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1️⃣🐝🏎️ The One Billion Row Challenge -- A fun exploration of how quickly 1B rows from a text file can be aggregated with Java

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1️⃣🐝🏎️ The One Billion Row Challenge

Status Feb 4: The final leaderboards have been published. Congrats to all the winners, and a big thank you to everyone participating in this challenge as well as to everyone helping to organize it!

Status Feb 3: All entries have been evaluated and I am in the process of finalizing the leaderboards.

Status Feb 1: The challenge has been closed for new submissions. No new pull requests for adding submissions are accepted at this time. Pending PRs will be evaluated over the next few days.

Status Jan 31: The challenge will close today at midnight UTC.

Status Jan 12: As there has been such a large number of entries to this challenge so far (100+), and this is becoming hard to manage, please only create new submissions if you expect them to run in 10 seconds or less on the evaluation machine.

Status Jan 1: This challenge is open for submissions!

Sponsorship

A big thank you to my employer Decodable for funding the evaluation environment and supporting this challenge!

The One Billion Row Challenge (1BRC) is a fun exploration of how far modern Java can be pushed for aggregating one billion rows from a text file. Grab all your (virtual) threads, reach out to SIMD, optimize your GC, or pull any other trick, and create the fastest implementation for solving this task!

1BRC

The text file contains temperature values for a range of weather stations. Each row is one measurement in the format <string: station name>;<double: measurement>, with the measurement value having exactly one fractional digit. The following shows ten rows as an example:

Hamburg;12.0
Bulawayo;8.9
Palembang;38.8
St. John's;15.2
Cracow;12.6
Bridgetown;26.9
Istanbul;6.2
Roseau;34.4
Conakry;31.2
Istanbul;23.0

The task is to write a Java program which reads the file, calculates the min, mean, and max temperature value per weather station, and emits the results on stdout like this (i.e. sorted alphabetically by station name, and the result values per station in the format <min>/<mean>/<max>, rounded to one fractional digit):

{Abha=-23.0/18.0/59.2, Abidjan=-16.2/26.0/67.3, Abéché=-10.0/29.4/69.0, Accra=-10.1/26.4/66.4, Addis Ababa=-23.7/16.0/67.0, Adelaide=-27.8/17.3/58.5, ...}

Submit your implementation by Jan 31 2024 and become part of the leaderboard!

Results

These are the results from running all entries into the challenge on eight cores of a Hetzner AX161 dedicated server (32 core AMD EPYC™ 7502P (Zen2), 128 GB RAM).

