"Uncaught (in promise) unwind" error from wgpuInstanceWaitAny for wgpuBufferMapAsync future

[fridenmf]

Version of emscripten/emsdk:

emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 4.0.7 (8dc91db45bf96c174531006839472a3924d105aa)
clang version 21.0.0git (https:/github.com/llvm/llvm-project 57025b42c43b2f14f7e58692bc19cd53d1b8a45e)
Target: wasm32-unknown-emscripten
Thread model: posix

Full link command and output with -v appended:

[100%] Linking CXX executable my_app.js
cd /home/my_user/repos/my_solution/out/my_app && /usr/bin/cmake -E cmake_link_script CMakeFiles/my_app.dir/link.txt --verbose=1
/home/my_user/repos/emsdk/upstream/emscripten/em++ -sWASM=1 -sUSE_WEBGPU=0 -sASYNCIFY=1 --use-port=/home/my_user/repos/my_solution/my_project/external/emscripten_ports/emdawnwebgpu.py --closure-args=--externs=/home/my_user/repos/emsdk/upstream/emscripten/cache/ports/emdawnwebgpu/emdawnwebgpu_pkg/webgpu/src/webgpu-externs.js @CMakeFiles/my_app.dir/objects1.rsp -o my_app.js @CMakeFiles/my_app.dir/linkLibs.rsp
gmake[2]: Leaving directory '/home/my_user/repos/my_solution/out'
[100%] Built target my_app
gmake[1]: Leaving directory '/home/my_user/repos/my_solution/out'
/usr/bin/cmake -E cmake_progress_start /home/my_user/repos/my_solution/out/CMakeFiles 0

Browser:
Google Chrome: Version 136.0.7103.0 (Official Build) canary (64-bit)

TLDR Browser console output:

my_app.html:46 [my_app] Calling wgpuInstanceWaitAny for wgpuBufferMapAsync future with timeout 1'500'000'000ull...
my_app.html:1 Uncaught (in promise) unwind
    Promise.then		
    (anonymous)	@	my_app.js:6457
    handleSleep	@	my_app.js:6374
    handleAsync	@	my_app.js:6455
    _emwgpuWaitAny	@	my_app.js:5239
    imports.<computed>	@	my_app.js:6225
    $EventManager::WaitAny(unsigned long long, unsigned long, WGPUFutureWaitInfo*, unsigned long long)	@	webgpu.cpp:530
    $WGPUInstanceImpl::WaitAny(unsigned long, WGPUFutureWaitInfo*, unsigned long long)	@	webgpu.cpp:1572
    $wgpuInstanceWaitAny	@	webgpu.cpp:1902

Full Browser console output:

