enerational GC algorithm described in
<A HREF="http://www.hpl.hp.com/personal/Hans_Boehm/gc/papers/pldi91.ps.Z">"Mostly Parallel Garbage Collection"</a>,
by Boehm, Demers, and Shenker.
<P>
The most significant modification is that
the collector always starts running in the allocating thread.
There is no separate garbage collector thread.  (If parallel GC is
enabled, helper threads may also be woken up.)
If an allocation attempt either requests a large object, or encounters
an empty small object free list, a