fix: async state machine fails after pickle/multiprocessing #547
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When an async state machine is pickled and unpickled (e.g., via multiprocessing.Process), calling activate_initial_state() fails. The root cause is that __setstate__ recreates the engine but doesn't call engine.start(), so the initial __initial__ event is never enqueued. This commit adds self._engine.start() to __setstate__ so the initial transition is properly enqueued after deserialization. Fixes fgmacedo#544 Signed-off-by: rodrigo.nogueira <rodrigo.nogueira@prf.gov.br>
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Description
When an async state machine is pickled and unpickled (e.g., via
multiprocessing.Process), callingactivate_initial_state()fails withInvalidStateValue: There's no current state set.Root Cause
In
__setstate__, the engine is recreated butengine.start()is never called, so the initial__initial__event is never enqueued. When the user callsawait sm.activate_initial_state(), there's nothing in the queue to process.Fix
Added
self._engine.start()to__setstate__so the initial transition is properly enqueued after deserialization.Testing
Added regression test
test_pickle_async_statemachineintests/test_copy.py.Fixes #544