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890 строки
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890 строки
41 KiB
Plaintext
2022
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Udemy - Apache Kafka Series - Kafka Streams for Data Processing
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https://www.udemy.com/course/kafka-streams/
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magnet:?xt=urn:btih:302b50a873ad4f997158ecad2f79f4f3e92c19f0
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!!! 895m
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Apache Kafka Series - Learn Apache Kafka for Beginners v3
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https://www.udemy.com/course/apache-kafka/
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https://www.oreilly.com/library/view/apache-kafka-series/9781789342604/
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Udemy - Maarek - Apache Kafka Series - Learn Apache Kafka for Beginners v3
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magnet:?xt=urn:btih:b9bd6bbfb5193f69128c6c34db379821a58d4de2
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magnet:?xt=urn:btih:1485c91b36e8d099640dc6180dc42fd0e4a8997e
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magnet:?xt=urn:btih:6f08ccb2d05668fb929dded3c8a5744d5976e7e1
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https://freecoursesite.com/apache-kafka-series-learn-apache-kafka-for-beginners-v2-37/
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https://course-downloader.com/apache-kafka-series-learn-apache-kafka-for-beginners-v2-4463
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! 3.11g
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????
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Maarek - Apache Kafka Series – Learn Apache Kafka for Beginners v2
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magnet:?xt=urn:btih:d18a88e411d34c627db87450b5631eeaed6cc193
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magnet:?xt=urn:btih:b2f4b134238fb62b1cb06182178c348efe550cb5
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magnet:?xt=urn:btih:ab0be03d946ff2cf02d1f078ec1bcb43f6a884f0
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magnet:?xt=urn:btih:47dd77a975720aa74d108a7be5ef0ef100a8f55b
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magnet:?xt=urn:btih:15b04ee6ab7bc26708ff8d59f65526bd13d822e4
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magnet:?xt=urn:btih:e67fcb091584d050ba794c51e50cf3360682149d
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magnet:?xt=urn:btih:f33d7bf93e72baf68e50bb5c0cdb055d395729fe
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magnet:?xt=urn:btih:96e54381ee4af7b2c40e81c50143e94b759a99fa
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https://tutsnode.net/apache-kafka-series-learn-apache-kafka-for-beginners-v2/
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https://course-downloader.com/apache-kafka-series-learn-apache-kafka-for-beginners-v2-4425
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https://github.com/conduktor/kafka-beginners-course
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https://github.com/conduktor/kafka-stack-docker-compose
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https://raw.githubusercontent.com/conduktor/kafka-stack-docker-compose/master/zk-single-kafka-single.yml
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https://github.com/conduktor/conduktor-platform
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https://github.com/conduktor/conduktor-platform/tree/main/example-local
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! 3.16-10g
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Udemy - Apache Kafka Series - Confluent Schema Registry & REST Proxy
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https://www.udemy.com/course/confluent-schema-registry/
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magnet:?xt=urn:btih:d67f45d8e3240f47a8efb5650b5b1ad46dde5ede
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! 884.6m, 4h30m, interesting docker-compose
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landoop/fast-data-dev:cp3.3.0
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????
