http://dev.clojure.org/jira This file is an XML representation of an issue en-us 4.4 649 25-07-2011 http://dev.clojure.org/jira/browse/CLJ-1005 Clojure <p>The attached patch changes zipmap to use a transient map internally. The definition is also moved so that it resides below that of #'transient. The original definition is commented out (like that of #'into).</p> CLJ-1005

Use transient map in zipmap

Enhancement Major Open Unresolved Aaron Bedra Michał Marczyk Wed, 30 May 2012 02:55:43 -0500 Thu, 11 Apr 2013 18:19:28 -0500 Release 1.6 Release 1.6 0 0 <p>Why is the old implementation left and commented out? If we are going to move to a new implementation, the old one should be removed.</p> <p>As mentioned in the ticket description, the previously attached patch follows the pattern of into whose non-transient-enabled definition is left in core.clj with a #_ in front &#8211; I wasn't sure if that's something desirable in all cases.</p> <p>Here's a new patch with the old impl removed.</p> <p>Thanks for the updated patch, Michal. Sorry to raise such a minor issue, but would you mind using a different name for the updated patch? I know JIRA can handle multiple attached files with the same name, but my prescreening code isn't quite that talented yet, and it can lead to confusion when discussing patches.</p> <p>Thanks for the heads-up, Andy! I've reattached the new patch under a new name.</p> <p>Presumptuously changing Approval from Incomplete back to None after the Michal's updated patch was added, addressing the reason the ticket was marked incomplete.</p> <p>The patch looks good and applies cleanly. Are there additional tests that we should run to verify that this is providing the improvement we think it is. Also, is there a discussion somewhere that started this ticket? There isn't a lot of context here.</p> <p>Hi Aaron,</p> <p>Thanks for looking into this!</p> <p>From what I've been able to observe, this change hugely improves <tt>zipmap</tt> times for large maps. For small maps, there is a small improvement. Here are two basic Criterium benchmarks (<tt>transient-zipmap</tt> defined at the REPL as in the patch):</p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre>;;; large map user=&gt; (def xs (range 16384)) #'user/xs user=&gt; (last xs) 16383 user=&gt; (c/bench (zipmap xs xs)) Evaluation count : 13920 in 60 samples of 232 calls. Execution time mean : 4.329635 ms Execution time std-deviation : 77.791989 us Execution time lower quantile : 4.215050 ms ( 2.5%) Execution time upper quantile : 4.494120 ms (97.5%) nil user=&gt; (c/bench (transient-zipmap xs xs)) Evaluation count : 21180 in 60 samples of 353 calls. Execution time mean : 2.818339 ms Execution time std-deviation : 110.751493 us Execution time lower quantile : 2.618971 ms ( 2.5%) Execution time upper quantile : 3.025812 ms (97.5%) Found 2 outliers in 60 samples (3.3333 %) low-severe 2 (3.3333 %) Variance from outliers : 25.4675 % Variance is moderately inflated by outliers nil ;;; small map user=&gt; (def ys (range 16)) #'user/ys user=&gt; (last ys) 15 user=&gt; (c/bench (zipmap ys ys)) Evaluation count : 16639020 in 60 samples of 277317 calls. Execution time mean : 3.803683 us Execution time std-deviation : 88.431220 ns Execution time lower quantile : 3.638146 us ( 2.5%) Execution time upper quantile : 3.935160 us (97.5%) nil user=&gt; (c/bench (transient-zipmap ys ys)) Evaluation count : 18536880 in 60 samples of 308948 calls. Execution time mean : 3.412992 us Execution time std-deviation : 81.338284 ns Execution time lower quantile : 3.303888 us ( 2.5%) Execution time upper quantile : 3.545549 us (97.5%) nil </pre> </div></div> <p>Clearly the semantics are preserved provided transients satisfy their contract.</p> <p>I think I might not have started a ggroup thread for this, sorry.</p> Global Rank Patch Code