Switch to a pthread mutex instead of the spin lock.  This improves performance significantly under heavy contention.  I see a factor 2 speedup on 8 core Mac Pro, running 16 threads.  Previously, the only way I was beating the system allocator in performance was by not running the collector thread, but 16 threads pushed it over the high-water mark.
Switch to a pthread mutex instead of the spin lock.  This improves
performance significantly under heavy contention.  I see a
factor 2 speedup on 8 core Mac Pro, running 16 threads.  Previously,
the only way I was beating the system allocator in performance was
by not running the collector thread, but 16 threads pushed it over
the high-water mark.

amaxwell/fileview,bitemyapp/fileview,bitemyapp/fileview