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Blender freezes when playhead is dragged in this .blend
Closed, ResolvedPublicBUG

Description

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce RTX 2060/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 457.30

Blender Version
Broken: version: 2.93.0 Alpha, branch: master, commit date: 2021-03-16 22:45, hash: rBde06cb85593b
Worked: blender-2.93.0-be51d671b500-windows64

Short description of error
Blender becomes unresponsive when playhead is dragged (in this .blend)

Exact steps for others to reproduce the error
Open attached .blend
Try to drag the playhead to a different frame
Blender becomes unresponsive (spinning progress cursor) before the playhead moves.

Event Timeline

I can reproduce it, but the problem is present when you remove all grease pencil objects too, so not sure if this bug is gpencil related or not.

@Falk David (filedescriptor) I can reproduce, but I cannot stop the program to see where is doing the loop.. can you try?

I cannot reproduce the issue. Scrubbing the timeline works fine for me.

System Information
Operating system: Linux-5.8.0-7642-generic-x86_64-with-glibc2.32 64 Bits
Graphics card: GeForce GTX 1060 6GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 460.56

I have tested opening the file in 2.92, removing all objects (empty file) and opening in 2.93 with the same problem.

The test file.

@Ray molenkamp (LazyDodo) If yo can, please take a look and try to find what is the problem in Windows, I'm unable to see what is going on.

It's a deadlock in the audio code.

main thread is waiting for the audio thread to join while it's holding a mutex

 	[Waiting on Thread 0xB44, double-click or press enter to switch to thread]	
 	[External Code]	
>	blender.exe!aud::WASAPIDevice::start() Line 43	C++
 	blender.exe!aud::WASAPIDevice::playing(bool playing) Line 143	C++
 	blender.exe!aud::SoftwareDevice::SoftwareHandle::resume() Line 288	C++
 	blender.exe!AUD_Handle_resume(std::shared_ptr<aud::IHandle> * handle) Line 36	C++
 	blender.exe!BKE_sound_seek_scene(Main * bmain, Scene * scene) Line 944	C
 	blender.exe!BKE_scene_update_sound(Depsgraph * depsgraph, Main * bmain) Line 2589	C
 	blender.exe!BKE_scene_graph_update_for_newframe(Depsgraph * depsgraph) Line 2723	C
 	blender.exe!ED_update_for_newframe(Main * bmain, Depsgraph * depsgraph) Line 1631	C
 	blender.exe!wm_event_do_notifiers(bContext * C) Line 538	C
 	blender.exe!WM_main(bContext * C) Line 652	C
 	blender.exe!main(int argc, const unsigned char * * UNUSED_argv_c) Line 524	C
 	[External Code]

meanwhile on the audio thread:

 	[External Code]	
 	blender.exe!aud::SoftwareDevice::lock() Line 912	C++
>	blender.exe!aud::WASAPIDevice::updateStream() Line 83	C++
 	[External Code]

it's stuck waiting for this lock

	lock();

	mix((data_t*)buffer, length);

	unlock();

deadlock ensures

Ray molenkamp (LazyDodo) changed the task status from Needs Triage to Confirmed.Mar 19 2021, 5:59 PM

If this bug bit you, you can work around the issue by selecting any other audio subsystem in the preferences but "WASAPI"

@Ray molenkamp (LazyDodo) just to get an idea of what is triggering it, could you try disabling Audio Scrubbing in the Playback Menu?

Can confirm that also sidesteps the issue.

Falk David (filedescriptor) changed the subtype of this task from "Report" to "Bug".Mar 19 2021, 6:15 PM