WPF Databinding thread safety?

Question

Well lets say i have an object that i databind to, it implements INotifyPropertyChanged to tell the GUI when a value has changed...

if i trigger this from a different thread than the GUI thread how would wpf behave?

and will it make sure that it gets the value of the property from memory and not the cpu cache?

more or less im asking if wpf does lock() on the object containing the property...

Answer 1

In practice it seems to work as expected and seems to be thread-safe (haven't seen anything odd happen or exceptions as a result of updating on background thread). I believe it invokes on to the UI thread when needed, but I'm not too familiar with the internals.

Answer 2

The update must happen on UI thread otherwise app will crash.

Answer 3

Value changes fired by INotifyPropertyChanged are automatically marshalled back onto the dispatcher. (http://blog.lab49.com/archives/1166)

Fire this event on any thread you like...

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Value changes fired by INotifyCollectionChanged are NOT reliably marshalled onto the dispatcher. (http://csharplive.wordpress.com/2008/09/11/wpf-data-binding-observablecollection-cross-thread-binding-support/)

If you need to update an observable collection from a different thread, follow the advice in this link

Answer 4

Value changes fired by INotifyCollectionChanged are NOT reliably marshalled onto the dispatcher. (http://csharplive.wordpress.com/2008/09/11/wpf-data-binding-observablecollection-cross-thread-binding-support/)

Wow, this is large overhead for thread safety. Is there a reason for not using the DispatcherObject.CheckAccess() approach? I use it and it works.