Question

在下面的代码中，如果我将其中一个url更改为无效的内容，则整个进程将停止，并且我无法使用ctrl + c退出表单终端。所以我的问题是我应该如何在我的主线程运行方法中处理异常，如果发生错误会触发它并且在没有失败的情况下转到下一个列表元素：

#!/usr/bin/env python
import Queue
import threading
import urllib2
import time

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

queue = Queue.Queue()

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

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

            #grabs urls of hosts and prints first 1024 bytes of page
            url = urllib2.urlopen(host)
            print "connected"

            #signals to queue job is done
            self.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)
        t.setDaemon(True)
        t.start()


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

    #wait on the queue until everything has been processed
    queue.join()
main()
print "Elapsed Time: %s" % (time.time() - start)

Answer 1

使用finally块来确保线程始终发出信号，即使出现错误。

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

        #grabs urls of hosts and prints first 1024 bytes of page
        try:
            url = urllib2.urlopen(host)
            print "connected"
        except urllib2.URLError:
            print "couldn't connect to %s" % host

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

python线程异常导致停止进程

1 个答案: