4、代理管理部分：

　　代理管理的主要任务是创建几个重要数据的队列，实例化每个agent并为其创建新的线程。代理管理会管理这个线程池，并在这些中重要的队列中获取到测试的结果；

　　重要代码：

     def run(self):
         self.running = True
         self.agents_started = False
         try:
             os.makedirs(self.output_dir， 0755)
         except OSError:
             self.output_dir = self.output_dir + time.strftime('/results_%Y.%m.%d_%H.%M.%S'， time.localtime())
             try:
                os.makedirs(self.output_dir， 0755)
             except OSError:
                 sys.stderr.write('ERROR: Can not create output directory ')
                 sys.exit(1)       
 
         # start thread for reading and writing queued results
         self.results_writer = ResultWriter(self.results_queue， self.output_dir)
         self.results_writer.setDaemon(True)
         self.results_writer.start()      
 
         for i in range(self.num_agents):
             spacing = float(self.rampup) / float(self.num_agents)
             if i > 0:  # first agent starts right away
                 time.sleep(spacing)
             if self.running:  # in case stop() was called before all agents are started
                 agent = LoadAgent(i， self.interval， self.log_msgs， self.output_dir， self.runtime_stats， self.error_queue， self.msg_queue， self.results_queue)
                 agent.start()
                 self.agent_refs.append(agent)
                 agent_started_line = 'Started agent ' + str(i + 1)
                 if sys.platform.startswith('win'):
                     sys.stdout.write(chr(0x08) * len(agent_started_line))  # move cursor back so we update the same line again
                     sys.stdout.write(agent_started_line)
                 else:
                     esc = chr(27) # escape key
                     sys.stdout.write(esc + '[G' )
                     sys.stdout.write(esc + '[A' )
                     sys.stdout.write(agent_started_line + ' ')
         if sys.platform.startswith('win'):
             sys.stdout.write(' ')
         print ' All agents running... '
         self.agents_started = True

     def stop(self):
         self.running = False
         for agent in self.agent_refs:
             agent.stop()       
 
         if WAITFOR_AGENT_FINISH:
             keep_running = True
             while keep_running:
                 keep_running = False
                 for agent in self.agent_refs:
                     if agent.isAlive():
                         keep_running = True
                         time.sleep(0.1)
 
         self.results_writer.stop()