Hacker News Reader

Comment by medo-bear | Hacker News Reader

maybe i am missing something but this is old news for embeddable common lisp. see threading section in this article from 1994[0], or is this extreme-threading different somehow? there is also a recent llvm-based implementation [1] that aims for direct lisp-cpp interface.

i know my usage of the word "just" might suggest otherwise but i am not trying to deminish this feat. i use common lisp for scientific work and whenever i hear about something cool in another language i ask myself can i do this with my toolset. this is the reason i am asking this.

[0] https://dl.acm.org/doi/pdf/10.1145/224139.1379849

[1] https://clasp-developers.github.io/

View on HN

I think it’s just that this is possible in (the recently released) Julia 1.9 and wasn’t possible in earlier versions due to how thread-local storage and the GC worked, and doing this can be useful sometimes.

Your link 0 is cool, but is fairly different from the new stuff here. Some key differences are that the paper uses a conservative garbage collector (so enjoy random memory leaks) as a way to get around the problems of interop with C. Also, while that paper supports multithreading, as far as I can tell, it meant n-thread to 1 core (i.e. concurrent) multithreading (which is what the term usually referred to before multicore cpus were common), while Julia supports n threads to m cores (see Java's long awaited project Loom) which has a bunch of additional challenges. The last thing to mention is that the paper required a near complete rewrite of the lisp compiler. While that's an option for a simple language like Lisp, it's not as feasible for more complicated languages.

Multithreading is handled by C so N-M should be no problem because the key thing is N. If threads are managed from ECL instead then, if available, it will use pthreads [0]

ECL is not a rewrite of some THE compiler, it is a whole implementation. This actually goes toward your point that Julia cant do this because the language is not seperate from its compiler, but it is not because julia is more complicated than common lisp

Common Lisp has been called many things, rarely simple. Its spec is over 1000 pages

[0] https://ecl.common-lisp.dev/static/manual/Native-threads.htm...

I think the title was intended to be more playful and fun than a serious take on the most technically intense applications of threading in C++.

Reply on news.ycombinator.com