Python: Essential Reference

20. Threads and Concurrency

This chapter describes library modules and programming strategies for writing concurrent programs in Python. Topics include threads, message passing, multiprocessing, and coroutines. Before covering specific library modules, some basic concepts are first described.

Basic Concepts

A running program is called a process. Each process has its own system state, which includes memory, lists of open files, a program counter that keeps track of the instruction being executed, and a call stack used to hold the local variables of functions. Normally, a process executes statements one after the other in a single sequence of control flow, which is sometimes called the main thread of the process. At any given time, the program ...