My java was 1.8.0_05-b13. Upgraded it. Now it's around 9ms, close enough. Thanks a lot.
On Monday, June 15, 2015 at 4:59:57 PM UTC-5, Steven Yi wrote: > > I typed the array-max code and test in a REPL launched with "lein > repl" in a terminal. I did do that in the root of one of my projects > that had settings on to use 1.7.0 and to warn on reflection and > unchecked math. When I launched just now I have these versions > reported to the terminal: > > REPL-y 0.3.5, nREPL 0.2.8 > Clojure 1.7.0-beta3 > Java HotSpot(TM) 64-Bit Server VM 1.8.0_45-b14 > > > > On Mon, Jun 15, 2015 at 2:22 PM, Ritchie Cai <ritch...@gmail.com > <javascript:>> wrote: > > Ha, you are right. That really make things a lot faster now. All three > > different implementations now pretty much runs about the same speed, no > one > > is significantly faster or slower. Really appreciate your help. > > > > However, what really puzzles me at this point is that array-max call > speed. > > On all the systems I have tried, both Linux and Mac, both > clojure-1.7-beta3 > > and clojure-RC1, all using java 1.8. I get pretty much the same results, > all > > around 80ms no where near 4ms. Also I'm using lein repl with cider 0.8.2 > , > > the array-max is evaluated using cider-eval-defun-at-point (C-c C-c) > > function. > > > > Do you mind to give some more info on how you evaluated that function? I > > might be making some stupid mistake or something I'm not already know. > > > > On Thursday, June 11, 2015 at 11:20:42 AM UTC-5, Steven Yi wrote: > >> > >> I'm not sure why you'd see much slower results there. For reference, > >> I'm on a Core i7-2720-M (MacbookPro 8,1 13" early 2011), and was using > >> clojure-1.7-beta3. > >> > >> Also, I looked at the code you posted and I'm not so sure about your > >> assumption that Java arrays are slower: > >> > >> * in load-txt-image_array, you could probably type hint the data var > >> in the first let binding as ^doubles. With that, you should be able > >> to get rid of the type hinting throughout the rest of the function. > >> > >> * In your areduce code you're using a vector to carry the result, > >> which requires packing and unpacking, which ends up being somewhat > >> like auto-boxing. Using a loop-recur would allow you to carry over the > >> min and max separately between steps, something like: > >> > >> (let [len (alength data)] > >> (loop [i 0 my-min 0.0 my-max 0.0] > >> (if (< i len) > >> (let [v (aget data i)] > >> (recur (unchecked-inc i) (Math/min my-min v) (Math/max my-max > >> v))) > >> [my-min my-max]))) > >> > >> (could also use min and max instead of Math/min and Math/max) > >> > >> * In the "update pixel values" part of the function, you're using a > >> doseq with a range. That'd cause a sequence of boxed numbers of be > >> generated. Even though you have a ^double as a type hint, which will > >> get you out of the boxed math warning, there's still boxing going on > >> and you'll still first getting a boxed number and then have a cast to > >> primitive double. For example, if you use this function: > >> > >> user=> (defn a [] (doseq [i (range 50)] (println (+ ^double i 1.0)))) > >> > >> and use no.disassemble, you'll find byte code like this: > >> > >> 278 checkcast java.lang.Number [131] > >> 281 invokestatic > >> clojure.lang.RT.uncheckedDoubleCast(java.lang.Object) : double [135] > >> 284 dconst_1 > >> 285 invokestatic clojure.lang.Numbers.unchecked_add(double, > >> double) : double [141] > >> > >> I'd try using a loop-recur here as well instead of the doseq. > >> > >> As a sidenote, if haven't looked, you might give Prismatic's hiphip[1] > >> library a try. > >> > >> [1] - https://github.com/prismatic/hiphip > >> > >> On Thu, Jun 11, 2015 at 5:43 AM, Ritchie Cai <ritch...