Writing a C++20M:N Scheduler from Scratch (EBR, Work-Stealing)
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tiny_coro is a lightweight, educational M:N asynchronous runtime written from scratch using C++20 coroutines. It's designed to strip away the complexity of industrial libraries (like Seastar or Folly) to show the core mechanics clearly.Key Technical Features:M:N Scheduling: Maps M coroutines to N kernel threads (Work-Stealing via Chase-Lev deque).Memory Safety: Implements EBR (Epoch-Based Reclamation) to manage memory safely in lock-free structures without GC.Visualizations: I used Manim (the engine behind 3Blue1Brown) to create animations showing exactly how tasks are stolen and executed.Why I built it: To bridge the gap between "using coroutines" and "understanding the runtime." The code is kept minimal (~1k LOC core) so it can be read in a weekend.
HN · launched Feb 17, 2026 · 18 upvotes (top 33%) · 0 views
Niche: scripting and execution runtimes · 56 launches, 4 in the last 7 days · Explore this niche →
Category and tags
- Horizontal
- Dev tools
- Developer
- Not AI
- Hobby / open-source project
Visit website ↗ Source listing ↗
More like this: all 56 launches in scripting and execution runtimes →
Could you build this?
No Writing an asynchronous M:N runtime with epoch-based reclamation (EBR) and lock-free work-stealing queues in modern C++ requires cutting-edge systems programming and concurrency theory.
What it would actually take: The system requires implementing C++20 coroutine promise types, custom awaiters, and symmetric transfer to switch frames efficiently without OS thread intervention. Concurrency requires lock-free deques (e.g., Chase-Lev) for work-stealing schedulers and safe memory reclamation algorithms like epoch-based reclamation (EBR) to avoid ABA problems and use-after-free bugs. This demands advanced expertise in CPU memory models, atomic memory orderings (acquire/release), cache coherency, and low-level systems debugging.
Discussion
20 comments analyzed.
Competitors mentioned: Seastar, Boost.Coroutines, Felix, Erlang, Go
Concerns raised: C++20 coroutines have high complexity and steep learning curve, Stackless coroutines lack safety/isolation compared to stackful models like Erlang/Go, C++ ecosystem declining, Rust taking over, Per-stack memory overhead with stackful approaches
Feature requests: STM (Software Transactional Memory) support for better safety, Standard library wrappers to simplify C++20 coroutine usage
Competitors
Other products that read as similar to this one : 148 launches clear the similarity bar, closest 8 shown.
Attention rank: #62 of 149 (itself plus its competitors, highest first, normalized so YC and Product Hunt are compared fairly).
Launched 109 days after the earliest competitor.
- cpp-coroutine-server-framework · github · 2026-10-20 · 24 upvotes · similarity 0.45
- genpark-async-event-loop-reactor-scheduler-skill · github · 2026-09-28 · 7 upvotes · similarity 0.44
- C discrete event SIM w stackful coroutines runs 45x faster than SimPy · hn · 2026-02-03 · 69 upvotes · similarity 0.43
- genpark-work-stealing-thread-pool-deque-skill · github · 2026-09-28 · 7 upvotes · similarity 0.42
- Forkrun · hn · 2026-03-27 · 151 upvotes · similarity 0.42
- CCo · hn · 2026-08-03 · 5 upvotes · similarity 0.42
- I wrote a minimal memory allocator in C · hn · 2025-11-23 · 137 upvotes · similarity 0.42
- Lockstep · hn · 2026-03-16 · 8 upvotes · similarity 0.42
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