Windows application framework properties single instance

The word mutex is short for mutual exclusion, and is a synchronisation object that can only be owned by a single thread at any given time. Specifying a name for the mutex is optional - an unnamed mutex is scoped to the current process, while a named one is associated with an operating system object and can thus be used for interprocess synchronisation. Quite simply then, we can launch our application like in code in mentioned above. That ensures that there's only a single instance of our application running.

Have you tried making it a "single-instance application"? My VS Help says With a project selected in Solution Explorer , on the Project menu, click Properties. I haven't found any statements as to whether this means single instance per user or single instance on one computer, but it might be worth an experiment. I'm trying to do the same thing in wpf application, but for some reason, it doesn't work there Ask a question. Quick access. Search related threads. An IDictionary that contains the application-scope properties.

The following example shows how create and use an application-scope property using Properties. Application exposes a dictionary via Properties which you can use to store application-scope properties. This allows you to share state amongst all code in an AppDomain in a thread-safe fashion, without the need to write your own state code. Properties stored in Properties must be converted to the appropriate type returned.

The Properties property is thread safe and is available from any thread. Skip to main content. I let my previous answer just as reference Just as reference, this is how I did without passing arguments which I can't find any reason to do so I mean a single app with arguments that as to be passed out from one instance to another one.

If file association is required, then an app should per users standard expectation be instanciated for each doc. If you have to pass args to existing app, I think I would used vb dll. Not passing args just single instance app , I prefer not registering a new Window message and not override the message loop as defined in Matt Davis Solution. Although it's not a big deal to add a VisualBasic dll, but I prefer not add a new reference just to do single instance app.

Also, I do prefer instanciate a new class with Main instead of calling Shutdown from App. Startup override to ensure to exit as soon as possible. You can add MessageBox. Show to the if -statement and put "Application already running". This might be helpful to someone. You only have to check the value of the createdNew variable example below! Apparently the postmessage method dosent work, if the application is not show in the taskbar, however using the sendmessage method solves this.

Named-mutex-based approaches are not cross-platform because named mutexes are not global in Mono. Process-enumeration-based approaches don't have any synchronization and may result in incorrect behavior e. Windowing-system-based approaches are not desirable in a console application.

This solution, built on top of Divin's answer, addresses all these issues:. I use Mutex in my solution for preventing multiple instances. Here's a lightweight solution I use which allows the application to bring an already existing window to the foreground without resorting to custom windows messages or blindly searching process names. Personally, I prefer keeping the mutex local as it will be automatically disposed of even if the application closes without ever reaching the end of Main.

This is how I ended up taking care of this issue. Note that debug code is still in there for testing. This code is within the OnStartup in the App. Please check the proposed solution from here that uses a semaphore to determine if an existing instance is already running, works for a WPF application and can pass arguments from second instance to the first already running instance by using a TcpListener and a TcpClient:. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. What is the correct way to create a single-instance WPF application? Ask Question. Asked 13 years, 4 months ago. Active 2 months ago. Viewed k times. Improve this question. Nidonocu Nidonocu Doesn't the CLR automatically release any unreleased mutexes when the application terminates anyway?

Cocowalla: the finalizer should dispose the unmanaged mutexes unless it can't know if the mutex was created by the managed app or attached to an existing one. Having only one instance of your app is reasonable.

But passing arguments to an already existing app appears to me a bit silly. I can't see any reason to do so. If you associate an app with file extension, you should open as many app as user want to open documents. That's the standard behavior which every users would expect.

Cocowalla The CLR does not manage native resources. I prefer the answer by huseyint. It uses Microsoft's own 'SingleInstance. Also, no dependency on VisualBasic yuk. See codereview. Show 2 more comments. Active Oldest Votes. WaitOne TimeSpan.

EnableVisualStyles ; Application. Run new Form1 ; mutex. Here is what I ended up with: Program. Zero, IntPtr.

Improve this answer. StayOnTarget 8, 9 9 gold badges 43 43 silver badges 66 66 bronze badges. Matt Davis Matt Davis On the basis that this answer uses less code and less libraries and provides the raise to top functionality, I'm going to make this the new accepted answer.

