Tensorflow: list of tuples as placeholder

I want to use compute_gradients

and generate local gradients. These gradients should be averaged with several local gradients from other machines, after which it will be called apply_gradients

. I use 2 session.runs

to feed_dict

the second, which takes gradients. Since it apply_gradients

expects a list of tuples, I'm looking for an efficient way to do this.

This is how I create a list of tuple placeholders:

grads  = cifar10.train_part1(loss, global_step)

xx = [tf.placeholder(tf.float32, shape=grads[0][0].shape) for i in range(10)]
yy = [tf.placeholder(tf.float32, shape=grads[0][0].shape) for i in range(10)]


xyz = zip(xx,yy)

train_op = cifar10.train_part2(loss,global_step, xyz)

      

        
        
        
      

    

I am getting the following error:

NotImplementedError: ('Trying to optimize unsupported type ', tf.Tensor 'Placeholder_10:0' shape=(5, 5, 3, 64) dtype=float32)