winloop

What it is and what it does

Winloop is a Windows port of uvloop, the high-performance asyncio event loop implementation. It replaces Python's standard Windows asyncio event loops with a libuv-based alternative designed to handle network I/O more efficiently. The package is maintained as an active fork because uvloop itself does not support Windows; Winloop removes Windows-incompatible features like forking and adapts subprocess handling to work within Windows constraints.

The library is intended for developers running asyncio applications on Windows who need better performance than the standard library provides. It requires calling `winloop.install()` to activate the custom event loop policy. Pre-built wheels are available for modern Python versions on Windows, though building from source requires Visual C++ build tools and Cython.

Use it for:

• Accelerate web servers on Windows by replacing the default asyncio event loop.
• Improve TCP connection handling performance in Windows-based async networking applications.
• Work around SSL issues reported with Python 3.9 Windows asyncio event loop policies.
• Develop high-throughput async I/O applications on Windows without porting to Linux.
• Benchmark asyncio application performance improvements by swapping event loop implementations.

Worth the install?

AI-flagged interpretation of the facts on this page — verify before relying

Winloop is a Windows-compatible alternative to uvloop that replaces the standard asyncio event loop with a faster, libuv-based implementation optimized for Windows.

Yes, if you run asyncio applications on Windows and need better I/O performance. The package is actively maintained, has no known vulnerabilities, and offers pre-built wheels for most Python versions. Install friction is moderate (requires build tools if compiling, but wheels are available). The MIT License is permissive. Main caveat: verify that your specific asyncio framework or libraries work correctly with the API changes Winloop introduces.

Install

winloop on PyPI

pip install winloop

uv add winloop

poetry add winloop

Installing winloop

Before you install

Medium install friction: compiled extension requiring Visual C++ build tools on Windows. Active maintenance with recent commits and no known vulnerabilities. Supports Python 3.8 through 3.14 with pre-built wheels for Windows x64 and ARM64.

License in practice

Licensed under MIT License with permissive treatment. No restrictions on commercial use, modification, or distribution; suitable for proprietary projects.

Quickstart

pip install winloop

import asyncio
import winloop

winloop.install()
# Now asyncio uses the winloop event loop
loop = asyncio.get_event_loop()

Requires Visual C++ build tools to compile from source on Windows. Pre-built wheels are available for Python 3.8–3.14 on Windows x64 and ARM64, so pip install typically works without compilation.

Verify before relying

• Actual performance improvement magnitude compared to standard Windows asyncio policies in real-world applications.
• Compatibility with all asyncio-based frameworks given the API changes mentioned in the description.
• Whether SSL problem resolution on Python 3.9 Windows is confirmed across current Python versions.

Package facts

Evidence: winloop-0.6.3-cp310-cp310-win_amd64.whl; winloop-0.6.3-cp310-cp310-win_arm64.whl; winloop-0.6.3-cp311-cp311-win_amd64.whl; winloop-0.6.3-cp311-cp311-win_arm64.whl; winloop-0.6.3-cp312-cp312-win_amd64.whl; winloop-0.6.3-cp312-cp312-win_arm64.whl; winloop-0.6.3-cp313-cp313-win_amd64.whl; winloop-0.6.3-cp313-cp313-win_arm64.whl; winloop-0.6.3-cp314-cp314t-win_amd64.whl; winloop-0.6.3-cp314-cp314t-win_arm64.whl; winloop-0.6.3-cp314-cp314-win_amd64.whl; winloop-0.6.3-cp314-cp314-win_arm64.whl; winloop-0.6.3-cp38-cp38-win_amd64.whl; winloop-0.6.3-cp39-cp39-win_amd64.whl; winloop-0.6.3-cp39-cp39-win_arm64.whl

Keywords: asyncio, networking

Tags

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