Comments on: String Concatenation Options http://www.antwerkz.com/string-concatenation-options/ Wed, 03 Mar 2010 14:22:54 +0000 http://wordpress.org/?v=abc hourly 1 By: Kirk http://www.antwerkz.com/string-concatenation-options/comment-page-1/#comment-15665 Kirk Tue, 24 Feb 2009 14:43:33 +0000 http://www.antwerkz.com/?p=1505#comment-15665 I calculated the variances myself. GC runs quite often but on my kit always for less than .2ms. I've just finished running an object creation profiler. The top 5 objects in this test are char[] from 3 different sources, String from a single source, and StringBuilder. 1) char[] from I don't know where. 2) char[] from java.util.Arrays.copyOfRange(Arrays.java:3209) java.lang.String.(String.java:216) java.lang.StringBuilder.toString(StringBuilder.java:430) Test.concat(Test.java:8) Test.main(Test.java:46) 3) char[] from java.lang.AbstractStringBuilder.(AbstractStringBuilder.java:45) java.lang.StringBuilder.(StringBuilder.java:68) Test.concat(Test.java:8) Test.main(Test.java:46) 4) String from java.lang.String.(String.java:203) java.lang.StringBuilder.toString(StringBuilder.java:430) Test.concat(Test.java:8) Test.main(Test.java:46) 5) StringBuilder from java.lang.AbstractStringBuilder.(AbstractStringBuilder.java:44) java.lang.StringBuilder.(StringBuilder.java:68) Test.concat(Test.java:8) Test.main(Test.java:46) All the top 5 sources of objects appear to come from the concat. If so, this microbenchmark may not properly account for the cost of a proper object lifecycle. IE, GC of objects quickly thrown away is close to 0. If you don't throw objects away like is done in this bench, gc cost should skyrocket for concat. I calculated the variances myself. GC runs quite often but on my kit always for less than .2ms. I’ve just finished running an object creation profiler. The top 5 objects in this test are char[] from 3 different sources, String from a single source, and StringBuilder.

1) char[] from I don’t know where.

2) char[] from
java.util.Arrays.copyOfRange(Arrays.java:3209)
java.lang.String.(String.java:216)
java.lang.StringBuilder.toString(StringBuilder.java:430)
Test.concat(Test.java:8)
Test.main(Test.java:46)

3) char[] from
java.lang.AbstractStringBuilder.(AbstractStringBuilder.java:45)
java.lang.StringBuilder.(StringBuilder.java:68)
Test.concat(Test.java:8)
Test.main(Test.java:46)

4) String from

java.lang.String.(String.java:203)
java.lang.StringBuilder.toString(StringBuilder.java:430)
Test.concat(Test.java:8)
Test.main(Test.java:46)

5) StringBuilder from

java.lang.AbstractStringBuilder.(AbstractStringBuilder.java:44)
java.lang.StringBuilder.(StringBuilder.java:68)
Test.concat(Test.java:8)
Test.main(Test.java:46)

All the top 5 sources of objects appear to come from the concat. If so, this microbenchmark may not properly account for the cost of a proper object lifecycle. IE, GC of objects quickly thrown away is close to 0. If you don’t throw objects away like is done in this bench, gc cost should skyrocket for concat.

]]> By: Kirk http://www.antwerkz.com/string-concatenation-options/comment-page-1/#comment-15664 Kirk Tue, 24 Feb 2009 07:13:10 +0000 http://www.antwerkz.com/?p=1505#comment-15664 Can we see the variance between runs? Can we see the variance between runs?

]]> By: About String Concatenation in Java or “don’t fear the +” « Schneide Blog http://www.antwerkz.com/string-concatenation-options/comment-page-1/#comment-15661 About String Concatenation in Java or “don’t fear the +” « Schneide Blog Mon, 23 Feb 2009 06:10:21 +0000 http://www.antwerkz.com/?p=1505#comment-15661 [...] Lee has a nice writeup of the most prominent concatenation options. But imho he misses out some things and his benchmark [...] [...] Lee has a nice writeup of the most prominent concatenation options. But imho he misses out some things and his benchmark [...]

]]> By: jlee http://www.antwerkz.com/string-concatenation-options/comment-page-1/#comment-15656 jlee Thu, 29 Jan 2009 22:49:29 +0000 http://www.antwerkz.com/?p=1505#comment-15656 I updated my test and tried that and it did run consistently faster but only for an aggregate ~6ms over a million runs. So not much of an improvement but might help in some cases. Maybe. I updated my test and tried that and it did run consistently faster but only for an aggregate ~6ms over a million runs. So not much of an improvement but might help in some cases. Maybe.

]]> By: Christian Ullenboom http://www.antwerkz.com/string-concatenation-options/comment-page-1/#comment-15655 Christian Ullenboom Thu, 29 Jan 2009 21:55:37 +0000 http://www.antwerkz.com/?p=1505#comment-15655 You can add one more option: String s = new StringBuilder(128).append("Loop ")..... This is useful for longer Strings. You can add one more option:

String s = new StringBuilder(128).append(“Loop “)…..

This is useful for longer Strings.

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