Explain JVM Memory Architecture and the Evolution of Java Garbage Collectors (G1, ZGC, Parallel).

Quick Revision Summary

JVM separates heap into Young and Old generations based on weak generational hypothesis. G1 balances throughput with bounded pause times, while ZGC achieves sub-millisecond latency.

Interactive Practice Mode

Formulate your thoughts or take notes before revealing the model solution.

Model Answer & Deep-Dive Explanation

The JVM Memory Structure is divided into:

Heap Memory: Shared among all threads, storing object instances. Divided into Young Generation (Eden space, Survivor spaces S0/S1) and Old Generation (Tenured).
Metaspace (Native Memory): Stores class metadata, bytecode, and method signatures (replaced PermGen in Java 8).
JVM Stacks: Thread-private, stores stack frames (local variables, operand stack).

Garbage Collector Evolution:

Parallel GC: Multi-threaded collector focused on maximum application throughput; incurs Stop-The-World (STW) pauses.
G1 GC (Garbage-First): Default since Java 9. Divides heap into thousands of equal-sized regions. Prioritizes collecting regions with the most garbage to meet a target maximum pause time (-XX:MaxGCPauseMillis).
ZGC (Z Garbage Collector): Low-latency concurrent GC designed for multi-terabyte heaps with pause times consistently below 1 millisecond.

Interviewer Evaluation Points & Scoring Rubric

1 1. Outlines Heap vs Metaspace vs Stack. 2. Explains Young/Old generation rationale. 3. Compares Parallel, G1, and ultra-low latency ZGC.

Previous: What is the difference between String, StringBuilder, and StringBuffer in Java? All Java Next: How do == and equals differ when comparing Java strings?

Explain JVM Memory Architecture and the Evolution of Java Garbage Collectors (G1, ZGC, Parallel).

Interviewer Evaluation Points & Scoring Rubric

Related Questions in Java

Report Question or Answer