# Result (m:s.ms) Implementation JDK Submitter Notes Certificates
1 00:01.535 link 21.0.2-graal Thomas Wuerthinger, Quan Anh Mai, Alfonso² Peterssen GraalVM native binary, uses Unsafe Certificate
2 00:01.587 link 21.0.2-graal Artsiom Korzun GraalVM native binary, uses Unsafe Certificate
3 00:01.608 link 21.0.2-graal Jaromir Hamala GraalVM native binary, uses Unsafe Certificate
00:01.880 link 21.0.1-open Serkan ÖZAL uses Unsafe Certificate
00:01.921 link 21.0.2-graal Van Phu DO GraalVM native binary, uses Unsafe Certificate
00:02.018 link 21.0.2-graal Stephen Von Worley GraalVM native binary, uses Unsafe Certificate
00:02.157 link 21.0.2-graal Roy van Rijn GraalVM native binary, uses Unsafe Certificate
00:02.319 link 21.0.2-graal Yavuz Tas GraalVM native binary, uses Unsafe Certificate
00:02.332 link 21.0.2-graal Marko Topolnik GraalVM native binary, uses Unsafe Certificate
00:02.367 link 21.0.1-open Quan Anh Mai uses Unsafe Certificate
00:02.507 link 21.0.1-open gonix uses Unsafe Certificate
00:02.557 link 21.0.1-open yourwass uses Unsafe Certificate
00:02.820 link 22.ea.32-open Li Lin uses Unsafe Certificate
00:02.995 link 21.0.2-graal tivrfoa GraalVM native binary, uses Unsafe Certificate
00:02.997 link 21.0.1-open gonix Certificate
00:03.095 link 21.0.2-graal Jamal Mulla GraalVM native binary, uses Unsafe Certificate
00:03.210 link 21.0.1-open Quan Anh Mai Certificate
00:03.298 link 21.0.1-graal Subrahmanyam uses Unsafe Certificate
00:03.431 link 21.0.1-graal Roman Musin GraalVM native binary, uses Unsafe Certificate
00:03.469 link 21.0.2-graal Elliot Barlas GraalVM native binary, uses Unsafe Certificate
00:03.698 link 21.0.1-graal Jason Nochlin Certificate
00:03.785 link 21.0.2-graal zerninv GraalVM native binary, uses Unsafe Certificate
00:03.820 link 21.0.2-graal John Ziamos GraalVM native binary, uses Unsafe Certificate
00:03.902 link 21.0.1-open Juan Parera Certificate
00:03.966 link 21.0.1-open Jin Cong Ho uses Unsafe Certificate
00:03.991 link 21.0.1-graal Vaidhy Mayilrangam uses Unsafe Certificate
00:04.066 link 21.0.1-open JesseVanRooy uses Unsafe Certificate
00:04.101 link 21.0.2-graal Jaime Polidura GraalVM native binary, uses Unsafe Certificate
00:04.209 link 21.0.1-open Giovanni Cuccu Certificate
00:04.474 link 21.0.1-open Roman Stoffel Certificate
00:04.676 link 21.0.2-tem Peter Levart Certificate
00:04.684 link 21.0.1-open Florin Blanaru uses Unsafe Certificate
00:04.701 link 21.0.1-open Dr Ian Preston Certificate
00:04.741 link 21.0.1-open Cliff Click uses Unsafe Certificate
00:04.800 link 21.0.1-open Parker Timmins Certificate
00:04.884 link 21.0.1-open Aleksey Shipilëv Certificate
00:04.920 link 21.0.1-graal Subrahmanyam Certificate
00:05.077 link 21.0.2-graal Jonathan Wright GraalVM native binary, uses Unsafe Certificate
00:05.142 link 21.0.1-open Arjen Wisse Certificate
00:05.167 link 21.0.2-open Yevhenii Melnyk Certificate
00:05.235 link 21.0.1-open unbounded Certificate
00:05.336 link java Sumit Chaudhary uses Unsafe Certificate
00:05.354 link 21.0.2-graal Arman Sharif GraalVM native binary, uses Unsafe Certificate
00:05.478 link 21.0.1-open Olivier Bourgain uses Unsafe Certificate
00:05.559 link 21.0.1-graal Panagiotis Drakatos GraalVM native binary Certificate
