Wasm stack trace from JsFutures

ineiti · October 15, 2021, 9:40am

I'm still trying to work with JsFutures in Wasm, but I discovered the following behaviour. When running the code

use wasm_bindgen_futures::JsFuture;
use web_sys::window;
use js_sys::Promise;
use wasm_bindgen_test::*;

#[wasm_bindgen_test]
async fn test_wait_ms() {
    console_error_panic_hook::set_once();

    wasm_logger::init(wasm_logger::Config::new(log::Level::Trace));

    log::debug!("Running test");
    wait_ms(100).await;
    wait_ms(100).await;
    panic!("Show stack/heap");
}

async fn wait_ms(ms: i32) {
    let promise = Promise::new(&mut |yes, _| {
        let win = window().unwrap();
        win.set_timeout_with_callback_and_timeout_and_arguments_0(&yes, ms)
            .unwrap();
    });
    let js_fut = JsFuture::from(promise);
    js_fut.await;
}

I see a long stack-trace after the panic (there must be a proper way to print the stack / heap) which grows longer if I add more wait_ms in the test-method.

Does that mean that Wasm is not correctly cleaning up the JsFuture.await? Or does it only mean that I don't know how to read the stack/heap trace produced by panic?

Here is the output from the above code:

console.<computed>	@	(index):15
(anonymous)	@	wasm-bindgen-test:593
logError	@	wasm-bindgen-test:218
imports.wbg.__wbg_error_4bb6c2a97407129a	@	wasm-bindgen-test:591
$console_error_panic_hook::error::h5ee162e8c00de58d	@	wasm-bindgen-test_bg.wasm:0x2b4f0d
$console_error_panic_hook::hook_impl::hf848f1eeb18f8b7d	@	wasm-bindgen-test_bg.wasm:0x21a73a
$console_error_panic_hook::hook::h750d81068679507e	@	wasm-bindgen-test_bg.wasm:0x359d0b
$core::ops::function::Fn::call::h1609cb0630d0bbf1	@	wasm-bindgen-test_bg.wasm:0x34266b
$std::panicking::rust_panic_with_hook::he9bfe03219d715ba	@	wasm-bindgen-test_bg.wasm:0x282706
$std::panicking::begin_panic::{{closure}}::he40fef5e17f6b58e	@	wasm-bindgen-test_bg.wasm:0x2cb221
$std::sys_common::backtrace::__rust_end_short_backtrace::hd8ae9a7213f7132a	@	wasm-bindgen-test_bg.wasm:0x2f3753
$std::panicking::begin_panic::hcfcf2bc744e752a2	@	wasm-bindgen-test_bg.wasm:0x32e89f
$wasm_webrtc::test_wait_ms::test_wait_ms::{{closure}}::h1db7019032ef2421	@	wasm-bindgen-test_bg.wasm:0x181bea
$<core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::hd6f9d6d2994b98f2	@	wasm-bindgen-test_bg.wasm:0x2aa15b
$wasm_bindgen_test::__rt::Context::execute_async::{{closure}}::h656701822149525f	@	wasm-bindgen-test_bg.wasm:0x204a56
$<core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h6d304df6f7bf69ff	@	wasm-bindgen-test_bg.wasm:0x2a9e5f
$<wasm_bindgen_test::__rt::TestFuture<F> as core::future::future::Future>::poll::{{closure}}::{{closure}}::h8eb6ed72ffbe352a	@	wasm-bindgen-test_bg.wasm:0x2d7253
$wasm_bindgen::convert::closures::invoke0_mut::h2c699ce350272107	@	wasm-bindgen-test_bg.wasm:0x2bbdf1
