Question about the Reducer in the summary statistics framework

Dear all,

I have a question about the reducer in the summary statistics framework. I have multiple reducers which have the same epoch. However, I would like them to run in a certain sequence. For example, I would like the running sequence reducer1->reducer2->reducer3. I still want them to have the same epoch and remain synchronized. Does anyone know how can that be achieved?

Thanks a lot.


Are these built-in reducers or did you write your own? I’m curious as to why you need them run in a certain order.


I think you’re talking about calculations and not reducers? Take a look at the variance calculation…

# Reduced priority since this depends on the average
hook compose_resultvals_hook(result: ResultVal, rv1: ResultVal, rv2: ResultVal) &priority=-5

You can set the priority of your composition hook to force the values to compose in a specific order.


When you say, “reducer”, do you really mean “calculation”? Your example has only a single reducer attached to it. That result value in the callback will have the results for any reducers and their associated calculations in it.