00:05.887 link 21.0.1-graal Charlie Evans uses Unsafe Certificate
00:05.979 link 21.0.1-graal Sam Pullara Certificate
00:06.166 link 21.0.1-open Jamie Stansfield Certificate
00:06.257 link 21.0.1-graal Stefan Sprenger uses Unsafe Certificate
00:06.392 link 21.0.2-graal Diego Parra Certificate
00:06.576 link 21.0.1-open Andrew Sun uses Unsafe Certificate
00:06.635 link 21.0.1-graal Laake Scates-Gervasi GraalVM native binary, uses Unsafe Certificate
00:06.654 link 21.0.1-graal Jaroslav Bachorik Certificate
00:06.715 link 21.0.1-open Algirdas Raščius Certificate
00:06.884 link 21.0.1-graal rcasteltrione Certificate
00:06.982 link 21.0.1-open Chris Bellew Certificate
00:07.563 link 21.0.1-graal 3j5a Certificate
00:07.680 link 21.0.1-graal Xylitol uses Unsafe Certificate
00:07.712 link 21.0.1-graal Anita SV Certificate
00:07.730 link 21.0.1-open Johannes Schüth Certificate
00:07.894 link 21.0.2-tem Antonio Muñoz Certificate
00:07.925 link 21.0.1-graal Ricardo Pieper Certificate
00:07.948 link java Smoofie uses Unsafe Certificate
00:08.157 link 21.0.1-open JurenIvan Certificate
00:08.167 link 21.0.1-tem Dimitar Dimitrov Certificate
00:08.214 link 21.0.1-open deemkeen Certificate
00:08.255 link 21.0.1-open Mathias Bjerke Certificate
00:08.398 link 21.0.1-open Parth Mudgal uses Unsafe Certificate
00:08.489 link 21.0.1-graal Bang NGUYEN Certificate
00:08.517 link 21.0.1-graal ags uses Unsafe Certificate
00:08.557 link 21.0.1-graal Adrià Cabeza Certificate
00:08.622 link 21.0.1-graal Keshavram Kuduwa uses Unsafe Certificate
00:08.892 link 21.0.1-open Roman Romanchuk Certificate
00:08.896 link 21.0.1-open Andrzej Nestoruk Certificate
00:09.020 link 21.0.1-open yemreinci Certificate
00:09.071 link 21.0.1-open Gabriel Reid Certificate
00:09.352 link 21.0.1-graal Filip Hrisafov Certificate
00:09.725 link 21.0.2-graal Martin GraalVM native binary Certificate
00:09.867 link 21.0.1-graal Ricardo Pieper Certificate
00:09.945 link 21.0.1-open Anthony Goubard Certificate
00:10.092 link 21.0.1-graal Pratham Certificate
00:10.127 link 21.0.1-open Parth Mudgal uses Unsafe Certificate
00:11.577 link 21.0.1-open Eve Certificate
00:10.473 link 21.0.1-open Anton Rybochkin Certificate
00:11.119 link 21.0.1-open lawrey Certificate
00:11.156 link java Yann Moisan Certificate
00:11.167 link 21.0.1-open Nick Palmer Certificate
00:11.352 link 21.0.1-open karthikeyan97 uses Unsafe Certificate
00:11.363 link 21.0.2-tem Guruprasad Sridharan Certificate
00:11.405 link 21.0.1-graal Rafael Merino García Certificate
00:11.406 link 21.0.1-graal gabrielfoo Certificate
00:11.433 link 21.0.1-graal Jatin Gala Certificate
00:11.505 link 21.0.1-open Dmitry Bufistov uses Unsafe Certificate
00:11.744 link 21.0.2-tem Sebastian Lövdahl Certificate
00:11.805 link 21.0.1-graal Cool_Mineman Certificate
00:11.934 link 21.0.1-open arjenvaneerde Certificate
00:12.220 link 21.0.1-open Richard Startin Certificate
00:12.495 link 21.0.1-graal Samuel Yvon GraalVM native binary Certificate
00:12.568 link 21.0.1-graal Vlad Certificate
00:12.800 link java Yonatan Graber Certificate
00:13.013 link 21.0.1-graal Thanh Duong Certificate
00:13.071 link 21.0.1-open Dr Ian Preston Certificate
00:13.729 link java Cedric Boes Certificate
