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c#wpfasynchronoustask
Alexandre Severino
Alexandre Severino

Reputation: 1613

Understanding Threads and Synchronization with .NET and WPF

I've been programming in C++ for years and then moved to .NET. Everything much easier to understand so far, but I still struggle with synchronization things (in theory).

I remember seeing here on Stackoverflow that running a Task won't actually create a new thread! That got me really confused.

How does asynchronous tasks run in .NET?

Can you explain why

var value = await Task<int>.Run(() => { return 10; } );

doesn't spawn a new thread? And what it does instead?

Also, what exactly does Dispatcher.BeginInvoke on WPF?

Upvotes: 2

Views: 616

Answers (1)

usr
usr

Reputation: 171178

Tasks are run on TaskSchedulers. A scheduler can do anything but the most common default scheduler uses the CLR thread-pool. Starting a task might start a new thread or reuse an existing one. It is not necessary to be able to tell the difference.

You can force a new thread to be started using TaskCreationOptions.LongRunning.

await has nothing to do with this at all. await suspends execution of the current method until the awaited "thing" is completed. It never starts something, it only waits.

Note, that Task<int>.Run should be Task.Run. Those two expressions bind to the same method (Task.Run) but the former one is misleading.

Dispatcher.BeginInvoke has no relation to any of this. You can use this method to get an arbitrary delegate to be run on the WPF UI thread.

Upvotes: 4

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