uvloop is a fast, drop-in replacement of the built-in asyncio event loop. uvloop is implemented in Cython and uses libuv under the hood.

The project documentation can be found here. Please also check out the wiki.

uvloop makes asyncio 2-4x faster.

The above chart shows the performance of an echo server with different message sizes. The sockets benchmark uses loop.sock_recv() and loop.sock_sendall() methods; the streams benchmark uses asyncio high-level streams, created by the asyncio.start_server() function; and the protocol benchmark uses loop.create_server() with a simple echo protocol. Read more about uvloop in a blog post about it.

uvloop requires Python 3.8 or greater and is available on PyPI. Use pip to install it:

$ pip install uvloop

Note that it is highly recommended to upgrade pip before installing uvloop with:

$ pip install -U pip

As of uvloop 0.18, the preferred way of using it is via the uvloop.run() helper function:

import uvloop
async def main():
    # Main entry-point.
    ...
uvloop.run(main())

uvloop.run() works by simply configuring asyncio.run() to use uvloop, passing all of the arguments to it, such as debug, e.g. uvloop.run(main(), debug=True).

With Python 3.11 and earlier the following alternative snippet can be used:

import asyncio
import sys
import uvloop
async def main():
    # Main entry-point.
    ...
if sys.version_info >= (3, 11):
    with asyncio.Runner(loop_factory=uvloop.new_event_loop) as runner:
        runner.run(main())
else:
    uvloop.install()
    asyncio.run(main())

To build uvloop, you'll need Python 3.8 or greater:

1. Clone the repository:

   $ git clone --recursive git@github.com:MagicStack/uvloop.git
   $ cd uvloop
   

2. Create a virtual environment and activate it:

   $ python3 -m venv uvloop-dev
   $ source uvloop-dev/bin/activate
   

3. Install development dependencies:

   $ pip install -e .[dev]
   

4. Build and run tests:

   $ make
   $ make test
   

uvloop is dual-licensed under MIT and Apache 2.0 licenses.