无法放到后台运行

当放到后台运行， 并且将日志重定向到文件中的时候就会报错：
```
self.handle_msg(r)
UnicodeEncodeError: 'ascii' codec can't encode character u'\u55e8' in position 7: ordinal not
```
看样子是编码错误， 但是放在终端里就可以正常运行， 输出重定向一下又不可以运行了是什么情况。

Start with the reported self.handle_msg(r) traceback and compare execution in a terminal with output redirected to a file. Reproduce the background-run case using the Chinese text shown, then identify the encoding behavior involved; done means redirected logging no longer raises UnicodeEncodeError.

Written by the indexing model from the issue text.