Having similar restarts, with a bunch of panic-full logs mentioning messages similar to "panic(cpu 0 caller 0xfffffff04499471c): userspace watchdog timeout: no successful checkins from SpringBoard (2 induced crashes) in 180 seconds". The hangs seem to happen random times in the day, though just before 7 pm seems to be fairly common. Looking at the logs I noticed the following:
"turnstileInfo": [
"thread 452495: blocked on 452623, hops: 1, priority: 47",
"thread 452560: turnstile has unknown inheritor",
"thread 452612: turnstile has unknown inheritor",
"thread 452623: turnstile blocked on task pid 1, hops: 3, priority: 47 (com.apple.iconservices (service throttled by launchd))",
"thread 452627: blocked on 452495, hops: 2, priority: 20 (com.apple.springboard.backgroundappservices)"
],
"pageIns": 38,
"systemTimeTask": 0.46156837499999998,
"rawFlags": "0x4409C401",
"portlabels": {
"3": "com.apple.iconservices (service throttled by launchd)",
"5": "com.apple.springboard.backgroundappservices"
},
"timesDidThrottle": 0,
"csTrustLevel": 7,
"waitInfo": [
"thread 452495: unfair lock 0x2026b8cc0 owned by thread 452623",
"thread 452560: spinlock 0x16f3a27a0",
"thread 452612: spinlock 0x16fa32ab0",
"thread 452621: pthread condvar 0x27f9edc58",
"thread 452623: mach_msg receive on port 0x336df9da4b210d75 name 0x4d0b",
"thread 452627: mach_msg receive on port 0x336df9da4a665e35 name 0xe40f",
"thread 452629: mach_msg receive on port set 0x336df9da4df507d5",
"thread 452631: mach_msg receive on port set 0x336df9da4df50805"
],
"procname": "SpringBoard",
Thread 452623 seems to be com.SpringBoardHome.SBHIconImageCache.work appears to be what is hanging springboard, and it seems to be waiting on task 1 / com.apple.iconservices.iconservicesagent.
Looking at task 1 I see:
"name": "user\/501\/com.apple.iconservices.iconservicesagent throttled aft",
And it seems to be waiting on:
"thread 449772: semaphore port 0x336df9da4af8e855 owned by pid 1"
I then checked my logs again and noticed a huge number of iconservicesagent crash logs about including ones around 3 minutes before each of the panic full logs, but many many more, looking at those logs they appear to be sigabrt. Looking further there seems to be a message about Address size fault. One other thing I noticed is that the some of the icons in control center on my phone were blank, until I removed and readded the controls. I can normally tell when its starting to happen as it appears to get laggy when drawing buttons, responding to typing in places where it would show some sort of icon, such as maps, settings, app directory page, search, etc.