I am running my Qt app from gdb, and i want to stop when new threads creates.
(when gdb prints message [New Thread address (LPW number)].
I have set breakpoint b __pthread_create_2_1.
That allows me to catch most of new threads prints. but i still got few new threads that are not catched.
What else can i do to catch their creation?
Probably what you want is
catch syscall clone (see here https://sourceware.org/gdb/onlinedocs/gdb/Set-Catchpoints.html)
Also by default gdb let other threads continue their execution if a breakpoint or catchpoint event occurs. So maybe you want to take a look at the All-Stop mode (https://sourceware.org/gdb/onlinedocs/gdb/Thread-Stops.html)