[bug] State does not `drop` fields at application exit

[raphaelmenges]

Describe the bug

Hello 👋

I noticed that fields in the managed state seem to be not dropped at application exit. I created a minimal example based on the template to reproduce the issue:

use tauri::{async_runtime::Mutex, Manager};

// Learn more about Tauri commands at https://tauri.app/develop/calling-rust/
#[tauri::command]
fn greet(name: &str) -> String {
    format!("Hello, {}! You've been greeted from Rust!", name)
}

pub struct MyType {}

impl MyType {
    pub fn new() -> MyType {
        println!("Create MyType."); // Appears in the output.
        MyType {}
    }
}

impl Drop for MyType {
    fn drop(&mut self) {
        println!("Drop MyType."); // Does not appear in the output.
    }
}

pub struct State {
    pub my_type: MyType,
}

impl State {
    pub fn new() -> State {
        State {
            my_type: MyType::new(),
        }
    }
}

#[cfg_attr(mobile, tauri::mobile_entry_point)]
pub fn run() {
    tauri::Builder::default()
        .setup(move |app| {
            app.manage(Mutex::new(State::new()));
            Ok(())
        })
        .plugin(tauri_plugin_opener::init())
        .invoke_handler(tauri::generate_handler![greet])
        .run(tauri::generate_context!())
        .expect("error while running tauri application");
}

Output when ran and exited properly:

raphael@Raphaels-MBP tauri-state-drop-bug % npm run tauri dev

> tauri-state-drop-bug@0.1.0 tauri
> tauri dev

     Running BeforeDevCommand (`npm run dev`)

> tauri-state-drop-bug@0.1.0 dev
> vite


  VITE v6.4.1  ready in 100 ms

  ➜  Local:   http://localhost:1420/
     Running DevCommand (`cargo  run --no-default-features --color always --`)
        Info Watching /Users/raphael/Git/tauri-state-drop-bug/src-tauri for changes...
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.32s
     Running `target/debug/tauri-state-drop-bug`
Create MyType.
raphael@Raphaels-MBP tauri-state-drop-bug %

Reproduction

1. Clone https://github.com/raphaelmenges/tauri-state-drop-bug.
2. Run npm install in the directory.
3. Run npm run tauri dev in the directory.

Expected behavior

The fields in the state should be dropped at application exit.

Full tauri info output

[✔] Environment
    - OS: Mac OS 15.7.1 arm64 (X64)
    ✔ Xcode Command Line Tools: installed
    ✔ Xcode: 16.4
    ✔ rustc: 1.88.0 (6b00bc388 2025-06-23)
    ✔ cargo: 1.88.0 (873a06493 2025-05-10)
    ✔ rustup: 1.28.2 (e4f3ad6f8 2025-04-28)
    ✔ Rust toolchain: stable-aarch64-apple-darwin (default)
    - node: 22.21.0
    - pnpm: 10.12.4
    - npm: 11.6.2

[-] Packages
    - tauri 🦀: 2.9.2
    - tauri-build 🦀: 2.5.1
    - wry 🦀: 0.53.5
    - tao 🦀: 0.34.5
    - @tauri-apps/api  ⱼₛ: 2.9.0
    - @tauri-apps/cli  ⱼₛ: 2.9.3

[-] Plugins
    - tauri-plugin-opener 🦀: 2.5.2
    - @tauri-apps/plugin-opener  ⱼₛ: 2.5.2

[-] App
    - build-type: bundle
    - CSP: unset
    - frontendDist: ../dist
    - devUrl: http://localhost:1420/
    - bundler: Vite

Stack trace

Additional context

No response

[FabianLars]

You're exiting by using the Window close button right? If you were using process.exit() this would make sense but iirc we're trying to drop everything on "native" exits 🤔

Does run_return instead of run (in rust) work better?

[raphaelmenges]

Indeed, I clicked the window close button in the example and the output tells me that the execution is over, yet, no dropping occurred.

Does run_return instead of run (in rust) work better?

You mean using run_return like the following?

#[cfg_attr(mobile, tauri::mobile_entry_point)]
pub fn run() {
    /*
    tauri::Builder::default()
        .setup(move |app| {
            app.manage(Mutex::new(State::new()));
            Ok(())
        })
        .plugin(tauri_plugin_opener::init())
        .invoke_handler(tauri::generate_handler![greet])
        .run(tauri::generate_context!())
        .expect("error while running tauri application");
    */

    let app = tauri::Builder::default()
        .setup(move |app| {
            app.manage(Mutex::new(State::new()));
            Ok(())
        })
        .plugin(tauri_plugin_opener::init())
        .invoke_handler(tauri::generate_handler![greet])
        .build(tauri::generate_context!())
        .expect("error while building tauri application");

    let exit_code = app.run_return(|_app_handle, event| match event {
        tauri::RunEvent::ExitRequested { api, .. } => {
            println!("Exit requested");
            api.prevent_exit();
        }
        _ => {}
    });

    println!("Exit Code =  {}", exit_code);
    std::process::exit(exit_code);
}

Then, the application keeps running after closing the window. Explicitly exiting the application via dock icon, right click, "quit" does not trigger drop as well:

raphael@Raphaels-MBP tauri-state-drop-bug % npm run tauri dev

> tauri-state-drop-bug@0.1.0 tauri
> tauri dev

     Running BeforeDevCommand (`npm run dev`)

