[aclark4life]

PYTHON-6187

Changes in this PR

• _run_command in both the async and sync command runners now catches BaseException instead of Exception, so a cancellation (asyncio.CancelledError) and, in the sync driver, KeyboardInterrupt/SystemExit publish the CommandFailedEvent and "Command failed" log message before the exception propagates, as the Command Logging and Monitoring spec guarantees.
• Exceptions that stringify to "" (CancelledError, KeyboardInterrupt, SystemExit) get an errmsg of operation interrupted by <ClassName> instead of an empty message.
• _convert_exception now annotates its parameter as BaseException.
• Changelog entry for 4.21.0.

Test Plan

• New regression test in test/asynchronous/test_async_cancellation.py: cancel a blocked find (failCommand blockConnection) and assert a correlating CommandFailedEvent with errtype == "CancelledError". Verified it fails without the fix and passes with it.
• test_monitoring.py, test_command_monitoring.py, test_command_logging.py, and test_async_cancellation.py pass for both async and sync suites (167 passed).
• just typing passes.

Checklist

Checklist for Author

• Did you update the changelog (if necessary)?
• Is the intention of the code captured in relevant tests?
• If there are new TODOs, has a related JIRA ticket been created?

Checklist for Reviewer

• Does the title of the PR reference a JIRA Ticket?
• Do you fully understand the implementation? (Would you be comfortable explaining how this code works to someone else?)
• Have you checked for spelling & grammar errors?
• Is all relevant documentation (README or docstring) updated?

[Copilot]

🟡 Changes recommended

The cancellation test relies on a 100 ms sleep rather than confirming that find has started, so it can fail spuriously and needs bounded event synchronization with guaranteed task cleanup.

1 open issue

• Wait for find to start before cancelling the task · New

What changed in this PR

This PR fixes command monitoring for interrupted operations so cancellation publishes a corresponding failure event and log message before the exception propagates.

Changes:

• Catch BaseException in command runners and provide fallback messages for empty exception text.
• Add an async cancellation regression test checking correlated command events.
• Document the fix in the 4.21.0 changelog.

File	Description
test/​asynchronous/​test_async_cancellation.py	Adds cancellation-event regression coverage.
pymongo/​synchronous/​command_runner.py	Mirrors interruption handling in the generated sync runner.
pymongo/​message.py	Broadens the exception-conversion annotation to BaseException.
pymongo/​asynchronous/​command_runner.py	Publishes failure telemetry for cancelled commands.
doc/​changelog.rst	Records the cancellation-monitoring fix.

_{Review effort: Balanced}

[Copilot]

🟢 Approval recommended

No active review issues block approval of the command-monitoring and cancellation changes.

No open issues 🎉

1 resolved since last review

• Wait for find to start before cancelling the task

_{Review effort: Balanced}