Thinking more...

在查 Periodic task 為什麼沒執行，beat 是有發出訊息，但 task 卻沒被執行。在 worker log 裡找到

Received and deleted unknown message. Wrong destination

的訊息，查了以後，找到這些資料：

• Received and deleted unknown message. Wrong destination
• Celery &Rabbitmq:WARNING/MainProcess] Received and deleted unknown message. Wrong destination?!?
• Django / Celery / Kombu worker error: Received and deleted unknown message. Wrong destination?

所有的矛頭都指向 librabbitmq ，所以解法有兩種，一種是移除 librabbitmq，一種則是將 protocol 改為 1

 CELERY_TASK_PROTOCOL = 1