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 <ritchie...@gmail.com> 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 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 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+unsubscr...@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. 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