CentOs + nginx + php-fpm + MySQL - how to allow multiple parallel requests from one client?

Question

PHP

I have absolutely no idea what the cause of the problem is, so I will describe the situation in general.
Bundle of nginx + php-fpm + MySQL on CentOs. If you run a long script in one browser tab, the site will not open in the next tab (waiting for a response) until the script in the first tab is executed.
If you open an incognito tab, the site will open.
Of course, the same story with ajax requests - until one works, the other does not respond.
I would like to know what this behavior generally depends on and whether it can be changed so that the requests do not affect each other and are executed in parallel.

Answer 1

Sessions.
Or at the very beginning of the script, close the session us3.php.net/manual/ru/function.session-destroy.php
Or try to store the session in memcached
In any case, there will be a data storage problem. If the second script writes something to the session, and at the end of the first there is also a record, then the data from the second will be overwritten.