import tensorflow as tf

            tower_grads = []
            biases_regularizer = tf.no_regularizer
            weights_regularizer = tf.contrib.layers.l2_regularizer(cfgs.WEIGHT_DECAY)

            with tf.variable_scope(tf.get_variable_scope()):
                for i in range(num_gpu):
                    with tf.device('/gpu:%d' % i):
                        with tf.name_scope('tower_%d' % i):