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2019
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Maarek - Learn Apache Kafka for Beginners
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! 7h32m
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/intro-to-apache-kafka
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https://github.com/simplesteph
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https://medium.com/@stephane.maarek
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TBD:
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* Kafka Producer Metrics
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https://www.datadoghq.com/blog/monitoring-kafka-performance-metrics/
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https://medium.com/@aiiflo/kafka-producer-metrics-monitoring-key-metrics-aa25bafefcea
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https://docs.confluent.io/platform/current/kafka/monitoring.html#global-request-metrics
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batch-size-avg
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theory
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broker (each broker is also a bootstrap server)
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has an integer ID
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contain certain topic partitions, but not all
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after connecting to any broker (called a bootstrap broker) - connects to the entire cluster
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knows all the metadata (which topic, partitions are there at the cluster)
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topics
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is a particular stream of data
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partitions
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is ordered, order guaranteed only within partition
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data is kept only for some limited amount of time (1 week)
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data is immutable
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offsets
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incremental id (infinite)
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replication factory
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3 is usual, 2 - dangerous
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leader
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at any time only ONE broker can be a Leader for a given partition
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only that leader can receive and serve data for a partition
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the other brokers will synchronize data - ISR (in-sync replica)
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send-mode, ACK
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producer can choose to receive ACK for data-writes ()
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acks=0 , no ack, dangerous
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=1 , wait only for Leader to ack, limited data loss
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=all, wait for all replicas, no data lost
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key of the message
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key=null -> round-robin
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all the messages with the same key go to the same partition
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consumers
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read data in order "within each partition"
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consumer-group
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each consumer within a group reads from exclusive partitions
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in case of number of consumer is greater than partitions, some consumers will be inactive
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each group has "generation" and rebalance consumers upon adding/removing consumers in a group
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!!! by using a new fresh consumer group, it is possible to read all the messages "again"
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consumer-offsets
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kafka stores the offsets at which a consumer group hass been reading
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these offsets are committed live in a Kafka topic "__consumer_offsets"
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these imply "delivery semantics" notion
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delivery semantics
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- at most once (offset is committed as soon as the message is received)
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- at least once (offset is committed only after message has been processed)
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processing system need to be idempotent in this case
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- exactly once, can be achieved for Kafka=>(Kafka Workflows) using Stream API
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zookeeper
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in PROD operates with an odd number of zookeeper-servers (3, 5, 7)
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one is Leader, others - Followers
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zk does not store consumer offsets anymore starting from Kafka > v0.10
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/intro-to-apache-kafka
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/apache-kafka-in-five-minutes
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/kafka-theory-overview
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/topics-partitions-and-offsets
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/brokers-and-topics
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/topic-replication
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/producers-and-message-keys
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/consumer-and-consumer-group
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/consumer-offsets-and-delivery-semantics
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/kafka-broker-discovery
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/zookeeper
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/kafka-guarantees
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/macos-download-and-set-up-kafka-in-path
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...
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/kafka-topics-cli
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kafka-topics
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common-stuff:
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--zookeeper <host>:2181
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--list
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list all existing topics
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--create
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--topic <topic-name>
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--partitions 3
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--replication-factor 2 (need to be more than the number of available brokers)
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--describe
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good table of partitions
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--delete
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mark a topic for deletion (does not delete it right away)
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(delete.topic.enable=true)
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/kafka-console-producer-cli
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kafka-console-producer
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common-stuff:
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--broker-list <host>:9192
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--producer-property
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acks=all
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--topic <topic-name>
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line-by-line till Ctrl-C
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Note: new topic is created if needed (LEADER_NOT_AVAILABLE WARN)
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with default num of partitions and repl-factor
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config/server.properties
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num.partitions=1 # default
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/kafka-console-consumer-cli
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kafka-console-consumer
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common-stuff:
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--bootstrap-server <host>:9192
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--topic <topic-name>
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--from-beginning
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!!! by default, this consumer only reads new messages (from the start moment)
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...
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/kafka-consumers-in-groups
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kafka-console-consumer
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...
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--group <consumer-group-name>
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to be part of a consumer group
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/kafka-consumer-groups-cli
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kafka-consumer-groups
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common-stuff:
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--bootstrap-server <host>:9192
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--list
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... console-consumer-<id>
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--describe <group-name>
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... LAG 0 -> meaning console conumer read all the data
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...
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/resetting-offsets
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kafka-consumer-groups
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...
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--reset-offsets
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--dry-run|--execute
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--by-period
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--to-earliest
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... scopes...
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--all-topics
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--topic <topic-name>
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--shift-by <num>
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--describe
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--group <group-name>
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/kafka-tool-ui
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www.kafkatool.com
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#
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# Java stuff
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#
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https://kafka.apache.org/documentation/
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/creating-a-kafka-project
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mvn deps: org.apache.kafka:kafka-clients
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/java-producer
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https://kafka.apache.org/documentation/#producerapi
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import org.apache.kafka.clients.producer.KafkaProducer;
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import org.apache.kafka.clients.producer.ProducerConfig;
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import org.apache.kafka.common.serialization.StringSerializer;
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Properties properties = new Properties();
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// bootstrap.servers
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properties.setProperty(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "...");
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// key.serializer
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properties.setProperty(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
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// value.serializer
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properties.setProperty(ProducerConfig.VALUEKEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
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// <K, V>
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KafkaProducer<String, String> producer = new KafkaProducer<String, String>(properties);
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// key and other stuff can be here as well
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ProducerRecord<String, String> record = new ProducerRecord<String, String>("first-topic", "some-value");
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// this is async !!!
