BeginnerScenario
5 min
Overlapping Cron Jobs Causing Backlog
SchedulingOperationsPerformance
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Interview Question
Nightly maintenance jobs overlap and create resource contention and backlog. Explain your triage and prevention.
Key Points to Cover
- Map job runtimes and overlaps with observability
- Enforce concurrency locks and timeouts
- Stagger schedules or convert to queue-driven workers
- Right-size resources and add alerts on duration/SLA
Evaluation Rubric
Maps schedule and overlap clearly30% weight
Applies locking/timeouts30% weight
Reschedules or re-architects jobs20% weight
Adds duration/SLA monitoring20% weight
Hints
- 💡Consider leader election for distributed cron.
Common Pitfalls to Avoid
- ⚠️Failing to thoroughly investigate the root cause of contention and just applying generic fixes.
- ⚠️Implementing locks without considering potential deadlocks or the impact on job dependencies.
- ⚠️Over-optimizing by staggering jobs too aggressively, leading to new, less obvious conflicts.
- ⚠️Not involving the teams responsible for the jobs in the scheduling discussions, leading to resistance or unworkable solutions.
- ⚠️Neglecting to document the scheduling changes and their rationale, making future troubleshooting difficult.
Potential Follow-up Questions
- ❓How to ensure exactly-once processing?
- ❓What about retries and idempotency?
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