Ajax requests are served by a single server thread?

I made a simple ajax framework at http://www.iqp.vn and I allow users to make many ajax requests or cancel them.

But from testing I see that, when user make an ajax request that do some thing that takes up a long time like copying/开发者_如何学Cwritting a large text file, subsequent requests will wait until the first one is done before them are executed. On the client I see that the second request although it performes very quick processing always return after the 1st "big" request is done.

I also use hidden form (iframe) submission to allow user to upload files in ajax style, and when user upload a large file, and cancel the request (== reset the iframe on the client), and click to generate another request, I see that the later request always wait for the first upload request to finish.

Can any one help me with this please, I thought using ajax, and (if possible) with multithreaded processing on server, I can get some very nice effects on client.

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Ajax requests are treated like normal requests. You should check:

• Is a ajax call waiting for the other to finish before calling (client side)?
• Do you implement any locking mechanism on the server?
• May be all the threads in the thread pool are busy with other requests

Just for reference, this jQuery plugin can upload many files simultaneously: http://aquantum-demo.appspot.com/file-upload

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This behaviour will depend on the configuration of your web server. If you've only got one thread assigned to the application pool then that thread will be servicing every request.