text: Title: Distributed Training with 4 machines on Translation Task
  Body: Hello , I want to do distributed training using four machines ,each one has 8 1080ti GPUs on En-Zh translation task, and  the t2t-version is 1.6.5. I have seen the other similar issues , and 
   the distributed_training.md ,but  I still have some confusion. If the four machines named M1, M2 ,M3 ,M4 , the first step is to make the TF-Config. What I want is to make 4 machines to train together , thus I am not sure how to define the master and ps. And the second question is if four machines can do synchronous training ?
  Hope someone can give me some advice, thanks