fix: add lock to flow control #899
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daniel-sanche commented Dec 12, 2023
| with self._lock: | ||
| self.inflight_mutations += batch_info.mutations_count | ||
| self.inflight_size += batch_info.mutations_size | ||
| self.set_flow_control_status() |
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I believe we can keep set_flow_control_status out of the lock. Even if it occasionally gets clobbered by later changes, every add and release ends with another call to set_flow_control_status, so it should be eventually correct.
igorbernstein2 approved these changes Dec 12, 2023
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The MutationBatcher's _FlowControl class currently can experience a race condition, where the release of resources can be clobbered by a different thread adding resources to the flow. This can result in deadlock, where the flow is empty, but remains blocked waiting on mutations that are already complete
This PR adds a mutex lock, ensuring that only one thread has access to the flow control state at a time.