Java 16 MapMulti Benchmark

• Related StackOverflow question: When and how to perform one to 0..n mapping Stream mapMulti over flatMap as of Java 16
• Early access JavaDoc of Stream::mapMulti(BiConsumer): JavaDoc
• Related OpenJDK issues: JDK-8238286, JDK-8248166

Benchmarks

Stream::flatMap(Function) vs Stream::mapMulti(BiConsumer)

• Input size: 10'000
• The methods generate and flatten a list of size of the same number of elements as the input number itself
• Source: com.nichar.java16.benchmark.MapMulti_FilterMap
• Possible results:

  Benchmark                                   Mode  Cnt   Score   Error  Units
  MapMulti_FlatMap.flatMap                    avgt   25  73.852 ± 3.433  ns/op
  MapMulti_FlatMap.mapMulti                   avgt   25  17.495 ± 0.476  ns/op
  

Stream::filter(Predicate).map(Function) vs Stream::mapMulti(BiConsumer)

• Input size: 10'000
• The methods generate a list with filtered each 3rd value and mapped an increment by 1
• Source: com.nichar.java16.benchmark.MapMulti_FilterMap
• Possible results:

  Benchmark                                   Mode  Cnt    Score  Error  Units
  MapMulti_FilterMap.filterMap                avgt   25   7.973 ± 0.378  ns/op
  MapMulti_FilterMap.mapMulti                 avgt   25   7.765 ± 0.633  ns/op 
  

Stream::flatMap(Function) with Optional::stream() vs Stream::mapMulti(BiConsumer)

• Input size: 10'000
• The methods generate a flattened list from Optional of integers
• Source: com.nichar.java16.benchmark.MapMulti_FlatMap_Optional
• Possible results:

  Benchmark                                   Mode  Cnt   Score   Error  Units
  MapMulti_FlatMap_Optional.flatMap           avgt   25  20.186 ± 1.305  ns/op
  MapMulti_FlatMap_Optional.mapMulti          avgt   25  10.498 ± 0.403  ns/op
  

How to run

Prerequisites

• Needed to be done:
  • Installed Java 16, at least version jdk+16-14
• Included in the repository:
  • JMH dependencies ready in the lib folder: jmh-core-1.23.jar, jmh-generator-annprocess-1.23.jar, jopt-simple-4.6.jar, commons-math3-3.2.jar
  • MANIFEST.MF file pointing the classpath to the libraries

Windows

1. Navigate to the root folder
2. Compile: "C:\Program Files\Java\jdk-16\bin\javac.exe" -cp ./src/main/java ./src/main/java/com/nichar/java16/*.java ./src/main/java/com/nichar/java16/benchmark/*.java -classpath ./lib/* -d ./out/
3. Pack the slim JAR file: "C:\Program Files\Java\jdk-16\bin\jar.exe" cvfm MapMultiBenchmark.jar ./src/main/resources/META-INF/MANIFEST.MF -C ./out/ .
4. Run the JAR file: "C:\Program Files\Java\jdk-16\bin\java.exe" -jar MapMultiBenchmark.jar

Note the path to Java 16 might be different on your machine.

Linux

TO BE DONE