Attach patch v1. It addresses the problem by starting the second replica from a random interval after the first replica.

Reviewed the patch, looks good to me.

Just one question about the motivation: in normal settings where # brokers is larger than # replicas, even if the first replica of a partition is assigned to the same broker, their following replicas may not be assigned to the same broker as long as their partition id are not the same. Just from the example from the code: P1 of Topic1 and P5 of Topic2 could have their first replicas assigned to the same broker, while their following replicas are not assigned to the same brokers.

Thanks for the review. Committed to 0.8.

The issue is that for partitions from different topics whose first replica is assigned to the same broker, without this patch, their second replica is assigned to the same broker too.

Is the partition assignment mentioned in the comment above assignReplicasToBrokers valid after this change ?

It's still valid since the change only affects the partition assignment of different topics.

There is a lot of confusing index flipping logic there, do you mind adding some docs to explain that ? For example, its still unclear whether the second replica is assigned to an adjacent broker compared to first replica

Yes, the logic is a bit cryptic. I will add some more comments.

I think that as long as the secondShift is different for two partition, even if their first replica is assigned to the same broker their following replicas would not be possibly assigned to the same broker?