remove redundant code, and make executor exit when set a illegal queue size

paddle/fluid/framework/async_executor.cc

@@ -143,8 +143,7 @@ void PrepareReaders(std::vector<std::shared_ptr<DataFeed> >& readers,
   readers.resize(thread_num);
   for (size_t i = 0; i < readers.size(); ++i) {
     readers[i] = DataFeedFactory::CreateDataFeed(data_feed_desc.name());
-    readers[i]->Init(data_feed_desc); // set batch size here
-    //readers[i]->SetQueueSize(32);   // default is 32
+    readers[i]->Init(data_feed_desc); // set batch_size and queue_size here
   }
   readers[0]->SetFileList(filelist);
 }

paddle/fluid/framework/data_feed.cc

@@ -60,7 +60,7 @@ bool DataFeed::SetFileList(const std::vector<std::string>& files) {
   CheckInit();
   if (files.size() == 0) {
     LOG(ERROR) << "error: you have set an empty filelist";
-    return false;
+    exit(-1);
   }
   filelist_.assign(files.begin(), files.end());
   file_idx_ = 0;
@@ -100,7 +100,7 @@ template<typename T>
 void PrivateQueueDataFeed<T>::SetQueueSize(int queue_size) {
   if (queue_size <= 0) {
     LOG(ERROR) << "error: illegal queue size: " << queue_size;
-    return;
+    exit(-1);
   }
   queue_size_ = queue_size;
   queue_.ReCap(queue_size_);