Expand

[C/C++ DevTools Support (DWARF)] Loading debug symbols for http://localhost:6931/my_app.wasm...
my_app.html:46 [my_app] Calling wgpuCreateInstance...
my_app.html:46 [my_app] Called wgpuCreateInstance
my_app.html:46 [my_app] Called wgpuInstanceCreateSurface
my_app.html:46 [my_app] Calling wgpuInstanceRequestAdapter...
my_app.js:5189 WebGPU is experimental on this platform. See https://github.com/gpuweb/gpuweb/wiki/Implementation-Status#implementation-status
my_app.html:46 [my_app] Called wgpuInstanceRequestAdapter
my_app.html:46 [my_app] Calling wgpuInstanceWaitAny for wgpuInstanceRequestAdapter future with timeout 1'500'000'000ull...
[C/C++ DevTools Support (DWARF)] Loaded debug symbols for http://localhost:6931/my_app.wasm, found 872 source file(s)
my_app.html:46 [my_app] WGPURequestAdapterStatus: WGPURequestAdapterStatus_Success
my_app.html:46 [my_app] WGPUWaitStatus: WGPUWaitStatus_Success
my_app.html:46 [my_app] Setting only WGPUFeatureName_IndirectFirstInstance as required feature
my_app.html:46 [my_app] Setting supported limits as required limits
my_app.html:46 [my_app] Called wgpuAdapterRequestDevice
my_app.html:46 [my_app] Calling wgpuInstanceWaitAny for wgpuAdapterRequestDevice future with timeout 1'500'000'000ull...
my_app.html:46 [my_app] WGPURequestDeviceStatus: WGPURequestDeviceStatus_Success
my_app.html:46 [my_app] WGPUWaitStatus: WGPUWaitStatus_Success
my_app.html:46 [my_app] Called wgpuDeviceGetQueue
my_app.html:46 [my_app] Calling emscripten_request_animation_frame_loop...
my_app.html:46 [my_app] Called emscripten_request_animation_frame_loop
my_app.html:46 [my_app] Calling emscripten_exit_with_live_runtime...
my_app.html:46 [my_app] In onAnimationFrame...
my_app.html:46 [my_app] Created WGPUTexture 336576 (with format WGPUTextureFormat_BGRA8Unorm, sampleCount 1, usage (WGPUTextureUsage_CopySrc | WGPUTextureUsage_RenderAttachment)
my_app.html:46 [my_app] Created WGPUTextureView 336600 for texture 336576
my_app.html:46 [my_app] Called wgpuTextureSetLabel for WGPUTexture 336576 with label "Color RenderAttachment image 0"
my_app.html:46 [my_app] Called wgpuTextureViewSetLabel for WGPUTextureView 336600 with label "Color RenderAttachment image 0 (View)"
my_app.html:46 [my_app] WGPUSurfaceGetCurrentTextureStatus: SuccessOptimal
my_app.html:46 [my_app] Got WGPUTexture 337136 from wgpuSurfaceGetCurrentTexture with format WGPUTextureFormat_BGRA8Unorm, usage (WGPUTextureUsage_CopyDst | WGPUTextureUsage_RenderAttachment)
my_app.html:46 [my_app] Created WGPUTextureView 337160 for texture 337136 with format WGPUTextureFormat_BGRA8Unorm, usage: (WGPUTextureUsage_CopyDst | WGPUTextureUsage_RenderAttachment)
my_app.html:46 [my_app] Called wgpuTextureSetLabel for WGPUTexture 337136 with label "Swapchain image 0"
my_app.html:46 [my_app] Called wgpuTextureViewSetLabel for WGPUTextureView 337160 with label "Swapchain image 0 (View)"
my_app.html:46 [my_app] Created WGPUBuffer 338304 with usage (WGPUBufferUsage_CopyDst | WGPUBufferUsage_Vertex)
my_app.html:46 [my_app] Created WGPUBuffer 338376 with usage (WGPUBufferUsage_CopyDst | WGPUBufferUsage_Index)
my_app.html:46 [my_app] Created WGPUBuffer 338480 with usage (WGPUBufferUsage_CopyDst | WGPUBufferUsage_Storage)
my_app.html:46 [my_app] Created WGPUBuffer 331128 with usage (WGPUBufferUsage_CopyDst | WGPUBufferUsage_Storage)
