I tried with below code to restrict the second instance of the windows service, but below code is not working for me, can anyone help me out.
I have put time interval to run service, that is 5 mints, if first instance is started and running, after 5 mints second instance is starts even though first instance is not completed.
static class Program
{
[STAThread]
static void Main()
{
bool ok;
System.Threading.Mutex m = new System.Threading.Mutex(true, "ImageImportService", out ok);
if (!ok)
{
return;
}
GC.KeepAlive(m);
if (PriorProcess() != null)
{
return;
}
ServiceBase[] ServicesToRun;
ServicesToRun = new ServiceBase[]
{
new ImageImportService()
};
ServiceBase.Run(ServicesToRun);
}
public static Process PriorProcess()
{
Process curr = Process.GetCurrentProcess();
Process[] procs = Process.GetProcessesByName(curr.ProcessName);
foreach (Process p in procs)
{
if ((p.Id != curr.Id) && (p.MainModule.FileName == curr.MainModule.FileName))
return p;
}
return null;
}
}
Service Control Manager, a component of Windows, does not allow starting a Windows service if it is already running. Just rely on it.
The main thing you need to do is to never launch your executable directly. Instead, use the ServiceController class, when starting the service from code, and Control Panel (services.msc) when starting/stopping it manually.
In some cases, you may need to take extra steps to make sure that the service does not keep any resources behind after it has been stopped, preventing its own subsequent startup until some lower level timeout. But nothing in your question indicates that you already ran into such issues (e.g., rebinding a TCP port).
I'm writing a windows phone app which stores data in a local database. There are multiple threads in my app that access the database and up until this point I have used the technique described here with an AutoResetEvent to ensure that only one thread can access the database at any one time.
So far this has worked very reliably, but now I want to add a ScheduledTask to do some work in the background so I've potentially got multiple processes now competing for access to the database.
Can anyone advise how I can adapt the AutoResetEvent technique to be used across multiple processes on Windows Phone?
I have seen approaches using a Mutex. If I acquire the Mutex before each DB call and then release it afterwards (similar to the way I'm using AutoResetEvent), will this do the trick? Is there any potential problems with this technique? eg: performance?
Ok so first of all my problem was actually 2 problems:
Need to ensure that if the foreground app is running, the background process won't run
Need to ensure that only one thread can access the databasse at once and this needs to work across processes to cater for the (admittedly rare, but possible) scenario where the foreground app is started while the background process is in progress.
Based on the good work done in this thread, I created a couple of classes to help.
To solve problem (1), I created the SingleInstanceSynchroniser:
/// <summary>
/// Used to ensure only one instance (foreground app or background app) runs at once
/// </summary>
public class SingleInstanceSynchroniser : IDisposable
{
private bool hasHandle = false;
Mutex mutex;
private void InitMutex()
{
string mutexId = "Global\\SingleInstanceSynchroniser";
mutex = new Mutex(false, mutexId);
}
public SingleInstanceSynchroniser()
{
InitMutex();
hasHandle = mutex.WaitOne(0);
}
public void Dispose()
{
if (hasHandle && mutex != null)
mutex.ReleaseMutex();
}
public bool HasExclusiveHandle { get { return hasHandle; } }
}
Usage:
In App.xaml.cs:
...
SingleInstanceSynchroniser singleInstanceSynchroniser;
public App()
{
singleInstanceSynchroniser = new SingleInstanceSynchroniser();
...
In ScheduledAgent.cs:
SingleInstanceSynchroniser singleInstanceSynchroniser;
protected override void OnInvoke(ScheduledTask task)
{
singleInstanceSynchroniser = new SingleInstanceSynchroniser();
if (singleInstanceSynchroniser.HasExclusiveHandle)
{
//Run background process
...
}
else
{ //Do not run if foreground app is running
NotifyComplete();
}
}
To solve problem (2), I created the SingleAccessSynchroniser:
/// <summary>
/// Used to ensure only one call is made to the database at once
/// </summary>
public class SingleAccessSynchroniser : IDisposable
{
public bool hasHandle = false;
Mutex mutex;
private void InitMutex()
{
string mutexId = "Global\\SingleAccessSynchroniser";
mutex = new Mutex(false, mutexId);
}
public SingleAccessSynchroniser() : this(0)
{ }
public SingleAccessSynchroniser(int TimeOut)
{
InitMutex();
if (TimeOut <= 0)
hasHandle = mutex.WaitOne();
else
hasHandle = mutex.WaitOne(TimeOut);
if (hasHandle == false)
throw new TimeoutException("Timeout waiting for exclusive access on SingleInstance");
}
public void Release()
{
if (hasHandle && mutex != null)
{
mutex.ReleaseMutex();
hasHandle = false;
}
}
public void Dispose()
{
Release();
}
}
Usage: In all database calls:
using (var dbSync = new SingleAccessSynchroniser())
{
//Execute your database calls
}
This has been running reliably for a few weeks now. Hope someone else finds it useful.
