983829 - Has bug 840277 (preallocated processes dying before use) returned in Nuwa mode?

Status: RESOLVED WONTFIX

(Core :: DOM: Content Processes, defect)

Description

[Jed Davis [:jld] ⟨⏰|UTC-7⟩ ⟦he/him⟧]

ContentParent::SetPriorityAndCheckIsAlive checks if the child process is still alive after changing its priority using waitpid.  If the child process was created via Nuwa, this will fail with ECHILD because it's not a direct child of the main process, so we assume the child is always alive in that case.

This seems as if it could bring back bug 840277, where launching an app could fail if the preallocated process was killed before its priority was raised (but after we decide to use it), and the various bugs that were caused by that.


If that is the case, and we need to fix that: the Nuwa process could report the status of its children to the parent via IPC (or something else, if IPC can't be used), but this doesn't work if the Nuwa process is killed while it still has living children.  But if we only care about the preallocated process, then we could just kill it if that happens (see also bug 977905).  There's also kill(pid, 0), but that could give a false positive if the pid is reused.  (Also, it won't work on regular children, which will still exist as zombies at that point.)

Comment 1

[Jan Beich]

Nuwa is gone after bug 1284674.