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https://issues.apache.org/jira/browse/GROOVY-6360?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17283559#comment-17283559
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Volkan Yazici commented on GROOVY-6360:
---------------------------------------
Thanks for your prompt reply and investigation [~paulk]. Regarding your
conclusion, I don't agree that this issue applies to Java. See the following
{{CharSequence}} implementation:
{code:java}
private static final class Bike implements CharSequence {
private int toStringInvocationCount = 0;
@Override
public int length() {
return 4;
}
@Override
public char charAt(int index) {
return "BIKE".charAt(index);
}
@Override
public CharSequence subSequence(int start, int end) {
return "BIKE".subSequence(start, end);
}
@Override
public String toString() {
toStringInvocationCount++;
return "BIKE";
}
}
{code}
In this case {{toString()}} will not even be called. I am aware that in your
{{MyCharSeq}}, all {{length()}}, {{charAt(int)}}, {{subSequence(int,int)}}
methods falls back to {{toString()}}, which is the culprit for the excessive
{{toString()}} invocations. Though this appears like an inefficient
implementation to me, rather than a fault of Java.
For the records, I was expecting GROOVY-9637 to fix my issue, but it did not.
> GString performance is slow with String's method
> ------------------------------------------------
>
> Key: GROOVY-6360
> URL: https://issues.apache.org/jira/browse/GROOVY-6360
> Project: Groovy
> Issue Type: Improvement
> Components: groovy-jdk
> Affects Versions: 2.1.7
> Reporter: Linh Pham
> Priority: Minor
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> GString implementation of String's method is very expensive. With trim(), it
> can be 10 times slower than String's counterpart.
> *Steps to reproduce:*
> A small test program showed GString.trim() is 10 times slower than
> String.trim().
> {code}
> def a = " content "
> def b = " ${'content'} "
> println "a class: ${a.class}" //output: class java.lang.String
> println "b class: ${b.class}" //output: class
> org.codehaus.groovy.runtime.GStringImpl
> long start = System.currentTimeMillis()
> 10000000.times {
> a.trim()
> }
> println "String trim completed in ${System.currentTimeMillis() - start} ms."
> //output *909* ms
> start = System.currentTimeMillis()
> 10000000.times {
> b.trim()
> }
> println "GString trim completed in ${System.currentTimeMillis() - start} ms."
> //output: *9321 *ms
> {code}
> We can get around the problem by calling toString() on GString before
> invoking methods, BUT it should be supported inside the Groovy runtime.
> More info at this thread: http://markmail.org/thread/4cti6dgb7pmrzqbl
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