CODEWITHSUNDEEP
c#async-awaittask-parallel-library
amateur
amateur

Reputation: 44625

RunSynchronously may not be called on task that was already started

I am having an issue with a c# class I created for unit testing my application, in particular the issue is around a System.Threading.Tasks.Task object.

I have a list of such objects and on them I want to execute each synchronously.

I call the following:

myTask.RunSynchronously();

When I do such, I am always getting the following error and I dont know why are how I can fix it.

System.InvalidOperationException: RunSynchronously may not be called on task that was already started.

Anyone got any ideas?

Upvotes: 41

Views: 35686

Answers (3)

Dawid Wekwejt
Dawid Wekwejt

Reputation: 543

You tried to run again a Task or it is in state executed or canceled. Check a part of documentation below:

Task.RunSynchronously Method

Runs the Task synchronously on the current TaskScheduler.

InvalidOperationException The Task is not in a valid state to be started. It may have already been started, > executed, or canceled, or it may have been created in a manner that doesn't support direct scheduling.

Source: Docs .NET Task.RunSynchronously Method

Upvotes: 1

Tejs
Tejs

Reputation: 41246

The problem is that you started the task when you call TaskFactory.StartNew - I mean, it's even in the name of the method that you are starting the task. StartNew creates the task, then calls Start on your behalf. =D

If you want, you can either Wait on the task, like @Peter Ritchie said, or you can create the task manually like so:

var task = new Task(() => { ... });
task.RunSynchronously();

Upvotes: 49

Peter Ritchie
Peter Ritchie

Reputation: 35870

It's already started, just use myTask.Wait()

Upvotes: 45

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