解决AttributeError: module ‘tornado.web‘ has no attribute ‘asynchronous‘的问题

问题描述：

Python执行命令python manage.py celery -A HttpRunnerManager worker --loglevel=info启动worker，tornado报错：

AttributeError: module 'tornado.web' has no attribute 'asynchronous'

  File "C:\Python3.7.8\lib\site-packages\flower\api\tasks.py", line 83, in TaskApply
    @web.asynchronous
AttributeError: module 'tornado.web' has no attribute 'asynchronous'

原因分析：

查看python环境中安装的tornado版本，本机环境安装的是tornado6.0.4

查看官方文档了解到 tornado.web.asynchronous在tornado5.1版本中已弃用，并在tornado6.0中已删除，用coroutines代替。

Deprecated since version 5.1: This decorator is deprecated and will be removed in Tornado 6.0. Use coroutines instead.

官方说明文档https://www.tornadoweb.org/en/branch5.1/web.html#tornado.web.asynchronous

解决方法：

tornado6.0.4版本降级回到5.1.1就ok了

卸载命令：pip uninstall tornado

安装命令pip install tornado==5.1.1

参考：

https://github.com/tornadoweb/tornado/issues/2641

https://github.com/jupyter/nbconvert/issues/978