You can grab the UI Dispatcher from the static application instance: `Application.Current.Dispatcher` 

You may want to check `Application.Current` for null first, as it can be cleared during a shutdown sequence.

The following works much better for me when being used in a WinForms application that happens to be also using WPF (in my case Esri&#39;s Arcmap.exe)

    private System.Windows.Threading.Dispatcher Dispatcher { get; set; }

    // I put this in my view model constructor as it MUST be called from UI thread
    Dispatcher = System.Windows.Threading.Dispatcher.CurrentDispatcher;

The other method (which involved calling `new System.Windows.Application()` to populate `System.Windows.Application.Current`) caused issues for me every time I opened a new WPF window and then closed it.  Not only did this null out `System.Windows.Application.Current`, but I could no longer open up new windows as their `InitializeComponents()` methods, all failed with: 

&gt; System.InvalidOperationException: &#39;The Application object is being
&gt; shut down.&#39;

So far the new solution is working without those side effects.

Visual Studio drives me crazy and I am suspecting I am doing something wrong.

This is what I do: I installed Visual Studio (Pro &#39;08) a long time ago, I installed the Windows SDK (Win 7 x64), someone emails me a project, it fails to build.

Invariably, it can not find windows.h. While it is easy enough to include `C:\Program Files\Microsoft SDKs\Windows\v7.0\Include` in the project settings of every single project, I feel that this may not be the proper way to do it. Is there a way to somehow make Visual Studio globally aware of these files?  
I also tried to include the above directory in the `path` variable but that didn&#39;t change anything.

Also, it will randomly find windows.h but not winresrc.h in the same directory.

__Edit:__  
It was a problem with my machine. Somehow, Visual Studio thought that my Windows SDK was in the wrong place. See accepted answer and comments for the fix.

How do include paths work in Visual Studio?

In my algorithm, I need to create an information output. I need to write a boolean matrix into a bmp file.
It must be a monocromic image, where pixels are white if the matrix on such element is true.
Main problem is the bmp header and how to write this.


Writing BMP image in pure c/c++ without other libraries

Is there any way to get the UI thread&#39;s `Dispatcher` when you have no reference to any UI elements?

How do I get the UI thread&#39;s Dispatcher?

<p>Is there any way to get the UI thread's <code>Dispatcher</code> when you have no reference to any UI elements?</p>


Before going much further i&#39;ll mention I have tried solutions in following:

https://stackoverflow.com/questions/320677/how-do-i-set-the-icon-for-my-application-in-visual-studio-2008

https://stackoverflow.com/questions/198848/set-application-icon-from-resources-in-vs-05

I am trying to set an icon for my application.

AFAIK, I need potentially 3 images?

- 1 image is the actual image in explorer when clicking on the .exe (thumbnail for the exe)
- 1 image (tiny) in the top left corner (16 x 16? Not entirely sure)
- 1 image in the start menu dock, to the left of the app (maybe 32x32? again not sure)

So thats fine.

Now I have selected an Icon. How do I use it in one of above situations?

I have tried adding it in resources, nothing seems to happen. Following that first SO solution, 

&lt;i&gt;&quot;First go to Resource View (from menu: View --&gt; Other Window --&gt; Resource View). Then in Resource View navigate through resources, if any. If there is already a resource of Icon type, added by Visual Studio, then open and edit it. Otherwise right-click and select Add Resource, and then add a new icon.&quot;&lt;/i&gt;

The resource view is empty, and I cannot right click in this view.

If I right click on the solution &gt; properties &gt; resources &gt; I can add the icon image, but it doesn&#39;t show in either of the locations listed above. (or anywhere that I can see)

**1) How do I set the application icon for a WPF Application?**

Setting Icon for wpf application (VS 08)

I&#39;ve been playing around with C# console applications for about a year and I want to move on to creating GUI applications. I have never done any GUI development besides basic Java applications, but I want to continue using C#. Should I start learning Windows Forms or jump straight to WPF? Is there a huge difference? Does WPF build on top of Windows Forms or are they totally different?

WPF or Windows Forms

Does anyone know opensource WPF applications created using MVVM Light Toolkit? Or any samples?

MVVM Light Toolkit samples

I am a beginner when it comes to programming but I was sure that one of the universal rules was that a program starts with Main(). I do not see one when I create a WPF project. Is Main() simply named something differently in WPF?

