ASP.NET Core Interview Question #167

How can periodic background work be implemented safely?

Logging, Error Handling & Background Services Mid-Level Intermediate

Quick Interview Answer

Periodic work can be implemented with a BackgroundService and PeriodicTimer. Each iteration should observe the cancellation token, handle failures deliberately, and avoid overlapping executions unless concurrency is intentional.

Detailed Explanation

If a job requires durable scheduling, retries across process restarts, distributed coordination, or exactly-once-like business guarantees, an in-process timer alone may be insufficient. A persistent job scheduler or queue can be more appropriate.

The worker should also avoid holding scoped services between iterations.

Code Example

public class ReportWorker : BackgroundService
{
    protected override async Task ExecuteAsync(
        CancellationToken stoppingToken)
    {
        using var timer = new PeriodicTimer(
            TimeSpan.FromMinutes(10));

        while (await timer.WaitForNextTickAsync(stoppingToken))
        {
            await GenerateReportsAsync(stoppingToken);
        }
    }
}