Python实现批量检测HTTP服务的状态

用Python实现批量测试一组url的可用性（可以包括HTTP状态、响应时间等）并统计出现不可用情况的次数和频率等。

类似的，这样的脚本可以判断某个服务的可用性，以及在众多的服务提供者中选择最优的。

需求以及脚本实现的功能如下：

1. 默认情况下，执行脚本会检测一组url的可用性。
2. 如果可用，返回从脚本所在的机器到HTTP服务器所消耗的时间和内容等信息。
3. 如果url不可用，则记录并提示用户，并显示不可用发生的时间。
4. 默认情况下，允许最大的错误次数是200，数目可以自定义，如果达到允许的最大错误次数，则在输出信息的最后，根据每一个url做出错误统计。
5. 如果用户手动停止脚本，则需要在输出信息的最后，根据每一个url做出错误统计。

脚本中涉及的一些技巧：

1. 使用gevent并发处理多个HTTP请求，多个请求之间无须等待响应（gevent还有很多使用技巧，可再自行学习）；
2. 使用signal模块捕获信号，如果捕获到则处理并退出，避免主进程接收到KeyboardInterrupt直接退出但无法处理的问题；
3. 注意留意脚本中关于统计次数方面的小技巧；

脚本运行效果图（ 如果图片看不清楚，请选择"在新标签页中打开图片" ）如下：

脚本如下：

    #!/usr/bin/python
    # encoding: utf-8
    # -*- coding: utf8 -*-
    """
    Created by PyCharm.
    File:    LinuxBashShellScriptForOps:testNoHttpResponseException,testHttpHostAvailability.py
    User:    Guodong
    Create Date:  2016/10/26
    Create Time:  12:09

    Function:
     test Http Host Availability

    Some helpful message:
     For CentOS: yum -y install python-devel python-pip; pip install gevent
     For Ubuntu: apt-get -y install python-dev python-pip; pip install gevent
     For Windows: pip install gevent
     """
    import signal
    import time
    import sys
    # execute some operations concurrently using python
    from gevent import monkey

    monkey.patch_all()
    import gevent
    import urllib2

    hosts = ['https://webpush.wx2.qq.com/cgi-bin/mmwebwx-bin/synccheck',
       'https://webpush.wx.qq.com/cgi-bin/mmwebwx-bin/synccheck', ]

    errorStopCounts = 200

    quit_flag = False
    statistics = dict()


    def changeQuit_flag(signum, frame):
     del signum, frame
     global quit_flag
     quit_flag = True
     print "Canceled task on their own by the user."


    def testNoHttpResponseException(url):
     tryFlag = True
     global quit_flag
     errorCounts = 0
     tryCounts = 0
     global statistics
     globalStartTime = time.time()
     while tryFlag:
      if not quit_flag:
       tryCounts += 1
       print('GET: %s' % url)
       try:
        startTime = time.time()
        resp = urllib2.urlopen(url) # using module 'request' will be better, request will return header info..
        endTime = time.time()
        data = resp.read()
        responseTime = endTime - startTime
        print '%d bytes received from %s. response time is: %s' % (len(data), url, responseTime)
        print "data received from %s at %d try is: %s" % (url, tryCounts, data)
        gevent.sleep(2)
       except urllib2.HTTPError as e:
        errorCounts += 1
        statistics[url] = errorCounts
        currentTime = time.strftime('%Y-%m-%d %H:%M:%S', time.localtime())
        print "HTTPError occurred, %s, and this is %d times(total) occurs on %s at %s." % (
         e, statistics[url], url, currentTime)

        if errorCounts >= errorStopCounts:
         globalEndTime = time.time()
         tryFlag = False
      else:
       globalEndTime = time.time()
       break

     for url in statistics:
      print "Total error counts is %d on %s" % (statistics[url], url)
      hosts.remove(url)
     for url in hosts:
      print "Total error counts is 0 on %s" % url
     globalUsedTime = globalEndTime - globalStartTime
     print "Total time use is %s" % globalUsedTime
     sys.exit(0)


    try:
     # Even if the user cancelled the task,
     # it also can statistics the number of errors and the consumption of time for each host.
     signal.signal(signal.SIGINT, changeQuit_flag)

     gevent.joinall([gevent.spawn(testNoHttpResponseException, host) for host in hosts])
    except KeyboardInterrupt:
     # Note: this line can NOT be reached, because signal has been captured!
     print "Canceled task on their own by the user."
     sys.exit(0)