rustuv deadlocks at shutdown when spawning a "daemon" subprocess

[glandium]

To work around #14410, I'm using forget() to make a subprocess stay up longer than its (rust) parent. But while that works with libnative, that deadlocks on shutdown with rustuv. It's not even wait()ing on its child, because once the child quits, it's still stuck.

extern crate green;
extern crate rustuv;

use std::io::process;
use std::io::process::Command;

#[start]
fn start(argc: int, argv: **u8) -> int {
    green::start(argc, argv, rustuv::event_loop, main)
}

fn main() {
    let process = Command::new("sleep")
        .arg("10")
        .stdin(process::Ignored)
        .stdout(process::Ignored)
        .stderr(process::Ignored)
        .detached()
        .spawn()
        .ok();
    unsafe { std::mem::forget(process); }
}

If you wait the 10 seconds it takes for sleep to end, the above test program still is stuck.

[huonw]

I personally don't think we need to be guaranteeing that (a) rustuv works correctly without running destructors, or (b) that the behaviour of green and native match in every scenario (especially one like this).

cc @alexcrichton

[alexcrichton]

Closing, forget is an unsafe function which is not intended to be used for something like this. This is basically waiting for #13854 to be resolved.