Sessions Performance Issue (php7.1, CI 3.1.5)

This solved my problems - wish this would be documented better with CI: https://ma.ttias.be/php-session-locking-...-requests/

https://www.codeigniter.com/user_guide/l...oncurrency

A note about concurrency
Unless you’re developing a website with heavy AJAX usage, you can skip this section. If you are, however, and if you’re experiencing performance issues, then this note is exactly what you’re looking for.

Sessions in previous versions of CodeIgniter didn’t implement locking, which meant that two HTTP requests using the same session could run exactly at the same time. To use a more appropriate technical term - requests were non-blocking.

However, non-blocking requests in the context of sessions also means unsafe, because modifications to session data (or session ID regeneration) in one request can interfere with the execution of a second, concurrent request. This detail was at the root of many issues and the main reason why CodeIgniter 3.0 has a completely re-written Session library.

Why are we telling you this? Because it is likely that after trying to find the reason for your performance issues, you may conclude that locking is the issue and therefore look into how to remove the locks ...

DO NOT DO THAT! Removing locks would be wrong and it will cause you more problems!

Locking is not the issue, it is a solution. Your issue is that you still have the session open, while you’ve already processed it and therefore no longer need it. So, what you need is to close the session for the current request after you no longer need it.

Long story short - call session_write_close() once you no longer need anything to do with session variables.