<p>我试着用<a href="http://www.ibm.com/developerworks/aix/library/au-threadingpython/index.html" rel="nofollow">example</a>来理解。代码如下:</p>
<pre><code>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)
</code></pre>
<p>有时我会在这里得到这个错误:</p>
<p>线程thread-10中的异常(很可能在解释器关闭期间引发)</p>
<p>请解释一下是什么引起的。</p>
<p><strong>由其他作者更新:</strong></p>
<p>下面是我在类似代码中看到的完整异常:</p>
<pre><code>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
</code></pre>