[Python-Dev] PEP 0424: A method for exposing a length hint

[Antoine Pitrou]

On Mon, 16 Jul 2012 02:00:58 +1000
Chris Angelico <rosuav at gmail.com> wrote:
> On Mon, Jul 16, 2012 at 1:55 AM, Steven D'Aprano <steve at pearwood.info> wrote:
> > (I expect the difference in behaviour is due to the default ulimit under
> > Debian/Mint and RedHat/Fedora systems.)
> 
> Possibly also virtual memory settings. Allocating gobs of memory with
> a huge page file slows everything down without raising an error.
> 
> And since it's possible to have non-infinite but ridiculous-sized
> iterators, I'd not bother putting too much effort into protecting
> infinite iterators - although the "huge but not infinite" case is,
> admittedly, rather rarer than either "reasonable-sized" or "actually
> infinite".

In the real world, I'm sure "huge but not infinite" is much more
frequent than "actually infinite". Trying to list() an infinite
iterator is a programming error, so it shouldn't end up in production
code. However, data that grows bigger than expected (or that gets
disposed of too late) is quite a common thing.

<hint>
When hg.python.org died of OOM two weeks ago, it wasn't because of an
infinite iterator:
http://mail.python.org/pipermail/python-committers/2012-July/002084.html
</hint>

Regards

Antoine.


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