my_app.html:46 [my_app] Created WGPUBuffer 330304 with usage (WGPUBufferUsage_CopyDst | WGPUBufferUsage_Indirect)
my_app.html:46 [my_app] Created WGPUBuffer 330408 with usage (WGPUBufferUsage_MapWrite | WGPUBufferUsage_CopySrc)
my_app.html:46 [my_app] Created WGPUTexture 338584 (with format WGPUTextureFormat_RGBA8Unorm, sampleCount 1, usage (WGPUTextureUsage_CopyDst | WGPUTextureUsage_TextureBinding)
my_app.html:46 [my_app] Created WGPUTextureView 338608 for texture 338584
my_app.html:46 [my_app] Created WGPUTexture 338632 (with format WGPUTextureFormat_RGBA8Unorm, sampleCount 1, usage (WGPUTextureUsage_CopyDst | WGPUTextureUsage_TextureBinding)
my_app.html:46 [my_app] Created WGPUTextureView 331200 for texture 338632
my_app.html:46 [my_app] Called wgpuTextureSetLabel for WGPUTexture 338584 with label "Background TextureBinding image 0"
my_app.html:46 [my_app] Called wgpuTextureViewSetLabel for WGPUTextureView 338608 with label "Background TextureBinding image 0 (View)"
my_app.html:46 [my_app] Called wgpuTextureSetLabel for WGPUTexture 338632 with label "Sprite TextureBinding image 0"
my_app.html:46 [my_app] Called wgpuTextureViewSetLabel for WGPUTextureView 331200 with label "Sprite TextureBinding image 0 (View)"
my_app.html:46 [my_app] Calling wgpuBufferMapAsync for buffer 330408...
my_app.html:46 [my_app] Called wgpuBufferMapAsync
my_app.html:46 [my_app] Calling wgpuInstanceWaitAny for wgpuBufferMapAsync future with timeout 1'500'000'000ull...
my_app.html:1 Uncaught (in promise) unwind
    Promise.then		
    (anonymous)	@	my_app.js:6457
    handleSleep	@	my_app.js:6374
    handleAsync	@	my_app.js:6455
    _emwgpuWaitAny	@	my_app.js:5239
    imports.<computed>	@	my_app.js:6225
    $EventManager::WaitAny(unsigned long long, unsigned long, WGPUFutureWaitInfo*, unsigned long long)	@	webgpu.cpp:530
    $WGPUInstanceImpl::WaitAny(unsigned long, WGPUFutureWaitInfo*, unsigned long long)	@	webgpu.cpp:1572
    $wgpuInstanceWaitAny	@	webgpu.cpp:1902
    $my_namespace::webgpu::waitAny(WGPUInstanceImpl*, my_namespace::webgpu::DeviceProcs&, WGPUFuture, std::__2::basic_string_view<char, std::__2::char_traits<char>>)	@	my_lib_webgpu.cpp:1368
    $my_namespace::webgpu::requestDevice(WGPUInstanceImpl*, my_namespace::webgpu::DeviceProcs&, WGPUAdapterImpl*, my_namespace::webgpu::Log&, State&)	@	my_lib_webgpu.cpp:2113
    $my_namespace::webgpu::requestDevice(Instance, Surface*, unsigned long long)	@	my_lib_webgpu.cpp:2174
    $my_namespace::Instance::requestDevice(my_namespace::Surface const*, unsigned long long)	@	my_lib_webgpu.hpp:985
    $my_namespace::test::test(my_namespace::State&&)	@	my_app.cpp:2985
    $__original_main	@	my_app_main.cpp:21
    $main	@	my_app.wasm:0x4b4acc
    ret.<computed>	@	my_app.js:6257
    doRewind	@	my_app.js:6362
    (anonymous)	@	my_app.js:6396
    Promise.then		
    (anonymous)	@	my_app.js:6457
    handleSleep	@	my_app.js:6374
    handleAsync	@	my_app.js:6455
    _emwgpuWaitAny	@	my_app.js:5239
    imports.<computed>	@	my_app.js:6225
    $EventManager::WaitAny(unsigned long long, unsigned long, WGPUFutureWaitInfo*, unsigned long long)	@	webgpu.cpp:530
    $WGPUInstanceImpl::WaitAny(unsigned long, WGPUFutureWaitInfo*, unsigned long long)	@	webgpu.cpp:1572
    $wgpuInstanceWaitAny	@	webgpu.cpp:1902
    $my_namespace::webgpu::waitAny(WGPUInstanceImpl*, my_namespace::webgpu::DeviceProcs&, WGPUFuture, std::__2::basic_string_view<char, std::__2::char_traits<char>>)	@	my_lib_webgpu.cpp:1368
