# tf.contrib.distribute.get_tower_context

tf.contrib.distribute.get_tower_context()


Returns the current TowerContext or None if in a cross-tower context.

Note that execution: 1. starts in the default (single-tower) tower context (this function will return the default TowerContext object); 2. switches to cross-tower context (in which case this will return None) when entering a with DistributionStrategy.scope(): block; 3. switches to a (non-default) tower context inside call_for_each_tower(fn, ...); 4. if fn calls get_tower_context()->merge_call(merge_fn, ...), then inside merge_fn you are back in the cross-tower context (and again this function will return None).

Note that you can also go directly from step 1 to 4 to switch to a cross-tower context for the default DistributionStrategy. You may also switch from the cross-tower context of 4 to a tower context by calling call_for_each_tower(), jumping back to step 3.

Most DistributionStrategy methods may only be executed in a cross-tower context, in a tower context you should use the TowerContext API instead.

#### Returns:

The current TowerContext object when in a tower context scope, else None.

Exactly one of get_tower_context() and get_cross_tower_context() will return None in a particular block.