> tauri-state-drop-bug@0.1.0 dev
> vite


  VITE v6.4.1  ready in 308 ms

  ➜  Local:   http://localhost:1420/
     Running DevCommand (`cargo  run --no-default-features --color always --`)
        Info Watching /Users/raphael/Git/tauri-state-drop-bug/src-tauri for changes...
    Blocking waiting for file lock on build directory
   Compiling tauri-state-drop-bug v0.1.0 (/Users/raphael/Git/tauri-state-drop-bug/src-tauri)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 33.83s
     Running `target/debug/tauri-state-drop-bug`
Create MyType.
Exit requested
raphael@Raphaels-MBP tauri-state-drop-bug %

The println!("Exit Code = {}", exit_code); statement is also not triggered, which confuses me 😅

[FabianLars]

You mean using run_return like the following?

yes

Explicitly exiting the application via dock icon, right click, "quit" does not trigger drop as well:

hmm yeah i think we don't really handle that quit event well atm eg tauri-apps/tao#1003

---

i'll try to double check the behavior on Windows today

[FabianLars]

what's the behavior if you remove api.prevent_exit(); - didn't see that earlier.

[raphaelmenges]

When I remove api.prevent_exit();, the app quits at hitting the window close button:

raphael@Raphaels-MBP tauri-state-drop-bug % npm run tauri dev

> tauri-state-drop-bug@0.1.0 tauri
> tauri dev

     Running BeforeDevCommand (`npm run dev`)

> tauri-state-drop-bug@0.1.0 dev
> vite


  VITE v6.4.1  ready in 159 ms

  ➜  Local:   http://localhost:1420/
     Running DevCommand (`cargo  run --no-default-features --color always --`)
        Info Watching /Users/raphael/Git/tauri-state-drop-bug/src-tauri for changes...
   Compiling tauri-state-drop-bug v0.1.0 (/Users/raphael/Git/tauri-state-drop-bug/src-tauri)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 3.79s
     Running `target/debug/tauri-state-drop-bug`
Create MyType.
Exit requested
Exit Code =  0
raphael@Raphaels-MBP tauri-state-drop-bug %

hmm yeah i think we don't really handle that quit event well atm

My current workaround is to wrap MyType into an Option and set it to None upon exit requested.

[FabianLars]

My current workaround is to wrap MyType into an Option and set it to None upon exit requested.

yeah that would have been my recommendation as well

i'll try to double check the behavior on Windows today

done, same behavior so it's not macOS' weird exit behavior's fault.

[FabianLars]

Solving this in Tauri is very problematic and i think i see now why we also added a ResourceTable. The only "solution" i can think of will cause all existing state references to become dangling. That sounds worse than not dropping State gracefully 🤔

[Legend-Master]

When I remove api.prevent_exit();, the app quits at hitting the window close button:

What if you remove both the app.prevent_exit and std::process::exit? I think it should run to the end and actually drop the states, that being said though, this will still be a problem with the updater plugin on Windows (it calls std::process::exit before launching the installer so in that case no drop functions can run)

[raphaelmenges]

What if you remove both the app.prevent_exit and std::process::exit?

Still no drop occurs:

raphael@Raphaels-MBP tauri-state-drop-bug % npm run tauri dev

> tauri-state-drop-bug@0.1.0 tauri
> tauri dev

     Running BeforeDevCommand (`npm run dev`)

> tauri-state-drop-bug@0.1.0 dev
> vite


  VITE v6.4.1  ready in 109 ms

  ➜  Local:   http://localhost:1420/
     Running DevCommand (`cargo  run --no-default-features --color always --`)
        Info Watching /Users/raphael/Git/tauri-state-drop-bug/src-tauri for changes...
   Compiling tauri-state-drop-bug v0.1.0 (/Users/raphael/Git/tauri-state-drop-bug/src-tauri)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 3.46s
     Running `target/debug/tauri-state-drop-bug`
Create MyType.
Exit requested
Exit Code =  0
raphael@Raphaels-MBP tauri-state-drop-bug %

[Legend-Master]

Oh well, I think we probably have too much circular reference hanging around that the entire StateManager didn't even drop 😭

[raphaelmenges]

I am fine to drop manually, just good to know that this is expected and something to be improved in the future :)