PHP-FPM settings tutorial. max_servers, min_servers, etc.

You need to know three things about your server before you change PHP FPM’s settings:

  1. How many cores does your server have?
  2. The amount of memory (RAM) on your server.
  3. How much memory does the average PHP process consume on your server?

How many cores does your server have?

To find out how many cores your server has, run the following command:

When you run the Linux command above, you will get something like “Cores = 4”.

Jot that figure down because it’s important.

How much memory does your server have?

You should already know how much memory your server has. The real question here is: “How much memory do you want to give PHP?”

You have to take into account the fact that your server might be also running NGINX, Apache or MySQL. How much memory are these other processes consuming? If you have 8GB of RAM and the other processes on your machine are consuming 2GB, that leaves you with 6GB – or 5GB if you want to play it safe and leave some free.

Figure out how much memory you want to give PHP and jot that down. In my case, I had 4GB that I could allocate to PHP.

On average, how much memory does each PHP process consume?

This will depend on your application and your version of PHP. Older versions of PHP tend to consume more memory than PHP 7.

Run the command below to get a general idea of how much memory each PHP FPM process is consuming.

Note that the command above above is looking for a process called php-fpm7.2. The PHP process on your server might be called something different. To find out the name of your PHP process, use the top command. When you run the top command, you will probably see one of the following processes:

  • php-fpm
  • php5-fpm
  • php7.0-fpm
  • php7.1-fpm
  • php7.2-fpm

When I ran the command above, I got 29M. i.e. Each php-fpm7.2 process on my server consumes about 29MB in RAM.

The configuration settings.

I now have three important pieces of information:

  • My server has 4 cores.
  • I can allocate about 4GB of RAM to PHP.
  • Each PHP FPM process on my server consumes about 29MB of memory. On older versions of PHP, you will probably see that each process consumes a lot more than that. I was reaching about 90MB per process when I was running the exact same application on PHP 5.5.

Now it is time to edit the www.conf file, which is situated in the pool.d directory. On my server, it was located at:

/etc/php/7.2/fpm/pool.d/www.conf

On your machine, the location might be slightly different.

There are 4 configuration values that we are going to change in the www.conf file:

  • pm.max_children
  • pm.start_servers
  • pm.min_spare_servers
  • pm.max_spare_servers

pm.max_children

To get a good value for this, you should take the memory that you want to allocate to PHP FPM and divide it by the average memory that is consumed by each PHP FPM process.

In my case, I want to allocate 4GB (4000MB) and each process consumes about 29MB.

Divide 4000 by 29 and you get around 138.

So I set pm.max_children to 138.

If you have 8000MB to spare and your PHP consumes about 80MB per process, then that will be: 8000 / 80 = 100.

pm.start_servers

For pm.start_servers, I multiply the number of cores that I have by 4.

4 x 4 = 16

So I set pm.start_servers to 16.

If you have 8 cores, then it will be: 4 x 8 = 32.

pm.min_spare_servers

For pm.min_spare_servers, multiply the number of cores that you have by 2.

In my case, that is 2 x 4 = 8.

So I set pm.min_spare_servers to 8.

pm.max_spare_servers

For pm.max_spare_servers, multiply the number of cores on your server by 4.

On my machine, that is 4 x 4 = 16.

So I set pm.max_spare_servers to 16, the same value that I used for pm.start_servers.

Restart PHP FPM.

For these changes to take affect, you will need to restart PHP FPM. Below, I have included a number of service restart commands that might apply to your setup. Select the correct one and run it.

Anyway, hopefully you found this guide useful!

A better way to run PHP-FPM

If you search the web for PHP-FPM configurations, you’ll find many of the same configurations popping up. They nearly all use the ‘dynamic’ process manager and all assume you will have one master process for running PHP-FPM configurations. While there’s nothing technically wrong with that, there is a better way to run PHP-FPM.

