Python includes sophisticated tools for managing concurrent operations using processes and threads. Even many relatively simple programs can be made to run faster by applying techniques for running parts of the job concurrently using these modules.
subprocess (page 535) provides an API for creating and communicating with secondary processes. It is especially good for running programs that produce or consume text, since the API supports passing data back and forth through the standard input and output channels of the new process.
signal (page 553) module exposes the Unix signal mechanism for sending events to other processes. The signals are processed asynchronously, usually by ...