file5 = 'ruisi\\httperror%s-%s.txt' % (startNum, endNum)
def safeGet(myid, myurl, seWord):
  try:
    return getInfo(myurl, seWord)
  except:
    try:
      return getInfo(myurl, seWord)
    except:
      httperrorfile = open(file5, 'a')
      info = '%d %s\n' % (myid, 'httperror')
      httperrorfile.write(info)
      httperrorfile.close()
      return 'httperror'

url1 = 'http://rs.xidian.edu.cn/home.php"htmlcode">

 sex = safeGet(id,sexUrl, sexRe)
 if not sex:
   sex = safeGet(id,timeUrl, sexRe)
 time = safeGet(id,timeUrl, timeRe)



这个代码如果断网的时候，调用了3次safeGet，每次调用都会往文本里面同一个id写多次httperror


251538 httperror
251538 httperror
251538 httperror
251538 httperror



多线程爬取信息？
数据统计可以用多线程，因为是独立的多个文本

1、Popen介绍
使用Popen可以自定义标准输入、标准输出和标准错误输出。我在SAP实习的时候，项目组在linux平台下经常使用Popen，可能是因为可以方便重定向输出。
下面这段代码借鉴了以前项目组的实现方法，Popen可以调用系统cmd命令。下面3个communicate()连在一起表示要等这3个线程都结束。
疑惑？ 

试验了一下，必须3个communicate()紧挨着才能保证3个线程同时开启，最后等待3个线程都结束。




p1=Popen(['python', 'ruisi.py', str(s0),str(s1)],bufsize=10000, stdout=subprocess.PIPE)

p2=Popen(['python', 'ruisi.py', str(s1),str(s2)],bufsize=10000, stdout=subprocess.PIPE)

p3=Popen(['python', 'ruisi.py', str(s2),str(s3)],bufsize=10000, stdout=subprocess.PIPE)

p1.communicate()
p2.communicate()
p3.communicate()




2、定义一个单线程的爬虫
用法：python ruisi.py <startNum> <endNum>
这段代码就是爬取[startNum, endNum)信息，输出到相应的文本里。它是一个单线程的程序，若要实现多线程的话，在外部调用它的地方实现多线程。



# ruisi.py
# coding=utf-8
import urllib2, re, sys, threading, time,thread

# myurl as 指定链接
# seWord as 正则表达式，用unicode表示
# 返回根据正则表达式匹配的信息或者None
def getInfo(myurl, seWord):
  headers = {
    'User-Agent': 'Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.6) Gecko/20091201 Firefox/3.5.6'
  }
  req = urllib2.Request(
    url=myurl,
    headers=headers
  )
  time.sleep(0.3)
  response = urllib2.urlopen(req)
  html = response.read()
  html = unicode(html, 'utf-8')
  timeMatch = seWord.search(html)
  if timeMatch:
    s = timeMatch.groups()
    return s[0]
  else:
    return None

#尝试两次getInfo()
#第2次失败后，就把这个id标记为httperror
def safeGet(myid, myurl, seWord):
  try:
    return getInfo(myurl, seWord)
  except:
    try:
      return getInfo(myurl, seWord)
    except:
      httperrorfile = open(file5, 'a')
      info = '%d %s\n' % (myid, 'httperror')
      httperrorfile.write(info)
      httperrorfile.close()
      return 'httperror'


#输出一个 idArr 范围，比如[1,1001)
def searchWeb(idArr):
  for id in idArr:
    sexUrl = url1 % (id)
    timeUrl = url2 % (id)
    sex = safeGet(id,sexUrl, sexRe)
    if not sex:
      sex = safeGet(id,timeUrl, sexRe)
    time = safeGet(id,timeUrl, timeRe)

    if (sex is 'httperror') or (time is 'httperror') :
      pass
    else:
      if sex:
        info = '%d %s' % (id, sex)
        if time:
          info = '%s %s\n' % (info, time)
          wfile = open(file1, 'a')
          wfile.write(info)
          wfile.close()
        else:
          info = '%s %s\n' % (info, 'notime')
          errtimefile = open(file2, 'a')
          errtimefile.write(info)
          errtimefile.close()
      else:
        notexist = safeGet(id,sexUrl, notexistRe)
        if notexist is 'httperror':
          pass
        else:
          if notexist:
            notexistfile = open(file3, 'a')
            info = '%d %s\n' % (id, 'notexist')
            notexistfile.write(info)
            notexistfile.close()
          else:
            unkownsexfile = open(file4, 'a')
            info = '%d %s\n' % (id, 'unkownsex')
            unkownsexfile.write(info)
            unkownsexfile.close()

