**Good Signs**: Even task duration (no skew). Low GC time. No spill. High executor compute time vs. total. Input bytes processed. No task failures. **Bad Signs**: Skewed task duration (one 10x longer). High GC. Spill (memory/disk). Low compute ratio. Task failures. Growing...
This easy-level Spark/Big Data question appears frequently in data engineering interviews at companies like Delivery Hero. While less common, it tests deeper understanding that distinguishes strong candidates. Mastering the underlying concepts (spark) will help you answer variations of this question confidently.
Start by clearly defining the core concept being asked about. Interviewers want to see that you understand the fundamentals before diving into implementation details. Structure your answer with a definition, then explain the practical application with a concise example.
Good Signs: Even task duration (no skew). Low GC time. No spill. High executor compute time vs. total. Input bytes processed. No task failures.
Bad Signs: Skewed task duration (one 10x longer). High GC. Spill (memory/disk). Low compute ratio. Task failures. Growing backlog.
Spark UI Metrics: Stage duration, shuffle read/write, GC time, spill. Task duration histogram. DAG.
SLA Metrics: End-to-end duration, success rate. Alert on p99 > baseline.
Scalability Trade-offs: Too many metrics = noise. Focus on duration, skew, spill, failures.
Cost Implications: Good metrics = fast triage. Prevent recurring failures.
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Analyze My Answer — FreeAccording to DataEngPrep.tech, this is one of the most frequently asked Spark/Big Data interview questions, reported at 1 company. DataEngPrep.tech maintains a curated database of 1,863+ real data engineering interview questions across 7 categories, verified by industry professionals.