[Mongrel] mongrel garbage collection

[Steve Midgley]

At 01:19 PM 3/21/2008, mongrel-users-request at rubyforge.org wrote:
>Date: Fri, 21 Mar 2008 14:19:01 -0600
>From: "Kirk Haines" <wyhaines at gmail.com>
>Subject: Re: [Mongrel] mongrel garbage collection
>To: mongrel-users at rubyforge.org
>Message-ID:
>         <f4cd26df0803211319o491ad3c1u92ef5509c433c76b at mail.gmail.com>
>Content-Type: text/plain; charset=ISO-8859-1
>On Fri, Mar 21, 2008 at 1:23 PM, Scott Windsor <swindsor at gmail.com> 
>wrote:
>
> > I understand that the GC is quite knowledgeable about when to run 
> garbage
> > collection when examining the heap.  But, the GC doesn't know 
> anything about
> > my application or it's state.  The fact that when the GC runs 
> everything
> > stops is why I'd prefer to limit when the GC will run.  I'd rather 
> it run
> > outside of serving a web request rather then when it's right in the 
> middle
> > of serving requests.
>
>It doesn't matter, if one is looking at overall throughput.

Hi Kirk,

One thought on this - would it be possible to schedule GC to run just 
after all the html has been rendered to the client from Rails, but 
while leaving open the connection (so that mongrel is blocked on 
Rails)?

If so, it seems like if one were using something like nginx fair proxy, 
then the mongrel would be running it's garbage collection AFTER the 
client got all its html but BEFORE any new requests were sent to it.

In a fully loaded server it wouldn't matter at all, but most 
environments have a little headroom at least, so that nginx fair proxy 
would just route around the mongrel that is still running a GC at the 
end of it's Rails loop.

So total throughput for a given (non-max) volume of requests might be 
unaffected since nothing would ever pile up behind a rails process that 
has slowed down to run GC (and the client will be happy since they got 
all their html before the GC started).

I have no idea if this is meaningful, but I've been playing with some 
performance tests against mongrel + nginx fair proxy and it occurs to 
me that this might be relevant..

Best,

Steve