00:13.817 link 21.0.1-open Carlo Certificate
00:14.502 link 21.0.1-graal eriklumme Certificate
00:14.772 link 21.0.1-open Kevin McMurtrie Certificate
00:14.867 link 21.0.1-open Michael Berry Certificate
00:14.900 link java Judekeyser Certificate
00:15.006 link java Paweł Adamski Certificate
00:15.662 link 21.0.1-open Serghei Motpan Certificate
00:16.063 link 21.0.1-open Marek Kohn Certificate
00:16.457 link 21.0.1-open Aleksei Certificate
00:16.953 link 21.0.1-open Gaurav Anantrao Deshmukh Certificate
00:17.046 link 21.0.1-open Dimitris Karampinas Certificate
00:17.086 link java Breejesh Rathod Certificate
00:17.490 link 21.0.1-open Gergely Kiss Certificate
00:17.255 link 21.0.1-open tkosachev Certificate
00:17.520 link 21.0.1-open Farid Certificate
00:17.717 link 21.0.1-open Oleh Marchenko Certificate
00:17.815 link 21.0.1-open Hallvard Trætteberg Certificate
00:17.932 link 21.0.1-open Bartłomiej Pietrzyk Certificate
00:18.251 link 21.0.1-graal Markus Ebner Certificate
00:18.448 link 21.0.1-open Moysés Borges Furtado Certificate
00:18.771 link 21.0.1-graal David Kopec Certificate
00:18.902 link 21.0.1-graal Maxime Certificate
00:19.357 link 21.0.1-graalce Roman Schweitzer Certificate
00:20.691 link 21.0.1-graal Kidlike GraalVM native binary Certificate
00:21.989 link 21.0.1-open couragelee Certificate
00:22.188 link 21.0.1-open Jairo Graterón Certificate
00:22.334 link 21.0.1-open Alberto Venturini Certificate
00:22.457 link 21.0.1-open Ramzi Ben Yahya Certificate
00:22.471 link 21.0.1-open Shivam Agarwal Certificate
00:24.986 link 21.0.1-open kumarsaurav123 Certificate
00:25.064 link 21.0.2-open Sudhir Tumati Certificate
00:26.500 link 21.0.1-open Bruno Félix Certificate
00:28.381 link 21.0.1-open Hampus Certificate
00:29.741 link 21.0.1-open Matteo Vaccari Certificate
00:32.018 link 21.0.1-open Aurelian Tutuianu Certificate
00:34.388 link 21.0.1-tem Tobi Certificate
00:35.875 link 21.0.1-open MahmoudFawzyKhalil Certificate
00:36.180 link 21.0.1-open Horia Chiorean Certificate
00:36.424 link java Manish Garg Certificate
00:38.340 link 21.0.1-open AbstractKamen Certificate
00:41.982 link 21.0.1-open Chris Riccomini Certificate
00:42.893 link 21.0.1-open javamak Certificate
00:46.597 link 21.0.1-open Maeda-san Certificate
00:58.811 link 21.0.1-open Ujjwal Bharti Certificate
01:05.094 link 21.0.1-open Mudit Saxena Certificate
01:05.979 link 21.0.1-graal Hieu Dao Quang Certificate
01:06.790 link 21.0.1-open Karl Heinz Marbaise Certificate
01:06.944 link 21.0.1-open santanu Certificate
01:07.014 link 21.0.1-open pedestrianlove Certificate
01:07.101 link 21.0.1-open Jeevjyot Singh Chhabda Certificate
01:08.811 link 21.0.1-open Aleš Justin Certificate
01:08.908 link 21.0.1-open itaske Certificate
01:09.595 link 21.0.1-tem Antonio Goncalves Certificate
01:09.882 link 21.0.1-open Prabhu R Certificate
01:14.815 link 21.0.1-open twohardthings Certificate
01:25.801 link 21.0.1-open ivanklaric Certificate
01:33.594 link 21.0.1-open Gaurav Mathur Certificate
01:53.208 link java Mahadev K Certificate
01:56.607 link 21.0.1-open Abhilash Certificate
03:43.521 link 21.0.1-open 김예환 Ye-Hwan Kim (Sam) Certificate
03:59.760 link 21.0.1-open Samson Certificate
---
04:49.679 link (Baseline) 21.0.1-open Gunnar Morling