In this blogpost I’ll detail;

  1. Why ‘dynamic’ should not be your default process manager
  2. Why it’s better to have multiple PHP-FPM masters

.. If you’re working on a high performance PHP setup, the ‘ondemand’ PM may not be for you. In that case, it’s wise to pre-fork your PHP-FPM processes up to the maximum your server can handle. That way, all your processes are ready to serve your requests without needing to be spawned first. However, for 90% of the sites out there, the ondemand PHP-FPM configuration is better than either static or dynamic.

How to reduce PHP-FPM (php5-fpm) RAM usage by about 50%

I became aware of what an alternative configuration would do after reading an article titled A better way to run PHP-FPM. It was written about a year ago, so it’s kinda disappointing that I came across it while searching for a related topic just last night. If you run your own server and use PHP with PHP-FPM, you need to read that article.

After I read it, I changed the pm options in the pool configuration file to these:

The major change was setting pm = ondemand instead of pm = dynamic. And the impact on resource usage was drastic. Here, for example, is the output of

Related Post:  Eyes in the Sky: The Rise of Gorgon Stare and How It Will Watch Us All

free mt after reloading php5-fpm:

Compared to the output before, that’s more than a 50% drop in RAM usage. And the reason became obvious when I viewed top again:

Did you notice that there are no child processes? What happened to them? That’s what setting pm = ondemand does. A child process is spawned only when needed. After it’s done its job, it remains idle for 10 seconds (pm.process_idle_timeout = 10s) and then dies.

So what I have is a simple modification to the default PHP-FPM settings that saved me more than 50% of RAM. Sure, the server hasn’t come under heavy traffic, but I think it can withstand a reasonably heavy traffic, considering that it only has 512 MB of RAM. And with Nginx microcaching configured, I think it will do very well. There are other aspects of PHP-FPM and Percona MySQL that I’ve not optimized yet, so stay tuned. This was just to pass on a little tip that I found useful.

pyronos: Simple and sweet load testing module.

Creates a “results” folder in the current directory to store all of the load testings.

# Simple usage.
pyronos  get 25 simple

# Send head request.
pyronos  head 25 simple

# Dump logs.
pyronos  get 25 simple -d

# Send requests sequentially.
pyronos  get 25 simple -s

# Print progress of sequential requests.
pyronos  get 25 simple -s -p

$ pyronos -h
usage: pyronos [-h] [-f {simple,stem,step}] [-o {csv,json,yml}] [-s] [-p] [-d]
               [-v]
               url {get,head,options,delete,post,put} num_of_reqs

Simple and sweet load testing module.

positional arguments:
  url                   url of website
  {get,head,options,delete,post,put}
                        http method
  num_of_reqs           number of requests

optional arguments:
  -h, --help            show this help message and exit
  -f {simple,stem,step}, --figure {simple,stem,step}
                        type of figure
  -o {csv,json,yml}, --output {csv,json,yml}
                        type of output
  -s, --sequential      sequential requests
  -p, --print-progress  print progress
  -d, --dump-logs       dump logs
  -v, --version         show program's version number and exit

5.2.1 Storing counters in Redis

In order to update counters, we’ll need to store the actual counter information. For each counter and precision, like site hits and 5 seconds, we’ll keep a HASH that stores information about the number of site hits that have occurred in each 5-second time slice. The keys in the hash will be the start of the time slice, and the value will be the number of hits. Figure 5.1 shows a selection of data from a hit counter with 5-second time slices.

As we start to use counters, we need to record what counters have been written to so
that we can clear out old data. For this, we need an ordered sequence that lets us iterate
one by one over its entries, and that also doesn’t allow duplicates. We could use a LIST
combined with a SET, but that would take extra code and round trips to Redis. Instead,
we’ll use a ZSET, where the members are the combinations of precisions and names that
have been written to, and the scores are all 0. By setting all scores to 0 in a ZSET, Redis
will try to sort by score, and finding them all equal, will then sort by member name. This gives us a fixed order for a given set of members, which will make it easy to sequentially
scan them. An example ZSET of known counters can be seen in figure 5.2.

Figure 5.1A HASH that shows the number of web page hits over 5-second time slices around 7:40 a.m. on May 7, 2012
Figure 5.2A ZSET that shows some known counters

WordPress: Redis Object Cache

A persistent object cache backend powered by Redis. Supports PredisPhpRedis (PECL), HHVM, replication, clustering and WP-CLI.

