'Launch a process and monitor it asynchronously.
:param block: Block until the process has started.
:raises utils.WaitTimeout if blocking is True and the process
did not start in time.'

def start(self, block=False):

    LOG.debug('Launching    async    process    [%s].', self.cmd)
    if self._is_running:
        raise AsyncProcessException(_('Process    is    already    started'))
    else:
        self._spawn()
    if block:
        common_utils.wait_until_true(self.is_active)
