def merge_fn(strategy,
value,
use_locking=False,
name=None,
read_value=True):
v = values_util.apply_aggregation(strategy, value, self._aggregation,
self)
if name and isinstance(name, values.PerReplica):
name = name.values[0]
return strategy.extended.update(
self,
f,
args=(v,),
kwargs={
"use_locking": use_locking,
"name": name,
"read_value": read_value
})
def merge_fn(strategy, value, **kwargs):
"""Aggregate values and update all variables in cross replica context."""
# Don't allow MEAN with non float dtype, since it may cause unexpected
# precision loss. Python3 and NumPy automatically upcast integers to
# float in division, but we should always preserve the type.
#
# Note that to be backward compatible we allow the case when the value
# is *always* the same on each replica. I.E. value is not a
# PerReplica. Refer to regroup() to see how values are grouped.
if self._aggregation == vs.VariableAggregation.MEAN and (
not self.dtype.is_floating) and isinstance(value, PerReplica):
raise ValueError(
"Cannot update non-float variables with "
"tf.VariableAggregation.MEAN aggregation in replica context. "
"Either change the variable dtype to float or update it in "
"cross-replica context.")
assert strategy == self.distribute_strategy
v = values_util.apply_aggregation(strategy, value, self.aggregation, self)
return self._update_cross_replica(update_fn, v, **kwargs)
