Last updated: 5 November 2026. See the update log at the end.

In a normal PHP-FPM request, a memory leak mostly does not exist: PHP frees everything when the request ends. The leaks people actually hit happen in processes that stay alive: queue workers, daemons, long import scripts, and application servers like Laravel Octane. The symptom is always the same. Memory climbs a little with every job or request, then something dies with Allowed memory size exhausted , or the operating system kills the process, hours after the code that caused it ran. This article shows how to confirm that you have a leak, the four causes I would check first (each reproduced and measured), how to find the guilty objects, and how to contain a leak you cannot fix immediately.

If your problem is one request using too much memory in a single go, that is not a leak.…