I ran into some problems using Bens solution on Windows Phone 8. Please see this thread for a complete documentation of the problems.
I was able to resolve the issues by removing "Global\" from "Global\SingleInstanceSynchroniser".
Concurrent access to a database between an agent and an app shouldn't be an issue. In fact, using Linq2SQL is one of the recommended ways for communicating between the app and agent.
In practice, it's rarely necessary for the app and agent to run at the same time and so it may be more appropriate to prevent that happening instead.
Potential performance issues will be dependent upon what you're doing. You'll need to measure this to see if it's really an issue.
I need to ban an application if it starts from the same folder, but allow it if the same application runs from other folders.
The problem is when application closes it's becomes invisible but still is in the memory because it terminates some internal job.
It's very possible that user will start this application again from the same folder quickly when the old instance still terminates in the memory.
But from the other side it should be possible if this application runs from other folders.
Any clue how to do it in C#?
UPDATES:
1
In fact application writes some logs into the local files in subdirectory and into the local database file as well. So it's very possible that it could be some conflict between 2 instances.
2
Guid appGuid = Guid.Parse("305BACEA-4074-11E1-85E1-066E4854019B");
public MainWindow()
{
InitializeComponent();
using (Mutex mutex = new Mutex(false, #"Global\" + appGuid) )
{
if (!mutex.WaitOne(0, false))
{
// MessageBox.Show("Instance already running");
// Somehow here I have to get the path of the running instance.
// If the path the same as the current instance has I have do ban starting instance.
return;
}
GC.Collect();
}
Thank you all of you!
Finally based on this post I found the solution:
public partial class App : Application
{
private Mutex _instanceMutex = null;
protected override void OnStartup(StartupEventArgs e)
{
string path = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location).Replace("\\", ".");
// check that there is only one instance of the control panel running...
bool createdNew;
_instanceMutex = new Mutex(true, path, out createdNew);
if (!createdNew)
{
_instanceMutex = null;
MessageBox.Show("Instance already running");
Application.Current.Shutdown();
return;
}
base.OnStartup(e);
}
protected override void OnExit(ExitEventArgs e)
{
if (_instanceMutex != null)
_instanceMutex.ReleaseMutex();
base.OnExit(e);
}
}
You could use a lock file to indicate that the program is already running on the folder.
When the program starts, it checks for the file in the directory. If it finds it, it shuts down, if not, it creates one and runs as normal. When the program is done, it should delete the file.
This is of course not fool proof. The file will not be deleted if the program crashes, and a user could delete the file while the program is running, bypassing the initial check.
I have a Windows Forms application that allows only one instance to be running at the time. I have implemented Singleton by using Mutex. The Application must be startable from commandline (with or without parameters). Application is started and exited by script. User can not take any action on it.
So, application purpose is simple "indicator" application that will just display some visual and graphical information for the enduser. End user can not do anything with it, just see it. It is windows forms application because then visual and graphical appearance is relatively easy implement (you can get it topmost, borderless, etc.).
To put it simply:
How can I exit the current running application when someone tries to run same application with exit commandline parameter?
bool quit = (args.Length > 0 && args[0] == "quit") ? true : false;
using (Mutex mutex = new Mutex(false, sExeName))
{
if (!mutex.WaitOne(0, true))
{
if (quit)
{
// This is the tricky part?
// How can I get reference to "previous" launced
// Windows Forms application and call it's Exit() method.
}
}
else
{
if (!quit)
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
}
}
The .NET framework offers a very good generic solution for this. Check the bottom of this MSDN magazine article. Use the StartupNextInstanceHandler() event handler to pass arbitrary commands to the running instance, like "quit".
Is this not over complicating things ? Rather than closing the existing instance and starting a new one, can you not just re-activate the existing instance? Either way round the code below should give you some ideas on how to go about it...?
Process thisProcess = Process.GetCurrentProcess();
Process[] allProcesses = Process.GetProcessesByName(thisProcess.ProcessName);
Process otherProcess = null;
foreach (Process p in allProcesses )
{
if ((p.Id != thisProcess.Id) && (p.MainModule.FileName == thisProcess.MainModule.FileName))
{
otherProcess = p;
break;
}
}
if (otherProcess != null)
{
//note IntPtr expected by API calls.
