Generational ZGC- An Improvement in Garbage Collector in Java 21

Java support the garbage collection automatically. However, with the introduce of JRE7 it introduces the hotspot Architecture having heap, where object data is stored. Garbage Collection based on Responsiveness and Throughput. The overall Automatic Garbage Collection have three steps Marking, Normal Deletion, Deletion with Compacting to complete the cycle. However, the collection of all objects and marking them is difficult with help of JVM. As JVM divides the heap parts as: Young Generation, Old or Tenured Generation and Permanent Generation. To overcome this, we introduce ZGC (Garbage Collector) introduce in Java 11. ZGC is concurrent, region -based, compact, NUMA-aware, using coloured pointers, using load barriers technique. However, with release of Java 21, we introduce Generational ZGC which maintain separate generators for old and young Generation. Generational ZGC heap memory overhead, lower risks of allocation stalls and lower garbage collection CPU overhead. This paper represents ZGC implementation in java as well as the overall advantages, comparison with Generational ZGC.