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SerializerManager

SerializerManager is used to select the Serializer for shuffle blocks.

Creating Instance

SerializerManager takes the following to be created:

SerializerManager is created when:

Kryo-Compatible Types

Kryo-Compatible Types are the following primitive types, Arrays of the primitive types and Strings:

  • Boolean
  • Byte
  • Char
  • Double
  • Float
  • Int
  • Long
  • Null
  • Short

Default Serializer

SerializerManager is given a Serializer when created (based on spark.serializer configuration property).

The Serializer is used when SerializerManager is requested for a Serializer.

Tip

Enable DEBUG logging level of SparkEnv to be told about the selected Serializer.

Using serializer: [serializer]

Accessing SerializerManager

SerializerManager is available using SparkEnv on the driver and executors.

import org.apache.spark.SparkEnv
SparkEnv.get.serializerManager

KryoSerializer

SerializerManager creates a KryoSerializer when created.

KryoSerializer is used as the serializer when the types of a given key and value are Kryo-compatible.

Selecting Serializer

getSerializer(
  ct: ClassTag[_],
  autoPick: Boolean): Serializer
getSerializer(
  keyClassTag: ClassTag[_],
  valueClassTag: ClassTag[_]): Serializer

getSerializer returns the KryoSerializer when the given ClassTags are Kryo-compatible and the autoPick flag is true. Otherwise, getSerializer returns the default Serializer.

autoPick flag is true for all BlockIds but Spark Streaming's StreamBlockIds.

getSerializer (with autoPick flag) is used when:

getSerializer (with key and value ClassTags only) is used when:

dataSerializeStream

dataSerializeStream[T: ClassTag](
  blockId: BlockId,
  outputStream: OutputStream,
  values: Iterator[T]): Unit

dataSerializeStream...FIXME

dataSerializeStream is used when:

dataSerializeWithExplicitClassTag

dataSerializeWithExplicitClassTag(
  blockId: BlockId,
  values: Iterator[_],
  classTag: ClassTag[_]): ChunkedByteBuffer

dataSerializeWithExplicitClassTag...FIXME

dataSerializeWithExplicitClassTag is used when:

dataDeserializeStream

dataDeserializeStream[T](
  blockId: BlockId,
  inputStream: InputStream)
  (classTag: ClassTag[T]): Iterator[T]

dataDeserializeStream...FIXME

dataDeserializeStream is used when:


Last update: 2021-07-22
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