websockets

The websockets library has been rock-solid in production for me across multiple high-throughput services. The async/await API feels natural and composable - you write `async for message in websocket` and it just works. Connection lifecycle management is straightforward with proper context managers that handle cleanup automatically. The library exposes useful hooks for ping/pong keepalives with configurable intervals, and I've never had mystery disconnections when tuning these properly.

Performance is excellent - minimal overhead and memory usage stays predictable even with thousands of concurrent connections. The built-in support for compression (permessage-deflate) is a huge win for bandwidth-sensitive applications. Error handling is explicit and well-documented; exceptions like ConnectionClosed give you the close code and reason, making debugging straightforward.

One gotcha: the default timeout behavior changed between major versions, so pinning versions and reading changelogs carefully is essential. The library provides good logging hooks through Python's standard logging module, and you can instrument connection state transitions easily. Under load, it degrades gracefully without mystery hangs or resource leaks.

The websockets library is hands-down the most polished WebSocket implementation for Python. The async/await API is intuitive and integrates seamlessly with asyncio patterns. Connection handling is rock-solid - automatic ping/pong keeps connections alive, and the library handles close handshakes properly by default. Memory usage is lean even with thousands of concurrent connections, and the built-in connection state machine prevents common edge cases.

What sets this apart operationally is the thoughtful error handling. Exceptions are well-structured (ConnectionClosed, InvalidState, etc.) making retry logic straightforward. Timeouts are configurable at every level - open, close, ping intervals. The logging integration exposes exactly what you need for debugging without overwhelming you. Compression (permessage-deflate) works out of the box and yields significant bandwidth savings.

The documentation includes production patterns like proper shutdown sequences and broadcast strategies. Breaking changes between major versions are clearly documented. My only gripes: you need to implement your own connection pooling for client scenarios, and there's no built-in reconnection logic (though this keeps the library focused). Performance under load is excellent - I've run 10k+ concurrent connections per process without issues.

The websockets library nails the developer experience with a straightforward async/await API that feels natural in modern Python. Getting started is genuinely easy - the basic client/server examples in the docs work immediately and cover 90% of common use cases. The `connect()` and `serve()` functions are intuitive, and context managers handle cleanup automatically, which prevents the resource leaks I've dealt with in other libraries.

Error messages stand out as exceptionally helpful. When connections fail, you get clear exceptions with specific reasons (connection refused, handshake errors, protocol violations). The library distinguishes between network issues and protocol problems, making debugging much faster. Stack traces are clean and point to your code, not deep into framework internals.

The documentation includes a cookbook section with copy-paste examples for authentication, broadcasting, reconnection logic, and health checks. GitHub issues get responses within days, often from the maintainer himself. The only learning curve involves understanding asyncio itself, but if you're already comfortable with async Python, you'll be productive within an hour.