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producer.send(record);
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// to actually send
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producer.flush();
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// flush and close
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producer.close();
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/java-producer-callbacks
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...
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import org.apache.kafka.clients.producer.Callback;
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...
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// set data asynchronously
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producer.send(record, new Callback() {
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public void onCompletion(RecordMetadata recordMetadata, Exception e) {
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// executes every time record is successfuly sent or an exception is thrown
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if (e == null) {
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// the record was successfully sent
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// log recordMetadata.topic(), .partition(), .offset(), .timestamp()
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} else {
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}
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}
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});
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/java-producer-with-keys
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...
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ProducerRecord<String, String> record = new ProducerRecord<String, String>("first-topic", "some-key", some-value");
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...
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// set data asynchronously
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producer.send(record, new Callback() {
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public void onCompletion(RecordMetadata recordMetadata, Exception e) {
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// executes every time record is successfuly sent or an exception is thrown
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if (e == null) {
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// the record was successfully sent
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// log recordMetadata.topic(), .partition(), .offset(), .timestamp()
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} else {
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}
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}
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}).get(); // block the .send() to make it synchronous. Don't do it in PROD...
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// throws ExecutionException, InterruptedException
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/java-consumer
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import org.apache.kafka.clients.producer.ConsumerConfig;
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import org.apache.kafka.common.serialization.StringDeserializer;
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Properties properties = new Properties();
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// bootstrap.servers
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properties.setProperty(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "...");
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// key.deserializer
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properties.setProperty(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
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// value.deserializer
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properties.setProperty(ConsumerConfig.VALUEKEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
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// groupId
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properties.setProperty(ConsumerConfig.GROUP_ID, "my-fourth-app");
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// auto.offset.reset
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// "earliest" is equivalent to "--from-beginning" CLI option
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properties.setProperty(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest|latest|none");
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KafkaConsumer<String, Strring> consumer = new KafkaConsumer<String, String>(properties);
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consumer.subscribe(Collection.singleton("first-topic")); // Arrays.asList("first-topic", "second-topic")
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while(true) {
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// java.time.Duration
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ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(100)); // deprecated
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for (ConsumerRecord<String, String> record : records) {
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// record .key(), .value(), .partition(), .offset()
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}
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}
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/java-consumer-inside-consumer-group
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...
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groupId = "my-fifth-application"
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...
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// !!! because we started 2-nd consumer, the group started rebalancing
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log:
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INFO org.apache.kafka.clients.consumer.internals.AbstractCoordinator - [Consumer clientId=consumer-1, group-id=my-fifth-application]
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Attempt to heartbeat failed since group is rebalancing
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INFO org.apache.kafka.clients.consumer.internals.ConsumerCoordinator - [Consumer clientId=consumer-1, group-id=my-fifth-application]
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Revoking previously assigned partitions [first_topic-0, first_topic-1, first_topic-2]
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INFO org.apache.kafka.clients.consumer.internals.AbstractCoordinator - [Consumer clientId=consumer-1, group-id=my-fifth-application]
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(Re-)joining group
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INFO org.apache.kafka.clients.consumer.internals.AbstractCoordinator - [Consumer clientId=consumer-1, group-id=my-fifth-application]
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Successfully joined group with generation 2
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INFO org.apache.kafka.clients.consumer.internals.ConsumerCoordinator - [Consumer clientId=consumer-1, group-id=my-fifth-application]
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Setting newly assigned partitions [first_topic-0, first_topic-1]
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/java-consumer-with-threads
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// let's get rid of the ugly while(true) loop
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import java.util.concurrent.CountDownLatch;
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...
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public class ConsumerDemoWithThread {
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public static void main(String[] args) {
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new ConsumerDemoWithThread().run();
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}
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private ConsumerDemoWithThread() {
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}
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private void run() {
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Logger logger = LoggerFactory.getLogger(ConsumerDemoWithThread.class);
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...
