Matcher performance improvements

[Rémi Forax]

Le 13/08/2009 03:30, Martin Buchholz a écrit :
> Hi regex/String team,
>
> We would like to contribute a performance improvement for Matcher.
>    

Just a minor comment, there is not @since 1.7

Rémi

> Please file a bug.
>
> category: java_util_regex
> Synopsis: Faster Matcher by replacing StringBuffer with StringBuilder
>
> Description:
> The old Matcher API and implementation depend on the old StringBuffer class.
> The use of StringBuilder gives measurable performance improvement in
> real world applications.
> http://cr.openjdk.java.net/~martin/webrevs/openjdk7/Matcher-perf/
> Written by Jeremy Manson.
>
> Here's a microbenchmark, where it gives 25% win:
>
> public class StringReplace {
>    static String jabber = "Twas brillig, and the slithy toves " +
>        "Did gyre and gimble in the wabe; " +
>        "All mimsy were the borogoves, " +
>        "And the mome raths outgrabe. " +
>        " " +
>        "Beware the Jabberwock, my son! " +
>        "The jaws that bite, the claws that catch! " +
>        "Beware the Jubjub bird, and shun " +
>        "The frumious Bandersnatch!" +
>        " " +
>        "He took his vorpal sword in hand: " +
>        "Long time the manxome foe he sought— " +
>        "So rested he by the Tumtum tree, " +
>        "And stood awhile in thought. " +
>        " " +
>        "And as in uffish thought he stood, " +
>        "The Jabberwock, with eyes of flame, " +
>        "Came whiffling through the tulgey wood, " +
>        "And burbled as it came! " +
>        " " +
>        "One, two! One, two! and through and through " +
>        "The vorpal blade went snicker-snack! " +
>        "He left it dead, and with its head " +
>        "He went galumphing back. " +
>        " " +
>        "And hast thou slain the Jabberwock? " +
>        "Come to my arms, my beamish boy! " +
>        "O frabjous day! Callooh! Callay!" +" " +
>        "He chortled in his joy. " +
>        " " +
>        "'Twas brillig, and the slithy toves " +
>        "Did gyre and gimble in the wabe; " +
>        "All mimsy were the borogoves, " +
>        "And the mome raths outgrabe?";
>
>    public static void replace() {
>      long start = System.currentTimeMillis();
>      for (int i = 0; i<  100000; i++) {
>        jabber.replaceAll("the", "ze");
>      }
>      long stop = System.currentTimeMillis();
>      System.out.println(stop);
>      System.out.println(start);
>
>      System.out.println(stop - start);
>    }
>
>    public static void main(String[] args) {
>      for (int i = 0; i<  5; i++) {
>        replace();
>      }
>    }
> }
>