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  1. JDK
  2. JDK-8222955

Optimize String.replace(CharSequence, CharSequence) for common cases

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Details

    • Enhancement
    • Resolution: Fixed
    • P4
    • 13
    • None
    • core-libs
    • None
    • b20

    Description

      Adding special handling of the case when this String and both arguments are Latin1 encoded shows significant performance improvement.

      With the benchmark
      public class StringReplace {
          public String s = new String("java.lang.String");
          @Benchmark
          public String replace1_0() {
              return s.replace(".", "");
          }
          @Benchmark
          public String replace1_1() {
              return s.replace(".", "/");
          }
          @Benchmark
          public String replace1_2() {
              return s.replace(".", "::");
          }
      }

      the following numbers are observed:
      prior fix:
      Benchmark Mode Cnt Score Error Units
      StringReplace.replace1_0 avgt 18 76.706 ± 2.124 ns/op
      StringReplace.replace1_1 avgt 18 90.630 ± 4.680 ns/op
      StringReplace.replace1_2 avgt 18 110.723 ± 12.093 ns/op

      after fix:
      Benchmark Mode Cnt Score Error Units
      StringReplace.replace1_0 avgt 18 53.609 ± 0.478 ns/op
      StringReplace.replace1_1 avgt 18 24.170 ± 0.214 ns/op
      StringReplace.replace1_2 avgt 18 63.632 ± 0.648 ns/op

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              igerasim Ivan Gerasimov
              igerasim Ivan Gerasimov
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                Created:
                Updated:
                Resolved: