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DavidAreen

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IIS Hangs

Between 12:15 and 12:30 PM, usually every day, IIS hangs and it requires a restart. It doesn't happen everyday, there us probably about a 70% probablity of it happening. It's as if there is a scheduled task that is running that is causing this but we have looked at all applications and tasks and there is nothing that is being executed at this time.

We are running asp applications on SQL server and an ODBC connection to an Ingres database. There are no scheduled tasks occuring on the databases.

Does anyone know of anything that could be causing this? What is the best software to get so I can diagnose it? If I can't find the problem then I want to automatically restart iis when it happens - what is te best software to do this?
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meverest
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Hi,

do you restart just IIS (which service?) or the entire web server?

when the web site 'hangs', can you access non-script content (like a plain image or static html files)?

when the site hangs, take a look at the task manager (ctrl-alt-del task manager) processes list - are there any processes using large amount of memory or cpu resource?

Cheers.
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DavidAreen

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Thanks for response. I haven't been able to get the info until just now.

All it needs is an iisreset to get it going again.

Whilst in a hung state images are displayed.

The process w3wp.exe is consuming all available CPU time.
OK, in that case it is almost certainly a bug in the application.

sometimes there is an infinite loop in the code under certain conditions, and when that happens, CPU hits the roof and the worker process (i.e. w3wp.exe) stops responding to new requests.

If there is only the one application running on that site, you may be able to get an idea of which script is causing trouble by looking at the web log file when the thing has failed and see if there is any script that shows up in the last few requests prior to the problem occurence.

Sadly, it is not a simple job to find the cuplrit, so good luck with it! <:-}

Cheers.
Bug?! We dont have those in our applications!!

Aren't there any tools/programs that can assist in this?

I already checked the web logs and I couldn't spot anything that seemed relevant.

There are script timeouts on all the web sites and they aren't very large. If there was a loop then eventually it would just time out and free up the site. When this has happened at the week end it can be stuck for hours before it gets noticed.


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meverest
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Hi

The link pointed me in the right direction. I installled the Microsoft DebugDiag program which contains a hang analysis tool. That spotted the offending dll which of course was not one of ours!

Thanks for the help