Workflow never completes when waiting on multiple activities unless ToList is used about dotnet-sdk HOT 4 CLOSED

@stuartleeks Do you have a repro project that you can share? I threw together a project but do not see that behavior; the workflow completes as expected once all the activities complete, whether .ToList() is used or not.

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@philliphoff - I've created a stripped back version of the project where I hit this and pushed it here: https://github.com/stuartleeks/dapr-wf-csharp-1211

Hopefully it's easy to set up/run, but let me kjnow if you have any questions

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Ok, so found the problem:

	await Task.WhenAll(activityTasks);

	var result = activityTasks.Select(t=>t.Result).ToArray();

...should instead be:

	var result = await Task.WhenAll(activityTasks);

In the original, activityTasks is a LINQ-based lazily-evaluated IEnumerable<Task>. It will first be evaluated by the Task.WhenAll() which causes the activities to be spawned and then awaited. Once that's done, it gets to the activityTasks.Select(t=>t.Result).ToArray(). This causes a second evaluation of the enumerable which spawns the activities again, but then tries to synchronously wait for each to finish (due to the use of Result), which is where I think the problem arises.

Task.WhenAll() returns the results of each awaited Task so that they can be used without reevaluating the original enumerable.

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Ah, good spot 🤦

Thanks!

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