Note that I am not super-scientific in the way I'm running the contenders (see Evaluating Results for the details). This is not a high-fidelity micro-benchmark and there can be variations of up to +-3% between runs. So don't be too hung up on the exact ordering of your entry compared to others in close proximity. The primary purpose of this challenge is to learn something new, have fun along the way, and inspire others to do the same. The leaderboard is only means to an end for achieving this goal. If you observe drastically different results though, please open an issue.

See Entering the Challenge for instructions how to enter the challenge with your own implementation. The Show & Tell features a wide range of 1BRC entries built using other languages, databases, and tools.

Bonus Results

This section lists results from running the fastest N entries with different configurations. As entries have been optimized towards the specific conditions of the original challenge description and set-up (such as size of the key set), challenge entries may perform very differently across different configurations. These bonus results are provided here for informational purposes only. For the 1BRC challenge, only the results in the previous section are of importance.

32 Cores / 64 Threads

For officially evaluating entries into the challenge, each contender is run on eight cores of the evaluation machine (AMD EPYC™ 7502P). Here are the results from running the top 50 entries (as of commit e1fb378a, Feb 2) on all 32 cores / 64 threads (i.e. SMT is enabled) of the machine:

# Result (m:s.ms) Implementation JDK Submitter Notes
1 00:00.323 link 21.0.2-graal Jaromir Hamala GraalVM native binary, uses Unsafe
2 00:00.326 link 21.0.2-graal Thomas Wuerthinger, Quan Anh Mai, Alfonso² Peterssen GraalVM native binary, uses Unsafe
3 00:00.349 link 21.0.2-graal Artsiom Korzun GraalVM native binary, uses Unsafe
00:00.351 link 21.0.2-graal Van Phu DO GraalVM native binary, uses Unsafe
00:00.389 link 21.0.2-graal Stephen Von Worley GraalVM native binary, uses Unsafe
00:00.408 link 21.0.2-graal Yavuz Tas GraalVM native binary, uses Unsafe
00:00.415 link 21.0.2-graal Roy van Rijn GraalVM native binary, uses Unsafe
00:00.499 link 21.0.2-graal Marko Topolnik GraalVM native binary, uses Unsafe
00:00.602 link 21.0.1-graal Roman Musin GraalVM native binary, uses Unsafe
00:00.623 link 21.0.1-open gonix uses Unsafe
00:00.710 link 21.0.2-graal Jamal Mulla GraalVM native binary, uses Unsafe
00:00.727 link 21.0.2-graal tivrfoa GraalVM native binary, uses Unsafe
00:00.774 link 21.0.1-open Serkan ÖZAL uses Unsafe
00:00.788 link 21.0.2-graal Elliot Barlas GraalVM native binary, uses Unsafe
00:00.832 link 21.0.2-graal zerninv GraalVM native binary, uses Unsafe
00:00.840 link 21.0.1-open gonix
00:00.857 link 21.0.2-graal Jaime Polidura GraalVM native binary, uses Unsafe
00:00.880 link 21.0.2-graal John Ziamos GraalVM native binary, uses Unsafe
00:00.939 link 21.0.1-open Aleksey Shipilëv
00:01.026 link 21.0.1-open JesseVanRooy uses Unsafe
00:01.118 link 21.0.2-graal Jonathan Wright GraalVM native binary
00:01.140 link 21.0.2-graal Arman Sharif GraalVM native binary, uses Unsafe
00:01.143 link 21.0.1-open Cliff Click uses Unsafe
00:01.169 link 21.0.2-open Yevhenii Melnyk
00:01.188 link 21.0.1-graal Subrahmanyam uses Unsafe
00:01.193 link 21.0.1-open Florin Blanaru uses Unsafe
00:01.234 link 21.0.1-open Olivier Bourgain uses Unsafe
00:01.242 link 21.0.1-open Quan Anh Mai uses Unsafe
00:01.252 link 21.0.1-open Jin Cong Ho uses Unsafe
00:01.267 link 22.ea.32-open Li Lin uses Unsafe
00:01.363 link 21.0.2-tem Peter Levart
00:01.380 link 21.0.1-graal Jason Nochlin
00:01.391 link 21.0.1-open Quan Anh Mai
00:01.439 link 21.0.1-open Arjen Wisse
00:01.446 link 21.0.1-open Dr Ian Preston
00:01.504 link 21.0.1-open Jamie Stansfield
00:01.514 link 21.0.1-graal Subrahmanyam
00:01.516 link 21.0.1-graal Vaidhy Mayilrangam uses Unsafe
00:01.586 link 21.0.1-open yourwass uses Unsafe
00:01.647 link 21.0.2-graal Diego Parra
00:01.694 link 21.0.1-open Parker Timmins
00:01.694 link 21.0.1-graal Charlie Evans uses Unsafe
00:01.702 link 21.0.1-graal Sam Pullara
00:01.733 link java Sumit Chaudhary uses Unsafe
00:01.742 link 21.0.1-open unbounded
00:02.241 link 21.0.1-graal Stefan Sprenger uses Unsafe
00:02.294 link 21.0.1-open Giovanni Cuccu
00:02.990 link 21.0.1-graal Panagiotis Drakatos GraalVM native binary
00:03.205 link 21.0.1-open Juan Parera
00:10.929 link 21.0.1-open Roman Stoffel

