public interface Serializer
SerializerInstanceobjects that do the actual serialization and are guaranteed to only be called from one thread at a time.
Implementations of this trait should implement:
1. a zero-arg constructor or a constructor that accepts a
as parameter. If both constructors are defined, the latter takes precedence.
2. Java serialization interface.
Note that serializers are not required to be wire-compatible across different versions of Spark. They are intended to be used to serialize/de-serialize data within a single Spark application.