Debugging Multiple Processes/Threads with GDB

Debugging multiple inferiors and programs
Gdb allows you to debug multiple programs at once without exiting the process you're currently running.
Gdb uses an inferior as a handle for a process. An inferior  is attachable/detachable from a process
    info inferiors    # display list of current inferiors.

     (gdb) info inferiors
       Num  Description       Executable
       2    process 2307      hello
     * 1    process 3401      goodbye

Switch to another inferior:
    inferior infno   # make inferior number infno the current inferior

Loading multiple inferiors:
1)    add-inferior [ -copies n ] [ -exec executable ] # n defaults to 1 and optional exec gives an empty inferior
2)    clone-inferior [ -copies n ] [ infno ]    # n defaults to 1 and infno defaults to current inferior number

Ending the inferiority complex:
remove-inferior infno        # Remove the empty inferior Note: Can't remove an inferior with a running assoc. process.
detach-inferior infno         # detaches from an inferior from assoc. process
kill-inferiror infno             # kills the process attached to the inferior. It can be removed or re-attached to some process.

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Debugging Multi-threaded Programs:
    info threads    # displays thread info - thread number, thread-id,  stack frame summary
    thread threadno     # make threadno as active current thread and shows stack frame summary

Starting and Stopping Multi-thread Programs
2 modes of debugging:
1) All stop mode: aka 3 musketeers mode i.e. "All-for-one, One-for-all"
2) Non-stop mode:
    set target-async on|off    # Switch asynchronous mode.
    show target-async         # Show the current target-async setting.

    interrupt    # suspend execution of the running program (whole process in all-stop, current thread in non-stop modes)
    interrupt -a    # stop the whole program in non-stop mode