Defined in tensorflow/python/training/

Returns the current DistributionStrategy if in a cross-tower context.

Note that execution: 1. starts in the default (single-tower) tower context; 2. switches to cross-tower context 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.

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.


Returns the current DistributionStrategy object in a cross-tower context, or None.

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