ngamsDaemon.py 文件源码

def kill_and_wait(pid, pidfile):

    # The NGAS server should nicely shut down itself after receiving this signal
    os.kill(pid, signal.SIGTERM)

    # We previously checked that the pidfile was gone, but this is not enough
    # In some cases the main thread finished correctly, but there are other
    # threads (e.g., HTTP servicing threads) that are still running,
    # and thus the PID file disappears but the process is still ongoing
    tries = 0
    max_tries = 20
    sleep_period = 1
    start = time.time()
    while tries < max_tries:

        # SIGCONT can be sent many times without fear of side effects
        # If we get ESRCH then the process has finished
        try:
            os.kill(pid, signal.SIGCONT)
        except OSError as e:
            if e.errno == errno.ESRCH:
                # Bingo! the process is gone
                break

        tries += 1
        time.sleep(sleep_period)
        sys.stdout.write('.')
        sys.stdout.flush()

    sys.stdout.write('\n')
    sys.stdout.flush()
    end = time.time()

    ret = 0x00

    # We waited a lot but the process is still there, kill it with 9
    if tries == max_tries:
        err("Process didn't die after %.2f [s], killing it with -9" % (end-start))
        os.kill(pid, signal.SIGKILL)
        ret += 0x01

    # The process should have removed its own pidfile...
    if os.path.exists(pidfile):
        err("Removing PID file manually, the daemon process didn't remove it by itself")
        os.unlink(pidfile)
        ret += 0x02

    return ret