HackerReposA FIELD GUIDE TO OPEN SOURCE
ProSponsor the shelf♧ 0
← Back to top all-time
mratsim
weave
Nim2019–2025
mratsim / weave

weave

A state-of-the-art multithreading runtime: message-passing based, fast, scalable, ultra-low overhead

Languages & CompilersSystems & InfrastructureAutomation & Workflows
Explore on GitHubRead Hacker News discussions
9Distinct people
30Mentions
0Explicit recommenders
587GitHub stars
REPOSITORY AT A GLANCE

What to know before exploring

What it is

A state-of-the-art multithreading runtime: message-passing based, fast, scalable, ultra-low overhead

GitHub

Where it is used

No documented product use has been verified yet.

What people are saying

No recommendation phrase was found in the indexed comments.

No classified warning is attached to this page. Read the discussions before treating silence as approval.

Also in these discussions

Mentioned in the same Hacker News threads. That is not proof they are substitutes.

This week on Hacker News

Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 3:56:07 PM UTC.

No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.

Mentions over time

HN mentions by year30 dated mentions

Observed mentions: 2019-11-07 21:10:13 UTC to 2025-03-04 17:23:57 UTC.

051015202019-01-01 00:00:00 UTC to 2020-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments20192020-01-01 00:00:00 UTC to 2021-01-01 00:00:00 UTC (exclusive): 18 mentions; 1 submissions, 17 comments2021-01-01 00:00:00 UTC to 2022-01-01 00:00:00 UTC (exclusive): 4 mentions; 0 submissions, 4 comments2022-01-01 00:00:00 UTC to 2023-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments20222023-01-01 00:00:00 UTC to 2024-01-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2024-01-01 00:00:00 UTC to 2025-01-01 00:00:00 UTC (exclusive): 5 mentions; 0 submissions, 5 comments2025-01-01 00:00:00 UTC to 2026-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments2025

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.

View mention counts and date ranges
UTC ranges include their start and exclude their end. Select a period to filter the source evidence.
PeriodStart (UTC)End (exclusive, UTC)MentionsSubmissionsComments
20192019-01-01 00:00:00 UTC2020-01-01 00:00:00 UTC101
20202020-01-01 00:00:00 UTC2021-01-01 00:00:00 UTC18117
20212021-01-01 00:00:00 UTC2022-01-01 00:00:00 UTC404
20222022-01-01 00:00:00 UTC2023-01-01 00:00:00 UTC101
20232023-01-01 00:00:00 UTC2024-01-01 00:00:00 UTC000
20242024-01-01 00:00:00 UTC2025-01-01 00:00:00 UTC505
20252025-01-01 00:00:00 UTC2026-01-01 00:00:00 UTC101

