CCDAK Exam Dumps - Confluent Certified Developer for Apache Kafka Certification Examination

Low I/O thread activity with blocked throughput often indicates thatproducer callbacks are consuming too much time, causing the sender thread to block while waiting for onCompletion() to finish.

FromKafka Producer Performance Guide:

“Expensive logic in callbacks (e.g., I/O or complex computation) can block the sender thread, reducing throughput.”

Compression (A) may slightly impact CPU but not I/O thread usage.

Large batches (B) improve throughput if managed correctly.

A Layer 2 network issue (C) would lead to packet loss, not specifically low callback metrics.

Each of these settings plays a key role inKafka Connect offset management:

offset.flush.interval.ms=60000 → Offset commits happen every 60 seconds.

offset.flush.timeout.ms=500 → The flush operation times out if it takes more than 500 ms.

offset.storage.topic=connect-offsets → This is the internal topic for storing source offsets.

offset.storage.replication.factor=-1 → This uses thebroker's default replication factor(commonly set via default.replication.factor).

FromKafka Connect Docs:

“If offset.storage.replication.factor=-1, the value will be determined by the broker's default replication factor.”