Users occasionally experience system unresponsiveness and unexpected black screen restarts during meetings in our app

Question

Created Dec ’24

Replies 2

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Participants 2

We have received user reports indicating that, while using our app for meetings, they occasionally encounter system unresponsiveness, ultimately leading to an unexpected black screen and system restart.

Our app's internal logs show normal operation during these incidents.

To assist in diagnosing the issue, we have collected system logs (WindowServer.ips) from affected users.

We would appreciate your assistance in analyzing these logs to help identify the root cause of the problem.

Thank you for your support and assistance.

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Answer 1

sunjinglin OP

Dec ’24

"deployVersion": 210, "variant": "stackshot", "incident": "9B3073C4-81D9-4A89-8E18-8726E6E863A6", "crashReporterKey": "67A2CB7C-DCF6-7BD4-40B9-2B049A3589A0", "modelCode": "MacBookPro17,1", "cpuType": "00000000", "osVersion": { "train": "macOS 15.2", "build": "24C101", "releaseType": "User" }, "variantVersion": 2, "captureTime": "2024-12-18 13:23:27.8584 +0800", "pid": 598, "bug_type": "409", "procName": "WindowServer", "bundleInfo": { "CFBundleIdentifier": "WindowServer" }, "termination": { "flags": 0, "indicator": "monitoring timed out for service", "code": 1, "namespace": "WATCHDOG", "details": [ "(1 monitored services unresponsive): checkin with service: WindowServer (0 induced crashes) returned not alive with context:", "unresponsive work processor(s): WindowServer main thread", "40 seconds since last successful checkin, 1316 total successful checkins since 13200 seconds ago, has not exited since first loaded" ] }, "bootSessionUUID": "E5D9CFD0-61E9-405D-A930-164F30AFDE00", "uptime": 13000, "thermalPressureLevel": "ThermalPressureLevelNominal (0)", "displayState": "OFF",

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Answer 2

DTS Engineer OP

Apple

Jan ’25

We have received user reports indicating that, while using our app for meetings, they occasionally encounter system unresponsiveness, ultimately leading to an unexpected black screen and system restart.

First off, please file a bug report on this, upload whatever diagnostic data you have, then post the bug back number here. Once the bug has been filed I'll take a look at the data and see what I can determine.

In terms of what's going on here, there is a mechanism in place where certain system critical daemons are required to "check in" with the kernel on regular basis and, if they fail to do so, the kernel basic forces a kernel panic to force a reboot and restore normal functionality.

40 seconds since last successful checkin

This mechanism exists to generate diagnostic data about issues that would otherwise be "invisible" to us. A system where the WindowServer has been unable to communicate with the kernel for 40+ seconds is NOT functional from the users perspective, even if other process are seemingly working fine.

Finally, one point to clarify about the "bug" here. From the systems perspective, the bug here is that the system has hung which should "never" happen, so we should fix that. However, the tricky part here is what "fix" actually means- that fix could mean that we resolve an underlying bug (so everything "just works"), but it might also mean that we identify the triggering circumstance and "solve" the problem but directly breaking your app (for example, but returning an error you're not expecting or by simply terminating your process).

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Kevin Elliott
DTS Engineer, CoreOS/Hardware

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