Temporary disable async load data in PyDP2.

* It seems some other change breaks the async load. It will cause data
  error in GPU mode.

paddle/gserver/dataproviders/PyDataProvider2.cpp

@@ -647,7 +647,7 @@ public:
       DataBatch& gpuBatch = *batch;
       std::vector<Argument>& gpuArguments = gpuBatch.getStreams();
       gpuArguments.resize(cpuArguments.size());
-      gpuBatch.setSize(size);
+      gpuBatch.setSize(bsize);
       for (size_t i = 0; i < headers_.size(); ++i) {
         gpuArguments[i].resizeAndCopyFrom(
             cpuArguments[i], useGpu_, HPPL_STREAM_1);

python/paddle/trainer_config_helpers/data_sources.py

@@ -201,7 +201,7 @@ def define_py_data_sources2(train_list, test_list, module, obj, args=None):
         data.load_data_module = load_data_module
         data.load_data_object = load_data_object
         data.load_data_args = load_data_args
-        data.async_load_data = True
+        data.async_load_data = False
         return data
 
     define_py_data_sources(