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groupId = "my-sixth-application"
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CountDownLatch latch = new CountDownLatch(1);
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Runnable myConsumerRunnable = new ConsumerRunnable(..., latch);
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Thread myThread = new Thread(myConsumerRunnable);
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myThread.start();
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Runtime.getRuntime().addShutdownHook(new Thread( () -> {
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logger.info("Caught shutdown hook");
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((ConsumerRunnable) myConsumerRunnable).shutdown();
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try {
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latch.await();
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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logger.info("Application has exited");
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}))
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try {
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latch.await();
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} catch() {
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logger.error("Application is interrupting", e);
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} finally {
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logger.info("Application is closing");
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}
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}
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public class ConsumerThread extends Runnable {
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private static Logger logger = LoggerFactory.getLogger(ConsumerThread.class);
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private CountDownLatch latch;
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private KafkaConsumer<String, String> consumer;
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public ConsumerThread(String bootstrapServers, String groupId, String topic, CountDownLatch latch) {
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this.latch = latch;
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Properties properties = new Properties();
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// bootstrap.servers
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properties.setProperty(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
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// key.deserializer
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properties.setProperty(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
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// value.deserializer
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properties.setProperty(ConsumerConfig.VALUEKEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
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// groupId
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properties.setProperty(ConsumerConfig.GROUP_ID, groupId);
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// auto.offset.reset
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// "earliest" is equivalent to "--from-beginning" CLI option
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properties.setProperty(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest|latest|none");
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consumer = new KafkaConsumer<String, String>(properties);
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}
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@Override
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public void run() {
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try {
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while(true) {
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// java.time.Duration
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ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(100)); // deprecated
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for (ConsumerRecord<String, String> record : records) {
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// record .key(), .value(), .partition(), .offset()
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}
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}
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} catch (WakeupException e) {
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logger.info("received shutdown exception");
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} finally {
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// super-important!
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consumer.close();
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// tell our main thread that we're done with the consumer
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latch.countDown();
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}
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}
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public void shutdown() {
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// a special method to interrupt consumer.poll()
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// it will throw WakeupException
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consumer.wakeup();
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}
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}
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|
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https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/java-consumer-seek-and-assign
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// assign and seek
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import org.apache.kafka.common.TopicPartition;
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...
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remove the groupId property:
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// properties.setProperty(ConsumerConfig.GROUP_ID, groupId);
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and don't subscribe to topic
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// consumer.subscribe(Collection.singleton("first-topic")); // Arrays.asList("first-topic", "second-topic")
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// assign and seek are mostly used to replay data or fetch a specific message
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// assign
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TopicPartition partition = new TopicPartition(topic, 0); // partition 0
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consumer.assign(Arrays.asList(partitionsToReadFrom));
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// seek
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long offsetToReadFrom = 15L;
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consumer.seek(partitionsToReadFrom, offsetToReadFrom); // this consumer should read from these partitions and offsets
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int numberOfMessagesToRead = 5;
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boolean keepOnReading = true;
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int numberOfMessagesReadSoFar = 0;
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while(keepOnReading) {
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// java.time.Duration
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ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(100)); // new in Kafka 2.0
|
|
for (ConsumerRecord<String, String> record : records) {
|
|
numberOfMessagesToRead += 1;
|
|
// record .key(), .value(), .partition(), .offset()
|
|
if (numberOfMessagesReadSoFar >= numberOfMessagesToRead) {
|
|
keepOnReading = false; // to exit while-loop
|
|
break to exit for-loop
|
|
}
|
|
}
|
|
}
|
|
logger.info("Exitin the application");
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/client-bidirectional-compatibility
|
|
// As of kafka 0.10.2 (July 2017) it has bi-directional compatibility
|
|
- an OLDER client (ex 1.1) can talk to a newer broker (2.0)
|
|
- a NEWER client (ex 2.0) can talk to an older broker (1.1)
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/twitter-setup
|
|
https://apps.twitter.com
|
|
https://developer.twitter.com
|
|
for personal use
|
|
...
|
|
keys&tokens -> Consumer API keys (API key, API secret key)
|
|
access token & access token secret
|
|
https://github.com/twitter/hbc
|
|
com.twitter:hbc-core
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/producer-part-1-writing-a-twitter-client
|
|
...
