[
https://issues.apache.org/jira/browse/MNG-7899?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17774626#comment-17774626
]
ASF GitHub Bot commented on MNG-7899:
-------------------------------------
sebastien-doyon commented on PR #1269:
URL: https://github.com/apache/maven/pull/1269#issuecomment-1760038298
Memory allocation profiling using
[ConsoleMavenTransferListener_memalloc_Test.java](https://github.com/sebastien-doyon/maven/blob/MNG-7899_-_4_perf-tests/maven-embedder/src/test/java/org/apache/maven/cli/transfer/ConsoleMavenTransferListener_memalloc_Test.java)
calling the ConsoleMavenTransferListener class 100 million times.
This test shows a drastic decrease of :
- char[] allocation (before : **190 GiB**, after : **85,4 GiB**)
- java.lang.String allocation (before : **45,3 GiB**, after : **3,8 GiB**)
- java.lang.StringBuffer allocation (before : **65,4 GiB**, after : **1,14
GiB**)
- java.text.DecimalFormat allocation (before : **27,4 GiB**, after : **none
recorded**)
- more...
Here the JMC capture for the initial code (file available
[here](https://github.com/sebastien-doyon/maven/raw/MNG-7899_-_4_perf-tests/maven-embedder/recording-initial.jfr))
<img width="1237" alt="Capture d’écran 2023-10-12 à 18 52 20"
src="https://github.com/apache/maven/assets/2573779/9ba678bd-d5bc-41c2-82d8-79f2984d880e";>
Here the JMC capture for the optimised code (file available
[here](https://github.com/sebastien-doyon/maven/raw/MNG-7899_-_4_perf-tests/maven-embedder/recording-optimized.jfr))
<img width="1237" alt="Capture d’écran 2023-10-12 à 18 52 30"
src="https://github.com/apache/maven/assets/2573779/525eff55-386f-4175-805e-12d8d8b02ef7";>
To reproduce:
- checkout the
[MNG-7899-profiling-initial](https://github.com/sebastien-doyon/maven/tree/MNG-7899-profiling-initial)
tag
- execute the following commands :
```
mvn clean verify -Drat.skip=true -DskipTests
mvn test -Drat.skip=true -pl :maven-embedder
-Dtest=**/ConsoleMavenTransferListener_memalloc_Test -Dspotless.check.skip
```
- open the `maven-embedder/recording-initial.jfr` file with JMC
- checkout the
[MNG-7899-profiling-optimised](https://github.com/sebastien-doyon/maven/tree/MNG-7899-profiling-optimised)
tag
- execute the following commands :
```
mvn clean verify -Drat.skip=true -DskipTests
mvn test -Drat.skip=true -pl :maven-embedder
-Dtest=**/ConsoleMavenTransferListener_memalloc_Test -Dspotless.check.skip
```
- open the `maven-embedder/recording-optimized.jfr` file with JMC
> Various memory usage improvements
> ---------------------------------
>
> Key: MNG-7899
> URL: https://issues.apache.org/jira/browse/MNG-7899
> Project: Maven
> Issue Type: Improvement
> Components: Design, Patterns & Best Practices, Embedding,
> General, Logging
> Affects Versions: 4.0.0-alpha-2
> Reporter: sebastien
> Priority: Major
>
> Some optimisations can be applied to the code to reduce the use of temporary
> objects.
> Typical improvements identified are:
> * reduce scope of temporary objects creation to avoid creating when not
> needed. Example :
> {code:java}
> public String toString() {
> StringBuilder sb = new StringBuilder(512);
> if (isEmpty()) {
> return "empty";
> }
> for (MetadataGraphVertex v : vertices) {
> .....{code}
> can be replaced by
> {code:java}
> public String toString() {
> if (isEmpty()) {
> return "empty";
> }
> StringBuilder sb = new StringBuilder(512);
> for (MetadataGraphVertex v : vertices) {
> .....{code}
> * Reuse StringBuilder objects in loops by setting its length to zero
> * Use the StringBuilder.append() with index to avoid String.substring().
> Example:
>
> {code:java}
> int idx = resourceName.lastIndexOf('/');
> buffer.append(idx < 0 ? resourceName : resourceName.substring(idx + 1));
> {code}
> can be replaced by
>
> {code:java}
> int idx = resourceName.lastIndexOf('/');
> if (idx < 0) {
> buffer.append(resourceName);
> } else {
> buffer.append(resourceName, idx + 1, resourceName.length());
> } {code}
>
>
> * Replace dynamic string creation static constants when possible
> * Avoid creating temporary strings with + operator when the final
> destination can be used instead, like PrintStream.print() method
> * Avoir using StringBuilder.append() method and util method MessageUtils.a()
> when the final destination can be used instead, like PrintStream.print()
> method
>
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