Nginx – is anyway to use memcached with nginx on a post request

memcachednginx

2.1, i am also using the amazon elastic cache service (its a memcached server)

Nginx has a clever feature that uses memcached for common get request, but if is a post request dont use memcached, is anyway to disable this feature?

Here is my configuration;

location /{
    set_md5  $memcached_key "http://$server_name$uri";
    memcached_pass cacheviews.bsd7na.0001.use1.cache.amazonaws.com:11211;
    default_type text/html;
    add_header Content-Encoding gzip;
    error_page 405 404 = @fallback;
}

location @fallback{
    internal;
    gzip_types text/css text/plain application/atom+xml application/x-javascript;
    gzip_vary on;
    #  stuff to do a normal render of the page
}

Best Answer

When you get POST request, it is supposed to change some objects in your backend's storage (database), which depends on the logic of your application. So, NGINX just has no idea about what actually must be done in your application and simply does not try to cache any POST request, redirecting them directly to your backend.

Meanwhile, GET requests are supposed only to read data, without any writing - so, it can be easily cached, because every time the result of reading would be the same.

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I looked at the nginx error logs and found that it was trying to serve the media from /var/django/myproject/site_media/site_media instead of /var/django/myproject/site_media --weird.

I changed root /var/django/myproject/site_media; to root /var/django/myproject; and it works now.

Nginx – Configure php5-fpm for many concurrent users

I suspect your varnish cache is not caching anywhere near enough of the hits

here's what I would do in your situation:

Lower php max children to 100 or even 50 (if varnish does its job properly you don't need them) also remove the max requests line to allow the php processes not to respawn too quickly and thus prevent APC from being cleared too quickly which is also bad

also IF is not good according to nginx - http://wiki.nginx.org/IfIsEvil

I would change this line:

            if (!-e $request_filename) {
                    rewrite ^(.+)$ /index.php?q=$1 last;
            }

to:

try_files $uri $uri/ /index.php?$args;

If your version of nginx supports it (pretty certain if your nginx version is > 0.7.51 then it supports it)

you should also look at inserting the w3tc nginx rules direct into your vhost file to enabled proper disk enhanced caching of pages (which is faster than APC caching with nginx)

Take a look at the following varnish vcl which I use for sites - you will need to read through and edit a few things for your website - it also assumes that its only WP sites on the server and only 1 site on the server, it can easily be modified for more sites (take a look at the cookie section)

generic vcl: https://gist.github.com/b7332971a848bcb7ecef

With this config I would argue to remove fastcgi_cache to prevent any possible issues with a cache-chain occurring whereby trying locate any stray stale cache entries is more difficult

also tell w3tc that varnish is at 127.0.0.1 and it will purge it for you ;)

I deployed this to a server on Wednesday evening (with a few domain specific modifications) that was handling 2500 active site visitors it reduced load to less than 1 and the approx number of running php children was around 10-20 (this number does depend on number of logged in users and other factors like cookies) this server did have much more ram but the principle is the same, you should be able to easily handle the number of visitors you get at peaks

Best Answer

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