- 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", "http://yahoo.com", "http://google.com", "http://amazon.com", "http://ibm.com", "http://apple.com"]#建立队列实例,此时队列为空#通过队列控制不同线程对数据的处理:#在数据出队之后某一线程再对其进行处理,保证队列中每个数据都只被一个线程处理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) : #队列中有10个数据要处理,但是
- for循环建立了5个子线程,#此时通过这里的
- while True无限循环,来保证每个子线程可以在处理完一个出队数据后继续处理剩余的数据#然后通过.setDaemon(True)来结束子线程
- while True: #grabs host from queue#若队列中无数据,则程序阻塞在这里不动,直到有数据入队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#若队列已满,则程序阻塞在这里不动,直到有数据出队self.out_queue.put(chunk)#signals to queue job is done#a: 每.task_done() 1次,.join()生成的总数减1 self.queue.task_done() class DatamineThread(threading.Thread) : """Threaded Url Grab"""def __init__(self, out_queue, i) : threading.Thread.__init__(self) self.out_queue = out_queue self.i = i def run(self) : while True: #grabs host from queue chunk = self.out_queue.get()#parse the chunk soup = BeautifulSoup(chunk)#查看哪个线程处理了哪个网站的数据print 'DatamineThread(%s)' % str(self.i),
- 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(3) : dt = DatamineThread(out_queue, i) dt.setDaemon(True) dt.start()#wait on the queue until everything has been processed#b: .join()的初始值为0,每入队1个数据,.join()的值加1#通过与#a合作,保证每一个入队的数据,都会完成相应的操作#待全部数据都完成操作、出队后,.join()的值也相应变为0,以继续主线程程序#类似线程模块中的.join() queue.join() out_queue.join() main() print "Elapsed Time: %s" % (time.time() - start)
来源: http://lib.csdn.net/snippet/python/41908