PHP: session isn't saving before header redirect

Question

I have read through the php manual for this problem and it seems quite a common issue but i have yet to find a solution. I am saving sessions in a database. My code is as f

Answer 1

Another option than killing your script forcefully with exit is to use session_write_close to force the changes to be written to the session store.

This should however not happen if your script is terminating correctly.

As the documentation about session_write_close states:

End the current session and store session data.

Session data is usually stored after your script terminated without the need to call session_write_close(), but as session data is locked to prevent concurrent writes only one script may operate on a session at any time. When using framesets together with sessions you will experience the frames loading one by one due to this locking. You can reduce the time needed to load all the frames by ending the session as soon as all changes to session variables are done.

In my case this only happened during debugging with Xdebug, when I triggered the same script multiple times and thus multiple process tried to manipulate the same session. Somehow the session could then no longer be unlocked.