Should I use Invoke or SynchronizationContext to u

Question

Trying to wrap my head around updating UI controls from other threads.

Currently using BeginInvoke and honestly it's working fine but I keep hearing about how you can use SynchronizationContext as well to do the same thing.

Which is preferred?

Also, is it bad practice to update the UI from a thread? Would it be better to raise an event and have the main form handle it instead or are there other preferable ways to do that as well?

Sorry for the somewhat subjective question but there are so many options in the world of threading and I'm trying to grasp their differences and where each of them are applicable, along with best practices for writing readable and extendable code for the future.

Edit: Also now I see there is the TaskScheduler.FromCurrentSynchronizationContext route as well.. So many choices x_x

Answer 1

I prefer SynchronizationContext over Control.Invoke. The danger of Control.Invoke is that there is a lifetime issue with the owning Control. If the Control is disposed while you are trying to Invoke on it then it compromises the ability of the call to succeed. This happens when dialogs are closed, views shifted, etc ...

SynchronizationContext.Current though generally lives as long as the thread it's associated with. It does have a finite lifetime and hence ultimately the same problems but it's a bit more predictable than a Control.

Answer 2

Have you looked into using a Background Worker component? For long running tasks that shouldn't tie up the UI it is a clean and easy way to get multithreading capabilites. For instance you can perform updates to the UI using the ProgressChanged Event and the background worker and the background worker class will ensure that the thread that created the BW is the one that executes the ProcessChanged and WorkComplete event. So if you made the BW from the UI and set it off to work then you can update the UI safely from there.

Here's a quick article from MS http://msdn.microsoft.com/en-us/library/cc221403%28v=vs.95%29.aspx

Another really good link http://www.albahari.com/threading/part3.aspx#_BackgroundWorker