Reviewed by Aditya Kumar Β· Last reviewed 2026-03-25
**Why it matters**: At scale, design choices directly impact reliability, latency, and cost. Wrong decisions compound across jobs and teams. Spark memory: Executor = JVM heap. Split: Execution (shuffle, joins) and Storage (cache). `spark.memory.fraction` (0.6) shared; storage...
Why it matters: At scale, design choices directly impact reliability, latency, and cost. Wrong decisions compound across jobs and teams.
Spark memory: Executor = JVM heap. Split: Execution (shuffle, joins) and Storage (cache). spark.memory.fraction (0.6) shared; storage gets spark.memory.storageFraction as reserved. Shuffle uses execution memory. Off-heap for large data. Best practice: Size executor for workload; monitor spill; tune fractions.
Scalability trade-offs: Partition/parallelism limits; single points of failure; horizontal vs vertical scaling. Cost implications: Sizing, spot vs reserved, optimization ROI.
Red Flag: Ignoring spill. Pro-Move: 'memory.fraction; storage; monitor.'
According to DataEngPrep.tech, this is one of the most frequently asked Spark/Big Data interview questions, reported at 1 company. DataEngPrep.tech maintains an editor-reviewed database of 1,863 data engineering interview questions across 7 categories.