[maven-4.0.x] Expand value interning optimization and add configurable session property (#2495)#10932
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gnodet merged 1 commit intoapache:maven-4.0.xfrom Jul 18, 2025
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…erty (apache#2495) This PR expands the value interning optimization in Maven's XML parsing and fixes transformer usage across all XML factories to improve memory efficiency during Maven builds. Expanded the InterningTransformer in DefaultModelBuilder to intern 27 commonly repeated contexts: **Core Maven coordinates:** - groupId, artifactId, version, namespaceUri, packaging **Dependency-related fields:** - scope, type, classifier **Build and plugin-related fields:** - phase, goal, execution **Repository-related fields:** - layout, policy, checksumPolicy, updatePolicy **Common metadata fields:** - modelVersion, name, url, system, distribution, status **SCM fields:** - connection, developerConnection, tag **Common enum-like values:** - id, inherited, optional Added MAVEN_MODEL_BUILDER_INTERNS session property to allow users to customize which XML contexts are interned during POM parsing: - Supports comma-separated list of field names - User properties take precedence over system properties - Falls back to default contexts when property not set - Handles whitespace and empty values gracefully Usage examples: - mvn clean install -Dmaven.modelBuilder.interns="groupId,artifactId,version" - maven.modelBuilder.interns=groupId,artifactId,version,scope,type Fixed all XML factories to properly use the transformer from XmlReaderRequest: - DefaultSettingsXmlFactory - Now uses transformer - DefaultToolchainsXmlFactory - Now uses transformer - DefaultPluginXmlFactory - Now uses transformer - DefaultModelXmlFactory - Already working, verified Added comprehensive test coverage: - InterningTransformerTest.java - Tests interning logic and session property functionality - XmlFactoryTransformerTest.java - Tests transformer usage across all XML factories 1. **Memory Efficiency**: String interning reduces memory usage by ensuring identical string values share the same object reference 2. **Performance**: Faster string comparisons using == instead of .equals() for interned strings 3. **Comprehensive Coverage**: All XML parsing in Maven (POMs, settings, toolchains, plugins) now benefits from interning 4. **Customizable**: Users can tailor interning to their specific use cases 5. **Maven-specific Optimization**: Targets the most commonly repeated values in Maven files - **Backward Compatible**: No breaking changes - optimization is transparent to users - **Automatic Application**: All XML parsing automatically benefits from interning - **Proper Integration**: Transformers are correctly passed through the XML factory chain - **Conservative Approach**: Only interns commonly repeated values to avoid memory overhead - **Configurable**: Users can customize which fields are interned via session properties (cherry picked from commit e5d985c) # Conflicts: # src/site/markdown/configuration.properties
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