Question

I am using the singleton pattern in all my PHP class files.

Would it by any chance cause a user’s action on the site to conflict with other user’s action?

For instance, when the application goes live and we have several users on the site at the same time, doing similar things hereby calling the same PHP classes (behind the scene), since singleton prevents multiple instance of a class and returns just a single instance.

e.g. I have a class called Search.php and it is a singleton class. This class handles all search queries from the website. If several users are performing a search on the site at the same time, will their actions conflict with each other since its just a single instance of the Search class that can be created.

Thanks very much for your time.

Answer 1

The short answer is no.

Each page request is handled as a unique instance and the only thing that tie them together for each user is the session cookie. Try to think of PHP as an application which starts when you call a script and dies when the script finishes. It does not maintain any state and is not inherently aware of any other PHP instances.

The singleton pattern is simply a way for you to design a class, where you can call it anywhere in your code (like a global) without having to care about whether it already has been instantiated or not and you want it to persist in memory.