Why do we have stack overflows?

John Meacham john at repetae.net
Thu May 3 19:59:58 EDT 2007

On Thu, May 03, 2007 at 05:40:24PM +0100, Adrian Hey wrote:
> Duncan Coutts wrote:
> >On Thu, 2007-05-03 at 16:24 +0100, Adrian Hey wrote:
> >>Hello Folks,
> >>
> >>Just wondering about this. Please understand I'm not asking why
> >>programs use a lot of stack sometimes, but specifically why is
> >>using a lot of stack (vs. using a lot of heap) generally regarded
> >>as "bad". Or at least it seems that way given that ghc run time
> >>makes distinction between the two and sets separate
> >>limits for them (default max stack size being relatively small
> >>whereas default max heap size in unlimited). So programs can
> >>fail with a stack overflow despite having bucket loads of heap
> >>available?
> >
> >Perhaps it's there to help people who write simple non-terminating
> >recursion. They'll get an error message fairly soon rather than using
> >all memory on the machine and invoking the wrath of the OOM killer.
> Hmm, I still don't see why a "stack leak" should be treated differently
> from "heap leak". They'll both kill your program in the end.

I believe it is because a stack cannot be garbage collected, and must be
traversed as roots for every garbage collection. I don't think there are
any issues with a huge stack per se, but it does not play nice with
garbage collection so may hurt your performance and memory usage in
unforeseen ways.


John Meacham - ⑆repetae.net⑆john⑈

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