[erlang-questions] Parallel Shootout & a style question
Tue Sep 2 02:33:47 CEST 2008
First, I don't think it's been mentioned here, but the language
benchmarks shootout finally got some multi-core hardware!
At the moment, though, there are almost no submissions of parallelized
code, so the results are about the same as the existing hardware.
I figured (slightly spurred on by the Haskell community) that we
should try to submit some modified versions that actually use the
multiple cores. So, for example, I made a slight change to the binary
trees code and got a nearly 2x speedup on my 2-core machine. In doing
so, I did run into one of those little things that I've never really
known the preferred approach for. My modified function looks like this:
depthLoop(D,M) when D > M -> ok;
Self = self(),
N = 1 bsl (M-D + ?Min),
io:fwrite("~w\t trees of depth ~w\t check: ~w~n",
[ 2*N, D, sumLoop(N,D,0) ]),
Self ! done
receive done -> done end.
parallelizing would only require the addition of the spawn, except
that if I do that, the function finishes executing and the program
exits before most of the processes run at all. So, I need to add the
call to self(), the send, and the receive in order to prevent
premature termination. So, what I'm wondering is, is there a better
idiom for achieving this goal?
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