Run control and candidate in parallel or candidate async

When setting up an experiment, we often want to ensure that the user isn't adversely affected. In order to avoid possible slow downs in the candidate code from affecting the user, would it be possible to run the control and the candidate in parallel? Or better yet, run the candidate completely asynchronously?

I have spent a lot of time writing JavaScript recently so please forgive my lack of ideas on how to solve this problem in Python. Thanks for porting this to Python by the way!

Start by tracing how an experiment currently runs its control and candidate code, then identify the execution entry points and any existing tests for experiment setup or result collection. Define whether parallel or asynchronous candidate execution is required and how completion, errors, and user impact should be measured before implementation.

Written by the indexing model from the issue text.