__wbg_adapter_54	@	wasm-bindgen-test:364
cb0	@	wasm-bindgen-test:536
window.__wbg_test_invoke	@	(index):25
(anonymous)	@	wasm-bindgen-test:541
handleError	@	wasm-bindgen-test:369
imports.wbg.__wbg_wbgtestinvoke_6d22b7d64550c12f	@	wasm-bindgen-test:529
$wasm_bindgen_test::__rt::__wbg_test_invoke::h5911ea9eca5183b7	@	wasm-bindgen-test_bg.wasm:0x250c48
$<wasm_bindgen_test::__rt::TestFuture<F> as core::future::future::Future>::poll::{{closure}}::hd4695e4a25d6c3a8	@	wasm-bindgen-test_bg.wasm:0x2bd317
$scoped_tls::ScopedKey<T>::set::h711076e3a91c0bdf	@	wasm-bindgen-test_bg.wasm:0x26e371
$<wasm_bindgen_test::__rt::TestFuture<F> as core::future::future::Future>::poll::h5bba7ba7a2e0e0c9	@	wasm-bindgen-test_bg.wasm:0x17f779
$<wasm_bindgen_test::__rt::ExecuteTests as core::future::future::Future>::poll::h2174ed68299da2c2	@	wasm-bindgen-test_bg.wasm:0xed29b
$wasm_bindgen_test::__rt::Context::run::{{closure}}::hc7d4368f014d2456	@	wasm-bindgen-test_bg.wasm:0x1f6e7c
$<core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h8b334f1807679992	@	wasm-bindgen-test_bg.wasm:0x27aee7
$wasm_bindgen_futures::future_to_promise::{{closure}}::{{closure}}::hf3c00e2c51b5e763	@	wasm-bindgen-test_bg.wasm:0x195533
$<core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h2c38d676517e2203	@	wasm-bindgen-test_bg.wasm:0x2aa8a8
$wasm_bindgen_futures::task::singlethread::Task::run::h8c5979b40af7554e	@	wasm-bindgen-test_bg.wasm:0x1e2236
$wasm_bindgen_futures::queue::QueueState::run_all::h2311101bcc23bb9c	@	wasm-bindgen-test_bg.wasm:0x2041aa
$wasm_bindgen_futures::queue::Queue::new::{{closure}}::h5ae3ab5cab960077	@	wasm-bindgen-test_bg.wasm:0x3089a8
$<dyn core::ops::function::FnMut<(A,)>+Output = R as wasm_bindgen::closure::WasmClosure>::describe::invoke::hed2c3548a8b32456	@	wasm-bindgen-test_bg.wasm:0x293997
__wbg_adapter_41	@	wasm-bindgen-test:268
real	@	wasm-bindgen-test:201
Promise.then (async)		
(anonymous)	@	wasm-bindgen-test:871
logError	@	wasm-bindgen-test:218
imports.wbg.__wbg_then_c2361a9d5c9a4fcb	@	wasm-bindgen-test:870
$js_sys::Promise::then::hea5fad77105c5bb9	@	wasm-bindgen-test_bg.wasm:0x301ca4
$wasm_bindgen_futures::queue::Queue::push_task::h3f6874a6247774a6	@	wasm-bindgen-test_bg.wasm:0x2383bf
$wasm_bindgen_futures::task::singlethread::Task::wake_by_ref::{{closure}}::hb50f853c0f646b13	@	wasm-bindgen-test_bg.wasm:0x336b87
$std::thread::local::LocalKey<T>::try_with::h8b1d60d0756bcecb	@	wasm-bindgen-test_bg.wasm:0x291e7b
$std::thread::local::LocalKey<T>::with::h05495a9c85e65f64	@	wasm-bindgen-test_bg.wasm:0x2fcbc2
$wasm_bindgen_futures::task::singlethread::Task::wake_by_ref::h4261b943cb25dea5	@	wasm-bindgen-test_bg.wasm:0x2a98c1
$wasm_bindgen_futures::task::singlethread::Task::into_raw_waker::raw_wake::h5af0691eca61cb4a	@	wasm-bindgen-test_bg.wasm:0x301c37
$core::task::wake::Waker::wake::h6300b2e573224863	@	wasm-bindgen-test_bg.wasm:0x31e083