To adjust the connection parameters, prefix cache keys or configure replication/clustering, please see Other Notes.

Forked from Eric Mann’s and Erick Hitter’s Redis Object Cache.

REDIS CACHE PRO

business class Redis object cache backend. Truly reliable, highly optimized, fully customizable and with a dedicated engineer when you most need it.

  • Rewritten for raw performance
  • WordPress object cache API compliant
  • Easy debugging & logging
  • Fully unit tested (100% code coverage)
  • Secure connections with TLS
  • Seamless WP CLI & Debug Bar integration
  • Optimized for WooCommerce, Jetpack & Yoast SEO

WordPress Performance – Breaking It Down by HTTP Requests

1. Disable Emojis with Code#

The first way to disable emojis is you can put the following code into your functions.php file.

/**
 * Disable the emoji's
 */
function disable_emojis() {
    remove_action( 'wp_head', 'print_emoji_detection_script', 7 );
    remove_action( 'admin_print_scripts', 'print_emoji_detection_script' );
    remove_action( 'wp_print_styles', 'print_emoji_styles' );
    remove_action( 'admin_print_styles', 'print_emoji_styles' );
    remove_filter( 'the_content_feed', 'wp_staticize_emoji' );
    remove_filter( 'comment_text_rss', 'wp_staticize_emoji' );
    remove_filter( 'wp_mail', 'wp_staticize_emoji_for_email' );
    add_filter( 'tiny_mce_plugins', 'disable_emojis_tinymce' );
}

add_action( 'init', 'disable_emojis' );

/**
 * Filter function used to remove the tinymce emoji plugin.
 *
 * @param    array  $plugins
 * @return   array             Difference betwen the two arrays
 */
function disable_emojis_tinymce( $plugins ) {
    if ( is_array( $plugins ) ) {
        return array_diff( $plugins, array( 'wpemoji' ) );
    } else {
        return array();
    }
}


Step 6. Host Google Fonts#

Next, if we look closer we can see there are 4 requests being generated to fonts.gstatic.com. And this is to load Google fonts, which is included in the default WordPress theme. In our example, it is loading different font weights for Merriweather and Montserrat.

https://fonts.googleapis.com/css?family=Merriweather%3A400%2C700%2C900%2C400italic%2C700italic%2C900italic%7CMontserrat%3A400%2C700%7C&subset=latin%2Clatin-ext

https://fonts.gstatic.com/s/montserrat/v7/IQHow_FEYlDC4Gzy_m8fcoWiMMZ7xLd792ULpGE4W_Y.woff2

https://fonts.gstatic.com/s/merriweather/v13/RFda8w1V0eDZheqfcyQ4EOgdm0LZdjqr5-oayXSOefg.woff2

https://fonts.gstatic.com/s/montserrat/v7/zhcz-_WihjSQC0oHJ9TCYPk_vArhqVIZ0nv9q090hN8.woff2

It always better to reduce the number of external DNS lookups and also focus on having a single HTTP/2 connection if possible. Every external lookup introduces its own set of latency issues, content download times, TLS negotiations, etc. So what we are going to do is move the Google fonts to our CDN. This way they load from the same place as the rest of our assets.

You can check out our in-depth tutorial on how to migrate Google Fonts to your CDN. This can also be used to simply host them directly on your web server as well, if you aren’t using a CDN. We quickly download the following Google fonts from https://google-webfonts-helper.herokuapp.com and host them on our server in a folder called “fonts.”

 

Step 7. Disable Gravatars#

As you can see we are almost down to a single HTTP/2 connection with no external DNS lookups. The only thing left is that call to gravatar.com. Thankfully they are using HTTP/2 now, but unless you really want avatars, you can disable them.

gravatar http request

This can easily be remove by un-checking the “show avatars” in the discussion setting of your WordPress dashboard.



By removing the call to gravatar.com we are now down to 11 HTTP requests and are using a single HTTP/2 connection for external assets on our CDN.