How do you run continuous background tasks with BackgroundService, and what are the risks of injecting Scoped services into it?

Short answer

Inherit from BackgroundService and write the logic in ExecuteAsync(); Scoped services cannot be injected directly because the service is a Singleton, so create a scope manually with IServiceScopeFactory.

Explanation

BackgroundService is the standard way to run long-lived tasks, such as reading a queue or processing work on a schedule. Because a BackgroundService is a Singleton for the application's lifetime, injecting DbContext (which is Scoped) into its constructor throws InvalidOperationException. Instead, inject IServiceScopeFactory and create a scope with using (var scope = _scopeFactory.CreateScope()) inside each cycle.

Code example

public class QueueConsumer(IServiceScopeFactory scopeFactory) : BackgroundService {
    protected override async Task ExecuteAsync(CancellationToken stoppingToken) {
        while (!stoppingToken.IsCancellationRequested) {
            using var scope = scopeFactory.CreateScope();
            var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();
            await db.ProcessPendingOrdersAsync(stoppingToken);
            await Task.Delay(5000, stoppingToken);
        }
    }
}

Common mistakes

• Ignoring the CancellationToken stoppingToken, preventing the application from shutting down gracefully when it receives a stop signal.

Follow-up questions

• How do IOptions, IOptionsSnapshot, and IOptionsMonitor differ in the Options Pattern?

Sources

• Microsoft Learn — Background tasks with hosted services in ASP.NET Core