830765 - Multi-second hang during CollectNewLoadedModules

Status: RESOLVED FIXED

(Core :: Widget: Win32, defect)

Description

[Vladan Djeric (:vladan)]

I noticed a 5 second main-thread hang with the following stack:

NtWaitForSingleObject (in wntdll.pdb)
RtlpDeCommitFreeBlock (in wntdll.pdb)
LdrQueryModuleInfoLocalLoaderLock (in wntdll.pdb)
RtlQueryProcessModuleInformation (in wntdll.pdb)
RtlQueryProcessDebugInformation (in wntdll.pdb)
ThpCreateRawSnap (in wkernel32.pdb)
CreateToolhelp32Snapshot (in wkernel32.pdb)
CollectNewLoadedModules (in xul.pdb)
nsAppShell::ProcessNextNativeEvent(bool) (in xul.pdb)
nsBaseAppShell::OnProcessNextEvent(nsIThreadInternal *,bool,unsigned int) (in xul.pdb)
nsThread::ProcessNextEvent(bool,bool *) (in xul.pdb)
mozilla::ipc::MessagePump::Run(base::MessagePump::Delegate *) (in xul.pdb)
MessageLoop::RunHandler() (in xul.pdb)
MessageLoop::Run() (in xul.pdb)
nsBaseAppShell::Run() (in xul.pdb)
nsAppShell::Run() (in xul.pdb)
nsAppStartup::Run() (in xul.pdb)
XREMain::XRE_mainRun() (in xul.pdb)
XREMain::XRE_main(int,char * * const,nsXREAppData const *) (in xul.pdb)
XRE_main (in xul.pdb)
do_main (in firefox.pdb)
wmain (in firefox.pdb)
__tmainCRTStartup (in firefox.pdb)
BaseThreadInitThunk (in wkernel32.pdb)
__RtlUserThreadStart (in wntdll.pdb)
_RtlUserThreadStart (in wntdll.pdb)

This stack is also a frequent chrome-hang. Can we make the CreateToolhelp32Snapshot call off the main thread?

Comment 1

[(no longer active)]

Attachment: Remove the unneeded code

Comment 2

[Jonas Sicking (:sicking) No longer reading bugmail consistently]

Comment on attachment 702393 [details] [diff] [review]
Remove the unneeded code

Review of attachment 702393 [details] [diff] [review]:
-----------------------------------------------------------------

Yes! I don't believe we ever had use for this code. Definitely should go.

Comment 3

[(no longer active)]

http://hg.mozilla.org/integration/mozilla-inbound/rev/97e4a7b942cd

Comment 4

[(no longer active)]

https://hg.mozilla.org/mozilla-central/rev/97e4a7b942cd

Comment 5

[(no longer active)]

Comment on attachment 702393 [details] [diff] [review]
Remove the unneeded code

[Approval Request Comment]
Bug caused by (feature/regressing bug #): bug 524944, sort of.  This was debugging code landed there and never taken out.
User impact if declined: This seems to be one of big chrome hang items that Vladan has been seeing.  As this is pretty much risk free, I think it would be nice to take it on branches.
Testing completed (on m-c, etc.): m-c
Risk to taking this patch (and alternatives if risky): this is just removing unused debugging code.  I'll say risk free.
String or UUID changes made by this patch: none.

Comment 6

[Lukas Blakk [:lsblakk] use ?needinfo]

Comment on attachment 702393 [details] [diff] [review]
Remove the unneeded code

Let's go with uplifting this to Aurora but even though it may be low risk, I think it's too late to take this on Beta and we'll just have to wait for it.

Comment 7

[(no longer active)]

https://hg.mozilla.org/releases/mozilla-aurora/rev/88daa2beccb3