If anyone knows a more correct way to bring the form to the top using API's, feel free to add that. BlueRaja, you start up the first app instance. When you start up the second app instance, it detects that another instance is already running and prepares to shutdown. Before doing so, it sends a "SHOWME" native message to the first instance, which brings the first instance to the top.

Events in. NET don't allow cross-process communication, which is why the native message is used. Is there a way to pass the command lines from the other instance, maybe? Nam, the Mutex constructor simply requires a string, so you could supply any string name you want, e.

Because a 'Mutex' is a system object that is available to other processes, you typically want the name to be unique so it doesn't clash with other 'Mutex' names on the same system. In the article, the cryptic-looking string is a 'Guid'. You can generate this programmatically by calling System. In the case of the article, the user probably generated it via Visual Studio as shown here: msdn.

Does the mutex approach assume that the same user is attempting to start the application again? Certainly bringing "the existing instance of the application to the foreground" does not make sense after a 'switch user' — dumbledad. Show 35 more comments. Dale Ragan Dale Ragan I'd stick with the mutex solution because it has nothing to do with forms.

I've used this because I had issues with other approaches, but I'm fairly sure it uses remoting under the hood. My app has had two related issues - some customers say it tries to phone home even though they've told it not to.

When they look more carefully, the connection is to localhost. Still, they don't initially know that. Also, I can't use remoting for a different purpose I think? When I tried the mutex approach, I could then use remoting again. Forgive me, but unless I a missing something, you avoided writing 3 lines of code and instead you re-used framework just to write pretty heavy code to do it.

So where are the savings? If you don't call InitializeComponent on the application instance, you won't be able to resolve resources Run ; — Nick. Show 5 more comments. WriteLine "Another instance of the app is running. WriteLine "Running - press Enter to exit" ; Console. I've got to say, I like this answer a lot more than the accepted one simply due to the fact that it isn't dependent on WinForms.

Personally most of my development has been moving to WPF and I don't want to have to pull in WinForm libraries for something like this. Of course, to be a full answer, you have to also describe passing the arguments to the other instance : — Simon Buchan. Jason, good, thanks! But I prefer not passing any timeout.

It is so much subjective and depends on so many variables. If you ever want to enable another app to start, just release your mutex quicker.. If you have a good reason to have a "master" process say you have a in-proc DB for settings you might want to have it show UI as if it were a new process too. Simon, you are right. I just question myself about a very old thing When you talk about tabs, you refer to MDI. In , a Microsoft book suggests to eliminate every MDI app. Microsoft switched Word, Excel But I understand better the question asked now.

Show 1 more comment. Because of this and what Scott Hanselman says and the fact that this pretty much is the cleanest solution to the problem and is designed by people who know a lot more about the framework than you do.

From a usability standpoint the fact is if your user is loading an application and it is already open and you're giving them an error message like 'Another instance of the app is running. Bye' then they're not gonna be a very happy user. You simply MUST in a GUI application switch to that application and pass in the arguments provided - or if command line parameters have no meaning then you must pop up the application which may have been minimized.

Community Bot 1 1 1 silver badge. Thank you for including the 'take a look at this too' link. That's exactly what I needed. By the way, solution 3 in your link is the best one. I am also an advocate of delegating to the framework and specially designed libraries where possible.

Add a comment. GetProcesses where process. Equals currentProcess. ProcessName, StringComparison. Ordinal select process. FirstOrDefault ; if runningProcess! GetProcessesByName procName ; if processes. CharithJ CharithJ Also, this won't work if there's any other program running on your computer with the same name. ProcessName returns the executable file name minus the exe. If you make an application called "Notepad", and the windows notepad is running, it'll detect it as your application running.

Thanks for this answer. This one Method 1 is straightforward, clear and most of all it actually helped me make my code run. FullName, out this. ThrowIfDisposed ; this. Dispose true ; GC. Oliver Friedrich Oliver Friedrich 8, 7 7 gold badges 40 40 silver badges 48 48 bronze badges.

It would not close the second application until I changed Application. Exit ; to a simple return; but other than that its great. Although i admit I am going to look at the previous solution closer since it uses an interface.

Peter Mortensen I use this with great success. If you incorporate NamedPipes with this, you can also pass command-line arguments to the original application. The class, 'SingleInstance. I have added another link to a more readable version of Arik Poznanski's blog on CodeProject.