Impove App Launch Performance With MultiCore JIT in .NET Framework

The feature works by the JIT compiling the methods likely to be executed based on profiles created during previous compilations, which will run on a separate processor core taking care of the JIT Compilation while the main execution thread runs on a different core.

In the ideal case, the second core quickly gets ahead of the mainline execution of the application, so whenever a method is required it is already compiled. As a result, the main thread doesn't need to do as much compilation, and your application launches faster.

In order to know which methods to compile, the feature generates profile data in the Recording mode that keeps track of the methods that are executed. Then the next time the application runs the call will look for that profile and when it finds it it plays back; that means it starts compiling all the methods that were saved for that profile.

Note. MultiCore JIT requires a multicore machine to take advantage of its algorithms otherwise the CLR will ignore it on single-core machines.

How to enable Multicore JIT in a .NET 4.5 application?

You can use this feature of the runtime to significantly improve the startup times of both client applications and Websites in .NET framework 4.5.

Since ASP.NET applications run in a hosted environment, this feature is turned on for these applications automatically. Therefore JIT compiling using multiple cores is enabled by default in ASP.NET 4.5 and Silverlight 5.

But, if you want to disable this feature in your ASP.NET 4.5 applications then write the following code on the web. config file.

<system.web>
  <compilation profileGuidedOptimizations="None" />
</system.web>

But in a Windows-based application, you will need to enable the Multicore JIT feature explicitly.

Let's see how.

It is simple to use Multicore JIT, there is a class in the .NET Framework named "System.Runtime.ProfileOptimization" that you can use to start profiling at the entry point of your application.

Optimization Profilers

The ProfileOptimization is a new type introduced in .Net 4.5 to improve the startup performance of application domains in applications that require the just-in-time (JIT) compiler by performing background compilation of methods that are likely to be executed, based on profiles created during previous compilations.

See the MSDN documentation for more information.

https://learn.microsoft.com/en-us/docs/

The two methods that you can call at the entry point of your application.

1. SetProfileRoot: This method is used to specify the root path, where to save the JIT profile compiled information for optimization.
2. StartProfile: This method is used to start the Multicore just-in-time compilation.

You must write the following code in your application constructor in order to enable Multicore JIT.

public App()
{
    ProfileOptimization.SetProfileRoot(@"C:\MyAppFolder");
    ProfileOptimization.StartProfile("Startup.Profile");
}

Now that's all to enable the Multicore feature in your application; the rest of the work will be handled by the CLR automatically.

Conclusion

This is definitely a great feature for improving application launch performance. Applications now start 50% faster than before. If you are developing a web application, you will not need to do something and if you are developing a Desktop application then you can turn on this amazing feature with only a few lines of code.