In dotnet core how can I ensure only one copy of my application is running? - singleton

Question

In the past I have done something like this
private static bool AlreadyRunning()
{
var processes = Process.GetProcesses();
var currentProc = Process.GetCurrentProcess();
logger.Info($"Current proccess: {currentProc.ProcessName}");
foreach (var process in processes)
{
if (currentProc.ProcessName == process.ProcessName && currentProc.Id != process.Id)
{
logger.Info($"Another instance of this process is already running: {process.Id}");
return true;
}
}
return false;
}
Which has worked well. In the new dotnet core world everything has a process name of dotnet so I can only run one dotnet app at a time! Not quite what I want :D
Is there an ideal way of doing this in dotnet? I see mutex suggested but I am not sure I understand the possible downsides or error states running on other systems than a windows machine.

Answer 1

.NET Core now supports global named mutex. From PR description, that added that functionality:
On systems that support thread process-shared robust recursive mutexes, they will be used
On other systems, file locks are used. File locks, unfortunately, don't have a timeout in the blocking wait call, and I didn't find any other sync object with a timed wait with the necessary properties, so polling is done for timed waits.
Also, there is a useful note in Named mutex not supported on Unix issue about mutex name, that should be used:
By default, names have session scope and sessions are more granular on Unix (each terminal gets its own session). Try adding a "Global" prefix to the name minus the quotes.

Answer 2

In the end I used a mutex and it seeeeeems okay.
I grabbed the code from here
What is a good pattern for using a Global Mutex in C#?
The version of core I am using does not seem to have some of the security settings stuff so I just deleted it. I am sure it will be fine. (new Mutex only takes 3 parameters)
private static void Main(string[] args)
{
LogManager.Configuration = new XmlLoggingConfiguration("nlog.config");
logger = LogManager.GetLogger("console");
logger.Info("Trying to start");
const string mutexId = #"Global\{{guid-guid-guid-guid-guid}}";
bool createdNew;
using (var mutex = new Mutex(false, mutexId, out createdNew))
{
var hasHandle = false;
try
{
try
{
hasHandle = mutex.WaitOne(5000, false);
if (!hasHandle)
{
logger.Error("Timeout waiting for exclusive access");
throw new TimeoutException("Timeout waiting for exclusive access");
}
}
catch (AbandonedMutexException)
{
hasHandle = true;
}
// Perform your work here.
PerformWorkHere();
}
finally
{
if (hasHandle)
{
mutex.ReleaseMutex();
}
}
}
}