How do I do that sir?
During the 'hang' the gdb is not in control anymore. I mean during the 'hang' there is no

(gdb) 

prompt to give to backtrace command.
I can type it but the gdb will not respont because it has give control to to application (even during the 'hang')
Wait....

I have now given  a ctrl-z during the hang.
now I can give the backtrace command in gdb
I hope it now give the right backtrace log. After ctrl-z the output of gdb is:
 
Program received signal SIGTSTP, Stopped (user).
[Switching to Thread -1223780656 (LWP 7513)]
0xffffe410 in __kernel_vsyscall ()
(gdb)

now I type the commands to create the log:

(gdb) backtrace

output
#0  0xffffe410 in __kernel_vsyscall ()
#1  0xb75b8033 in read () from /lib/tls/i686/cmov/libc.so.6
#2  0xb75594f8 in _IO_file_read () from /lib/tls/i686/cmov/libc.so.6
#3  0xb755a8c0 in _IO_file_underflow () from /lib/tls/i686/cmov/libc.so.6
#4  0xb755afbb in _IO_default_uflow () from /lib/tls/i686/cmov/libc.so.6
#5  0xb755c31d in __uflow () from /lib/tls/i686/cmov/libc.so.6
#6  0xb75500b6 in _IO_getline_info () from /lib/tls/i686/cmov/libc.so.6
#7  0xb7550001 in _IO_getline () from /lib/tls/i686/cmov/libc.so.6
#8  0xb754efaa in fgets () from /lib/tls/i686/cmov/libc.so.6
#9  0xb4f814ce in ?? () from /lib/libnss_mdns4.so.2
#10 0xbfc63554 in ?? ()
#11 0x00000100 in ?? ()
#12 0x0846b900 in ?? ()
#13 0x00000100 in ?? ()
#14 0xb78300e4 in g_type_check_instance_is_a () from /usr/lib/libgobject-2.0.so.0
#15 0xb4f80a51 in _nss_mdns4_gethostbyaddr_r () from /lib/libnss_mdns4.so.2
#16 0xb75dda7f in gethostbyaddr_r () from /lib/tls/i686/cmov/libc.so.6
#17 0xb75dd8a1 in gethostbyaddr () from /lib/tls/i686/cmov/libc.so.6
#18 0x0806071c in ?? ()
#19 0xb778ec36 in g_hash_table_foreach () from /usr/lib/libglib-2.0.so.0
#20 0x08060097 in ?? ()
#21 0x0806088e in ?? ()
#22 0xb779c3c6 in ?? () from /usr/lib/libglib-2.0.so.0
#23 0x081b13a0 in ?? ()
#24 0x082ae4d8 in ?? ()
#25 0xbfc63a68 in ?? ()
#26 0xb7802748 in ?? () from /usr/lib/libglib-2.0.so.0
#27 0xb7642be0 in ?? () from /lib/tls/i686/cmov/libpthread.so.0
#28 0x083f9eb0 in ?? ()
#29 0xbfc63a78 in ?? ()
#30 0xb77b3fd2 in g_slist_prepend () from /usr/lib/libglib-2.0.so.0
#31 0xb779bdf2 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#32 0xb779edcf in ?? () from /usr/lib/libglib-2.0.so.0
#33 0x08096900 in ?? ()
#34 0x00000000 in ?? ()

(gdb) info registers
output:
eax            0xfffffe00       -512
ecx            0xb4f7f000       -1258819584
edx            0x400    1024
ebx            0x12     18
esp            0xbfc6343c       0xbfc6343c
ebp            0xbfc63460       0xbfc63460
esi            0x846b900        138852608
edi            0xb4f7f000       -1258819584
eip            0xffffe410       0xffffe410 <__kernel_vsyscall+16>
eflags         0x246    [ PF ZF IF ]
cs             0x73     115
ss             0x7b     123
ds             0x7b     123
es             0x7b     123
fs             0x0      0
gs             0x33     51

(gdb) thread apply all backtrace
output:
Thread 1 (Thread -1223780656 (LWP 7513)):
#0  0xffffe410 in __kernel_vsyscall ()
#1  0xb75b8033 in read () from /lib/tls/i686/cmov/libc.so.6
#2  0xb75594f8 in _IO_file_read () from /lib/tls/i686/cmov/libc.so.6
#3  0xb755a8c0 in _IO_file_underflow () from /lib/tls/i686/cmov/libc.so.6
#4  0xb755afbb in _IO_default_uflow () from /lib/tls/i686/cmov/libc.so.6
#5  0xb755c31d in __uflow () from /lib/tls/i686/cmov/libc.so.6
#6  0xb75500b6 in _IO_getline_info () from /lib/tls/i686/cmov/libc.so.6
#7  0xb7550001 in _IO_getline () from /lib/tls/i686/cmov/libc.so.6
#8  0xb754efaa in fgets () from /lib/tls/i686/cmov/libc.so.6
#9  0xb4f814ce in ?? () from /lib/libnss_mdns4.so.2
#10 0xbfc63554 in ?? ()
#11 0x00000100 in ?? ()
#12 0x0846b900 in ?? ()
#13 0x00000100 in ?? ()
#14 0xb78300e4 in g_type_check_instance_is_a () from /usr/lib/libgobject-2.0.so.0
#15 0xb4f80a51 in _nss_mdns4_gethostbyaddr_r () from /lib/libnss_mdns4.so.2
#16 0xb75dda7f in gethostbyaddr_r () from /lib/tls/i686/cmov/libc.so.6
#17 0xb75dd8a1 in gethostbyaddr () from /lib/tls/i686/cmov/libc.so.6
#18 0x0806071c in ?? ()
#19 0xb778ec36 in g_hash_table_foreach () from /usr/lib/libglib-2.0.so.0
#20 0x08060097 in ?? ()
#21 0x0806088e in ?? ()
#22 0xb779c3c6 in ?? () from /usr/lib/libglib-2.0.so.0
#23 0x081b13a0 in ?? ()
#24 0x082ae4d8 in ?? ()
#25 0xbfc63a68 in ?? ()
#26 0xb7802748 in ?? () from /usr/lib/libglib-2.0.so.0
#27 0xb7642be0 in ?? () from /lib/tls/i686/cmov/libpthread.so.0
#28 0x083f9eb0 in ?? ()
#29 0xbfc63a78 in ?? ()
#30 0xb77b3fd2 in g_slist_prepend () from /usr/lib/libglib-2.0.so.0
#31 0xb779bdf2 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#32 0xb779edcf in ?? () from /usr/lib/libglib-2.0.so.0
#33 0x08096900 in ?? ()
#34 0x00000000 in ?? ()

(gdb) quit
Output:
The program is running.  Exit anyway? (y or n)

I respond with 'y'
The log file is created
I have included this file.
I hope now you have the right information.

Regards,