Python守护进程和脚本单例运行详解

#!/usr/bin/env python #coding: utf-8 import sys, os  '''将当前进程fork为一个守护进程   注意：如果你的守护进程是由inetd启动的，不要这样做！inetd完成了   所有需要做的事情，包括重定向标准文件描述符，需要做的事情只有chdir()和umask()了 '''  def daemonize (stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'):    #重定向标准文件描述符（默认情况下定向到/dev/null）   try:      pid = os.fork()       #父进程(会话组头领进程)退出，这意味着一个非会话组头领进程永远不能重新获得控制终端。     if pid > 0:       sys.exit(0)  #父进程退出   except OSError, e:      sys.stderr.write ("fork #1 failed: (%d) %s/n" % (e.errno, e.strerror) )     sys.exit(1)     #从母体环境脱离   os.chdir("/") #chdir确认进程不保持任何目录于使用状态，否则不能umount一个文件系统。也可以改变到对于守护程序运行重要的文件所在目录   os.umask(0)  #调用umask(0)以便拥有对于写的任何东西的完全控制，因为有时不知道继承了什么样的umask。   os.setsid()  #setsid调用成功后，进程成为新的会话组长和新的进程组长，并与原来的登录会话和进程组脱离。     #执行第二次fork   try:      pid = os.fork()      if pid > 0:       sys.exit(0)  #第二个父进程退出   except OSError, e:      sys.stderr.write ("fork #2 failed: (%d) %s/n" % (e.errno, e.strerror) )     sys.exit(1)     #进程已经是守护进程了，重定向标准文件描述符    for f in sys.stdout, sys.stderr: f.flush()   si = open(stdin, 'r')   so = open(stdout, 'a+')   se = open(stderr, 'a+', 0)   os.dup2(si.fileno(), sys.stdin.fileno())  #dup2函数原子化关闭和复制文件描述符   os.dup2(so.fileno(), sys.stdout.fileno())   os.dup2(se.fileno(), sys.stderr.fileno())  #示例函数：每秒打印一个数字和时间戳 def main():   import time   sys.stdout.write('Daemon started with pid %d/n' % os.getpid())   sys.stdout.write('Daemon stdout output/n')   sys.stderr.write('Daemon stderr output/n')   c = 0   while True:     sys.stdout.write('%d: %s/n' %(c, time.ctime()))     sys.stdout.flush()     c = c+1     time.sleep(1)  if __name__ == "__main__":    daemonize('/dev/null','/tmp/daemon_stdout.log','/tmp/daemon_error.log')    main() 

#!/usr/bin/env python #coding: utf-8  #python模拟linux的守护进程  import sys, os, time, atexit, string from signal import SIGTERM  class Daemon:  def __init__(self, pidfile, stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'):    #需要获取调试信息，改为stdin='/dev/stdin', stdout='/dev/stdout', stderr='/dev/stderr'，以root身份运行。   self.stdin = stdin   self.stdout = stdout   self.stderr = stderr   self.pidfile = pidfile    def _daemonize(self):   try:    pid = os.fork()  #第一次fork，生成子进程，脱离父进程    if pid > 0:     sys.exit(0)   #退出主进程   except OSError, e:    sys.stderr.write('fork #1 failed: %d (%s)/n' % (e.errno, e.strerror))    sys.exit(1)     os.chdir("/")   #修改工作目录   os.setsid()    #设置新的会话连接   os.umask(0)    #重新设置文件创建权限     try:    pid = os.fork() #第二次fork，禁止进程打开终端    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)      #重定向文件描述符   sys.stdout.flush()   sys.stderr.flush()   si = file(self.stdin, 'r')   so = file(self.stdout, 'a+')   se = file(self.stderr, 'a+', 0)   os.dup2(si.fileno(), sys.stdin.fileno())   os.dup2(so.fileno(), sys.stdout.fileno())   os.dup2(se.fileno(), sys.stderr.fileno())      #注册退出函数，根据文件pid判断是否存在进程   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):    #检查pid文件是否存在以探测是否存在进程   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)      #启动监控   self._daemonize()   self._run()   def stop(self):   #从pid文件中获取pid   try:    pf = file(self.pidfile,'r')    pid = int(pf.read().strip())    pf.close()   except IOError:    pid = None     if not pid:  #重启不报错    message = 'pidfile %s does not exist. Daemon not running!/n'    sys.stderr.write(message % self.pidfile)    return     #杀进程   try:    while 1:     os.kill(pid, SIGTERM)     time.sleep(0.1)     #os.system('hadoop-daemon.sh stop datanode')     #os.system('hadoop-daemon.sh stop tasktracker')     #os.remove(self.pidfile)   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):   """ run your fun"""   while True:    #fp=open('/tmp/result','a+')    #fp.write('Hello World/n')    sys.stdout.write('%s:hello world/n' % (time.ctime(),))    sys.stdout.flush()     time.sleep(2)     if __name__ == '__main__':   daemon = Daemon('/tmp/watch_process.pid', stdout = '/tmp/watch_stdout.log')   if len(sys.argv) == 2:     if 'start' == sys.argv[1]:       daemon.start()     elif 'stop' == sys.argv[1]:       daemon.stop()     elif 'restart' == sys.argv[1]:       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) 

class MyDaemon(Daemon):   def run(self):     while True:       fp=open('/tmp/run.log','a+')       fp.write('Hello World/n')       time.sleep(1) 