What Hacker News says

30 sources
seanw444·Mar 4, 2025
Definitely agree that there are rough edges, but Nim is in a better state than ever. The LSP isn't great yet, I'll agree with that. There are great optional type libraries for working around exceptions if you don't want them, and the new memory management system (ARC/ORC) is very efficient compared to the old refc implementation (now much more like the C++/Rust approach). For parallel programming, there are also handy libraries. The best of which is Weave[1], but Malebolgia[2] is authored by the creator of Nim and works well in its own way too. There is also active work being done on a new implementation of Nim which intends to clean up the some of the long-term spaghetti that the current implementation has turned into (like most long-term projects do), called Nimony[3], and is also led by the original creator of Nim. It is years away fro
Read the rest
m production according to him, but is at least in the works. I'd have to say Nim is by far my favorite programming language. The terseness, flexibility, and high performance, make it feel almost sci-fi to me. My only major complaint currently is the tooling, but even the tooling is still adequate. I'm glad it exists. Highly recommend. [1] https://github.com/mratsim/weave [2] https://github.com/Araq/malebolgia [3] https://github.com/nim-lang/nimony
In Ask HN: What less-popular systems programming language are you using?
mratsim·Jan 4, 2024
First we can use Laser, which was my initial BLAS experiment in 2019. At the time in particular, OpenBLAS didn't properly use the AVX512 VPUs. (See thread in BLIS https://github.com/flame/blis/issues/352 ), It has made progress since then, still, on my current laptop perf is in the same range Reproduction: - Assuming x86 and preferably Linux. - Install Nim - Install a C compiler with OpenMP support (not the default MacOS Clang) - Install git The repo submodules MKLDNN (now Intel oneDNN) to bench vs Intel JIT Compiler ``` git clone https://github.com/mratsim/laser cd laser git submodule update --init --recursive nim cpp -r --outdir:build -d:danger -d:openmp benchmarks/gemm/gemm_bench_float32.nim ``` This should output something like this ``` Laser production implementation Collected 10 samples in 0.230 seconds Average time: 22.684 ms Stdde
Read the rest
v time: 0.596 ms Min time: 21.769 ms Max time: 23.603 ms Perf: 624.037 GFLOP/s OpenBLAS benchmark Collected 10 samples in 0.216 seconds Average time: 21.340 ms Stddev time: 3.334 ms Min time: 19.346 ms Max time: 27.502 ms Perf: 663.359 GFLOP/s MKL-DNN JIT AVX512 benchmark Collected 10 samples in 0.201 seconds Average time: 19.775 ms Stddev time: 8.262 ms Min time: 15.625 ms Max time: 43.237 ms Perf: 715.855 GFLOP/s ``` Note: the Theoretical peak limit is hardcoded and used my previous machine i9-9980XE. It maybe that your BLAS library is not named libopenblas.so, you can change that here: https://github.com/mratsim/laser/blob/master/benchmarks/thir... Implementation is in this folder: https://github.com/mratsim/laser/tree/master/laser/primitive... in particular, tiling, cache and register optimization: https://github.com/mratsim/laser/blob/master/laser/primitive... AVX512 code generator: https://github.com/mratsim/laser/blob/master/laser/primitive... And generic Scalar/SSE/AVX/AVX2/AVX512 microkernel generator (this is Nim macros to generate code at compile-time): https://github.com/mratsim/laser/blob/master/laser/primitive... I'll come back later with details on how to use my custom HPC threadpool Weave instead of OpenMP (https://github.com/mratsim/weave/tree/master/benchmarks/matm...). As a side bonus it also has parallel nqueens implemented.
In Benchmarking 20 programming languages on N-queens and matrix multiplication
mratsim·Jan 3, 2024
> People use matrix multiplication libraries (often written in Assembly) from every language if they really care about performance. That's because such libraries incorporate 100 PhD theses' worth of tricks that no individual can hope to reinvent in the course of solving another problem. There is absolutely nothing special about Python in this context. You don't have to use Assembly. Case in point, this is as fast as OpenBLAS: https://github.com/mratsim/weave/tree/master/benchmarks/matm...
In Benchmarking 20 programming languages on N-queens and matrix multiplication
cb321·May 15, 2021
First, I like that you said "multicores" and not "multithreads". Default-sharing of all memory is overrated. Sometimes it is useful/necessary, but people reach for threads too readily, IMO. For multiprocessing (like Python's module of that name), you can roll your own little system in probably 100 lines of code or use something like this [1] with an example program [2]. For me, that toy program runs 1.5-2x faster than ripgrep on the same (admittedly limited) problem on Linux. { I suspect this perf diff is due to mmap IO being faster than syscall IO due to SIMD register use as discussed here [3], but this deserves deeper investigation than I have time for right now. If my hunch is right, that may constitute further argumentative support for not leaping to threads even if the programming language "makes them 'easy'", though. } As for th
Read the rest
reads/parallelism with shared memory in Nim..Honestly, there is probably too much to recap. Weave [4] would be a good place to start reading, though, or searching the Nim Forum. [1] https://github.com/c-blake/cligen/blob/master/cligen/procpool.nim [2] https://github.com/c-blake/cligen/blob/master/examples/grl.nim [3] https://news.ycombinator.com/item?id=24842648 [4] https://github.com/mratsim/weave
In Nim 2.0 thoughts
mratsim·Mar 10, 2021
I checked my code dozens of times over days. I thought I had bugs in my code for sure, I couldn't believe glibc and musl had a bug. Then I decided to spend a couple days to learn formal verification, solved all the bugs it found. It worked on my Mac, it worked on Windows, it was still deadlocking on Linux. I replaced my code with raw futexes, no deadlock anymore. And I added logs that showed signaling happened but the thread signaled wasn't unblocked. The futex<->condvar swap is pretty simple. - https://github.com/mratsim/weave/blob/f41a562/weave/cross_th...
In TLA+
mratsim·Mar 8, 2021
I have successfully used TLA+ to clear my 2-phase "put a thread to sleep" protocol from deadlock and livelocks. I also proved that one of the nasty deadlock bugs I was fighting on Linux (but not on Windows or Mac) was actually glibc missing condition variables wakeup signals from time to time. 100% convinced it's worth learning to debug or verify any kind of distributed or multithreaded synchronization primitive. I was bug hunting for a couple weeks before deciding to learn formal verification / model checking via TLA+. Writeup: https://github.com/mratsim/weave/issues/56
In TLA+
edwintorok·Nov 1, 2020
Worth pointing out that the bug is still present in latest glibcs (I can reproduce it on Fedora 33), and affects programs that use pthread_cond_signal, in particular language runtimes like OCaml, Python and .NET that have a global runtime lock. Bugreports: * Fedora: https://bugzilla.redhat.com/show_bug.cgi?id=1889892 * Ubuntu: https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/1899800 Also see https://github.com/mratsim/weave/pull/58/files
In Using TLA+ in the Real World to Understand a Glibc Bug
mratsim·Oct 20, 2020
> no data races for multithreading This is simply not true. Rust borrow checker has no notion of memory models: i.e. sequential consistency, acquire, release or relaxed semantics. The Tokio team needs an additional model checker to ensure no data race in Tokio: - https://github.com/tokio-rs/loom If you want to ensure no data races you need formal verification not a borrow checker, I've compiled my research and a RFC for Nim formal verification here: - https://github.com/mratsim/weave/issues/18 - https://github.com/nim-lang/RFCs/issues/222
In Nim 1.4
mratsim·Oct 15, 2020
I've been diving into parallel reproducible PRNG [1] in the end I choose to have a PRNG based on xoshiro and seeding process that could take loop iteration variables [2] for reproducibility: - [1] https://github.com/mratsim/weave/issues/147 - [2] https://github.com/mratsim/trace-of-radiance/blob/99f7d85/tr... - Usage for parallel raytracing: https://github.com/mratsim/trace-of-radiance/blob/99f7d85/tr... Beyond the JAX paper, the Pedigree-based RNG from Leiserson was interesting as well: - http://supertech.csail.mit.edu/papers/dprng.pdf - https://pdfs.semanticscholar.org/a32c/3b7b8d5d3ebd594bea2d9c... And Haskell's splittable RNG: - http://www.hg.schaathun.net/research/Papers/hgs2015jfp.pdf - http://publications.lib.chalmers.se/records/fulltext/183348/... - http://gee.cs.oswego.edu/dl/papers/oopsla14.pdf
In A Family of Better Random Number Generators

Showing the 15 most recent of 30 sources. Enable JavaScript to search and browse every indexed mention.

MAKE YOURSELF AT HOME

A few shortcuts

/
Search the collection
?
Open this guide
Esc
Close dialogs and navigation

Your saved repositories and interests stay in this browser.