[jira] [Created] (SPARK-37556) Deser void class fail with Java serialization

["Daniel Dai (Jira)" <ji...@apache.org>]

Daniel Dai created SPARK-37556:
----------------------------------

             Summary: Deser void class fail with Java serialization
                 Key: SPARK-37556
                 URL: https://issues.apache.org/jira/browse/SPARK-37556
             Project: Spark
          Issue Type: Bug
          Components: Spark Core
    Affects Versions: 3.2.0
            Reporter: Daniel Dai


Spark code contains Java void type cannot be serialized with JavaSerializer. For example:
{code:java}
class Foo extends Serializable {
  Class k = Void.TYPE;
}
{code}
Spark will throw error:
{code:java}
java.lang.Void; local class name incompatible with stream class name "void"
	at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:703)
	at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1940)
	at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1806)
	at java.io.ObjectInputStream.readClass(ObjectInputStream.java:1771)
        ......
{code}
All other primitive type works. The reason is when SPARK-8730 try to fix the primitive type deserialization, it introduces the [following code|https://github.com/apache/spark/blob/v3.2.0/core/src/main/scala/org/apache/spark/serializer/JavaSerializer.scala#L80]:
{code:java}
private object JavaDeserializationStream {
  val primitiveMappings = Map[String, Class[_]](
    "boolean" -> classOf[Boolean],
    "byte" -> classOf[Byte],
    "char" -> classOf[Char],
    "short" -> classOf[Short],
    "int" -> classOf[Int],
    "long" -> classOf[Long],
    "float" -> classOf[Float],
    "double" -> classOf[Double],
    "void" -> classOf[Void]
  )
}
{code}
However, classOf[Void] is not the equivalence of other types. It's point to Void.class not Void.Type. The equivalence for void should be classOf[Unit]:
{code:java}
scala> classOf[Long]
val res0: Class[Long] = long

scala> classOf[Double]
val res1: Class[Double] = double

scala> classOf[Byte]
val res2: Class[Byte] = byte

scala> classOf[Void]
val res3: Class[Void] = class java.lang.Void  <--- this is wrong

scala> classOf[Unit]
val res4: Class[Unit] = void <---- this is right
{code}



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