键盘中断与python的多处理

Question

我正在使用python的多处理优雅地处理键盘中断问题

(是的,我知道Ctr-C不应该​​保证正常关闭 - 但是让我们讨论一个不同的线程)

考虑以下代码,其中我是用户a multiprocessing.Manager#list(),我理解的ListProxy处理列表的多进程访问.

当我使用Ctr-C时 - 我socket.error: [Errno 2] No such file or directory在尝试访问ListProxy时得到了一个

我希望共享列表不会在Ctr-C上被破坏.这可能吗？!

注意:我想在不使用池和队列的情况下解决此问题.

from multiprocessing import Process, Manager
from time import sleep

def f(process_number, shared_array):
    try:
        print "starting thread: ", process_number
        shared_array.append(process_number)
        sleep(3)
        shared_array.append(process_number)
    except KeyboardInterrupt:
        print "Keyboard interrupt in process: ", process_number
    finally:
        print "cleaning up thread", process_number

if __name__ == '__main__':

    processes = []

    manager = Manager()
    shared_array = manager.list()

    for i in xrange(4):
        p = Process(target=f, args=(i, shared_array))
        p.start()
        processes.append(p)

    try:
        for process in processes:
            process.join()
    except KeyboardInterrupt:
        print "Keyboard interrupt in main"

    for item in shared_array:
        # raises "socket.error: [Errno 2] No such file or directory"
        print item

如果你运行它,然后点击Ctr-C,我们得到以下内容:

starting thread:  0
starting thread:  1
starting thread:  3
starting thread:  2
^CKeyboard interupt in process:  3
Keyboard interupt in process:  0
cleaning up thread 3
cleaning up thread 0
Keyboard interupt in process:  1
Keyboard interupt in process:  2
cleaning up thread 1
cleaning up thread 2
Keyboard interupt in main
Traceback (most recent call last):
  File "multi.py", line 33, in <module>
    for item in shared_array:
  File "<string>", line 2, in __getitem__
  File "/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/multiprocessing/managers.py", line 755, in _callmethod
    self._connect()
  File "/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/multiprocessing/managers.py", line 742, in _connect
    conn = self._Client(self._token.address, authkey=self._authkey)
  File "/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/multiprocessing/connection.py", line 169, in Client
    c = SocketClient(address)
  File "/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/multiprocessing/connection.py", line 293, in SocketClient
    s.connect(address)
  File "/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/socket.py", line 224, in meth
    return getattr(self._sock,name)(*args)
socket.error: [Errno 2] No such file or directory

(这是使用multiprocessing.Lock具有类似影响的另一种方法... 要点)类似的问题:

• 捕获键盘中断以阻止Python多处理工作程序处理队列
• 键盘中断python的多处理池
• python多处理中的共享变量

Answer 1

multiprocessing.Manager()触发一个负责处理共享列表代理的子进程.

运行时的netstat输出:

unix 2 [ACC] STREAM LISTENING 3921657 8457/python/tmp/pymp-B9dcij/listener-X423Ml

这个由multiprocessing.Manager()创建的子进程捕获你的SIGINT并退出,导致与它相关的任何东西被解除引用,因此你的"没有这样的文件"错误(我还有其他几个错误取决于我何时决定发送SIGINT).

要解决此问题,您可以直接声明SyncManager对象(而不是让Manager()为您执行此操作).这将要求您使用start()方法实际启动子进程.start()方法将初始化函数作为其第一个参数(您可以在此处覆盖管理器的SIGINT).

下面的代码,尝试一下:

from multiprocessing import Process, Manager
from multiprocessing.managers import BaseManager, SyncManager
from time import sleep
import signal

#handle SIGINT from SyncManager object
def mgr_sig_handler(signal, frame):
    print 'not closing the mgr'

#initilizer for SyncManager
def mgr_init():
    signal.signal(signal.SIGINT, mgr_sig_handler)
    #signal.signal(signal.SIGINT, signal.SIG_IGN) # <- OR do this to just ignore the signal
    print 'initialized mananger'

def f(process_number, shared_array):
    try:
        print "starting thread: ", process_number
        shared_array.append(process_number)
        sleep(3)
        shared_array.append(process_number)
    except KeyboardInterrupt:
        print "Keyboard interrupt in process: ", process_number
    finally:
        print "cleaning up thread", process_number

if __name__ == '__main__':

    processes = []

     #using syncmanager directly instead of letting Manager() do it for me
    manager = SyncManager()
    manager.start(mgr_init)  #fire up the child manager process
    shared_array = manager.list()

    for i in xrange(4):
        p = Process(target=f, args=(i, shared_array))
        p.start()
        processes.append(p)

    try:
        for process in processes:
            process.join()
    except KeyboardInterrupt:
        print "Keyboard interrupt in main"

    for item in shared_array:
        print item