[gclist] Purify Find new leaks performance / Real GC performance

[boehm.PARC@xerox.com]

"Purify is not a garbage collector.  It "solves" the problem of memory
leaks by pointing leaks out to you, which you in turn fix.  A real GC
solves memory leaks by automatically deallocating memory for you when
there's no more pointers to the memory in question."

That's technically correct.  But last I checked, Purify's leak detection
mechanism was essentially the same mechanism that could be used to implement a
basic conservative garbage collector.  It traces reachable memory, and looks
for unreachable objects that haven't been freed.  Our collector can be compiled
to perform the same sort of check on malloc/free code, but with less
sophisticated output.  Thus I think the original question about relative
performance makes sense, in spite of the fact that its primary intended use is
very different.

Hans
Standard disclaimer ...