$<wasm_bindgen_futures::JsFuture as core::convert::From<js_sys::Promise>>::from::finish::hba302f5e6889d0c7	@	wasm-bindgen-test_bg.wasm:0x1964e1
$<wasm_bindgen_futures::JsFuture as core::convert::From<js_sys::Promise>>::from::{{closure}}::h50a92c72efa5bed8	@	wasm-bindgen-test_bg.wasm:0x2e269d
$core::ops::function::FnOnce::call_once::hfbf3c39e2cb7b4e6	@	wasm-bindgen-test_bg.wasm:0x2fe198
$<T as wasm_bindgen::closure::WasmClosureFnOnce<A,R>>::into_fn_mut::{{closure}}::h3e7b4776c0c0ecec	@	wasm-bindgen-test_bg.wasm:0x2f77d0
$<dyn core::ops::function::FnMut<(A,)>+Output = R as wasm_bindgen::closure::WasmClosure>::describe::invoke::hed2c3548a8b32456	@	wasm-bindgen-test_bg.wasm:0x293997
__wbg_adapter_41	@	wasm-bindgen-test:268
real	@	wasm-bindgen-test:201
Promise.then (async)		
(anonymous)	@	wasm-bindgen-test:875
logError	@	wasm-bindgen-test:218
imports.wbg.__wbg_then_6c9a4bf55755f9b8	@	wasm-bindgen-test:874
$js_sys::Promise::then2::h60b2eed0742f1f57	@	wasm-bindgen-test_bg.wasm:0x2e2885
$<wasm_bindgen_futures::JsFuture as core::convert::From<js_sys::Promise>>::from::h0dd8cb6e262cd257	@	wasm-bindgen-test_bg.wasm:0x15e24e
$wasm_webrtc::test_wait_ms::wait_ms::{{closure}}::h38a83862219ffad9	@	wasm-bindgen-test_bg.wasm:0x1e2a97
$<core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h438655e6fea14639	@	wasm-bindgen-test_bg.wasm:0x2a9c22
$wasm_webrtc::test_wait_ms::test_wait_ms::{{closure}}::h1db7019032ef2421	@	wasm-bindgen-test_bg.wasm:0x181b4f
$<core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::hd6f9d6d2994b98f2	@	wasm-bindgen-test_bg.wasm:0x2aa15b
$wasm_bindgen_test::__rt::Context::execute_async::{{closure}}::h656701822149525f	@	wasm-bindgen-test_bg.wasm:0x204a56
$<core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h6d304df6f7bf69ff	@	wasm-bindgen-test_bg.wasm:0x2a9e5f
$<wasm_bindgen_test::__rt::TestFuture<F> as core::future::future::Future>::poll::{{closure}}::{{closure}}::h8eb6ed72ffbe352a	@	wasm-bindgen-test_bg.wasm:0x2d7253
$wasm_bindgen::convert::closures::invoke0_mut::h2c699ce350272107	@	wasm-bindgen-test_bg.wasm:0x2bbdf1
__wbg_adapter_54	@	wasm-bindgen-test:364
cb0	@	wasm-bindgen-test:536
window.__wbg_test_invoke	@	(index):25
(anonymous)	@	wasm-bindgen-test:541
handleError	@	wasm-bindgen-test:369
imports.wbg.__wbg_wbgtestinvoke_6d22b7d64550c12f	@	wasm-bindgen-test:529
$wasm_bindgen_test::__rt::__wbg_test_invoke::h5911ea9eca5183b7	@	wasm-bindgen-test_bg.wasm:0x250c48
$<wasm_bindgen_test::__rt::TestFuture<F> as core::future::future::Future>::poll::{{closure}}::hd4695e4a25d6c3a8	@	wasm-bindgen-test_bg.wasm:0x2bd317
$scoped_tls::ScopedKey<T>::set::h711076e3a91c0bdf	@	wasm-bindgen-test_bg.wasm:0x26e371
$<wasm_bindgen_test::__rt::TestFuture<F> as core::future::future::Future>::poll::h5bba7ba7a2e0e0c9	@	wasm-bindgen-test_bg.wasm:0x17f779
$<wasm_bindgen_test::__rt::ExecuteTests as core::future::future::Future>::poll::h2174ed68299da2c2	@	wasm-bindgen-test_bg.wasm:0xed29b
