Hi All,
We are using version 2.5.1 of kafka-streams with 3 application instances
deployed as 3 kubernetes pods.
It consumes from multiple topics, each with 6 partitions.
I would like to know if streams uses sticky partition assignor strategy
internally since we can't set it externally on streams.
My scenario is like this: during rolling upgrades
Step 1: 1 new pod comes up so there are 4 pods, with some partitions
assigned to newly created pod and k8s then deletes one of older pods, so it
is pod1, pod2, pod3 (older) and pod4 (newer). Then pod1 is deleted. So
ultimately pod2, pod3, pod4
Step 2: K8s then repeats same for another old pod i.e. create a new pod and
then delete old pod. So pod2, pod3, pod4, pod5 and then delete pod2. So
ultimately pod3, pod4 and pod5
The question I have here is: will kafka streams try to sticky with the
partitions assigned to newly created pods during all these rebalances i.e.
the partitions assigned to pod4 in step 1 will still be retained during
step 2 when another older pod gets deleted OR the partitions are reshuffled
on each rebalance whenever older pods get deleted. So during step 2, when
pod2 is deleted, the partitions assigned to pod4 in step 1 will also
reshuffle again or it will be there and any new partitions will only be
assigned?
