* Steven D'Aprano (08 Aug 2009 03:29:43 GMT) > On Fri, 07 Aug 2009 17:13:07 +0200, Thorsten Kampe wrote: > > One guy claims he has times between 2.7 and 5.7 seconds when > > benchmarking more or less randomly generated "one million different > > lines". That *is* *exactly* nothing. > > We agree that in the grand scheme of things, a difference of 2.7 seconds > versus 5.7 seconds is a trivial difference if your entire program takes > (say) 8 minutes to run. You won't even notice it.
Exactly. > But why assume that the program takes 8 minutes to run? Perhaps it takes > 8 seconds to run, and 6 seconds of that is the decoding. Then halving > that reduces the total runtime from 8 seconds to 5, which is a noticeable > speed increase to the user, and significant if you then run that program > tens of thousands of times. Exactly. That's why it doesn't make sense to benchmark decode()/unicode () isolated - meaning out of the context of your actual program. > By all means, reminding people that pre-mature optimization is a > waste of time, but it's possible to take that attitude too far to Planet > Bizarro. At the point that you start insisting, and emphasising, that a > three second time difference is "*exactly*" zero, Exactly. Because it was not generated in a real world use case but by running a simple loop one millions times. Why one million times? Because by running it "only" one hundred thousand times the difference would have seen even less relevant. > it seems to me that this is about you winning rather than you giving > good advice. I already gave good advice: 1. don't benchmark 2. don't benchmark until you have an actual performance issue 3. if you benchmark then the whole application and not single commands It's really easy: Michael has working code. With that he can easily write two versions - one that uses decode() and one that uses unicode(). He can benchmark these with some real world input he often uses by running it a hundred or a thousand times (even a million if he likes). Then he can compare the results. I doubt that there will be any noticeable difference. Thorsten -- http://mail.python.org/mailman/listinfo/python-list
