[Solved] Identify the bug in this Kafka consumer code that aims for at-least-once delivery: consumer.subscribe(['topic']) for message in consumer: consumer.commit() process(message) | Kafka

Kafka - Message Delivery Semantics

Identify the bug in this Kafka consumer code that aims for at-least-once delivery:

consumer.subscribe(['topic'])
for message in consumer:
    consumer.commit()
    process(message)

AUsing subscribe instead of assign causes duplicates

BCommitting offset before processing causes message loss on failure

CNot committing offsets causes infinite reprocessing

Dprocess() function is missing a return statement

Step-by-Step Solution

Solution:

Step 1: Check commit position relative to processing
Offsets are committed before processing, so if processing fails, message is lost.
Step 2: Understand at-least-once requirement
To guarantee at-least-once, commit must happen after successful processing to avoid loss.
Final Answer:
Committing offset before processing causes message loss on failure -> Option B
Quick Check:
Commit after processing to avoid loss [OK]

Quick Trick: Commit offsets only after processing completes [OK]

Common Mistakes:

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