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How to: Instrument a Dynamically Compiled ASP.NET Web Application and Collect Memory Data by Using the Profiler Command Line

This topic describes how to use Visual Studio Profiling Tools command-line tools to collect detailed .NET memory allocation and object lifetime data for a dynamically compiled ASP.NET Web application by using the instrumentation profiling method.

Note Note

Command-line tools of the Profiling Tools are located in the \Team Tools\Performance Tools subdirectory of the Visual Studio installation directory. On 64 bit computers, both 64 bit and 32 bit versions of the tools are available. To use the profiler command-line tools, you must add the tools path to the PATH environment variable of the command prompt window or add it to to the command itself. For more information, see Specifying the Path to Profiling Tools Command Line Tools.

To collect performance data from a ASP.NET Web application, you modify the web.config file of the target application to enable the VSInstr.exe tool to instrument the dynamically compiled application files. You then use the VSPerfCLREnv.cmd tool to configure the server that hosts the ASP.NET Web application and enable .NET memory profiling by setting the appropriate environment variables, and then restart the computer.

To collect data, start the profiler and then run the target application. While the profiler is attached to the application, you can pause and resume data collection.When you have collected the appropriate data, close the application, close the Internet Information Services (IIS) worker process, and then shut down the profiler.

When you have completed your profiling work, restore the web.config file and the Web server to their original states.

To configure the ASP.NET Web application and the Web server

  1. Modify the web.config file of the target application. See How to: Modify Web.Config Files to Instrument and Profile Dynamically Compiled ASP.NET Web Applications.

  2. Open a command prompt window on the computer that hosts the Web application.

  3. Initialize the profiling environment variables. Type:

    VSPerfClrEnv /globaltracegc


    VSPerfClrEnv /globaltracegclife

    • /globaltracegc enables the collection of memory allocation data.

    • /globaltracegclife enables the collection of memory allocation data and object lifetime data.

  4. Restart the computer.

To profile the ASP.NET Web application

  1. Start the profiler. Type:

    VSPerfCmd /start:trace /output:OutputFile [Options]

    • The /start:trace option initializes the profiler.

    • The /output:OutputFile option is required with /start. OutputFile specifies the name and location of the profiling data (.vsp) file.

    You can use any of the following options with the /start:trace option.

    Note Note

    The /user and /crosssession options are usually required for ASP.NET applications.



    /user :[Domain\]UserName

    Specifies the optional domain and user name of the account that owns the ASP.NET worker process. This option is required if the process is running as a user other than the logged on user. The name is listed in the User Name column on the Processes tab of Windows Task Manager.


    Enables profiling of processes in other sessions. This option is required if the application is running in a different session. The session id is listed in the Session ID column on the the Processes tab of Windows Task Manager. /CS can be specified as an abbreviation for /crosssession.


    Starts the profiler with data collection paused. Use /globalon to resume profiling.

    /counter : Config

    Collects information from the processor performance counter specified in Config. Counter information is added to the data collected at each profiling event.

    /wincounter : WinCounterPath

    Specifies a Windows performance counter to be collected during profiling.

    /automark : Interval

    Use with /wincounter only. Specifies the number of milliseconds between Windows performance counter collection events. Default is 500 ms.

    /events : Config

    Specifies an Event Tracing for Windows (ETW) event to be collected during profiling. ETW events are collected in a separate (.etl) file.

  2. Start the ASP.NET Web application in the typical way.

While the target application is running, you can control data collection by starting and stopping the writing of data to the profiler data file by using VSPerfCmd.exe options. Controlling data collection enables you to collect data for a specific part of program execution, such as starting or shutting down the application.

To start and stop data collection

  • The following pairs of options start and stop data collection. Specify each option on a separate command line. You can turn data collection on and off multiple times.



    /globalon /globaloff

    Starts (/globalon) or stops (/globaloff) data collection for all processes.

    /processon : PID /processoff:PID

    Starts (/processon) or stops (/processoff) data collection for the process specified by the process ID (PID).

    /threadon : TID /threadoff:TID

    Starts (/threadon) or stops (/threadoff) data collection for the thread specified by the thread ID (TID).

  • You can also use the VSPerfCmd.exe /mark option to insert a profiling mark into the data file. The /mark command adds an identifier, a timestamp, and an optional user-defined text string. Marks can be used to filter the data in profiler reports and data views.

To end a profiling session, close the target ASP.NET Web application, stop Internet Information Services (IIS) to stop the profiled process, and then shut down the profiler. Then restart IIS.

To end a profiling session

  1. Close the ASP.NET Web application.

  2. Close the ASP.NET worker process by resetting Internet Information Services (IIS). Type:

    IISReset /stop

  3. Shut down the profiler. Type:

    VSPerfCmd /shutdown

  4. Restart IIS. Type:

    IISReset /start

When you have completed all profiling, replace the web.config file, clear the profiling environment variables, and restart the computer to restore the server and the ASP.NET application to their original states.

To restore the application and computer configuration

  1. Replace the web.config file with a copy of the original file.

  2. (Optional). Clear the profiling environment variables. Type:

    VSPerfCmd /globaloff

  3. Restart the computer.

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