Special care must be taken when serializing Writable items. The
hazelcast-jet-hadoop module implements out-of-the-box serialization support
for some of the primitive types including the following:
-
BooleanWritable -
ByteWritable -
DoubleWritable -
FloatWritable -
IntWritable -
LongWritable -
Text
Anything outside of these types falls back to a default implementation
for all Writable types which writes the full class name and the fields
per item. When deserializing, the class name is read first and the
deserialized instance is created using the classloader and reflection.
The explicitly registered types only write a single integer as a type id
and do not use reflection for deserialization.
To explicitly register your own Writable types for fast serialization,
you can extend the provided WritableSerializerHook class and register
the hook with Hazelcast.