How slow is GNU Parallel

[Ole Tange]

Back in the early days of GNU Parallel a job could be processed within
just 3 ms.

These days there are many more checks and much more flexibility has
been added - and that costs.

So I was curious how the performance of GNU Parallel has changed over time.

www.gnu.org/s/parallel/process-time-j8-1.7ghz-300-1000.pdf

This was measured on my 4 hyperthreaded cpus (= 8 "cores") forced to
run 1.7GHz, so the timings may be lower if you have a faster cpu or if
you do not use hyperthreading.

So there are a couple of increases that stand out:

* 20101122 included a complete rewrite to object orientation. Without
this rewrite a lot of the following development would have been much
harder.
* 20140722 made it possible to use Perl expressions as replacement
strings. Without this the elegant '--rpl' would not have been
possible.

All in all you should expect around 10 ms for starting a job locally
using GNU Parallel.


/Ole