concurrent.futures.TimeoutError not caught on Python 3.9/3.10 — timeout silently uncaught

[FernandoCelmer]

Description

_execute_with_timeout in core/engine.py calls future.result(timeout=seconds), which raises concurrent.futures.TimeoutError on expiry. The catch block at lines 134 and 176 catches bare TimeoutError (the builtin).

On Python 3.9 and 3.10, concurrent.futures.TimeoutError is a separate class that inherits directly from Exception, not from builtins.TimeoutError. This means the timeout is never caught on those versions.

Location

dotflow/core/engine.py — lines 134, 170-178

Current Behavior

except TimeoutError:
    future.cancel()
    raise TimeoutError()

On Python 3.9/3.10, concurrent.futures.TimeoutError propagates uncaught, bypasses retry logic, and the task is marked FAILED with a confusing generic error instead of a proper TimeoutError.

Expected Behavior

Both builtins.TimeoutError and concurrent.futures.TimeoutError should be caught:

from concurrent.futures import TimeoutError as FuturesTimeoutError

except (TimeoutError, FuturesTimeoutError):
    future.cancel()
    raise TimeoutError()

Impact

• Severity: Critical
• Affected versions: Python 3.9, 3.10
• Symptom: Timeout never triggers properly, task crashes with unhandled exception

Priority

Critical