diff --git a/mars/xlog/crypt/decode_mars_nocrypt_log_file.py b/mars/xlog/crypt/decode_mars_nocrypt_log_file.py
index db0661d31..adf49f152 100644
--- a/mars/xlog/crypt/decode_mars_nocrypt_log_file.py
+++ b/mars/xlog/crypt/decode_mars_nocrypt_log_file.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python3
 
 import sys
 import os
@@ -50,7 +50,8 @@ def IsGoodLogBuffer(_buffer, _offset, count):
     headerLen = 1 + 2 + 1 + 1 + 4 + crypt_key_len
 
     if _offset + headerLen + 1 + 1 > len(_buffer): return (False, 'offset:%d > len(buffer):%d'%(_offset, len(_buffer)))
-    length = struct.unpack_from("I", buffer(_buffer, _offset+headerLen-4-crypt_key_len, 4))[0]
+    pos = _offset+headerLen-4-crypt_key_len
+    length = struct.unpack_from("I", memoryview(_buffer)[pos:pos+4])[0]
     if _offset + headerLen + length + 1 > len(_buffer): return (False, 'log length:%d, end pos %d > len(buffer):%d'%(length, _offset + headerLen + length + 1, len(_buffer)))
     if MAGIC_END!=_buffer[_offset + headerLen + length]: return (False, 'log length:%d, buffer[%d]:%d != MAGIC_END'%(length, _offset + headerLen + length, _buffer[_offset + headerLen + length]))
 
@@ -81,7 +82,7 @@ def DecodeBuffer(_buffer, _offset, _outbuffer):
         if -1==fixpos: 
             return -1
         else:
-            _outbuffer.extend("[F]decode_log_file.py decode error len=%d, result:%s \n"%(fixpos, ret[1]))
+            _outbuffer.extend(b"[F]decode_log_file.py decode error len=%d, result:%s \n"%(fixpos, ret[1]))
             _offset += fixpos 
 
     magic_start = _buffer[_offset]
@@ -91,20 +92,24 @@ def DecodeBuffer(_buffer, _offset, _outbuffer):
             or MAGIC_SYNC_ZSTD_START==magic_start or MAGIC_SYNC_NO_CRYPT_ZSTD_START==magic_start or MAGIC_ASYNC_ZSTD_START==magic_start or MAGIC_ASYNC_NO_CRYPT_ZSTD_START==magic_start:
         crypt_key_len = 64
     else:
-        _outbuffer.extend('in DecodeBuffer _buffer[%d]:%d != MAGIC_NUM_START'%(_offset, magic_start))
+        _outbuffer.extend(b'in DecodeBuffer _buffer[%d]:%d != MAGIC_NUM_START'%(_offset, magic_start))
         return -1
 
     headerLen = 1 + 2 + 1 + 1 + 4 + crypt_key_len
-    length = struct.unpack_from("I", buffer(_buffer, _offset+headerLen-4-crypt_key_len, 4))[0]
+    pos = _offset+headerLen-4-crypt_key_len
+    length = struct.unpack_from("I", memoryview(_buffer)[pos:pos+4])[0]
     tmpbuffer = bytearray(length)
 
-    seq=struct.unpack_from("H", buffer(_buffer, _offset+headerLen-4-crypt_key_len-2-2, 2))[0]
-    begin_hour=struct.unpack_from("c", buffer(_buffer, _offset+headerLen-4-crypt_key_len-1-1, 1))[0]
-    end_hour=struct.unpack_from("c", buffer(_buffer, _offset+headerLen-4-crypt_key_len-1, 1))[0]
+    pos = _offset+headerLen-4-crypt_key_len-2-2
+    seq=struct.unpack_from("H", memoryview(_buffer)[pos:pos+2])[0]
+    pos = _offset+headerLen-4-crypt_key_len-1-1
+    begin_hour=struct.unpack_from("c", memoryview(_buffer)[pos:pos+1])[0]
+    pos = _offset+headerLen-4-crypt_key_len-1
+    end_hour=struct.unpack_from("c", memoryview(_buffer)[pos:pos+1])[0]
 
     global lastseq
     if seq != 0 and seq != 1 and lastseq != 0 and seq != (lastseq+1):
-        _outbuffer.extend("[F]decode_log_file.py log seq:%d-%d is missing\n" %(lastseq+1, seq-1))
+        _outbuffer.extend(b"[F]decode_log_file.py log seq:%d-%d is missing\n" %(lastseq+1, seq-1))
 
     if seq != 0:
         lastseq = seq
@@ -118,14 +123,14 @@ def DecodeBuffer(_buffer, _offset, _outbuffer):
             print("use wrong decode script")
         elif MAGIC_ASYNC_NO_CRYPT_ZSTD_START == _buffer[_offset]:
             decompressor = zstd.ZstdDecompressor()
-            tmpbuffer = next(decompressor.read_from(ZstdDecompressReader(str(tmpbuffer)), 100000, 1000000))
+            tmpbuffer = next(decompressor.read_to_iter(ZstdDecompressReader(bytes(tmpbuffer)), 100000, 1000000))
         elif MAGIC_COMPRESS_START==_buffer[_offset] or MAGIC_COMPRESS_NO_CRYPT_START==_buffer[_offset]:
             decompressor = zlib.decompressobj(-zlib.MAX_WBITS)
-            tmpbuffer = decompressor.decompress(str(tmpbuffer))
+            tmpbuffer = decompressor.decompress(tmpbuffer)
         elif MAGIC_COMPRESS_START1==_buffer[_offset]:
             decompress_data = bytearray()
             while len(tmpbuffer) > 0:
-                single_log_len = struct.unpack_from("H", buffer(tmpbuffer, 0, 2))[0]
+                single_log_len = struct.unpack_from("H", memoryview(tmpbuffer)[0:2])[0]
                 decompress_data.extend(tmpbuffer[2:single_log_len+2])
                 tmpbuffer[:] = tmpbuffer[single_log_len+2:len(tmpbuffer)]
 
@@ -136,7 +141,7 @@ def DecodeBuffer(_buffer, _offset, _outbuffer):
             pass
 
             # _outbuffer.extend('seq:%d, hour:%d-%d len:%d decompress:%d\n' %(seq, ord(begin_hour), ord(end_hour), length, len(tmpbuffer)))
-    except Exception, e:
+    except Exception as e:
         traceback.print_exc()  
         _outbuffer.extend("[F]decode_log_file.py decompress err, " + str(e) + "\n")
         return _offset+headerLen+length+1