"Harmony already has a concurrent GC (called Tick, with three concurrent GC algorithms). It runs well with standard benchmarks. The only remaining unfinished feature is WeakReference support . Weakly referenced object (i.e., referent) is accessed through get() interface. That means, get() operation can make a weakly reachable referent strongly reachable. During concurrent collection, the system must monitor the get() operation to catch this change of reachability, otherwise the referent could be reclaimed. This project also includes to integrate the WeakReference processing with Finalization process. Other optimizations in Tick are also desirable, such as to reduce the amount of floating garbage. "
Thanks, xiaofeng -- http://people.apache.org/~xli