    $my_namespace::webgpu::requestAdapter(WGPUInstanceImpl*, WGPUSurfaceImpl*, my_namespace::webgpu::DeviceProcs&, my_namespace::webgpu::Log&)	@	my_lib_webgpu.cpp:1491
    $my_namespace::webgpu::requestDevice(Instance, Surface*, unsigned long long)	@	my_lib_webgpu.cpp:2172
    $my_namespace::Instance::requestDevice(my_namespace::Surface const*, unsigned long long)	@	my_lib_webgpu.hpp:985
    $my_namespace::test::test(my_namespace::State&&)	@	my_app.cpp:2985
    $__original_main	@	my_app_main.cpp:21
    $main	@	my_app.wasm:0x4b4acc
    ret.<computed>	@	my_app.js:6257
    (anonymous)	@	my_app.js:635
    callMain	@	my_app.js:7206
    doRun	@	my_app.js:7259
    run	@	my_app.js:7272
    removeRunDependency	@	my_app.js:586
    receiveInstance	@	my_app.js:745
    receiveInstantiationResult	@	my_app.js:763
    createWasm	@	my_app.js:789
    await in createWasm		
    (anonymous)
my_app.html:46 [my_app] WGPUMapAsyncStatus: WGPUMapAsyncStatus_Success
my_app.html:46 [my_app] WGPUWaitStatus: WGPUWaitStatus_Success
my_app.html:46 [my_app] Created WGPUBuffer 331696 with usage (WGPUBufferUsage_CopyDst | WGPUBufferUsage_Vertex)
my_app.html:46 [my_app] Created WGPUBuffer 333624 with usage (WGPUBufferUsage_CopyDst | WGPUBufferUsage_Index)
my_app.html:46 [my_app] Created WGPUBuffer 333728 with usage (WGPUBufferUsage_CopyDst | WGPUBufferUsage_Storage)
my_app.html:46 [my_app] Created WGPUBuffer 333832 with usage (WGPUBufferUsage_CopyDst | WGPUBufferUsage_Storage)
my_app.html:46 [my_app] Created WGPUBuffer 333936 with usage (WGPUBufferUsage_CopyDst | WGPUBufferUsage_Indirect)
my_app.html:46 [my_app] Created WGPUBuffer 334040 with usage (WGPUBufferUsage_MapWrite | WGPUBufferUsage_CopySrc)
my_app.html:46 [my_app] Created WGPUTexture 334144 (with format WGPUTextureFormat_RGBA8Unorm, sampleCount 1, usage (WGPUTextureUsage_CopyDst | WGPUTextureUsage_TextureBinding)
my_app.html:46 [my_app] Created WGPUTextureView 334168 for texture 334144
my_app.html:46 [my_app] Calling wgpuBufferMapAsync for buffer 334040...
my_app.html:46 [my_app] Called wgpuBufferMapAsync
my_app.html:46 [my_app] Calling wgpuInstanceWaitAny for wgpuBufferMapAsync future with timeout 1'500'000'000ull...
my_app.html:46 [my_app] WGPUMapAsyncStatus: WGPUMapAsyncStatus_Success
my_app.html:46 [my_app] WGPUWaitStatus: WGPUWaitStatus_Success
my_app.html:46 [my_app] Calling wgpuCommandEncoderBeginRenderPass...
my_app.html:46 [my_app] Called wgpuCommandEncoderBeginRenderPass
my_app.html:46 [my_app] Calling wgpuRenderPassEncoderEnd...
my_app.html:46 [my_app] Called wgpuRenderPassEncoderEnd
my_app.html:46 [my_app] Calling wgpuCommandEncoderCopyTextureToTexture from (Color RenderAttachment image 0) to (Swapchain image 0)...
my_app.html:46 [my_app] Called wgpuCommandEncoderCopyTextureToTexture
my_app.html:46 [my_app] Calling wgpuCommandEncoderFinish...
my_app.html:46 [my_app] Called wgpuCommandEncoderFinish
my_app.html:46 [my_app] Calling wgpuQueueSubmit...
my_app.html:46 [my_app] Called wgpuQueueSubmit
my_app.html:46 [my_app] Calling wgpuQueueOnSubmittedWorkDone...
my_app.html:46 [my_app] Called wgpuQueueOnSubmittedWorkDone
[my_app] WGPUUncapturedErrorCallback got WGPUErrorType_Validation (Destroyed texture [Texture "Swapchain image 0"] used in a submit.
my_app.html:46  - While calling [Queue].Submit([[CommandBuffer]])
my_app.html:46 )

