libX11/XCB problems in Hardy

[Stefan Potyra]

Hi Bryce,

Am Samstag 21 Juni 2008 19:35:10 schrieben Sie:
> On Sat, Jun 21, 2008 at 01:13:22PM +0200, Stefan Potyra wrote:
> > Now this might be a red herring, and not related with this at all, but
> > I've been having troubles with xcb in FAUmachine with hardy as well. It
> > turned out that file descriptors registered in blocking mode caused a
> > hang in xcb (which wasn't a problem in gutsy yet). Relevant file is at
> > [1], and the diff which solved it is [2].
>
> While it's not evident to me either, it would not surprise me if the
> root cause of this was related, since they both deal with blocking
> situations.

yeah, that's why I wrote that it might be a red herring. However one backtrace 
listed in the dbus bug was somehow familiar to me.

>
> Do the FAUmachine troubles occur 100% of the time or intermittently?
> The Xubuntu folks were finding the issue to be intermittent, making us
> think it's a race condition of some sort.

Back then (i.e. when I committed the change) it happened on every start of 
FAUmachine. Haven't tried with any hardy-updates yet though. Will do.

>
> > If you think, that this might somehow be connected, and digging in that
> > direction might bring us closer to the issue, I could try to boild down
> > the relevant code parts to a minimal test case.
>
> That would be great - it'd give us something we could give to upstream
> to test against, and so we can validate new code from them to make sure
> it doesn't have this problem.

Ok, will do so (probably not before Monday though).


P.S.: One thing that iirc struck me back then was that the older xcb actually 
inserted a first event into the queue, which was not done for hardy. However 
thats solely from my memory of lookingh very thinly at xcb more than 7 weeks 
ago, so I it needn't be true at all.

Cheers,
    Stefan.
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