服务器端close_wait模拟

服务端192.168.137.3上定义接口:
def testtimedout(req):
   time.sleep(20)
   out={"a":{'ip':'20.20.20.1','db':'aaa'},"c":{'ip':'1.1.1.1','db':'bbb'},"e":{'ip':'2.2.2.2','db':'cccc'}}
   return HttpResponse(json.dumps(out), content_type="application/json")
   

# !/usr/bin/env python
# -*- coding: utf-8 -*-
import urllib2
import urllib
import cookielib
import json
import httplib
import re
import requests
import os
import time
 
import requests, requests.utils, pickle
 
try:
    import cookielib  # 兼容Python2
except:
    import http.cookiejar as cookielib
 
from requests.packages.urllib3.exceptions import InsecureRequestWarning
 
requests.packages.urllib3.disable_warnings(InsecureRequestWarning)
url='http://192.168.137.3:9000/testtimedout'
while True:
   try:
    s = requests.session()
    r = s.get(url, verify=False,timeout=5)
    print r.content
   except:
       print '222222222'




服务器端:

Last login: Mon Aug 26 16:04:31 2019 from 192.168.137.1
node2:/root#netstat -na |grep 9000
tcp        0      0 0.0.0.0:9000                0.0.0.0:*                   LISTEN      



客户端:

C:UsersTLCB>netstat -na | findstr 9000

C:UsersTLCB>




# !/usr/bin/env python
# -*- coding: utf-8 -*-
import urllib2
import urllib
import cookielib
import json
import httplib
import re
import requests
import os
import time

import requests, requests.utils, pickle

try:
    import cookielib  # 兼容Python2
except:
    import http.cookiejar as cookielib

from requests.packages.urllib3.exceptions import InsecureRequestWarning

requests.packages.urllib3.disable_warnings(InsecureRequestWarning)
url = 'http://192.168.137.3:9000/testtimedout'
while True:
    try:
        s = requests.session()
        r = s.get(url, verify=False, timeout=5)
        print r.content
        r.close()
    except:
        print '222222222'




服务端close_wait
node2:/root#netstat -na |grep 9000 | grep -i close
tcp        1      0 192.168.137.3:9000          192.168.137.1:53583         CLOSE_WAIT  
tcp        1      0 192.168.137.3:9000          192.168.137.1:53578         CLOSE_WAIT  
tcp        1      0 192.168.137.3:9000          192.168.137.1:53598         CLOSE_WAIT  
tcp        1      0 192.168.137.3:9000          192.168.137.1:53571         CLOSE_WAIT  
tcp        1      0 192.168.137.3:9000          192.168.137.1:53586         CLOSE_WAIT  
tcp        1      0 192.168.137.3:9000          192.168.137.1:53574         CLOSE_WAIT  
tcp        1      0 192.168.137.3:9000          192.168.137.1:53588         CLOSE_WAIT  
tcp        1      0 192.168.137.3:9000          192.168.137.1:53592         CLOSE_WAIT  
tcp        1      0 192.168.137.3:9000          192.168.137.1:53596         CLOSE_WAIT  
node2:/root#netstat -na |grep 9000 | grep -i close | wc -l

客户端

C:UsersTLCB>netstat -na | findstr 9000
  TCP    192.168.137.1:54556    192.168.137.3:9000     FIN_WAIT_2
  TCP    192.168.137.1:54558    192.168.137.3:9000     FIN_WAIT_2
  TCP    192.168.137.1:54560    192.168.137.3:9000     FIN_WAIT_2
  TCP    192.168.137.1:54562    192.168.137.3:9000     FIN_WAIT_2
  TCP    192.168.137.1:54564    192.168.137.3:9000     FIN_WAIT_2
  TCP    192.168.137.1:54568    192.168.137.3:9000     FIN_WAIT_2
  TCP    192.168.137.1:54570    192.168.137.3:9000     FIN_WAIT_2
  TCP    192.168.137.1:54574    192.168.137.3:9000     FIN_WAIT_2
  TCP    192.168.137.1:54576    192.168.137.3:9000     FIN_WAIT_2
  TCP    192.168.137.1:54578    192.168.137.3:9000     FIN_WAIT_2
  TCP    192.168.137.1:54580    192.168.137.3:9000     FIN_WAIT_2
  TCP    192.168.137.1:54582    192.168.137.3:9000     FIN_WAIT_2
  TCP    192.168.137.1:54591    192.168.137.3:9000     FIN_WAIT_2
  TCP    192.168.137.1:54593    192.168.137.3:9000     FIN_WAIT_2
  TCP    192.168.137.1:54595    192.168.137.3:9000     FIN_WAIT_2
  TCP    192.168.137.1:54599    192.168.137.3:9000     FIN_WAIT_2
  
客户端主动关闭联系,服务端堵塞导致

servlet由于得不到数据库连接而阻塞了，这个客户端的请求就一直等待，客户端使用httpclient设置了5s的请求超时时间，


那么超时之后就会抛出异常，关闭连接，关闭连接导致客户端发送了FIN报文，


我这边的TCP/IP返回了ACK报文，但是由于处理请求的线程还处于阻塞的状态，所以当前的连接状态时CLOSE_WAIT。


发现这个状态是由于客户端关闭了socket连接，发送了FIN报文，服务端也发送了ACK报文，此时客户端处于FIN_WAIT_2状态，服务端处于CLOSE_WAIT状态，如下图：