Sorry for the late reply. The 2.4 deadline kept us quite busy. About `StateStoreMigratedException`:
Why is it only thrown if the state is REBALANCING? A store might be migrated during a rebalance, and Kafka Streams might resume back to RUNNING state and afterward somebody tries to use an old store handle. Also, if state is REBALANCING, should we throw `StreamThreadRebalancingException`? Hence, I think `StateStoreMigratedException` does only make sense during `RUNNING` state. Why do we need to distinguish between `KafkaStreamsNotRunningException` and `StateStoreNotAvailableException`? Last, why do we distinguish between `KafkaStreams` instance and `StreamsThread`? To me, it seems we should always refer to the instance, because that is the level of granularity in which we enable/disable IQ atm. Last, for `StateStoreMigratedException`, I would add that a user need to rediscover the store and cannot blindly retry as the store handle is invalid and a new store handle must be retrieved. That is a difference to `StreamThreadRebalancingException` that allows for "blind" retries that either resolve (if the store is still on the same instance after rebalancing finishes, or changes to `StateStoreMigratedException` if the store was migrated away during rebalancing). -Matthias On 8/9/19 10:20 AM, Vito Jeng wrote: > My bad. The short link `https://shorturl.at/CDNT9` > <https://shorturl.at/CDNT9> seems incorrect. > > Please use the following instead: https://shorturl.at/bkKQU > > > --- > Vito > > > On Fri, Aug 9, 2019 at 10:53 AM Vito Jeng <v...@is-land.com.tw> wrote: > >> Thanks, Matthias! >> >>> About `StreamThreadNotStartedException`: >> >> Thank you for explanation. I agree with your opinion. >> `CompositeReadOnlyXxxStore#get()` would never throw >> `StreamThreadNotStartedException`. >> >> For the case that corresponding thread crashes after we handed out the >> store handle. We may throw `KafkaStreamsNotRunningException` or >> `StateStoreMigratedException`. >> In `StreamThreadStateStoreProvider`, we would throw >> `KafkaStreamsNotRunningException` when stream thread is not running( >> https://shorturl.at/CDNT9) or throw `StateStoreMigratedException` when >> store is closed(https://shorturl.at/hrvAN). So I think we do not need to >> add a new type for this case. Does that make sense? >> >> >>> About `KafkaStreamsNotRunningException` vs >> `StreamThreadNotRunningException`: >> >> I understand your point. I rename `StreamThreadNotRunningException` to >> `KafkaStreamsNotRunningException`. >> >> >> About check unknown state store names: >> Thank you for the hint. I add a new type `UnknownStateStoreException` for >> this case. >> >> >>> Also, we should still have fatal exception >> `StateStoreNotAvailableException`? Not sure why you remove it? >> >> Thank you point this, already add it again. >> >> The KIP already updated, please take a look. >> >> --- >> Vito >> >
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