Reviewed by Aditya Kumar · Last reviewed 2026-03-24
Virtual memory: Each process gets large address space; OS maps pages to physical frames; demand paging; swap when RAM full. WHY: Isolation; working set > RAM. For DE: Excessive swap (si/so in vmstat) kills performance. SCALABILITY: Size Spark executors to avoid swap....
Virtual memory: Each process gets large address space; OS maps pages to physical frames; demand paging; swap when RAM full. WHY: Isolation; working set > RAM. For DE: Excessive swap (si/so in vmstat) kills performance. SCALABILITY: Size Spark executors to avoid swap. COST: Swap is 1000x slower than RAM; tune JVM heap to leave OS headroom.
Red Flag: Ignoring swap. Pro-Move: 'We monitor si/so; Spark executors sized at 80% of node memory; no swap in 2 years on prod.'
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