启动Celery报错：
kombu.exceptions.VersionMismatch: Redis transport requires redis-py versions 3.2.0 or later. You have 2.10.6
原因是我的redis版本太低了，和kombu不兼容。但是我不会去动我的redis的。
卸载当前的Celery 下载4.1.0版本的Celery（安装时会更新kombu）之后再次启动，报错：
pip install Celery==4.1.0 报错如下 KeyError: 'async'
问题是4.1.0版本的celery和python3.6.9不兼容，所以更换成4.1.1版本的Celery
pip install Celery==4.1.0
再次启动celery：
celery -A celery_task.main worker -l info
成功解决了
参考：
https://blog.csdn.net/Growing_hacker/article/details/98974894?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522165675457216782388060696%2522%252C%2522scm%2522%253A%252220140713.130102334.pc%255Fall.%2522%257D&request_id=165675457216782388060696&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2allfirst_rank_ecpm_v1~pc_rank_34-1-98974894-null-null.142v30pc_rank_34,185v2control&utm_term=kombu.exceptions.VersionMismatch%3A+Redis+transport+requires+redis-py+versions+3.2.0+or+later.+You+have+2.10.6&spm=1018.2226.3001.4187
https://blog.csdn.net/qq_34496399/article/details/102394230?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522165675485116782395340471%2522%252C%2522scm%2522%253A%252220140713.130102334.pc%255Fall.%2522%257D&request_id=165675485116782395340471&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2allfirst_rank_ecpm_v1~pc_rank_34-1-102394230-null-null.142v30pc_rank_34,185v2control&utm_term=KeyError%3A+async&spm=1018.2226.3001.4187