|
|
import java.util.concurrent.BlockingQueue;
|
|
import java.util.concurrent.LinkedBlockingQueue;
|
|
|
|
public class TwitterProducer {
|
|
private static Logger logger = LoggerFactory.getLogger(TwitterProducer.class);
|
|
|
|
public TwitterProducer() {
|
|
}
|
|
|
|
public static void main(String[] args) {
|
|
new TwitterProducer().run();
|
|
}
|
|
|
|
public void run() {
|
|
// create a twitter client
|
|
BlockingQueue<String> msgQueue = new LinkedBlockingQueue<String>(100000);
|
|
Client client = createTwitterClient();
|
|
|
|
// attempt to establish connection
|
|
client.connect();
|
|
|
|
// create a kafka producer
|
|
|
|
// loop to send tweets to kafka
|
|
while (!client.isDone()) {
|
|
try {
|
|
String msg = msgQueue.poll(5, TimeUnit.SECONDS);
|
|
} catch (InterruptedException e) {
|
|
e.printStackTrace();
|
|
client.stop();
|
|
}
|
|
if (msg != null) {
|
|
logger.info(msg);
|
|
}
|
|
}
|
|
logger.info("End of application");
|
|
}
|
|
|
|
String concumerKey = "";
|
|
// ...
|
|
|
|
public Client createTwitterClient(BlockingQueue<String> msgQueue) {
|
|
// ...
|
|
Hosts hosebirdHosts = new HttpHosts(Constants.STREAM_HOST);
|
|
StatusesFilterEndpoint hosebirdEndpoint = new StatusesFilterEndpoint();
|
|
|
|
List<String> terms = Lists.newArrayList("kafka");
|
|
hosebirdEndpoint.trackTerms(terms);
|
|
|
|
Authentication hosebirdAuth = new OAuth1(consumerKey, consumerSecret, token, tokenSecret);
|
|
|
|
ClientBuilder builder = new ClientBuilder()
|
|
.name("...")
|
|
.hosts(hosebirdHosts)
|
|
.authentication(hosebirdAuth)
|
|
.endpoint(hosebirdEndpoint)
|
|
.processor(new StringDelimitedProcessor(msgQueue))
|
|
|
|
Client hosebirdClient = builder.build();
|
|
return hosebirdClient
|
|
}
|
|
}
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/producer-part-2-writing-the-kafka-producer
|
|
...
|
|
public KafkaProducer<String, String> createKafkaProducer() {
|
|
Properties properties = new Properties();
|
|
properties.setProperty(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "...");
|
|
properties.setProperty(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
|
|
properties.setProperty(ProducerConfig.VALUEKEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
|
|
|
|
// <K, V>
|
|
KafkaProducer<String, String> producer = new KafkaProducer<String, String>(properties);
|
|
return producer;
|
|
}
|
|
...
|
|
// create a kafka producer
|
|
KafkaProducer<String, String> producer = createKafkaProducer();
|
|
|
|
// add a shutdown hook
|
|
Runtime.getRuntime().addShutdownHook(new Thread(() -> {
|
|
logger.info("stopping twitter client");
|
|
client.stop();
|
|
logger.info("closing producer");
|
|
producer.stop();
|
|
logger.info("done");
|
|
}));
|
|
|
|
// loop to send tweets to kafka
|
|
// on a different thread, or multiple different threads...
|
|
while (!client.isDone()) {
|
|
String msg = null;
|
|
try {
|
|
msg = msgQueue.poll(5, TimeUnit.SECONDS);
|
|
} catch (InterruptedException e) {
|
|
e.printStackTrace();
|
|
client.stop();
|
|
}
|
|
if (msg != null) {
|
|
logger.info(msg);
|
|
producer.send(new ProducerRecord<>("twitter_tweets", null, msg), new Callback() { // topic, key, value
|
|
@Override
|
|
public void onCompletion(RecordMetadata recordMetadata, Exception e) {
|
|
if (e != null) {
|
|
logger.error(e.getMessage(), e);
|
|
}
|
|
}
|
|
});
|
|
}
|
|
}
|
|
|
|
$ kafka-topics --zookeper 127.0.0.1:2181 --create --topic tweeter_tweets --partitions 6 --replication-factor 1
|
|
... created topic tweeter_tweets
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/producer-configurations-introduction
|
|
note: in the logs
|
|
INFO org.apache.kafka.clients.producer.ProducerConfig - ProducerConfig values:
|
|
acks = 1
|
|
batch.size = 16384
|
|
bootstrap.servers = [127.0.0.1:2181]
|
|
buffer.memory = 33554432
|
|
client.id =
|
|
compression.type = none
|
|
enable.idempotence = false
|
|
interceptor.classes = []
|
|
key.serializer = org.apacke.kafka.common.serialization.StringSerializer
|
|
linger.ms = 0
|
|
max.request.size =
|
|
value.seializer =
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/acks-and-min-insync-replicas
|
|
Producer Acks Deep Dive
|
|
acks = 0 (no acks), useful if it's ok to potentially loose messages, nice for performance
|
|
acks = 1 (leader acknoledgements)
|
|
acks = all (leader + replicas), most guarantee, adds safety and latency
|
|
must be used in conjunction with
|
|
min.insync.replicas - can be set at the broker or topic level (override)
|
|
min.insync.replicas = 2 (at least 2 brokers, incl the leader, must respond)
|
|
Exception: NOT_ENOUGH_REPLICAS
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/retries-and-max-in-flight-requests-per-connection
|
|
Producer Retries
|
|
in case of transient failures, developers are expected to handle exceptions,
|
|
otherwise the data will be lost.
