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ASP.NET supports two groups of performance counters: system and application. The former is exposed in PerfMon under the ASP.NET System performance counter object, while the latter is exposed ASP.NET Applications performance object.

ASP.NET supports the following global performance counters, which either aggregate information for all ASP.NET applications on a Web server computer or apply generally to the ASP.NET subsystem, which can include Web farms and Web gardens.

Application Restarts

The number of times that an application has been restarted during the Web server’s lifetime. Application restarts is incremented with each Application_End event.

NOTE: This value will be reset every time the Internet Information Services ( IIS ) host is restarted.

Application Running

The number of applications running on the server computer.

Requests Disconnected

The number of requests that were disconnected due to a communication failure.

Requests Queued

The number of requests waiting for service from the queue.

Request Wait Time

The number of milliseconds that the most recent request waited for processing in the queue.

State Server Sessions Abandoned

The number of user sessions that have been explicitly abandoned. These are sessions that are ended by specific user actions, such as closing the browser or navigating to another site.

State Server Sessions Active

The number of currently active user sessions.

State Server Sessions Timed Out

The number of user sessions that have become inactive through user inaction.

State Server Sessions Total

The number of sessions created during the lifetime of the process. This counter is the cumulative value of State Server Sessions Active, State Server Sessions Abandoned, and State Server Sessions Timed Out.

Worker Process Restarts

The number of times a worker process has been restarted on the server computer.

Worker Process Running

The number of worker processes running on the server computer.

ASP.NET supports the following application performance counters, which you can use to monitor the performance of a single instance of an ASP.NET application. A unique instance appears for these counters, named __Total__, which aggregates counters for all applications on a Web server ( similar to the global counters above ). The __Total__ instance is always available — the counters will display zero when no applications are present on the server.

Anonymous Requests

The number of requests utilizing anonymous authentication.

Anonymous Requests/Sec

The number of request per second utilizing anonymous authentication.

Cache Total Entries

The total number of entries within the cache. This counter includes both internal use of the cache by the ASP.NET framework and external use of the cache through exposed APIs.

Cache Total Hits

The total number of hits from the cache. This counter includes both internal use of the cache by the ASP.NET framework and external use of the cache through exposed APIs.

Cache Total Misses

The number of failed cache requests per application. This counter includes both internal use of the cache by ASP.NET and external use of the cache through exposed APIs.

Cache Total Hit Ratio

The ratio of hits to misses for the cache. This counter includes both internal use of the cache by ASP.NET and external use of the cache through exposed APIs.

Cache Total Turnover Rate

The number of additions and removals to the total cache per second. It is useful in helping determine how effectively the cache is being used. If the turnover is large, then the cache is not being used efficiently.

Cache API Entries

The total number of entries in the application cache.

Cache API Hits

The total number of hits from the cache when accessed only through the external Cache APIs. This counter does not track any use of the cache internally by ASP.NET.

Cache API Misses

The total number of failed requests to the cache when accessed through the external Cache APIs. This counter does not track any use of the cache internally by ASP.NET.

Cache API Hit Ratio

The cache hit to miss ratio when accessed through the external Cache APIs. This counter does not track any use of the cache internally by ASP.NET.

Cache API Turnover Rate

The number of additions and removals to the cache per second, when used via the external APIs ( excluding internal use by the ASP.NET framework ). It is useful in helping determine how effectively the cache is being used. If the turnover is large, then the cache is not being used effectively.

Compilations Total

The total number of compilations that have taken place during the lifetime of the current Web server process. This occurs when a file with an .aspx, .asmx, .ascx, or .ashx extension or code-behind source files are dynamically compiled on the server.

NOTE: This number will initially climb to some peak value as requests are made to all parts of an application. Once a compilation occurs, however, the resulting binary is saved to disk where it will be re-used until its source file changes. This means that even in the event of a process restart the counter can remain at zero ( inactive ) until the application is modified or re-deployed.

Debugging Requests

The number of requests that occurred while debugging was enabled.

Errors During Preprocessing

The number of errors that occurred during parsing. Excludes compilation and runtime errors.

Errors During Compilation

The number of errors that occurred during dynamic compilation. Excludes parser and runtime errors.

Errors During Execution

The total number of errors that occurred during the execution of an HTTP request. Excludes parser and compilation errors.

Errors Unhandled During Execution

The total number of unhandled errors that occurred during the execution of HTTP requests.

NOTE: An unhandled error is any uncaught runtime exception that escapes user code on the page and enters the ASP.NET internal error-handling logic. Exceptions to this rule occur when:

• Custom errors are enabled, an error page is defined, or both.
• The Page_Error event is defined in user code and the error is either cleared ( using the HttpServerUtility.ClearError Method method ) or a redirect is performed.

Errors Unhandled During Execution/Sec

The number of unhandled exceptions per second that occur during the execution of HTTP requests.

Errors Total

The total number of errors that occured during the execution of HTTP requests. Includes any parser, compilation, or runtime error. This counter is the sum of the Errors During Compilation, Preprocessing, and Request Execution counters.

Errors Total/Sec

The number of errors per second that occur during the execution of HTTP requests. Includes any parser, compilation, or runtime error.

Output Cache Entries

The total number of entries in the output cache.

Output Cache Hits

The total number of requests serviced from the output cache.

Output Cache Misses

The number of failed output cache requests per application.

Output Cache Hit Ratio

The percentage of total requests serviced from the output cache.

Output Cache Turnover Rate

The number of additions and removals to the output cache per second. It is useful in helping determine how effectively the cache is being used. If the turnover is large, then the cache is not being used effectively.

Pipeline Instance Count

The number of active pipeline instances.

Request Bytes In Total

The total size, in bytes, of all requests.

Request Bytes Out Total

The total size, in bytes, of responses sent to a client. This does not include standard HTTP response headers.

Requests Executing

The number of requests currently executing.

Requests Failed

The total number of failed requests, including requests that timed out, requests that were not authorized ( 401 ), or requests not found ( 404 or 414 ). Note: the equivalent ASP counter would also increment on requests rejected, which we cannot do ( because the rejection is done by IIS and not our process model ).

Requests Not Found

The number of requests that failed because resources were not found ( status code 404, 414 ).

Requests Not Authorized

The number of requests that failed due to no authorization ( status code 401 ).

Requests Succeeded

The number of requests that executed successfully ( status code 200 ).

Requests Timed Out

The number of requests that timed out.

Requests Total

The total number of requests since the service was started.

Requests/Sec

The number of requests executed per second.

Sessions Active

The current number of sessions currently active.

Sessions Abandoned

The number of sessions that have been explicitly abandoned.

Sessions Timed Out

The number of sessions that timed out.

Sessions Total

The number of sessions timed out.

Transactions Aborted

The number of transactions aborted.

Transactions Committed

The number of transactions committed.

Transactions Pending

The number of transactions in progress.

Transactions Total

The total number of transactions since the service was started.

Transactions/Sec

The number of transactions started per second.

Monitoring ASP.NET Application Performance