[mpich-discuss] mpich2 and stdin longer than 1024 lines

[Rajeev Thakur]

The MPD process manager provides limited buffering in mpiexec, to avoid
having to buffer waiting for applications to read, in exchange for flexible
stdin control for use in interactive debugging. Instead of large stdins, you
can open a file from rank 0 and read it. 

Rajeev



> -----Original Message-----
> From: owner-mpich-discuss at mcs.anl.gov 
> [mailto:owner-mpich-discuss at mcs.anl.gov] On Behalf Of Bryan Putnam
> Sent: Monday, October 27, 2008 8:27 AM
> To: mpich-discuss at mcs.anl.gov
> Subject: [mpich-discuss] mpich2 and stdin longer than 1024 lines
> 
> 
> Hi All,
> 
> We've noticed that when using mpich2-1.0.7, the mpi 
> application will hang 
> when using a stdin that is longer than 1024 lines.  You can easily 
> reproduce this using the famous "pi" program set up to read 
> from stdin. 
> For example using 2 processors on each of 2 nodes:
> 
> perl -e 'print "100\n" x 1023; print "0\n"' > inp
> mpdboot -n 2 -f $PBS_NODEFILE
> mpirun -np 4 ./pi < inp
> 
> works fine, while
> 
> perl -e 'print "100\n" x 1024; print "0\n"' > inp
> mpdboot -n -f $PBS_NODEFILE
> mpirun -np 4 ./pi < inp
> 
> hangs.
> 
> Note that a workaround is to do
> 
> mpirun -np 4 "cat inp | pi"
> 
> Any help on what to modify in the mpich2 scripts to fix this would be 
> appreciated.
> 
> Thanks!
> Bryan
> 
> 
> --
> Bryan Putnam
> Rosen Center for Advanced Computing, Purdue University
> Young Hall (Rm. 519)
> 302 Wood Street
> West Lafayette, IN 47907-2108
> Ph 765-496-8225 Fax 765-494-0566
> bfp at purdue.edu
> http://www.rcac.purdue.edu
> 
>