[jira] [Created] (TAP5-2332) Get rid of String.format usage

["Michael Mikhulya (JIRA)" <ji...@apache.org>]

Michael Mikhulya created TAP5-2332:
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             Summary: 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


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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