DLLHOST.EXE (IWAM_machinename) consistent spikes in Performance Monitor

I'm using IIS 6.0 on Windows 2003 Server.  I have been watching the Task Manager sit right around 0% CPU, then suddenly shoot up to 50% to 60% CPU utilization.  Every time, it is the DLLHOST.EXE with User Name IWAM_machinename that is hitting the CPU and ram.  The ram for that DLLHOST goes from 50MB up to sometimes 300MB.   I could not figure this out, because it didn't matter if there were 0 current connections or 5 current connections.  What I just now realized in watching the Performance Monitor is that each dead period where the CPU is doing nothing lasts *EXACTLY* 30 seconds and then it spikes again.  The spikes seem to last consistently around 45 seconds and then it settles down again, but for exactly 30 seconds before it spikes again. Is there something in IIS that might be happening every 30 seconds that could cause this?

Terry Roller
tkreprAsked:
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moduloCommented:
PAQed with points refunded (500)

modulo
Community Support Moderator
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meverestCommented:
check the web logs to see what requests are happening.

cheers.
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anthonywjones66Commented:
The regularity of it could indicate a web page is automatically refereshing it's content on a 30 second interval.

Like Meverest said the web logs could help identify the page creating the activity.

Anthony.
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tkreprAuthor Commented:
I had been all through the logs and there just wasn't anything there to offer any clues.  Most of the time, the W3SVC log showed absolutely no activity and the HTTPERR log showed nothing.  I did find that IIS does some sort of PING every 30 seconds, but I just can't imagine that being the culprit.  I have temporarily given up on IIS 6.0 and set up a Win2000 IIS 5.0 system, moved the site over and it seems fine now.
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tkreprAuthor Commented:
If no objections, I am requesting that this question be closed as it is no longer an issue.
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meverestCommented:
no objection to PAQ & refund from me.

cheers.
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KenSchaeferCommented:
Is there any reason you need to be running IIS6.0 in IIS5 emulation mode? Otherwise, if you are running in IIS6 Worker Process mode you should not be see any IIS related dllhost.exe processes.

On thing you can do is get a dump of the stacks when dllhost.exe is at 100% using IISState orAdPlus

Cheers
Ken
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tkreprAuthor Commented:
Ken,

Funny you should ask.  I have been forced to run IIS 6.0 in 5.0 compatibility mode because the site has a page or pages that are causing IIS problems.  It is constantly recycling the application pools or something, because my sessions usually last about 10 seconds before the session variables are thrown away even though session timeout is set to 20 minutes.  This does not happen in 5.0 compatibility mode.  Anyway, after almost giving up a couple of days ago, I did go back and get an IISSTATE log of the DLLHOST.EXE when it was fine and compared it to the same DLLHOST.EXE IISSTATE log when it was spiking.  What I noticed gave me a clue where to look.  The system was recovering from an MDAC probem.  The text from IISSTATE was "MDAC Error being handled".  The next line mentioned "possible ASP page executing GLOBAL.ASA".  When I saw that, I knew I had a database-type entry in GLOBAL.ASA that was problematic.  I checked and sure enough I had transposed the CURSORLOCATION number to be 3 (client) instead of 2 (server).  I fixed that and searched the entire site and found a few more the same way, fixed those and the CPU and ram spikes disappeared.  I have not yet switched IIS off of the 5.0 compatibility mode, but I have a feeling that what I found in the code is probably the root of all of my problems with IIS 6.

Terry
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KenSchaeferCommented:
Glad you got it fixed.

Using Named Constants (adUseClient / adUseServer) can help with the mixing up of values :-)
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