You have to be very careful with microbenchmarks like this. I recommend
writing less trivial benchmarks. For example
http://github.com/clojure/test.benchmark/blob/master/src/main/clojure/alioth/spectral_norm.clj
This code demonstrates performance on par with plain Java. There are many
other similar examples in the test.benchark project.
David
On Thu, Apr 25, 2013 at 9:44 AM, Alice <dofflt...@gmail.com> wrote:
> Primitive hinted funtions seem to be not an exception.
>
> (defn my-inc ^long [^long l] (inc l))
>
> (defn f1 [^long l] (inc l))
> (defn f2 [^long l] (my-inc l))
>
> (time (dotimes [n 100000000] (f1 1)))
> (time (dotimes [n 100000000] (f1 1)))
> (time (dotimes [n 100000000] (f1 1)))
> (time (dotimes [n 100000000] (f2 1)))
> (time (dotimes [n 100000000] (f2 1)))
> (time (dotimes [n 100000000] (f2 1)))
>
> "Elapsed time: 68.683431 msecs"
> "Elapsed time: 68.964182 msecs"
> "Elapsed time: 68.105047 msecs"
> "Elapsed time: 108.576746 msecs"
> "Elapsed time: 100.992193 msecs"
> "Elapsed time: 100.945511 msecs"
>
> On Apr 25, 10:32 pm, David Nolen <dnolen.li...@gmail.com> wrote:
> > primitive hinted fns will get inlined. You can also play the same kinds
> of
> > games that Clojure does with definterface+deftype and fns that declare
> > :inline metadata.
> >
> > If you don't want to learn the subtleties of Clojure performance tuning
> > then you can always write your performance critical bits in Java and call
> > into it. Some folks, like the people at Prismatic, seem to be doing
> pretty
> > well writing all their performance critical code in Clojure, but they've
> > built some tools to avoid the various potential pitfalls.
> >
> >
> >
> >
> >
> >
> >
> > On Thu, Apr 25, 2013 at 9:19 AM, Alice <dofflt...@gmail.com> wrote:
> > > I create many small methods in java without worrying about the
> > > performance since it's usually the target of inline optimization. For
> > > example,
> >
> > > public class Foo {
> > > public static long inc(long l) {
> > > return ++l;
> > > }
> >
> > > public static long f1() {
> > > long l = 0;
> > > for (int i=0; i < 1000000000; i++) {
> > > l++;
> > > }
> > > return l;
> > > }
> >
> > > public static long f2() {
> > > long l = 0;
> > > for (int i=0; i < 1000000000; i++) {
> > > l = inc(l);
> > > }
> > > return l;
> > > }
> > > }
> >
> > > (time (Foo/f1))
> > > (time (Foo/f1))
> > > (time (Foo/f1))
> > > (time (Foo/f2))
> > > (time (Foo/f2))
> > > (time (Foo/f2))
> >
> > > "Elapsed time: 23.309532 msecs"
> > > "Elapsed time: 23.333039 msecs"
> > > "Elapsed time: 21.714753 msecs"
> > > "Elapsed time: 22.943366 msecs"
> > > "Elapsed time: 21.612783 msecs"
> > > "Elapsed time: 21.71376 msecs"
> >
> > > But clojure funtions seem to be never get inlined.
> >
> > > (def obj (Object.))
> >
> > > (defn getObj [] obj)
> >
> > > (defn f1 [] obj)
> > > (defn f2 [] (getObj))
> >
> > > (time (dotimes [n 100000000] (f1)))
> > > (time (dotimes [n 100000000] (f1)))
> > > (time (dotimes [n 100000000] (f1)))
> > > (time (dotimes [n 100000000] (f2)))
> > > (time (dotimes [n 100000000] (f2)))
> > > (time (dotimes [n 100000000] (f2)))
> >
> > > "Elapsed time: 67.758744 msecs"
> > > "Elapsed time: 68.555306 msecs"
> > > "Elapsed time: 68.725147 msecs"
> > > "Elapsed time: 104.810459 msecs"
> > > "Elapsed time: 103.273618 msecs"
> > > "Elapsed time: 103.374595 msecs"
> >
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