Using wgpu with GLFW causes system freeze on window close

[caelunshun]

Description
A wgpu application using GLFW instead of winit will occasionally hang my system for ~10 seconds when shutting down. The issue also happens with minifb, and possibly other window management crates.

Additionally, resizing the window freezes the application, and the whole system hangs when I kill the process.

Possibly related to #318, except changing the present mode does not solve the problem.

Repro steps
Run the hello-triangle example ported to GLFW: source here. Then terminate the process with ctrl-C.

Platform
Ubuntu 18.04 running an NVIDIA GPU with driver version 460. The issue happens on the master branch as well as versions 0.9, 0.8, and 0.7. I haven't tested further back.

[cwfitzgerald]

Is there any way to test where it is hanging? If this is also happening with minifb, this feels like an issue at another layer in the stack (maybe glfw).

[caelunshun]

Here's the stacktrace in a debugger:

[cwfitzgerald]

So it seems we're literally just waiting for the gpu to finish whatever it is doing. I'm not sure what we can do about that 🤔

[kvark]

I think this particular wait isn't really needed, since we are at the end of destruction clean-up, and we waited previously before starting it. But it is also deep in the stack (in wgpu-hal/vulkan), and it should be totally valid to do as long as the Vulkan device is not corrupted. Not sure what to do about this.

@caelunshun do you hook up env_logger? I wonder if Vulkan validation says anything.

[caelunshun]

do you hook up env_logger? I wonder if Vulkan validation says anything.

No validation errors in the logs—the last message that gets printed is

[2021-07-03T20:55:50Z INFO  wgpu_core::hub] Dropping Global

before the program hangs.

[kvark]

Maybe we are trying to destroy the surface, and GLFW has already deleted the window our surface was created from.
This is related to the concept of Window/Surface API safety - #1463

[teoxoy]

It has been some time, @caelunshun is this still an issue?

[Wumpf]

closing as stale.
Please re-open if more information surfaces