I have a program where, in one particular section it handles a callback from some hardware that needs to complete as fast as possible. Is there a way to stop the Gc from kicking in during the life of this short function?

Perhaps, do a major GC call right before calling this function? Admittedly, not a fool-proof method.

Not sure but maybe play tricks with the build system to mark it as external ? external critical_fn = "%whatever_ocaml_opt_generated" And you’ll have to link .o object file without the `.cmx

Is this “section of code” in Ocaml? If so, it’s tough. But if it’s in C, then I think one can simply acquire the global interpreter lock, and then proceed. If you end up allocating from the ML heap, you might GC (of course) but one presumes that this C code isn’t going to do that, right? Other t…

It’s an OCaml function. I’d really rather not write it in C, if I can help it.

And are you in a multi-threaded context? [ETA: sorry, meant to say “multi-threaded executable”]

Yes, the program is threaded as well.

In that case, there’s not much you can do, yes? The other thread could allocate, causing a GC, and that GC could stop the world. Even your own thread could allocate, causing the same. There’s been an entire thread of work on realtime GC (and also in an SMP setting) specifically to address this is…

You can write your code in Rust though, not in C, with the help of ocaml-rs .

In that case, there’s not much you can do, yes? Yeah, it seemed tough when I asked it. Thanks for the feedback. I’m a little concerned that for my real time needs here, I’ll have to have two programs running; the normal OCaml application, and a separate smaller program written in, say, Rust, t…

Is there a way to turn off garbage collection inside of one function?

Learning

mbacarella April 27, 2020, 5:23am 11

I have noticed this project! It’s nice that there exists a pretty good path now to (along with ctypes) never having to write C ever again.

Topic		Replies	Views
OS threads of external origin Learning	9	467	October 5, 2024
How does OCaml's garbage collector handle external functions Learning	2	768	February 2, 2022
How to prevent a closure that passed to a C function as a callback from being garbage collected prematurely? Learning ffi , ctypes , eio	8	257	July 4, 2024
Calling OCaml from C - random segfaults Learning	6	1330	January 10, 2018
How to run an OCaml program with GC disabled? Learning	4	1579	October 10, 2022

Is there a way to turn off garbage collection inside of one function?

Related topics