asyncio — Asynchronous I/O

Hello World!

import asyncio

async def main():
    print('Hello ...')
    await asyncio.sleep(1)
    print('... World!')

# Python 3.7+
asyncio.run(main())

asyncio is a library to write concurrent code using the async/await syntax.

asyncio is used as a foundation for multiple Python asynchronous frameworks that provide high-performance network and web-servers, database connection libraries, distributed task queues, etc.

asyncio is often a perfect fit for IO-bound and high-level structured network code.

asyncio provides a set of high-level APIs to:

run Python coroutines concurrently and have full control over their execution;
perform network IO and IPC;
control subprocesses;
distribute tasks via queues;
synchronize concurrent code;

Additionally, there are low-level APIs for library and framework developers to:

create and manage event loops, which provide asynchronous APIs for networking, running subprocesses, handling OS signals, etc;
implement efficient protocols using transports;
bridge callback-based libraries and code with async/await syntax.

Reference

High-level APIs

Low-level APIs

Guides and Tutorials

Note

The source code for asyncio can be found in :source:`Lib/asyncio/`.

asyncio — Asynchronous I/O — Python documentation

asyncio — Asynchronous I/O