Is WPF Dispatcher the solution of multi threading problems?

The main issue with using the Dispatcher (or BackgroundWorker) is that it's difficult to test, unless your testing harness actually has a UI thread.

Solution 1

Use the SynchronizationContext. It provides the same ability to invoke on the UI thread and works in Windows or WPF. Testing it also possible.

Solution 2

Think of the dispatcher as being just another service. As you use PRISM, you are familiar with services and IOC. Here is how such a service may be used:

// Not a UI component
public class MyDomainService : IMyDomainService
{
   private readonly IDispatcher _dispatcher;

   public MyDomainService(IDispatcher dispatcher) 
   {
      _dispatcher = dispatcher;
   }

   private void GotResultFromBackgroundThread()
   {
       _dispatcher.Dispatch(() => DoStuffOnForegroundThread());
   }
}

This allows you to substitute in different implementations for your platform/testing.

Here is an example of IDispatcher, a WPF implementation and a test implementation. You would register them with your IOC container just like any other service, and they are available to both UI and other services.

yes and no.. its a rendering thing..not a threading thing per se..

The Dispatcher selects work items on a priority basis and runs each one to completion. Every UI thread must have at least one Dispatcher, and each Dispatcher can execute work items in exactly one thread. as per this this link from Microsoft.

You still have to handle on your own any threads you start yourself.

Check this one for info on: Multithreaded Programming with the Event-based Asynchronous Pattern

Personally I use the Background Worker for my threading needs.

Best Practices here.