Currently Java objects have a 128-bit object header in the 64-bit HotSpot VM, with a 64-bit multipurpose header word and a 64-bit class pointer. With average object sizes of five to six words, ...

JEP 450 (Compact Object Headers) has been targeted for delivery in JDK 24, and has already been merged to main. This currently experimental feature optimizes heap utilization by shrinking the size ...

Java 25 introduces Compact Object Headers (JEP 519), delivering up to 30% CPU savings and reduced memory usage for applications with small objects. This user-friendly feature compresses object headers ...

To coordinate shared data access among multiple threads, the Java virtual machine associates a lock with each object and class. A lock is like a privilege that only one thread can “possess” at ...