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()