title: How run two different threads simultaneously in pyqt
body: <p>I have a situation where i need to start two threads one after the other. I tried the following code snippet, here i could able to start the Thread12 but not able to start Thread2. How can i start both....? 
  How to start 2 threads one ofter the other...?</p>
  
  <p><strong>Code snippet</strong></p>
  
  <pre><code>class Thread1(QtCore.QThread):
  
      Thread1Signal = QtCore.pyqtSignal(str)
  
      def __init__(self):
          super(Thread1, self).__init__()
  
      def run(self):
          print 'Thread1 started'
          While True:
  
              #some statments
              if Condition:
                  Thread1Signal.emit('Yes')
              else:
                  Thread1Signal.emit('No')
  
  class Thread2(QtCore.QThread):
  
      Thread2Signal = QtCore.pyqtSignal(str)
  
      def __init__(self):
          super(Thread2, self).__init__()
  
      def run(self):
          print 'Thread2 started'
          While True:
  
              #some statments
              if Condition:
                  Thread2Signal.emit('Yes')
              else:
                  Thread2Signal.emit('No')
  
  class MainClass(QtCore.QObject):
  
      MainSignal1 = QtCore.pyqtSignal(str)
      MainSignal2 = QtCore.pyqtSignal(str)
  
      def __init__(self):
          super(MainClass, self).__init__()   
  
          Threadinstance1 = Thread1()
          Threadinstance1.Thread1Signal.connect(MainSignal1)
  
          Threadinstance2 = Thread2()
          Threadinstance2.Thread2Signal.connect(MainSignal2)
  
  
     def start(self):
  
         Threadinstance1.start()
         Threadinstance2.start()                #Thread2 never starts.
  
  def signal1called(s):
  
      print s
  
  
  def signal2called(s):
  
      print s
  
  if __name__=='__main__':
      app = AtGui.QApplication(sys.argv)
      temp = MainClass()
      temp.MainSignal1.connect(signal1called)
      temp.MainSignal2.connect(signal2called)
      temp.start()
      sys.exit(app.exec()_)
  </code></pre>