10K Key Set

The 1BRC challenge data set contains 413 distinct weather stations, whereas the rules allow for 10,000 different station names to occur. Here are the results from running the top 40 entries (as of commit e1fb378a, Feb 2) against 1,000,000,000 measurement values across 10K stations (created via ./create_measurements3.sh 1000000000), using eight cores on the evaluation machine:

# Result (m:s.ms) Implementation JDK Submitter Notes
1 00:02.957 link 21.0.2-graal Artsiom Korzun GraalVM native binary, uses Unsafe
2 00:03.058 link 21.0.2-graal Marko Topolnik GraalVM native binary, uses Unsafe
3 00:03.186 link 21.0.2-graal Stephen Von Worley GraalVM native binary, uses Unsafe
00:03.998 link 21.0.2-graal Roy van Rijn GraalVM native binary, uses Unsafe
00:04.042 link 21.0.2-graal Jaromir Hamala GraalVM native binary, uses Unsafe
00:04.289 link 21.0.1-open gonix uses Unsafe
00:04.522 link 21.0.2-graal tivrfoa GraalVM native binary, uses Unsafe
00:04.653 link 21.0.2-graal Jamal Mulla GraalVM native binary, uses Unsafe
00:04.733 link 21.0.1-open gonix
00:04.836 link 21.0.1-graal Subrahmanyam uses Unsafe
00:04.870 link 21.0.2-graal Thomas Wuerthinger, Quan Anh Mai, Alfonso² Peterssen GraalVM native binary, uses Unsafe
00:05.240 link 21.0.2-graal zerninv GraalVM native binary, uses Unsafe
00:05.394 link 21.0.2-graal Yavuz Tas GraalVM native binary, uses Unsafe
00:05.906 link 21.0.2-graal Elliot Barlas GraalVM native binary, uses Unsafe
00:06.086 link 21.0.2-graal Van Phu DO GraalVM native binary, uses Unsafe
00:06.379 link 21.0.2-graal John Ziamos GraalVM native binary, uses Unsafe
00:07.113 link 21.0.2-open Yevhenii Melnyk
00:07.542 link 21.0.2-graal Jonathan Wright GraalVM native binary
00:07.889 link 21.0.1-open Florin Blanaru uses Unsafe
00:07.970 link 21.0.1-open Cliff Click uses Unsafe
00:08.857 link 21.0.1-open Serkan ÖZAL
00:09.333 link 21.0.1-open yourwass uses Unsafe
00:09.722 link 21.0.1-open Aleksey Shipilëv
00:09.777 link 21.0.1-graal Vaidhy Mayilrangam uses Unsafe
00:10.263 link 21.0.1-open Quan Anh Mai uses Unsafe
00:11.154 link 21.0.1-open Parker Timmins
00:13.175 link 21.0.1-open Quan Anh Mai
00:13.245 link 21.0.1-open Dr Ian Preston
00:13.377 link 21.0.1-open Giovanni Cuccu
00:13.761 link 21.0.1-open Juan Parera
00:14.441 link 21.0.2-tem Peter Levart
00:15.548 link 21.0.1-open Jin Cong Ho uses Unsafe
00:17.906 link 21.0.1-graal Jason Nochlin
00:18.770 link 22.ea.32-open Li Lin uses Unsafe
00:19.106 link 21.0.1-open Roman Stoffel
00:20.151 link 21.0.1-graal Roman Musin GraalVM native binary, uses Unsafe; seg-faults occassionally
00:22.953 link 21.0.2-graal Jaime Polidura GraalVM native binary, uses Unsafe
---
DNF link 21.0.1-open JesseVanRooy Incorrect output
DNF link 21.0.1-graal Subrahmanyam Doesn't complete in 60 sec
DNF link 21.0.1-open Arjen Wisse Incorrect output

Prerequisites

Java 21 must be installed on your system.

Running the Challenge

This repository contains two programs:

  • dev.morling.onebrc.CreateMeasurements (invoked via create_measurements.sh): Creates the file measurements.txt in the root directory of this project with a configurable number of random measurement values
  • dev.morling.onebrc.CalculateAverage (invoked via calculate_average_baseline.sh): Calculates the average values for the file measurements.txt

Execute the following steps to run the challenge:

  1. Build the project using Apache Maven:

    ./mvnw clean verify
    
  2. Create the measurements file with 1B rows (just once):

    ./create_measurements.sh 1000000000
    

    This will take a few minutes. Attention: the generated file has a size of approx. 12 GB, so make sure to have enough diskspace.

