初步理解Python进程的信号通讯

Python 2.4.3 (#1, Jun 11 2009, 14:09:58)

[GCC 4.1.2 20080704 (Red Hat 4.1.2-44)] on linux2

Type "help", "copyright", "credits" or "license" for more information.

> import signal

> dir(signal)

['NSIG', 'SIGABRT', 'SIGALRM', 'SIGBUS', 'SIGCHLD', 'SIGCLD', 'SIGCONT', 'SIGFPE', 'SIGHUP', 'SIGILL', 'SIGINT', 'SIGIO', 'SIGIOT', 'SIGKILL', 'SIGPIPE', 'SIGPOLL', 'SIGPROF', 'SIGPWR', 'SIGQUIT', 'SIGRTMAX', 'SIGRTMIN', 'SIGSEGV', 'SIGSTOP', 'SIGSYS', 'SIGTERM', 'SIGTRAP', 'SIGTSTP', 'SIGTTIN', 'SIGTTOU', 'SIGURG', 'SIGUSR1', 'SIGUSR2', 'SIGVTALRM', 'SIGWINCH', 'SIGXCPU', 'SIGXFSZ', 'SIG_DFL', 'SIG_IGN', '__doc__', '__name__', 'alarm', 'default_int_handler', 'getsignal', 'pause', 'signal']

  import os  
  import signal  
  from time import sleep  
     
  def onsignal_term(a,b):  
    print '收到SIGTERM信号'  
     
  #这里是绑定信号处理函数，将SIGTERM绑定在函数onsignal_term上面  
  signal.signal(signal.SIGTERM,onsignal_term)  
     
  def onsignal_usr1(a,b):  
    print '收到SIGUSR1信号'  
  #这里是绑定信号处理函数，将SIGUSR1绑定在函数onsignal_term上面  
  signal.signal(signal.SIGUSR1,onsignal_usr1)  
     
  while 1:  
    print '我的进程id是',os.getpid()  
    sleep(10)  

  import os  
  import signal  
     
  #发送信号，16175是前面那个绑定信号处理函数的pid，需要自行修改  
  os.kill(16175,signal.SIGTERM)  
  #发送信号，16175是前面那个绑定信号处理函数的pid，需要自行修改  
  os.kill(16175,signal.SIGUSR1)  

  ''''''' 
  子进程结束会向父进程发送SIGCHLD信号 
  '''  
  import os  
  import signal  
  from time import sleep  
     
  def onsigchld(a,b):  
    print '收到子进程结束信号'  
  signal.signal(signal.SIGCHLD,onsigchld)  
     
  pid = os.fork()  
  if pid == 0:  
    print '我是子进程,pid是',os.getpid()  
    sleep(2)  
  else:  
    print '我是父进程,pid是',os.getpid()  
    os.wait() #等待子进程结束  

  import os  
  import signal  
  from time import sleep  
  import Queue  
     
  QCOUNT = Queue.Queue() #初始化队列  
     
  def onsigchld(a,b):  
    '''''''收到信号后向队列中插入一个数字1'''  
    print '收到SIGUSR1信号'  
    sleep(2)  
    QCOUNT.put(1) #向队列中写入  
   
  def exithanddle(s,e): 
    raise SystemExit('收到终止命令,退出程序')  
   
  signal.signal(signal.SIGUSR1,onsigchld) #绑定信号处理函数  
  signal.signal(signal.SIGINT,exithanddle) #当按下Ctrl + C 终止进程 
     
  while 1:  
    print '我的pid是',os.getpid()  
    print '现在队列中元素的个数是',QCOUNT.qsize()  
    sleep(2) 

  ''''''' 
  使用多线程向另外一个进程发送信号 
  '''  
  import threading  
  import os  
  import signal  
     
  def sendusr1():  
    print '发送信号'  
    #这里的进程id需要写前一个程序实际运行的pid  
    os.kill(17788, signal.SIGUSR1)  
      
  WORKER = []  
     
  #开启6个线程  
  for i in range(1, 7):  
    threadinstance = threading.Thread(target = sendusr1)  
    WORKER.append(threadinstance)  
     
  for i in WORKER:  
    i.start()  
     
  for i in WORKER:  
    i.join()  
     
  print '主线程完成'  

  import signal 
  import time 
   
  def receive_alarm(signum, stack): 
    print 'Alarm :', time.ctime() 
   
  # Call receive_alarm in 2 seconds 
  signal.signal(signal.SIGALRM, receive_alarm) 
  signal.alarm(2) 
   
  print 'Before:', time.ctime() 
  time.sleep(10) 
  print 'After :', time.ctime()  

  import signal 
  import threading 
  import os 
  import time 
   
  def signal_handler(num, stack): 
    print 'Received signal %d in %s' % \ 
      (num, threading.currentThread().name) 
   
  signal.signal(signal.SIGUSR1, signal_handler) 
   
  def wait_for_signal(): 
    print 'Waiting for signal in', threading.currentThread().name 
    signal.pause() 
    print 'Done waiting' 
   
  # Start a thread that will not receive the signal 
  receiver = threading.Thread(target=wait_for_signal, name='receiver') 
  receiver.start() 
  time.sleep(0.1) 
   
  def send_signal(): 
    print 'Sending signal in', threading.currentThread().name 
    os.kill(os.getpid(), signal.SIGUSR1) 
   
  sender = threading.Thread(target=send_signal, name='sender') 
  sender.start() 
  sender.join() 
   
  # Wait for the thread to see the signal (not going to happen!) 
  print 'Waiting for', receiver.name 
  signal.alarm(2) 
  receiver.join() 

  import signal 
  import time 
  import threading 
   
  def signal_handler(num, stack): 
    print time.ctime(), 'Alarm in', threading.currentThread().name 
   
  signal.signal(signal.SIGALRM, signal_handler) 
   
  def use_alarm(): 
    t_name = threading.currentThread().name 
    print time.ctime(), 'Setting alarm in', t_name 
    signal.alarm(1) 
    print time.ctime(), 'Sleeping in', t_name 
    time.sleep(3) 
    print time.ctime(), 'Done with sleep in', t_name 
   
  # Start a thread that will not receive the signal 
  alarm_thread = threading.Thread(target=use_alarm, 
                  name='alarm_thread') 
  alarm_thread.start() 
  time.sleep(0.1) 
   
  # Wait for the thread to see the signal (not going to happen!) 
  print time.ctime(), 'Waiting for', alarm_thread.name 
  alarm_thread.join() 
   
  print time.ctime(), 'Exiting normally'