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Production situations to diagnose out loud: latency spikes, memory growth, cascading failures, bad deploys.
6 questions in Backend Engineering.
Assess the candidate's understanding of advanced priority inversion scenarios in RTOS environments, focusing on chained resources, priority inheritance protocols, and interrupt synchronisation.
Lag is the integral of arrival rate minus service rate, so establish which of the two moved and whether the consumer is slow or stalled. Check lag per partition before per group, rule out a rebalance loop, and remember that adding consumers beyond the partition count does nothing.
Analyse approaches to mitigating packet loss in a fast-paced UDP environment, focusing on forward error correction and redundant data.
A flat p50 rules out a uniform slowdown, so the tail belongs either to a subset of requests or to a queueing effect. Partition the latency histogram by instance, endpoint and tenant before naming a cause, then confirm with traces, GC logs and pool-wait metrics.
Evaluate the candidate's proficiency in implementing and optimising digital signal processing algorithms on hardware, focusing on FIR/IIR trade-offs, fixed-point arithmetic, and instruction-level parallelism.
The database recovered; your clients did not. Sockets to the old primary hang rather than fail, a cached DNS answer keeps pointing at it, the promoted node refuses writes while it finishes, and then the whole fleet reconnects at once. Attribute the ten minutes to those stages before tuning anything.