There is a few things I don't understand here:

1. When looking at the full browser console output, the stacktrace leading up to the "Uncaught (in promise) unwind" is not from the wgpuInstanceWaitAny for the wgpuBufferMapAsync future as I would have expected, it's from a call to wgpuInstanceWaitAny for the future from wgpuAdapterRequestDevice. As seen earlier in the log the wgpuInstanceWaitAny has already completed for that future with status WGPUWaitStatus_Success, and it's WGPURequestDeviceStatus was WGPURequestDeviceStatus_Success.
2. The wgpuInstanceWaitAny for the future of wgpuBufferMapAsync do complete with status WGPUWaitStatus_Success and WGPUMapAsyncStatus_Success dispite the "Uncaught (in promise) unwind", and I'm later able to call wgpuBufferMapAsync for another buffer which completes successfully without any "Uncaught (in promise) unwind".
3. From the perspective of WebGPU, all functions return the expected successful statuses until the end of the frame where I'm calling wgpuQueueOnSubmittedWorkDone before returning from the emscripten_request_animation_frame_loop callback, but I get a WGPUUncapturedErrorCallback validation error "Destroyed texture [Texture "Swapchain image 0"] used in a submit.", even though I've not released any textures or texture views at this point.

From my perspective, the WebGPU code returns all the expected success return statuses, and the code do work for Dawn on Windows, but I don't know how to prevent the swapchain image from being released since it's not me doing that.

So I guess it's more relevant to focus on the "Uncaught (in promise) unwind" since it happens before that, with a JS stacktrace which already has a successful status on the C++ side.

Could I get help from someone with more insight in the JS machinery behind the wgpuInstanceWaitAny/ASYNCIFY parts on how to proceed here?

As seen in the full link commands, I'm using the emdawnwebgpu port from:
#23432

[kainino0x]

Thank you for the report! Since this is emdawnwebgpu, I'm moving it to Dawn's bugtracker: https://crbug.com/412395833
Please +1 that and comment there.

[kainino0x]

I've replied there: https://crbug.com/412395833#comment2

[fridenmf]

Move to Dawn's bugtracker

Just to clarify, as I wrote above, running Dawn natively on Windows works fine (built from the same revision d0390759). It's just when running in a browser in an emscripten build that things doesn't work.

Anyways, I don't have a suitable Google account to be able to interact in the Dawn bugtracker, I'm limited to use this Github account, so I'll respond to your questions here for now.

JSPI

I rebuilt the application with -sASYNCIFY=2

[100%] Linking CXX executable my_app.js
cd /home/my_user/repos/my_solution/out/my_app && /usr/bin/cmake -E cmake_link_script CMakeFiles/my_app.dir/link.txt --verbose=1
/home/my_user/repos/emsdk/upstream/emscripten/em++ -sWASM=1 -sUSE_WEBGPU=0 -sASYNCIFY=2 --use-port=/home/my_user/repos/my_solution/my_project/external/emscripten_ports/emdawnwebgpu.py --closure-args=--externs=/home/my_user/repos/emsdk/upstream/emscripten/cache/ports/emdawnwebgpu/emdawnwebgpu_pkg/webgpu/src/webgpu-externs.js @CMakeFiles/my_app.dir/objects1.rsp -o my_app.js @CMakeFiles/my_app.dir/linkLibs.rsp
em++: warning: -sASYNCIFY=2 (JSPI) is still experimental [-Wexperimental]
gmake[2]: Leaving directory '/home/my_user/repos/my_solution/out'
[100%] Built target my_app