$wasm_bindgen_test::__rt::Context::run::{{closure}}::hc7d4368f014d2456	@	wasm-bindgen-test_bg.wasm:0x1f6e7c
$<core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h8b334f1807679992	@	wasm-bindgen-test_bg.wasm:0x27aee7
$wasm_bindgen_futures::future_to_promise::{{closure}}::{{closure}}::hf3c00e2c51b5e763	@	wasm-bindgen-test_bg.wasm:0x195533
$<core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h2c38d676517e2203	@	wasm-bindgen-test_bg.wasm:0x2aa8a8
$wasm_bindgen_futures::task::singlethread::Task::run::h8c5979b40af7554e	@	wasm-bindgen-test_bg.wasm:0x1e2236
$wasm_bindgen_futures::queue::QueueState::run_all::h2311101bcc23bb9c	@	wasm-bindgen-test_bg.wasm:0x2041aa
$wasm_bindgen_futures::queue::Queue::new::{{closure}}::h5ae3ab5cab960077	@	wasm-bindgen-test_bg.wasm:0x3089a8
$<dyn core::ops::function::FnMut<(A,)>+Output = R as wasm_bindgen::closure::WasmClosure>::describe::invoke::hed2c3548a8b32456	@	wasm-bindgen-test_bg.wasm:0x293997
__wbg_adapter_41	@	wasm-bindgen-test:268
real	@	wasm-bindgen-test:201
Promise.then (async)		
(anonymous)	@	wasm-bindgen-test:871
logError	@	wasm-bindgen-test:218
imports.wbg.__wbg_then_c2361a9d5c9a4fcb	@	wasm-bindgen-test:870
$js_sys::Promise::then::hea5fad77105c5bb9	@	wasm-bindgen-test_bg.wasm:0x301ca4
$wasm_bindgen_futures::queue::Queue::push_task::h3f6874a6247774a6	@	wasm-bindgen-test_bg.wasm:0x2383bf
$wasm_bindgen_futures::task::singlethread::Task::wake_by_ref::{{closure}}::hb50f853c0f646b13	@	wasm-bindgen-test_bg.wasm:0x336b87
$std::thread::local::LocalKey<T>::try_with::h8b1d60d0756bcecb	@	wasm-bindgen-test_bg.wasm:0x291e7b
$std::thread::local::LocalKey<T>::with::h05495a9c85e65f64	@	wasm-bindgen-test_bg.wasm:0x2fcbc2
$wasm_bindgen_futures::task::singlethread::Task::wake_by_ref::h4261b943cb25dea5	@	wasm-bindgen-test_bg.wasm:0x2a98c1
$wasm_bindgen_futures::task::singlethread::Task::into_raw_waker::raw_wake::h5af0691eca61cb4a	@	wasm-bindgen-test_bg.wasm:0x301c37
$core::task::wake::Waker::wake::h6300b2e573224863	@	wasm-bindgen-test_bg.wasm:0x31e083
$<wasm_bindgen_futures::JsFuture as core::convert::From<js_sys::Promise>>::from::finish::hba302f5e6889d0c7	@	wasm-bindgen-test_bg.wasm:0x1964e1
$<wasm_bindgen_futures::JsFuture as core::convert::From<js_sys::Promise>>::from::{{closure}}::h50a92c72efa5bed8	@	wasm-bindgen-test_bg.wasm:0x2e269d
$core::ops::function::FnOnce::call_once::hfbf3c39e2cb7b4e6	@	wasm-bindgen-test_bg.wasm:0x2fe198
$<T as wasm_bindgen::closure::WasmClosureFnOnce<A,R>>::into_fn_mut::{{closure}}::h3e7b4776c0c0ecec	@	wasm-bindgen-test_bg.wasm:0x2f77d0
$<dyn core::ops::function::FnMut<(A,)>+Output = R as wasm_bindgen::closure::WasmClosure>::describe::invoke::hed2c3548a8b32456	@	wasm-bindgen-test_bg.wasm:0x293997
__wbg_adapter_41	@	wasm-bindgen-test:268
real	@	wasm-bindgen-test:201
Promise.then (async)		
(anonymous)	@	wasm-bindgen-test:875
