reagents

Reagents for multicore OCaml

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3Mentions

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REPOSITORY AT A GLANCE

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What it is

Reagents for multicore OCaml

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Where it is used

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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.

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HN mentions by year3 dated mentions

Observed mentions: 2020-03-31 05:40:47 UTC to 2024-01-08 00:17:37 UTC.

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Period	Start (UTC)	End (exclusive, UTC)	Mentions	Comments
2020	2020-01-01 00:00:00 UTC	2021-01-01 00:00:00 UTC	1	1
2021	2021-01-01 00:00:00 UTC	2022-01-01 00:00:00 UTC	0	0
2022	2022-01-01 00:00:00 UTC	2023-01-01 00:00:00 UTC	1	1
2023	2023-01-01 00:00:00 UTC	2024-01-01 00:00:00 UTC	0	0
2024	2024-01-01 00:00:00 UTC	2025-01-01 00:00:00 UTC	1	1

What Hacker News says

3 sources

JonChesterfield·Jan 8, 2024

The 1978 paper proposes a reasonable set of primitives and then walks through prose examples with them. The book proposes roughly the same primitives (channels are the big change, but stop is barely in the paper) and describes them in a formal notation for state machines. It's the difference between a sketch of a plausible idea and writing down the mathematics. Related though much later, ocaml https://github.com/ocaml-multicore/reagents observed that the send/recv primitives make less sense than a swap primitive. Between occam and the current ocaml effort, concurrent ML is the same sort of model with the details really well thought through (e.g. a thread executing stop gets garbage collected).

In Transputer.net

kcsrk·Dec 17, 2022

Still early days, but I had done some exploratory work in the past on Reagents, a composable lock-free library [1]. Now that OCaml 5 is released, we're reviving this work. It's semantics is weaker than STM -- unlike STM, it doesn't provide serializability but Reagents can compile down to multi-word compare and swap operations, which can be implemented with the help of hardware transactions (when present) or efficient software implementations of it [2]. Hence, Reagent programs should be faster than STM. [1] https://github.com/ocaml-multicore/reagents [2] https://arxiv.org/pdf/2008.02527.pdf

In OCaml 5.0 Multicore is out

kcsrk·Mar 31, 2020

(I work on Multicore OCaml) Multicore OCaml separates the notion of concurrency (overlapped execution) and parallelism (simultaneous execution). You can have one without the other but also have both. The main principle that we're going for is that the compiler should expose just enough support for concurrency and parallelism such that interesting features can live outside the compiler as libraries. This permits the library evolution not to be tied with the language evolution but also permits diversity of libraries beyond what the language developers can aim to achieve. That said, we will build and maintain a few core libraries for concurrency and parallelism. For concurrency, Multicore OCaml exposes effect handlers [1,2,3] which allows you to build generators, async/await, coroutines, etc as library functions (as opposed to primitives nat

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ively supported by the compiler). For example, have a look at aeio [4] which permits the construction of scalable asynchronous I/O in direct-style (no callbacks). aeio is also discussed in [1]. We also plan to extend Lwt to support parallelism. For parallelism, the compiler exposes Domains, which are a wrapper over OS-threads [5]. Domains expose a low-level API that is not suitable for end user consumption. On top of domains, we support channels with bounded buffers [6] (similar to channels in Go, Mvars in GHC Haskell) as well as software transactional memory (STM) that supports shared memory and message passing concurrency and which can take advantage of hardware transactional memory [7]. [1] Concurrent System Programming with Effect Handlers: http://kcsrk.info/papers/system_effects_feb_18.pdf [2] CUFP effects tutorial: https://github.com/ocamllabs/ocaml-effects-tutorial [3] Effects Examples: https://github.com/kayceesrk/effects-examples [4] Aeio: Asynchronous Effect-based IO https://github.com/kayceesrk/ocaml-aeio [5] Domains: https://github.com/ocaml-multicore/ocaml-multicore/blob/para... [6] domainslib: https://github.com/ocaml-multicore/domainslib [7] Reagents: https://github.com/ocaml-multicore/reagents

In Multicore OCaml: March 2020 update