Number of processes to use for multi-processed experience gathering It is important to know how this multi-process training works so that it can be used correctly when you set this >1: When called with this argument set >1, the process will spawn additional processes running the same command as is currently being run but with the additional command line argument LearningProcessIdx. Once the training starts on these sub-processes, this command line argument will be used to indicate that this subprocess should only be used for gathering experience and should not start a new training process itself. This means that this will generally not work in editor (or PIE) since it will end up spawning Multiple additional editor windows. Instead, this should generally only be used in cooked, builds - and in most cases only when running headless. IMPORTANT: If you are seeding your experience generation process to make it deterministic you should use this LearningProcessIdx command line argument to change the seed of your experience gathering - otherwise each process will end up gathering identical experience!