@gmail.com> > wrote: > >> > Yup. Reflection is issue, I needed type hint. > >> > However, on another note, I notice that in your first test case, your > >> > evaluation takes about 3 ms, but on my machine it takes 76 ms. I'm > >> > running a > >> > Xeon CPU at 3.5 GHZ, clojure-1.7-RC1. What could cause such a huge > >> > different > >> > timing? > >> > > >> > Thanks. > >> > > >> > > >> > On Wednesday, June 10, 2015 at 8:04:00 PM UTC-5, Steven Yi wrote: > >> >> > >> >> As mentioned by Colin and Andy, I would guess it would be some form > of > >> >> boxing and reflection going on. I tried the following: > >> >> > >> >> (defn array-max [^doubles arr] > >> >> > >> >> (let [len (alength arr)] > >> >> > >> >> (loop [m Double/NEGATIVE_INFINITY indx 0] > >> >> > >> >> (if (< indx len) > >> >> > >> >> (recur (max m (aget arr indx)) (unchecked-inc indx)) > >> >> > >> >> m)))) > >> >> > >> >> > >> >> user=> (let [vs (amap (double-array 1280000) idx ret (Math/random))] > >> >> > >> >> (time (array-max vs))) > >> >> > >> >> "Elapsed time: 3.719835 msecs" > >> >> > >> >> > >> >> To note, if you check out the source of areduce: > >> >> > >> >> user=> (source areduce) > >> >> > >> >> (defmacro areduce > >> >> > >> >> "Reduces an expression across an array a, using an index named > idx, > >> >> > >> >> and return value named ret, initialized to init, setting ret to > the > >> >> > >> >> evaluation of expr at each step, returning ret." > >> >> > >> >> {:added "1.0"} > >> >> > >> >> [a idx ret init expr] > >> >> > >> >> `(let [a# ~a] > >> >> > >> >> (loop [~idx 0 ~ret ~init] > >> >> > >> >> (if (< ~idx (alength a#)) > >> >> > >> >> (recur (unchecked-inc ~idx) ~expr) > >> >> > >> >> ~ret)))) > >> >> > >> >> > >> >> It's just a macro, and so typehinting is going to play a factor. > For > >> >> example, with areduce and a type hint on the array: > >> >> > >> >> > >> >> (defn array-max2 [^doubles arr] > >> >> > >> >> (areduce arr idx ret Double/NEGATIVE_INFINITY (max ret (aget arr > >> >> idx)))) > >> >> > >> >> user=> (let [vs (amap (double-array 1280000) idx ret (Math/random))] > >> >> (time > >> >> (array-max vs))) > >> >> > >> >> "Elapsed time: 3.314599 msecs" > >> >> > >> >> > >> >> But with no type hint on arr: > >> >> > >> >> > >> >> (defn array-max2 [arr] > >> >> > >> >> (areduce arr idx ret Double/NEGATIVE_INFINITY (max ret (aget arr > >> >> idx)))) > >> >> > >> >> > >> >> user=> (let [vs (amap (double-array 1280000) idx ret (Math/random))] > >> >> (time > >> >> (array-max2 vs))) > >> >> > >> >> "Elapsed time: 35612.919192 msecs" > >> >> > >> >> > >> >> Without a typehint on the arr argument, I also do get boxed math and > >> >> reflection warnings: > >> >> > >> >> > >> >> Reflection warning, > >> >> > >> >> > /private/var/folders/0k/xj_drd990xxf4q99n2bdknrc0000gn/T/form-init1595291808747030463.clj:2:3 > > > >> >> - call to static method alength on clojure.lang.RT can't be resolved > >> >> (argument types: unknown). > >> >> > >> >> Boxed math warning, > >> >> > >> >> > /private/var/folders/0k/xj_drd990xxf4q99n2bdknrc0000gn/T/form-init1595291808747030463.clj:2:3 > > > >> >> - call: public static boolean > >> >> clojure.lang.Numbers.lt(long,java.lang.Object). > >> >> > >> >> Reflection warning, > >> >> > >> >> > /private/var/folders/0k/xj_drd990xxf4q99n2bdknrc0000gn/T/form-init1595291808747030463.clj:2:58 > > > >> >> - call to static method aget on clojure.lang.RT can't be resolved > >> >> (argument > >> >> types: unknown, int). > >> >> > >> >> Boxed math warning, > >> >> > >> >> > /private/var/folders/0k/xj_drd990xxf4q99n2bdknrc0000gn/T/form-init1595291808747030463.clj:2:49 > > > >> >> - call: public static