tf.distribute.experimental.ValueContext

A class wrapping information needed by a distribute function.

This is a context class that is passed to the value_fn in strategy.experimental_distribute_values_from_function and contains information about the compute replicas. The num_replicas_in_sync and replica_id can be used to customize the value on each replica.

Example usage:

  1. Directly constructed.

    def value_fn(context):
      return context.replica_id_in_sync_group/context.num_replicas_in_sync
    context = tf.distribute.experimental.ValueContext(
      replica_id_in_sync_group=2, num_replicas_in_sync=4)
    per_replica_value = value_fn(context)
    per_replica_value
        0.5
        
    
  2. Passed in by experimental_distribute_values_from_function.

    strategy = tf.distribute.MirroredStrategy(["GPU:0", "GPU:1"])
    def value_fn(value_context):
      return value_context.num_replicas_in_sync
    distributed_values = (
         strategy.experimental_distribute_values_from_function(
           value_fn))
    local_result = strategy.experimental_local_results(distributed_values)
    local_result
        (2, 2)
        
    

replica_id_in_sync_group the current replica_id, should be an int in [0,num_replicas_in_sync).
num_replicas_in_sync the number of replicas that are in sync.

num_replicas_in_sync Returns the number of compute replicas in sync.
replica_id_in_sync_group Returns the replica ID.