dispatcher – Tarik Billa

No WebApplicationContext found: no ContextLoaderListener registered?

April 8, 2024 by Tarik

You’ll have to have a ContextLoaderListener in your web.xml – It loads your configuration files. <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> You need to understand the difference between Web application context and root application context . In the web MVC framework, each DispatcherServlet has its own WebApplicationContext, which inherits all the beans already defined in the root WebApplicationContext. … Read more

WPF BackgroundWorker vs. Dispatcher

December 15, 2023 by Tarik

The main difference between the Dispatcher and other threading methods is that the Dispatcher is not actually multi-threaded. The Dispatcher governs the controls, which need a single thread to function properly; the BeginInvoke method of the Dispatcher queues events for later execution (depending on priority etc.), but still on the same thread. BackgroundWorker on the … Read more

What are the default Akka dispatcher configuration values?

December 12, 2023 by Tarik

By default the dispatcher provided by Akka is one with a fork-join-executor, and the default parallelism values are these: parallelism-min: 8 parallelism-factor: 3.0 parallelism-max: 64 You can see all of this in the documentation. There is a section named: Listing of the Reference Configuration Here is the relevant part of the configuration file (I only … Read more

How to return a value with Dispatcher.Invoke?

December 1, 2023 by Tarik

There’s another way that returns value from Invoke(): object oIsLoaded = container.Dispatcher.Invoke( new Func<bool> ( () => { return container.IsLoaded; }) ); And by the way, chances are that the initial code (which is working with delegate) won’t modify oIsLoaded at all; So I’d rather use a Func<> for returning a value from that kind … Read more

System.Windows.Threading.Dispatcher and WinForms?

September 20, 2023 by Tarik

You can use Dispatcher even in a WinForms app. If you are sure to be on a UI thread (e.g. in an button.Click handler), Dispatcher.CurrentDispatcher gives you the UI thread dispatcher that you can later use to dispatch from background threads to the UI thread as usual.

c# – Volatile keyword usage vs lock

August 28, 2023 by Tarik

I’ve used volatile where I’m not sure it is necessary. Let me be very clear on this point: If you are not 100% clear on what volatile means in C# then do not use it. It is a sharp tool that is meant to be used by experts only. If you cannot describe what all … Read more

Ensuring that things run on the UI thread in WPF

August 25, 2023 by Tarik

Going over each of your questions, one by one: Not quite; you should only invoke onto the UI thread when necessary. See #2. Yes, it does matter. You should not just automatically Invoke everything. The key is to only invoke onto the UI thread if necessary. To do this, you can use the Dispatcher.CheckAccess method. … Read more

Dispatcher Invoke(…) vs BeginInvoke(…) confusion

July 22, 2023 by Tarik

When you use Dispatcher.BeginInvoke it means that it schedules the given action for execution in the UI thread at a later point in time, and then returns control to allow the current thread to continue executing. Invoke blocks the caller until the scheduled action finishes. When you use BeginInvoke your loop is going to run … Read more

How to put delay before doing an operation in WPF

May 25, 2023 by Tarik

The call to Thread.Sleep is blocking the UI thread. You need to wait asynchronously. Method 1: use a DispatcherTimer tbkLabel.Text = “two seconds delay”; var timer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(2) }; timer.Start(); timer.Tick += (sender, args) => { timer.Stop(); var page = new Page2(); page.Show(); }; Method 2: use Task.Delay tbkLabel.Text = … Read more

Using the WPF Dispatcher in unit tests

April 22, 2023 by Tarik

By using the Visual Studio Unit Test Framework you don’t need to initialize the Dispatcher yourself. You are absolutely right, that the Dispatcher doesn’t automatically process its queue. You can write a simple helper method “DispatcherUtil.DoEvents()” which tells the Dispatcher to process its queue. C# Code: public static class DispatcherUtil { [SecurityPermissionAttribute(SecurityAction.Demand, Flags = SecurityPermissionFlag.UnmanagedCode)] … Read more