IntPtr hWnd = otherProcess.MainWindowHandle;
//restore if minimized
ShowWindow(hWnd ,1);
//bring to the front
SetForegroundWindow (hWnd);
}
else
{
//run your app here
}
There is another question about this here
This is a somewhat quick-and-dirty solution which you would probably want to refine:
[STAThread]
static void Main()
{
var me = Process.GetCurrentProcess();
var otherMe = Process.GetProcessesByName(me.ProcessName).Where(p => p.Id != me.Id).FirstOrDefault();
if (otherMe != null)
{
otherMe.Kill();
}
else
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
}
If an instance of the app is already started, that process is killed; otherwise the app starts normally.
I think the easiest way is the following
see the link
http://codenicely.blogspot.com/2010/04/creating-forms-object.html
In .NET, what's the best way to prevent multiple instances of an app from running at the same time? And if there's no "best" technique, what are some of the caveats to consider with each solution?
Use Mutex. One of the examples above using GetProcessByName has many caveats. Here is a good article on the subject:
http://odetocode.com/Blogs/scott/archive/2004/08/20/401.aspx
[STAThread]
static void Main()
{
using(Mutex mutex = new Mutex(false, "Global\\" + appGuid))
{
if(!mutex.WaitOne(0, false))
{
MessageBox.Show("Instance already running");
return;
}
Application.Run(new Form1());
}
}
private static string appGuid = "c0a76b5a-12ab-45c5-b9d9-d693faa6e7b9";
if (Process.GetProcessesByName(Process.GetCurrentProcess().ProcessName).Length > 1)
{
AppLog.Write("Application XXXX already running. Only one instance of this application is allowed", AppLog.LogMessageType.Warn);
return;
}
Here is the code you need to ensure that only one instance is running. This is the method of using a named mutex.
public class Program
{
static System.Threading.Mutex singleton = new Mutex(true, "My App Name");
static void Main(string[] args)
{
if (!singleton.WaitOne(TimeSpan.Zero, true))
{
//there is already another instance running!
Application.Exit();
}
}
}
Hanselman has a post on using the WinFormsApplicationBase class from the Microsoft.VisualBasic assembly to do this.
1 - Create a reference in program.cs ->
using System.Diagnostics;
2 - Put into void Main() as the first line of code ->
if (Process.GetProcessesByName(Process.GetCurrentProcess().ProcessName).Length >1)
return;
That's it.
After trying multiple solutions i the question. I ended up using the example for WPF here: http://www.c-sharpcorner.com/UploadFile/f9f215/how-to-restrict-the-application-to-just-one-instance/
public partial class App : Application
{
private static Mutex _mutex = null;
protected override void OnStartup(StartupEventArgs e)
{
const string appName = "MyAppName";
bool createdNew;
_mutex = new Mutex(true, appName, out createdNew);
if (!createdNew)
{
//app is already running! Exiting the application
Application.Current.Shutdown();
}
}
}
In App.xaml:
x:Class="*YourNameSpace*.App"
StartupUri="MainWindow.xaml"
Startup="App_Startup"
It sounds like there are 3 fundamental techniques that have been suggested so far.
Derive from the Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase class and set the IsSingleInstance property to true. (I believe a caveat here is that this won't work with WPF applications, will it?)
Use a named mutex and check if it's already been created.
Get a list of running processes and compare the names of the processes. (This has the caveat of requiring your process name to be unique relative to any other processes running on a given user's machine.)
Any caveats I've missed?
i tried all the solutions here and nothing worked in my C# .net 4.0 project. Hoping to help someone here the solution that worked for me:
As main class variables:
private static string appGuid = "WRITE AN UNIQUE GUID HERE";
private static Mutex mutex;
When you need to check if app is already running:
bool mutexCreated;
mutex = new Mutex(true, "Global\\" + appGuid, out mutexCreated);
if (mutexCreated)
mutex.ReleaseMutex();
if (!mutexCreated)
{
//App is already running, close this!
Environment.Exit(0); //i used this because its a console app
}
I needed to close other istances only with some conditions, this worked well for my purpose
Using Visual Studio 2005 or 2008 when you create a project for an executable, on the properties windows inside the "Application" panel there is a check box named “Make single instance application” that you can activate to convert the application on a single instance application.
Here is a capture of the window I'm talking of:
This is a Visual Studio 2008 windows application project.
http://en.csharp-online.net/Application_Architecture_in_Windows_Forms_2.0—Single-Instance_Detection_and_Management
This is the code for VB.Net
Private Shared Sub Main()
Using mutex As New Mutex(False, appGuid)
If Not mutex.WaitOne(0, False) Then
MessageBox.Show("Instance already running", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error)
Return
End If
Application.Run(New Form1())
End Using
End Sub
This is the code for C#
private static void Main()
{
using (Mutex mutex = new Mutex(false, appGuid)) {
if (!mutex.WaitOne(0, false)) {
MessageBox.Show("Instance already running", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error);
return;
}
Application.Run(new Form1());
}
}
Use VB.NET!
