Lighttpd: PHP_FCGI_CHILDREN correct value

lighttpdmemoryperformance

I'm running Lighttpd on 256MB RAM VPS (with low estimated traffic).

In order to optimize my server performances I decided to change these settings:

                    "PHP_FCGI_CHILDREN" => "1",
                    "PHP_FCGI_MAX_REQUESTS" => "20"

The reason why I set 1 child is that with setting there are 4 php_cgi processes:

2413 11336 /usr/bin/php-cgi
2415 4592 /usr/bin/php-cgi
2417 11336 /usr/bin/php-cgi
2419 27656 /usr/bin/php-cgi

If I set 4 I get >8 children. I'm wondering why and if this is ok.
Now my webserver is very fast, because I finally don't rely on swapping so massively as before.

thanks

Best Answer

As you can see in this FAQ there are three config options that control the number of mod_php processes.

PHP_FCGI_CHILDREN (defaults to 1)
max-procs (defaults to 4)
min-procs (ignored in current releases)

The formula to caluclate the initially spawned processes looks like this:

no_of_procs = max-procs * ( PHP_FCGI_CHILDREN + 1)

This means, for every procs in max-procs launch PHP_FCGI_CHILDREN workers +1 Guardian process for each parent in max-procs.

Related Solutions

Lighttpd + FCGI settings

Have a look at http://docs.djangoproject.com/en/dev/howto/deployment/fastcgi/

I followed that to get my Lighttpd + FastCGI setup working (I've included a sanitised verison of my config below for reference). You will also want to set FORCE_SCRIPT_NAME="" in your settings.py.

server.modules   += ( "mod_fastcgi" )
server.modules   += ( "mod_alias" )

$HTTP["host"] =~ "(www\.)?domain\.com" {
    fastcgi.server = (
        "/django.fcgi" => (
            "main" => (
                "host" => "127.0.0.1",
                "port" => 3000,
                "check-local" => "disable",
            )
        ),
    )

    alias.url = (
        "/admin-media" => "/path/to/django/contrib/admin/media/",
    )

    url.rewrite-once = (
        "^(/admin-media.*)$" => "$1",
        "^(/.*)$" => "/django.fcgi$1",
    )
}

Best Answer

Related Solutions

Lighttpd + FCGI settings

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