logError	@	wasm-bindgen-test:218
imports.wbg.__wbg_then_6c9a4bf55755f9b8	@	wasm-bindgen-test:874
$js_sys::Promise::then2::h60b2eed0742f1f57	@	wasm-bindgen-test_bg.wasm:0x2e2885
$<wasm_bindgen_futures::JsFuture as core::convert::From<js_sys::Promise>>::from::h0dd8cb6e262cd257	@	wasm-bindgen-test_bg.wasm:0x15e24e
$wasm_webrtc::test_wait_ms::wait_ms::{{closure}}::h38a83862219ffad9	@	wasm-bindgen-test_bg.wasm:0x1e2a97
$<core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h438655e6fea14639	@	wasm-bindgen-test_bg.wasm:0x2a9c22
$wasm_webrtc::test_wait_ms::test_wait_ms::{{closure}}::h1db7019032ef2421	@	wasm-bindgen-test_bg.wasm:0x181a39
$<core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::hd6f9d6d2994b98f2	@	wasm-bindgen-test_bg.wasm:0x2aa15b
$wasm_bindgen_test::__rt::Context::execute_async::{{closure}}::h656701822149525f	@	wasm-bindgen-test_bg.wasm:0x204a56
$<core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h6d304df6f7bf69ff	@	wasm-bindgen-test_bg.wasm:0x2a9e5f
$<wasm_bindgen_test::__rt::TestFuture<F> as core::future::future::Future>::poll::{{closure}}::{{closure}}::h8eb6ed72ffbe352a	@	wasm-bindgen-test_bg.wasm:0x2d7253
$wasm_bindgen::convert::closures::invoke0_mut::h2c699ce350272107	@	wasm-bindgen-test_bg.wasm:0x2bbdf1
__wbg_adapter_54	@	wasm-bindgen-test:364
cb0	@	wasm-bindgen-test:536
window.__wbg_test_invoke	@	(index):25
(anonymous)	@	wasm-bindgen-test:541
handleError	@	wasm-bindgen-test:369
imports.wbg.__wbg_wbgtestinvoke_6d22b7d64550c12f	@	wasm-bindgen-test:529
$wasm_bindgen_test::__rt::__wbg_test_invoke::h5911ea9eca5183b7	@	wasm-bindgen-test_bg.wasm:0x250c48
$<wasm_bindgen_test::__rt::TestFuture<F> as core::future::future::Future>::poll::{{closure}}::hd4695e4a25d6c3a8	@	wasm-bindgen-test_bg.wasm:0x2bd317
$scoped_tls::ScopedKey<T>::set::h711076e3a91c0bdf	@	wasm-bindgen-test_bg.wasm:0x26e371
$<wasm_bindgen_test::__rt::TestFuture<F> as core::future::future::Future>::poll::h5bba7ba7a2e0e0c9	@	wasm-bindgen-test_bg.wasm:0x17f779
$<wasm_bindgen_test::__rt::ExecuteTests as core::future::future::Future>::poll::h2174ed68299da2c2	@	wasm-bindgen-test_bg.wasm:0xed653
$wasm_bindgen_test::__rt::Context::run::{{closure}}::hc7d4368f014d2456	@	wasm-bindgen-test_bg.wasm:0x1f6e7c
$<core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h8b334f1807679992	@	wasm-bindgen-test_bg.wasm:0x27aee7
$wasm_bindgen_futures::future_to_promise::{{closure}}::{{closure}}::hf3c00e2c51b5e763	@	wasm-bindgen-test_bg.wasm:0x195533
$<core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h2c38d676517e2203	@	wasm-bindgen-test_bg.wasm:0x2aa8a8
$wasm_bindgen_futures::task::singlethread::Task::run::h8c5979b40af7554e	@	wasm-bindgen-test_bg.wasm:0x1e2236
$wasm_bindgen_futures::queue::QueueState::run_all::h2311101bcc23bb9c	@	wasm-bindgen-test_bg.wasm:0x2041aa
$wasm_bindgen_futures::queue::Queue::new::{{closure}}::h5ae3ab5cab960077	@	wasm-bindgen-test_bg.wasm:0x3089a8
