Copies of Code

[Fizzics]

Has anyone tried to run several copies of the same python code in the background? Let me explain. What I need to do is open 50 or so different folders and do operations on the stuff inside each folder. It works fine in serial, open folder1, do work, open folder2, do work etc. But this takes a long time, order of 3-4 hours. So I was trying to get it to run concurrently.

The way I was planning on doing this was by calling each instance of the python code from a bash script. Here it is for four folders.

#!/bin/sh
for i in $(seq 0 3);
do
        python calculate.py $i  &
done
wait
exit 0

The script takes the number as an argument and uses that number to open the appropriate folder.

Now here is the problem. When I run this script, folder0 is worked on correctly. The other 3 folders are not. Here is some output.

-bash-3.1$ ./test.sh 
Engage the System
Engage the System
Engage the System
Engage the System
reading `/tmp/shared/sqb/folder0/snapshot_000' ...
Error: can't open file.
allocating memory...done
Error: can't open file.
Error: can't open file.
reordering...done.
space for particle ID freed
DONE
DONE
DONE
.
.
folder0 is being worked on... 
.
.
DONE

I assume that the "Error: can't open file" is a python error. Has anyone tried to do something like this before?

Thanks for all your help

[kaarthikeyapreyan]

Check if the files that the python script manipulates are present in the corresponding folders the script is expected to work fine in that case e.g:

Dir structure
readir.py
test0/testfile0.py
test1/testfile1.py
test.sh

#!/bin/sh
for i in $(seq 0 1);
do
   python readir.py $i  &
done
wait
exit 0

The python code would just print the contents of the directory

import os
import sys

exec "os.chdir('test%s'%sys.argv[1])"
print os.listdir('.')

The script works fine for me
o/p
['testfile1.py']
['testfile0.py']