Apache Kafka Kafka Architecture & Internals 3

Question 1

What is the purpose of Kafka's `__consumer_offsets` topic compaction?

Accepted Answer

To retain only the latest committed offset per consumer group and partition, keeping the topic size manageable

Answer

Log compaction on __consumer_offsets ensures that only the most recent offset commit per (group, topic, partition) key is retained, preventing unbounded growth.

Question 2

What does `isolation.level=read_committed` do for a Kafka consumer?

Accepted Answer

Causes the consumer to skip transactional messages that have not yet been committed, avoiding dirty reads

Answer

read_committed isolation level ensures consumers only see messages from committed transactions, hiding in-flight or aborted transactional records.

Question 3

What is a Kafka 'broker rack' configuration used for?

Accepted Answer

Assigns a broker to a rack/availability zone so partition replicas can be spread across failure domains

Answer

The broker.rack setting tells Kafka to spread partition replicas across different racks or AZs so that a single rack failure won't take down all replicas of a partition.

Question 4

What is a 'fetch session' in the Kafka broker's fetch protocol?

Accepted Answer

An incremental fetch optimization where the broker caches partition state between fetches, reducing repeated metadata overhead

Answer

Fetch sessions (incremental fetch) allow the broker and consumer to maintain a session so that the fetch request only needs to include changed partitions, reducing network overhead.

Question 5

What is the significance of `max.in.flight.requests.per.connection` in a Kafka producer?

Accepted Answer

Controls how many unacknowledged requests can be in flight simultaneously; setting it to 1 preserves ordering under retries

Answer

If retries > 0 and max.in.flight.requests.per.connection > 1, a retry can cause message reordering; setting it to 1 guarantees order at the cost of throughput.

Apache Kafka Practice Test

Apache Kafka Practice Test

Apache Kafka Kafka Architecture & Internals 3