session_start hangs

There are many reasons for that, here are a few of them:

A. The session file could be opened exclusively. When the file lock is not released properly for whatever reason, it is causing session_start() to hang infinitely on any future script executions. Workaround: use session_set_save_handler() and make sure the write function uses fopen($file, 'w') instead of fopen($file, 'x')

B. Never use the following in your php.ini file (entropie file to "/dev/random"), this will cause your session_start() to hang:

<?php
ini_set("session.entropy_file", "/dev/random");
ini_set("session.entropy_length", "512");
?>

C. session_start() needs a directory to write to.

You can get Apache plus PHP running in a normal user account. Apache will then of course have to listen to an other port than 80 (for instance, 8080).

Be sure to do the following things: - create a temporary directory PREFIX/tmp - put php.ini in PREFIX/lib - edit php.ini and set session.save_path to the directory you just created

Otherwise, your scripts will seem to 'hang' on session_start().

If this helps:

In my scenario, session_start() was hanging at the same time I was using the XDebug debugger within PHPStorm, the IDE, on Windows. I found that there was a clear cause: Whenever I killed the debug session from within PHPStorm, the next time I tried to run a debug session, session_start() would hang.

The solution, if this is your scenario, is to make sure to restart Apache every time you kill an XDebug session within your IDE.

I had a weird issue with this myself.

I am using CentOS 5.5x64, PHP 5.2.10-1. A clean ANSI file in the root with nothing other than session_start() was hanging. The session was being written to disk and no errors were being thrown. It just hung.

I tried everything suggested by Thariama, and checked PHP compile settings etc.

My Fix:

yum reinstall php;  /etc/init.d/httpd restart

Hope this helps someone.

To everyone complaining about the 30 seconds of downtime being unacceptable, this was an inexplicable issue on a brand new, clean OS install, NOT a running production machine. This solution should NOT be used in a production environment.