Zhenhao Li created SPARK-38091:
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Summary: AvroSerializer can cause java.lang.ClassCastException at
run time
Key: SPARK-38091
URL: https://issues.apache.org/jira/browse/SPARK-38091
Project: Spark
Issue Type: Bug
Components: SQL
Affects Versions: 3.2.1, 3.2.0, 3.1.2, 3.1.1, 3.1.0, 3.0.3, 3.0.2, 3.0.1,
3.0.0
Reporter: Zhenhao Li
`AvroSerializer`'s implementation, at least in `newConverter`, was not 100%
based on the `InternalRow` and `SpecializedGetters` interface. It assumes many
implementation details of the interface.
For example, in
```scala
case (TimestampType, LONG) => avroType.getLogicalType match {
// For backward compatibility, if the Avro type is Long and it is not
logical type
// (the `null` case), output the timestamp value as with millisecond
precision.
case null | _: TimestampMillis => (getter, ordinal) =>
DateTimeUtils.microsToMillis(timestampRebaseFunc(getter.getLong(ordinal)))
case _: TimestampMicros => (getter, ordinal) =>
timestampRebaseFunc(getter.getLong(ordinal))
case other => throw new IncompatibleSchemaException(errorPrefix +
s"SQL type ${TimestampType.sql} cannot be converted to Avro logical
type $other")
}
```
it assumes the `InternalRow` instance encodes `TimestampType` as
`java.lang.Long`. That's true for `Unsaferow` but not for `GenericInternalRow`.
Hence the above code will end up with runtime exceptions when used on an
instance of `GenericInternalRow`, which is the case for Python UDF.
I didn't get time to dig deeper than that. I got the impression that Spark's
optimizer(s) will turn a row into a `UnsafeRow` and Python UDF doesn't involve
the optimizer(s) and hence each row is a `GenericInternalRow`.
It would be great if someone can correct me or offer a better explanation.
To reproduce the issue,
`git checkout master` and `git cherry-pick --no-commit`
[this-commit|https://github.com/Zhen-hao/spark/commit/1ffe8e8f35273b2f3529f6c2d004822f480e4c88]
and run the test `org.apache.spark.sql.avro.AvroSerdeSuite`.
You will see runtime exceptions like the following one
```
- Serialize DecimalType to Avro BYTES with logical type decimal *** FAILED ***
java.lang.ClassCastException: class java.math.BigDecimal cannot be cast to
class org.apache.spark.sql.types.Decimal (java.math.BigDecimal is in module
java.base of loader 'bootstrap'; org.apache.spark.sql.types.Decimal is in
unnamed module of loader 'app')
at
org.apache.spark.sql.catalyst.expressions.BaseGenericInternalRow.getDecimal(rows.scala:45)
at
org.apache.spark.sql.catalyst.expressions.BaseGenericInternalRow.getDecimal$(rows.scala:45)
at
org.apache.spark.sql.catalyst.expressions.GenericInternalRow.getDecimal(rows.scala:195)
at
org.apache.spark.sql.avro.AvroSerializer.$anonfun$newConverter$10(AvroSerializer.scala:136)
at
org.apache.spark.sql.avro.AvroSerializer.$anonfun$newConverter$10$adapted(AvroSerializer.scala:135)
at
org.apache.spark.sql.avro.AvroSerializer.$anonfun$newStructConverter$2(AvroSerializer.scala:283)
at org.apache.spark.sql.avro.AvroSerializer.serialize(AvroSerializer.scala:60)
at
org.apache.spark.sql.avro.AvroSerdeSuite.$anonfun$new$5(AvroSerdeSuite.scala:82)
at
org.apache.spark.sql.avro.AvroSerdeSuite.$anonfun$new$5$adapted(AvroSerdeSuite.scala:67)
at
org.apache.spark.sql.avro.AvroSerdeSuite.$anonfun$withFieldMatchType$2(AvroSerdeSuite.scala:217)
```
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