mate-hud is causing a complete input deadlock

[flexiondotorg]

@vkareh After some more thorough testing mate-hud 18.04.0 is causing a complete input lock up for keyboard and mouse.

This can be reproduced using mate-hud from git master on Ubuntu MATE 18.04 with a layout activated that uses the Global Menu, such as Mutiny, Cupertino or Contemporary. I was able to create the deadlock by invoking things that required Alt, such as Alt + PrtScn or Ctrl + Alt +t. It doesn't happen 100% of the time but after a few uses of Alt the lock up happens. The only recourse is to switch to a vt and kill mate-hud then switch back to the desktop vt.

The best way to test this is using the Ubuntu MATE 18.04 daily live image on actual hardware and replacing mate-hud with the version in git master.

Reverting this patch resolves the issue:

• 92d4fe2

So I will publish a new .deb that reverts that commit via patch for the time being 😄

[vkareh]

@flexiondotorg - I made some fixes to the code, but I still the get input deadlock ocassionally. However, it only happens when mate-hud is started along with the desktop environment. If I run mate-hud after the computer is fully booted, I don't get the input lock. I have vague memories of this being an issue for earlier iterations of mate-hud during the 17.10 dev cycle and I think I remember you changing where/when in the boot process it gets loaded. Could it be related?

[flexiondotorg]

@vkareh I've been making some unrelated changes to mate-hud this morning and managed to encounter a deadlock, the was output to stdout just before the lock up happened:

<class 'Xlib.error.BadAccess'>: code = 10, resource_id = 518, sequence_number = 22, major_opcode = 28, minor_opcode = 0

[flexiondotorg]

@vkareh I may have found a solution. I will test over the coming days to confirm. Looks like it may not be a mate-hud issue.

[flexiondotorg]

Sadly I was wrong, the lockups still happen.

[vkareh]

@flexiondotorg - damn, I was both curious and hopeful for a while there. No worries, the BadAccess error is actually quite helpful! I'll work on a fix this week - this issue has been driving me insane!!

[flexiondotorg]

@vkareh I'm using the new release with the potential lock-up fix, sadly I just experienced a lock up. I run Compiz so I am now testing to Marco to see if that is a factor.

[flexiondotorg]

Locked up with Marco too.

[vkareh]

Yeah, same experience here. However, if I start it directly from the command line after the desktop is fully up, I don't get the locks... :/

[flexiondotorg]

I'm still experiencing lock ups with d4d57e4 applied. I'll test with the Whitelist Caja navigation shortcuts change applied.

[vkareh]

Okay, back to the drawing board :/

[flexiondotorg]

Two hours of mate-hud being active with #21 applied. No lock ups so far...

[flexiondotorg]

Just had a lock up.

[vkareh]

I'm testing extra checks, like wrapping the entire keybinding processing block in try/catch and call allow_events if it ever fails - I'll test more on my side to see what happens...

Did #21 solve the caja navigation for you?

[flexiondotorg]

Yes, #21 solved Caja navigation as best as I can tell. I've never used those keybindings in Caja before.

[vkareh]

I haven't gotten an input lock up since the try-catch update. Have you? We should maybe keep this issue open for a little while longer, but I'm really looking forward to when we can close it!! :) :)

[flexiondotorg]

I have not. HUD is disabled by default, but the fix is released to Ubuntu. I'm thinking leave HUD disabled by default. Your thoughts?

[vkareh]

I think we should leave it off by default. It decreases the chances of any remaining issues for users that don't want/need/expect the HUD. Mutiny should have it on, of course, as that's part of the overall experience, but other than that I think users that really want it will know to enable it.

[flexiondotorg]

I've not experienced a lock up for nearly two weeks on multiple computers.

[jonpolak]

Happening again on 23.04 (Ubuntu Mate). Same issues, using Alt a few times in combination with other keys. Killing rofi (the display agent called by mate-hub) solved the issue.