|
|
Example of transient failure:
|
|
* NotEnoughReplicasException
|
|
Thre is a "retries" setting
|
|
* defaults to 0
|
|
* You can increase even to an Integer.MAX_VALUE
|
|
In case of retries, by default there is a chance that messages will be sent out of order
|
|
(if a batch has failed to be sent)
|
|
If you rely on key-based ordering, that can be an issue
|
|
For this, you can set the setting while controls how many produce
|
|
requests can be made in parallell (to any partition):
|
|
max.in.flight.requests.per.connection
|
|
* Defaults: 5
|
|
* set to 1 if you need to ensure ordering (may impact throughput)
|
|
In Kafka >= 1.0.0 there is a better (and simpler one) solution
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/idempotent-producer
|
|
The Producer can introduce duplicate messages in Kafka due to the network errors
|
|
If "ack" from kafka does not go back to producer due to the network errors,
|
|
producer produce "retry" request and kafka commits duplicate
|
|
|
|
In Kafka >= 0.11, you can define a "idempotent producer",
|
|
which introduces "commit id"
|
|
|
|
They (idempotent producers) come with
|
|
* retries = Integer.MAX_VALUE (2^31 - 1)
|
|
* max.in.flight.requests = 1 (kafka >= 0.11 || kafka < 1.1)
|
|
* max.in.flight.requests = 5 (kafka >= 1.1 - higher performance)
|
|
* acks = all
|
|
|
|
just set:
|
|
producerProps.put("enable.idempotence", "true")
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/producer-part-3-safe-producer
|
|
kafka < 0.11
|
|
* acks = all
|
|
* min.insync.replicas = 2 (broker/topic level)
|
|
ensures two brokers in ISR at least have the data after an ack
|
|
* retry = MAX_INT (producer level)
|
|
ensures transient errors are retried indefinitely
|
|
* max.in.flight.requests.per.connection = 1 (producer level)
|
|
|
|
kafka >= 0.11
|
|
* enable.idempotence = true (producer level) + min.insync.replicas = 2 (broker/topic level)
|
|
implies acks = all, retry = MAX_INT, max.in.flight.requests = 5 (default)
|
|
while keeping ordering guarantees and improving performance!
|
|
and also don't get duplicates
|
|
|
|
!!! running idempotence producer impact througput and latency, always test
|
|
...
|
|
properties.setProperty(ProducerConfig.ENABLE_IDEMPOTENCE_CONFIG, "true");
|
|
properties.setProperty(ProducerConfig.ACKS_CONFIG, "all");
|
|
properties.setProperty(ProducerConfig.RETRIES_CONFIG, Integer.toString(Integer.MAX_VALUE);
|
|
properties.setProperty(ProducerConfig.MAX_IN_FLIGHT_REQUESTS_PER_CONNECTION, "5"); // for kafka >= 1.1
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/producer-compression
|
|
compression.type
|
|
* note (default)
|
|
* gzip
|
|
* lz4
|
|
* snappy
|
|
|
|
it is more effective the bigger the batch of message being sent to Kafka
|
|
* benchmark here (https://blog.coudflare.com/squeezing-the-firehose)
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/producer-batching
|
|
...
|
|
by default, kafka tries to send data as soon as possible
|
|
* It will have up to 5 requests in flight,
|
|
meaning up to 5 messages individually sent at the same time
|
|
* After this, if more messages have to be sent while others are in flight,
|
|
Kafka is smart and will start batching them while they wait
|
|
to send them all at once
|
|
This smart batching allows Kafka to increase throughput
|
|
while maintaining very low latency
|
|
Batches have higher compression ratio so better efficiency
|
|
all messages in a batch are sent in one request
|
|
|
|
How to control batching?
