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I've got a Windows Server 2008 running IIS 7 with a number of different website each with there own application pool.

Occasionally each one of these sites will fire up a w3wp.exe process when nobody is viewing the website and use about 50% of the CPU resources.

Does anyone know the reason for this and is there a way to stop this or at least reduce it as it slows down the response times on other websites that are being used.

All the websites are MVC applications running .NET 4 and MVC 2 or 3.


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Having the same issue on Window 2008 R2 with IIS 7.5, w3wp process sitting at 50% CPU usage when nothing going on. – John K Jun 2 '11 at 23:50
Any pattern to the timing of the CPU usage? Could it be app pool recycling plus WarmUp? – Rory Sep 17 '13 at 9:53

I would first verify that the application domainis not restarting. Sometimes this is due to files that are changing.

Add this to your master web.config located at:

C:\WINDOWS\Microsoft.NET\Framework\<version>\CONFIG or

<add name="Application Lifetime Events Default" eventName="Application Lifetime Events"
    provider="EventLogProvider" profile="Default" minInstances="1"
    maxLimit="Infinite" minInterval="00:01:00" custom="" />

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Thanks for your help, none of the files you mentioned have been modified recently. Could there be anything else causing this issue? – lancscoder Apr 21 '11 at 19:27

Consider GC as well. The algorithm behind GC is very mysterious, so GC may run when you might not think that it should.

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