On Sat, Feb 11, 2017 at 08:15:08PM +0000, Adam Johnson wrote: > I can see the advantage from an operational perspective with files matching > byte-for-byte. I know many API's do the same with sorting the keys in their > JSON output for the same reason. > I should think the performance impact isn't too great, but would be nice to > see some benchmarking to prove it's not disastrous.
I did a small benchmark, and as expected, the impact is really small. Without the pull-request, generating an Atom feed with 100 medium sized entries takes ~ 0.01 s on consumer hardware. The sorting and creation of OrderedDicts increases the runtime by ~ 27 %. Note that this benchmark generates the same feed several times in a row because the absolute runtime is so small. See https://gist.github.com/gsauthof/e2787adc7e9a46811dcb6aff2054110c for details. It pays off to only sort+create OrderedDict if there are attributes, e.g.: def startElement(self, name, attrs): xs = collections.OrderedDict(sorted(attrs.items())) if attrs else attrs super().startElement(name, xs) That version yields an ~ 18 % runtime increase. We can get down to ~ 7 % runtime increase if we - in feedgenerator.py - replace the attribute dictionaries with a simple wrapper around a list that provides the items() method, e.g.: class Atts: def __init__(self, items): self.xs = items def items(self): return self.xs And then add the elements with attributes like this: handler.addQuickElement("atom:link", None, Atts([("rel", "self"), ("href", self.feed['feed_url'])])) But IMHO, this would be a premature optimization that just obfuscates the feedgenerator code. Even the conditional sorting is hardly necessary outside of microbenchmarking scenarios. Best regards Georg -- 'One must not put a loaded rifle on the stage if no one is thinking of firing it.' ( Anton Chekhov, 1889 ) -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-developers+unsubscr...@googlegroups.com. To post to this group, send email to django-developers@googlegroups.com. Visit this group at https://groups.google.com/group/django-developers. To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/20170212162710.GA12316%40dell12.lru.li. For more options, visit https://groups.google.com/d/optout.
