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From "Xiao-Feng Li" <xiaofeng...@gmail.com>
Subject [DRLVM] DRLVM default GC was switched from GCv4.1 to GCv5
Date Sun, 22 Apr 2007 11:29:15 GMT
Hi, folks, I've made the switch of default DRLVM GC component from
GCv4.1 (gc_cc) to GCv5 (gc_gen) yesterday. This switch is only trial
for one week experiment. If things go well, it might be the default GC
from then on; otherwise, it will be switched back waiting for next
chance after JavaOne. (We do not know the switch result yet, since the
testing infrastructure looks to be resting in weekends.)

To make the switch is to bring Apache Harmony an advanced GC module
which has state-of-the-art design and implementation as a
stop-the-world GC. Basically, GCv5 is fully parallel in all phases of
garbage collection, with a couple of dynamic runtime adaptation
innovations to improve the throughput. GCv5 supports both generational
and non-generational mode. Experiments showed good performance
improvement over GCv4.1 for most workloads on parallel machines.

I have put a quick overview of Harmony GCv5 at
http://people.apache.org/~xli/docs/harmony_gcv5_overview.pdf . A basic
design principle of GCv5 is to be modular (or open). This is a big
difference from GCv4.1. Hope it could lay a good foundation for the
community to develop more sophisticated GC technologies. As I know,
there are two university projects already using GCv5 for their
Harmony-based research.

We would expect some regressions during the transition phase. Let's
promptly fix the bugs exposed, and try to make the switch smooth.

Thanks,
xiaofeng

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