Mount hangs when `cli` called with `asyncio.run_in_executor`

I have been experimenting with ratarmount and mostly working nicely so far, thanks

A problem i have hit and struggling to figure out why is that when i call cli(args) directly from my code mounting works as expected

When i shift the same code to run under asyncio.run_in_executor the mountpoint is created but the program hangs as if its running in the foreground

When i control-C my escape hatch unmounts successfully as expected

Im wondering if there is some tty detection or similar going on in the fuse lib, and whether there is a way to force return/backgrounding

Possibly related #76

sys info:

fuse/stable,now 2.9.9-5 amd64 [installed]
#1 SMP Debian 5.10.113-1 (2022-04-29) GNU/Linux
ratarmount==0.11.3 
PYTHON_VERSION = "3.10.2"

[mxmlnkn]

Btw, I’m not sure if it applies to your use case but you could also avoid forking into the background by specifying --foreground and then keep that process or thread in the background yourself. That way it would also be correctly closed on exit.

You could also use ratarmount as a library but that might require more adaption in your code.

[phlax]

possibly related signals http://curiousthing.org/sigttin-sigttou-deep-dive-linux

ive seen a few mentions around mac and linux backgrounding issues <> SIGTTOU

its not clear whether this is the issue or how to resolve, but seems related

working on a minimal repro i realized a few things 8/

firstly it is sys.exiting if successful afaict - when i was thinking my script was successful it was just exiting after mounting the directory

not sure exactly how this is being triggered - i tried both catching SystemExit and adding atexit.register(fun) but neither catch the signal

the only time this doesnt happen is if there is failure, from which im deducing rightly/wrongly that something low-level in FUSE is bypassing the normal python lifecycle

anyhow, exit issues aside - the following code mounts in the background:

import pathlib
import tarfile
import tempfile
import ratarmount


def create_tarball(output):
    with tempfile.TemporaryDirectory() as tmp:
        pathlib.Path(tmp).joinpath("foo.txt").write_text("BAR")
        with tarfile.open(output, "w:gz") as tar:
            tar.add(tmp, arcname=".")
    return output


def mount_dir(tarball):
    ratarmount.cli((tarball, "tmpmount"))


tarball = create_tarball("baz.tar.gz")
mount_dir(tarball)

but the asyncio/executor version sits in the foreground without exiting:

import asyncio
import concurrent


async def mount_dir_async(tarball):
    asyncio.get_event_loop().run_in_executor(
        concurrent.futures.ProcessPoolExecutor(),
        mount_dir,
        tarball)


asyncio.run(mount_dir_async(tarball))