GC "Heisenberg" problem in latest CVS bootstrap?

[Tim Olson]

When I did the second-level bootstrap process on the most recent code 
(build a vm & image, then use those to build again), I find that the 
second-level build gets slower and slower,  hanging when parsing 
numeric.slate and dying with a segmentation violation.  Using the Shark 
performance tool I see that it is spending nearly all of its time in GC 
(markAndPushSlotsOf, findNextFree, pinCards), and less than 1% of its 
time in interpret, just before it dies.

However, if I add a debug print to lexer.slate to show the line number, 
the second-level bootstrap process completes successfully.  Seems like 
a Heisenberg somehow related to GC.

Is anyone else seeing issues similar to this?

	-- tim