Symfony 4.4 overhead with opcache.preload

Problem

When using Symfony 4.4, you are experiencing large performance impacts when opcache.preload is active.

Solution

1. In your newrelic.ini file, set newrelic.preload_framework_library_detection = false.

2. Ensure that your preload settings are compliant with Symfony.

   Tip

   If you're using PHP 7.4, see:

   • Symfony's PHP 7.4 preload documentation
   • Preloading Symfony Applications in PHP 7.4

3. Restart your service.

Cause

When newrelic.preload_framework_library_detection and opcache.preload are both enabled, we query the opcache status with each function call. However, there are several issues related to using Symfony 4.4 that can result in this query returning null. This consistently happening will cause significant overhead in New Relic's PHP agent.

Currently, this issue has only been reported by environments using Kubernetes.