Yup, I'm wrong. According to the profiler (visualvm), doseq/bit-shift-left is spending over 80% of its time in clojure.lang.Reflector.getMethods, but any other combination (e.g., dotimes/bsl or doseq/+) doesn't spend any time there at all. For 100k iterations, the doseq/bsl hits getMethods just over 100k times; the other combinations call it 18-27 times.
Something is definitely weird here. On Sep 30, 9:52 pm, Mark Engelberg <mark.engelb...@gmail.com> wrote: > On Thu, Sep 30, 2010 at 9:13 PM, ataggart <alex.tagg...@gmail.com> wrote: > > As with most microbenchmarks you're measuring the test more than the > > subject. In the above case the seq generation dominates. > > > Compare the following on my machine: > > user=> (time (doseq [x (range 100000)] (bit-shift-left x 1))) > > "Elapsed time: 3531.198 msecs" > > nil > > user=> (time (dotimes [x 100000] (bit-shift-left x 1))) > > "Elapsed time: 3.744 msecs" > > nil > > But if you replace the bit-shift-left operation with some other > arithmetic operation in the doseq expression, it is quite fast, thus > disproving your assertion that the slowdown is caused by the overhead > of doseq. Furthermore, as we've already discussed, type hinting the x > or removing the inline delcaration from bit-shift-left makes the > problem go away -- inside the doseq expression. > > So, if it is true that range produces objects and dotimes produces > primitive longs, then I believe that it is the odd interaction between > bit-shift-left's inlining and long objects (as opposed to primitives) > that is causing the disparity in your measurements, not something > inherent in the mechanism of doseq vs dotimes. -- 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
