[TAP5-2332] Optimize String concatenation performance

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 5.4
• Labels: patch performance
• Assignee: Jochen Kemnade
• Reporter: Michael Mikhulya
• Created: 19/May/14 13:40
• Updated: 05/Mar/15 13:48
• Resolved: 13/Nov/14 08:18

Description

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

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;
    }
}

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.

Issue Links

• is related to: TAP5-1874 OperationTracker description logging improvement