clojure.core/time

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Type: macro Added: Clojure 1.0 Examples: 5 Runnable: 3

([expr])

Evaluates expr and prints the time it took. Returns the value of expr.

Examples

by gstamp on 2010-10-12 ▶

(time (Thread/sleep 100)) "Elapsed time: 100.284772 msecs" nil

by boxie on 2010-11-06 . May have evaluation errors. ▶

;when working with lazy seqs (time (doall (...)))

by Omer on 2012-05-29 . May have evaluation errors. ▶

;; Time how long it takes to write a string to a file 100 times (defn time-test [] (with-open [w (writer "test.txt" :append false)] (dotimes [_ 100] (.write w "I am being written to a file.")))) (time (time-test)) "Elapsed time: 19.596371 msecs"

by micrub on 2014-05-18 ▶

(time (Thread/sleep 1000)) "Elapsed time: 1000.267483 msecs" nil (with-out-str (time (Thread/sleep 1000))) "\"Elapsed time: 1010.12942 msecs\"\n"

by sFritsch09 on 2021-04-21 ▶

;;get elapsed time in seconds: (defmacro sectime [expr] `(let [start# (. System (currentTimeMillis)) ret# ~expr] (prn (str "Elapsed time: " (/ (double (- (. System (currentTimeMillis)) start#)) 1000.0) " secs")) ret#))

Note by mars0i

Because the Java JIT compiler compiles code differently after the code has been running for a bit of time, if you want to use time for benchmarking, you should at least "warm up" your code by running it several times, using the later time outputs as the ones that count. A better strategy is to use a benchmarking library such as Criterium, which will do the warmup for you, and much more.

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