XML and JSON parsing test for OpenJDK and GraalVM native compiled app

Building

For Linux

1. Download and install OpenJDK 25 and GraalVM 25
2. Set environment variable GRAALVM_HOME to GraalVM home directory
3. Build project with Maven: mvn clean package
4. Copy dependencies JARs to ./target/ folder: mvn dependency:copy-dependencies -DoutputDirectory=./target/
5. Generate test JSON and XML files with 1 million records each: java -jar ./target/nativetest-0.0.1-SNAPSHOT.jar genjson java -jar ./target/nativetest-0.0.1-SNAPSHOT.jar genxml
6. Build GraalVM native image: mvn -Pnative package

Running test

In case of running on a laptop don't forget to turn power mode to maximum performance mode to prevent CPU performance fluctuations.

Choose one of the mods:

• readxml - for reading and parsing XML in a single thread
• readxmlparallel - for reading XML in a single thread, and parsing with virtual threads
• readjson - for reading and parsing JSON in a single thread
• readjsonparallel - for reading JSON in a single thread, and parsing with virtual threads

Each mode starts with a prompt, and actual parsing starts sfter pressing Enter. This is done to compare Java performance after several consecutive runs within a single process. Time is measured after pressing Enter to the cycle finish.

For 'readjson', for example:

1. For Java: java -jar ./target/nativetest-0.0.1-SNAPSHOT.jar readjson
2. For GraalVM native image: ./target/nativetest readjson

Results on my laptop (AMD Ryzen 7, 8 logical cores) for 10 runs, min - max, in seconds:

Test	OpenJDK	GraalVM native
readxml	52,8 - 54,2	71,4 - 72,8
readxmlparallel	14,0 - 25,3	28,4 - 31,7
readjson	23,5 - 24,7	32,6 - 33,8
readjsonparallel	10,9 - 21,9	20,5 - 26,9

Generating GraalVM reachability-metadata

1. Build the application: mvn clean package
2. Copy dependencies JARs to ./target/ folder: mvn dependency:copy-dependencies -DoutputDirectory=./target/
3. Delete project file ./src/main/resources/META-INF/native-image/org.ng/nativetest/reachability-metadata.json
4. Build metadata with training run: $GRAALVM_HOME/bin/java -agentlib:native-image-agent=config-output-dir=./src/main/resources/META-INF/native-image/org.ng/nativetest/ -jar ./target/nativetest-0.0.1-SNAPSHOT.jar graaltrainingrun