Chapter 3. Controlling CLR Startup and Shutdown

A number of configurable settings determine the basic characteristics of the CLR that gets loaded into the process. For example, various settings enable you to select the version of the CLR to load, configure the basic operations of the garbage collector, and so on. All these settings must be specified before the CLR is loaded.

If you're writing a CLR host, you can have full control over all the settings that control CLR startup. It's worth noting that you might not have to write the host yourself to configure the startup options that your scenario requires. Most hosts provide some mechanism to enable application developers or administrators to customize at least some of the CLR startup options. For example, the default CLR host offers a high degree of customization through application configuration files. The options available when using the default host are described in Chapter 4.

In this chapter, I concentrate on what you do to customize CLR startup when writing your own host. Writing your own host enables you to set all of the startup options and offers you flexibility to control when the CLR is actually loaded into the process.

I start by describing the details of the CLR startup settings, and then I describe how to use the unmanaged function CorBindToRuntimeEx to set them explicitly. When you're talking about controlling CLR startup, it's natural to also talk about controlling CLR shutdown. Although you can't completely unload the CLR from a process and reload it later, the CLR hosting API essentially enables you to disable the CLR. I end the chapter with a discussion of exactly what it means to disable the CLR and how to do it.