Hi Walid,
(cross-posting to devs@lists.arctica-project.org)


On  Mo 06 Feb 2017 12:55:57 CET, Walid MOGHRABI wrote:

> I have been testing current NX-Libs snapshot with the Stable Arctica  
> repo (not the nightly).
> There are many good things with this update but I encounter crashes  
> quite too often to use them for Prod (I know, it is
> discouraged but if at least it would have been stable, I could have  
> tried anyway).

I have worked with high pressure on various issues. Now my reviewers  
need to give a go for merging all the proposed changes.

See https://github.com/ArcticaProject/nx-libs/pulls

> Can somebody simply tells me how I can debug things and report bugs  
> and to who and how ?

One thing you can do is run nxagent sessions in valgrind and see what  
that outputs when sessions crash (or throw errors otherwise). For this  
you need to modify /usr/bin/nxagent as given below:

```
#!/bin/bash

# Copyright (C) 2012 Mike Gabriel <mike.gabriel@das-netzwerkteam.de>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see http://www.gnu.org/licenses/.

NX_LIBS="/usr/lib/x86_64-linux-gnu"/nx

# make sure nxagent starts properly with pam_tmpdir.so being in use
NX_TEMP=${NX_TEMP:-/tmp}
export NX_TEMP
export LD_LIBRARY_PATH="/usr/lib/x86_64-linux-gnu"/nx-X11/

WITH_VALGRIND="valgrind --log-file=$HOME/valgrind.log"

exec $WITH_VALGRIND $NX_LIBS/bin/${NXAPP:-"nxagent"} "$@"

```

Another option is to create core dumps. We are working on a patch that  
produces them automatically (under debug circumstances). These core  
dumps can then be post-mortem be analyzed with gdb.

If your nxagent session does not die immediately, but under certain  
conditions (something that you click or do in your session), you can  
attach a gdb to the running nxagent (or x2goagent process). There is a  
good howto for X11 debugging that also applies to debugging  
nxagent/x2goagent. Take a look at this howto for this:
https://www.x.org/wiki/Development/Documentation/ServerDebugging/


> Must I send them to the X2Go tracker or is there another one ?

Please use https://github.com/ArcticaProject/nx-libs/issues

Thanks!

> Which information should I give and are there some settings I should  
> enable to get more traces ?

If valgrind throws an error, please dump the important parts of the  
valgrind output into a bug report. If you see more than one bug, try  
to dissect the output and file separate bug reports.

When observing a crash in gdb, we need the backtrace and here and  
there, it might help to "print" some variables, to see what their  
values are. Refer to gdb howtos on this, please.

> By now, I encountered 2 problems, one that is minor (keyboard is  
> reverting to QWERTY layout instead of AZERTY - French layout when  
> suspending/resuming a session between 2 TCEs) and one that is

We need a very exact description on how to reproduce that keyboard  
issue. Please file an explanatory issue on Github first, then we try  
to track that down. Be prepared to sponsor me or Uli or Ionic with a  
matching keyboard. ;-) Give as much _relevant_ information as  
possible, esp. regarding your system's locale and keyboard  
configuration (server and client side).

> critical, aka X session that crashes but randomly (but at least , I  
> get a core dump).

Ok, try to get a backtrace from that core dump. It is easier to do  
that on the machine where you have the exact matching executables (and  
libraries) at hand (+ the debug symbols). You can also build nxagent  
from source and then debug that binary self-built version.

> So, I'm not bug reporting here, I just want some clarifications on  
> how to report correctly bugs concerning Arctica NX-Libs and to who  
> and where.

The Arctica NX-Libs will also be NX-Libs that arrive in X2Go at some  
point. At the moment, consider Arctica as NX-Libs upstream for X2Go.  
X2Go legacy-maintains the 3.5.0.x branch of NX-Libs while we (and in  
personalia we partially overlap) work on the bleeding edge stuff.

Hope you have enough info for now, please get back to us.

Greets,
Mike
-- 

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