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From "Jochen Kemnade (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (TAP5-2332) Optimize String concatenation performance
Date Thu, 22 May 2014 13:11:03 GMT

    [ https://issues.apache.org/jira/browse/TAP5-2332?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14005892#comment-14005892
] 

Jochen Kemnade commented on TAP5-2332:
--------------------------------------

I tried to express and explain my opinions on the current situation, regarding both the optimizations
and the impact of the proposed solutions, and my proposal to add the concat method to IOCUtilities.
I don't share everyone else's opinions on the topic, but I wouldn't call their opinions "wrong"
anyway.
I didn't say I wanted to commit anything, far from it! Again, I'll create a patch and new
measurements tonight. I can do some basic profiling but I'll do it with visualvm. I'll attach
the results to the issue.

> Optimize String concatenation performance
> -----------------------------------------
>
>                 Key: TAP5-2332
>                 URL: https://issues.apache.org/jira/browse/TAP5-2332
>             Project: Tapestry 5
>          Issue Type: Improvement
>            Reporter: Michael Mikhulya
>            Assignee: Jochen Kemnade
>            Priority: Minor
>              Labels: performance
>         Attachments: 0001-TAP5-2332-get-rid-of-String.format-usage.patch, profile-patched.png,
profile-vanilla.png
>
>
> 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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