How to optimize Symfony project performance 👨‍💻
Tags: symfony, php, webdev, tutorial
Published: 2023-09-25 07:24:20

Looking for that extra boost in your Symfony projects? 

Symfony framework is ideal for building complex applications. The framework provides various tools and features specifically designed for building scalable and high-performance PHP web applications. However, there's always room for improvement. By optimizing both your servers and applications, you can achieve even better performance.

Let's discover some actionable steps you can take to supercharge your Symfony projects.

## **1. Symfony application checklist**

**Install APCu Polyfill if your server uses APC**

Users who rely on the legacy APC PHP extension, as opposed to OPcache, should prioritize the installation of the [APCu Polyfill](https://github.com/symfony/polyfill-apcu) component. By doing so, they ensure compatibility with APCu PHP functions and gain access to useful Symfony features like the APCu Cache adapter.

**Restrict the number of locales enabled**

Limiting the number of [locales](https://symfony.com/doc/current/components/intl.html#locales) can lead to performance improvements. Enable only the necessary locales to reduce overhead.

## **2. Production server checklist**

**Dump the service container into a single file**

By default, Symfony compiles the service container into multiple files. However, a specific parameter can compile the entire container into one file, boosting performance, especially with "[class preloading](https://symfony.com/blog/php-preloading-and-symfony)" in PHP 7.4 and newer.

**Use the OPcache byte code cache**

OPcache is a powerful tool that stores compiled PHP files, eliminating the need to recompile them for every request. While there are several byte code caches available, OPcache is built into PHP 5.5 and later. For older PHP versions, APC is a popular choice.

**Configure OPcache for maximum performance**

The default OPcache configuration might not be optimal for Symfony applications. Adjusting settings, such as not checking PHP file timestamps in production (since they shouldn't change unless a new version is deployed), can lead to significant performance gains. After each deployment, it's crucial to clear and regenerate the OPcache cache to reflect any updates in the application.

**Optimize composer autoloader**

In development, the class loader is optimized to detect new and changed classes. However, in production, PHP files should remain static unless a new version is deployed. You can optimize Composer's autoloader to scan the entire application once, building an optimized "class map". This map, stored in **'vendor/composer/autoload_classmap.php'**, provides a comprehensive array of class locations, streamlining class loading.

## **3. Profiling Symfony applications**

Profiling is an essential step in understanding the performance bottlenecks of your application. By analyzing the execution of your application, you can pinpoint areas that need optimization. Symfony offers various tools to assist in this endeavor.

**Profiling with Blackfire**

[Blackfire](https://www.blackfire.io/) stands out as a premier tool for profiling and optimizing Symfony applications across development, test, and production stages. While it's a commercial service, Blackfire offers a comprehensive demo that allows developers to experience its full range of features.

**Profiling with Symfony Stopwatch**

[The Stopwatch component](https://symfony.com/doc/5.0/components/stopwatch.html) allows for more granular profiling. When using autowiring, simply type-hint any controller or service argument with the Stopwatch class, and Symfony will inject the **'debug.stopwatch'** service. When invoked during a request, this service will display a new event called **'export-data'** in the Symfony profiler. The **'start()'**, **'stop()'**, and **'getEvent()'** methods of this service provide detailed information about the current event, even while it's still in progress.

## **4. Advanced performance techniques**

Beyond the basics, there are advanced techniques and configurations that can further enhance the performance of your Symfony application. Let's explore some of these.

**Configure the PHP realpath cache**

PHP caches the result when a relative path is transformed into its real and absolute path to boost performance. For applications that open numerous PHP files, like Symfony projects, it's recommended to adjust certain values for optimal results. However, it's essential to note that PHP disables the realpath cache when the **'open_basedir'** config option is enabled.

**Disable dumping the container as XML in debug mode**

In debug mode, Symfony generates an XML file containing all service container information, such as services and arguments. This XML file aids various debugging commands like **'debug:container'** and **'debug:autowiring'**. However, the file size and generation time increase as the container grows. If the benefits of this XML file don't justify the performance decrease, you can disable its generation.

**Leverage class preloading with OPcache**

Starting from PHP 7.4, OPcache can compile and load classes during startup, making them available for all requests until the server restarts. This significantly boosts performance. During container compilation, Symfony generates a file listing classes to preload. Instead of using this file directly, utilize the **'config/preload.php'** file created when using [Symfony Flex](https://symfony.com/components/Symfony%20Flex) in your project. If this file is missing, you can update the Symfony Flex recipe with the command: **'composer recipes:update symfony/framework-bundle'**.

**Optimizing database queries**

While Symfony itself is a robust framework, the performance of your application can also be influenced by how you handle database operations. Ensure your database queries are optimized, utilize caching where appropriate, and consider using a database profiler to identify slow or inefficient queries.

Performance optimization is an ongoing process. As technologies evolve and applications grow, new challenges and opportunities arise. By staying informed and proactive, you can ensure that your Symfony application remains fast, efficient, and ready to handle the demands of the modern web.

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