|
|
* linger.ms - number of ms, a producer is willing to wait
|
|
before sending a batch out (default 0)
|
|
by introducing some lag (for example linger.ms=5) we increase
|
|
chances of messages being sent togeather in a batch
|
|
* if batch is full (see batch.size) before the end of the linger.ms period,
|
|
it will be sent to Kafka right away
|
|
the default is 16Kb (can increase to 32/64)
|
|
any message bigger will not be batched
|
|
A batch is allocated per partition
|
|
Note: you can monitor the average batch size metric using
|
|
* Kafka Producer Metrics
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/producer-part-4-high-throughput-producer
|
|
* add "snappy" for mainly text-data
|
|
* batch size to 32Kb
|
|
* linger.ms to 20ms
|
|
|
|
properties.setProperty(ProducerConfig.COMPRESSION_TYPE_CONFIG, "snappy");
|
|
properties.setProperty(ProducerConfig.LINGER_MS_CONFIG, "20");
|
|
properties.setProperty(ProducerConfig.BATCH_SIZE_CONFIG, Integer.toString(32*1024));
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/producer-default-partitions-and-key-hashing
|
|
by default, keys are hashed using the
|
|
* murmur2
|
|
|
|
It is possible to override the behavior of the partitioner
|
|
* partitioner.class
|
|
The formula is:
|
|
* targetPartition = Utils.abs(Utils.murmur2(record.key())) % numPartitions;
|
|
|
|
If the producer produces faster than the broker can take,
|
|
the recors will be buffered in memory
|
|
* buffer.memory = 33554432 (32Mb): the size of the send buffer
|
|
|
|
If the buffer is full (32Mb), then the .send() method will start to block
|
|
(won't return right away)
|
|
* Max.block.ms = 60000 (1 min) - the time .send() will block
|
|
untill throwing an exception for couple of reasons
|
|
* the producer has filled up its buffer
|
|
* the broker is not accepting any new data
|
|
* 60 seconds has elapsed
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/refactoring-the-project
|
|
create maven modules:
|
|
* kafka-basics
|
|
* kafka-producer-twitter
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/setting-up-elasticsearch-in-the-cloud
|
|
https://bonsai.io/
|
|
creds, interactiv console
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/elasticsearch-101
|
|
https://www.elastic.co/guide/en/elasticsearch/reference/current/_cluster_health.html
|
|
/_cat/health?v
|
|
/_cat/nodes?v
|
|
/_cat/indices?v
|
|
PUT
|
|
/twitter
|
|
{}
|
|
/twitter/tweets/1
|
|
{
|
|
"course": "Kafka for beg...",
|
|
"instructor": "Stephane Maarek",
|
|
"module": "ElasticSearch"
|
|
}
|
|
GET
|
|
/twitter/tweets/1
|
|
{
|
|
"_index": "twitter",
|
|
"_type": "tweets",
|
|
"_id": 1,
|
|
"_version": 2,
|
|
"found": true,
|
|
"_source": {
|
|
"course": "Kafka for beg...",
|
|
"instructor": "Stephane Maarek",
|
|
"module": "ElasticSearch"
|
|
}
|
|
}
|
|
DELETE
|
|
/twitter
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/consumer-part-1-set-up-project
|
|
https://www.elastic.co/guide/en/elasticsearch/client/java-rest/current/java-rest-high-getting-started-maven.html
|
|
dep: org.elasticsearch.client:elasticsearch-rest-high-level-client:6.4.0
|
|
|
|
public class ElasticSearchConsumer {
|
|
public static RestHighLevelClient createClient() {
|
|
// https://<username>:<password>@<hostname>
|
|
String hostname = "";
|
|
String username = "";
|
|
String password = "";
|
|
// !!! not for the case of local ES
|
|
final CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
|
|
credentialsProvider.setCredentials(AuthScope.ANY,
|
|
new UsernamePasswordCredentials(username, password));
|
|
RestClientBuilder builder = RestClient.builder(
|
|
new HttpHost(hostname, 443, "https"))
|
|
.setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
|
|
@Override
|
|
public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpClientBuilder) {
|
|
return httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider);
|
|
}
|
|
});
|
|
|
|
RestHighLevelClient client = new RestHighLevelClient(builder);
|
|
return client;
|
|
}
|
|
|
|
public static void main(String[] args) throws IOException {
|
|
RestHighLevelClient client = createClient();
|
|
String jsonString = "{\"foo\": \"bar\"}"
|
|
IndexRequest indexRequest = new IndexRequest("twitter", "tweets")
|
|
.source(jsonString, XContentType.JSON);
|
|
// IOException
|
|
IndexResponse indexResponse = client.index(indexRequest, RequestOptions.DEFAULT);
|
|
String id = indexResponse.getId();
|
|
logger.info(id);
|
|
client.close();
|
|
}
|
|
}
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/consumer-part-2-write-the-consumer-and-send-to-elasticsearch
|
|
...
