[cgiapp] Tasks after fork()'ing a CGI::Application

[Michael Peters]

Gurunandan R. Bhat wrote:

> I would like this to be as robust as possible. Currently, all I do in
> the child before launching the long-running process is close STDOUT. Is
> there any other tasks I must perform? 

Make sure you don't have have any other file handles in use. This includes 
sockets and database handles.

> Is there a CPAN module that might
> help clean up things in the child better than this? I tried Proc::Daemon
> but that closes all file descriptors inherited from the parent(including
> a few datafile descriptors that I need access to). I can of course
> re-open them from well know locations.

You really should re-open them. Strange things can happen when your system gets 
under a decent load that aren't apparent when testing or under a light load when 
you share file handles/sockets across processes like that.

> Any advice on making this method more robust would be hugely
> appreciated.

I would actually suggest that you don't fork your web process to do background 
tasks. The problem is that your web processes are generally much heavier than 
you need which means wasted resources. It also can cause scalability concerns if 
you suddenly have lots of background tasks to perform. I'd suggest you look into 
having a dedicated job queue. You could use one of the existing frameworks like 
Gearman or TheSchwartz, or you could write you own using something like POE or 
Proc::Daemon+Parallel::ForkManager.

-- 
Michael Peters
Plus Three, LP