Fixes for multi-GPU continuous integration failures.

1) Test central storage strategy against numpy dataset.
2) Implement non-overridden methods from Variable in AggregatingVariable.
3) Make ResourceVariableSaveable support `is_resource_variable` instances.

PiperOrigin-RevId: 243518258

tensorflow/contrib/distribute/python/parameter_server_strategy_test.py

@@ -925,10 +925,10 @@ class CentralStorageStrategyTest(strategy_test_lib.DistributionTestBase,
   @combinations.generate(combinations.combine(mode=['graph', 'eager'],
                                               use_core_strategy=[True, False],
                                               required_gpus=2))
-  def testNumpyIterator(self, use_core_strategy):
+  def testNumpyDataset(self, use_core_strategy):
     strategy, _, _ = create_test_objects(
         num_gpus=2, use_core_strategy=use_core_strategy)
-    self._test_numpy_iterator(strategy)
+    self._test_numpy_dataset(strategy)
 
 
 if __name__ == '__main__':

tensorflow/python/distribute/values.py

@@ -1567,6 +1567,13 @@ class AggregatingVariable(variables_lib.Variable):
   def initializer(self):
     return self._v.initializer
 
+  @property
+  def op(self):
+    return self._v.op
+
+  def read_value(self):
+    return self._v.read_value()
+
   def eval(self, session=None):
     return self._v.eval(session)
 

tensorflow/python/training/saving/saveable_object_util.py

@@ -81,7 +81,7 @@ class ResourceVariableSaveable(saveable_object.SaveableObject):
     if isinstance(var, ops.Tensor):
       self.handle_op = var.op.inputs[0]
       tensor = var
-    elif isinstance(var, resource_variable_ops.ResourceVariable):
+    elif resource_variable_ops.is_resource_variable(var):
 
       def _read_variable_closure(v):
         def f():