https://github.com/python/asyncio
The #asyncio#module provides infrastructure for writing #single-threaded concurrent code using #coroutines, #multiplexing#I/O access over sockets and other resources, running network clients and servers, and other related primitives. Here is a more detailed list of the package contents:
a pluggable event loop with various system-specific implementations;
transport and protocol abstractions (similar to those in Twisted);
concrete support for TCP, UDP, SSL, subprocess pipes, delayed calls, and others (some may be system-dependent);
a Future class that mimics the one in the concurrent.futures module, but adapted for use with the event loop;
#coroutines and #tasks based on yield from (PEP 380), to help write concurrent code in a sequential fashion;
cancellation support for Futures and coroutines;
synchronization primitives for use between coroutines in a single thread, mimicking those in the #threading module;
an interface for passing work off to a threadpool, for times when you absolutely, positively have to use a library that makes blocking I/O calls.
Note: The implementation of asyncio was previously called "Tulip".