WindowServer freezes for a few seconds when BetterDisplay is open

[PuzzledUser]

Reading #3154 got me thinking. For some time I've noticed my UI will randomly freeze (like described in https://apple.stackexchange.com/questions/407774/my-macs-ui-is-randomly-freezing-for-5-10-seconds-throughout-the-day-how-can-i). I've been ignoring it for a while.

However, I realised that it only does it when BetterDisplay is running. I never see it when it's not running. When it happens, I might see the UI freeze (mouse pointer still moves) for a few (5-7 ish) seconds. It just did it whilst editing that line of text.

Now for more info and stuff that will offer hope to tie it down, but ultimately just create more uncertainty. I tried various older versions to see when the issue began. Bear in mind I can't reproduce the effect on demand; it might take 5 minutes for it to happen, sometimes it happens several times a minute. Quitting BetterDisplay brings instant relief.

Over the last few days I tested V2.3.9, 2.3.4, 2.3.0, 2.2.0, 2.0.7 and then went back to 1.4.15. All show the issue, I didn't expect that. It is maybe more common in 2.3.9, but I don't have a quantitive test to count/log the occurrences. A ping in local Terminal doesn't show any glitch when the freeze happens. I haven't noticed anything in Console logs. I don't know of a test that logs UI responsiveness to narrow this down.

Any ideas how to track this down? I've run a couple of Samples of WindowServer after a freeze, but that didn't include the string better.

I'm a Mac mini M2 24GB 1TB, Sonoma 14.5 (23F79), plus Studio Display. I typically use one dummy of 960x720. Sometimes I run PiP, but not always and it makes no difference. I used to use a 5k iMac from 2014, it didn't have this issue.

[PuzzledUser]

I just did two more tests:

1. Restarted with not opening previous windows (and with BetterDisplay set to auto launch) and when Finder appeared I found scrolling my List view Applications folder sluggish with some long freezes.
2. Restarted with BetterDisplay set to not autolaunch and found everything silky smooth.

Clearly I must be in the minority here otherwise there'd be uproar. But help would be appreciated.

[waydabber]

Uhh. Something is probably wrong, but had no such feedback about the app so far.

I had various random UI freeze issue with Macs I owned over the years for unknown reasons now and then, could was always a pain to pinpoint an issue like this, so I understand how frustrating this can be. The problem went after away a while for whatever reason. All I could do is start console logging and see if there is anything that might cause this issue and work from that (but you already did that and found nothing).

If it happens only when BetterDisplay is running, it is an obvious indicator that it has something to do with some displays. :) BetterDisplay should not be doing anything constantly particular in a background process that should cause an issue like this but uses some stuff (like queries displays, display configuration dictionaries etc) which are normal things to do - however if there is an issue with the WindowServer configuration it can trigger a who knows what kind of glitch.

You can try starting BetterDisplay with logging from Terminal and see if there is anything the app itself is doing (maybe for any reason it's in an endless reconfiguration cycle or something):

/Applications/BetterDisplay.app/Contents/MacOS/BetterDisplay -v

I assume you tried resetting the app to see if a baseline app installation has this issue.

You might also want to try to reset the WindowServer configuration files or if you want to go deep, try if the issue arises with a new install (on a secondary APFS volume, it's a quick thing to try) to see if it's a hardware config induced issue or something else. You might also want to try MonitorControl or some other display management apps to see if there is a similar issue.

[waydabber]

Note: I'll move this to discussions, but if there is a bug or some problem that is actionable, I'll open a specific Issue for that.

[waydabber]

Note: this is how you can reset the app:

Here is a step-by-step for a more thorough reset:

https://github.com/waydabber/BetterDisplay/wiki/Safe-mode,-app-reset,-app-removal#exhaustive-reset

Let me know if there is any change!

[PuzzledUser]

Aha, just saw your reset instructions after I improvised. I set aside pro.betterdisplay.BetterDisplay.plist from my Preferences folder. That seemed to reset the app!

Interestingly, it also seems to have cured the problem! Thank you!

I now have a shiny new 182 line plist, compared to my Mac-breaking 896 line monster. I'm sad to have lost my settings (there were many initially annoying things I'd customised in there), but pleased to have a non-freezing UI!

Thanks for that pointer. Oddly (to me), restoring my previous 20k plist doesn't work, as it's overwritten to a 4k file when I next launch BetterDisplay. I wanted to try the reset idea on my previous settings. 😢

[waydabber]

It's ok, thank you, I'll try to convert the plist to work on my system and see if I can reproduce the issue. If it happens again as you set up the new config, please let me know!

