Symfony is fast, right out of the box. However, you can make it faster if you optimize your servers and your applications as explained in the following performance checklists.
Production Server Checklist¶
- Use the OPcache byte code cache
- Configure OPcache for maximum performance
- Don’t check PHP files timestamps
- Configure the PHP realpath Cache
- Optimize Composer Autoloader
Install APCu Polyfill if your Server Uses APC¶
If your production server still uses the legacy APC PHP extension instead of OPcache, install the APCu Polyfill component in your application to enable compatibility with APCu PHP functions and unlock support for advanced Symfony features, such as the APCu Cache adapter.
Use the OPcache Byte Code Cache¶
OPcache stores the compiled PHP files to avoid having to recompile them for every request. There are some byte code caches available, but as of PHP 5.5, PHP comes with OPcache built-in. For older versions, the most widely used byte code cache is APC.
Configure OPcache for Maximum Performance¶
The default OPcache configuration is not suited for Symfony applications, so it’s recommended to change these settings as follows:
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; php.ini ; maximum memory that OPcache can use to store compiled PHP files opcache.memory_consumption=256 ; maximum number of files that can be stored in the cache opcache.max_accelerated_files=20000
Don’t Check PHP Files Timestamps¶
In production servers, PHP files should never change, unless a new application version is deployed. However, by default OPcache checks if cached files have changed their contents since they were cached. This check introduces some overhead that can be avoided as follows:
; php.ini opcache.validate_timestamps=0
After each deploy, you must empty and regenerate the cache of OPcache. Otherwise you won’t see the updates made in the application. Given than in PHP, the CLI and the web processes don’t share the same OPcache, you cannot clear the web server OPcache by executing some command in your terminal. These are some of the possible solutions:
- Restart the web server;
- Call the
opcache_reset()functions via the web server (i.e. by having these in a script that you execute over the web);
- Use the cachetool utility to control APC and OPcache from the CLI.
Configure the PHP realpath Cache¶
When a relative path is transformed into its real and absolute path, PHP caches the result to improve performance. Applications that open many PHP files, such as Symfony projects, should use at least these values:
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; php.ini ; maximum memory allocated to store the results realpath_cache_size=4096K ; save the results for 10 minutes (600 seconds) realpath_cache_ttl=600
Optimize Composer Autoloader¶
The class loader used while developing the application is optimized to find
new and changed classes. In production servers, PHP files should never change,
unless a new application version is deployed. That’s why you can optimize
Composer’s autoloader to scan the entire application once and build a “class map”,
which is a big array of the locations of all the classes and it’s stored
Execute this command to generate the class map (and make it part of your deployment process too):
$ composer dump-autoload --optimize --no-dev --classmap-authoritative
--optimizedumps every PSR-0 and PSR-4 compatible class used in your application;
--no-devexcludes the classes that are only needed in the development environment (e.g. tests);
--classmap-authoritativeprevents Composer from scanning the file system for classes that are not found in the class map.
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