def main():
  reload(sys)
  sys.setdefaultencoding('utf-8')
  if len(sys.argv) != 3:
    print 'usage: python ruisi.py <startNum> <endNum>'
    sys.exit(-1)
  global sexRe,timeRe,notexistRe,url1,url2,file1,file2,file3,file4,startNum,endNum,file5
  startNum=int(sys.argv[1])
  endNum=int(sys.argv[2])
  sexRe = re.compile(u'em>\u6027\u522b</em>(.*"htmlcode">

# coding=utf-8
from subprocess import Popen
import subprocess
import threading,time


startn = 1
endn = 300001
step =1000
total = (endn - startn + 1 ) /step
ISOTIMEFORMAT='%Y-%m-%d %X'

#hardcode 3 threads
#沒有深究3个线程好还是4或者更多个线程好
#输出格式化的年月日时分秒
#输出程序的耗时（以秒为单位）
for i in xrange(0,total,3):
  startNumber = startn + step * i
  startTime = time.clock()

  s0 = startNumber
  s1 = startNumber + step
  s2 = startNumber + step*2
  s3 = startNumber + step*3



  p1=Popen(['python', 'ruisi.py', str(s0),str(s1)],bufsize=10000, stdout=subprocess.PIPE)

  p2=Popen(['python', 'ruisi.py', str(s1),str(s2)],bufsize=10000, stdout=subprocess.PIPE)

  p3=Popen(['python', 'ruisi.py', str(s2),str(s3)],bufsize=10000, stdout=subprocess.PIPE)

  startftime ='[ '+ time.strftime( ISOTIMEFORMAT, time.localtime() ) + ' ] '

  print startftime + '%s - %s download start... ' %(s0, s1)
  print startftime + '%s - %s download start... ' %(s1, s2)
  print startftime + '%s - %s download start... ' %(s2, s3)

  p1.communicate()
  p2.communicate()
  p3.communicate()

  endftime = '[ '+ time.strftime( ISOTIMEFORMAT, time.localtime() ) + ' ] '
  print endftime + '%s - %s download end !!! ' %(s0, s1)
  print endftime + '%s - %s download end !!! ' %(s1, s2)
  print endftime + '%s - %s download end !!! ' %(s2, s3)

  endTime = time.clock()
  print "cost time " + str(endTime - startTime) + " s"
  time.sleep(5)




这儿是记录时间戳的日志：


"D:\Program Files\Python27\python.exe" E:/pythonProject/webCrawler/sum.py
[ 2015-11-23 11:31:15 ] 1 - 1001 download start... 
[ 2015-11-23 11:31:15 ] 1001 - 2001 download start... 
[ 2015-11-23 11:31:15 ] 2001 - 3001 download start... 
[ 2015-11-23 11:53:44 ] 1 - 1001 download end !!! 
[ 2015-11-23 11:53:44 ] 1001 - 2001 download end !!! 
[ 2015-11-23 11:53:44 ] 2001 - 3001 download end !!! 
cost time 1348.99480677 s
[ 2015-11-23 11:53:50 ] 3001 - 4001 download start... 
[ 2015-11-23 11:53:50 ] 4001 - 5001 download start... 
[ 2015-11-23 11:53:50 ] 5001 - 6001 download start... 
[ 2015-11-23 12:16:56 ] 3001 - 4001 download end !!! 
[ 2015-11-23 12:16:56 ] 4001 - 5001 download end !!! 
[ 2015-11-23 12:16:56 ] 5001 - 6001 download end !!! 
cost time 1386.06407734 s
[ 2015-11-23 12:17:01 ] 6001 - 7001 download start... 
[ 2015-11-23 12:17:01 ] 7001 - 8001 download start... 
[ 2015-11-23 12:17:01 ] 8001 - 9001 download start... 



