problem with parallel foreach

[John Colvin via Digitalmars-d-learn]

On Thursday, 14 May 2015 at 10:46:53 UTC, Gerald Jansen wrote:
> John Colvin's improvements to my D program seem to have 
> resolved the problem.
> (http://forum.dlang.org/post/ydgmzhlspvvvrbeemrqf@forum.dlang.org
> and http://dpaste.dzfl.pl/114d5a6086b7).
>
> I have rerun my tests and now the picture is a bit different 
> (see tables below).
>
> In the middle table I have used gnu parallel in combination 
> with a slightly modified version of the D program which runs a 
> single trait (specified in argv[1]). This approach runs the 
> jobs as completely isolated processes, but at the extra cost of 
> re-reading the common data for each trait. The elapsed time is 
> very similar with the parallel foreach in the D program or 
> using gnu parallel (for this particular program and these data 
> run on this server...). I'm guessing the program is now 
> essentially limited by disk I/O, so this is about as good as it 
> gets.
>
> So, just to wrap up:
> - there is a nice speed improvement over Python program :-)
> - one needs to learn a fair bit to fully benefit from D's 
> potential
> - thanks for all the help!
>
> Gerald Jansen
>
>
> Jobs __ time for D parallel foreach w. JC mods____
> 1     4.71user  0.56system 0:05.28elapsed   99%CPU
> 2     6.59user  0.96system 0:05.48elapsed  137%CPU
> 4    11.45user  1.94system 0:07.24elapsed  184%CPU
> 8    20.30user  5.18system 0:13.16elapsed  193%CPU
> 16   68.48user 13.87system 0:27.21elapsed  302%CPU
> 27   99.66user 18.73system 0:42.34elapsed  279%CPU
>
> Jobs __ gnu parallel + D program for single job __
> 1     4.71user  0.56system 0:05.28elapsed   99%CPU as above
> 2     9.66user  1.28system 0:05.76elapsed  189%CPU
> 4    18.86user  3.85system 0:08.15elapsed  278%CPU
> 8    40.76user  7.53system 0:14.69elapsed  328%CPU
> 16  135.76user 20.68system 0:31.06elapsed  503%CPU
> 27  189.43user 28.26system 0:47.75elapsed  455%CPU
>
> Jobs _____ time for python version _____________
> 1    45.39user  1.52system 0:46.88elapsed  100%CPU
> 2    77.76user  2.42system 0:47.16elapsed  170%CPU
> 4   141.28user  4.37system 0:48.77elapsed  298%CPU
> 8   280.45user  8.80system 0:56.00elapsed  516%CPU
> 16  926.05user 20.48system 1:31.36elapsed 1036%CPU
> 27 1329.09user 27.18system 2:11.79elapsed 1029%CPU

Would it be OK if I showed some parts of this code as examples in 
my DConf talk in 2 weeks?