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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 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!

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
1 00:02.575 link 21.0.1-open Quan Anh Mai Quan Anh Mai's implementation, using Unsafe
2 00:02.708 link 21.0.1-graal Thomas Wuerthinger, Quan Anh Mai, Alfonso² Peterssen GraalVM native binary
3 00:02.855 link 21.0.1-graal Roy van Rijn GraalVM native binary
00:03.258 link 21.0.1-open Quan Anh Mai
00:03.321 link 21.0.1-graal Artsiom Korzun
00:03.539 link 21.0.1-graal Marko Topolnik
00:03.714 link 21.0.1-graal Jason Nochlin
00:04.362 link java Van Phu DO
00:04.823 link 21.0.1-graal Jamal Mulla
00:04.959 link 21.0.1-graal Yavuz Tas
00:04.996 link 21.0.1-graal Elliot Barlas
00:05.218 link 21.0.1-open John Ziamos
00:05.478 link 21.0.1-open Olivier Bourgain
00:05.960 link 21.0.1-graal Vaidhy Mayilrangam
00:05.979 link 21.0.1-graal Sam Pullara
00:06.140 link 21.0.1-open zerninv
00:06.166 link 21.0.1-open Jamie Stansfield
00:06.576 link 21.0.1-open Andrew Sun
00:06.715 link 21.0.1-open Algirdas Raščius
00:07.730 link 21.0.1-open Johannes Schüth
00:07.809 link 21.0.1-graal Roman Musin
00:07.925 link 21.0.1-graal Ricardo Pieper
00:07.913 link 21.0.1-open parkertimmins
00:08.167 link 21.0.1-tem Dimitar Dimitrov
00:08.214 link 21.0.1-open deemkeen
00:08.398 link 21.0.1-open Parth Mudgal
00:08.489 link 21.0.1-graal Bang NGUYEN
00:08.517 link 21.0.1-graal ags
00:08.689 link 21.0.1-open Roman Stoffel
00:08.892 link 21.0.1-open Roman Romanchuk
00:09.020 link 21.0.1-open yemreinci
00:09.071 link 21.0.1-open Gabriel Reid
00:09.117 link 21.0.1-graal Keshavram Kuduwa
00:09.352 link 21.0.1-graal Filip Hrisafov
00:09.867 link 21.0.1-graal Ricardo Pieper
00:10.127 link 21.0.1-open Parth Mudgal
00:10.553 link 21.0.1-graal Xylitol
00:10.473 link 21.0.1-open Anton Rybochkin
00:11.119 link 21.0.1-open lawrey
00:11.167 link 21.0.1-open Nick Palmer
00:11.405 link 21.0.1-graal Rafael Merino García
00:11.433 link 21.0.1-graal Jatin Gala
00:11.805 link 21.0.1-graal Cool_Mineman
00:11.934 link 21.0.1-open arjenvaneerde
00:11.987 link 21.0.1-graal Stefan Sprenger
00:12.220 link 21.0.1-open Richard Startin
00:12.495 link 21.0.1-graal Samuel Yvon GraalVM native binary
00:12.565 link 21.0.1-open Anthony Goubard
00:12.568 link 21.0.1-graal Vlad
00:13.013 link 21.0.1-graal Thanh Duong
00:13.148 link 21.0.1-open Charlie Evans
00:13.623 link 21.0.1-open Pratham
00:13.817 link 21.0.1-open Carlo
00:14.772 link 21.0.1-open Kevin McMurtrie
00:14.867 link 21.0.1-open Michael Berry
00:15.662 link 21.0.1-open Serghei Motpan
00:15.752 link 21.0.1-tem Jaroslav Bachorik
00:16.379 link 21.0.1-open Dr Ian Preston
00:17.490 link 21.0.1-open Gergely Kiss
00:17.717 link 21.0.1-open Oleh Marchenko
00:17.815 link 21.0.1-open Hallvard Trætteberg
00:18.251 link 21.0.1-graal Markus Ebner
00:18.313 link 21.0.1-open Jairo Graterón
00:18.448 link 21.0.1-open Moysés Borges Furtado
00:18.771 link 21.0.1-graal David Kopec
00:18.902 link 21.0.1-graal Maxime
00:19.357 link 21.0.1-graalce Roman Schweitzer
00:20.691 link 21.0.1-graal Kidlike GraalVM native binary
00:21.989 link 21.0.1-open couragelee
00:22.457 link 21.0.1-open Ramzi Ben Yahya
00:28.381 link 21.0.1-open Hampus
00:32.018 link 21.0.1-open Aurelian Tutuianu
00:34.388 link 21.0.1-tem Tobi
00:36.180 link 21.0.1-open Horia Chiorean
00:36.212 link 21.0.1-open kumarsaurav123
00:38.340 link 21.0.1-open AbstractKamen
00:41.982 link 21.0.1-open Chris Riccomini
00:42.893 link 21.0.1-open javamak
00:45.447 link 21.0.1-open Arman Sharif
00:46.597 link 21.0.1-open Maeda-san
00:58.811 link 21.0.1-open Ujjwal Bharti
01:05.094 link 21.0.1-open Mudit Saxena
01:06.790 link 21.0.1-open Karl Heinz Marbaise
01:06.944 link 21.0.1-open santanu
01:07.014 link 21.0.1-open pedestrianlove
01:08.811 link 21.0.1-open Aleš Justin
01:08.908 link 21.0.1-open itaske
01:09.882 link 21.0.1-open Prabhu R
01:14.815 link 21.0.1-open twohardthings
01:25.801 link 21.0.1-open ivanklaric
01:33.594 link 21.0.1-open Gaurav Mathur
01:45.082 link 21.0.1-open Eve
01:56.607 link 21.0.1-open Abhilash
03:43.521 link 21.0.1-open 김예환 Ye-Hwan Kim (Sam)
03:59.760 link 21.0.1-open Samson
---
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 ~ +-5% 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.

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.

  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

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.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.

Sponsorship

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

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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