create f n starts n parallel workers waiting for tasks

perform workers tasks f distributes tasks to all workers in parallel, collecting results with f and returns when all tasks are finished

stop ?wait workers kills worker processes with SIGTERM is wait is specified it will wait for at most wait seconds before killing with SIGKILL, otherwise it will wait indefinitely

• parameter autoexit

  determines whether workers will exit once there are no more tasks, it means perform shouldn't be called again for this instance