Project proposal: Shenandoah

Roman Kennke roman at
Thu Feb 19 18:42:36 UTC 2015

I'd like to discuss the creation of the project Shenandoah with myself
*and/or* Christine Flood as initial lead and the Hotspot group as
sponsoring group.

It's aim is to implement a new garbage collector that reduces GC pause
times for applications that require really large heaps. Existing GCs
show pause times of several 100ms up to several seconds on heaps >
100GB. That is because they need to stop all Java threads for compacting
the heap. Shenandoah implements a new algorithm that allows to compact
heap while only stopping the Java threads briefly for root scanning, and
then evacuates the heap concurrently. This makes pause times unrelated
to the heap size and only proportional to the root set size.

Shenandoah has so far been developed as part of the IcedTea project:

It has usable implementations for OpenJDK9 and OpenJDK8.

Roman Kennke (me) is Principle Software Engineer at Red Hat, working on
Shenandoah since two years now. Before this, he worked on Thermostat,
and contributed to OpenJDK in several areas, most importantly the Zero
and Shark ports, graphics, and ports to embedded platforms.

Christine H. Flood is a prinicpal software engineer at Red Hat.  Most
recently she's been working on Shenandoah, before that she worked at
Oracle/Sun labs on the  Fortress programming language,  and on JVM
Scalability. She's one of the inventors of both the parallel GC
algorithm and G1.

Initial committers and reviewers would be me and Christine.

Could we both be project leads? Christine doesn't have an OpenJDK
idendity yet...

Best regards,

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