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Date: Wed, 21 May 2014 13:42:39 +0000 (UTC)
From: "Jochen Kemnade (JIRA)" <jira@apache.org>
To: commits@tapestry.apache.org
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Subject: [jira] [Commented] (TAP5-2332) Get rid of String.format usage
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    [ https://issues.apache.org/jira/browse/TAP5-2332?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14004667#comment-14004667 ] 

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

I decided to allow non-null CharSequences only because that's usually what you want to concatenate. Again, this implementation is not meant to replace every possible usage of {{String.fomat}} but only the places where it's used for simple concatenation.
And I don't know where "databases" came into play. Even if the application uses one, not all requests are bound to use it. But I think that every request runs through OperationTracker, probably multiple times, and the operation descriptions are often built using String concatenation (see also TAP5-2333).

> 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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