    If you're running the challenge with a non-Java language, there's a non-authoritative Python script to generate the measurements file at src/main/python/create_measurements.py. The authoritative method for generating the measurements is the Java program dev.morling.onebrc.CreateMeasurements.

  3. Calculate the average measurement values:

    ./calculate_average_baseline.sh
    

    The provided naive example implementation uses the Java streams API for processing the file and completes the task in ~2 min on environment used for result evaluation. It serves as the base line for comparing your own implementation.

  4. Optimize the heck out of it:

    Adjust the CalculateAverage program to speed it up, in any way you see fit (just sticking to a few rules described below). Options include parallelizing the computation, using the (incubating) Vector API, memory-mapping different sections of the file concurrently, using AppCDS, GraalVM, CRaC, etc. for speeding up the application start-up, choosing and tuning the garbage collector, and much more.

Flamegraph/Profiling

A tip is that if you have jbang installed, you can get a flamegraph of your program by running async-profiler via ap-loader:

jbang --javaagent=ap-loader@jvm-profiling-tools/ap-loader=start,event=cpu,file=profile.html -m dev.morling.onebrc.CalculateAverage_yourname target/average-1.0.0-SNAPSHOT.jar

or directly on the .java file:

jbang --javaagent=ap-loader@jvm-profiling-tools/ap-loader=start,event=cpu,file=profile.html src/main/java/dev/morling/onebrc/CalculateAverage_yourname

When you run this, it will generate a flamegraph in profile.html. You can then open this in a browser and see where your program is spending its time.

Rules and limits

  • Any of these Java distributions may be used:
    • Any builds provided by SDKMan
    • Early access builds available on openjdk.net may be used (including EA builds for OpenJDK projects like Valhalla)
    • Builds on builds.shipilev.net If you want to use a build not available via these channels, reach out to discuss whether it can be considered.
  • No external library dependencies may be used
  • Implementations must be provided as a single source file
  • The computation must happen at application runtime, i.e. you cannot process the measurements file at build time (for instance, when using GraalVM) and just bake the result into the binary
  • Input value ranges are as follows:
    • Station name: non null UTF-8 string of min length 1 character and max length 100 bytes, containing neither ; nor \n characters. (i.e. this could be 100 one-byte characters, or 50 two-byte characters, etc.)
    • Temperature value: non null double between -99.9 (inclusive) and 99.9 (inclusive), always with one fractional digit
  • There is a maximum of 10,000 unique station names
  • Line endings in the file are \n characters on all platforms
  • Implementations must not rely on specifics of a given data set, e.g. any valid station name as per the constraints above and any data distribution (number of measurements per station) must be supported
  • The rounding of output values must be done using the semantics of IEEE 754 rounding-direction "roundTowardPositive"

Entering the Challenge

To submit your own implementation to 1BRC, follow these steps:

  • Create a fork of the onebrc GitHub repository.
  • Run ./create_fork.sh <your_GH_user> to copy the baseline implementation to your personal files, or do this manually:
    • Create a copy of CalculateAverage_baseline.java, named CalculateAverage_<your_GH_user>.java, e.g. CalculateAverage_doloreswilson.java.
    • Create a copy of calculate_average_baseline.sh, named calculate_average_<your_GH_user>.sh, e.g. calculate_average_doloreswilson.sh.
    • Adjust that script so that it references your implementation class name. If needed, provide any JVM arguments via the JAVA_OPTS variable in that script. Make sure that script does not write anything to standard output other than calculation results.
    • (Optional) OpenJDK 21 is used by default. If a custom JDK build is required, create a copy of prepare_baseline.sh, named prepare_<your_GH_user>.sh, e.g. prepare_doloreswilson.sh. Include the SDKMAN command sdk use java [version] in the your prepare script.
    • (Optional) If you'd like to use native binaries (GraalVM), add all the required build logic to your prepare_<your_GH_user>.sh script.
  • Make that implementation fast. Really fast.
  • Run the test suite by executing /test.sh <your_GH_user>; if any differences are reported, fix them before submitting your implementation.
  • Create a pull request against the upstream repository, clearly stating
    • The name of your implementation class.
    • The execution time of the program on your system and specs of the same (CPU, number of cores, RAM). This is for informative purposes only, the official runtime will be determined as described below.
  • I will run the program and determine its performance as described in the next section, and enter the result to the scoreboard.