java.lang.Object > >> >> clojure.lang.Numbers.max(double,java.lang.Object). > >> >> > >> >> form-init1595291808747030463.clj:2 recur arg for primitive local: > ret > >> >> is > >> >> not matching primitive, had: Object, needed: double > >> >> > >> >> Auto-boxing loop arg: ret > >> >> > >> >> Reflection warning, > >> >> > >> >> > /private/var/folders/0k/xj_drd990xxf4q99n2bdknrc0000gn/T/form-init1595291808747030463.clj:2:3 > > > >> >> - call to static method alength on clojure.lang.RT can't be resolved > >> >> (argument types: unknown). > >> >> > >> >> Boxed math warning, > >> >> > >> >> > /private/var/folders/0k/xj_drd990xxf4q99n2bdknrc0000gn/T/form-init1595291808747030463.clj:2:3 > > > >> >> - call: public static boolean > >> >> clojure.lang.Numbers.lt(long,java.lang.Object). > >> >> > >> >> Reflection warning, > >> >> > >> >> > /private/var/folders/0k/xj_drd990xxf4q99n2bdknrc0000gn/T/form-init1595291808747030463.clj:2:58 > > > >> >> - call to static method aget on clojure.lang.RT can't be resolved > >> >> (argument > >> >> types: unknown, int). > >> >> > >> >> Boxed math warning, > >> >> > >> >> > /private/var/folders/0k/xj_drd990xxf4q99n2bdknrc0000gn/T/form-init1595291808747030463.clj:2:49 > > > >> >> - call: public static java.lang.Object > >> >> clojure.lang.Numbers.max(java.lang.Object,java.lang.Object). > >> >> > >> >> > >> >> > >> >> On Wednesday, June 10, 2015 at 4:07:09 PM UTC-4, Ritchie Cai wrote: > >> >>> > >> >>> I'm working on a java array of double with 1280000 elements. I need > >> >>> the > >> >>> max and min values of the array. So I initially tried areduce and > >> >>> loop, both > >> >>> gives runs around 20 seconds. But when try (apply max (vec array)) > I > >> >>> get > >> >>> result under 90 ms. > >> >>> Can anyone explain why there is such a big difference? > >> >>> Also if want to iterate large java array like this to do some other > >> >>> operations, e.g. convolution, what's the best way to go? Is there > >> >>> another > >> >>> fast way to iterate through array or do I need to convert array > into > >> >>> vector? > >> >>> > >> >>> Thanks > >> >>> Ritchie > >> >>> > >> > -- > >> > You received this message because you are subscribed to the Google > >> > Groups "Clojure" group. > >> > To post to this group, send email to clo...@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+u...@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 a topic in > the > >> > Google Groups "Clojure" group. > >> > To unsubscribe from this topic, visit > >> > https://groups.google.com/d/topic/clojure/Uh64-DaPYfc/unsubscribe. > >> > To unsubscribe from this group and all its topics, send an email to > >> > clojure+u...@googlegroups.com. > >> > For more options, visit https://groups.google.com/d/optout. > > > > -- > > You received this message because you are subscribed to the Google > > Groups "Clojure" group. > > To post to this group, send email to clo...@googlegroups.com > <javascript:> > > Note that posts from new members are moderated - please be patient with > your > > first post. > > To unsubscribe from this group, send email to > > clojure+u...@googlegroups.com <javascript:> > > For more options, visit this group at > > http://groups.google.com/group/clojure?hl=en > > --- > > You received this message because you are subscribed to a topic in the > > Google Groups "Clojure" group. > > To unsubscribe from this topic, visit > > https://groups.google.com/d/topic/clojure/Uh64-DaPYfc/unsubscribe. > > To unsubscribe from this group and all its topics, send an email to > > clojure+u...@googlegroups.com <javascript:>. > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Clojure" group. 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