I was going to say that testing JVM programs is notoriously tricky due to JIT warm up. Did you run that function enough to warm it before taking your timings?
This is why micro benchmark frameworks are popular. --Ashton Sent from my iPhone > On Dec 31, 2014, at 7:04 PM, Daniel <doubleagen...@gmail.com> wrote: > > The first thing that jumps out at me are the boxed numbers: 0N and 1N. I'm > guessing the Clojure implementation can produce a much larger result than the > python implementation can - so, apples to oranges. Probably unbox the > numbers and you get much more comparable speed. > > Also, you should definitely do two things when running speed comparisons: > > 1. Make sure the JVM flag -server is configured. > 2. Test with Criterium. (https://github.com/hugoduncan/criterium) > >> On Wednesday, December 31, 2014 2:03:03 PM UTC-6, Sakis K wrote: >> Hi, >> >> Clojure newbie here :) I'm reading "Programming Clojure" by Halloway and >> Bedra. In the book there is a lazy-seq example of the Fibonacci sequence: >> >> (defn lazy-seq-fibo >> ([] >> (concat [0 1] (lazy-seq-fibo 0N 1N))) >> ([a b] >> (let [n (+ a b)] >> (lazy-seq >> (cons n (lazy-seq-fibo b n)))))) >> >> >> I like the flexibility of this implementation but I am a bit sceptical about >> its performance: >> >> user=> (time (rem (nth (lazy-seq-fibo) 1000000) 1000)) >> "Elapsed time: 53552.014713 msecs" >> 875N >> >> >> >> Here's a Python implementation taken from >> http://en.literateprograms.org/Fibonacci_numbers_%28Python%29 >> >> def fib(n): >> a, b = 0, 1 >> for i in range(n): >> a, b = b, a + b >> return a >> >> if __name__ == '__main__': >> print(fib(1000000) % 1000) >> >> >> time python fib.py >> 875 >> >> real 0m16.609s >> user 0m16.475s >> sys 0m0.115s >> >> >> 53 vs 17 seconds is a big gap. Is there a way to achieve better performance >> in Clojure? Maybe the fact that I executed the code in the REPL or the Java >> version that I'm using matters: >> java -version >> java version "1.7.0_65" >> OpenJDK Runtime Environment (IcedTea 2.5.3) (7u71-2.5.3-0ubuntu1) >> OpenJDK 64-Bit Server VM (build 24.65-b04, mixed mode) > > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with your > first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > --- > You received this message because you are subscribed to the Google Groups > "Clojure" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clojure+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
