OPcache

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The standard OPcache extension is strongly recommended; since Moodle 2.6, it is the only solution officially supported by PHP developers. The benefits are increased performance and significantly lower memory usage. However, opcode caching extensions (including OPcache, eAccelerator and APC) aren't compatible with servers configured to use some common types of high-security PHP handlers such as suPHP (the default on WHM / cPanel Linux servers).

Installation

The OPcache extension is distributed as part of PHP 5.5.0 and later. It is available also for older stable PHP releases from PECL under the original name ZendOPcache.

NOTE: If you are running PHP 5.3 or 5.4 you can safely ignore the Environment Check message about OpCache. Nonetheless, it might be useful to upgrade Operating System/PHP and get to 5.5 or newer; as there have been all sorts of problems described on PHP 5.2 and 5.3, and upgrading PHP turned out to be the easier solution.

Configuration

PHP.ini settings:

[opcache]
opcache.enable = 1
opcache.memory_consumption = 64
opcache.max_accelerated_files = 8000
opcache.revalidate_freq = 60

; Required for Moodle
opcache.use_cwd = 1
opcache.validate_timestamps = 1
opcache.save_comments = 1
opcache.enable_file_override = 0

; If something does not work in Moodle
;opcache.revalidate_path = 1 ; May fix problems with include paths
;opcache.mmap_base = 0x20000000 ; (Windows only) fix OPcache crashes with event id 487

; Experimental for Moodle 2.6 and later
;opcache.fast_shutdown = 1
;opcache.enable_cli = 1 ; Speeds up CLI cron
;opcache.load_comments = 0 ; May lower memory use, might not be compatible with add-ons and other apps.

When using non-Windows platforms, you have to use the zend_extension configuration to load the OPcache extension into PHP by adding to php.ini.

zend_extension=/full/path/to/opcache.so

When using IIS you will need PHP 5.5 and you will need to add the extension for opcache under the ExtensionList section of the php.ini file. For PHP 5.3 and 5.4 you can download the binaries separately from [1] and you will also need to enter full absolute path to the module dll in php.ini.

[ExtensionList]
...
zend_extension=php_opcache.dll
max_accelerated_files

From: php.net max-accelerated-files

  • The maximum number of keys (and therefore scripts) in the OPcache hash table. The actual value used will be the first number in the set of prime numbers { 223, 463, 983, 1979, 3907, 7963, 16229, 32531, 65407, 130987 } that is bigger than the configured value. Only numbers between 200 and 100000 are allowed.

As Moodle 3.0 contains over 8000 php files it is recommended above that opcache.max_accelerated_files should be set to 8000 to accommodate this (16229 will actually be used as per the explanation above).

If many additional plugins are installed so that your total PHP files exceed 16229 then the next most suitable value for max_accelerated_files should be used.

See also

Forum discussions: