用Python实现多线程下载循环

Question

我有一个列表。

symbols = ('GGP', 'JPM', 'AIG', 'AMZN','GGP', 'rx', 'jnj', 'osip')

URL = "http://www.Xxxx_symbol=%s"

def fetch(symbols):
    try:
        url = URL % '+'.join(symbols)
        fp = urllib2.urlopen(url)
        try:
            data = fp.read()

        finally:
            fp.close()
        return data
    except Exception as e:
        print "No Internet Access" 

我想用4个线程来同时获取数据，而不是用多个进程，也不想用twisted这个库。获取的Url输出文件是csv格式，里面有7行头部信息，我想把这些去掉。我希望每个符号都能放在自己的文件里。我之前用过这个获取数据的代码，能得到一个只有一个元素的符号列表。

Answer 1

这段代码可以帮助你入门：

from threading import Thread, Lock

data = {}
data_lock = Lock()

class Fetcher(Thread):
    def __init__(self, symbol):
        super(Thread, self).__init__()
        Thread.__init__(self)
        self.symbol = symbol

    def run(self):
        # put the code from fetch() here
        # replace 'data = fp.read()' with the following
        tmp = fp.read()
        data_lock.acquire()
        data[self.symbol] = tmp
        data_lock.release()

# Start a new Fetcher thread like this:
fetcher = Fetcher(symbol)
fetcher.start()
# To wait for the thread to finish, use Thread.join():
fetcher.join()