Running Subversion post-commit hook as a background process

Question

Because currently our Subversion post-commit hooks take way too long to execute I've been trying to speed things up.

I've been thinking about executing the actual hooks as a background process, so that the svn commit would complete before the actual hooks finish running.

So I created two files.

A post-commit.bg that does something time-consuming:

sleep 10

And the actual post-commit itself that executes the former in background:

bash post-commit.bg &

When I run post-commit from command line it finishes quickly, leaving post-commit.bg still running. But when I do svn commit it still takes 10 seconds!

Are background processes somehow disallowed by SVN or what could I be doing wrong here?

Answer 1

I just confirmed this locally. It appears to be by design:

When running hooks, svn calls apr_proc_wait

apr_proc_wait is designed to wait until all child processes exit before returning. This is to avoid zombie(unowned) processes overrunning the system.

You might have some success if you find a way to detach the process (ie, daemon mode), but I'm not sure.

You might find it better to run another process somewhere which does some work in response to a ping from svn - Hudson is my choice for this sort of thing - jobs can be triggered by a wget in a post-commit hook, or you can have it poll subversion for you, depending on what you want to do.

Answer 2

You need to redirect stderr also:

bash post-commit.bg 2>&1 &

That will detach the process from the parent process (as far as subversion is concerned) and let the client finish without waiting. I had this same problem, and that was the fix.

Answer 3

On Linux, just use nohup:

nohup sh -c 'sleep 10' &

Answer 4

I think dehmann is right. you can also register post-commit.bg to be executed as a batch process - on linux, use the 'batch' command (at) for that; but pay attention to the potential reshuffling...

Answer 5

For windows user:

This topic has already been discussed here: Running another program in Windows bat file and not create child process