一、delay函數或者apply_async函數的傳參問題
1、通過delay或者apply_async傳參數給異步任務的時候不能傳實例，否則會報錯raised unexpected: EncodeError(TypeError('<ExtractCashRecord: ExtractCashRecord object> is not JSON serializable，因為我傳的參數有一個是ExtractCashRecord這個類的實例。
二、任務重復執行
celery使用redis作為broker的話，apply_async的異步任務如果執行之間是延遲超過1小時的話，celery會重復發布任務，會導致任務重復執行。這個在官方文檔中有說明celery文檔
if a task isn’t acknowledged within the Visibility Timeout the task will be redelivered to another worker and executed.This causes problems with ETA/countdown/retry tasks where the time to execute exceeds the visibility timeout; in fact if that happens it will be executed again, and again in a loop.So you have to increase the visibility timeout to match the time of the longest ETA you’re planning to use.Note that Celery will redeliver messages at worker shutdown, so having a long visibility timeout will only delay the redelivery of ‘lost’ tasks in the event of a power failure or forcefully terminated workers.Periodic tasks won’t be affected by the visibility timeout, as this is a concept separate from ETA/countdown.You can increase this timeout by configuring a transport option with the same name:
app.conf.broker_transport_options = {'visibility_timeout': 43200}*
The value must be an int describing the number of seconds.
這個時候，我們就需要在配置文件里面增加一項，來增大visibility_timeout的時間
BROKER_TRANSPORT_OPTIONS = {'visibility_timeout': 43200}
或者
app.conf.broker_transport_options = {'visibility_timeout': 43200}