如何在pyqt4中使用线程并行运行两个程序

import sys
from PyQt4.QtCore import QThread, pyqtSignal
from PyQt4.QtGui import QApplication

class MyThread(QThread):
    finished_signal = pyqtSignal()

    def run(self):
        # 在这里编写第一个程序的代码
        # ...

        self.finished_signal.emit()

def on_thread_finished():
    # 在这里编写第二个程序的代码
    # ...

app = QApplication(sys.argv)

thread1 = MyThread()
thread2 = MyThread()

thread1.finished_signal.connect(on_thread_finished)
thread2.finished_signal.connect(on_thread_finished)

# 启动两个线程
thread1.start()
thread2.start()

sys.exit(app.exec_())