[Developers] Acre time limit(s)?

[Tom Morris]

What time limits does Acre have and on which operations?  I was hoping
that someone with some Acre knowledge would chime in on this
discussion http://www.freebase.com/view/guid/9202a8c04000641f800000000bdd7ac9
but I also just got the same error message from Typewriter (!) and
it's not terribly informative:

  Error in index
  Execution time limit exceeded
  at null:0

So what time limit was exceeded and what was it doing at the time?  A
stack trace or at least a line number would be useful information to
add to this.

I've also see circumstances where I see a naked Java stacktrace from
the thread killer as raw text instead of the formatted page, but the
stack trace is for the watchdog, not the application code being
executed.

Tom