wypoon commented on a change in pull request #26895: [SPARK-17398][SQL] Fix
ClassCastException when querying partitioned JSON table
URL: https://github.com/apache/spark/pull/26895#discussion_r358000739
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File path: sql/hive/src/main/scala/org/apache/spark/sql/hive/TableReader.scala
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@@ -132,7 +132,9 @@ class HadoopTableReader(
val deserializedHadoopRDD = hadoopRDD.mapPartitions { iter =>
val hconf = broadcastedHadoopConf.value.value
val deserializer = deserializerClass.getConstructor().newInstance()
- deserializer.initialize(hconf, localTableDesc.getProperties)
+ DeserializerLock.synchronized {
Review comment:
I don't think there will be a lot of contention. We call
`deserializer.initialize` once for each partition.
The race is actually in
`HCatRecordObjectInspectorFactory.getHCatRecordObjectInspector` which is called
by `JsonSerDe#initialize` (the factory uses a `HashMap` instead of , e.g., a
`ConcurrentHashMap` to maintain a cache). We want the same `ObjectInspector` to
be returned by the factory cache and set in each `JsonSerDe` instance as its
`ObjectInspector`.
Our objective is that there not be more than one task from each executor
calling `JsonSerDe#initialize` at the same time.
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