简介
python-daemon实现Unix守护进程。 参考：PEP 3143
该库实现了PEP 3143“标准守护进程库”的良好行为守护进程规范。
DaemonContext实例保存程序的行为和配置的进程环境。
快速入门
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)
执行：
$ 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 Feb 8 14:21:43 2018
$ ps afx | grep -i daemon1
8646 pts/2 S+ 0:00 | \_ grep --color=auto -i daemon1
8640 ? S 0:00 \_ python3 daemon1.py
$ kill -9 8640
要想停止上述进程，可以通过ps查找到进程号，然后kill。
注意上述代码在python2没有任何问题，不过在python需要修改库文件runner.py打开文件的方式。
# 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)
更实用的例子
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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()
执行：
$ python2 daemon2.py
usage: daemon2.py start|stop|restart
$ python3 daemon2.py start
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.py stop
Terminating on signal 15
andrew@andrew-MS-7A71:~/code/python-chinese-library/libraries/daemon$ python3 daemon2.py stop
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
注意上面的错误是重复启动或者停止时进程并不存在导致的。
参考资料
- 本文相关书籍下载
- 本文涉及的python测试开发库 谢谢点赞！
- 本文代码地址
- 本文最新版本地址
- daemonize demo无法运行
- https://pypi.python.org/pypi/python-daemon
老式书写后台进程的一种方式
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)
这样并不能后台执行，但是可以借助linux的nohup和&。为此添加如下的启动和停止脚本，其实也不麻烦：
shell脚本参见： 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进程，当然也可以后台化。
How do you create a daemon in Python?
另外也可以向linux systemd注册为后台进程。
