I'm new and wanting to help!

[Tom Tromey]

Joel> I've just assumed that other VMs don't use copying collectors.

Actually I'm pretty sure that all the high-performance ones do.  But,
I do agree, whether this is a win depends on workload, at least AIUI.

Joel> One option would be to have support for IdentityHashMaps built
Joel> in to the GC, so that each instance is rehashed after GC.

In java the system hash code is guaranteed not to change over the
lifetime of the object, hence the cache-it-in-the-header approach.

Tom