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.pyscript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)