[erlang-questions] Parallel Shootout & a style question

Ulf Wiger (TN/EAB) <>
Tue Sep 2 10:21:25 CEST 2008


Mats Cronqvist skrev:
> Gleb Peregud wrote:
>> Maybe it is good idea to include something like 
>> http://code.google.com/p/plists/ into Erlang/OTP? It will probably 
>> introduce more less tuned software created by developers, but it
>> will make programming multi-core systems much more easier and fun
>> for beginners.
 >
> in an ideal world, all the basic OTP libs should be rewritten to be 
> parallel. who gives an expletive if it's 10% slower on a single core
>  machine?

Radical, but you have a point.

Before Robert reminds me, I might as well admit that I
scolded him severely for rewriting lists:map/2 as a
list comprehension, back in those days when LCs were
slower. Sorry Robert (but I was right ;-)

I am pretty sure that 10% means a lot to some people
out there.

However, if the library functions perform a lightweight
check and pick the parallel version only if SMP is enabled,
we're not talking 10%.

erlang:system_info(smp_support) -> boolean()

seems to hit the spot.

Perhaps an alias, like smp() -> boolean() could ease
the strain on our eyes and prevent carpal-tunnel
syndrome:

map(F, L) when smp() -> pmap(F, L);
map(F, L) ->
   [F(X) || X <- L].


BR,
Ulf W



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