python，进程之间消息、监控程序

外界调用向mgr进程发送消息，mgr根据不同消息启动或关闭相应进程（启动的进程，独占用，只启动一个）；
若有进程程退出 则mgr向外界发出信号。

外界代码：

点击(此处)折叠或打开

#!/usr/bin/python
#
# -*- coding:utf-8 -*-
#
#
import sys
import os
import subprocess
import signal
import time
import random

def sig_usr1(signum, frame):
  print("recive sinal from process(exited)")

signal.signal(signal.SIGUSR1, sig_usr1)

cmds= ['./mgr.py']
n =1
p = subprocess.Popen( cmds,stdin=subprocess.PIPE,stderr=subprocess.PIPE,close_fds=False)
while True:

    time.sleep(1)
    ret = p.poll()
    if ret is None:
      #print("main="+str(n))
      p.stdin.write(str(n)+"\n")
      p.stdin.flush()
      p.send_signal(signal.SIGUSR1)
      n = random.randint(1, 3)

print("main exit")

管理进程

#!/usr/bin/python
#
# -*- coding:utf-8 -*-
#

import sys
import os
import time
import signal
import subprocess

import json

data = {'num': 0, 'error': 0}

def getParentID():
  p=subprocess.Popen("ps -ef|grep tt.py|grep -v  grep|awk '{print $2}'",stdout=subprocess.PIPE,shell=True)
  ret = int(p.stdout.readline())
  return ret

par_id = getParentID()
print(par_id)
exe_process = 0
isRuning = True


def sig_usr1(signum, frame):
  ret = sys.stdin.readline()
  data['num'] = int(ret)


signal.signal(signal.SIGUSR1, sig_usr1)


while isRuning:
  time.sleep(1)

  print("data['num'] ="+str(data['num']))
  if exe_process == 0: #for open
    if data['num'] == 1:
      exe_process=subprocess.Popen("./a.out",close_fds=False)
    elif data['num'] == 2:
      exe_process=subprocess.Popen("./b.out",close_fds=False)
    else:
      continue
  else:  #if exe_process == 0: for close
    ret = exe_process.poll()
    if ret is None:
      if data['num'] == 3:
        exe_process.terminate()
        exe_process = 0
        os.kill(par_id,signal.SIGUSR1)

    else: #if ret is None   self close
      exe_process = 0
      print("end"+str(par_id))
      os.kill(par_id,signal.SIGUSR1)


print "mgr process over "

python进程通讯注意问题
1）发送信号： os.kill(par_id,signal.SIGUSR1)  #注意要 import os
2）subprocess结合管道要注意，不用就不要打开，否则容易出错
    比如p = subprocess.Popen(cmd,stdin=subprocess.PIPE,close_fds=False)
    stdin 要用到。
3）用subprocess调用Popen时候，cmd若是python脚本，要确保能编译通过并运行。则调用，否则不好排除错误