Thread Gating in Active Server Pages

• Microsoft Internet Information Services version 5.0

SUMMARY

One of the new performance features introduced in Microsoft Internet Information Services (IIS) for Windows 2000 is a self-tuning mechanism called Active Server Pages Thread Gating.

ASP now detects when executing requests are blocked by external resources and automatically provides more threads to simultaneously execute additional requests and to continue normal processing. If the CPU becomes overburdened, ASP curtails the number of threads in order to reduce the constant switching that occurs when too many non-blocking requests are executing simultaneously.

The purpose of this article is to explain the various metabase properties associated with this concept.

MORE INFORMATION

The following table lists the various metabase properties associated with ASP Thread Gating. The Web service settings for these properties are applicable to all in-process application nodes, at all levels. Metabase settings at the Web-server level or lower will be ignored for in-process applications. However, settings at the Web-server level or lower will be used if that node is isolated as an out-of-process application.

Important: IIS performs thread gating to dynamically control the number of concurrently executing threads, in response to varying load conditions. The default settings for this property, and the other thread gating properties, are designed to be appropriate for the majority of server configurations and traffic conditions. Changing these properties can lead to significant performance degradation.

Property	Default Value	Description
AspThreadGateEnabled	1	This metabase property indicates whether IIS thread gating is enabled.
AspThreadGateLoadHigh	90	This metabase property specifies the minimum CPU load, as a percentage of the total, at which the CPU is considered under high load conditions. This information is used by IIS to perform thread gating, in an attempt to maintain CPU load between the percentages specified in AspThreadGateLoadLow and AspThreadGateLoadHigh.
AspThreadGateLoadLow	75	This metabase property specifies the maximum CPU load, as a percentage of the total, at which the CPU is still considered under low load conditions. This information is used by IIS to perform thread gating, in an attempt to maintain CPU load between the percentages specified in AspThreadGateLoadLow and AspThreadGateLoadHigh.
AspThreadGateSleepDelay	100	This metabase property specifies how long (in milliseconds) to defer thread requests, before the request is rechecked by the IIS thread gating mechanism.
AspThreadGateSleepMax	50	This metabase property specifies the maximum number of times a specific request can be put to sleep (deferred) while IIS performs thread gating.
AspThreadGateTimeSlice	1000	This metabase property specifies how often (in milliseconds) the thread gating mechanism in IIS checks the CPU load.

Additional query words: iis

Keywords :
Version : winnt:5.0
Platform : winnt
Issue type : kbinfo