Forcing small bits of computation to be done in parallel using the tools
Clojure and the JVM have at hand, e.g. pmap, future, etc., which rely on
creating JVM Thread objects, tends to slow things down rather than speed
things up, because the extra overhead of creating threads and waiting for
them to finish is higher than the cost of sequentially doing the small bits
of computation.
If you want to force parallelism in your example anyway, to compare the
most-likely-slower-performance against what you have now, you can try this:
(let [val (Math/sqrt i)
a1 (future (Math/pow val 2))
a2 (future (* val val))
diff (Math/abs (- @a1 @a2))]
Andy
On Thu, Apr 10, 2014 at 7:35 AM, Cecil Westerhof <cldwester...@gmail.com>wrote:
> I have the following in my code:
> (let [val (Math/sqrt i)
> diff (Math/abs (- (Math/pow val 2) (* val val)))]
>
> I expect that calculating the difference is the most expensive part of my
> code. I understood that Clojure is very good in parallellisation. How would
> I let (Math/pow val 2) and (* val val) be calculated in parallel?
>
> --
> Cecil Westerhof
>
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