Bug 214650

Summary: [iOS] Avoid rebuilding MobileGestalt cache if IOKit is busy
Product: WebKit Reporter: Per Arne Vollan <pvollan>
Component: WebKit Misc.Assignee: Per Arne Vollan <pvollan>
Status: NEW ---    
Severity: Normal CC: bfulgham, ggaren, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
Patch ap: review-

Description Per Arne Vollan 2020-07-22 12:52:59 PDT 
If IOKit is busy, any attempt to rebuild the MobileGestalt cache will likely fail after a timeout. To avoid blocking the main thread in the UI process, skip rebuilding the MobileGestalt cache if IOKit is busy.
Comment 1 Per Arne Vollan 2020-07-22 12:53:43 PDT 
rdar://problem/65882633
Comment 2 Per Arne Vollan 2020-07-22 13:03:06 PDT 
Created attachment 404954 [details]
Patch
Comment 3 Geoffrey Garen 2020-07-22 13:24:11 PDT 
Today, if the MG cache is invalid, we get hang reports about it. That's not the best signal, but it's some signal nonetheless.

I can see how this patch would make the hang go away, but the next thing that will happen is a mysterious failure in the WebContent process (most likely a failure to play media). Is that an improvement?

Did we find to what exactly what keeping IOKit busy on the device that triggered this hang?
Comment 4 Alexey Proskuryakov 2020-07-23 17:45:37 PDT 
Comment on attachment 404954 [details]
Patch

r- because of red EWS, but yes, what Geoff said.