Go-Flavored Concurrency in C

(antonz.org)

65 points | by ibobev a day ago ago

12 comments

  • dandersch a day ago ago

    There is also libmill/libdill, which implements go-style coroutines using setjmp and is usable directly from C (not just as a transpilation target).

    https://libmill.org/

    • adamrezich a day ago ago

      What on earth is going on when you click the Tutorial button on that website?!

      • rurban 19 hours ago ago

        He obviously got hacked by some Indonesian gaming site

  • fsmv a day ago ago

    But select statements are the most important part, and second to that is the fact that goroutines are low cost user space threads

    • kccqzy a day ago ago

      Yes exactly. The author’s design decisions only make sense if this is supposed to be a toy language. On using pthreads rather than fibers:

      > I decided not to use one. I wanted something dead simple — an approach I could explain in a paragraph, using tools every C programmer already knows. The trade-off is that you lose some performance with fine-grained blocking, but in many real-world situations, pthreads work fine if you use a worker pool.

      Sure. You can take a large production Go app and measure how many user space threads are launched; it’s decidedly a lot more than the typical number of threads if you were using pthreads.

      And the author didn’t really justify why select isn’t implemented other than implementation difficulty.

      • throwaway894345 a day ago ago

        I've been using Go regularly since 2012. Worker pools are completely valid and idiomatic in Go. Not sure how you read that quote and concluded "toy".

  • Chu4eeno a day ago ago

    I was expecting proper green threads (it's not like it's impossible in C, there's several C libraries for doing it).

  • BoingBoomTschak a day ago ago

    Just a small "ackchyually": Go is basically a modern Limbo which is itself based on Alef and there was an official "Alef for C" thing in Plan 9 in libthread (https://9p.io/magic/man2html/2/thread)

    EDIT: looks like it was ported on UNIX as part of Plan9Port (https://github.com/9fans/plan9port/blob/master/src/libthread...)

    • MarkSweep a day ago ago

      Russ Cox created libtask, a similar library that runs on multiple UNIXes (UNIXEN?). Based on the COPYRIGHT file, it may be based on libthread.

      https://swtch.com/libtask/

      It’s a great little library. Very easy to read and understand.

    • pjmlp 15 hours ago ago

      And some Oberon-2 in the mix as well, method syntax and unsafe package.

    • bitwize a day ago ago

      As I recall, Bell Labs actually abandoned Alef on Plan 9 because the concurrency primitives they wanted were doable in C so they just went with that.

      • pjmlp 15 hours ago ago

        Nope, they abandoned it because the language design was unsound, and in retrospective a GC was a critical missing piece.

        "Alef appeared in the first and second editions of Plan 9, but was abandoned during development of the third edition.[1][2] Rob Pike later explained Alef's demise by pointing to its lack of automatic memory management, despite Pike's and other people's urging Winterbottom to add garbage collection to the language;[3] also, in a February 2000 slideshow, Pike noted: "…although Alef was a fruitful language, it proved too difficult to maintain a variant language across multiple architectures, so we took what we learned from it and built the thread library for C."

        https://en.wikipedia.org/wiki/Alef_(programming_language)

        "Problem: with C's memory model in a concurrent world, hard to know when to free items.

        All the other languages in this talk are garbage-collected, which is essential to easy concurrent programming"

        http://go-lang.cat-v.org/talks/slides/emerging-languages-cam..., slide 19