$<dyn core::ops::function::FnMut<(A,)>+Output = R as wasm_bindgen::closure::WasmClosure>::describe::invoke::hed2c3548a8b32456	@	wasm-bindgen-test_bg.wasm:0x293997
__wbg_adapter_41	@	wasm-bindgen-test:268
real	@	wasm-bindgen-test:201
Promise.then (async)		
(anonymous)	@	wasm-bindgen-test:871
logError	@	wasm-bindgen-test:218
imports.wbg.__wbg_then_c2361a9d5c9a4fcb	@	wasm-bindgen-test:870
$js_sys::Promise::then::hea5fad77105c5bb9	@	wasm-bindgen-test_bg.wasm:0x301ca4
$wasm_bindgen_futures::queue::Queue::push_task::h3f6874a6247774a6	@	wasm-bindgen-test_bg.wasm:0x2383bf
$wasm_bindgen_futures::task::singlethread::Task::wake_by_ref::{{closure}}::hb50f853c0f646b13	@	wasm-bindgen-test_bg.wasm:0x336b87
$std::thread::local::LocalKey<T>::try_with::h8b1d60d0756bcecb	@	wasm-bindgen-test_bg.wasm:0x291e7b
$std::thread::local::LocalKey<T>::with::h05495a9c85e65f64	@	wasm-bindgen-test_bg.wasm:0x2fcbc2
$wasm_bindgen_futures::task::singlethread::Task::wake_by_ref::h4261b943cb25dea5	@	wasm-bindgen-test_bg.wasm:0x2a98c1
$wasm_bindgen_futures::task::singlethread::Task::spawn::h3c8b4f4db92cc819	@	wasm-bindgen-test_bg.wasm:0x1aa2c1
$wasm_bindgen_futures::spawn_local::h3b59c349ec0381ee	@	wasm-bindgen-test_bg.wasm:0x21c11f
$wasm_bindgen_futures::future_to_promise::{{closure}}::h9e2eccf3d06354e5	@	wasm-bindgen-test_bg.wasm:0x250e35
$wasm_bindgen::convert::closures::invoke2_mut::h2dfa9bf43d1cf4d1	@	wasm-bindgen-test_bg.wasm:0x27f7e5
__wbg_adapter_179	@	wasm-bindgen-test:394
cb0	@	wasm-bindgen-test:855
(anonymous)	@	wasm-bindgen-test:860
logError	@	wasm-bindgen-test:218
imports.wbg.__wbg_new_c143a4f563f78c4e	@	wasm-bindgen-test:848
$js_sys::Promise::new::h8e59a0bd4c565e98	@	wasm-bindgen-test_bg.wasm:0x2f4052
$wasm_bindgen_futures::future_to_promise::h8534f38060476630	@	wasm-bindgen-test_bg.wasm:0x27e949
$wasm_bindgen_test::__rt::Context::run::h6582b0a7dbf5ac7b	@	wasm-bindgen-test_bg.wasm:0x13a674
$wasmbindgentestcontext_run	@	wasm-bindgen-test_bg.wasm:0x254b3a
run	@	wasm-bindgen-test:467
main	@	run.js:33
async function (async)		
main	@	run.js:18
(anonymous)	@	run.js:41

bjorn3 · October 15, 2021, 1:00pm

Javascript promises require you to call .then() with a closure to indicate what should be done once the promise completes. Newer browsers helpfully keep the original promise to allow for showing a backtrace spanning from the original place the promise was created all the way up to the location producing the backtrace, even if it is part of the closure passed to .then(). Every place where it stitched stacks together is indicated with (async). I think the only way to get rid of the stack again would be to call setInterval with a 0ms duration.

system · January 13, 2022, 1:01pm

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Wasm stack trace from JsFutures

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