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https://issues.apache.org/jira/browse/CXF-7716?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16445411#comment-16445411
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ASF GitHub Bot commented on CXF-7716:
-------------------------------------
asoldano commented on a change in pull request #407: [CXF-7716] Reduce
StringBuilders and other performance changes.
URL: https://github.com/apache/cxf/pull/407#discussion_r182964151
##########
File path:
rt/frontend/jaxrs/src/main/java/org/apache/cxf/jaxrs/model/URITemplate.java
##########
@@ -130,10 +130,31 @@ public String getPatternValue() {
private static String escapeCharacters(String expression) {
- StringBuilder sb = new StringBuilder();
- for (int i = 0; i < expression.length(); i++) {
- char ch = expression.charAt(i);
- sb.append(isReservedCharacter(ch) ? "\\" + ch : ch);
+ int length = expression.length();
Review comment:
This being micro-optimization or not should really be supported by benchmark
result data. If this is on a hot path, creating less StringBuilder can really
make some differences.
This said, please note that the fix actually solves 2 issue:
1) it avoids creating the StringBuilder when not needed
2) it prevents useless StringBuilder instances being created whenever a
reserved character is found, as sb.append(isReservedCharacter(ch) ? "\\" + ch :
ch) internally creates another StringBuilder to perform the "\\" + ch
concatenation.
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> IBM Performance Team has found several performance increases
> ------------------------------------------------------------
>
> Key: CXF-7716
> URL: https://issues.apache.org/jira/browse/CXF-7716
> Project: CXF
> Issue Type: Bug
> Components: JAX-RS
> Affects Versions: 3.0.15, 3.2.4
> Reporter: Adam Anderson
> Priority: Major
> Fix For: 3.2.5
>
> Original Estimate: 1h
> Remaining Estimate: 1h
>
> Our performance team has identified several areas of improvement to reduce
> garbage collection and CPU usage.
> First, we reduced the amount of StringBuilders created in HTTPUtils.java and
> ResourceUtils.java.
> Second, we created JAXRSUtils.doMimeTypesIntersect() - a method similar to
> JAXRSUtils.intersectMimeTypes - that doesn't create a HashSet but instead
> returns a boolean when we just need to know if they intersect.
> Third, we found that getting the annotations for parameters to create
> constructor arguments in PerRequestResourceProvider.java is expensive, so we
> cache them in the constructor instead of getting them via reflection every
> request.
> These changes combined result in a ~1.5-2% performance increase.
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