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https://issues.apache.org/jira/browse/KAFKA-8755?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16912642#comment-16912642
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Chris Pettitt edited comment on KAFKA-8755 at 8/21/19 8:05 PM:
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BUG 2: not a bug. It was updating at the commit interval, no faster. But I now
have it only doing an update if the task is blocked on a newer consumer commit,
which reduces ~100 `consumer.committed` calls down to 1 during failover for
non-optimized topology. Optimized topology continues to do the update offset
call because it is "blocked" - that is the consumer committed offset prevents
any new records from playing and we have a backlog of records ready to go.
was (Author: cpettitt-confluent):
BUG 2: not a bug. It was updating at the commit interval, no faster. But I now
have it only doing an update if the task is blocked on a newer consumer commit,
which reduces ~100 `consumer.committed` calls down to 1 during failover. This
improves both the optimized and the non-optimized cases.
> Stand-by Task of an Optimized Source Table Does Not Write Anything to its
> State Store
> -------------------------------------------------------------------------------------
>
> Key: KAFKA-8755
> URL: https://issues.apache.org/jira/browse/KAFKA-8755
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Affects Versions: 2.4.0
> Reporter: Bruno Cadonna
> Assignee: Chris Pettitt
> Priority: Major
> Labels: newbie
> Attachments: StandbyTaskTest.java
>
>
> With the following topology:
> {code:java}
> builder.table(
> INPUT_TOPIC,
> Consumed.with(Serdes.Integer(), Serdes.Integer()),
> Materialized.<Integer, Integer, KeyValueStore<Bytes, byte[]>>as(stateName)
> )
> {code}
> and with topology optimization turned on, Kafka Streams uses the input topic
> {{INPUT_TOPIC}} as the change log topic for state store {{stateName}}. A
> stand-by task for such a topology should read from {{INPUT_TOPIC}} and should
> write the records to its state store so that the streams client that runs the
> stand-by task can take over the execution of the topology in case of a
> failure with an up-to-date replica of the state.
> Currently, the stand-by task described above reads from the input topic but
> does not write the records to its state store. Thus, after a failure the
> stand-by task cannot provide any up-to-date state store and the streams
> client needs to construct the state from scratch before it can take over the
> execution.
> The described behaviour can be reproduced with the attached test.
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