# tf.VariableSynchronization

<br />

|---|---|
| [![](https://www.tensorflow.org/images/tf_logo_32px.png) TensorFlow 1 version](https://www.tensorflow.org/versions/r1.15/api_docs/python/tf/VariableSynchronization) | [![](https://www.tensorflow.org/images/GitHub-Mark-32px.png) View source on GitHub](https://github.com/tensorflow/tensorflow/blob/v2.0.0/tensorflow/python/ops/variables.py#L71-L88) |

Indicates when a distributed variable will be synced.

#### View aliases


**Compat aliases for migration**

See
[Migration guide](https://www.tensorflow.org/guide/migrate) for
more details.

[`tf.compat.v1.VariableSynchronization`](https://www.tensorflow.org/api_docs/python/tf/VariableSynchronization)

<br />

- `AUTO`: Indicates that the synchronization will be determined by the current `DistributionStrategy` (eg. With `MirroredStrategy` this would be `ON_WRITE`).
- `NONE`: Indicates that there will only be one copy of the variable, so there is no need to sync.
- `ON_WRITE`: Indicates that the variable will be updated across devices every time it is written.
- `ON_READ`: Indicates that the variable will be aggregated across devices when it is read (eg. when checkpointing or when evaluating an op that uses the variable).

## Class Variables

- `AUTO`
- `NONE`
- `ON_READ`
- `ON_WRITE`