Brussels / 31 January & 1 February 2015


Packed Objects, Object Layout & Value Types - a Survey

Java is often criticized for its lack of supporting C-style structs. This makes it hard to efficiently implement certain type of data structures (like for example arrays of small objects) in Java.

However, recently there have been several different approaches which try to address this problem. My talk will briefly introduce "Packed Objects", an extension available in IBM's Java SDK 8, "Object Layout", a layout-optimized Java data structure package proposed by Azul Systems and Value Types [3][4], an OpenJDK proposal for immutable, reference-free value objects.

I will describe the commonalities and differences of the three approaches and explain how they can improve the memory overhead and locality of Java objects.


Photo of Volker Simonis Volker Simonis