Catch Keyboard Interrupt可停止Python多处理工作程序处理队列

Question

从stackoverflow上的几个帖子中，我创建了这段代码。

场景

我想要一个多访问队列，其中有几个工作人员"监听"

在键盘中断的情况下，主进程不应该再将新项目放入队列中，并且在sentinel对象的帮助下，工作程序应该优雅地停止。

问题

我使用的当前版本的问题

signal.signal(signal.SIGINT, signal.SIG_IGN) 

忽略Ctrl+C是指它也被主进程忽略。

有什么想法吗？我需要使用多处理工作池吗？一些例子表明我可能不得不这样做。那么我还能使用队列吗？

from multiprocessing import Pool, Process,Queue
import time
import signal
# http://docs.python.org/3.1/library/multiprocessing.html#multiprocessing.Queue
# http://docs.python.org/3.1/library/multiprocessing.html#multiprocessing.Process

class Worker(Process):
    def __init__(self, queue,ident):
        super(Worker, self).__init__()
        # Ignore Signals
        signal.signal(signal.SIGINT, signal.SIG_IGN)
        self.queue= queue
        self.idstr= str(ident)
        print "Ident" + self.idstr
    def run(self):
        print 'Worker started'
        # do some initialization here
        print 'Computing things!'
        for data in iter( self.queue.get, None ):
            print "#" + self.idstr + " : " + str(data)
            time.sleep(5)
            print "#" + self.idstr + "Queue Size: " + str(self.queue.qsize())
        print "Worker Done"
#### Main ####
request_queue = Queue(10)
for i in range(4):
    Worker( request_queue,i ).start()
try:
    for data in range(1000000):
        request_queue.put( data )
        #print "Queue Size: " + str(request_queue.qsize())
        # Sentinel objects to allow clean shutdown: 1 per worker.
    for i in range(4):
        request_queue.put( None ) 
except KeyboardInterrupt:
    print "Caught KeyboardInterrupt, terminating workers"
    while  request_queue.empty()==False:
         request_queue.get()
    request_queue.put( None )    

Answer 1

基于您的解决方案（这很好），我添加了一层额外的保护层，以防主代码没有响应，用户取消两次：

global STOP
import os, signal
def signal_handler(sig, frame):
    global STOP
    if STOP:
        signal.signal(signal.SIGINT, signal.SIG_IGN)
        os.kill(os.getpid(), signal.SIGTERM)
    STOP = True
signal.signal(signal.SIGINT, signal_handler)

Answer 2

我想我找到了一个解决方案。尽管如此，我还是不喜欢我从main得到1次SIGINT，从Worker得到4次，但也许我不得不接受这一点。

1. 我为中断信号指定了一个信号处理程序。

2. 在接收到第一个Sig INT之后，我忽略更多的Sig INT信号

3. 我将停止标志切换为TRUE

4. 我打破了队列插入循环

5. 我调用停止功能，它清除队列并插入的停止哨兵

   from multiprocessing import Pool, Process,Queue
   import time
   import signal
   # http://docs.python.org/3.1/library/multiprocessing.html#multiprocessing.Queue
   # http://docs.python.org/3.1/library/multiprocessing.html#multiprocessing.Process
   # Stop Flag for loop
   stop = False
   # Define SIGINT
   def signal_handler(sig, frame):
       print 'You pressed Ctrl+C!'
       global stop
       stop = True
       # Ignore more Ctrl+C
       signal.signal(signal.SIGINT, signal.SIG_IGN) 
   signal.signal(signal.SIGINT, signal_handler)
   def stopSentinel(request_queue):
       print "CTRL Stop Queue and insert None"
       # Empty Existing Queue
       while  request_queue.empty()==False:
           request_queue.get()
       # Put One None for each Worker
       for i in range(4):
           request_queue.put( None ) 
   
   class Worker(Process):
       def __init__(self, queue,ident):
           super(Worker, self).__init__()
           self.queue= queue
           self.idstr= str(ident)
           print "Ident" + self.idstr
       def run(self):
           print 'Worker started'
           # do some initialization here
           print 'Computing things!'
           for data in iter( self.queue.get, None ):
               print "#" + self.idstr + " : " + str(data)
               time.sleep(5)
               print "#" + self.idstr + "Queue Size: " + str(self.queue.qsize())
           print "Worker Done"
   
   #### Main #####
   request_queue = Queue(10)
   for i in range(4):
       Worker( request_queue, i ).start()
   #### Fill Queue with Data ####
   for data in range(1000000):
       request_queue.put( data )
       #print "Queue Size: " + str(request_queue.qsize())
       # Sentinel objects to allow clean shutdown: 1 per worker.
       # Check for Stop
       print "Check Breakout"
       if stop == True:
           print "Stop Break"
           break
   if stop == True:
       stopSentinel(request_queue)
   else:       
       print "Normal Stop" 
       for i in range(4):
           request_queue.put( None )