Can JVM Reduce GC Pauses to Sub 1ms Like Go?

The Go programming language boasts low GC pauses, typically below 100 microseconds. However, the Java Virtual Machine (JVM) has faced challenges in achieving similar performance.

Architectural Constraints

Historically, architectural differences between Go and Java have influenced GC pause times.

• Go's Non-Compacting Collector: Go's GC does not compact memory, allowing for quick processing.
• Java's Generational and Compacting Collector: JVM GCs typically use generational and compacting algorithms, which require additional time for heap reorganization.

Current Developments

However, recent advancements in JVM GCs address these constraints:

• Azul's Pauseless Collector: Azul offers a proprietary collector that achieves sub-millisecond pause times even with large heaps.
• OpenJDK's Shenandoah and ZGC: These collectors utilize data structures and techniques that reduce pause times significantly.
• IBM's Metronome: Metronome aims to achieve microsecond-level pause times by decoupling GC from mutator threads.

Tradeoffs

While JVM GCs can now approach Go's GC pause times, they often involve tradeoffs:

• Increased Complexity: The aforementioned collectors introduce higher complexity to the GC implementation.
• Lower Throughput: Non-compacting collectors may sacrifice throughput compared to their compacting counterparts.
• Memory Fragmentation: Go's non-compacting collector can result in memory fragmentation, potentially affecting performance over time.

Conclusion

While architectural constraints initially inhibited the JVM from achieving Go-like GC pauses, recent developments have bridged this gap. JVM GCs now leverage techniques that substantially reduce pause times, although they may differ in their performance characteristics and tradeoffs compared to Go's collector.