def handle_chld(self, sig, frame):
        """
        SIGCHLD handling
        :param sig:
        :param frame:
        :return:
        """
        try:
            while True:
                wpid, status = waitpid(-1, WNOHANG)
                if not wpid:
                    break
                    # self.stdout.write('%d,%d\n' % (wpid, status))
        except:
            pass