From: Robert Gleeson <rob@...>
Date: 2010-03-28T17:31:54+09:00
Subject: Re: non-blocking calls to external APIs

David Collier wrote:
> hi -
> 
> sure this is becoming a more common issue for many people - from within
> a web-app how to interact with other systems in a non-blocking way. ie i
> dont need to wait for a response from the other system in the cycle of
> the same user request/response.
> 
> i need to send some logging information off to another system, via
> rest/http.
> in a rails app we're currently using delayedJob, which stores the events
> to the DB, and another process sends them. this is a pretty heavy
> process.
> 
> a simplistic way would be just using  system "curl &" but that will
> spawn a system process. not sure about the risks involved with that -
> this means one NgInx/rails instance will have to wait for that to
> complete, and maybe run into memory issues.
> 
> Are there any ways to use the net/http library to "fire and forget" a
> call?
> or perhaps a simple implementation using threads, that will be less
> resource intensive than "curl &"
> 
> thanks...
> 
> /dc

All the other suggestions are great, and you should give 'em some 
consideration.
I'd mention fork() as well, though, since most UNIX-like 
distributions(if not all? I'm just not 100%) implement a copy-on-write 
fork(), reducing the overhead people sometimes associate with fork().

I'd add as a note that sharing data between two processes isn't straight 
forward, you might need to look at IO.pipe but if you don't need to send 
data back or have data available in your subprocess after a call to 
fork() you should be fine.

Don't forget Process.wait and/or Process.detach to avoid collectin' 
zombies.

Thanks,
Rob
-- 
Posted via http://www.ruby-forum.com/.