Merge pull request #3082 from qingqing01/multi_gpu_infer

Fix bug for multi-GPU inference.

python/paddle/v2/inference.py

@@ -35,6 +35,13 @@ class Inference(object):
             name = param.getName()
             assert isinstance(val, api.Vector)
             val.copyFromNumpyArray(parameters.get(name).flatten())
+            # the setValueUpdated function is called in randomize, zeroMem,
+            # load function in paddle/parameter/Parameter.cpp. But in the
+            # inference mode, the setValueUpdated is never called, it will
+            # cause the parameter will not be dispatched
+            # in MultiGradientMachine for multi-GPU. So setValueUpdated is
+            # called here, but it's better to call this function in one place.
+            param.setValueUpdated()
         self.__gradient_machine__ = gm
         self.__data_types__ = topo.data_type()