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Parallelization with /bin/sh

I have 89 log files. The average file size is 100ish megs. I want to parse all of the logs into something else useful. Processing 9.1 gigs of logs is not my idea of a good time, nor is it a good application for a single CPU to handle. Let's parallelize it.

I abuse /bin/sh's ability to background processes and wait for children to finish. I have a script that can take a pool of available computers and send tasks to it. These tasks are just "process this apache log" - but the speed increase of parallelization over single process is incredible and very simple to do in the shell.

The script to perform this parallization is here: parallelize.sh

I define a list of hosts to use in the script and pass a list of logs to process on the command line. The host list is multiplied until it is longer than the number of logs. I then pick a log and send it off to a server to process using ssh, which calls a script that outputs to stdout. Output is captured to a file delimited by the hostname and the pid.

I didn't run it single-process in full to compare running times, however, parallel execution gets *much* farther in 10 minutes than single proc does. Sweet :)

Some of the log files are *enormous* - taking up 1 gig alone. I'm experimenting with split(1) to split these files into 100,000 lines each. The problem becomes that all of the tasks are done except for the 4 processes handling the 1 gig log files (there are 4 of them). Splitting will make the individual jobs smaller, allowing us to process them faster becuase we have a more even work load across proceses.

So, a simple application benefiting from parallelization is solved by using simple, standard tools. Sexy.