What happens to a session when a script gets aborted? I don't believe there can be a one-shot solution for all situations, and I can easily imagine that one would want to keep the session data, but doesn't want to save anything changed _just_now_ (similar to a transaction rollback).

A function session_abort() or session_reset() could do just this - abort any open session without modifying the session storage. Having such methods one could decide in a registered shutdown function how to proceed.

session_abort()
Works similar to session_write_close() except that it doesn't store session data

session_reset()
Rereads the $_SESSION superglobal from stored session data, destroying any modifications so far. The session remains open.

Thanks for consideration (possibly in 4.3?),
Ernest