Process Scheduler Simulation
What this preview is
Process Scheduler Simulation is a hard quant coding problem on operating systems in Python, asked at Quant.
- Difficulty
- Hard
- Topic
- Operating Systems
- Discipline
- Quant development
- Language
- Python
Building a preemptive scheduler with aging in Python
This is a hard coding problem that tests your ability to simulate a realistic operating-system scheduler. It combines discrete-event thinking, priority queue management, and careful state tracking — all under tight specification. Firms like DE Shaw care deeply about scheduler behaviour because jitter in thread scheduling directly impacts latency-sensitive trading systems.
The core challenge is managing preemption correctly. You must detect when a newly arrived or aged process has better priority than the currently running one, interrupt it mid-burst, and swap in the new process. At the same time, you need to track when aging occurs (at fixed time boundaries), apply it only to waiting processes, and re-evaluate scheduling immediately after. Edge cases include tie-breaking by arrival time and PID, handling processes that arrive simultaneously, and ensuring that priority never goes below zero.
- Discrete-event simulation and timeline management
- Priority-based scheduling with preemption logic
- State transitions (ready, running, waiting) and process lifecycle
- Correct application of aging to waiting processes only
- Tie-breaking rules and deterministic ordering