Alexis Sarda-Espinosa created SPARK-26980:
---------------------------------------------
Summary: Kryo deserialization not working with KryoSerializable
class
Key: SPARK-26980
URL: https://issues.apache.org/jira/browse/SPARK-26980
Project: Spark
Issue Type: Bug
Components: SQL
Affects Versions: 2.4.0
Environment: Local Spark v2.4.0
Kotlin v1.3.21
Reporter: Alexis Sarda-Espinosa
I'm trying to create an {{Aggregator}} that uses a custom container that should
be serialized with {{Kryo}}:
{code:java}
class StringSet(other: Collection<String>) : HashSet<String>(other),
KryoSerializable {
companion object {
@JvmStatic
private val serialVersionUID = 1L
}
constructor() : this(Collections.emptyList())
override fun write(kryo: Kryo, output: Output) {
output.writeInt(this.size)
for (string in this) {
output.writeString(string)
}
}
override fun read(kryo: Kryo, input: Input) {
val size = input.readInt()
repeat(size) { this.add(input.readString()) }
}
}
{code}
However, if I look at the corresponding value in the {{Row}} after aggregation
(for example by using {{collectAsList()}}), I see a {{byte[]}}. Interestingly,
the first byte in that array seems to be some sort of noise, and I can
deserialize by doing something like this:
{code:java}
val b = row.getAs<ByteArray>(2)
val input = Input(b.copyOfRange(1, b.size)) // extra byte?
val set = Kryo().readObject(input, StringSet::class.java)
{code}
Used configuration:
{code:java}
SparkConf()
.setAppName("Hello Spark with Kotlin")
.set("spark.serializer", "org.apache.spark.serializer.KryoSerializer")
.set("spark.kryo.registrationRequired", "true")
.registerKryoClasses(arrayOf(StringSet::class.java))
{code}
[Sample repo with all the
code|https://github.com/asardaes/hello-spark-kotlin/tree/8e8a54fd81f0412507318149841c69bb17d8572c].
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