[mpich-discuss]network failure during the execution of parallel program

[Jayesh Krishna]

 Hi,
  Specifying "shm" as the channel ensures that all MPI communication (btw
the MPI processes) is done using shared memory. The error messages that
you see could be from the process launcher or the process manager.
  Do you really need to use the "-localonly" option (Specifying the option
you might end up seeing some error messages which are handled within the
library and does not effect the MPI job)? You can run your job as "mpiexec
-channel shm -n 4 myapp.exe". Let us know if you still see the error
messages (If yes, please copy-paste the error mesgs in your email)

Regards,
Jayesh

-----Original Message-----
From: owner-mpich-discuss at mcs.anl.gov
[mailto:owner-mpich-discuss at mcs.anl.gov] On Behalf Of Seifer Lin
Sent: Wednesday, May 28, 2008 2:32 AM
To: mpich-discuss at mcs.anl.gov
Subject: [mpich-discuss]network failure during the execution of parallel
program

Hi all:

I test a parallel program in a single machine with 4 processes.
The program only outputs ncpu and cpuid every 5 seconds
I use   mpiexec -localonly 4 myapp.exe
During the execution, I unplug the network line, and the program shows
some error messages like generic socket failure.

If I use mpiexec -channel shm -n 4 myapp.exe, and also unplug the network
line, the same error messages are showed again.
After the network is unplugged, I run the program again, and it doesn't
show any error messages.

It seems that mpiexec will detect the network status at the runtime even
the shm channel is selected.

My question is that for -channel shm, it means shared memory, and any
network state changed shouldn't affect the program using shared memory ?

I am really confused.

thanks,

Seifer Lin


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