[maker-devel] Running mpi_maker in the background

[Barry Moore]

I just ran across an interesting problem running mpi_maker in the  
background on a single machine and I thought I report the solution to  
the list so that it gets in the archives.  I'm sure Carson has already  
run across this, and may have come up with an better - or at least an  
alternate solution.  So Carson let us know if there is a better way  
here and if not we should probably get this in the MAKER docs at some  
point.

The problem presented itself as our system drive filling up as MAKER  
ran.  I was running MAKER (in terms of output and TMP files) on a  
large partition with 100s of GB of space.  However the system drive  
(65GB) kept filling up every time MAKER ran for more than a few  
hours.  As I would delete files from that drive it would just fill  
back up again.  Hao finally found the offending file which was /var/ 
log/messages - it was being filled with system messages like this:

Oct 11 20:03:12 derringer python2.4:  
mpiexec_derringer.genetics.utah.edu (handle_stdin_input 1067): stdin  
problem; if pgm is run in background, redirect from /dev/null
Oct 11 20:03:12 derringer python2.4:  
mpiexec_derringer.genetics.utah.edu (handle_stdin_input 1068):      
e.g.: mpiexec -n 4 a.out < /dev/null &

This was easily consuming 10s of GB per day of drive space.

The best explanation and solution that I found was here:

http://www.mail-archive.com/meep-discuss@ab-initio.mit.edu/msg01752.html

Basically that link tells you that "Running an MPI job in the  
background is supported only when stdin is redirected" and so to run  
mpi_maker in the background you should do something like this:

nohup mpiexec -n 4 mpi_maker < /dev/null 2> maker.error &

Carson, have you seen this before?  I guess this is a separate issue  
from the MPI_Init issue that was solved internally within mpi_maker  
with:

push @ARGV, 'null';