Intro

Reviewing here about Concurrent GC’s and GC’s strategy, I saw about Shenandoah GC quite interesting topic. The phases are basically related to marking the regions.

Shenandoah GC

Basically, Shenandoah is about regional collection – if this sentence makes sense.  It has 9 phases but also 5 heuristics. The paper can be accessed here

Usage flag: XX:+UseShenandoahGC

The phases are enumerated below:

    Initial Mark       

   Concurrent Marking

   Final Mark

   Concurrent Cleanup

   Concurrent Evacuation

   Init Update Refs

   Concurrent Update References

   Final Update Refs

   Concurrent Cleanup

The heuristics can be used as:

-XX:ShenandoahGCHeuristics=<name>

And tells the GC how to actually start the mechanism. They are: adaptative, static, compact, passive and aggressive.

 

Youtube Video from Christine Flood

Reddit thread

Shenandoah Visualizer

It is possible to use the Shenandoah visualizer tool to understand more about it.

 

REFs

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