"into" uses "reduce" under the hood, you probably need "fold" to have the computation to run on FJ:
(def a (time (r/foldcat (r/map #( Math/sin (* % %)) l))))) this runs more than 2x as fast on my macbook pro Las On Thu, Mar 20, 2014 at 10:34 AM, François Rey <fmj...@gmail.com> wrote: > On 20/03/14 04:03, Andy C wrote: > > So, the following test puzzles me. Not because it takes virtually the > same time (I know that Fork/Join is not cheap and memory is probably the > biggest bottleneck here). But because I do not get why map (as opposed to > r/ma) uses all 8 cores on my MacBookPro. All of them seem to be running > according to Activity Monitor at more less the same level. > > user=> (def l (into [] (range 60000000))) > #'user/l > user=> (time (def a (doall (map #(Math/sin (* % %)) l)))) > "Elapsed time: 19986.18 msecs" > > user=> (time (def a (doall (into [] (r/map #( Math/sin (* % %)) l))))) > "Elapsed time: 18980.583 msecs" > > I would also expect this code to run on a single CPU at any one time, > however process/thread scheduling can make this thread run on different > cores at different times. Depending on the sampling method the activity > monitor may display another picture of what you would expect. On my linux > machine, the cpu history graph shows it's using mostly one cpu at any one > time, but it's not always the same cpu. > I think the JVM uses all cores by default, and there's no standard way to > specify thread > affinity<http://stackoverflow.com/questions/2238272/java-thread-affinity> > . > > > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with > your first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > --- > You received this message because you are subscribed to the Google Groups > "Clojure" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clojure+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- László Török Checkout Lollyrewards.com <http://www.lollyrewards.com> - Giving credit, getting credit. Follow us on Twitter @lollyrewards <https://twitter.com/lollyrewards> Stay up to date on the latest offers by liking our Facebook page<https://www.facebook.com/lollyrewards> . -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
