python – 多线程.线程中的异常
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我试图用example来理解.这是代码:
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)
有时我在这里得到这个错误:
线程Thread-10中的异常(很可能在解释器关闭期间引发)
请解释一下导致它的原因.
由另一位作者更新:
这是我在类似代码中看到的完整例外:
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
解决方法:
那是bug http://bugs.python.org/issue14623
最简单的解决方法是添加超时
time.sleep(1)
在脚本结束时允许线程在脚本结束并关闭之前完成
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