[py] Use daemon threads for WebSocket connections

[cgoldberg]

User description

🔗 Related Issues

Fixes #16294
Fixes: #16621

💥 What does this PR do?

This PR makes the threads used for WebSockets into "daemon threads". This probably doesn't make much practical difference, but it will alleviate an annoying condition where you just want to exit a program, but for some reason the WebSocket connection or callback is hanging.

With the daemon flag, all threads will be abruptly killed on interpreter shutdown.

See: #16294 for more information

🔄 Types of changes

• Bug fix (backwards compatible)

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PR Type

Bug fix

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Description

• Convert WebSocket threads to daemon threads for proper shutdown

• Prevents hanging threads from blocking interpreter exit

• Applies to both main WebSocket connection and callback threads

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Diagram Walkthrough

flowchart LR
  A["WebSocket Connection"] --> B["Main Thread"]
  A --> C["Callback Threads"]
  B --> D["Daemon Thread"]
  C --> E["Daemon Threads"]
  D --> F["Clean Shutdown"]
  E --> F

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File Walkthrough

	Relevant files
Bug fix	websocket_connection.py Convert WebSocket threads to daemon threads                            py/selenium/webdriver/remote/websocket_connection.py Added daemon=True parameter to main WebSocket thread creation Added daemon=True parameter to callback thread creation Ensures threads don't prevent interpreter shutdown +2/-2

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[qodo-code-review]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Behavior Change Daemonizing the main WebSocket thread means it may terminate abruptly during interpreter shutdown, potentially dropping in-flight messages or leaving cleanup callbacks unexecuted. Confirm this is acceptable for all consumers and that shutdown paths do not rely on graceful thread joins. self._ws_thread = Thread(target=run_socket, daemon=True) self._ws_thread.start() Callback Side Effects Running callbacks on daemon threads can interrupt user code mid-execution at shutdown, which may cause partial state updates or resource leaks. Validate that callbacks are idempotent, short-lived, and do not require guaranteed completion or critical cleanup. params = message["params"] for callback in self.callbacks.get(message["method"], []): Thread(target=callback, args=(params,), daemon=True).start()

[qodo-code-review]

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[navin772]

LGTM!