Godot hangs when there is a change to USB devices

[grofit]

Tested versions

• Originally happened in released game running Godot 4.3.* (Nomad Idle)
• Verified behaviour locally using Godot 4.4.1

System information

Windows 11 Pro - Godot Engine v4.4.1.stable.mono.official.49a5bc7b6 - Vulkan 1.3.302 - Forward+ - Using Device #0: AMD - AMD Radeon RX 9070

Issue description

Whenever there is an alteration of USB devices on the host system it causes Godot to hang and in some instances be unrecoverable and need manually closing. I have been unable to get a crash report as it just locks up and refuses to close and the logs show nothing, happy to get more information if someone can provide instructions on how to get info when its hung as editor is also unresponsive during this time.

In my specific scenario I am using a USB switcher to switch a wired USB Keyboard/Mouse between two host PCs, switching away from the PC running Godot is not an issue, but when I switch the USB devices back to the pc running Godot the player hangs and is often unrecoverable, I have had someone separately reproduce the hanging by plugging in a USB gamepad while a Godot game (Nomad Idle) is running, they were unable to get an unrecoverable hang, but they reported it hangs for a few seconds whenever they plug in their USB device.

There have been related issues over the years but they seem to have been marked as fixed:

• Godot Editor crashes when plugging in a controller #36266
• Game/engine crashes when (un)plugging USB headphones #17453

It is anecdotal but it seems more likely to enter an unrecoverable hang when its under more load, so I am unsure if there is some internal race condition.

Steps to reproduce

• Load Godot Editor (ideally with something moving in scene to visually see it hang)
• Run the scene
• Plug in a USB device (for me a keyboard/mouse, for others a gamepad)
• The scene in the player hangs for a second or two

If you are unable to get it to be unrecoverable try to put the scene under load and try to plug the USB device in.

Minimal reproduction project (MRP)

A fresh Godot project should show same issue

[Torguen]

I experience the same or a similar issue. When my game is running and I connect my Stadia controller via Bluetooth, before the controller becomes operational in the game, the game freezes for about 3 seconds. After that, I can use the controller.

[AThousandShips]

Can't replicate with a simple project, no stuttering at all, on 4.5.dev or 4.4.1.stable, might need a much heavier scene though, but no stuttering at all in the editor frame time either

[grofit]

I made a new scene, added a sprite, gave it a tween to make it switch between red and white and here is result:

Godot_v4.4.1-stable_mono_win64_mnVseEB06t.mp4

First few seconds I just let it go, then I switched my USB devices to other PC, it was still fine, then I switched it back and you can see it hang, become unresponsive (I move the mouse to show you the PC is still active and not frozen), then after a few seconds it resumes.

As I say in my specific scenario I have a USB switcher which is switching both keyboard and mouse, but others have reported it happens with game pads too.

[AThousandShips]

Probably hardware or driver specific then as it doesn't happen for me, can test with other hardware later and see if it changes anything

[ydeltastar]

It also hangs on me for a second or two when I connect a keyboard or mouse to a regular motherboard USB port (but not when I unplug them). Also, when I connect or disconnect a USB Bluetooth adapter for a wireless headphone.

[ydeltastar]

I did profiling and the hangs on any USB device come from

godot/platform/windows/joypad_windows.cpp

Line 369 in 7b9c512

dinput->EnumDevices(DI8DEVCLASS_GAMECTRL, enumCallback, this, DIEDFL_ATTACHEDONLY);

Funny enough, my USB XBox One gamepad makes it hang the least. It does a quick spike in FPS while other devices make it hang for longer.

[AThousandShips]

That's a good starting point! Could be an issue upstream, or a driver issue though, not sure there's anything we're doing wrong in the code here

[Zireael07]

@ydeltastar If the hang is in EnumDevices, probably related to #20566 since you're on Windows. There's a workaround buried somewhere in the huge thread