Fix reader of slim. (#2477)

* Fix reader of slim.

* Remove unused comments.

PaddleSlim/reader.py

@@ -133,6 +133,7 @@ def _reader_creator(file_list,
                     data_dir=DATA_DIR,
                     batch_size=1):
     def reader():
+        try:
             with open(file_list) as flist:
                 full_lines = [line.strip() for line in flist]
                 if shuffle:
@@ -142,24 +143,26 @@ def _reader_creator(file_list,
                     trainer_id = int(os.getenv("PADDLE_TRAINER_ID", "0"))
                     trainer_count = int(os.getenv("PADDLE_TRAINERS", "1"))
                     per_node_lines = len(full_lines) // trainer_count
-                lines = full_lines[trainer_id * per_node_lines:(trainer_id + 1)
-                                   * per_node_lines]
+                    lines = full_lines[trainer_id * per_node_lines:(
+                        trainer_id + 1) * per_node_lines]
                     print(
                         "read images from %d, length: %d, lines length: %d, total: %d"
-                    % (trainer_id * per_node_lines, per_node_lines, len(lines),
-                       len(full_lines)))
+                        % (trainer_id * per_node_lines, per_node_lines,
+                           len(lines), len(full_lines)))
                 else:
                     lines = full_lines
 
                 for line in lines:
                     if mode == 'train' or mode == 'val':
                         img_path, label = line.split()
-                    #                    img_path = img_path.replace("JPEG", "jpeg")
                         img_path = os.path.join(data_dir, img_path)
                         yield img_path, int(label)
                     elif mode == 'test':
                         img_path = os.path.join(data_dir, line)
                         yield [img_path]
+        except Exception as e:
+            print("Reader failed!\n{}".format(str(e)))
+            os._exit(1)
 
     mapper = functools.partial(
         process_image, mode=mode, color_jitter=color_jitter, rotate=rotate)