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  1. Tapestry 5
  2. TAP5-2332

Optimize String concatenation performance


    • Type: Improvement
    • Status: Closed
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 5.4
    • Component/s: None
    • Labels:


      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";
          public String format() {
              return String.format(format, concat2);
          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.


        1. 0001-TAP5-2332-get-rid-of-String.format-usage.patch
          10 kB
          Michael Mikhulya
        2. profile-vanilla.png
          191 kB
          Jochen Kemnade
        3. profile-patched.png
          199 kB
          Jochen Kemnade
        4. 0001-TAP5-2332-Add-a-method-for-optimized-String-concaten.patch
          12 kB
          Jochen Kemnade
        5. 0001-TAP5-2332-Replace-String.format-call-by-simple-Strin.patch
          7 kB
          Jochen Kemnade

          Issue Links



              • Assignee:
                jkemnade Jochen Kemnade
                mihasik Michael Mikhulya
              • Votes:
                1 Vote for this issue
                9 Start watching this issue


                • Created: