[Xquartz-dev] Autolaunched X11 doesn't work with fast-user-switching

[Ben Byer]

This is odd -- on my system, starting up X11 using multiple users  
logged in at the same time works just fine.  Then again, the debugging  
printfs I added don't even seem to be running at all, so I really have  
no idea what's happening on my Frankenstein-X11 system -- I'll have to  
try this at work tomorrow.

FWIW, .X0-lock is the lock file that corresponds with /tmp/.X11-unix/ 
X0.  The server-main code is supposed to automatically find the first  
available "normal display" number and use it.  Before, that code was  
apparently too conservative (if it saw that socket there, it assumed  
it was still active, and always picked the next display) -- but this  
meant that if your X server died and you restarted it, you'd end up  
with display :1 instead of :0.

Now, it apparently doesn't correctly detect that the socket is still  
active ... ever ...

On Dec 16, 2007, at 1:45 AM, Jeremy Huddleston wrote:

> I think the problem stems from our using the default lock file: / 
> tmp/.X0-lock ... I don't see why the  original Leopard would've  
> worked for you, so can you please check that out and verify?
>
> I'll try to fix this up as I rework the startup stuff... if you  
> haven't already, would you mind filing a bug for it for me, so I  
> don't forget?
>
> Thanks,
> Jeremy
>
> On Dec 15, 2007, at 20:14, Merle Reinhart wrote:
>
>> The original Leopard X11 did not have this problem.  I don't have a  
>> Leopard with the version just prior to X11-2.1.1 at this point in  
>> time to determine if it was X11-2.1.1 where the problem occurred or  
>> not (I can probably get there by the end of the weekend).
>>
>> Merle
>>
>>
>>
>> On Dec 15, 2007, at 8:38 PM, Merle Reinhart wrote:
>>
>>> I've been doing a bit more testing with X11-2.1.1 and find that  
>>> the autolaunching stuff doesn't work if one user already has the  
>>> Xserver started.  At that point, any other user logging in via  
>>> fast-user switching is not able to then use X11 (attempting to set  
>>> DISPLAY to :1.0 and manually start X11.app winds up in an infinite  
>>> loop with Xquartz still trying to talk to the server at :0.0 which  
>>> is owned by the other user).
>>>
>>> At this point in time, I have not been about to find a workaround  
>>> that would allow more than one user to utilize X11.app at the same  
>>> time.  Could this be because launchd is explicitly hard-coded to  
>>> look at the :0 socket when the socket should increase based upon  
>>> the number of logged in users?
>>>
>>> This is potentially a problem with multi-user systems where X11  
>>> may be needed.
>>>
>>> Merle
>>>
>>>
>>>
>>> _______________________________________________
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>>> Xquartz-dev at lists.macosforge.org
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>>
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Ben Byer
CoreOS / BSD Technology Group, XDarwin maintainer