mmap — Memory-mapped file support

Memory-mapped file objects behave like both bytearray and like file objects. You can use mmap objects in most places where bytearray are expected; for example, you can use the re module to search through a memory-mapped file. You can also change a single byte by doing obj[index] = 97, or change a subsequence by assigning to a slice: obj[i1:i2] = b'...'. You can also read and write data starting at the current file position, and seek() through the file to different positions.

signal — Set handlers for asynchronous events

This module provides mechanisms to use signal handlers in Python.

asynchat — Asynchronous socket command/response handler

Source code: Lib/asynchat.py

asyncore — Asynchronous socket handler

Source code: Lib/asyncore.py

ssl — TLS/SSL wrapper for socket objects

Source code: Lib/ssl.py

socket — Low-level networking interface

Source code: Lib/socket.py