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https://issues.apache.org/jira/browse/IGNITE-19910?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17854683#comment-17854683
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Ivan Daschinsky commented on IGNITE-19910:
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[~timonin.maksim] Thanks for review, merged
> CDC through Kafka: refactor timeouts
> ------------------------------------
>
> Key: IGNITE-19910
> URL: https://issues.apache.org/jira/browse/IGNITE-19910
> Project: Ignite
> Issue Type: Task
> Components: extensions
> Reporter: Ilya Shishkov
> Assignee: Ivan Daschinsky
> Priority: Minor
> Labels: IEP-59, ise
>
> Currently, in CDC through Kafka applications, single timeout property
> ({{kafkaRequestTimeout)}} is used for all Kafka related operations instead of
> built-in timeouts of Kafka clients API (moreover, default value of 3 seconds
> does not correspond to Kafka clients defaults):
> ||Client||Timeout||Default value, s||
> |{{KafkaProducer}}|{{delivery.timeout.ms}}|120|
> |{{KafkaProducer}}|{{request.timeout.ms}}|30|
> |{{KafkaConsumer}}|{{default.api.timeout.ms}}|60|
> |{{KafkaConsumer}}|{{request.timeout.ms}}|30|
> Table below describes places where {{kafkaRequestTimeout}} is _explicitly
> specified_ as total operation timeout instead of using default timeouts:
> ||CDC application||API||Default value ||
> |ignite-cdc.sh:
> {{IgniteToKafkaCdcStreamer}}|{{KafkaProducer#send}}|{{delivery.timeout.ms}} *|
> |kafka-to-ignite.sh:
> {{KafkaToIgniteCdcStreamerApplier}}|{{KafkaConsumer#commitSync}}|{{default.api.timeout.ms}}|
> |kafka-to-ignite.sh:
> {{KafkaToIgniteCdcStreamerApplier}}|{{KafkaConsumer#close}}|{{KafkaConsumer#DEFAULT_CLOSE_TIMEOUT_MS}}
> (30s)|
> |kafka-to-ignite.sh:
> {{KafkaToIgniteMetadataUpdater}}|{{KafkaConsumer#partitionsFor}}|{{default.api.timeout.ms}}|
> |kafka-to-ignite.sh:
> {{KafkaToIgniteMetadataUpdater}}|{{KafkaConsumer#endOffsets}}|{{request.timeout.ms}}|
> \* - waits for future during specified timeout ({{kafkaRequestTimeout}}), but
> future fails itself if delivery timeout exceeded.
> *Timeouts for KafkaConsumer*
> All above methods will fail with an exception, when specified timeout
> exceeds, thus, specified timeout *_should not be too low_*.
> On the other hand, kafka-to-ignite.sh also invokes {{KafkaConsumer#poll}}
> with timeout {{kafkaRequestTimeout}}, which blocks until data will become
> available or specified timeout will expire [5]. So, {{#poll}} should be
> called quite often and we *_should not set too large timeout_* for it,
> otherwise, we can face with delays of replication, when some topic partitions
> have no new data. It is not desired behavior, because in this case some
> partitions will wait to be processed.
> *Kafka clients request retries*
> Each single request will be retried in case of {{request.timeout.ms}}
> exceeding [2, 4]. Behavior of retries is similar both for {{KafkaConsumer}}
> and {{KafkaProducer}}. Minimal amount of retries approximately equals to
> ratio of total operation timeout to {{request.timeout.ms}}. Total timeout is
> an explicitly specified argument of API method or default value (described in
> above tables).
> It is obvious, that currently {{kafkaRequestTimeout}} have to be N times
> greater, than {{request.timeout.ms}} in order to make request retries
> possible, i.e. most of time we have to override default value of 3s in CDC
> configuration.
> *Conclusion*
> # It seems, that the better approach is to rely only on built-in kafka
> clients timeouts, because kafka clients have already provided connection
> reliability features. These timeouts should be configured according to Kafka
> documentation.
> # {{kafkaRequestTimeout}} should be used only for {{KafkaConsumer#poll}},
> default value of 3s can remain the same.
> # As alternative to points 1,2 we can add separate timeout for
> {{KafkaConsumer#poll}}. Default timeouts for all other operations have to be
> increased.
> *PS*
> Described behaviour is actual for Kafka 2.7.
> ----
> Links:
> #
> https://kafka.apache.org/27/documentation.html#producerconfigs_delivery.timeout.ms
> #
> https://kafka.apache.org/27/documentation.html#producerconfigs_request.timeout.ms
> #
> https://kafka.apache.org/27/documentation.html#consumerconfigs_default.api.timeout.ms
> #
> https://kafka.apache.org/27/documentation.html#consumerconfigs_request.timeout.ms
> #
> https://kafka.apache.org/27/javadoc/org/apache/kafka/clients/consumer/KafkaConsumer.html#poll-java.time.Duration-
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