How can I find out why some classic ASP pages randomly take so long?

Question

I am working on a fairly large classic asp / SQL Server application. A new version was released a few months ago with many new features, and I must have a very nasty bug somewhere: some very simple pages randomly take a very long time to complete.

A few tips:

• This is not a database: when I run the query profiler, it does not detect any long query
• When I run the IIS diagnostic tools, reqviewer shows that the request is in a "processing" state
• This can happen on ANY page.
• I can not reproduce it easily, it is completely random.
• To have an idea of ​​a "very long time": this morning I had a page to execute for more than 5 minutes, when it needs to be returned to the client in less than 100 ms.
• An application can handle quite large file uploads and downloads (up to 2 GB in size). This is also handled by a classic asp script using SoftArtisan FileUp. Do not think that this may cause a problem, although we have had these downloads for quite some time.
• I had a problem on two separate servers (in two different places with different data sets). One of them starts the application with good SQL Server 2000, and the other starts SQL Server 2005. In both cases, the IIS 6 web server.

Any idea what the problem is or how to solve this problem?

Thanks.

Sebastien

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• http://msdn.microsoft.com/en-us/library/aa366750(v=vs.85).aspx
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So, if you try to load the page, and someone else hit this URL at the same time, you will queue for them. It seems that the pages take a lot of time, but this is simply because the server processes page requests in one line of the file, and sometimes you are not at the front of the line.

You may have enabled this for debugging and forgot to disable it for production.