Deadock Xorg runing strace on a client (from within a client terminal)

[Rémi Cardona]

Peter Harris a écrit :
> Adam Jackson wrote:
>> On Thu, 2008-08-28 at 15:50 +0100, Alan Cox wrote:
> <about strace>
>>> If you trace through a server grab you may well end up with the app you
>>> are tracing owning a grab on the server and preventing the other clients
>>> writing. Its an annoying bit of historic X design.
>> That's only a deadlock if the client with the grab is waiting for the
>> tracing client to do something before releasing the grab.  This is
>> almost certainly not the case here.
> 
> Client grabs server.
> xterm blocks writing to server.
> strace blocks writing to xterm.
> Client blocks in strace.
> 
> This can easily deadlock if there is enough strace activity under the
> grab to fill up the various pipe/socket buffers.

I can definitely confirm this behavior. On a busy server, this usually
happens in less than a second or two, making (live) stracing Xorg
impossible with only one machine.

Cheers

-- 
Rémi Cardona
LRI, INRIA
remi.cardona at lri.fr
remi at gentoo.org