def aggregate_gradients(self, grads_and_vars):
"""Aggregate gradients on all devices.
By default we will perform reduce_sum of gradients across devices. Users can
implement their own aggregation logic by overriding this method.
Args:
grads_and_vars: List of (gradient, variable) pairs.
Returns:
List of (gradient, variable) pairs.
"""
return optimizer_utils.all_reduce_sum_gradients(grads_and_vars)
def _aggregate_gradients(self, grads_and_vars):
return optimizer_utils.all_reduce_sum_gradients(grads_and_vars)