Stupid questions about debugging kde apps

[Ralf Habacker]

Thiago Macieira schrieb:
> Marc Espie wrote:
>   
>> In my opinion, there's a lot of stuff missing in DEBUG (the one in
>> kdelibs).
>>
>> - is there a magical cmake settings to compile applications with
>> debugging info, BUT without any of the extra messages ? I need this
>> because of a few heisenbugs, I've got at least two or three instances
>> of crashes that go away when I compile with full debug info, so I
>> suspect that some of the debug code does have side-effects.
>>     
>
> Two possible reasons for that:
> 1) code being called from inside kDebug(), which means it won't get called 
> from a release-mode build
>
> or 2) a real heisenbug that goes away in a debug-mode build simply because 
> of different compiler flags or memory layout.
>
> To turn off debugging completely, set the macro that is listed in 
> kdebug.h.
>
>   
>> - should document stuff like -nofork along with -nocrashhandler... any
>> apps that don't react to -nofork ?  Writing out the basic kde app model
>> in there would make sense (is it still fork() from kdeinit ?)
>>     
>
> They are documented:
>   --nocrashhandler          Disable crash handler, to get core dumps
>   --nofork                  Do not run in the background.
>
> The --nofork option only applies to applications deriving from 
> KUniqueApplication.
>
> KDE applications are normal applications. A KUniqueApplication will 
> fork(): the parent process exits, the child continues. kdeinit is 
> just .the master app launcher: fork + exec.
>
>   
>> - what's the protocol about kioslave debugging ? Especially when you're
>> not on linux, you do not get symbol backtrace. This is really poorly
>> documented... I found out about DBUS_BLOCK_ON_ABORT, which is good.
>> Now I'm stuck (don't laugh) because I actually do not know which app it
>> is running, so I don't know which symbol-set to load...
>>     
>
> KDE_SLAVE_DEBUG_WAIT=protocol kdeinit4
>
> Works by calling raise(SIGSTOP) in the beginning of the ioslave, before 
> control is passed to the slave code. I don't care about platforms where 
> raise() doesn't work.
>   
on win32 the environment variable KDE_SLAVE_DEBUG_WAIT is also supported
set KDE_SLAVE_DEBUG_WAIT=procotol
kdeinit4

for msvc builds kioslave calls a just in time debugger (for example 
windbg from the Micrososft Debugging Tools  installed with windbg -i or 
the build in just in time debugger of MSVC VC++ 2005). For gcc builds 
kioslave starts gdb, which attaches to the running kioslave process. In 
both cases kioslave is stopped before control is passed to the slave code. 

See 
http://websvn.kde.org/trunk/KDE/kdelibs/kinit/kioslave.cpp?view=markup 
for the concret implementation.

Ralf