上面是多线程的Log记录，从下面可以看出，1000个用户平均需要500s，一个id需要0.5s。500*300/3600 = 41.666666666667小时，大概需要两天的时间。 

我们再试验一次单线程爬虫的耗时，记录如下:


"D:\Program Files\Python27\python.exe" E:/pythonProject/webCrawler/sum.py
1 - 1001 download start... 
1 - 1001 download end !!! 
cost time 1583.65911889 s
1001 - 2001 download start... 
1001 - 2001 download end !!! 
cost time 1342.46874278 s
2001 - 3001 download start... 
2001 - 3001 download end !!! 
cost time 1327.10885725 s
3001 - 4001 download start... 



我们发现一次线程爬取1000个用户耗时的时间也需要1500s，而多线程程序是3*1000个用户耗时1500s。
故多线程确实能比单线程省很多时间。
Note: 

在getInfo(myurl, seWord)里有time.sleep(0.3)这样一段代码，是为了防止批判访问BBS，而被BBS拒绝访问。这个0.3s对于上文多线程和单线程的统计时间有影响。

最后附上原始的，没有带时间戳的记录。（加上时间戳，可以知道程序什么时候开始爬虫的，以应对线程卡死情况。）


"D:\Program Files\Python27\python.exe" E:/pythonProject/webCrawler/sum.py
1 - 1001 download start... 
1001 - 2001 download start... 
2001 - 3001 download start... 
1 - 1001 download end !!! 
1001 - 2001 download end !!! 
2001 - 3001 download end !!! 
cost time 1532.74102812 s
3001 - 4001 download start... 
4001 - 5001 download start... 
5001 - 6001 download start... 
3001 - 4001 download end !!! 
4001 - 5001 download end !!! 
5001 - 6001 download end !!! 
cost time 2652.01624951 s
6001 - 7001 download start... 
7001 - 8001 download start... 
8001 - 9001 download start... 
6001 - 7001 download end !!! 
7001 - 8001 download end !!! 
8001 - 9001 download end !!! 
cost time 1880.61513696 s
9001 - 10001 download start... 
10001 - 11001 download start... 
11001 - 12001 download start... 
9001 - 10001 download end !!! 
10001 - 11001 download end !!! 
11001 - 12001 download end !!! 
cost time 1634.40575553 s
12001 - 13001 download start... 
13001 - 14001 download start... 
14001 - 15001 download start... 
12001 - 13001 download end !!! 
13001 - 14001 download end !!! 
14001 - 15001 download end !!! 
cost time 1403.62795496 s
15001 - 16001 download start... 
16001 - 17001 download start... 
17001 - 18001 download start... 
15001 - 16001 download end !!! 
16001 - 17001 download end !!! 
17001 - 18001 download end !!! 
cost time 1271.42177906 s
18001 - 19001 download start... 
19001 - 20001 download start... 
20001 - 21001 download start... 
18001 - 19001 download end !!! 
19001 - 20001 download end !!! 
20001 - 21001 download end !!! 
cost time 1476.04122024 s
21001 - 22001 download start... 
22001 - 23001 download start... 
23001 - 24001 download start... 
21001 - 22001 download end !!! 
22001 - 23001 download end !!! 
23001 - 24001 download end !!! 
cost time 1431.37074164 s
24001 - 25001 download start... 
25001 - 26001 download start... 
26001 - 27001 download start... 
24001 - 25001 download end !!! 
25001 - 26001 download end !!! 
26001 - 27001 download end !!! 
cost time 1411.45186874 s
27001 - 28001 download start... 
28001 - 29001 download start... 
29001 - 30001 download start... 
27001 - 28001 download end !!! 
28001 - 29001 download end !!! 
29001 - 30001 download end !!! 
cost time 1396.88837788 s
30001 - 31001 download start... 
31001 - 32001 download start... 
32001 - 33001 download start... 
30001 - 31001 download end !!! 
31001 - 32001 download end !!! 
32001 - 33001 download end !!! 
cost time 1389.01316718 s
33001 - 34001 download start... 
34001 - 35001 download start... 
35001 - 36001 download start... 
33001 - 34001 download end !!! 
34001 - 35001 download end !!! 
35001 - 36001 download end !!! 
cost time 1318.16040825 s
36001 - 37001 download start... 
37001 - 38001 download start... 
38001 - 39001 download start... 
36001 - 37001 download end !!! 
37001 - 38001 download end !!! 
38001 - 39001 download end !!! 
cost time 1362.59222822 s
39001 - 40001 download start... 
