How can you gracefully make a Kafka consumer to stop immediately polling data from Kafka and gracefully shut down a consumer application?

Question

Options

• ACall consumer.wakeUp() and catch a WakeUpException
• BCall consumer.poll() in another thread
• CKill the consumer thread

• A
  88% (21)
• B
  4% (1)
• C
  8% (2)

Explanation

Calling consumer.wakeup() is the only thread-safe method on a Kafka consumer, designed specifically to interrupt a blocking consumer.poll() call from another thread - it causes the poll to throw a WakeupException, which you catch to exit the poll loop cleanly and then call consumer.close() before the application exits.

Option B is wrong because consumer.poll() is not thread-safe; the Kafka consumer is single-threaded by design, so calling it from another thread causes unpredictable behavior. Option C is wrong because killing the thread abruptly prevents proper cleanup - the consumer won't commit offsets, close connections, or notify the broker, which can cause rebalance delays and duplicate message processing in other consumers.

Memory tip: Think of wakeup() as a "polite alarm clock" - it interrupts the sleeping poll and gives the consumer time to brush its teeth (commit offsets, close gracefully) before leaving the house.

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