在Python中使用子进程时,FileIO出现错误

我正在尝试生成一个日志文件,其中包含按顺序排列的信息。这就是我所拥有的:

class ExecThread(threading.Thread):
 def __init__(self, command):
  self.command = command
  self._lock = threading.Lock()
  threading.Thread.__init__ ( self )

 def run ( self ):
  self._lock.acquire()
  sys.stdout.write(''.join(["Executing: ",self.command,'\n']))
  log_file.write(''.join([self.command,'\n']))
  os.system(self.command)
  self._lock.release()

for ive in locate('*.ive', root_dir):
  command = "osgconv"
  command = ''.join([command,' ',"-O OutputTextureFiles",' ', infile,' ', outfile,' ',"2>&1"])

  conv_osg_thread = ExecThread(command)
  conv_osg_thread.start()
  conv_osg_thread.join()

我正在执行的命令在结尾处有此重定向:“2>&1" 当我运行这个程序时,我会在消息“Executing blah”之前得到子进程的输出,这个消息列在前面!我以为锁()能修好它,但是不行。