GUI freezes when closing application launched in disposable VM using application close button

[tonsilware]

Qubes OS version:

R3.2

Affected TemplateVMs:

All

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Steps to reproduce the behavior:

1. Run QubesOs R3.2 on a system with a dual socket Intel S2600CP2J Motherboard, 2 x E5-2670 Xeon Processors, 128GB Registered DDR3 ECC memory and an AMD graphics card.
2. Launch an application in a disposable VM (e.g. xterm or firefox).
3. Close the application that was just launched by clicking the close icon of the application.

Expected behavior:

The desktop shouldn't freeze or stutter at all while the disposable VM is terminated.

Actual behavior:

The entire desktop (including the mouse) freezes for between 0-5 seconds while Qubes cleans up/terminates the disposable VM.

General notes:

This freezing/stuttering of the GUI doesn't happen if the disposable VM is shutdown using the "Shutdown VM" menu option in the Qubes VM Manager, nor does it seem to happen if the disposable VM is shutdown by executing the "shutdown" command directly in the disposable VM. It seems to only occur if the application that was launched in the disposable VM is terminated using the close icon.

I haven't experienced this issue with QubesOs on my other less powerful systems, I'm not sure why this dual Xeon system is experiencing this issue. I've tried two different SSDs, two different AMD graphics cards, different BIOS settings etc (NUMA, Hyperthreading etc), but the issue remains.

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Related issues:

[tonsilware]

The issue seems to have been resolved in QubesOS version 4.0.

[tonsilware]

The issue seems to have been resolved in QubesOS version 4.0.