9

我有一些 python 自动化,它产生了我用 linux命令telnet记录的会话;script每个记录会话都有两个script进程 ID(父进程和子进程)。

我需要解决一个问题,如果 python 自动化脚本死了,script会话永远不会自行关闭;出于某种原因,这比它应该的要困难得多。

到目前为止,我已经实现watchdog.py(见问题的底部),它自己守护进程,并在循环中轮询 python 自动化脚本的 PID。当它看到 python 自动化 PID 从服务器的进程表中消失时,它会尝试终止script会话。

我的问题是:

  • script会话总是产生两个单独的进程,其中一个script会话是另一个script会话的父级。
  • watchdog.py script如果我script从自动化脚本启动会话,则不会终止子会话(请参阅下面的自动化示例

自动化示例 ( reproduce_bug.py)

import pexpect as px
from subprocess import Popen
import code
import time
import sys
import os

def read_pid_and_telnet(_child, addr):
    time.sleep(0.1) # Give the OS time to write the PIDFILE
    # Read the PID in the PIDFILE
    fh = open('PIDFILE', 'r')
    pid = int(''.join(fh.readlines()))
    fh.close()
    time.sleep(0.1)
    # Clean up the PIDFILE
    os.remove('PIDFILE')
    _child.expect(['#', '\$'], timeout=3)
    _child.sendline('telnet %s' % addr)
    return str(pid)

pidlist = list()
child1 = px.spawn("""bash -c 'echo $$ > PIDFILE """
    """&& exec /usr/bin/script -f LOGFILE1.txt'""")
pidlist.append(read_pid_and_telnet(child1, '10.1.1.1'))

child2 = px.spawn("""bash -c 'echo $$ > PIDFILE """
    """&& exec /usr/bin/script -f LOGFILE2.txt'""")
pidlist.append(read_pid_and_telnet(child2, '10.1.1.2'))

cmd = "python watchdog.py -o %s -k %s" % (os.getpid(), ','.join(pidlist))
Popen(cmd.split(' '))
print "I started the watchdog with:\n   %s" % cmd

time.sleep(0.5)
raise RuntimeError, "Simulated script crash.  Note that script child sessions are hung"

现在,当我运行上面的自动化时会发生什么......请注意,PID 30017 产生 30018 和 PID 30020 产生 30021。所有上述 PID 都是script会话。

[mpenning@Hotcoffee Network]$ python reproduce_bug.py 
I started the watchdog with:
   python watchdog.py -o 30016 -k 30017,30020
Traceback (most recent call last):
  File "reproduce_bug.py", line 35, in <module>
    raise RuntimeError, "Simulated script crash.  Note that script child sessions are hung"
RuntimeError: Simulated script crash.  Note that script child sessions are hung
[mpenning@Hotcoffee Network]$

在我运行上面的自动化之后,所有子script会话仍在运行。

[mpenning@Hotcoffee Models]$ ps auxw | grep script
mpenning 30018  0.0  0.0  15832   508 ?        S    12:08   0:00 /usr/bin/script -f LOGFILE1.txt
mpenning 30021  0.0  0.0  15832   516 ?        S    12:08   0:00 /usr/bin/script -f LOGFILE2.txt
mpenning 30050  0.0  0.0   7548   880 pts/8    S+   12:08   0:00 grep script
[mpenning@Hotcoffee Models]$

我在 Debian Squeeze linux 系统 (uname -a: Linux Hotcoffee 2.6.32-5-amd64 #1 SMP Mon Jan 16 16:22:28 UTC 2012 x86_64 GNU/Linux) 上运行 Python 2.6.6 下的自动化。

问题:

守护进程似乎无法在产卵过程崩溃中幸存下来。如果自动化死机(如上例所示),我如何修复 watchdog.py 以关闭所有脚本会话?

说明问题的watchdog.py日志(遗憾的是,PID 与原始问题不一致)...

[mpenning@Hotcoffee ~]$ cat watchdog.log 
2012-02-22,15:17:20.356313 Start watchdog.watch_process
2012-02-22,15:17:20.356541     observe pid = 31339
2012-02-22,15:17:20.356643     kill pids = 31352,31356
2012-02-22,15:17:20.356730     seconds = 2
[mpenning@Hotcoffee ~]$

解析度

问题本质上是一个竞争条件。当我试图杀死“父”script进程时,它们已经死于自动化事件......

为了解决这个问题……首先,看门狗守护程序需要在轮询观察到的 PID 之前识别出要杀死的孩子的整个列表(我的原始脚本试图在观察到的 PID 崩溃后识别孩子)。接下来,我必须修改我的看门狗守护程序,以允许某些script进程可能因观察到的 PID 而死。


watchdog.py:

#!/usr/bin/python
"""
Implement a cross-platform watchdog daemon, which observes a PID and kills 
other PIDs if the observed PID dies.

Example:
--------

watchdog.py -o 29322 -k 29345,29346,29348 -s 2

The command checks PID 29322 every 2 seconds and kills PIDs 29345, 29346, 29348 
and their children, if PID 29322 dies.

