AJAX requests hang when streaming file from same domain, different handler

Question

From some page I launch a GET request to some ASHX handler that streams a file to the client. Browser download dialog opens, download works fine.

The problem arises when I want to continue to interact with the page. Interacting launches AJAX requests to some (different) handler to fill the page with content. But, as long as the download is still running, no request will come back from the server.

Not before the download has finished will the requests return and allow interaction with the page.

I have this problem on a debugging IIS 7 server and a production IIS 6 server. The application is ASP.NET on .NET 3.5.

Can anyone tell me what is going on?

Answer 1

ASP.NET serializes all requests that access the same session object for writing.

See this post http://stackoverflow.com/questions/1313765/session-lock-contention-with-page-readonly-in-inproc-mode for some more information. There is another one but I can't find it.