Python多处理退出错误

Question

当我按 Ctrl-C 退出我的应用程序时，我看到了这个

Error in atexit._run_exitfuncs:
Traceback (most recent call last):
  File "/usr/lib/python2.6/atexit.py", line 24, in _run_exitfuncs
    func(*targs, **kargs)
  File "/usr/lib/python2.6/multiprocessing/util.py", line 269, in _exit_function
    p.join()
  File "/usr/lib/python2.6/multiprocessing/process.py", line 119, in join
    res = self._popen.wait(timeout)
  File "/usr/lib/python2.6/multiprocessing/forking.py", line 117, in wait
    return self.poll(0)
  File "/usr/lib/python2.6/multiprocessing/forking.py", line 106, in poll
    pid, sts = os.waitpid(self.pid, flag)
OSError: [Errno 4] Interrupted system call
Error in sys.exitfunc:
Traceback (most recent call last):
  File "/usr/lib/python2.6/atexit.py", line 24, in _run_exitfuncs
    func(*targs, **kargs)
  File "/usr/lib/python2.6/multiprocessing/util.py", line 269, in _exit_function
    p.join()
  File "/usr/lib/python2.6/multiprocessing/process.py", line 119, in join
    res = self._popen.wait(timeout)
  File "/usr/lib/python2.6/multiprocessing/forking.py", line 117, in wait
    return self.poll(0)
  File "/usr/lib/python2.6/multiprocessing/forking.py", line 106, in poll
    pid, sts = os.waitpid(self.pid, flag)
OSError: [Errno 4] Interrupted system call

我在自己的东西上使用扭曲，

我用下面的代码注册了信号Ctrl-C

    def sigHandler(self, arg1, arg2):
        if not self.backuped:
            self.stopAll()
        else:
            out('central', 'backuped ALREADY, now FORCE exiting')
            exit()


    def stopAll(self):
        self.parserM.shutdown()
        for each in self.crawlM:
            each.shutdown()
        self.backup()
        reactor.stop()

当他们向其他人发出关机信号时，它会尝试告诉他们很好地关机通过

exit = multiprocessing.Event()
def shutdown(self):
    self.exit.set()

我所有的过程都以某种形式存在，

def run(self):
    while not self.exit.is_set():
        do something
    out('crawler', 'crawler exited sucessfully')

知道这个错误是什么吗？只有当我有一个特定线程的多个实例时，我才会得到它。

Answer 1

这与交互 OS 系统调用、信号以及它在多处理模块中的处理方式有关。我不太确定它是错误还是功能，但它处于有点棘手的领域，因为它是 python 与操作系统的交汇点。

问题是多处理在 waitpid 上阻塞，直到它正在等待的子进程终止。然而，由于您已经为 SIGINT 安装了一个信号处理程序并且您的程序获得了这个信号，它会中断系统调用以执行您的信号处理程序，并且 waitpid 退出表明它被信号中断了。 python 处理这种情况的方式是通过异常。

作为一种解决方法，您可以将有问题的部分包含在 while 循环和 try/catch block 中，就像这样，或者在您等待线程完成的地方，或者子类 multiprocessing.Popen:

import errno
from multiprocessing import Process

p = Process( target=func, args=stuff )
p.start()
notintr = False
while not notintr:
  try:
    p.join() # "Offending code"
    notintr = True
  except OSError, ose:
    if ose.errno != errno.EINTR:
      raise ose

要处理 multiprocessing.forking.Popen 你必须做这样的事情:

import errno
from multiprocessing import Process
from multiprocessing.forking import Popen
import os

# see /path/to/python/libs/multiprocessing/forking.py
class MyPopen(Popen):
  def poll(self, flag=os.WNOHANG): # from forking.py
    if self.returncode is None: # from forking.py
      notintr = False
      while not notintr:
        try:
          pid, sts = os.waitpid(self.pid, flag) # from forking.py
          notintr = True
        except OSError, ose:
          if ose.errno != errno.EINTR:
            raise ose
      # Rest of Popen.poll from forking.py goes here

p = Process( target=func args=stuff )
p._Popen = p
p.start()
p.join()