python - Celery: Executing a task after another task, but return the result of the first task

Question

Sometimes I need to run task B after task A, but return the result of task A. Looking at the docs, I have tried to (Avoid launching synchronous subtasks)

So I would use a chain, like this:

@celery.task
def A():
    return 5

@celery.task
def B():
    return 2

def do_all():
    chain = A.s() | B.s()
    chain()
    return result_of_A

But this would not work. In my case I need:

• B does not have any parameter. It does not accept the result of A
• B must be executed after A completes
• I do not need to wait for B to complete, and I do not need its result (B must be async?)
• How do I return the result of A in do_all? (A must be sync?)

Is it possible to implement this with chains or any other subtasks primitives?

Answer 1

我无法用原语来做这件事。可能有一个。但是另一种可行的方法是，使用任务 A 中的on_successorafter_return处理程序来启动任务 B。如果您还使用该ignore_result选项，那么任务 B 的调用将是真正的即发即弃。