No: really ;)
using Microsoft.VisualBasic.ApplicationServices;
The WindowsFormsApplicationBase from VB.Net provides you with a "SingleInstace" Property, which determines other Instances and let only one Instance run.
[STAThread]
static void Main() // args are OK here, of course
{
bool ok;
m = new System.Threading.Mutex(true, "YourNameHere", out ok);
if (! ok)
{
MessageBox.Show("Another instance is already running.");
return;
}
Application.Run(new Form1()); // or whatever was there
GC.KeepAlive(m); // important!
}
From: Ensuring a single instance of .NET Application
and: Single Instance Application Mutex
Same answer as #Smink and #Imjustpondering with a twist:
Jon Skeet's FAQ on C# to find out why GC.KeepAlive matters
This article simply explains how you can create a windows application with control on the number of its instances or run only single instance. This is very typical need of a business application. There are already lots of other possible solutions to control this.
https://web.archive.org/web/20090205153420/http://www.openwinforms.com/single_instance_application.html
http://www.codeproject.com/KB/cs/SingleInstancingWithIpc.aspx
You have to use System.Diagnostics.Process.
Check out: http://www.devx.com/tips/Tip/20044
(Note: this is a fun-solution! It works but uses bad GDI+ design to achieve this.)
Put an image in with your app and load it on startup. Hold it until the app exits. The user wont be able to start a 2nd instance. (Of course the mutex solution is much cleaner)
private static Bitmap randomName = new Bitmap("my_image.jpg");
Simply using a StreamWriter, how about this?
System.IO.File.StreamWriter OpenFlag = null; //globally
and
try
{
OpenFlag = new StreamWriter(Path.GetTempPath() + "OpenedIfRunning");
}
catch (System.IO.IOException) //file in use
{
Environment.Exit(0);
}
Normally it's done with a named Mutex (use new Mutex( "your app name", true ) and check the return value), but there's also some support classes in Microsoft.VisualBasic.dll that can do it for you.
This worked for me in pure C#. the try/catch is when possibly a process in the list exits during your loop.
using System.Diagnostics;
....
[STAThread]
static void Main()
{
...
int procCount = 0;
foreach (Process pp in Process.GetProcesses())
{
try
{
if (String.Compare(pp.MainModule.FileName, Application.ExecutablePath, true) == 0)
{
procCount++;
if(procCount > 1) {
Application.Exit();
return;
}
}
}
catch { }
}
Application.Run(new Form1());
}
Be sure to consider security when restricting an application to a single instance:
Full article:
https://blogs.msdn.microsoft.com/oldnewthing/20060620-13/?p=30813
We are using a named mutex with a fixed name in order to detect
whether another copy of the program is running. But that also means an
attacker can create the mutex first, thereby preventing our program
from running at all! How can I prevent this type of denial of service
attack?
...
If the attacker is running in the same security context as your
program is (or would be) running in, then there is nothing you can do.
Whatever "secret handshake" you come up with to determine whether
another copy of your program is running, the attacker can mimic it.
Since it is running in the correct security context, it can do
anything that the "real" program can do.
...
Clearly you can't protect yourself from an attacker running at the
same security privilege, but you can still protect yourself against
unprivileged attackers running at other security privileges.
Try setting a DACL on your mutex, here's the .NET way:
https://msdn.microsoft.com/en-us/library/system.security.accesscontrol.mutexsecurity(v=vs.110).aspx
None of this answers worked for me because I needed this to work under Linux using monodevelop. This works great for me:
Call this method passing it a unique ID
public static void PreventMultipleInstance(string applicationId)
{
// Under Windows this is:
// C:\Users\SomeUser\AppData\Local\Temp\
// Linux this is:
// /tmp/
var temporaryDirectory = Path.GetTempPath();
// Application ID (Make sure this guid is different accross your different applications!
var applicationGuid = applicationId + ".process-lock";
// file that will serve as our lock
var fileFulePath = Path.Combine(temporaryDirectory, applicationGuid);
try
{
// Prevents other processes from reading from or writing to this file
var _InstanceLock = new FileStream(fileFulePath, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None);
_InstanceLock.Lock(0, 0);
MonoApp.Logger.LogToDisk(LogType.Notification, "04ZH-EQP0", "Aquired Lock", fileFulePath);
// todo investigate why we need a reference to file stream. Without this GC releases the lock!
System.Timers.Timer t = new System.Timers.Timer()
{
Interval = 500000,
Enabled = true,
};
t.Elapsed += (a, b) =>
{
try
{
_InstanceLock.Lock(0, 0);
}
catch
{
MonoApp.Logger.Log(LogType.Error, "AOI7-QMCT", "Unable to lock file");
}
};
t.Start();
}
catch
{
// Terminate application because another instance with this ID is running
Environment.Exit(102534);
}
}