抓住Ctrl + C/SIGINT並在python中優雅地退出多進程

Question

如何在多進程python程序中捕獲Ctrl + C並正常退出所有進程，我需要解決方案在unix和windows上都能正常工作。我已經試過如下：

import multiprocessing 
import time 
import signal 
import sys 

jobs = [] 

def worker(): 
    signal.signal(signal.SIGINT, signal_handler) 
    while(True): 
     time.sleep(1.1234) 
     print "Working..." 

def signal_handler(signal, frame): 
    print 'You pressed Ctrl+C!' 
    # for p in jobs: 
    #  p.terminate() 
    sys.exit(0) 

if __name__ == "__main__": 
    for i in range(50): 
     p = multiprocessing.Process(target=worker) 
     jobs.append(p) 
     p.start() 

而且這樣的工作，但我不認爲這是正確的解決方案。

編輯： 這可能是this one

Answer 1

The previously accepted solution有競爭條件，它不起作用map和async函數。

處理正確的方法按Ctrl + C/SIGINT與multiprocessing.Pool是：

1. 使這一進程創建進程Pool之前忽略SIGINT。這種方式創建的子進程繼承了SIGINT處理程序。
2. 在創建了Pool之後，在父進程中恢復原始SIGINT處理程序。
3. 使用map_async和apply_async而不是阻止map和apply。
4. 等待結果超時，因爲默認阻止等待會忽略所有信號。這是Python bug https://bugs.python.org/issue8296。

將其組合在一起：

#!/bin/env python 
from __future__ import print_function 

import multiprocessing 
import os 
import signal 
import time 

def run_worker(delay): 
    print("In a worker process", os.getpid()) 
    time.sleep(delay) 

def main(): 
    print("Initializng 2 workers") 
    original_sigint_handler = signal.signal(signal.SIGINT, signal.SIG_IGN) 
    pool = multiprocessing.Pool(2) 
    signal.signal(signal.SIGINT, original_sigint_handler) 
    try: 
     print("Starting 2 jobs of 5 seconds each") 
     res = pool.map_async(run_worker, [5, 5]) 
     print("Waiting for results") 
     res.get(60) # Without the timeout this blocking call ignores all signals. 
    except KeyboardInterrupt: 
     print("Caught KeyboardInterrupt, terminating workers") 
     pool.terminate() 
    else: 
     print("Normal termination") 
     pool.close() 
    pool.join() 

if __name__ == "__main__": 
    main() 

如@YakovShklarov指出，存在的時間忽略的信號，並在父進程，在此期間，可以將信號丟失它取消忽略之間的窗口。改爲使用pthread_sigmask來臨時阻止父進程中的信號傳遞將阻止信號丟失，但是它在Python-2中不可用。

Answer 2

重複的解決方案是基於​​和this link，它解決了這個問題，我不得不搬到Pool雖然：

import multiprocessing 
import time 
import signal 
import sys 

def init_worker(): 
    signal.signal(signal.SIGINT, signal.SIG_IGN) 

def worker(): 
    while(True): 
     time.sleep(1.1234) 
     print "Working..." 

if __name__ == "__main__": 
    pool = multiprocessing.Pool(50, init_worker) 
    try: 
     for i in range(50): 
      pool.apply_async(worker) 

     time.sleep(10) 
     pool.close() 
     pool.join() 

    except KeyboardInterrupt: 
     print "Caught KeyboardInterrupt, terminating workers" 
     pool.terminate() 
     pool.join() 

Answer 3

剛在您的工作進程中處理KeyboardInterrupt-SystemExit異常：

def worker(): 
    while(True): 
     try: 
      msg = self.msg_queue.get() 
     except (KeyboardInterrupt, SystemExit): 
      print("Exiting...") 
      break