多线程。线程中的异常

Question

我正在尝试通过一个例子来理解这个问题。以下是代码：

import Queue
import threading
import urllib2
import time
from BeautifulSoup import BeautifulSoup

hosts = ["http://yahoo.com", "http://google.com", "http://amazon.com",
"http://ibm.com", "http://apple.com"]

queue = Queue.Queue()
out_queue = Queue.Queue()

class ThreadUrl(threading.Thread):
    """Threaded Url Grab"""
    def __init__(self, queue, out_queue):
        threading.Thread.__init__(self)
        self.queue = queue
        self.out_queue = out_queue

    def run(self):
        while True:
            #grabs host from queue
            host = self.queue.get()

            #grabs urls of hosts and then grabs chunk of webpage
            url = urllib2.urlopen(host)
            chunk = url.read()

            #place chunk into out queue
            self.out_queue.put(chunk)

            #signals to queue job is done
            self.queue.task_done()

class DatamineThread(threading.Thread):
    """Threaded Url Grab"""
    def __init__(self, out_queue):
        threading.Thread.__init__(self)
        self.out_queue = out_queue

    def run(self):
        while True:
            #grabs host from queue
            chunk = self.out_queue.get()

            #parse the chunk
            soup = BeautifulSoup(chunk)
            print soup.findAll(['title'])

            #signals to queue job is done
            self.out_queue.task_done()

start = time.time()
def main():

    #spawn a pool of threads, and pass them queue instance
    for i in range(5):
        t = ThreadUrl(queue, out_queue)
        t.setDaemon(True)
        t.start()

    #populate queue with data
    for host in hosts:
        queue.put(host)

    for i in range(5):
        dt = DatamineThread(out_queue)
        dt.setDaemon(True)
        dt.start()


    #wait on the queue until everything has been processed
    queue.join()
    out_queue.join()

main()
print "Elapsed Time: %s" % (time.time() - start)

有时候我会在这里遇到这个错误：

线程 Thread-10 中出现异常（很可能是在解释器关闭时引发的）

请解释一下是什么导致了这个问题。

另一位作者的更新：

这是我在类似代码中看到的完整异常信息：

Exception in thread Thread-1 (most likely raised during interpreter shutdown):
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/threading.py", line 552, in __bootstrap_inner
  File "/usr/local/lib/python2.7/threading.py", line 505, in run
  File "mine.py", line 86, in run
  File "/usr/local/lib/python2.7/Queue.py", line 168, in get
  File "/usr/local/lib/python2.7/threading.py", line 237, in wait
<type 'exceptions.TypeError'>: 'NoneType' object is not callable

错误处理多线程并发编程代码调试解释器线程管理异常捕获线程异常

多线程。线程中的异常

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