[LANG-1358] Improve StringUtils#replace throughput

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 3.6
• Fix Version/s: 3.7
• External issue URL: https://github.com/apache/commons-lang/pull/300
• Assignee: Pascal Schumacher
• Reporter: Pascal Schumacher
• Created: 12/Oct/17 17:30
• Updated: 10/Nov/17 16:41
• Resolved: 12/Oct/17 17:36

Description

StringUtils#replace uses substring to append a String region into a StringBuilder. This causes useless copies, as StringBuilder#append can take start and end indexes.

Modification:

Use proper StringBuilder#append overload (https://docs.oracle.com/javase/8/docs/api/java/lang/StringBuilder.html#append-java.lang.CharSequence-int-int-).

Result:

Based on benchmark from JOOQ’s post (https://blog.jooq.org/2017/10/11/benchmarking-jdk-string-replace-vs-apache-commons-stringutils-replace):

Benchmark Mode Cnt Score Error Units
StringReplaceBenchmark.testFastStringReplaceLongStringOneMatch thrpt 21
7546534,219 ± 145523,962 ops/s
StringReplaceBenchmark.testStringUtilsReplaceLongStringOneMatch thrpt
21 7353512,552 ± 124498,228 ops/s

StringReplaceBenchmark.testFastStringReplaceLongStringSeveralMatches
thrpt 21 5077255,810 ± 62358,937 ops/s
StringReplaceBenchmark.testStringUtilsReplaceLongStringSeveralMatches
thrpt 21 4108357,612 ± 92909,038 ops/s

StringReplaceBenchmark.testFastStringReplaceShortStringOneMatch thrpt
21 15911221,949 ± 541064,693 ops/s
StringReplaceBenchmark.testStringUtilsReplaceShortStringOneMatch thrpt
21 10677897,475 ± 491091,973 ops/s

StringReplaceBenchmark.testFastStringReplaceShortStringSeveralMatches
thrpt 21 9271742,251 ± 220150,121 ops/s
StringReplaceBenchmark.testStringUtilsReplaceShortStringSeveralMatches
thrpt 21 6158829,188 ± 99637,607 ops/s

source: https://github.com/apache/commons-lang/pull/300