Performance Counters for ASP.NET
ASP.NET supports two groups of performance counters: system and application. System performance counters are exposed in the Windows Performance monitor as the ASP.NET performance counter object. Application performance counters are exposed as the ASP.NET Applications performance object.
 Note |
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The value associated with each performance counter is updated every 400 milliseconds. When creating a monitoring application, be sure to take this time lapse into account so that your code does not use an obsolete counter value. For more information, see Using System Monitoring Components. |
For additional information on system and application performance counters, see How to: Create Performance Counter Categories, Category and Counter Management and How to: Create Custom Performance Counters.
When monitoring the performance of your ASP.NET Web applications, you can track the performance counters listed in the following table.
Performance object | Performance counter |
|---|---|
ASP.NET | Application Restarts |
ASP.NET | Requests Queued |
ASP.NET | Worker Process Restarts |
ASP.NET Applications | Errors Total |
ASP.NET Applications | Requests/Sec |
Processor | % CPU Utilization NoteLow CPU utilization or the inability to maximize CPU utilization regardless of client load can signify contention for a lock or a resource in your Web application. |
In addition, the following performance counters can be valuable in determining problems with your Web applications' performance.
Performance object | Performance counter |
|---|---|
ASP.NET Applications | Pipeline Instance Count |
.NET CLR Exceptions | # of Exceps Thrown |
System | Context Switches/sec |
The # of Exceps Thrown counter displays the number of exceptions thrown in an application, because these can have performance implications. However, some code paths rely on exceptions for proper functioning. For example, the Redirect method on the Response object throws the ThreadAbortException exception, which cannot be caught. Therefore, it can be useful to track this value along with the Errors Total counter to see if the exception generated an error on the application.
The Context Switches/sec counter measures the rate at which thread contexts are switched by all CPUs in the Web server computer. A high number for this counter usually indicates either high contention in locks or many switches by the thread between user and kernel modes. If you experience this, you should investigate further with sampling profilers and other tools.
ASP.NET supports the ASP.NET system performance counters listed in the following table. These counters aggregate information from all ASP.NET applications on a Web server computer.
| Note |
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There is a significant difference between the State Server Sessions counters found in the ASP.NET performance object, which apply only to the server computer on which the state server is running, and the Sessions counters found in the ASP.NET Applications performance object, which apply only to user sessions that occur in-process. |
- Application Restarts
The number of times that an application has been restarted during the Web server's lifetime. Application restarts are incremented each time an Application_OnEnd event is raised. An application restart can occur because of changes to the Web.config file, changes to assemblies stored in the application's Bin directory, or when an application must be recompiled due to numerous changes in ASP.NET Web pages. Unexpected increases in this counter can mean that problems are causing your Web application to recycle. In such circumstances you should investigate as soon as possible.
NoteThis value is reset to zero every time the Internet Information Services (IIS) host is restarted.
- Application Running
The number of applications running concurrently on the server computer.
- Requests Disconnected
The number of requests that have been disconnected due to a communication failure.
- Requests Queued
The number of requests waiting for service from the queue. When this number starts to increment linearly with increased client load, the Web server computer has reached the limit of concurrent requests that it can process. The default maximum for this counter is 5,000. You can change this setting in the Machine.config file.
- Requests Rejected
The total number of requests not executed because of insufficient server resources to process them. This counter represents the number of requests that return a 503 HTTP status code, indicating that the server is too busy.
- Request Wait Time
The number of milliseconds that the most recent request waited in the queue for processing.
- Session State Server Connections Total
The total number of session-state connections made to the computer on which out-of-process session-state data is stored. For more information, see Session-State Modes.
- Session SQL Server Connections Total
The total number of session-state connections made to the Microsoft SQL Server database in which session-state data is stored. For more information, see Session-State Modes.
- 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. This counter is available only on the computer where the state server service (aspnet_state) is running.
- State Server Sessions Active
The number of currently active user sessions. This counter is available only on the computer where the state server service (aspnet_state) is running.
- State Server Sessions Timed Out
The number of user sessions that have become inactive through user inaction. This counter is available only on the computer where the state server service (aspnet_state) is running.
- State Server Sessions Total
The number of sessions created during the lifetime of the process. This counter is the total value of State Server Sessions Active, State Server Sessions Abandoned, and State Server Sessions Timed Out. This counter is available only on the computer where the state server service (aspnet_state) is running.
- Worker Process Restarts
The number of times a worker process has been restarted on the server computer. A worker process can be restarted if it fails unexpectedly or when it is intentionally recycled. If this counter increases unexpectedly, you should investigate as soon as possible.
- Worker Process Running
The number of worker processes running on the server computer.
ASP.NET supports the application performance counters listed in the following table. These counters enable you to monitor the performance of a single instance of an ASP.NET application. A unique instance named __Total__ is available for these counters. This instance aggregates counters for all applications on a Web server (similar to the global counters described earlier in this topic). The __Total__ instance is always available. The counters will display zero when no applications are currently executing on the server.
