芹菜中的任务依赖关系

Question

这样的任务依赖关系可能吗？ 1和2可以并行执行。 1a只能在1完成时执行，但如果1和2都完成，则可以执行12b。我知道我可以让1和2组成一组，然后组（1,2）| 12b可以是一个链条，但是如何使它成为1a在1完成后开始，无论2是怎么回事？

Answer 1

是的，这是可能的。这是一种方法。我用芹菜信号task_success连接到其触发celery task

my_tasks.py

from celery import Celery, task 
from celery.signals import task_success 

c = Celery('my_tasks') 

@task 
def t1(): 
    print('t1') 

@task 
def t2(): 
    print('t2') 

@task 
def t11(): 
    print('t11') 

@task 
def t12(): 
    print('t12') 

def trigger_task(*args, **kwargs): 
    t11.s().delay() 

task_success.connect(trigger_task, sender=t1) 

测试任务的函数：

In [6]: complex_task = chain(group(t1.s(), t2.s())(), t12.si().delay()) 

这里是日志。

[2014-10-10 12:31:05,082: INFO/MainProcess] Received task: my_tasks.t1[25dc70d2-263b-4e70-b9f2-56478bfedab5] 
[2014-10-10 12:31:05,083: INFO/MainProcess] Received task: my_tasks.t2[0b0c5eb6-78fa-4900-a605-5bfd55c0d309] 
[2014-10-10 12:31:05,084: INFO/MainProcess] Received task: my_tasks.t12[b08c616d-7a2d-4f7b-9298-2c8324b747ff] 
[2014-10-10 12:31:05,084: WARNING/Worker-1] t1 
[2014-10-10 12:31:05,084: WARNING/Worker-4] t2 
[2014-10-10 12:31:05,085: WARNING/Worker-3] t12 
[2014-10-10 12:31:05,086: INFO/MainProcess] Task my_tasks.t2[0b0c5eb6-78fa-4900-a605-5bfd55c0d309] succeeded in 0.00143978099914s: None 
[2014-10-10 12:31:05,086: INFO/MainProcess] Task my_tasks.t1[25dc70d2-263b-4e70-b9f2-56478bfedab5] succeeded in 0.00191083699974s: None 
[2014-10-10 12:31:05,087: INFO/MainProcess] Task my_tasks.t12[b08c616d-7a2d-4f7b-9298-2c8324b747ff] succeeded in 0.00184817300033s: None 
[2014-10-10 12:31:05,087: INFO/MainProcess] Received task: my_tasks.t11[a3e3f0c6-ac1f-4888-893a-02eee3b29585] 
[2014-10-10 12:31:05,088: WARNING/Worker-2] t11 
[2014-10-10 12:31:05,089: INFO/MainProcess] Task my_tasks.t11[a3e3f0c6-ac1f-4888-893a-02eee3b29585] succeeded in 0.000978848000159s: None 

我试图直接连接到任务，但it is throwing some error.