PHP worker

A PHP worker (sometimes referred to as a PHP process or child process, or in relation to max_children log entries) is the backend server process that handles the tasks that generate web pages your visitors see when they load up your site.

Most sites on Flywheel have multiple PHP workers working concurrently. The number of available workers is variable based on several considerations, such as the site’s hosting plan, the type of content displayed on the site, the number of visitors, and other factors.

PHP workers and site issues

When PHP workers get overwhelmed with requests, they cannot process them all, which can result in slower performance or even server (5xx) errors.

There are several ways to remedy issues related to PHP workers:

• ensure the site is caching as much as possible
• ensure the site is developed optimally
• reduce the number of requests hitting the site via plugins/themes/services
• reduce the number of calls to external sites
• increase PHP workers

Waiters at a restaurant analogy

A helpful analogy to illustrate PHP workers is waiters at a restaurant.

Each waiter (PHP worker) at the restaurant (website) is serving specific diners (site visitors), going back and forth between the kitchen (web server) and the diner to deliver food orders (web pages). In addition, the waiter could be performing background tasks, such as washing dishes or putting out menus (adding tables to the site database).

If the restaurant gets too busy, the waiters will have to prioritize certain orders (processes) because they can only do one thing at a time. This could cause a backlog to pile up, which could cause diners to leave the restaurant (process failure).

How Flywheel manages PHP workers

Flywheel plans are not assigned a set amount of PHP workers – these can be adjusted as needed to ensure site performance (within plan parameters). To help with performance, Flywheel’s FlyCache feature drastically decreases the number of server requests each PHP worker must complete, which helps your sites remain stable and run faster.

Still need help?

If your site is having issues and you suspect it’s related to PHP workers, our Happiness Engineers would be glad to take a look!