[PuzzledUser]

OK, The issue has recurred with a fresh plist. I left the application open and idle with default configuration for a few days; I didn't need to use a dummy. I noticed no freezes. Then an hour ago I bit the bullet and created a new dummy and adjusted a few settings. Quite quickly I noticed the freeze was back. 🙁

It's subjective, but it doesn't seem as frequent as before. It maybe provoked by PowerPoint in presentation mode with PiP active (my use case), but freezes continue after exiting presentation mode (and separately also ending PiP). Quitting PowerPoint later does not stop the freezes. It's very hard to tie down, as it is easy to miss a freeze if you are not actively typing or scrolling (It just froze twice in that one sentence, but not again for a few minutes).

This plist (redacted and attached) is much shorter (8kB), so has less accumulated clutter.
pro.betterdisplay.BetterDisplay.plist.zip

I haven't (yet) tried any of the debug steps from the last paragraph of: #3161 (comment)

Next I will try a reset and make one dummy and leave everything else vanilla.

[waydabber]

So this happens only when a virtual screen is active and you are using a PiP window?

[PuzzledUser]

For one hour now I have not noticed a freeze. This is with a fresh reset BetterDisplay running with one dummy active. I have just started a default PiP of the dummy (Normal Window Priority, not Keep Above Other Windows as I normally use) and will use my Mac for a while and see if I see a freeze...

[PuzzledUser]

OK, so maybe it was the Reset App Settings... that fixed it??
Yet I already had a virgin plist, so how could that fix it!?
Odd. But good, as no freezes for a while now.

I'll post if the freezes return

What did I try to reproduce the freezes?
Ok, just added Keep above Other Windows. No Freezes
Just opened PowerPoint with one document, no presentation mode. No Freezes
Started dual screen presentation, no freezes.
 
Clicked into the dummy window. Quit BetterDisplay. Re-opened it whilst PowerPoint was open (thought that might mess with PowerPoint). Did not start PiP. Re-entered dual screen presentation mode. No Freezes.
 
Speculating that it is some of the BetterDisplay config changes that cause it.
Hid the dummy's Title Bar and Window Controls. No Freezes.
Opened DB settings. Disabled Expanding menu items. Show button bar at the top of the menu. Started PiP. No Freezes.

[PuzzledUser]

Oh, starting in verbose logging mode didn't show anything after the initial initialisation, when freezes occurred.

[PuzzledUser]

FYI I started seeing the freezes again in V2.3.9. Not seen it since using V3.0.2 today. Mac OS 14.6.1 (23G93 (I was thinking of doing an App reset again, but noticed the new version)

[PuzzledUser]

I started seeing the freezes again, so I reset the app and reconfigured and now no freezes. Odd. Maybe one day I'll have actionable news; I'm currently running in verbose mode, so will leave that terminal window open in the background...

[PuzzledUser]

Just for context considering @exlee's experience, I've been fine since my last reset 3 weeks ago (running the pre-release version at the moment). Hope that doesn't jinx it for me!

[exlee]

Hi!

Something similar happens to me, too. Not couple second but microfreezes, like 0.5-1s every couple seconds. I've noticed that WindowServer %CPU Usage raises to 120-140% while averaging around 40-50% up to 80%. Tried resetting app through "Reset App Settings", but didn't help.

After shutting down BetterDisplay WindowServer CPU Usage dropped to <10% with peaks of 20-30%. Starting BetterDisplay makes it immediatelly raised CPU usage to 45% and went back to idling at 30%.

I've attached WindowServer sample, maybe it'll be helpful.

WindowServer Sample.txt

[waydabber]

Can you share some details (Mac model, displays, app version etc)? WindowServer idling at 30% is very high.

[exlee]

Sure.

This is happening on 14" Macbook Pro with M2 Max with MPG321UR-QD display with 120hz refresh rate and display downscaled to 3008x1692. As for BetterDisplay - I'm using 3.1.2 build 34662 (with Pro license, if it makes any difference).

I don't think I've experienced any issues before Sequoia, however I also started noticing it along with JetBrains IDE usage (and initially put blame there). Another bit I've noticed is that everything seemed fine for some time after restart for the latest update, which makes me believe that detoriation happen gradually but persists over application restart cycle.

[waydabber]

@exlee - can start up the app using this Terminal command (note: quit the app beforehand!) and see whether there is any ongoing log output activity that coincides with the micro-freezes?

/Applications/BetterDisplay.app/Contents/MacOS/BetterDisplay -v

[exlee]

Quick update - I've been running it for half a day, and there wasn't anything especially noisy. I hadn't had any slowdowns so far neither. The only weird thing is this:

[2024-11-19 11:21:09.080] Display with displayID 1 is not in mirror set, is online and active - considered connected 
[2024-11-19 11:21:09.081] Display with displayID 2 is not online - considered disconnected 
[2024-11-19 11:21:09.081] Display with displayID 3 is not online - considered disconnected 
[2024-11-19 11:21:09.081] Display with displayID 4 is not online - considered disconnected 
[2024-11-19 11:21:09.081] Display with displayID 5 is not online - considered disconnected 

I wouldn't be expecting checks for 5 displays, as I have been running 2.