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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

Using uvloop

As of uvloop 0.18, the preferred way of using it is via the helper function:

import uvloop

async def main():
    # Main entry-point.
    ... works by simply configuring to use uvloop, passing all of the arguments to it, such as debug, e.g., 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:

Building From Source

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

  1. Clone the repository:

    $ git clone --recursive
    $ cd uvloop
  2. Create a virtual environment and activate it:

    $ python3.7 -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.