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https://issues.apache.org/jira/browse/TAP5-2332?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14001980#comment-14001980
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Michael Mikhulya commented on TAP5-2332:
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As I know String concatenation internally uses StringBuilder, so here shouldn't
be big difference in performance between these two ways. InternalUtils.concat
should be slower because it contains extra method call and adds creation of
array to pass var args, but probably all of it can me inlined by HotSpot.
I will create JMH test and provide numbers tomorrow.
But is there a reason to hide string concatenation? String concatenation
produce less code in comparison with InternalUtils.concat.
> Get rid of String.format usage
> ------------------------------
>
> Key: TAP5-2332
> URL: https://issues.apache.org/jira/browse/TAP5-2332
> Project: Tapestry 5
> Issue Type: Improvement
> Reporter: Michael Mikhulya
> Priority: Minor
> Labels: performance
> Attachments: 0001-TAP5-2332-get-rid-of-String.format-usage.patch
>
>
> During profiling I found that String.format provides much load on CPU.
> In many cases in Tapestry String.format can be easily replaced with simple
> String concatenation.
> Simple JMH (http://openjdk.java.net/projects/code-tools/jmh/) test
> {code:java}
> public class FormatVsConcat {
> private static final String format = "This is a test string with %s";
> private static final String concat1 = "This is a test string with ";
> private static final String concat2 = "test word";
> @GenerateMicroBenchmark
> public String format() {
> return String.format(format, concat2);
> }
> @GenerateMicroBenchmark
> public String concat() {
> return concat1 + concat2;
> }
> }
> {code}
> shows, that concatenation is 366(!) times faster.
> I removed only hot places in tapestry and get following results with apache
> benchmark:
> *Not patched* tapestry version:
> Requests per second: *21.38 /sec* (mean)
> Time per request: *46.764 [ms]* (mean)
> *Patched* tapestry version:
> Requests per second: *27.77 /sec* (mean)
> Time per request: *36.013 [ms]* (mean)
> So we gained 10ms per request or 20% of rendering time.
> If you don't mind I would like to get rid of String.format in all places of
> Tapestry and provide patch. I fixed only hot places which appeared during
> ab-profiling of one concrete page. So it is very likely that not all hot
> places were found and fixed.
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