Using the Swoole Extension

The PHP Swoole extension was first made available on the PHP extension C library website in December 2013. Since that time, it’s gained considerable attention. With the introduction of the JIT compiler in PHP 8, there has been a considerable amount of renewed interest in the Swoole extension as it’s fast and stable and is in a position to make PHP applications run even faster. The total number of downloads is close to six million, and the average number per month is around 50,000.

We will learn about the extension, how it’s installed, and how it’s used. Let’s first get an overview of the extension.

Examining the Swoole extension

Because the extension is written in the C language, once it’s compiled, installed, and enabled, a set of functions and classes are added to our current PHP installation. The extension leverages certain low-level features that are only available in OSs derived from UNIX, however. This means that if we are running a Windows server, the only way we can get a PHP async application that uses the Swoole extension running is by installing Windows Services for Linux (WSL) or by setting up our application to run in a Docker container on the Windows server.

One of the big advantages of PHP async is that the initial block of code gets loaded immediately and stays in memory until the asynchronous server instance stops. This is the case when using the Swoole extension. In our code, we create an asynchronous server instance that effectively turns PHP into a continuously running daemon listening on the designated port. This is also a disadvantage, however, because if we make changes to our program code, the changes are not recognized by the async server instance until we reload it.

One of the great features of the Swoole extension is its coroutine support. What this means, in real-life terms, is that we don’t have to perform major surgery on applications written using the synchronous programming model. Swoole will automatically pick out blocking operations, such as filesystem access and database queries, and allow these operations to be placed on hold while the rest of the application proceeds. Because of this support, we can often simply run the synchronous application using Swoole, resulting in an immediate performance boost.

Another really great feature of the Swoole extension is Swoole\Table. This feature lets us create, entirely in memory, the equivalent of a database table that can be shared between multiple processes. There are many possible uses for such a construct, and the potential performance gain is truly staggering.

The Swoole extension has the ability to listen for User Datagram Protocol (UDP) ...