How do I approach Software Engineering Fundamentals interview questions?

Software Engineering Fundamentals questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master software engineering fundamentals interviews.

What difficulty level is this interview question?

This is a hard difficulty Software Engineering Fundamentals question, commonly asked during Onsite rounds at Nuro.

What role is this question designed for?

This question is commonly asked for Software Engineer candidates at Nuro during technical interviews.

Implement a thread-safe periodic job scheduler

Quick Overview

This question evaluates a candidate's ability to design thread-safe, timer-driven systems, covering synchronization primitives, concurrency control for schedule/cancel APIs, timing assumptions such as a monotonic clock, and handling task overruns in periodic execution.

Problem: Periodic Job Scheduler (Concurrency)

Implement a small in-process job scheduler that can run periodic tasks (functions/callbacks) at a target frequency.

Requirements

You must support scheduling tasks specified as a function/callback.
Each task is periodic , e.g. 50 Hz (50 times per second). You must convert frequency to a period (time interval).
Expose two thread-safe APIs:
- schedule(taskFn, frequencyHz) -> jobId
- cancel(jobId) -> void
The implementation must be runnable (not just a dry run):
- There is at least one dedicated worker thread responsible for executing the tasks.
- Another thread may call schedule() and cancel() concurrently while the worker is running.

Behavioral expectations / assumptions (state clearly in your implementation)

Use a monotonic clock for timing.
Multiple jobs may be scheduled at once.
If a job is cancelled, it should not run again after cancellation takes effect.
Define what happens if a task execution takes longer than its period (e.g., skip missed ticks vs. run immediately to “catch up”).

What to provide

The scheduler data structures and synchronization strategy.
The worker thread loop logic (sleep/wake strategy).
How cancellation is handled safely under concurrency.

Quick Overview

Problem: Periodic Job Scheduler (Concurrency)

Implement a small in-process job scheduler that can run periodic tasks (functions/callbacks) at a target frequency.

Requirements

You must support scheduling tasks specified as a function/callback.

Each task is periodic , e.g. 50 Hz (50 times per second). You must convert frequency to a period (time interval).

Expose two thread-safe APIs:

schedule(taskFn, frequencyHz) -> jobId
cancel(jobId) -> void

The implementation must be runnable (not just a dry run):

There is at least one dedicated worker thread responsible for executing the tasks.
Another thread may call schedule() and cancel() concurrently while the worker is running.

Behavioral expectations / assumptions (state clearly in your implementation)

Use a monotonic clock for timing.

Multiple jobs may be scheduled at once.

If a job is cancelled, it should not run again after cancellation takes effect.

Define what happens if a task execution takes longer than its period (e.g., skip missed ticks vs. run immediately to “catch up”).

What to provide

The scheduler data structures and synchronization strategy.

The worker thread loop logic (sleep/wake strategy).

How cancellation is handled safely under concurrency.

Implement a thread-safe periodic job scheduler

Quick Overview

Problem: Periodic Job Scheduler (Concurrency)

Requirements

Behavioral expectations / assumptions (state clearly in your implementation)

What to provide

Solution

Comments (0)

Implement a thread-safe periodic job scheduler

Quick Overview

Problem: Periodic Job Scheduler (Concurrency)

Requirements

Behavioral expectations / assumptions (state clearly in your implementation)

What to provide

Solution

Comments (0)