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

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

From Kafka 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.

Kafka Connect can run in standalone mode or distributed mode. For simple tasks like reading logs from a file on a single host, standalone mode is recommended.

From Kafka Connect User Guide:

“Standalone mode is useful when running connectors on a single machine (e.g., for development or simple deployments like log collection from a local file).”

Distributed mode is preferred for scalability and fault tolerance but overkill for this use case.

max.poll.interval.ms defines the maximum delay between invocations of poll() before the consumer is considered failed. It essentially gives consumers more time to process records before needing to poll again.

From Kafka Consumer Configuration Reference:

“max.poll.interval.ms: The maximum delay between invocations of poll() when using consumer group management. If poll() is not called before expiration, the consumer is considered failed.”

session.timeout.ms and heartbeat.interval.ms relate to group coordination and heartbeats.

fetch.max.wait.ms affects how long the broker waits to accumulate data before sending a fetch response.