Giridhar Addepalli commented on KAFKA-6645:

Thank you for your reply [~mjsax]

Can you please provide us with code pointer for this.

Is there some duration of time for which leader of consumer group waits for all 
the consumers to join the group ?

If Kafka Streams application is running on say 10 machines before, and we 
stopped the application on all machines now.

Now, say we are in the process of bringing up the application on the machines. 
During this it should not be the case that kafka streams thinks that other 
machines are down and try to assign partitions within the machines that are 
currently up.

> Host Affinity to facilitate faster restarts of kafka streams applications
> -------------------------------------------------------------------------
>                 Key: KAFKA-6645
>                 URL: https://issues.apache.org/jira/browse/KAFKA-6645
>             Project: Kafka
>          Issue Type: New Feature
>          Components: streams
>            Reporter: Giridhar Addepalli
>            Priority: Major
> Since Kafka Streams applications have lot of state in the stores in general, 
> it would be good to remember the assignment of partitions to machines. So 
> that when whole application is restarted for some reason, there is a way to 
> use past assignment of partitions to machines and there won't be need to 
> build up whole state by reading off of changelog kafka topic. This would 
> result in faster start-up.
> Samza has support for Host Affinity 
> ([https://samza.apache.org/learn/documentation/0.14/yarn/yarn-host-affinity.html])
> KIP-54 
> ([https://cwiki.apache.org/confluence/display/KAFKA/KIP-54+-+Sticky+Partition+Assignment+Strategy)]
>  , handles cases where some members of consumer group goes down / comes up, 
> and KIP-54 ensures there is minimal diff between assignments before and after 
> rebalance. 
> But to handle whole restart use case, we need to remember past assignment 
> somewhere, and use it after restart.
> Please let us know if this is already solved problem / some cleaner way of 
> achieving this objective

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