#/bin/sh while true do  count=`ps -ef | grep "daemonclass.py" | grep -v "grep"`  if [ "$?" != "0" ]; then    daemonclass.py start  fi  sleep 2 done 

#!/usr/bin/env python #coding: utf-8 import fcntl, sys, time, os pidfile = 0  def ApplicationInstance():   global pidfile   pidfile = open(os.path.realpath(__file__), "r")   try:     fcntl.flock(pidfile, fcntl.LOCK_EX | fcntl.LOCK_NB) #创建一个排他锁,并且所被锁住其他进程不会阻塞   except:     print "another instance is running..."     sys.exit(1)  if __name__ == "__main__":   ApplicationInstance()   while True:     print 'running...'     time.sleep(1) 

#!/usr/bin/env python #coding: utf-8 import fcntl, sys, time pidfile = 0  def ApplicationInstance():   global pidfile   pidfile = open("instance.pid", "w")   try:     fcntl.lockf(pidfile, fcntl.LOCK_EX | fcntl.LOCK_NB) #创建一个排他锁,并且所被锁住其他进程不会阻塞   except IOError:     print "another instance is running..."     sys.exit(0)  if __name__ == "__main__":   ApplicationInstance()   while True:     print 'running...'     time.sleep(1) 

#!/usr/bin/env python #coding: utf-8 import time, os, sys import signal  pidfile = '/tmp/process.pid'  def sig_handler(sig, frame):   if os.path.exists(pidfile):     os.remove(pidfile)   sys.exit(0)  def ApplicationInstance():   signal.signal(signal.SIGTERM, sig_handler)   signal.signal(signal.SIGINT, sig_handler)   signal.signal(signal.SIGQUIT, sig_handler)    try:    pf = file(pidfile, 'r')    pid = int(pf.read().strip())    pf.close()   except IOError:    pid = None     if pid:    sys.stdout.write('instance is running.../n')    sys.exit(0)    file(pidfile, 'w+').write('%s/n' % os.getpid())  if __name__ == "__main__":   ApplicationInstance()   while True:     print 'running...'     time.sleep(1) 

#!/usr/bin/env python #coding: utf-8 import time, commands, signal, sys  def sig_handler(sig, frame):   if os.path.exists("/tmp/test"):     os.rmdir("/tmp/test")   sys.exit(0)  def ApplicationInstance():   signal.signal(signal.SIGTERM, sig_handler)   signal.signal(signal.SIGINT, sig_handler)   signal.signal(signal.SIGQUIT, sig_handler)   if commands.getstatusoutput("mkdir /tmp/test")[0]:     print "instance is running..."     sys.exit(0)  if __name__ == "__main__":   ApplicationInstance()   while True:     print 'running...'     time.sleep(1) 

import os import os.path import time     #class used to handle one application instance mechanism class ApplicationInstance:     #specify the file used to save the application instance pid   def __init__( self, pid_file ):     self.pid_file = pid_file     self.check()     self.startApplication()     #check if the current application is already running   def check( self ):     #check if the pidfile exists     if not os.path.isfile( self.pid_file ):       return     #read the pid from the file     pid = 0     try:       file = open( self.pid_file, 'rt' )       data = file.read()       file.close()       pid = int( data )     except:       pass     #check if the process with specified by pid exists     if 0 == pid:       return       try:       os.kill( pid, 0 )  #this will raise an exception if the pid is not valid     except:       return       #exit the application     print "The application is already running..."     exit(0) #exit raise an exception so don't put it in a try/except block     #called when the single instance starts to save it's pid   def startApplication( self ):     file = open( self.pid_file, 'wt' )     file.write( str( os.getpid() ) )     file.close()     #called when the single instance exit ( remove pid file )   def exitApplication( self ):     try:       os.remove( self.pid_file )     except:       pass     if __name__ == '__main__':   #create application instance   appInstance = ApplicationInstance( '/tmp/myapp.pid' )     #do something here   print "Start MyApp"   time.sleep(5)  #sleep 5 seconds   print "End MyApp"     #remove pid file   appInstance.exitApplication() 

#!/usr/bin/env python #coding: utf-8 import socket, time, sys   def ApplicationInstance():   try:       global s     s = socket.socket()     host = socket.gethostname()     s.bind((host, 60123))   except:     print "instance is running..."     sys.exit(0)  if __name__ == "__main__":   ApplicationInstance()   while True:     print 'running...'     time.sleep(1) 

#!/usr/bin/env python #coding: utf-8 import socket, time, sys import functools  #使用装饰器实现 def ApplicationInstance(func):   @functools.wraps(func)   def fun(*args,**kwargs):     import socket     try:       global s       s = socket.socket()       host = socket.gethostname()       s.bind((host, 60123))     except:       print('already has an instance...')       return None     return func(*args,**kwargs)   return fun  @ApplicationInstance def main():   while True:     print 'running...'     time.sleep(1)  if __name__ == "__main__":   main()