fix trainer num for dist (#677)

demo/imagenet_reader.py

@@ -147,7 +147,7 @@ def _reader_creator(file_list,
                 if mode == 'train' and os.getenv('PADDLE_TRAINING_ROLE'):
                     # distributed mode if the env var `PADDLE_TRAINING_ROLE` exits
                     trainer_id = int(os.getenv("PADDLE_TRAINER_ID", "0"))
-                    trainer_count = int(os.getenv("PADDLE_TRAINERS", "1"))
+                    trainer_count = int(os.getenv("PADDLE_TRAINERS_NUM", "1"))
                     per_node_lines = len(full_lines) // trainer_count
                     lines = full_lines[trainer_id * per_node_lines:(
                         trainer_id + 1) * per_node_lines]
@@ -211,7 +211,7 @@ class ImageNetDataset(Dataset):
                 if os.getenv('PADDLE_TRAINING_ROLE'):
                     # distributed mode if the env var `PADDLE_TRAINING_ROLE` exits
                     trainer_id = int(os.getenv("PADDLE_TRAINER_ID", "0"))
-                    trainer_count = int(os.getenv("PADDLE_TRAINERS", "1"))
+                    trainer_count = int(os.getenv("PADDLE_TRAINERS_NUM", "1"))
                     per_node_lines = len(full_lines) // trainer_count
                     lines = full_lines[trainer_id * per_node_lines:(
                         trainer_id + 1) * per_node_lines]