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Posted to issues@commons.apache.org by "Joe Barnett (Created) (JIRA)" <ji...@apache.org> on 2011/11/15 02:07:51 UTC
[jira] [Created] (LANG-770) StringUtils.join(Object[]) performance
issue if .toString() is not trivial
StringUtils.join(Object[]) performance issue if .toString() is not trivial
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Key: LANG-770
URL: https://issues.apache.org/jira/browse/LANG-770
Project: Commons Lang
Issue Type: Bug
Reporter: Joe Barnett
I have some code that builds syntax trees, and then uses a combination of TreeNode.toString() and StringUtils.join() to recursively convert that syntax tree to a String representation.
example .toString() of a SumNode class, where children is a TreeNode[]:
public String toString() {
return StringUtils.join(children, "+");
}
The problem is, StringUtils.join(Object[], String, int, int) is trying to be too smart about preallocating the StringBuffer size it uses internally, as it does:
bufSize *= ((array[startIndex] == null ? 16 : array[startIndex].toString().length())
+ separator.length());
followed by implicitly calling .toString() on each object in the array:
buf.append(array[i]);
For deep syntax trees, this results in incredibly bad performance, as when traversing the syntax tree, every time we go to the first node, we re-expand the entire tree below that node (which does the same thing with the first node below that, etc).
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[jira] [Commented] (LANG-770) StringUtils.join(Object[])
performance issue if .toString() is not trivial
Posted by "Marcos VinÃcius da Silva (Commented JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/LANG-770?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13227221#comment-13227221 ]
Marcos VinÃcius da Silva commented on LANG-770:
-----------------------------------------------
Seems that the piece of code in the description doesn't exists anymore. The initial buffer size is being calculated as:
{code}
int noOfItems = endIndex - startIndex;
....
StringBuilder buf = new StringBuilder(noOfItems * 16);
{code}
Using this implementation solves the issue?
> StringUtils.join(Object[]) performance issue if .toString() is not trivial
> --------------------------------------------------------------------------
>
> Key: LANG-770
> URL: https://issues.apache.org/jira/browse/LANG-770
> Project: Commons Lang
> Issue Type: Bug
> Reporter: Joe Barnett
>
> I have some code that builds syntax trees, and then uses a combination of TreeNode.toString() and StringUtils.join() to recursively convert that syntax tree to a String representation.
> example .toString() of a SumNode class, where children is a TreeNode[]:
> public String toString() {
> return StringUtils.join(children, "+");
> }
> The problem is, StringUtils.join(Object[], String, int, int) is trying to be too smart about preallocating the StringBuffer size it uses internally, as it does:
> bufSize *= ((array[startIndex] == null ? 16 : array[startIndex].toString().length())
> + separator.length());
> followed by implicitly calling .toString() on each object in the array:
> buf.append(array[i]);
> For deep syntax trees, this results in incredibly bad performance, as when traversing the syntax tree, every time we go to the first node, we re-expand the entire tree below that node (which does the same thing with the first node below that, etc).
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[jira] [Closed] (LANG-770) StringUtils.join(Object[]) performance
issue if .toString() is not trivial
Posted by "Henri Yandell (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/LANG-770?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Henri Yandell closed LANG-770.
------------------------------
Resolution: Not A Problem
Agreed. Resolving this as Not A Problem.
> StringUtils.join(Object[]) performance issue if .toString() is not trivial
> --------------------------------------------------------------------------
>
> Key: LANG-770
> URL: https://issues.apache.org/jira/browse/LANG-770
> Project: Commons Lang
> Issue Type: Bug
> Reporter: Joe Barnett
>
> I have some code that builds syntax trees, and then uses a combination of TreeNode.toString() and StringUtils.join() to recursively convert that syntax tree to a String representation.
> example .toString() of a SumNode class, where children is a TreeNode[]:
> public String toString() {
> return StringUtils.join(children, "+");
> }
> The problem is, StringUtils.join(Object[], String, int, int) is trying to be too smart about preallocating the StringBuffer size it uses internally, as it does:
> bufSize *= ((array[startIndex] == null ? 16 : array[startIndex].toString().length())
> + separator.length());
> followed by implicitly calling .toString() on each object in the array:
> buf.append(array[i]);
> For deep syntax trees, this results in incredibly bad performance, as when traversing the syntax tree, every time we go to the first node, we re-expand the entire tree below that node (which does the same thing with the first node below that, etc).
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