Given a Kafka consumer with enable.auto.commit=false and manual commit after processing, what happens if the consumer crashes before commit?

medium📝 Predict Output Q4 of Q15

Kafka - Message Delivery Semantics

Given a Kafka consumer with enable.auto.commit=false and manual commit after processing, what happens if the consumer crashes before commit?

AMessages will be reprocessed after restart, causing duplicates

BMessages are lost and never reprocessed

CConsumer automatically commits offsets before crash

DMessages are skipped and not delivered again

Step-by-Step Solution

Solution:

Step 1: Understand manual commit behavior
With auto commit disabled, offsets are only saved when committed manually.
Step 2: Analyze crash before commit
If crash happens before commit, offsets are not saved, so messages reprocessed on restart.
Final Answer:
Messages will be reprocessed after restart, causing duplicates -> Option A
Quick Check:
Manual commit + crash before commit = duplicates [OK]

Quick Trick: Manual commit requires commit before crash to avoid duplicates [OK]

Common Mistakes:

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