How much faster is Java 15?

A stable machine without any other computational demanding processes running and with Intel® Xeon® Silver 4116 @ 2.1 GHz (12 cores total / 24 threads) and 128 GiB RAM memory, running RHEL 8 x86_64.

Both G1 and Parallel GC for both Java versions to compare the impact of garbage collection. Executed org.optaplanner.examples.app.GeneralOptaPlannerBenchmarkApp with the parameters -Xmx3840M -server -XX:+UseG1GC and -Xmx3840M -server -XX:+UseParallelGC respectively. The results presented in this blog represent the average values taken from 10 iterations of each garbage collector and JDK combination.

Both OpenJDK 11 version "11.0.6" OpenJDK Runtime Environment 18.9 (build 11.0.6+10-LTS) OpenJDK 64-Bit Server VM 18.9 (build 11.0.6+10-LTS, mixed mode)

Both OpenJDK 15 version "15.0.1" OpenJDK Runtime Environment 18.9 (build 15.0.1+9-LTS) OpenJDK 64-Bit Server VM 18.9 (build 15.0.1+9-LTS, mixed mode)

OptaPlanner 7.44.0.Final

Solving a planning problem involves no IO (except a few milliseconds during startup to load the input). A single CPU is completely saturated. It constantly creates many short-lived objects, and the GC collects them afterwards.

Each run solves 11 planning problems with OptaPlanner. Each planning problem runs for 5 minutes and starts with a 30 second JVM warm up which is discarded.

The benchmarks measure the number of scores calculated per second. Higher is better. Calculating a score for a proposed planning solution is non-trivial: it involves many calculations, including checking for conflicts between every entity and every other entity.