python支持多线程的爬虫实例

#!/usr/bin/env python
#coding=utf-8
import threading
import urllib
import re
import time
g_mutex=threading.Condition()
g_pages=[] #从中解析所有url链接
g_queueURL=[] #等待爬取的url链接列表
g_existURL=[] #已经爬取过的url链接列表
g_failedURL=[] #下载失败的url链接列表
g_totalcount=0 #下载过的页面数
class Crawler:
 def __init__(self,crawlername,url,threadnum):
  self.crawlername=crawlername
  self.url=url
  self.threadnum=threadnum
  self.threadpool=[]
  self.logfile=file("log.txt",'w')
 def craw(self):
  global g_queueURL
  g_queueURL.append(url) 
  depth=0
  print self.crawlername+" 启动..."
  while(len(g_queueURL)!=0):
   depth+=1
   print 'Searching depth ',depth,'...\n\n'
   self.logfile.write("URL:"+g_queueURL[0]+"........")
   self.downloadAll()
   self.updateQueueURL()
   content='\n>>>Depth '+str(depth)+':\n'
   self.logfile.write(content)
   i=0
   while i'+g_queueURL[i]+'\n'
    self.logfile.write(content)
    i+=1
 def downloadAll(self):
  global g_queueURL
  global g_totalcount
  i=0
  while i