And then set chrome://flags/#enable-experimental-webassembly-jspi in the browser, restarted, but I get another runtime error instead:

[my_app] Calling wgpuInstanceWaitAny for wgpuBufferMapAsync future with timeout 1'500'000'000ull...
my_app.html:62 [Error] Uncaught SuspendError: trying to suspend without WebAssembly.promising
	window.onerror	@	my_app.html:62
    requestAnimationFrame		
    _emscripten_request_animation_frame_loop	@	my_app.js:4042
    $func798	@	my_app.wasm:0x399e3
    $func989	@	my_app.wasm:0x422f1
    $func1045	@	my_app.wasm:0x447a9
    $func4753	@	my_app.wasm:0x1cde6a
    $main	@	my_app.wasm:0x1cde8d

RequestAdapter callback

I'm just appending a string in the callback, and getting the adapter if WGPURequestAdapterStatus_Success:

auto wgpuRequestAdapterCallback = [](
    WGPURequestAdapterStatus status,
    WGPUAdapter adapter,
    WGPUStringView message,
    void* userdata1,
    void* userdata2)
{
    auto& logStr = ((Log*)userdata2)->logStr;

    logStr += std::format("WGPURequestAdapterStatus: {}\n", showWGPURequestAdapterStatus(status));

    if (message.length > 0)
        logStr += std::format("WGPURequestAdapterStatus: {}\n", std::string(message.data, message.length));

    if (status == WGPURequestAdapterStatus_Success)
        *(WGPUAdapter*)userdata1 = adapter;
};

I always get status WGPURequestAdapterStatus_Success when running, and I always get a non null adapter out of it, after a wgpuInstanceWaitAny with wait status WGPUWaitStatus_Success.

Port version

I'm using ypujante's "compliant" port with this version:
https://github.com/kainino0x/dawn/releases/tag/v2025.04.12-03.06.48

I removed the script from ypujante, unpacked the v2025.04.12-03.06.48 release and followed the instructions from the readme, and rebuilt the application. Unfortunately I always get the same result, the -sASYNCIFY=1 get the Uncaught (in promise) unwind and Destroyed texture [Texture "Swapchain image 0"] used in a submit. validation error, and -sASYNCIFY=2 get Uncaught SuspendError: trying to suspend without WebAssembly.promising.

I also tried the rest of the releases with the same result for both -sASYNCIFY=1 and -sASYNCIFY=2:
https://github.com/kainino0x/dawn/releases/tag/v20250415.221817-kainino0x.dawn.main
https://github.com/kainino0x/dawn/releases/tag/v20250416.175657-kainino0x.dawn.main
https://github.com/kainino0x/dawn/releases/tag/v20250418.112711-kainino0x.dawn.main

Repro case

The application I'm porting is implementing a separate lib a graphics api independent header for which one of the backends is WebGPU, which is then used in a lib that does the higher level graphics logic, which is then used in an application which has all the test data. I'm not able to share this code. Porting the current Vulkan backend to WebGPU to run on Windows using Dawn took about a day and it works very well, but we've been at it for several weeks just to get the already working WebGPU code running in a browser. It would take a while for us to reproduce this outside the existing code base.

Is there no way to get more feedback from Emscripten/emdawnwebgpu on what's going wrong here so that we that we can progress here? From the perspective of a "native C++ user" point of view it's very confusing that all return codes from the WebGPU is successful up until the very final submit, but something has apparently gone wrong on the JS side before that, so I don't know how to progress from here.

