Most of the times the PHP script timeout is set by default by your hosting company to 30 seconds. This means that after 30 seconds of running, your script is immediately killed, which means that all the actions are not completed successfully (if they take more than 30 seconds).

You may easily increase this limit though (or decrease it, e.g to stop abusive users from running abusive code through a possible PHP exploit). One of the ways is to set the time limit inside the php.ini file, if you have access to it.

Another way is to use the set_time_limit() directive at the beginning of your PHP script. The function accepts one parameter, which is the amount of seconds the script is allowed to run. Note that this directive will have no effect if your PHP’s safe_mode is turned on.

The usage is like this:

If you want to remove the timeout completely (your script will run forever until it’s manually killed through the task manager), you can use set_time_limit(0).