Classes and runspace affinity

Classes in PowerShell have affinity with the runspace the instance of a class was created within. This means that any method call made in a different runspace is queued to run in the original runspace.

This affinity can be shown by inspecting the runspace ID. In a script executed within a newly created PowerShell runspace, each ID will be different:

1..5 | ForEach-Object {
    [PowerShell]::Create().
        AddScript('[Runspace]::DefaultRunspace.Id').
        Invoke()
}

The command above will show the individual runspace IDs like those shown below:

2
3
4
5
6

In the example below, a class is defined, then an instance is created. The instance of the class is passed as an argument to a newly created runspace to execute the method. Each execution of the Run method will show the value 1 if the class instance is created in the interactive runspace:

class WithAffinity {
    [void] Run() {
        [Console]::WriteLine([Runspace...