No Main() in WPF?

I&#39;m trying to attach an image on a button in WPF, however this code fails.  Seems strange after similar code would work perfectly in Mozilla XUL.

    &lt;Button Height=&quot;49.086&quot; Margin=&quot;3.636,12,231.795,0&quot; Name=&quot;button2&quot; 
            VerticalAlignment=&quot;Top&quot; Grid.Column=&quot;1&quot; Click=&quot;button2_Click&quot; 
            Source=&quot;Pictures/apple.jpg&quot;&gt;Disconnect from Server&lt;/Button&gt;

WPF Button with Image

If I have two multiple threads accessing a HashMap, but guarantee that they&#39;ll never be accessing the same key at the same time, could that still lead to a race condition?

Is a HashMap thread-safe for different keys?

The following code does not exit the application. How can I exit the application and make sure all the running threads are closed?

    foreach (Form form in Application.OpenForms)
    {
        form.Close();
    }
    Application.Exit();



How to exit all running threads?

I&#39;m using `LinkedBlockingQueue` between two different threads. One thread adds data via `add`, while the other thread receives data via `take`.

My question is, do I need to synchronize access to `add` and `take`. Is `LinkedBlockingQueue`&#39;s insert and remove methods thread safe?

Are LinkedBlockingQueue&#39;s insert and remove methods thread safe?

My application spawns loads of different small worker threads via `ThreadPool.QueueUserWorkItem` which I keep track of via multiple `ManualResetEvent` instances. I use the `WaitHandle.WaitAll` method to block my application from closing until these threads have completed.

I have never had any issues before, however, as my application is coming under more load i.e. more threads being created, I am now beginning to get this exception:

`WaitHandles must be less than or equal to 64 - missing documentation`

What is the best alternative solution to this?

&lt;b&gt; Code Snippet &lt;/b&gt;

    List&lt;AutoResetEvent&gt; events = new List&lt;AutoResetEvent&gt;();

    // multiple instances of...
    var evt = new AutoResetEvent(false);
    events.Add(evt);
    ThreadPool.QueueUserWorkItem(delegate
    {
        // do work
        evt.Set();
    });

    ...
    WaitHandle.WaitAll(events.ToArray());

&lt;b&gt; Workaround &lt;/b&gt;

    int threadCount = 0;
    ManualResetEvent finished = new ManualResetEvent(false);

    ...
    Interlocked.Increment(ref threadCount);
    ThreadPool.QueueUserWorkItem(delegate
    {
        try
        {
             // do work
        }
        finally
        {
            if (Interlocked.Decrement(ref threadCount) == 0)
            {
                 finished.Set();
            }
        }
    });

    ...
    finished.WaitOne();

Workaround for the WaitHandle.WaitAll 64 handle limit?

Erlang&#39;s Characteristics
-----------------------

From [Erlang Programming][1] (2009):
&gt;Erlang concurrency is fast and scalable. Its processes are lightweight in that the Erlang virtual machine does not create an OS thread for every created process. They are created, scheduled, and handled in the VM, independent of underlying operating system. As a result, process creation time is of the order of microseconds and independent of the number of concurrently existing processes. Compare this with Java and C#, where for every process an underlying OS thread is created: you will get some very competitive comparisons, with Erlang greatly outperforming both languages.


From [ Concurrency oriented programming in Erlang (pdf)][2] [(slides)][3] (2003):

&gt;We observe that the time taken to create an Erlang process is constant 1&#181;s up to 2,500 processes; thereafter it increases to about 3&#181;s for up to 30,000 processes. The performance of Java and C# is shown at the top of the figure. For a small number of processes it takes about 300&#181;s to create a process. Creating more than two thousand processes is impossible.
&gt;
&gt;We see that for up to 30,000 processes the time to send a message between two Erlang processes is about 0.8&#181;s. For C# it takes about 50&#181;s per message, up to the maximum number of processes (which was about 1800 processes). Java was even worse, for up to 100 process it took about 50&#181;s per message thereafter it increased rapidly to 10ms per message when there were about 1000 Java processes.

My thoughts
-----------

I don&#39;t fully understand technically why Erlang processes are so much more efficient in spawning new processes and have much smaller memory footprints per process. Both the OS and Erlang VM have to do scheduling, context switches, and keep track of the values in the registers and so on...

