Fix potential race condition between evaluator and partition #1295
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tobim
previously approved these changes
Jan 21, 2021
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From looking at the changes, this seems to be correct and I do believe that the issue is real. I think one potential symptom is that a query_supervisor would miss a response from the cleaned-up partition and stay in limbo eternally, which in turn would block the corresponding exporter from iterating through the remaining candidate partitions.
tobim
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Jan 21, 2021
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@lava can you rebase onto master? |
The partition currently assumes strict ownership of its indexers, and terminates them when it shuts down. However, the evaluator did not store a partition handle but just the handles of the relevant indexers. This could lead to a race condition between an evaluator and a partition when an active partition finished persisting right when a new query was spawned, or when a query took long enough to see its associated passive partition evicted from the LRU cache.
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@dominiklohmann Sorry, didn't notice until after I pushed. Done. |
dominiklohmann
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Jan 25, 2021
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Ignoring the mac CI fault since it is https://app.clubhouse.io/tenzir/story/20882/race-condition-in-node-queries-unit-test again. |
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📔 Description
This came up while pairing on on unrelated PR with @tobim . I have no proof that the described race can actually happen in practice, but intuitively it makes sense to me that it would.
📝 Checklist