Note: I reserve the right to not evaluate specific submissions if I feel doubtful about the implementation (I.e. I won't run your Bitcoin miner ;).

If you'd like to discuss any potential ideas for implementing 1BRC with the community, you can use the GitHub Discussions of this repository. Please keep it friendly and civil.

The challenge runs until Jan 31 2024. Any submissions (i.e. pull requests) created after Jan 31 2024 23:59 UTC will not be considered.

Evaluating Results

Results are determined by running the program on a Hetzner AX161 dedicated server (32 core AMD EPYC™ 7502P (Zen2), 128 GB RAM).

Programs are run from a RAM disk (i.o. the IO overhead for loading the file from disk is not relevant), using 8 cores of the machine. Each contender must pass the 1BRC test suite (/test.sh). The hyperfine program is used for measuring execution times of the launch scripts of all entries, i.e. end-to-end times are measured. Each contender is run five times in a row. The slowest and the fastest runs are discarded. The mean value of the remaining three runs is the result for that contender and will be added to the results table above. The exact same measurements.txt file is used for evaluating all contenders. See the script evaluate.sh for the exact implementation of the evaluation steps.

Prize

If you enter this challenge, you may learn something new, get to inspire others, and take pride in seeing your name listed in the scoreboard above. Rumor has it that the winner may receive a unique 1️⃣🐝🏎️ t-shirt, too!

FAQ

Q: Can I use Kotlin or other JVM languages other than Java?
A: No, this challenge is focussed on Java only. Feel free to inofficially share implementations significantly outperforming any listed results, though.

Q: Can I use non-JVM languages and/or tools?
A: No, this challenge is focussed on Java only. Feel free to inofficially share interesting implementations and results though. For instance it would be interesting to see how DuckDB fares with this task.

Q: I've got an implementation—but it's not in Java. Can I share it somewhere?
A: Whilst non-Java solutions cannot be formally submitted to the challenge, you are welcome to share them over in the Show and tell GitHub discussion area.

Q: Can I use JNI?
A: Submissions must be completely implemented in Java, i.e. you cannot write JNI glue code in C/C++. You could use AOT compilation of Java code via GraalVM though, either by AOT-compiling the entire application, or by creating a native library (see here.

Q: What is the encoding of the measurements.txt file?
A: The file is encoded with UTF-8.

Q: Can I make assumptions on the names of the weather stations showing up in the data set?
A: No, while only a fixed set of station names is used by the data set generator, any solution should work with arbitrary UTF-8 station names (for the sake of simplicity, names are guaranteed to contain no ; or \n characters).

Q: Can I copy code from other submissions?
A: Yes, you can. The primary focus of the challenge is about learning something new, rather than "winning". When you do so, please give credit to the relevant source submissions. Please don't re-submit other entries with no or only trivial improvements.

Q: Which operating system is used for evaluation?
A: Fedora 39.

Q: My solution runs in 2 sec on my machine. Am I the fastest 1BRC-er in the world?
A: Probably not :) 1BRC results are reported in wallclock time, thus results of different implementations are only comparable when obtained on the same machine. If for instance an implementation is faster on a 32 core workstation than on the 8 core evaluation instance, this doesn't allow for any conclusions. When sharing 1BRC results, you should also always share the result of running the baseline implementation on the same hardware.

Q: Why 1️⃣🐝🏎️ ?
A: It's the abbreviation of the project name: One Billion Row Challenge.

1BRC on the Web

A list of external resources such as blog posts and videos, discussing 1BRC and specific implementations:

License

This code base is available under the Apache License, version 2.

Code of Conduct

Be excellent to each other! More than winning, the purpose of this challenge is to have fun and learn something new.

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1️⃣🐝🏎️ The One Billion Row Challenge -- A fun exploration of how quickly 1B rows from a text file can be aggregated with Java

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