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Stop the broadcaster from losing cancellations on Python 3.11 - #7
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asyncio.wait_for on 3.11 returns normally when it is cancelled just as the wrapped send completes. gather then raises a bare CancelledError that anyio does not recognise as its own, so cancelling a hub or browser handler during a broadcast could leak the cancellation. This made test_hub_ws fail in about half of CI runs and blocked deploys. asyncio.timeout handles cancellation correctly and keeps the same per-client send timeout. Co-Authored-By: Claude Opus 5.5 <[email protected]>
hyperloop-cornell
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Oct 14, 2026
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lgtm
simple timeout fix
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Summary
Broadcaster._sendnow usesasyncio.timeout()instead ofasyncio.wait_for()for the per-client send timeout.wait_forreturns normally if it is cancelled just as the wrapped send finishes, so the cancellation is lost.gatherthen raises a bareCancelledErrorthat anyio doesn't recognise as its own, and the error escapes the cancel scope.concurrent.futures.CancelledErrorfromWebSocketTestSession.__exit__intests/test_hub_ws.py. Which test fails varies; it is usuallytest_hub_status_broadcast. Since at least Sep 27 it has failed the hyperloop-guitest-apijob in about half of runs.SEND_TIMEOUT_SECONDSstill raisesTimeoutErrorand is dropped.test_slow_browser_is_droppedstill passes.Merge notes
hyperloop-cornell/hyperloop-gui#23 pins this branch's commit (
46e47f2), so merge this PR first and use a merge commit (not squash). Otherwise the pinned commit is not onmain.Test plan
tests/test_hub_ws.py100 times on Python 3.11 (python:3.11-slim, same as CI): 50/100 runs failed before the fix, 0/100 afterwait_for; full suite 80 passed🤖 Generated with Claude Code