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