Do not use the CI 4 session library

Today I have the PHP Session with Redis configuration, with fallback, name configuration, etc., all defined in my php.ini file, however in CI4 I cannot use PHP's native session_start() to create my sessions.

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Just out of curiosity, because I use PHP session settings geared for Redis too, what is it with CI4 sessions that doesn't work with PHP sessions using Redis?

I don't use it because of the lock it applies to sessions via Redis.
This is most evident in AJAX requests. At least in CI 3, a page that had about 5 requests took a long time for the page to finish loading all the information, as each page remained locked for 1s. In other words, in total I had 5s loading the data to be able to work.

On a large scale, this generates other problems, such as too many connections in the database
Imagine you open 5 req, each one opens a database connection. They will remain open for an average of 5 seconds for a page/user.

Now you have 10 users, making the same request, there are 50 active requests (10 users x 5 req) in the database that cannot be used by other people.