On Apr 26, 2013, at 12:41 PM, Claudio Freire <klaussfre...@gmail.com> wrote:
> On Fri, Apr 26, 2013 at 1:35 PM, Michael Bayer <mike...@zzzcomputing.com> > wrote: >>> >>> Um... a tad OT, but looking at that code, there's lots of >>> opportunities for optimization. >>> >>> I'll have to profile a bit and let you know. >> >> are you referring to sqlalchemy/orm/loading.py ? I'd be pretty impressed >> if you can find significant optimizations there which don't break usage >> contracts. I've spent years poring over profiles and squeezing every >> function call possible out of that system, sometimes producing entirely new >> approaches that I just had to throw out since they didn't work. It has >> been rewritten many times. Some background on the approach is at >> http://www.aosabook.org/en/sqlalchemy.html, "20.7. Query and Loading >> Behavior". > > > I know... I'm talking micro-optimization. Pre-binding globals in tight > loops, for instance, like: > > def filter_fn(x, tuple=tuple, zip=zip): > return tuple(...) > > This is of course only worth it for really really hot loops. That's > why I'm profiling. Maybe it's been done already for all the hottest > loops. > > Then there's the possibility to replace some list comprehensions with > itertools, which besides not building a temp list, would also run > entirely in C. This also only makes a difference only on very tight, > builtin-laden loops. > > I have an app here that really stresses that part of the ORM, so I can > profile rather easily. In previous profiles, I remember seeing > Query.instances near the top, and all the optimizations I mentioned > above could be applied there, if they make any difference I'll tell. the real bottleneck in loading is the loading.instances() function. I have tried for years to reduce overhead in it. Writing it in C would be best, but then again Pypy aims to solve the problem of FN overhead, pre-binding, and such. I don't want to work against Pypy too much. -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
