同一任务多次执行 [英] Same task executed multiple times

问题描述

我有一些ETA任务，这些任务已发送给Celery的Redis经纪人.这是一个芹菜和Redis实例，都在同一台机器上.

I have ETA tasks that get sent to a Redis broker for Celery. It is a single celery and redis instance, both int he same machine.

问题是，任务被多次执行.我已经看到任务执行了4到11次.

The problem is, tasks are getting executed multiple times. I've seen tasks executed 4 to 11 times.

我将可见性超时设置为12小时，因为我的ETA在4-11小时之间(在运行时确定):

I set up the visibility timeout to be 12 hours, given that my ETA's are between 4-11 hours (determined at runtime):

BROKER_TRANSPORT_OPTIONS = {'visibility_timeout': 12 * 60 * 60}

即使如此，任务仍然会多次执行.

Even with that, tasks still get executed multiple times.

最初，有问题的任务不是幂等的，所以我尝试添加数据库检查以使其成为幂等的.

Initially, the task in question was not idempotent, so I tried adding in a DB check to make them idempotent.

它看起来像这样:

@app.task
def foo(side_effect_action):
    if side_effect_action.executed:
        return ALREADY_EXECUTED
    else:
        do_side_effect()
        side_effect_action.executed = True
        side_effect_action.save() #hits the db
        return JUST_EXECUTED

结果表明，芹菜工作者在foo能够调用 side_effect_action.save()并保存状态之前就开始执行任务，因此在所有情况下，当它正在寻找 side_effect_action.exected时，它仍然是False，因此被执行了多次.

Turns out that the celery worker gets to the task before foo is able to call side_effect_action.save() and save the state, so in all cases when it's looking for side_effect_action.executed it is still False, and thus gets executed multiple times.

任何想法如何解决此问题?

Any ideas how can I solve this issue?

推荐答案

为了避免这个问题，我将芹菜经纪人切换到RabbitMQ.不幸的是，因为现在我的Web应用程序中还有一个组件(我仍然需要redis来完成其他事情)，但是它确实解决了ETA任务多次执行错误.

I switched my celery broker to RabbitMQ to avoid this issue. It is unfortunate since I now have one more component in my webapp (I still need redis for something else), but it did solve the multiple execution for ETA tasks bug.

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