Efficient Parallel Processing in .NET: Using Parallel.ForEach, IServiceScopeFactory, and ConcurrentBag

Parallel processing in .NET can significantly improve performance when dealing with large collections. However, when working with scoped dependencies and thread-safe collections, managing them properly is crucial. This blog explores how to use Parallel.ForEach, IServiceScopeFactory, and ConcurrentBag efficiently.

Why Use Parallel.ForEach?
Parallel.ForEach executes iterations in parallel, utilizing multiple CPU cores to improve performance. However, it does not automatically handle scoped dependencies from IServiceScopeFactory, which is essential when working with services like DbContext in ASP.NET Core.

Why IServiceScopeFactory?
Since DbContext and other scoped services should not be shared across multiple threads, using IServiceScopeFactory ensures each thread gets its own service scope.

Why ConcurrentBag?
When dealing with concurrent operations, ConcurrentBag is a thread-safe collection that allows multiple threads to add or retrieve items without conflicts.


Example:

Code Snippet

public class ParallelProcessingService { private readonly IServiceScopeFactory _scopeFactory; public ParallelProcessingService(IServiceScopeFactory scopeFactory) { _scopeFactory = scopeFactory; } public async Task ProcessDataAsync(List<int> dataList) { var results = new ConcurrentBag<string>(); await Task.Run(() => { Parallel.ForEach(dataList, data => { using var scope = _scopeFactory.CreateScope(); var myService = scope.ServiceProvider.GetRequiredService<IMyService>(); // Simulated processing string result = myService.ProcessData(data); results.Add(result); }); }); Console.WriteLine($"Processed {results.Count} items."); } }

Key Takeaways
- Use Parallel.ForEach for performance gains when processing large collections.
- Utilize IServiceScopeFactory to create scoped services inside parallel loops.
- Store results in ConcurrentBag to ensure thread safety when collecting data.
This approach ensures efficient parallel execution while maintaining the integrity of scoped services in .NET. 🚀