Simply why aren&#39;t OS threads implemented in the same way as processes in Erlang? Do they have to support something more? And why do they need a bigger memory footprint? And why do they have slower spawning and communication?

Technically, why are processes in Erlang more efficient than OS threads when it comes to spawning and communication? And why can&#39;t threads in the OS be implemented and managed in the same efficient way? And why do OS threads have a bigger memory footprint, plus slower spawning and communication?

More reading
------------
* [Inside the Erlang VM *with focus on SMP*][5] (2008)
* [Concurrency in Java and in Erlang (pdf)][4] (2004)
* [Performance Measurements of Threads in Java and Processes in Erlang][6] (1998)


  [1]: http://www.amazon.com/ERLANG-Programming-Francesco-Cesarini/dp/0596518188/
  [2]: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.116.1969&amp;rep=rep1&amp;type=pdf
  [3]: http://www.scribd.com/doc/6505089/Concurrency-Oriented-Programming-in-Erlang-by-Joe-Armstrong
  [4]: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.1.9502&amp;rep=rep1&amp;type=pdf
  [5]: https://erlang.org/euc/08/euc_smp.pdf
  [6]: http://www.sics.se/~joe/ericsson/du98024.html

Technically, why are processes in Erlang more efficient than OS threads?

I&#39;m trying to call `System.Windows.Threading.Dispatcher.BeginInvoke`. The signature of the method is this:

    BeginInvoke(Delegate method, params object[] args)

I&#39;m trying to pass it a Lambda instead of having to create a Delegate.

    _dispatcher.BeginInvoke((sender) =&gt; { DoSomething(); }, new object[] { this } );

It&#39;s giving me a compiler error saying that I 

&gt; can&#39;t convert the lambda to a System.Delegate. 

The signature of the delegate takes an object as a parameter and returns void. My lambda matches this, yet it&#39;s not working. What am I missing?

Dispatcher.BeginInvoke: Cannot convert lambda to System.Delegate

Neither of these work:

    _uiDispatcher.Invoke(() =&gt; { });
    _uiDispatcher.Invoke(delegate() { });

All I want to do is Invoke an inline method on my main UI thread. So I called this on the main thread:

    _uiDispatcher = Dispatcher.CurrentDispatcher;

And now I want to execute some code on that thread from another thread. How do I do it? Am I using the wrong syntax?

Note that this is *not* a WPF application; I&#39;ve referenced `WindowsBase` so I could get access to the `Dispatcher` class.

Cannot convert lambda expression to type &#39;System.Delegate&#39;

What are the differences between `Dispatcher.CurrentDispatcher` (in `System.Windows.Threading`) and `Application.Current.Dispatcher` (in `System.Windows`)?

My gut tells me that `Application.Current.Dispatcher` will never change and is global to all threads in the current application, while `Dispatcher.CurrentDispatcher` may create a new instance of `Dispatcher` depending on the thread from which it was called.

Is that correct?

If it is, is the purpose of `Dispatcher.CurrentDispatcher` primarily for multi-threaded UI?

Dispatcher.CurrentDispatcher vs. Application.Current.Dispatcher

How can I run code on the UI thread in WinRT (Windows 8 Metro)?

The `Invoke` method does not exist.


Run code on UI thread in WinRT

I&#39;m building a Windows Store app, and I have some code that needs to be posted to the UI thread.

For that, i&#39;d like to retrieve the CoreDispatcher and use it to post the code.

It seems that there are a few ways to do so:

    // First way
    Windows.ApplicationModel.Core.CoreApplication.GetCurrentView().CoreWindow.Dispatcher;
    
    // Second way
    Window.Current.Dispatcher;


I wonder which one is correct? or if both are equivalent?

Content Type	Original Author	Original Content on Stackoverflow
Question	Peter	View Question on Stackoverflow
Solution 1 - Wpf	Abe Heidebrecht	View Answer on Stackoverflow
Solution 2 - Wpf	M Townsend	View Answer on Stackoverflow

How do I get the UI thread's Dispatcher?

Wpf Problem Overview

Wpf Solutions

Solution 1 - Wpf

Solution 2 - Wpf

Writing BMP image in pure c/c++ without other libraries

How do include paths work in Visual Studio?

Attributions