BLACKHOLE in heap profile

Tom Pledger
Sat, 19 Apr 2003 12:06:23 +1200

Hal Daume III writes:
 | My program which should use constant stack/heap is using a ton of
 | heap.  I profiled with -hd and the guy that's eating all the heap
 | is BLACKHOLE.  What does this mean?

AFAIK it's a way of detecting some infinite loops.  The BLACKHOLE
cells are the ones you're in the midst of evaluating, so if you try to
reenter any of them, you're provably going around in circles.

When the evaluation gets to the end of the chain of cells, and
retracts, they cease to be BLACKHOLEs.

As you go on to mention in your next message, this can happen when a
program turns out to be lazier than you expected.