Requires:
----------

 * https://github.com/giampaolo/psutil
 * http://pypi.python.org/pypi/python-daemon
"""
from optparse import OptionParser
import datetime as dt
import signal
import daemon
import logging
import psutil
import time
import sys
import os

class MyFormatter(logging.Formatter):
    converter=dt.datetime.fromtimestamp
    def formatTime(self, record, datefmt=None):
        ct = self.converter(record.created)
        if datefmt:
            s = ct.strftime(datefmt)
        else:
            t = ct.strftime("%Y-%m-%d %H:%M:%S")
            s = "%s,%03d" % (t, record.msecs)
        return s

def check_pid(pid):        
    """ Check For the existence of a unix / windows pid."""
    try:
        os.kill(pid, 0)   # Kill 0 raises OSError, if pid isn't there...
    except OSError:
        return False
    else:
        return True

def kill_process(logger, pid):
    try:
        psu_proc = psutil.Process(pid)
    except Exception, e:
        logger.debug('Caught Exception ["%s"] while looking up PID %s' % (e, pid))
        return False

    logger.debug('Sending SIGTERM to %s' % repr(psu_proc))
    psu_proc.send_signal(signal.SIGTERM)
    psu_proc.wait(timeout=None)
    return True

def watch_process(observe, kill, seconds=2):
    """Kill the process IDs listed in 'kill', when 'observe' dies."""
    logger = logging.getLogger(__name__)
    logger.setLevel(logging.DEBUG)
    logfile = logging.FileHandler('%s/watchdog.log' % os.getcwd())
    logger.addHandler(logfile)
    formatter = MyFormatter(fmt='%(asctime)s %(message)s',datefmt='%Y-%m-%d,%H:%M:%S.%f')
    logfile.setFormatter(formatter)


    logger.debug('Start watchdog.watch_process')
    logger.debug('    observe pid = %s' % observe)
    logger.debug('    kill pids = %s' % kill)
    logger.debug('    seconds = %s' % seconds)
    children = list()

    # Get PIDs of all child processes...
    for childpid in kill.split(','):
        children.append(childpid)
        p = psutil.Process(int(childpid))
        for subpsu in p.get_children():
            children.append(str(subpsu.pid))

    # Poll observed PID...
    while check_pid(int(observe)):
        logger.debug('Poll PID: %s is alive.' % observe)
        time.sleep(seconds)
    logger.debug('Poll PID: %s is *dead*, starting kills of %s' % (observe, ', '.join(children)))

    for pid in children:
        # kill all child processes...
        kill_process(logger, int(pid))
    sys.exit(0) # Exit gracefully

def run(observe, kill, seconds):

    with daemon.DaemonContext(detach_process=True, 
        stdout=sys.stdout,
        working_directory=os.getcwd()):
        watch_process(observe=observe, kill=kill, seconds=seconds)

if __name__=='__main__':
    parser = OptionParser()
    parser.add_option("-o", "--observe", dest="observe", type="int",
                      help="PID to be observed", metavar="INT")
    parser.add_option("-k", "--kill", dest="kill",
                      help="Comma separated list of PIDs to be killed", 
                      metavar="TEXT")
    parser.add_option("-s", "--seconds", dest="seconds", default=2, type="int",
                      help="Seconds to wait between observations (default = 2)", 
                      metavar="INT")
    (options, args) = parser.parse_args()
    run(options.observe, options.kill, options.seconds)
4

4 回答 4

2

您的问题是该脚本在生成后未与自动化脚本分离,因此它作为孩子工作,并且当父母去世时它仍然无法管理。

要处理 python 脚本退出,您可以使用atexit模块。要监视子进程退出,您可以使用os.wait或处理 SIGCHLD 信号

于 2012-02-22T21:29:38.983 回答
1

您可以尝试杀死包含以下内容的完整进程:父进程script、子进程script、由进程bash生成的进程script,甚至可能是telnet进程。

kill(2)手册说:

如果 pid 小于 -1,则将 sig 发送到ID 为 -pid的进程组中的每个进程。

所以相当于kill -TERM -$PID将完成这项工作。

哦,您需要的 pid 是 parent 的script


编辑

如果我在 watchdog.py 中调整以下两个函数,进程组杀戮似乎对我有用:

def kill_process_group(log, pid):
    log.debug('killing %s' % -pid)
    os.kill(-pid, 15)

    return True

def watch_process(observe, kill, seconds=2):
    """Kill the process IDs listed in 'kill', when 'observe' dies."""
    logger = logging.getLogger(__name__)
    logger.setLevel(logging.DEBUG)
    logfile = logging.FileHandler('%s/watchdog.log' % os.getcwd())
    logger.addHandler(logfile)
    formatter = MyFormatter(fmt='%(asctime)s %(message)s',datefmt='%Y-%m-%d,%H:%M:%S.%f')
    logfile.setFormatter(formatter)

    logger.debug('Start watchdog.watch_process')
    logger.debug('    observe pid = %s' % observe)
    logger.debug('    kill pids = %s' % kill)
    logger.debug('    seconds = %s' % seconds)

    while check_pid(int(observe)):
        logger.debug('PID: %s is alive.' % observe)
        time.sleep(seconds)
    logger.debug('PID: %s is *dead*, starting kills' % observe)

    for pid in kill.split(','):
        # Kill the children...
        kill_process_group(logger, int(pid))
    sys.exit(0) # Exit gracefully
于 2012-02-22T21:24:16.943 回答
0

也许你可以使用 os.system() 并在你的看门狗中执行 killall 来杀死 /usr/bin/script 的所有实例

于 2012-02-22T18:33:38.010 回答
0

经过检查,似乎psu_proc.kill()实际上send_signal())应该在失败时引发OSError,但以防万一 - 您是否尝试在设置标志之前检查终止?如:

if not psu_proc.is_running():
  finished = True
于 2012-02-22T19:02:00.840 回答