log read data

csst_dfs_api_cluster/msc/level1.py

@@ -159,6 +159,7 @@ class Level1DataApi(object):
             with open(rec.file_path, 'rb') as f:
                 while True:
                     data = f.read(UPLOAD_CHUNK_SIZE)
+                    print("read data len: %d" %(len(data),))
                     if not data:
                         break
                     yield level1_pb2.WriteLevel1Req(record = rec, data = data)