40001 - 41001 download start... 
41001 - 42001 download start... 
39001 - 40001 download end !!! 
40001 - 41001 download end !!! 
41001 - 42001 download end !!! 
cost time 1253.62498539 s
42001 - 43001 download start... 
43001 - 44001 download start... 
44001 - 45001 download start... 
42001 - 43001 download end !!! 
43001 - 44001 download end !!! 
44001 - 45001 download end !!! 
cost time 1313.50461988 s
45001 - 46001 download start... 
46001 - 47001 download start... 
47001 - 48001 download start... 
45001 - 46001 download end !!! 
46001 - 47001 download end !!! 
47001 - 48001 download end !!! 
cost time 1322.32317331 s
48001 - 49001 download start... 
49001 - 50001 download start... 
50001 - 51001 download start... 
48001 - 49001 download end !!! 
49001 - 50001 download end !!! 
50001 - 51001 download end !!! 
cost time 1381.58027296 s
51001 - 52001 download start... 
52001 - 53001 download start... 
53001 - 54001 download start... 
51001 - 52001 download end !!! 
52001 - 53001 download end !!! 
53001 - 54001 download end !!! 
cost time 1357.78699459 s
54001 - 55001 download start... 
55001 - 56001 download start... 
56001 - 57001 download start... 
54001 - 55001 download end !!! 
55001 - 56001 download end !!! 
56001 - 57001 download end !!! 
cost time 1359.76377246 s
57001 - 58001 download start... 
58001 - 59001 download start... 
59001 - 60001 download start... 
57001 - 58001 download end !!! 
58001 - 59001 download end !!! 
59001 - 60001 download end !!! 
cost time 1335.47829775 s
60001 - 61001 download start... 
61001 - 62001 download start... 
62001 - 63001 download start... 
60001 - 61001 download end !!! 
61001 - 62001 download end !!! 
62001 - 63001 download end !!! 
cost time 1354.82727645 s
63001 - 64001 download start... 
64001 - 65001 download start... 
65001 - 66001 download start... 
63001 - 64001 download end !!! 
64001 - 65001 download end !!! 
65001 - 66001 download end !!! 
cost time 1260.54731607 s
66001 - 67001 download start... 
67001 - 68001 download start... 
68001 - 69001 download start... 
66001 - 67001 download end !!! 
67001 - 68001 download end !!! 
68001 - 69001 download end !!! 
cost time 1363.58255686 s
69001 - 70001 download start... 
70001 - 71001 download start... 
71001 - 72001 download start... 
69001 - 70001 download end !!! 
70001 - 71001 download end !!! 
71001 - 72001 download end !!! 
cost time 1354.17163074 s
72001 - 73001 download start... 
73001 - 74001 download start... 
74001 - 75001 download start... 
72001 - 73001 download end !!! 
73001 - 74001 download end !!! 
74001 - 75001 download end !!! 
cost time 1335.00425259 s
75001 - 76001 download start... 
76001 - 77001 download start... 
77001 - 78001 download start... 
75001 - 76001 download end !!! 
76001 - 77001 download end !!! 
77001 - 78001 download end !!! 
cost time 1360.44054978 s
78001 - 79001 download start... 
79001 - 80001 download start... 
80001 - 81001 download start... 
78001 - 79001 download end !!! 
79001 - 80001 download end !!! 
80001 - 81001 download end !!! 
cost time 1369.72662457 s
81001 - 82001 download start... 
82001 - 83001 download start... 
83001 - 84001 download start... 
81001 - 82001 download end !!! 
82001 - 83001 download end !!! 
83001 - 84001 download end !!! 
cost time 1369.95550676 s
84001 - 85001 download start... 
85001 - 86001 download start... 
86001 - 87001 download start... 
84001 - 85001 download end !!! 
85001 - 86001 download end !!! 
86001 - 87001 download end !!! 
cost time 1482.53886433 s
87001 - 88001 download start... 
88001 - 89001 download start... 
89001 - 90001 download start... 



以上就是关于python实现爬虫统计学校BBS男女比例的第二篇，重点介绍了多线程爬虫，希望对大家的学习有所帮助。