On Fri, 01 Mar 2013 19:19:35 -0500, cvk012c
<[email protected]> wrote:
On Friday, 1 March 2013 at 21:52:13 UTC, bearophile wrote:
cvk012c:
I think that similar Perl and Java scripts will outperform D easily.
Thanks Andrei and simendsjo for a quick response though.
Why don't you write a Java version? It takes only few minutes, and you
will have one more data point.
You are right. Why not. But instead of using Java split() method I used
combination of indexOf() and substring() methods to do the same job. The
reason: Java split method implemented as a regular expression which will
be unfair to compare to D splitter. Again, I created a similar D version
of the script, compiled it with all suggested options: -release -O
-inline -noboundscheck and this time D version is more then twice slower
than Java: 8.4 seconds vs 4.
D experts, please, take a look at my code and tell me what is wrong with
it.
Try my hand-written version (elsewhere in thread). I think it can be done
better too (use pointers instead of arrays).
The issue is a combination of the fact that:
1. splitter is designed for any range, not just strings. Not an excuse
really, but a string-specific version could be written that does better
(clearly).
2. dmd is not always the best optimizer. I saw one other person who said
using a different d compiler resulted in a quicker time.
3. Any time you are looping 10 million times, small insignificant
differences will be magnified.
Note one other thing -- Be VERY wary of test cases that are fully-visible
at compile time. Very smart compilers are known to reduce your code to
something that isn't realistic. I remember seeing a similar comparison
not too long ago where one wondered why g++ was so much faster (0.09
seconds or something) than D (4 or more seconds). Turns out, the g++
compiler optimized out his ENTIRE program :).
You may want to read in the "message" string at runtime to avoid such
issues.
-Steve
