Handling Cancellation Tokens with Parallel.ForEach in C# 10 - Unexpected Behavior on Task Cancellation
I'm deploying to production and Quick question that's been bugging me - I'm using `Parallel.ForEach` in a C# 10 application to process a collection of items concurrently. I've integrated cancellation support using `CancellationToken`, but I'm encountering unexpected behavior. When I cancel the operation, some of the tasks seem to continue executing instead of gracefully stopping. I expected that once cancellation is requested, the loop would cease processing additional items. Here's a simplified version of the code I'm using: ```csharp public void ProcessItems(IEnumerable<MyItem> items, CancellationToken cancellationToken) { Parallel.ForEach(items, new ParallelOptions { CancellationToken = cancellationToken }, (item) => { if (cancellationToken.IsCancellationRequested) { // Log cancellation request and return to stop further processing. Console.WriteLine("Cancellation requested"); return; } // Simulate some work DoWork(item); }); } ``` The `DoWork` method simulates a time-consuming task: ```csharp private void DoWork(MyItem item) { Thread.Sleep(1000); // Simulating work } ``` When I invoke this method and preemptively cancel it via a `CancellationTokenSource`, I see the cancellation message, but several tasks still complete their execution despite the cancellation. I expected that the `IsCancellationRequested` check would prevent this. I've tried moving the cancellation check to the beginning of the `DoWork` method, but it doesn't seem to have an effect. I'm not using `async/await` in this case since I'm sticking with the synchronous model here. Is there a better way to handle cancellation in `Parallel.ForEach` so that it respects the cancellation request properly? Any advice would be appreciated! For context: I'm using C# on macOS. Cheers for any assistance!