I'm available on the WebAssembly/emscripten Discord for a screen share if we can't get anywhere else, given that none of the information from my screen is shared in any way without my concent, if it helps.

[kainino0x]

Just to clarify, as I wrote above, running Dawn natively on Windows works fine (built from the same revision d0390759). It's just when running in a browser in an emscripten build that things doesn't work.

Yup, we're just tracking bugs in Dawn because the code lives in the Dawn repo now.

Anyways, I don't have a suitable Google account to be able to interact in the Dawn bugtracker, I'm limited to use this Github account, so I'll respond to your questions here for now.

Sorry about that! GitHub is fine.

my_app.html:62 [Error] Uncaught SuspendError: trying to suspend without WebAssembly.promising

I've definitely seen this before, I think it's the same root cause as the Asyncify error.

Is there no way to get more feedback from Emscripten/emdawnwebgpu on what's going wrong here so that we that we can progress here? From the perspective of a "native C++ user" point of view it's very confusing that all return codes from the WebGPU is successful up until the very final submit, but something has apparently gone wrong on the JS side before that, so I don't know how to progress from here.

Hopefully this is our bug, so once we fix it people won't run into it anymore. If not, then we should figure out how to surface a better error for sure.

[fridenmf]

The very last error message in the full log of this case (Destroyed texture [Texture "Swapchain image 0"] used in a submit.) is probably related to this case:
#20839

[kainino0x]

The very last error message in the full log of this case (Destroyed texture [Texture "Swapchain image 0"] used in a submit.) is probably related to this case:
#20839

Yes, but that's expected behavior. If there's any await bubble between getCurrentTexture() and rendering to the texture, that happens. I do have some thoughts about it on the Dawn bug though.

my_app.html:62 [Error] Uncaught SuspendError: trying to suspend without WebAssembly.promising

I've definitely seen this before, I think it's the same root cause as the Asyncify error.

Oh, I should have just Googled this. It took me straight to my previous notes on the topic:
#22493 (comment)
Let me edit that so it has the non-JSPI error too, and link this bug to that one.

[kainino0x]

I'm actually not certain that the Uncaught (in promise) unwind has the same root cause, though I think it's likely. If you fix the async problem (either by removing the async operation from the frame loop, or by using that workaround, or by otherwise avoiding Emscripten's library functions for main loops), let me know if it fixes that.

[fridenmf]

either by removing the async operation from the frame loop

This is unfortunately not possible due to the nature of the ported application, we are depending on the mapAsync function from WebGPU being called from the frame loop.

or by using that workaround

I've tried the workaround using EM_ASM to create a requestAnimationFrame loop based on https://github.com/kainino0x/webgpu-cross-platform-demo/blob/c26ea3e29ed9f73f9b39bddf7964b482ce3c6964/main.cpp#L737-L758 instead of calling emscripten_request_animation_frame_loop, looking like this:

EM_ASM({
	var callback = () => globalThis['Module']['ccall']("frame", "boolean", ["number"], [$1], {async: true});
	async function tick() {
		var keepLooping = await callback();
		if (keepLooping)
			requestAnimationFrame(tick);
	}
	requestAnimationFrame(tick);
}, frame, (void*)userData);

, where the "frame" function always returns true, but I still get the same "Uncaught (in promise) unwind" error.

or by otherwise avoiding Emscripten's library functions for main loops

Is the workaround above avoiding this, or is there something else I can try here?

[fridenmf]

@kainino0x This case is still marked as duplicate even though the workaround in the other case (#22493) does not work for me, and it's Chromium counterpart (https://issues.chromium.org/issues/412395833) is marked as obsolete, does this mean this won't be fixed? I'm afraid my question in my last message will be forgotten if the cases are closed before the issues are fixed, can at least one of them be kept open until a workaround has been found or been fixed?

[kainino0x]

Apologies I forgot about this. I've reopened https://crbug.com/412395833