Second request not responding at all until the first request complete

Why the second request not responding at all until the first request(using ajax) complete

you need to provide us more information. Comment your code or something, it’s obvious you must do it.

If I’m not wrong, with your information, I can reply you the following: because you’re doing it wrong and I don’t know how to help you because you didn’t provide more information. The ajax requests are asynchronous, so they will be executing in another “threads” while your main code continues its flow. If you have 2 ajax requests, they will follow the same pattern, so it have no sense that the first request needs the second to be finished.

I hope this helps you, if you need more help, please give more information.

Session file locking?