Add an env var to artificially limit the stack size

[konstin]

By default, windows has a stack size limit of 1MB which we run against in debug without any explicit culprit. A new environment variable PUFFIN_STACK_SIZE allows setting an artificially smaller stack size.

[BurntSushi]

Can we create an issue for looking into this? The thing I'm worried about here is that we have 1MB+ stacks lying around, and that probably isn't a great thing. With that said, if this fixes things on Windows I'm fine with it as a temporary work-around I think.

[BurntSushi]

The tokio docs don't make it clear under what conditions this routine fails, but it returns an io::Error on failure. I do wonder under what conditions this can fail, and perhaps it might be better to not panic? On the other hand, if unwrap() is what #[tokio::main] was already doing, then I guess it's probably fine.

[konstin]

#[tokio::main]
async fn main() {
    println!("Hello, world!");
}

expands to

#![feature(prelude_import)]
#[prelude_import]
use std::prelude::rust_2021::*;
#[macro_use]
extern crate std;
fn main() {
    let body = async {
        {
            ::std::io::_print(format_args!("Hello, world!\n"));
        };
    };
    #[allow(clippy::expect_used, clippy::diverging_sub_expression)]
    {
        return tokio::runtime::Builder::new_multi_thread()
            .enable_all()
            .build()
            .expect("Failed building the Runtime")
            .block_on(body);
    }
}

so i think that's what you're expected to do.

[charliermarsh]

@konstin - Do you only see these failures in debug, or release too?

[konstin]

Only in debug mode

[BurntSushi]

Nice I like it.

[BurntSushi]

Actually, given #963, I now realize I'm less a fan of this approach. It'd be really nice to make --all-features continue to work. Otherwise, it breaks things like this. Requiring a non-standard way to enable all features just so we can test with a smaller stack size seems non-ideal to me.

What do you think about configuring this with an environment variable instead?

[BurntSushi]

Do you need to also set the stack size here? i.e., https://docs.rs/tokio/latest/tokio/runtime/struct.Builder.html#method.thread_stack_size

[konstin]

Done

[BurntSushi]

Love it!