The CLR (Common Language Runtime) is the execution environment for code written for the .NET Framework. The CLR manages the execution of .NET code, including memory allocation and garbage collection (which helps avoid memory leaks), security (including applying differing trust levels to code from different sources), thread management, enforcing type-safety, and many other tasks.

The CLR works with every language available for the .NET Framework, so there is no need to have a separate runtime for each language. Code developed in a .NET language is compiled by the individual language compiler (such as the Visual Basic .NET compiler) into an intermediate format called Intermediate Language (IL). At runtime, this IL code generated by the compiler is just-in-time (JIT) compiled by the CLR into native code for the processor type the CLR is running on.

This AspNetClrJit test monitors the JIT compilation performed by the CLR. This compilation provides the flexibility of being able to develop with multiple languages and target multiple processor types while still retaining the performance of native code at execution time.

Target of the test : An ASP .Net server

Agent deploying the test : An internal agent

Outputs of the test : One set of results for the ASP .Net server being monitored.

Configurable parameters for the test
Parameter Description

Test Period

How often should the test be executed


The IP address of the host for which this test is to be configured.


The port at which the specified Host listens.

Measurements made by the test
Measurement Description Measurement Unit Interpretation

ASP .Net – Time in JIT

Indicates the percentage of elapsed time spent in JIT compilation; a JIT compilation phase is the phase when a method and its dependencies are being compiled..



ASP .Net – Data JIT rate

Indicates the rate at which IL bytes are jitted.



ASP .Net – JIT failures

Indicates the number of methods the JIT compiler has failed to JIT during the last measurement period.


An unusually high value may indicate a sudden increase in jit failures occured in the application.

ASP .Net – Data jitted

Indicates the total IL bytes jitted during the last measurement period.



ASP .Net – Methods jitted

Indicates the methods compiled Just-In-Time (JIT) by the CLR JIT compiler during the last measurement period.


AppDomains (application domains) provide a secure and versatile unit of processing that the CLR can use to provide isolation between applications running in the same process.