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<TITLE>RE: [mpich-discuss] disable-auto-cleanup send/receive example</TITLE>
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<P><FONT SIZE=2>On 11/02/2011 07:24 PM, Pavan Balaji wrote:<BR>
<BR>
Hi Darius, Pavan,<BR>
<BR>
> In your program, if I added a<BR>
> sleep(1);<BR>
> MPI_Iprobe(0, 0, MPI_COMM_WORLD, &flag, MPI_STATUS_IGNORE);<BR>
> in the error case of the receive, it did run as you expected. <BR>
> There's still a race, it's just less likely to hit in your example.<BR>
<BR>
You're right, that did seem to work. May I ask what the need for the `sleep(1)' is? I'm trying now with another architecture - passing a message round a ring, that is slightly more unpredictable than my previous master/slace example.<BR>
<BR>
Your suggestion does work for that too, but a lot more slowly once a remote process was killed. Is there a possibility to avoid the sleep(1) ? And can you explain for me why the MPI_Iprobe has any effect on fault tolerant behaviour. It does, as you have shown. But I don't know why.<BR>
<BR>
Pavan,<BR>
<BR>
> You cannot just "refresh" MPI_COMM_WORLD by resizing it, as the process<BR>
> ranks will be completely messed up if you do that. What you really want<BR>
> to do is create a new communicator with the remaining "alive" processes.<BR>
<BR>
That's interesting, this is something I'd like to try. I can't find any compilable examples that make use of MPIX_Group_comm_create, would you be able to provide on? I tried, but wasn't sure how to create/manipulate the MPI_Group, for the 2nd parameter. Are there any code examples?<BR>
<BR>
<BR>
thanks,<BR>
<BR>
--<BR>
Rob Stewart<BR>
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