L. C. Hsieh created SPARK-33827:
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Summary: Unload State Store asap once it becomes inactive
Key: SPARK-33827
URL: https://issues.apache.org/jira/browse/SPARK-33827
Project: Spark
Issue Type: Improvement
Components: Structured Streaming
Affects Versions: 3.2.0
Reporter: L. C. Hsieh
SS maintains state stores in executors across batches. Due to the nature of
Spark scheduling, a state store might be allocated on another executor in next
batch. The state store in previous batch becomes inactive.
Now we run a maintenance task periodically to unload inactive state stores. So
there will be some delays between a state store becomes inactive and it is
unloaded.
Per the discussion on https://github.com/apache/spark/pull/30770 with
[~kabhwan], I think the preference is to unload inactive state asap.
However, we can force Spark to always allocate a state store to same executor,
by using task locality configuration. This can reduce the possibility to have
inactive state store.
Normally, I think with locality configuration, we might not able to see
inactive state store generally. There is still chance an executor can be failed
and reallocated, but in this case, inactive state store is also lost too. So it
is not an issue.
The required change to make driver-executor bi-directional for state store
management looks non-trivial. If we already can reduce possibility of inactive
store, is it still worth making non-trivial here?
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