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Java / Java 17 Garbage Collection Interview Questions

What are the types of garbage collectors available in Java 17?

Java 17 ships with five usable collectors, plus one purely diagnostic collector, each selected with its own JVM flag:

CollectorFlagBest suited for
Serial GC-XX:+UseSerialGCSmall heaps, single-core machines
Parallel GC-XX:+UseParallelGCBatch jobs prioritizing raw throughput
G1 GC-XX:+UseG1GC (default)Balanced throughput and pause predictability
ZGC-XX:+UseZGCVery large heaps needing sub-10ms pauses
Shenandoah-XX:+UseShenandoahGCLow pause times independent of heap size
Epsilon-XX:+UseEpsilonGCNo-op collector for perf testing, never reclaims

Note that CMS (Concurrent Mark Sweep) is not in this list - it was deprecated in JDK 9 and fully removed in JDK 14, so it is not an option on Java 17.

Java 17's default garbage collector is:
Epsilon GC is best described as:

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