Although using Mechanical scripting APIs on a background thread might work in practice, the APIs are generally not thread-safe, and race conditions might and often do occur when trying to access them from a background thread.

It is still possible to only run parts of your code—namely those parts that do not use these APIs and hence do not risk race conditions—on a background thread. To do so, you can offload work to a new thread. A convenient way to do this is by using the InvokeBackground method exposed on ExtAPI.Application. This method can only take a function without any arguments, but the following technique can be used to pass in arguments to that function:

#function that is to be run in the background. It is safe because it does not using any of the Mechanical scripting APIs

def gradient(vectors)
    print("Computing gradients of the vectors”)

#function that is run on the main thread
def my_script(result):
    vectors = some_function(result)
    def invokeInBackground():
        gradient(vectors)
    ExtAPI.Application.InvokeBackground(invokeInBackground)