Is the session destruction mechanism in PHP asynchronous?

Question

According to the default configuration, the session in PHP will enter the destruction process of expired session files after 24 minutes and a probability of 1/1000 is triggered. Will this process be synchronized with the request processing process? Or will an asynchronous process be started? If it is the former, won't it block the execution of this request?

Answer 1

It is not asynchronous and will indeed block the user request, so it needs probability to start.

Answer 2

It’s not asynchronous. Every time PHP accepts a request, there is a certain probability to clean up the expired session. This probability is controlled by these parameters

session.gc_probability = 1
session.gc_pisor = 1000
session.gc_maxlifetime = 1440