Thanks for the replies guys. Both solutions outperform the original.
The one using unchecked operations is about 60x faster, which is the
kind of performance I was hoping for. It's good to see that Clojure
has the capacity to do things very quickly. I just need to learn all
the tricks to make it do so. I'm going to use this code as part of a
small agent demo I'm working on. Basically, it's going to take in work
units (MD5'd strings) and run brute force comparisons on them until a
match is found. I can fire up an agent per core and compare
performance numbers as the workload is parallelized. It's really
simple stuff but good for a concurrency beginner like me to explore
with.
Thanks,
Travis
On Jun 14, 10:00 am, tmountain <tinymount...@gmail.com> wrote:
> I've been playing around with rewriting some Java code in Clojure and
> did some simple benchmarking in the process. In this case, there's a
> huge disparity in the performance numbers between the two languages,
> and I'm wondering what the cause may be. The program rotates a string
> from "aaaa", "aaab", ..., "zzzz". The Java version takes 0.77 seconds
> to complete while the Clojure version takes 22 seconds. I've tried to
> make the scripts relatively isomorphic and have verified that they
> produce the same results. I'm pasting the source below.
>
> tra...@travis-ubuntu:/tmp% time clj base26.clj
> clj base26.clj 21.99s user 1.23s system 85% cpu 27.318 total
>
> tra...@travis-ubuntu:/tmp% time java Base26
> java Base26 0.77s user 0.04s system 78% cpu 1.029 total
>
> clojure version:
>
> (defn base26 [n]
> (let [seed-string "aaaa"
> s (new StringBuilder seed-string)]
> (loop [pos (- (count seed-string) 1)
> x n]
> (if (> x 0)
> (let [digit (+ (int \a) (mod x 26))]
> (. s setCharAt pos (char digit))
> (if (and (> pos 0) (> x 0))
> (recur (- pos 1) (/ x 26))))))
> (. s toString)))
>
> (doseq [i (range (Math/pow 26 4))]
> (base26 i))
>
> java version:
>
> import java.lang.StringBuilder;
>
> public class Base26 {
> public static void main(String[] args) {
> for (int i = 0; i < Math.pow(26, 4); i++) {
> Base26.base26(i);
> }
> }
>
> public static String base26(int num) {
> if (num < 0) {
> throw new IllegalArgumentException("Only positive numbers
> are supported");
> }
> StringBuilder s = new StringBuilder("aaaa");
> for (int pos = 3; pos >= 0 && num > 0 ; pos--) {
> char digit = (char) ('a' + num % 26);
> s.setCharAt(pos, digit);
> num = num / 26;
> }
> return s.toString();
> }
>
> }
>
> I've tried warn-on-reflection, and it didn't report anything.
>
> Thanks,
> Travis
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