|
|
// String topic = "twitter_tweets";
|
|
public static KafkaConsumer<String, String> createConsumer(String topic) {
|
|
...
|
|
String groupId = "kafka-demo-elasticsearch";
|
|
...
|
|
properties.setProperty(ConsumerConfig.GROUP_ID, groupId);
|
|
...
|
|
// "earliest" is equivalent to "--from-beginning" CLI option
|
|
properties.setProperty(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest|latest|none");
|
|
...
|
|
KafkaConsumer<String, String> consumer = new KafkaConsumer<String, String>(properties);
|
|
consumer.subscribe(Arrays.asList(topic));
|
|
return consumer;
|
|
}
|
|
...
|
|
public static void main(String[] args) {
|
|
...
|
|
while(true) {
|
|
// java.time.Duration
|
|
ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(100));
|
|
for (ConsumerRecord<String, String> record : records) {
|
|
// record .key(), .value(), .partition(), .offset()
|
|
|
|
String jsonString = record.value();
|
|
|
|
IndexRequest indexRequest = new IndexRequest(
|
|
"twitter", // indexer
|
|
"tweets" // type
|
|
).source(jsonString, XContentType.JSON);
|
|
|
|
IndexResponse indexResponse = client.index(indexRequest, RequestOptions.DEFAULT);
|
|
String id = indexResponse.getId();
|
|
logger.info(id);
|
|
|
|
Thread.sleep(1000); // just for demo
|
|
}
|
|
}
|
|
// client.close();
|
|
}
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/consumer-part-3-delivery-semantics
|
|
// making it idempotent by tracking id
|
|
...
|
|
IndexRequest indexRequest = new IndexRequest(
|
|
"twitter", // indexer
|
|
"tweets", // type
|
|
id // !!!
|
|
)...
|
|
...
|
|
// 2 strategies
|
|
//
|
|
// 1. kafka generic id
|
|
// String id = record.topic() + "_" + record.partition() + "_" + record.offset();
|
|
//
|
|
// 2. twitter specific id
|
|
String id = extractIdFromTweet(record.value());
|
|
|
|
IndexRequest indexRequest = new IndexRequest(
|
|
"twitter", // indexer
|
|
"tweets", // type
|
|
id // this is to make consumer idempotent
|
|
).source(jsonString, XContentType.JSON);
|
|
...
|
|
// google gson
|
|
private static JsonParser jsonParser = new JsonParser();
|
|
|
|
private static String extractIdFromTweet(String tweetJson) {
|
|
return jsonParser.parse(tweetJson)
|
|
.getAsJsonObject()
|
|
.get("id_str")
|
|
.getAsString();
|
|
}
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/delivery-semantics-for-consumers
|
|
At most once
|
|
offsets are committed as soon as the message batch is received.
|
|
If the process goes wrong, the message will be lost
|
|
(it won't be read again)
|
|
|
|
At least once
|
|
offsets are committed after the message is processed
|
|
if the processing goes wrong, the message will be read again
|
|
This can result in duplicate processing of messages.
|
|
Make sure your processing is idempotent
|
|
|
|
Exactly once
|
|
only for Kafka => Kafka workflows
|
|
using Kafka Streams API
|
|
for Kafka => Sink workflows, use an idempotent consumer
|
|
|
|
https://www.linkedin.com/learning/learn-apache-kafka-for-beginners/delivery-semantics-for-consumers
|
|
1:00
|
|
...
|
|
properties.setProperty(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest|latest|none");
|