What are common failure modes of Consumer Groups and Rebalance?

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Quick interview answer

Common failures around Consumer Groups and Rebalance: blocking the hot path, ignoring backpressure, and weak timeout/retry design. Long processing without pause; committing before side effects complete.

Detailed answer

Failure modes for Consumer Groups and Rebalance: Known pitfalls: Long processing without pause; committing before side effects complete. • Missing timeouts / unbounded retries • No backpressure when downstream slows • Assuming ordering/guarantees the runtime does not provide How seniors prevent them: Idempotent consumers; static membership; cooperative sticky assignor. Parent context: Use Consumer Groups and Rebalance as the core idea. Example shape: 6 partitions, 3 consumers → each gets 2 partitions; add 4th consumer triggers rebalance..

Full explanation

Name concrete failure modes and the mitigation for each — that scores higher than a vague “it can fail.” Each partition consumed by one consumer in group. Rebalance on member join/leave — can cause duplicate processing if offsets not committed carefully.

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Parent context — Consumer Groups and Rebalance

Use Consumer Groups and Rebalance as the core idea. Example shape: 6 partitions, 3 consumers → each gets 2 partitions; add 4th consumer triggers rebalance..

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