Re: gtk-based sip client "locking up"

[Paul Pogonyshev <pogonyshev gmx net>]

Frank W. Miller wrote:
> I'm writing a SIP client for Linux.  It has a command line interface 
> currently but I've recently begun writing a GNOME GUI front-end.  I 
> started with Glade and had reasonable success, i.e. I got it to where is 
> was making outbound calls with decent UI interactions.  I then noticed a 
> problem.  About half the time, when I started to make a call, i.e. when 
> I was sending the first few messages of the SIP dialog, the GUI would 
> "lock up" on me.  What this means is that I have a couple of notebook 
> tabs and some entry fields on each tab.  There are also a couple of 
> buttons.  Its pretty simple.  By lock up, I mean that at some point the 
> GUI just stops updating the various widgets.  If I hit the tabs, it 
> seems like its trying to switch between them but I just get white 
> rectangles and no labels.  The program does not seem to recover from this.
>
> I puzzled over this for a week or so and then thought it might be some 
> strange thing with Glade so I went and rewrote the whole thing from 
> scratch by hand.  I have the same behaviour from this version of the 
> GUI.  I've come the conclusion that there must be something I am either 
> doing or not doing that causes this and I'm hoping someone can help me 
> with a pointer in the right direction!

I'd try two things:

1) Valgrind.  It's not easy to find memory leaks in GTK+ code because GTK+
   itself and especially X (it seems) both leak like mad, but reads of
   uninitialized memory, writes to unallocated memory and such are easily
   spottable with Valgrind.

2) Start your program under GDB, wait for it to lock up, hit Ctrl-C in the
   terminal and study the backtrace.  Thus you can find in which function
   it locks up.  Tracking _why_ it freezes can be more difficult, though ;)

Paul