onment variable).  If only a single processor is detected,
parallel marking is disabled.
<P>
Note that setting GC_NPROCS to 1 also causes some lock acquisitions inside
the collector to immediately yield the processor instead of busy waiting
first.  In the case of a multiprocessor and a client with multiple
simultaneously runnable threads, this may have disastrous performance
consequences (e.g. a factor of 10 slowdown). 
<H2>Performance</h2>
We conducted some simple experiments with a version of
<A HREF="gc_