AJAX requests hang when served in quick succession

Question

Hello all.

On my laptop I have an app that makes 7 AJAX GET requests to a single PHP script at about the same time (millisecond difference). They all return successfully with the result I want.

Then I moved this script to a server (Windows Server) running Apache and PHP. However, this process hangs when I make the same 7 AJAX requests. However, if I make each request individually then they all come back successful! Something doesn't want me to do all 7.

Why is this happening? What configuration variables in the PHP.ini and httpd.conf can I look for to determine what this is?

Thanks

Answer 1

The server may have a throttler in place to keep excessive requests from coming in too quickly.

Answer 2

Maybe your Apache configuration limits the number of concurrent connections from the same IP, or even Windows. What version of Windows is it? What kind of Apache installation, Standalone or as a part of XAMPP?

Answer 3

I think the problem might be on the browser-side.

Most browsers have a 2 concurrent connections limit when talking to the same server.

When you moved your application to the server, the extra latency might have overlapped your AJAX requests, which on localhost were being served in quick succession.

You may want to check out these related articles:

• The Dreaded 2 Connection Limit
• The Two HTTP Connection Limit Issue
• Circumventing browser connection limits for fun and profit