Thread: signal not received

  1. #1
    Its me!

    Question signal not received


    does anyone know any problems with signals being sent successfull but not being received?

    I am using signal (SIGUSR1, handler); to trap signals.

    I am raising a signal using kill(SIGINT, pid);

    The kill command returns a 0 meaning it is successful, but the handler never receives it.

    This happens when a lot of signals are sent to a lot of processes in a short time frame.

    Thanks for help....

  2. #2
    Banned Troll_King's Avatar
    Join Date
    Oct 2001
    Either try the Linux board if you are using Linux, or else for Microsoft this involves Win32 and is designated for the Windows Programming Board.

  3. #3
    Its me
    I am using solaris 5.8 and using the gnu C compiler....

  4. #4
    and the hat of int overfl Salem's Avatar
    Join Date
    Aug 2001
    The edge of the known universe
    > This happens when a lot of signals are sent to a lot of processes in a short time frame.
    I'd say this is the problem. Signals are exceptions, not a means of communication between processes. In particular, each process doesn't have an infinitely deep queue of pending signals.

    Some signal handlers reset to default behaviour when they are triggered (default being to ignore).

    You need to read up in depth on how signals are handled.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.

  5. #5
    Registered User Engineer's Avatar
    Join Date
    Oct 2001
    It happens because you are trapping SIGUSR1 and everything in your signal handler will occur only when SIGUSR1 is raised. But you are in fact raising SIGINT ( which is a completely different signal). Try to do:

    signal( A, handler); and kill( A, pid );

    what you are doing now is:

    signal( A, handler); and kill( B, pid );

    Hope I explained it well enough.
    1 rule of the Samurai Code: if you have nothing to say, don't say anything at all!

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