Limitation of serialization

Serializing by implementing Serializable interface has some issues. Lets see one by one what they are.

Performance issues:

• Serialization is a recursive algorithm. What I mean to say here is, apart from the fields that are required, starting from a single object, until all the objects that can be reached from that object by following instance variables, are also serialized. This includes the super class of the object until it reaches the "Object" class and the same way the super class of the instance variables until it reaches the "Object" class of those variables. Basically all the objects that it can read. This leads to lot of overheads. Say for example, you need only car type and licence number but using serialization, you cannot stop there. All the information that includes description of car, its parts, blah blah will be serialized. Obviously this slows down the performance.
  
• Both serializing and deserializing require the serialization mechanism to discover information about the instance it is serializing. Using the default serialization mechanism, will use reflection to discover all the field values. Also the information about class description is added to the stream which includes the descption of all the serializable superclasses, the description of the class and the instance data associated with the specific instance of the class. Lots of data and metadata and again performance issue.
  
• You know that serialization needs serialVersionUID, a unique Id to identify the information persisted. If you dont explicitly set a serialiVersionUID, serialization will compute the serialiVersionUID by going through all the fields and methods. So based on the size of the class, again serialization mechanism takes respective amount of time to calculate the value. A third performance issue.

Other issues
Above three points confirm serialization has performance issues. Apart from performance issues,
When an object that implements Serializable interface, is serialized or de-serialized, no constructor of the object is called and hence any initialization which is done in the constructor cannot be done. Although there is an alternative of writing all initialization logic in a separate method and call it in constructor and readObject methods so that when an object is created or deserialized, the initialization process can happen but it definitely is a messy approach.