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iisiis-7sitecore

HTTP Error 503.2 - Service Unavailable. The serverRuntime@appConcurrentRequestLimit setting is being exceeded

I have a intranet SiteCore website set up on IIS 7 which randomly throws the following error message

    HTTP Error 503.2 - Service Unavailable
    The serverRuntime@appConcurrentRequestLimit setting is being exceeded.

To fix this issue, I have made following changes

  • Increased the Queue Length of application pool myrjetAppPool from 1000 to 65535.
  • Modified Machine.Config to increase requestQueueLimit property of ProcessModel element to 100000

  • Increased appConcurrentRequestLimit to 10000 by running 

    C:\Windows\System32\inetsrv\appcmd.exe set config /section:serverRuntime /appConcurrentRequestLimit:100000

But I'm still getting the same error. ANy help is greatly appreaciated.

Solution

  • Investigate references in the linked url to 'MaxConcurrentReqeustsPerCPU' which you may need to set by creating a new registry key, depending on your OS and framework.

    https://learn.microsoft.com/en-us/archive/blogs/tmarq/asp-net-thread-usage-on-iis-7-5-iis-7-0-and-iis-6-0

    As already commented - check the actual concurrent request count using performance counters to determine which limit you're hitting i.e. it could be a limit of 5000 or maybe 12 (per cpu).

    Edit: I realise this may look like I'm talking about a different setting entirely, but I believe there is overlap here.