1620614 - Crash in [@ IPCError-browser | ShutDownKill | mozilla::dom::XMLHttpRequestMainThread::SendInternal]

Status: RESOLVED WORKSFORME

(Core :: DOM: Core & HTML, defect, P3)

Description

[Andrew McCreight [:mccr8]]

This bug is for crash report bp-9fbefcb1-6e62-4da0-9169-503370200306.

Top 10 frames of crashing thread:

0 ntdll.dll ZwWaitForKeyedEvent 
1 ntdll.dll RtlSleepConditionVariableSRW 
2 kernel32.dll SleepConditionVariableSRW 
3 mozglue.dll mozilla::detail::ConditionVariableImpl::wait mozglue/misc/ConditionVariable_windows.cpp:50
4 xul.dll mozilla::ThreadEventQueue<mozilla::PrioritizedEventQueue>::GetEvent xpcom/threads/ThreadEventQueue.cpp:208
5 xul.dll nsThread::ProcessNextEvent xpcom/threads/nsThread.cpp:1140
6 xul.dll NS_ProcessNextEvent xpcom/threads/nsThreadUtils.cpp:481
7 xul.dll mozilla::dom::XMLHttpRequestMainThread::SendInternal dom/xhr/XMLHttpRequestMainThread.cpp:2956
8 xul.dll mozilla::dom::XMLHttpRequestMainThread::Send dom/xhr/XMLHttpRequestMainThread.cpp
9 xul.dll mozilla::dom::XMLHttpRequest_Binding::send dom/bindings/XMLHttpRequestBinding.cpp:1303

It looks like we're spinning the event loop while waiting for a reply to a sync XHR, and this goes on for so long that we're still in the middle of it when we get a shutdown message from the parent, so we don't actually shut down. Is there some way we could cancel the sync XHR when we get the shutdown message?

Comment 1

[Henri Sivonen (:hsivonen) (on leave)]

We should probably check for some kind of "shutting down" flag in:
https://searchfox.org/mozilla-central/rev/557a0e222dd104c5d805ba344c45d6abc27d3db0/dom/xhr/XMLHttpRequestMainThread.cpp#2956

Do we already have a libxul-wide flag that gets set as soon as we have committed to shutting down?

Comment 2

[Andrew McCreight [:mccr8]]

Not that I'm aware of, but that does sound like a good idea. You'd have to listen for content-child-will-shutdown in the child processes, and something else in the parent.

Comment 3

[Andrew McCreight [:mccr8]]

An alternative would be to write something that pokes at ContentChild in the child and gets the shutdown flag there. Maybe there's something equivalent in ContentParent that could be done there.

Comment 4

[Henri Sivonen (:hsivonen) (on leave)]

Thanks. Hopefully we aren't doing sync XHR from the parent, so checking ContentChild::IsShuttingDown() should be enough.

Comment 5

[BugBot [:suhaib / :marco/ :calixte]]

Closing because no crashes reported for 12 weeks.