How Symfony generates session ID?

Question

I was wondering how Symfony generates session IDs? I was trying to find a snippet reponsible for it but I couldn't. Does it check for colission before returning ID or is it possible (probably nearly impossible but possible) to generate the same session ID for two users?

Answer 1

You can search for classes which implements SessionStorageInterface.

By default native PHP session storage is used, therefore PHP's session_id() is responsible for generating IDs.

Edit: There is another discussion here about how unique is this native session id.