Implementation of Powersort with the aim of integrating it into OpenJDK. Benchmarks are used to ensure that the runtime of the new sorting algorithm is never slower than the current Timsort implementation.

Bring Powersort to Java

Setup

We use Gradle for dependency and build management.

Commandline

Check which Java toolchains Gradle finds:

./gradlew javaToolchains

This should include version >= 23, e.g.:

 + N/A JDK 23-ga
     | Location:           /nix/store/48290hnlb13xmwjw9y16a1s785993bv7-openjdk-23-ga/lib/openjdk
     | Language Version:   23
     | Vendor:             N/A
     | Architecture:       amd64
     | Is JDK:             true
     | Detected by:        Current JVM

Development Setup with nix

The provided shell.nix file can be used to set up a development environment with IntelliJ. The only prerequisite is to have a working nix installation for which there are multiple possibilities, e.g:

# https://github.com/DeterminateSystems/nix-installer?tab=readme-ov-file#determinate-nix-installer
curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix | \
  sh -s -- install

Then the dependencies (JDK23, Gradle, IntelliJ) can be installed with:

nix-shell

IntelliJ

When using nix-shell, some manual configuration is necessary:

STRG ALT SHIFT s -> SDK -> add JDK ->
- home path: /usr/lib/openjdk
- name: usr-lib-jdk
STRG ALT s -> build tools -> gradle ->
- local installation: /usr/lib/gradle
- Gradle JVM: usr-lib-jdk

Tasks

List all Gradle tasks which can be run:

./gradlew tasks

This can also be done graphically in IntelliJ:

Test Cases

Run the task "test":

./gradlew test

Benchmark

There are two different benchmarks. One is based on the JMH benchmark framework, the other one is a custom benchmark implementation.

./gradlew jmh
./gradlew runCustomBenchmark