Varnish with mod prefork vs mpm worker with mod-fcgid

[Dridi Boukelmoune]

Hi,

I have no idea whether this could help but I had trouble with CGI in
the past because of headers being renamed or rewritten.

An RFC sample:
The header data may be presented as sent by the client, or may be
rewritten in ways which do not change its semantics. If multiple
headers with the same field-name are received then they must be
rewritten as a single header having the same semantics.
http://tools.ietf.org/html/draft-robinson-www-interface-00

So basically, I had trouble with headers not being seen because they
were renamed, and thus ignored by the application which changed its
behavior.

Best Regards,
Dridi

On Wed, Feb 27, 2013 at 8:51 AM, Daniel Schledermann
<varnish at ds.schledermann.net> wrote:
> Den 27-02-2013 01:52, Stephen Strickland skrev:
>
> When I was using mpm-preform varnish worked great with a high hit rate, but
> the server kept getting oom errors.
>
>
> Yes, mpm_prefork can be pretty memory intensive with modern CMS'es.
>
>
>
>
> From: nick tailor [mailto:nick.tailor at gmail.com]
> Sent: Tuesday, February 26, 2013 7:50 PM
> To: Mark Strickland
> Cc: varnish-misc at varnish-cache.org
> Subject: Re: Varnish with mod prefork vs mpm worker with mod-fcgid
>
>
>
> I have heard of others having similar issue with same setup.
>
>
>
> Generally they use mpm-prefork or mod fcgi with varnish. I have heard using
> Nginx with varnish is the way to go.
>
>
>
> What I would do, is disable modfcgi and see if it changes. If it does you
> know the problems lies in the settings.
>
>
>
>
>
> It sounds like you should sanitize the output headers from Apache. You might
> have a high number of hit_for_pass. That is the only reasonable way that the
> low level server setup should be able to influence caching performance.
>
> But a better advide might be to use both Apache with mpm_prefork and NGINX
> on the site. Configure varnish to split the traffic and use NGINX for static
> files and Apache mpm_prefork for PHP requests only. That way you can
> configure the prefork with real conservative settings to only have a limited
> number of apache-processes, and maybe set MaxRequestsPerChild to avoid
> excessive ballooning of PHP memory. The majority of the request will go to
> NGINX, which do not use much memory in any case. That way you can keep
> maximum compatibility with PHP-code and at the same time avoid oom problems.
>
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