Wrong tokio runtime when using dlopen

[yang282441848]

Scene

I want to use plugins to compose my application by using dlopen.
But something goes wrong when I use async function in my plugins like there is no reactor running, must be called from the context of a Tokio 1.x runtime

Code

There are two parts of my poject.
Project plugin for library and project app for runtime.

Project Plugin

# Cargo.toml
[package]
name = "plugin"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
tokio={version="1.20", features=["full"]}

[lib]
crate-type = ["cdylib", "rlib"]

// lib.rs
use std::any::Any;

pub trait PluginTrait: Send + Sync + Any {
    fn run(&self);
    fn get_aysnc_fn(&self) -> tokio::time::Sleep;
}

struct Plugin;

impl PluginTrait for Plugin {
    fn run(&self) {
        println!("##Hello##");
    }

    fn get_aysnc_fn(&self) -> tokio::time::Sleep {
        tokio::time::sleep(tokio::time::Duration::from_secs(1))
    }
}

#[no_mangle]
pub extern "C" fn create() -> *mut dyn PluginTrait {
    let object = Plugin {};
    let boxed: Box<dyn PluginTrait> = Box::new(object);
    Box::into_raw(boxed)
}

Project app

[package]
name = "app"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
tokio={version="1.20", features=["full"]}
libloading = "0.7"

// main.rs
use std::any::Any;

use libloading::Symbol;

pub trait PluginTrait: Send + Sync + Any {
    fn run(&self);
    fn get_aysnc_fn(&self) -> tokio::time::Sleep;
}

#[tokio::main]
async fn main() {
    let path = "/Users/mason/code/im/rust/demo/plugin/target/debug/libplugin.dylib";

    println!("sleep before dlopen");
    tokio::time::sleep(tokio::time::Duration::from_secs(1)).await;

    unsafe {
        let lib = libloading::Library::new(path).unwrap();
        type CreateSymbol = extern "C" fn() -> *mut dyn PluginTrait;
        let create_fn: Symbol<CreateSymbol> = lib.get(b"create").unwrap();
        let object = create_fn();
        let object = Box::from_raw(object);
        object.run();

        println!("sleep after dlopen");
        object.get_aysnc_fn().await;

        println!("after sleep");
    }
}

Result

##Hello##
sleep before dlopen
sleep after dlopen
thread '<unnamed>' panicked at 'there is no reactor running, must be called from the context of a Tokio 1.x runtime', src/lib.rs:16:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Problem

I don't know the reason why the timer exported by plugin cannot work in the main runtime.
These two timers seem to be the same, there are run in the same thread.And got the same result where I use
tokio::runtime::Builder::new_current_thread().enable_all().build().unwrap()
instead of #[tokio::main]

[taiki-e]

The current runtime is stored in thread-local storage, but I guess it is probably not shared with the plugin and the plugin side has its own thread-local for the current runtime.

[yang282441848]

make sence

but it seems both side run in the same local thread when I debug this app by gdb.

Is there any other way to achieve my goal？

[Darksonn]

Tokio cannot really be used over a dlopen boundary. Your main app would have to expose an API that wraps its own version of Tokio timers, and then the dlopen app would need to use that instead of tokio::time.

[yang282441848]

Why can I use future function in dlopen library like tokio::time,
but cannot use tokio runtime's reference in dlopen library which caused a segement default.

[Darksonn]

Some functions may work over the dlopen boundary, but its a coincidence. You should assume that none of them do.