python庫介紹-python-daemon: 實現python後臺程式的工具

Python · 發表 2018-09-17 23:20:59

摘要：簡介 python-daemon實現Unix守護程序。參考：PEP 3143 該庫實現了PEP 3143“標準守護程序庫”的良好行為守護程序規範。 DaemonContext例項儲存程式的行為和配置的程序環境。快速入門 i...

簡介

python-daemon實現Unix守護程序。參考：PEP 3143

該庫實現了PEP 3143“標準守護程序庫”的良好行為守護程序規範。

DaemonContext例項儲存程式的行為和配置的程序環境。

快速入門

import time

with daemon.DaemonContext():
f = open("/tmp/test.log",'w')
while True:
f.write('''
Library to implement a well-behaved Unix daemon process.

This library implements the well-behaved daemon specification of PEP 3143, “Standard daemon process library”.

A well-behaved Unix daemon process is tricky to get right, but the required steps are much the same for every daemon program. A DaemonContext instance holds the behaviour and configured process environment for the program; use the instance as a context manager to enter a daemon state.
''')
f.write("{0}\n".format(time.ctime(time.time())))
time.sleep(1)

執行：

$ python3 daemon1.py 

$ tail -f /tmp/test.log 
This library implements the well-behaved daemon specification of PEP 3143, “Standard daemon process library”.

A well-behaved Unix daemon process is tricky to get right, but the required steps are much the same for every daemon program. A DaemonContext instance holds the behaviour and configured process environment for the program; use the instance as a context manager to enter a daemon state.
Thu Feb8 14:21:43 2018

$ ps afx | grep -i daemon1
 8646 pts/2S+0:00|\_ grep --color=auto -i daemon1
 8640 ?S0:00\_ python3 daemon1.py
$ kill -9 8640

要想停止上述程序，可以通過ps查詢到程序號，然後kill。

注意上述程式碼在python2沒有任何問題，不過在python需要修改庫檔案runner.py開啟檔案的方式。

# vi /usr/local/lib/python3.5/dist-packages/daemon/runner.py 
# 118 -120
self.daemon_context = DaemonContext()
self.daemon_context.stdin = open(app.stdin_path, 'wb+',buffering=0)
self.daemon_context.stdout = open(app.stdout_path,'wb+',buffering=0)
self.daemon_context.stderr = open(
app.stderr_path, 'wb+', buffering=0)

更實用的例子

import time
import logging
import logging.handlers
from daemon import runner

class App():

def __init__(self):
self.stdin_path = '/dev/null'
self.stdout_path = '/dev/tty'
self.stderr_path = '/dev/tty'
self.pidfile_path ='/tmp/foo.pid'
self.pidfile_timeout = 5

def run(self):

logs = logging.getLogger('MyLogger')
logs.setLevel(logging.DEBUG)
fh = logging.handlers.RotatingFileHandler(
'/tmp/test.log',maxBytes=10000000,backupCount=5)
fh.setLevel(logging.DEBUG)
formatter = logging.Formatter(u'%(asctime)s [%(levelname)s] %(message)s')
fh.setFormatter(formatter)
logs.addHandler(fh)

while True:
for i in range(10):
logs.info("Beginning Scan {0}! \n".format(i))
time.sleep(1)

app = App()
daemon_runner = runner.DaemonRunner(app)
daemon_runner.do_action()

執行：

$ python2 daemon2.py 
usage: daemon2.py start|stop|restart

$ python3 daemon2.pystart
andrew@andrew-MS-7A71:~/code/python-chinese-library/libraries/daemon$ 
andrew@andrew-MS-7A71:~/code/python-chinese-library/libraries/daemon$ Traceback (most recent call last):
File "/usr/local/lib/python3.5/dist-packages/lockfile/pidlockfile.py", line 77, in acquire
write_pid_to_pidfile(self.path)
File "/usr/local/lib/python3.5/dist-packages/lockfile/pidlockfile.py", line 161, in write_pid_to_pidfile
pidfile_fd = os.open(pidfile_path, open_flags, open_mode)
FileExistsError: [Errno 17] File exists: '/tmp/foo.pid'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "daemon2.py", line 39, in <module>
daemon_runner.do_action()
File "/usr/local/lib/python3.5/dist-packages/daemon/runner.py", line 274, in do_action
func(self)
File "/usr/local/lib/python3.5/dist-packages/daemon/runner.py", line 182, in _start
self.daemon_context.open()
File "/usr/local/lib/python3.5/dist-packages/daemon/daemon.py", line 389, in open
self.pidfile.__enter__()
File "/usr/local/lib/python3.5/dist-packages/lockfile/__init__.py", line 197, in __enter__
self.acquire()
File "/usr/local/lib/python3.5/dist-packages/daemon/pidfile.py", line 60, in acquire
super(TimeoutPIDLockFile, self).acquire(timeout, *args, **kwargs)
File "/usr/local/lib/python3.5/dist-packages/lockfile/pidlockfile.py", line 85, in acquire
self.path)
lockfile.LockTimeout: Timeout waiting to acquire lock for /tmp/foo.pid

andrew@andrew-MS-7A71:~/code/python-chinese-library/libraries/daemon$ python3 daemon2.pystop
Terminating on signal 15
andrew@andrew-MS-7A71:~/code/python-chinese-library/libraries/daemon$ python3 daemon2.pystop
Traceback (most recent call last):
File "daemon2.py", line 39, in <module>
daemon_runner.do_action()
File "/usr/local/lib/python3.5/dist-packages/daemon/runner.py", line 274, in do_action
func(self)
File "/usr/local/lib/python3.5/dist-packages/daemon/runner.py", line 224, in _stop
raise error
daemon.runner.DaemonRunnerStopFailureError: PID file '/tmp/foo.pid' not locked

注意上面的錯誤是重複啟動或者停止時程序並不存在導致的。

參考資料

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daemonize demo無法執行
https://pypi.python.org/pypi/python-daemon

老式書寫後臺程序的一種方式

import time
import logging
import logging.handlers


logs = logging.getLogger('MyLogger')
logs.setLevel(logging.DEBUG)
fh = logging.handlers.RotatingFileHandler(
'/tmp/test.log',maxBytes=10000000,backupCount=5)
fh.setLevel(logging.DEBUG)
formatter = logging.Formatter(u'%(asctime)s [%(levelname)s] %(message)s')
fh.setFormatter(formatter)
logs.addHandler(fh)


while True:
for i in range(10):
logs.info("Beginning Scan {0}! \n".format(i))
time.sleep(1)

這樣並不能後臺執行，但是可以藉助linux的nohup和&。為此新增如下的啟動和停止指令碼，其實也不麻煩：

shell指令碼參見：http://t.cn/R8scWAe

$ sh startup.sh 
================================================================================================================
Starting older.py(PID=15315)...[Success]
================================================================================================================
$ sh startup.sh 
================================================================================================================
older.py already started(PID=15315)
================================================================================================================
$ sh shutdown.sh 
================================================================================================================
Stopping older.py(PID=15315)...[Success]
================================================================================================================
$ sh shutdown.sh 
================================================================================================================
older.py is not running
================================================================================================================

其他

supervisord 可以linux控制linux程序，當然也可以後臺化。

How do you create a daemon in Python?

另外也可以向linux systemd註冊為後臺程序。

python庫介紹-python-daemon: 實現python後臺程式的工具

簡介

快速入門

更實用的例子

參考資料

老式書寫後臺程序的一種方式

其他

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