{"id":2565834,"date":"2020-07-14T10:27:00","date_gmt":"2020-07-14T08:27:00","guid":{"rendered":"https:\/\/wp-rocket.me\/?p=2565834"},"modified":"2024-08-07T14:15:31","modified_gmt":"2024-08-07T12:15:31","slug":"best-php-accelerators","status":"publish","type":"post","link":"https:\/\/wp-rocket.me\/blog\/best-php-accelerators\/","title":{"rendered":"What Are The Best PHP Accelerators?"},"content":{"rendered":"

PHP accelerators substantially improve the performance of PHP-based software such as WordPress. Running high traffic sites powered by PHP applications is possible only due to PHP accelerators. Their performance benefits vary widely as it depends on multiple factors, including other optimizations that you may need to apply on your site. <\/p>

In this article you\u2019ll learn how PHP accelerators work, why you need them, which PHP accelerators are the best for your WordPress site, and how you can install and configure them.<\/p>

Excited? Let\u2019s get started!<\/p>

What are PHP Accelerators?<\/h2>

A PHP accelerator is a PHP extension that improves the performance of PHP apps. These extensions work by caching opcode<\/strong> (or operation code) generated by PHP files. For this reason, PHP accelerators are also referred to as Opcode Caching<\/strong>. <\/p>

\"How
How a PHP accelerator (or Opcode Caching) works<\/figcaption><\/figure>

PHP scripts are written in human readable syntax, but a server (or a central processing unit) cannot understand this code directly. It needs to be converted into a format the server can read directly. This is where Opcode comes in. <\/p>

Opcode<\/em> is part of the machine language instruction that directs the server on what operations to perform. Generally, these instructions are fairly simple, like adding two numbers or concatenating two or more strings. Other parts of machine language instructions include operands<\/em>, items that the opcode manipulates.<\/p>

Every time a user requests something on your site, generating the opcode from PHP scripts can be highly taxing on your webserver. First, the scripts need to be tokenized and parsed to generate an abstract syntax tree (AST), which is then compiled to create the opcode.  <\/p>

In some extreme cases, this process can bring your website to a crawl for many users. If the number of requests is large, then the server timeouts for a lot of users, locking them out from accessing the website altogether.<\/p>

You can bypass this problem by storing the opcode as a cache (OpCache) after it\u2019s generated. You can then serve it directly to all subsequent users without getting the server involved. This is exactly what a PHP accelerator does.<\/p>

It\u2019s not unusual to see a WordPress site speed up by two to three times<\/a> (or more) after installing and configuring a PHP accelerator.<\/p>

The Best PHP Accelerators<\/h2>

PHP was launched in 1995, making it one of the oldest surviving server-side languages today. Throughout its lifetime there have been a lot of accelerators (opcode caching) implemented for it, but for server setups that run on Linux, there\u2019s primarily only one solution that\u2019s well-maintained and useful: PHP OPcache<\/strong>.<\/p>

For PHP apps running on Windows and Windows Server, there\u2019s an alternative PHP accelerator called Windows Cache Extension for PHP<\/strong>. Plus, there are many extensions to add features to PHP\u2019s built-in opcode caching. I\u2019ll cover all of them in this article.<\/p>

PHP OPcache (Zend OPcache)<\/h3>

PHP OPcache extension makes PHP code to execute faster through opcode caching and other optimization techniques. It\u2019s bundled along with PHP 5.5 and later versions. <\/p>

PHP OPcache is also called Zend OPcache since it\u2019s an implementation of Zend\u2019s opcode caching extension<\/a>. Zend kept this extension proprietary until PHP 5.5 was released. Hence, for many users Alternative PHP Cache (APC) was the go-to solution for opcode caching in PHP.  <\/p>

After Zend open sourced the code for their opcode caching and released it as an extension called Zend OPcache, PHP 5.5 made it part of its core and has been using it as the default opcode caching solution ever since. <\/p>

\"PHP
PHP OPcache works by storing the opcode cache in shared memory<\/figcaption><\/figure>

PHP OPcache improves performance by storing the precompiled bytecode in the server\u2019s shared memory when any PHP script is executed for the first time. This eliminates reading and compiling PHP code for future access. PHP OPcache also applies additional bytecode optimization patterns to make PHP code execution faster.<\/p>

APC User Cache (APCu)<\/h4>

Alternative PHP Cache (APC) is a free and an open source PHP accelerator. Like Zend OPcache, it\u2019s mainly designed to cache the PHP opcode output in the server\u2019s shared memory. Since it has always been FOSS, it was the most popular opcode caching solution for PHP until a few years ago. <\/p>

After PHP OPcache became a part of PHP 5.5, APC\u2019s development slowed down considerably and is considered dead now. However, some APC features are still not available in PHP OPcache. One of them is the userland shared memory cache functionality. It\u2019s also referred to as \u201cin memory data caching.\u201d<\/p>

To address this issue, the APC developers stripped it of all its opcode caching features and released it as a separate extension called APCu<\/a>. It adds support for userland caching of PHP variables.  <\/p>

You can also install the APCu Backwards Compatibility Module<\/a> to use APCu as a drop in replacement for APC in modern versions of PHP.<\/p>

You\u2019ll learn later how to enable and configure PHP OPcache and APCu on your server.<\/p>

Windows Cache Extension for PHP<\/h3>

Windows Cache Extension for PHP is a PHP accelerator that speeds up PHP software on Windows and Windows Server. It doesn\u2019t include support for opcode caching as PHP already includes it in its core, but it includes 4 unique types of cache: <\/p>