Let’s explore the methods to clear PHP Opcache in this article. At Bobcares, with our Server Management Services, we can handle your PHP issues.

How to clear PHP Opcache?

Opcache is a feature of PHP that allows it to store precompiled bytecode in shared memory. It prevents PHP scripts from being loaded and parsed on every request. To refresh the cached code in PHP, we need to flush the Opcache. The APC cache has been replaced by Opcache in PHP 5.5, and APC now only exists as a user key/value cache rather than a bytecode cache.

“How we run PHP?” determines the manner in which we clear the Opcache.In this article, we will see some of the methods to clear PHP Opcache.

1. Determine the PHP method

To clear the PHP Opcache, we must first determine the PHP method so that we can use the best suitable method to clear the Opcache. In order to clear PHP Opcache in a uniform way, create a new PHP file in the docroot called  flush_cache.php.

<?php
opcache_reset();
?>

While we need to clear the Opcache, simply navigate to the flush_cache.php file. For the entire Opcache, the file will call opcache_reset(). We don’t need to worry about the running process because the execution of the flush_cache.php files doesn’t affect it.

2. PHP running as CGI or FastCGI

CGI or FastCGI PHP Opcache Flushing is extremely simple because the cache is flushed on every request. FastCGI creates a new php-cgi process for each request and lacks a parent PHP process to store Opcache results in.

In fact, running Opcache in a CGI or FastCGI model would degrade performance because the Opcache is in the FastCGI process on every request (the default behavior if the Opcache extension is enabled), but that cache is destroyed as soon as that process dies after completing the request. Storing the Opcache requires a few CPU cycles and is an effort that cannot be repaid later.

3. PHP running at the CLI

Opcache is not present in any of the PHP scripts we run from the command line. However, we can enable it and PHP can attempt to store its Opcache in memory. The cache will disappear as soon as the CLI command terminates. So simply restart the PHP command to clear the Opcache on CLI. It’s usually as simple as CTRL+C to abort and restart the command.

4. Apache running as mod_php

We can run PHP on Apache by embedding a module within the Apache webserver. PHP is normally run by the same user as the Apache webserver. In a mod_php scenario, we can either reload or restart the Apache webserver to flush the Opcache.

$ service httpd reload
$ apachectl graceful

A reload is better than a restart as the latter one is bothersome as it kills all active HTTP connections.

5. PHP running as PHP-FPM

We can send a reload to the PHP-FPM daemon if we run the PHP as PHP-FPM. The reload will force the Opcache to be rebuilt on the first incoming request by flushing it.

$ service php-fpm reload

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Conclusion

In this article, we have seen the different methods provided by our Support team to clear PHP Opcache easily.