{"id":458,"library":"uvloop","title":"uvloop","description":"uvloop is a fast, drop-in replacement for Python's built-in asyncio event loop, implemented in Cython and built on top of libuv. The current version is 0.22.1, and it follows a regular release cadence with active maintenance.","status":"active","version":"0.22.1","language":"python","source_language":"en","source_url":"https://github.com/MagicStack/uvloop","tags":["asyncio","event loop","libuv","Python 3.8+"],"install":[{"cmd":"pip install uvloop","lang":"bash","label":"Install uvloop"}],"dependencies":[{"reason":"uvloop is built on top of libuv, a high-performance asynchronous I/O library.","package":"libuv"}],"imports":[{"note":"Ensure that uvloop is installed and imported correctly.","symbol":"uvloop","correct":"import uvloop"}],"quickstart":{"code":"import asyncio\nimport uvloop\n\nasync def main():\n    # Your asynchronous code here\n    pass\n\nuvloop.run(main())","lang":"python","description":"A basic example demonstrating how to use uvloop as the event loop for asyncio applications."},"warnings":[{"fix":"Consider using a different event loop implementation on Windows.","message":"uvloop does not support Windows at the moment.","severity":"breaking","affected_versions":"all"},{"fix":"Verify compatibility with your Python version before using uvloop.","message":"uvloop may not be compatible with Python versions beyond 3.13.","severity":"breaking","affected_versions":"3.14 and above"},{"fix":"Implement additional error handling to manage closed connections appropriately.","message":"uvloop may not handle closed connections gracefully in certain scenarios.","severity":"gotcha","affected_versions":"all"}],"env_vars":null,"last_verified":"2026-05-12T13:56:59.546Z","next_check":"2026-06-26T00:00:00.000Z","problems":[{"fix":"pip install uvloop","cause":"The `uvloop` package has not been installed in the active Python environment.","error":"ModuleNotFoundError: No module named 'uvloop'"},{"fix":"Install the Microsoft C++ Build Tools via the provided link or Visual Studio Installer, then retry `pip install uvloop`.","cause":"`uvloop` is a Cython extension that requires a C compiler to build from source, which is often missing on Windows systems by default.","error":"error: Microsoft Visual C++ 14.0 or greater is required. Get it with 'Microsoft C++ Build Tools': https://visualstudio.microsoft.com/visual-cpp-build-tools/"},{"fix":"Install the `libuv` development package for your operating system (e.g., `sudo apt-get install libuv1-dev` on Debian/Ubuntu, `brew install libuv` on macOS).","cause":"When `pip` attempts to build `uvloop` from source (e.g., if a pre-built wheel isn't available), the `libuv` development headers are missing from the system.","error":"fatal error: 'uv.h' file not found"}],"ecosystem":"pypi","meta_description":null,"install_score":100,"install_tag":"verified","quickstart_score":80,"quickstart_tag":"verified","pypi_latest":null,"install_checks":{"last_tested":"2026-05-12","tag":"verified","tag_description":"installs cleanly on critical runtimes, fast import, recently tested","results":[{"runtime":"python:3.10-alpine","python_version":"3.10","os_libc":"alpine (musl)","variant":"default","exit_code":0,"wheel_type":null,"failure_reason":null,"install_time_s":null,"import_time_s":0.09,"mem_mb":4.6,"disk_size":"27.2M"},{"runtime":"python:3.10-slim","python_version":"3.10","os_libc":"slim (glibc)","variant":"default","exit_code":0,"wheel_type":null,"failure_reason":null,"install_time_s":null,"import_time_s":0.06,"mem_mb":4.6,"disk_size":"31M"},{"runtime":"python:3.11-alpine","python_version":"3.11","os_libc":"alpine (musl)","variant":"default","exit_code":0,"wheel_type":null,"failure_reason":null,"install_time_s":null,"import_time_s":0.2,"mem_mb":5.6,"disk_size":"29.3M"},{"runtime":"python:3.11-slim","python_version":"3.11","os_libc":"slim (glibc)","variant":"default","exit_code":0,"wheel_type":null,"failure_reason":null,"install_time_s":null,"import_time_s":0.14,"mem_mb":5.6,"disk_size":"33M"},{"runtime":"python:3.12-alpine","python_version":"3.12","os_libc":"alpine (musl)","variant":"default","exit_code":0,"wheel_type":null,"failure_reason":null,"install_time_s":null,"import_time_s":0.41,"mem_mb":8.2,"disk_size":"23.1M"},{"runtime":"python:3.12-slim","python_version":"3.12","os_libc":"slim (glibc)","variant":"default","exit_code":0,"wheel_type":null,"failure_reason":null,"install_time_s":null,"import_time_s":0.34,"mem_mb":8.2,"disk_size":"28M"},{"runtime":"python:3.13-alpine","python_version":"3.13","os_libc":"alpine (musl)","variant":"default","exit_code":0,"wheel_type":null,"failure_reason":null,"install_time_s":null,"import_time_s":0.41,"mem_mb":8.7,"disk_size":"22.7M"},{"runtime":"python:3.13-slim","python_version":"3.13","os_libc":"slim (glibc)","variant":"default","exit_code":0,"wheel_type":null,"failure_reason":null,"install_time_s":null,"import_time_s":0.33,"mem_mb":8.7,"disk_size":"27M"},{"runtime":"python:3.9-alpine","python_version":"3.9","os_libc":"alpine (musl)","variant":"default","exit_code":0,"wheel_type":null,"failure_reason":null,"install_time_s":null,"import_time_s":0.09,"mem_mb":4.5,"disk_size":"26.6M"},{"runtime":"python:3.9-slim","python_version":"3.9","os_libc":"slim (glibc)","variant":"default","exit_code":0,"wheel_type":null,"failure_reason":null,"install_time_s":null,"import_time_s":0.07,"mem_mb":4.5,"disk_size":"30M"}]},"quickstart_checks":{"last_tested":"2026-04-23","tag":"verified","tag_description":"quickstart runs on critical runtimes, recently tested","results":[{"runtime":"python:3.10-alpine","exit_code":0},{"runtime":"python:3.10-slim","exit_code":0},{"runtime":"python:3.11-alpine","exit_code":0},{"runtime":"python:3.11-slim","exit_code":0},{"runtime":"python:3.12-alpine","exit_code":0},{"runtime":"python:3.12-slim","exit_code":0},{"runtime":"python:3.13-alpine","exit_code":0},{"runtime":"python:3.13-slim","exit_code":0},{"runtime":"python:3.9-alpine","exit_code":0},{"runtime":"python:3.9-slim","exit_code":0}]}}