We sometimes attempt to use a terminated prewarmed WebContent process, in particular upon resuming the UIProcess from suspension and when the prewarmed process has been jetsammed while we were suspended. In this case, upon resuming, it may take a while to get the notification that the mach connection has been closed and we'll use the prewarmed process. When we finally end up getting the notification, it is too late. We notify the client and it usually shows a crash banner. Ideally, we would not use such process in the first place.
It is also arguable whether it makes sense to keep prewarmed processes around when the UIProcess gets suspended.
Created attachment 378408 [details]
Comment on attachment 378408 [details]
r=me if you update to resolve merge conflict
Created attachment 378424 [details]
Comment on attachment 378424 [details]
Clearing flags on attachment: 378424
Committed r249703: <https://trac.webkit.org/changeset/249703>
All reviewed patches have been landed. Closing bug.