Re: OT-ish: possible for asp.net 1.1 on IIS5 to bring server down due to CPU consumption?

Ach--sorry--right.  The *machine* did not go down, it was just IIS.
Reportedly inetinfo.exe was soaking up so much CPU that it was an
exercise in patience to remote connect to it & restart IIS, but the OS
itself did not go down.  So--more than just asp.net, but not the whole
OS.  The machine would not serve static pages even.

Would an asp.net app cause inetinfo.exe to peg the CPU?  I would have
thought it'd be an aspnet_wp.exe process.

Many thanks for the ref to processModel--that looks very useful for
keeping these asp.net apps in their place. ;-)

Thanks!

-Roy

-----Original Message-----
From: Discussion of building .NET applications targeted for the Web
[mailto:[email protected]] On Behalf Of Chris Anderson
Sent: Monday, June 02, 2008 11:42 AM
To: [email protected]
Subject: Re: [DOTNET-WEB] OT-ish: possible for asp.net 1.1 on IIS5 to
bring server down due to CPU consumption?

> I need a quick sanity check on something--we've got a 3rd party
asp.net
> v1.1 app installed on a machine w/IIS v5.  Our admin suspects that
this
> app is what brought the machine down recently.  The IIS "application=20
> protection" setting is "Medium (Pooled)".  The process that pegged the

> cpu shortly before the box stopped responding to web requests was=20
> inetinfo.exe.

Firstly "brought a machine down" and "stopped responding to web
requests" are different things.

Was the server as a whole killed, or was just ASP.NET affected?

If ASP.NET takes a high proportion of CPU, it could be down to a number
of things, including high load, it's stuck in a tight loop, or there are
lots of garbage collections occurring.

The first can possibly be checked using the IIS logs.
The second can be difficult to find unless you know the exact
circumstances of the cause, but will be a bug in the app.
The last can be determined using the %Time in GC perf counter and is
difficult to give advice for as there are many causes (mostly
inefficient coding)

Most of the time however you would hit the ASP.NET limits (see the
processModel attributes[1]) and ASP.NET will recycle the process. (So
the site may be unresponsive for a short while, but then will recover as
if nothing happened - although in-memory session state would be lost)

More info would be required to know whether the ASP.NET app caused the
problem, but overall yes, it is possible, although there are mechanisms
in place to recover

Chris

[1] http://msdn.microsoft.com/en-us/library/7w2sway1.aspx

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