advanced~4h
Garbage Collection Fundamentals
What 'Java is a managed language' actually means mechanically: how the JVM proves an object is truly unreachable, why the heap is split into generations built around the observation that most objects die young, and a tour of the major collectors -- Serial, Parallel, G1, ZGC and Shenandoah -- and the specific problem each one exists to solve.
Learning objectives
- Explain reachability and why it, not reference counting, is how the JVM decides an object is garbage
- Explain the generational hypothesis and why it justifies splitting the heap into Young and Old generations
- Distinguish a minor GC from a major/full GC and explain why their costs differ so much
- Explain what a stop-the-world pause is and why every collector has to cause one at some point
- Describe, at a conceptual level, what problem each of Serial, Parallel, G1, ZGC and Shenandoed collector solves
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Garbage Collection Fundamentals