatar
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    You have to ask yourself "what changed" on the system between the time it worked, and the time it didn't. Other than that, you don't provide enough information to help.
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

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    The only thing that has changed in between is the installation of the mpich2 packet. I've checked the alternatives linking and I have manually set it to link mpirun command with the mpich package (and not the mpich2).

    For the rest nothing has changed. I checked the problem while using a MPI-program which I previously used and that worked without a flaw on multiple nodes (-np 4 / 10 / 100, etc) . So I'm sure it's not my programming that is bugged.

  4. #4
    Linux Guru Rubberman's Avatar
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    So, have you tried removing/reverting the updates?
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

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    Yes. I actually tried the uninstall of mpich2 from the start and it did not change anything. I should have mentioned it in my previous message, sorry for not doing so.

    Still, I tried again after your reply, this time also uninstalling mpich-bin before reinstalling it. Now the issue disappeared. Eventhough I'm not quite sure about the how and why, I suspect the mpich2 lib's to mess with the mpich-bin implementation.

    Thank you very much for your help and ideas
    Helcaraxan

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