To: pgsql-performance@postgresql.org
From: Mark Stosberg <mark@summersault.com>
Subject: Re: recommendations for web/db connection pooling or DBD::Gofer
	reviews
Date: Thu, 10 Apr 2008 17:28:51 -0400
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	<op.t9bc9ekpcigqcu@apollo13.peufeu.com>
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>     Under heavy load, Apache has the usual failure mode of spawning so 
> many threads/processes and database connections that it just exhausts 
> all the memory on the webserver and also kills the database.
>     As usual, I would use lighttpd as a frontend (also serving static 
> files) to handle the large number of concurrent connections to clients, 
> and then have it funnel this to a reasonable number of perl backends, 
> something like 10-30. I don't know if fastcgi works with perl, but with 
> PHP it certainly works very well. If you can't use fastcgi, use lighttpd 
> as a HTTP proxy and apache with mod_perl behind.
>     Recipe for good handling of heavy load is using an asynchronous 
> server (which by design can handle any number of concurrent connections 
> up to the OS' limit) in front of a small number of dynamic webpage 
> generating threads/processes.

Thanks for the response.

To be clear, it sounds like you are advocating solving the problem with 
scaling the number of connections with a different approach, by limiting 
the number of web server processes.

So, the front-end proxy would have a number of max connections, say 200, 
  and it would connect to another httpd/mod_perl server behind with a 
lower number of connections, say 20. If the backend httpd server was 
busy, the proxy connection to it would just wait in a queue until it was 
available.

Is that the kind of design you had in mind?

That seems like a reasonable option as well. We already have some 
lightweight Apache servers in use on the project which currently just 
serve static content.

    Mark