[winswitch] Xpra crash (Gdk error)

[Antoine Martin]

On 14/02/17 06:45, Lukas Haase via shifter-users wrote:
> Hi,
> 
> Once in a while xpra crashes with a message like the following:
> 
> Gdk-ERROR **: The program 'Xpra' received an X Window System error.
> This probably reflects a bug in the program.
> The error was 'BadWindow (invalid Window parameter)'.
>   (Details: serial 30573157 error_code 3 request_code 3 minor_code 0)
>   (Note to programmers: normally, X errors are reported asynchronously;
>    that is, you will receive the error a while after causing it.
>    To debug your program, run it with the --sync command line
>    option to change this behavior. You can then get a meaningful
>    backtrace from your debugger if you break on the gdk_x_error() function.)
> aborting...
> Abort (core dumped)
This GDK error can occur when:
1) xpra fails to synchronize / flush the connection to the X11 server
after making a native X11 call
2) xpra calls X11 functions from the wrong thread
Both are bugs.

> The X server (Xorg-nosuid /usr/bin/Xorg -noreset -nolisten tcp +extension GLX +extension RANDR +extension RENDER -logfile /home/lukas/.xpra/Xorg-10.log -config /etc/xpra/xorg.conf :2000) as well as the client continue running in the background.
> 
> I think it is hopeless to debug this and hence do not want to file a bug report because this occurs after working for many days. So debugging/getting this reproducible is hopeless and even if I would enable logging, the log file would probably be GB size.
The log file would still be useful to see: the last few entries in it
would tell us what part of the code was potentially doing this illegal
access.

> I would rather like to understand what's going on and maybe prevent doing actions that could result in this state.
Looks like a bug needs fixing in xpra..

> Any idea what could cause a situation like this?
> 
> Since the error is "BadWindow" I also want to mention that the xpra continuously generates output like this:
> 
> 2017-02-13 12:36:36,599 failed to manage client <gtk.gdk.Window object at 0x7fa154183460 (GdkWindow at 0x472c7e0)>: XError: BadWindow
> Traceback (most recent call last):
>   File "/usr/lib64/python2.6/site-packages/xpra/x11/gtk2/wm.py", line 346, in _manage_client
>     self.do_manage_client(gdkwindow)
>   File "/usr/lib64/python2.6/site-packages/xpra/gtk_common/error.py", line 168, in __exit__
>     trap._exit(True)
>   File "/usr/lib64/python2.6/site-packages/xpra/gtk_common/error.py", line 100, in _exit
>     raise XError(get_X_error(error))
> XError: XError: BadWindow
> 2017-02-13 12:36:36,609 failed to manage client <gtk.gdk.Window object at 0x2a58640 (GdkWindow at 0x385bc60)>: XError: BadWindow
> Traceback (most recent call last):
>   File "/usr/lib64/python2.6/site-packages/xpra/x11/gtk2/wm.py", line 346, in _manage_client
>     self.do_manage_client(gdkwindow)
>   File "/usr/lib64/python2.6/site-packages/xpra/gtk_common/error.py", line 168, in __exit__
>     trap._exit(True)
>   File "/usr/lib64/python2.6/site-packages/xpra/gtk_common/error.py", line 100, in _exit
>     raise XError(get_X_error(error))
> XError: XError: BadWindow
It should be harmless and just means that the window disappeared before
we could manage it.
We probably shouldn't be logging an error here.

> as well as:
> 
> 2017-02-13 15:13:01,663 client 64: unknown string message: 0xc22fL / 49371 / 0
This is a message specific to MS Windows clients, we just log the ones
we are not expecting to see just in case they provide us a clue for bugs
/ unusual behaviour.

> but xpra does not crash - usually for days.
> However, after a couple of days xpra server will eventually crash with the Gdk error above.
> 
> It also seems that I can resume the X server/X client with "xpra upgrade" (which mitigates the problem a bit).
Ideally, we could fix that bug and avoid the need for "xpra upgrade".

Cheers
Antoine
> 
> 
> Thanks,
> Lukas
> 
> 
> 
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