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Top 23 Concurrency Open-Source Projects
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For that specific use case you could also try `yazi`[0], which is a TUI file browser that has image (and other filetypes) preview built in.
[0] https://github.com/sxyazi/yazi
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Project mention: Show HN: Sycamore – next gen Rust UI library powered by fine-grained reactivity | news.ycombinator.com | 2026-04-01
I looked briefly, but is anyone aware of the differences between Yew[1] and Sycamore[2]? Presumably they are both Elm-influenced Rust web UI libraries named after trees, but it's unclear to me why I should use one versus the other.
1. https://github.com/yewstack/yew
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Project mention: How to Build a Real-Time Chat App with WebSockets (And Why It Works) | dev.to | 2026-03-19
PHP can handle WebSockets. Projects like Ratchet and Swoole exist for exactly this reason. The traditional PHP execution model — spin up a process per request, run the script, die — doesn't naturally fit persistent connections. But the ecosystem has evolved.
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Project mention: Using LMAX Disruptor to build a high-performance in-memory event broker in Java. | dev.to | 2025-12-28
As a Python developer, I'd typically reach for libraries like PyPubSub or Blinker for event handling, which work well for I/O-bound applications but struggle with CPU-intensive event processing due to the GIL for Python versions before 3.14. Go's channel-based concurrency model handles events elegantly with goroutines, and libraries like EventBus provide pub-sub patterns that feel natural in Go's ecosystem. However, neither ecosystem has a direct equivalent to Disruptor's mechanical sympathy approach. Python's interpreter overhead and Go's garbage collector (though better than Python's) both introduce latency that becomes visible at millions of events per second. If you're building a system where a few microseconds per event multiplied by millions of events actually matters (financial systems, real-time analytics, game servers), Java's mature JIT compilation, fine-tuned GC options, and libraries like Disruptor that exploit CPU cache behavior offer performance that's hard to match.
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Project mention: Standing on shoulders: the stack that makes Floci start in ~24ms | dev.to | 2026-05-21
Vert.x is the layer where Floci uses things directly. It's Netty with ergonomics: an event loop, a router, protocol-specific APIs for HTTP, DNS, TCP, WebSockets, gRPC, all sharing the same threading model.
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Everything he lists is solved by effect-ts [1] bar, obviously, the language support.
[1] https://effect.website/
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Akka
A platform to build and run apps that are elastic, agile, and resilient. SDK, libraries, and hosted environments.
Project mention: Byte Buddy is a code generation and manipulation library for Java | news.ycombinator.com | 2025-08-08> The better question is why use Java for anything these days.
Java (the language) is pretty much "C for the JVM." By that, I mean frameworks/libraries intended for maximum potential use in languages running on the JVM (such as Kotlin, Scala, and of course Java) all support Java (the language) interoperability. Many written in alternate languages targeting the JVM, such as Akka[0], typically have some degree of Java (the language) support as well.
While I prefer to program in one of the alternate programming languages targeting the JVM, I understand why many OSS projects are implemented in Java (the language) for the reasons outlined above.
0 - https://github.com/akka/akka
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That's it. Everything else — async/await, actors, work-stealing executors, lock-free data structures — lives in the ecosystem (tokio, rayon, crossbeam, actix, etc.).
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The BLoC (Business Logic Component) pattern is where serious teams land. Google's own Flutter team uses it internally. Nubank, one of the world's largest digital banks with 90 million customers, built its app on it. BMW runs it in production. The flutter_bloc package has logged over 1.4 million downloads on pub.dev. That's not hype. That's validation at scale.
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> Actually much closer than anything I saw in other mainstream languages eg Java or Go.
https://github.com/sourcegraph/conc
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That's it. Everything else — async/await, actors, work-stealing executors, lock-free data structures — lives in the ecosystem (tokio, rayon, crossbeam, actix, etc.).
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That's it. Everything else — async/await, actors, work-stealing executors, lock-free data structures — lives in the ecosystem (tokio, rayon, crossbeam, actix, etc.).
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Hatchet | Full-Stack Engineer | NYC or SF or REMOTE (US and EU) | https://hatchet.run
Hey HN! I'm Alexander, one of the founders of Hatchet. Hatchet is an open-source platform for running background jobs at scale.
We're hiring engineers who are excited to build the next class of engineering primitives, starting with queues, background tasks and durable execution. We started in early 2024 after launching our distributed task queue (https://news.ycombinator.com/item?id=39643136).
Hatchet is currently used by thousands of engineers for all kinds of workloads: log ingestion pipelines, code review agents, video encoding, GPU scheduling, etc. Our target customer is fast-growing startups who have a strong need for background jobs system. These days, that tends to be AI companies, though we're general-purpose and not exclusively targeted for AI workloads.
Stack: Postgres, Go, Typescript, React, Kubernetes
Applying: email me at alexander@hatchet.run and tell me about something impressive you've built, along with your CV and why you're interested in Hatchet.
Note that we're fully open-source, which you can check out here: https://github.com/hatchet-dev/hatchet (and if you have thoughts / opinions / questions about the codebase, please include those in your note!)
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Concurrent Ruby
Modern concurrency tools including agents, futures, promises, thread pools, supervisors, and more. Inspired by Erlang, Clojure, Scala, Go, Java, JavaScript, and classic concurrency patterns.
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Project mention: Go beyond Goroutines: introducing the Reactive paradigm | news.ycombinator.com | 2025-10-27
NOTE:
The open source projects on this list are ordered by number of github stars.
The number of mentions indicates repo mentiontions in the last 12 Months or
since we started tracking (Dec 2020).
Concurrency discussion
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I built a Rust replacement for ccusage — 1,742x faster, near-zero overhead
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A note from our sponsor - SaaSHub
www.saashub.com | 7 Jun 2026
Index
What are some of the best open-source Concurrency projects? This list will help you:
| # | Project | Stars |
|---|---|---|
| 1 | yazi | 39,035 |
| 2 | yew | 32,668 |
| 3 | ava | 20,853 |
| 4 | Swoole | 18,878 |
| 5 | Disruptor | 18,273 |
| 6 | Vert.x | 14,671 |
| 7 | effect | 14,520 |
| 8 | Akka | 13,276 |
| 9 | rayon | 13,042 |
| 10 | bloc | 12,449 |
| 11 | moodycamel | 12,298 |
| 12 | Taskflow | 11,999 |
| 13 | ZeroMQ | 10,892 |
| 14 | Orleans | 10,787 |
| 15 | conc | 10,374 |
| 16 | actix | 9,211 |
| 17 | system_design | 9,202 |
| 18 | crossbeam | 8,464 |
| 19 | Android-RxJava | 7,512 |
| 20 | hatchet | 7,291 |
| 21 | Concurrent Ruby | 5,829 |
| 22 | promise-fun | 5,133 |
| 23 | RxGo | 5,088 |
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