1.
In JAVA, process of deallocating memory is handled automatically by the garbage collector.
Kafka brokers as JVMs rely heavily on the garbage collector for overall performance tuning.
2.
When a consumer wants to join a group, it sends a JoinGroup request to the group coordinator.
The first consumer to join the group becomes the group leader.
The leader receives a list of all consumers in the group from group coordinator and is responsible for assigning a subset of partitions to each consumer.
3.
In most cases, Kafka can run optimally with 6GB of RAM for heap size.
4.
Only the broker.id property needs to be unique and permanent for each node in the cluster.
If you run multiple brokers on the same machine you should definitely override the port and log directory as well.
because you want to keep the brokers from all trying to register on the same port or overwrite each other data.
5.
Kafka cluster에 처음 연결 시, bootstrap-server 설정에 , 로 구분된 호스트:포트 쌍을 여러개 주었을 때의 이점은 무엇인가?
Since these servers are just used for the initial connection to discover the full cluster membership.
this list does not have to contain the full set of servers.
you may want more than one, though, in case a server si down
6.
By default, the consumer is configured to auto-commit offsets.
Using auto-commit gives you at least once delivery.
In order to know where to pick up the work, the consumer will read the latest committed offset of each partition and continue from there.
By setting auto.commit.offset = false, offsets will only be committed when the application explicitly chooses to do so.
The simplest and most reliable of the commit APIs is commitSync().
7.
The group coordinator is nothing but one of the broker which receives heartbeats from all consumers of a consumer group.
Every consumer group has exactly one group coordinator.
If a consumer stops sending heartbeats, the coordinator will trigger a rebalance.
그룹 코디네이터는 리더 브로커일 필요는 없다.
When a consumer wants to join a consumer group, it sends a JoinGroup request to the group coordinator.
8.
The major APIs in Kafka
- Producer API
- Consumer API
- Streams API
- Connect API
- Admin API
