SNS - OS intensive
But intensive in very specific ways:
- OS services used are for data movement (local, SAN, and WAN), not computation
- 1000s of parallel tasks (much state management)
- e.g. HotBot crawler: ᡂ,000 connections across 11 machines
- Thread subsystem is heavily taxed
- high network latencies imply order of magnitude more threads than usual
- many locks, thread context switches