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I've been working on a VB.NET/VS2008/AJAX/SQL Server project for over 2 years now without any real issues coming up. However, we're in the last week of our project doing some heavy stress testing and the project starts failing once I get about 150 simultaneous users. I've even gone so far as to create a stripped down version of the site which only logs in a user, pulls up their profile and then logs off. That still fails under stress. When I says "fails" I mean the CPU's are spiked and the App Pool eventually crashes. This is running on a Windows 2008 R2 duo quad server w/ 16 gig of memory. The memory never spikes but the CPU tops out.

I ran YSlow on the site and it pointed out that I needed to compress the .axd files, etc... I did that by implementing Gzip compression on everything but that's what got me to the 150 users. I run YSlow now and it says everything is "A".

I'm really not sure where to go from here. I'd be more than willing to share the stripped down version of the site for anyone to review. I'm not sure if it's the server, my code or the web.config.

Joel Coehoorn
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Bee Gates
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  • When you say the CPU is spiking, which server are you referring to? The database server? Or the web server? – Mark J Miller Nov 22 '11 at 16:54
  • Sounds to me like something fishy is going on. This will be difficult to diagnose without the code and/or some event logs that illustrate the application pool crashing – John Culviner Jun 07 '12 at 04:08
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    Please, code would be nice. Are you not closing SQL connections on time? Not performing disposes on objects? Not enough using's? Do you have perhaps some threads in the background? Having a very deep throw stack somewhere? – NeroS Jun 12 '12 at 20:31
  • Is there any failsafe options in your iis to avoid high processor rate via recycling app pool? – kisp Aug 06 '12 at 20:31

1 Answers1

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I know it is a bit late but have you considered increasing the number of worker processes in the application pool of your site to form a web garden? You can do this on the IIS Manager.

honor
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