Python守护进程日志
[*]# -*- coding: utf-8 -*-
[*]import sys, os, time, atexit
[*]from signal import SIGTERM
[*]class Daemon:
[*] def __init__(self, pidfile, stderr='/data/deamon_err.log', stdout='/data/deamon_out.log', stdin='/dev/null'):
[*] self.stdin = stdin
[*] self.stdout = stdout
[*] self.stderr = stderr
[*] self.pidfile = pidfile
[*]
[*] def _daemonize(self):
[*] #脱离父进程
[*] try:
[*] pid = os.fork()
[*] if pid > 0:
[*] sys.exit(0)
[*] except OSError, e:
[*] sys.stderr.write("fork #1 failed: %d (%s)\n" % (e.errno, e.strerror))
[*] sys.exit(1)
[*]
[*] #脱离终端
[*] os.setsid()
[*] #修改当前工作目录
[*] os.chdir("/")
[*] #重设文件创建权限
[*] os.umask(0)
[*]
[*] #第二次fork，禁止进程重新打开控制终端
[*] try:
[*] pid = os.fork()
[*] if pid > 0:
[*] sys.exit(0)
[*] except OSError, e:
[*] sys.stderr.write("fork #2 failed: %d (%s)\n" % (e.errno, e.strerror))
[*] sys.exit(1)
[*]
[*] sys.stdout.flush()
[*] sys.stderr.flush()
[*] si = file(self.stdin, 'r')
[*] so = file(self.stdout, 'a+')
[*] se = file(self.stderr, 'a+', 0)
[*] #重定向标准输入/输出/错误
[*] os.dup2(si.fileno(), sys.stdin.fileno())
[*] os.dup2(so.fileno(), sys.stdout.fileno())
[*] os.dup2(se.fileno(), sys.stderr.fileno())
[*]
[*] #注册程序退出时的函数，即删掉pid文件
[*] atexit.register(self.delpid)
[*] pid = str(os.getpid())
[*] file(self.pidfile,'w+').write("%s\n" % pid)
[*]
[*] def delpid(self):
[*] os.remove(self.pidfile)
[*] def start(self):
[*] """
[*] Start the daemon
[*] """
[*] # Check for a pidfile to see if the daemon already runs
[*] try:
[*] pf = file(self.pidfile,'r')
[*] pid = int(pf.read().strip())
[*] pf.close()
[*] except IOError:
[*] pid = None
[*]
[*] if pid:
[*] message = "pidfile %s already exist. Daemon already running?\n"
[*] sys.stderr.write(message % self.pidfile)
[*] sys.exit(1)
[*]
[*] # Start the daemon
[*] self._daemonize()
[*] self._run()
[*] def stop(self):
[*] # Get the pid from the pidfile
[*] try:
[*] pf = file(self.pidfile,'r')
[*] pid = int(pf.read().strip())
[*] pf.close()
[*] except IOError:
[*] pid = None
[*]
[*] if not pid:
[*] message = "pidfile %s does not exist. Daemon not running?\n"
[*] sys.stderr.write(message % self.pidfile)
[*] return # not an error in a restart
[*] # Try killing the daemon process
[*] try:
[*] while 1:
[*] os.kill(pid, SIGTERM)
[*] time.sleep(0.1)
[*] except OSError, err:
[*] err = str(err)
[*] if err.find("No such process") > 0:
[*] if os.path.exists(self.pidfile):
[*] os.remove(self.pidfile)
[*] else:
[*] print str(err)
[*] sys.exit(1)
[*] def restart(self):
[*] self.stop()
[*] self.start()
[*] def _run(self):
[*]
[*]class MyDaemon(Daemon):
[*] def __init__(self, pidfile):
[*] mod_daemon.Daemon.__init__(self,pidfile)
[*] task_mgr_log = time.strftime('%Y%m%d') + '.log'
[*] self.logger = mod_logger.logger(task_mgr_log)
[*]
[*] def _run(self):
[*] self.logger.debug("begin sleep")
[*] time.sleep(20)
[*] self.logger.debug("end sleep")
[*]
[*]
[*]if __name__ == "__main__":
[*] daemon = MyDaemon('/tmp/daemon-example.pid')
[*] if len(sys.argv) == 2:
[*] if 'start' == sys.argv[1]:
[*] print 'start daemon'
[*] daemon.start()
[*] elif 'stop' == sys.argv[1]:
[*] print 'stop daemon'
[*] daemon.stop()
[*] elif 'restart' == sys.argv[1]:
[*] print 'restart daemon'
[*] daemon.restart()
[*] else:
[*] print "Unknown command"
[*] sys.exit(2)
[*] sys.exit(0)
[*] else:
[*] print "usage: %s start|stop|restart" % sys.argv[0]
[*] sys.exit(2)
最上面是守护进程的基类，只需使自己的类继承这个基类，并重写_run(self)方法，就可以让这个守护进程跑起来。这里需要注意几个地方：
1.因为守护进程是脱离了终端的，所以所有的stdout，stdin，stderr是不会输出到终端的，所以指定了stdout,stderr输出到日志文件。
2.自己的守护进程日志，需要在模块初始化的时候就一并初始化，而不能在_run方法的while循环中初始化，因为会导致日志句柄消耗过多，down掉程序。
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