persist_backend and Apache config

Brad Fitzpatrick brad at
Wed Apr 2 15:30:41 UTC 2008

With Perlbal, use keep-alives everywhere!  Perlbal frontside, backside,
Apache frontside.

The reason that mod_perl docs say not to is because they you're limited to,
say, 50 total users to your site, even if 49 of them are just waiting 15
seconds to maybe ask for another page.

With Perlbal, Perlbal owns those 50 connections keep-alived, but keeps them
frickin' busy, and can deal with tens of thousands (or more) of idle
connections to real kept-alive clients waiting to send another request in
the future without TCP setup time.

On Wed, Apr 2, 2008 at 7:37 AM, Bill Moseley <moseley at> wrote:

> On Tue, Apr 01, 2008 at 08:16:56AM -0700, Ask Bjørn Hansen wrote:
> >
> > KeepAliveTimeout typically can be nice and high; there are no
> > particularly good reasons to shutdown the connections.  Of course the
> > difference between say 200 and 2000 is pretty small -- if the
> > connection has been idle for that long the server obviously isn't
> > getting much work anyway.   I usually use somewhere between 60 and 300.
> So, what's your recommendation on keep-alives on the front end?
> Again, all my static content is on another server.  So, for a page get
> the only request is for the content -- so there's only one request.
> The exception might be a browser that pre-fetches links -- or if the
> client is something like a spider fetching links very often.
> I assume the client Perlbal connections are very light, so the keep
> alives on the front end are not much of a consideration.
> --
> Bill Moseley
> moseley at
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