[Python-Dev] Issue 14417: consequences of new dict runtime error (original) (raw)

Guido van Rossum guido at python.org
Sat Mar 31 23:26:25 CEST 2012

Try reducing sys.setcheckinterval().

--Guido van Rossum (sent from Android phone) On Mar 31, 2012 10:45 AM, "R. David Murray" <rdmurray at bitdance.com> wrote:

On Sun, 01 Apr 2012 03:03:13 +1000, Nick Coghlan <ncoghlan at gmail.com> wrote: > On Sun, Apr 1, 2012 at 2:09 AM, Guido van Rossum <guido at python.org> wrote: > > Here's a different puzzle. Has anyone written a demo yet that provokes > > this RuntimeError, without cheating? (Cheating would be to mutate the > > dict from inside the eq or hash method.) If you're serious > > about revisiting this, I'd like to see at least one example of a > > program that is broken by the change. Otherwise I think the status quo > > in the 3.3 repo should prevail -- I don't want to be stymied by > > superstition. > > I attached an attempt to deliberately break the new behaviour to the > tracker issue. It isn't actually breaking for me, so I'd like other > folks to look at it to see if I missed something in my implementation, > of if it's just genuinely that hard to induce the necessary bad timing > of a preemptive thread switch.

Thanks, Nick. It looks reasonable to me, but I've only given it a quick look so far (I'll try to think about it more deeply later today). If it is indeed hard to provoke, then I'm fine with leaving the RuntimeError as a signal that the application needs to add some locking. My concern was that we'd have working production code that would start breaking. If it takes a lot of threads or a lot of mutation to trigger it, then it is going to be a lot less likely to happen anyway, since such programs are going to be much more careful about locking anyway. --David -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20120331/1d087f4e/attachment.html>

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