Experienced SharePoint administrators would know that over worked servers would drop requests randomly when it can’t handle the load. Sounds familiar?
You could now configure thresholds in SharePoint 2010 and every 5 seconds teach server checks various aspects of its performance such as available Server CPU, Memory, Request Wait Time and ASP.NET request queues.
After 3 unsuccessful checks, the server enters a throttling period and will remain in this state until a successful check is completed.
The following occurs during the HTTP Throttling period:
- No new timer jobs will be started. Requests that were generated before the throttling mode will be completed.
- The server will still continue to accept connections from existing sessions. This will, in theory, keep users from losing any current work when the server begins to throttle requests.
- Any new HTTP GET and Search Robot requests will generate a 503 (Server busy) error message and will be logged in the event viewer.
- The server continues to check itself every 5 seconds and stays throttled until the metrics fall back into the acceptable ranges.
Configuration:
Throttling can be configured per Web application and is enabled through the Central Administration user interface or through a Windows PowerShell™ command.
To configure via Central Administration:
- In SharePoint 2010 Central Administration, select Application Management -> Manage web applications.
- Select the web application you want to configure
- Click General Settings on the Ribbon
- Select Resource Throttling
- Select On or HTTP Request
After throttling is enabled, the Windows PowerShell commands can be used to view and adjust the throttling thresholds:
GetSPWebApplicationHttpThrottlingMonitor
SetSPWebApplicationHttpThrottlingMonitor
The image from TechNet (below) is an example of the GetSPWebApplicationHttpThrottlingMonitor Windows PowerShell command.
