I've done a pass through most of the Clojure programs on the shootout
web site recently, making some of them faster, and choosing -Xmx
command line arguments when running them to keep the memory usage down
to a reasonable level -- not always the smallest heap size that works,
mind you -- just one that avoids exorbitantly large memory usage.
http://shootout.alioth.debian.org
The Clojure program for the "fasta" problem, with source code, AOT
compilation command, and execution command given on this web page:
http://shootout.alioth.debian.org/u32/program.php?test=fasta&lang=clojure&id=3
still takes about 6x to 8x more time than the best Java 6 -server
program here, depending upon which of the four machines it is run on:
http://shootout.alioth.debian.org/u32/program.php?test=fasta&lang=java&id=3
I'm sure the Clojure program can be made faster, e.g. by doing fewer
calls to write to the output file, with more bytes per call. Most of
the time seems to be file writing and generating random numbers in gen-
random!, at least on my systems where I've done testing and
profiling. I'm also seeing a fair amount of time spent in calls to
java.lang.Double.valueOf, according to the built-in profiler that
comes with the Hotspot JVM.
Note: The web site is Clojure 1.2 only right now, so don't expect a
tweaked-out program using things that only work in Clojure 1.3 to work
there yet. Other tips:
+ Test your program by comparing its output to the Java program with
the same command line args. The Java program isn't guaranteed to be
bug free, but it has been tested a fair amount.
+ If you decide to submit, please take some time to select a -Xmx max
heap size argument that gives a good tradeoff between low memory use
and not too much extra time spent doing GC because of it. I've got
some scripts to help automate finding such a value if you are
interested, and I'd even volunteer to run them for you if you send me
your program. Still, it is straightforward to do by hand, too -- no
rocket science involved.
You are of course free to work on any of the problems you wish, but I
just wanted to point out this one as being what I consider a bit
stubborn to squeeze down the run time.
Andy
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