I was just checking to see how much overhead I might pay using apply rather than destructuring a collection of args so I could call a function directly on them, when I found something I thought interesting:
TLDR: - apply is really slow - 2 orders of magnitude slower than a direct call - apply on an array, which I thought would be a direct way to the java varargs api is really slow - destructuring a list is two orders of magnitude slower than a vector - it is an order of magnitude faster to destructure a vector and may a direct call, than to use apply - etc openjdk full version "21.0.4+7" clojure 1.12.0 AMD Ryzen 9 5950X 16-Core Processor If I've made any silly mistakes, please point them out and I'll run these benchmarks again. If I am correct then there should be a lot of room to speed up apply and destructuring of lists ? Interested in peoples thoughts... Jules m3.repl> ;; let's have function that takes 4 args m3.repl> (defn foo [a b c d]) #'m3.repl/foo m3.repl> ;; let's try some direct calls m3.repl> (time (dotimes [_ 100000000] (foo 1 2 3 4))) "Elapsed time: 65.149019 msecs" nil m3.repl> (time (dotimes [_ 100000000] (foo 1 2 3 4))) "Elapsed time: 49.920188 msecs" nil m3.repl> (time (dotimes [_ 100000000] (foo 1 2 3 4))) "Elapsed time: 48.02132 msecs" nil m3.repl> ;; now lets try with a variety of collections via apply m3.repl> (def vargs [1 2 3 4]) #'m3.repl/vargs m3.repl> (def largs (list 1 2 3 4)) #'m3.repl/largs m3.repl> (def aargs (into-array Object [1 2 3 4])) #'m3.repl/aargs m3.repl> ;; a vector m3.repl> (time (dotimes [_ 100000000] (apply foo vargs))) "Elapsed time: 7166.218804 msecs" nil m3.repl> (time (dotimes [_ 100000000] (apply foo vargs))) "Elapsed time: 7167.766347 msecs" nil m3.repl> (time (dotimes [_ 100000000] (apply foo vargs))) "Elapsed time: 7154.58141 msecs" nil m3.repl> ;; a list m3.repl> (time (dotimes [_ 100000000] (apply foo largs))) "Elapsed time: 5657.564262 msecs" nil m3.repl> (time (dotimes [_ 100000000] (apply foo largs))) "Elapsed time: 5597.083287 msecs" nil m3.repl> (time (dotimes [_ 100000000] (apply foo largs))) "Elapsed time: 5638.361902 msecs" nil m3.repl> ;; and an array m3.repl> (time (dotimes [_ 100000000] (apply foo aargs))) "Elapsed time: 7954.757485 msecs" nil m3.repl> (time (dotimes [_ 100000000] (apply foo aargs))) "Elapsed time: 8125.750746 msecs" nil m3.repl> (time (dotimes [_ 100000000] (apply foo aargs))) "Elapsed time: 8151.5701 msecs" nil m3.repl> ;; is it faster to destructure first ? m3.repl> ;; a vector m3.repl> (time (dotimes [_ 100000000] (let [[a b c d] vargs] (foo a b c d)))) "Elapsed time: 904.68628 msecs" nil m3.repl> (time (dotimes [_ 100000000] (let [[a b c d] vargs] (foo a b c d)))) "Elapsed time: 902.818246 msecs" nil m3.repl> (time (dotimes [_ 100000000] (let [[a b c d] vargs] (foo a b c d)))) "Elapsed time: 905.498641 msecs" nil m3.repl> ;; a list m3.repl> (time (dotimes [_ 100000000] (let [[a b c d] largs] (foo a b c d)))) "Elapsed time: 30043.489179 msecs" nil m3.repl> (time (dotimes [_ 100000000] (let [[a b c d] largs] (foo a b c d)))) "Elapsed time: 30159.705918 msecs" nil m3.repl> (time (dotimes [_ 100000000] (let [[a b c d] largs] (foo a b c d)))) "Elapsed time: 30289.946966 msecs" nil m3.repl> ;; an array m3.repl> (time (dotimes [_ 100000000] (let [[a b c d] aargs] (foo a b c d)))) "Elapsed time: 14231.86232 msecs" nil m3.repl> (time (dotimes [_ 100000000] (let [[a b c d] aargs] (foo a b c d)))) "Elapsed time: 14081.057031 msecs" nil m3.repl> (time (dotimes [_ 100000000] (let [[a b c d] aargs] (foo a b c d)))) "Elapsed time: 14924.808985 msecs" nil m3.repl> ;; hmm... maybe destructuring the vector is taking a shortcut and not building a new collection whereas the others are m3.repl> (time (dotimes [_ 100000000] (let [[a b c d e] vargs] (foo a b c d)))) "Elapsed time: 1158.761312 msecs" nil m3.repl> (time (dotimes [_ 100000000] (let [[a b c d e] vargs] (foo a b c d)))) "Elapsed time: 570.542383 msecs" nil m3.repl> (time (dotimes [_ 100000000] (let [[a b c d e] vargs] (foo a b c d)))) "Elapsed time: 588.179669 msecs" nil m3.repl> (time (dotimes [_ 100000000] (let [[a b c d e] vargs] (foo a b c d)))) "Elapsed time: 589.489251 msecs" nil m3.repl> -- 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. To view this discussion on the web visit https://groups.google.com/d/msgid/clojure/d0e9472f-ca7d-4106-acc1-14082dd00aa5n%40googlegroups.com.
