Genmao Yu created SPARK-29438:
---------------------------------
Summary: Failed to get state store in stream-stream join
Key: SPARK-29438
URL: https://issues.apache.org/jira/browse/SPARK-29438
Project: Spark
Issue Type: Bug
Components: Structured Streaming
Affects Versions: 2.4.4
Reporter: Genmao Yu
Now, Spark use the `TaskPartitionId` to determine the StateStore path.
{code:java}
TaskPartitionId \
StateStoreVersion --> StoreProviderId -> StateStore
StateStoreName /
{code}
In spark stages, the task partition id is determined by the number of tasks. As
we said the StateStore file path depends on the task partition id. So if
stream-stream join task partition id is changed against last batch, it will get
wrong StateStore data or fail with non-exist StateStore data. In some corner
cases, it happened:
{code:java}
val df3 = streamDf1.join(streamDf2)
val df5 = streamDf3.join(batchDf4)
val df = df3.union(df5)
df.writeStream...start()
{code}
A simplified DAG like this:
{code:java}
DataSourceV2Scan Scan Relation DataSourceV2Scan DataSourceV2Scan
(streamDf3) | (streamDf1) (streamDf2)
| | | |
Exchange(200) Exchange(200) Exchange(200) Exchange(200)
| | | |
Sort Sort | |
\ / \ /
\ / \ /
SortMergeJoin StreamingSymmetricHashJoin
\ /
\ /
\ /
Union
{code}
Stream-Steam join task Id will start from 200 to 399 as they are in the same
stage with `SortMergeJoin`. But when there is no new incoming data in
`streamDf3` in some batch, it will generate a empty LocalRelation, and then the
SortMergeJoin will be replaced with a BroadcastHashJoin. In this case,
Stream-Steam join task Id will start from 1 to 200. Finally, it will get wrong
StateStore path through TaskPartitionId, and failed with error reading state
store delta file.
{code:java}
LocalTableScan Scan Relation DataSourceV2Scan DataSourceV2Scan
| | | |
BroadcastExchange | Exchange(200) Exchange(200)
| | | |
| | | |
\ / \ /
\ / \ /
BroadcastHashJoin StreamingSymmetricHashJoin
\ /
\ /
\ /
Union
{code}
In my job, I closed the auto BroadcastJoin feature (set
spark.sql.autoBroadcastJoinThreshold=false) to walk around this bug. We should
make the StateStore path determinate but not depends on TaskPartitionId.
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