Matthias, Thank you for your response.
I think you are right. We need to look at the state both of KafkaStreams and StreamThread. After further understanding of KafkaStreams thread and state store, I am currently rewriting the KIP. --- Vito On Fri, Dec 29, 2017 at 4:32 AM, Matthias J. Sax <matth...@confluent.io> wrote: > Vito, > > Sorry for this late reply. > > There can be two cases: > > - either a store got migrated way and thus, is not hosted an the > application instance anymore, > - or, a store is hosted but the instance is in state rebalance > > For the first case, users need to rediscover the store. For the second > case, they need to wait until rebalance is finished. > > If KafkaStreams is in state ERROR, PENDING_SHUTDOWN, or NOT_RUNNING, > uses cannot query at all and thus they cannot rediscover or retry. > > Does this make sense? > > -Matthias > > On 12/20/17 12:54 AM, vito jeng wrote: > > Matthias, > > > > I try to clarify some concept. > > > > When streams state is REBALANCING, it means the user can just plain > retry. > > > > When streams state is ERROR or PENDING_SHUTDOWN or NOT_RUNNING, it means > > state store migrated to another instance, the user needs to rediscover > the > > store. > > > > Is my understanding correct? > > > > > > --- > > Vito > > > > On Sun, Nov 5, 2017 at 12:30 AM, Matthias J. Sax <matth...@confluent.io> > > wrote: > > > >> Thanks for the KIP Vito! > >> > >> I agree with what Guozhang said. The original idea of the Jira was, to > >> give different exceptions for different "recovery" strategies to the > user. > >> > >> For example, if a store is currently recreated, a user just need to wait > >> and can query the store later. On the other hand, if a store go migrated > >> to another instance, a user needs to rediscover the store instead of a > >> "plain retry". > >> > >> Fatal errors might be a third category. > >> > >> Not sure if there is something else? > >> > >> Anyway, the KIP should contain a section that talks about this ideas and > >> reasoning. > >> > >> > >> -Matthias > >> > >> > >> On 11/3/17 11:26 PM, Guozhang Wang wrote: > >>> Thanks for writing up the KIP. > >>> > >>> Vito, Matthias: one thing that I wanted to figure out first is what > >>> categories of errors we want to notify the users, if we only wants to > >>> distinguish fatal v.s. retriable then probably we should rename the > >>> proposed StateStoreMigratedException / StateStoreClosedException > classes. > >>> And then from there we should list what are the possible internal > >>> exceptions ever thrown in those APIs in the call trace, and which > >>> exceptions should be wrapped to what others, and which ones should be > >>> handled without re-throwing, and which ones should not be wrapped at > all > >>> but directly thrown to user's face. > >>> > >>> Guozhang > >>> > >>> > >>> On Wed, Nov 1, 2017 at 11:09 PM, vito jeng <v...@is-land.com.tw> > wrote: > >>> > >>>> Hi, > >>>> > >>>> I'd like to start discuss KIP-216: > >>>> > >>>> https://cwiki.apache.org/confluence/display/KAFKA/KIP- > >>>> 216%3A+IQ+should+throw+different+exceptions+for+different+errors > >>>> > >>>> Please have a look. > >>>> Thanks! > >>>> > >>>> --- > >>>> Vito > >>>> > >>> > >>> > >>> > >> > >> > > > >
