[Mono-dev] Mutex Bug
Edward Ned Harvey (mono)
edward.harvey.mono at clevertrove.com
Wed Jul 2 19:31:57 UTC 2014
Before anything else ... Can anybody recommend a way to do interprocess mutex?
I would like to confirm this is a bug before I go create a bug report in bugzilla. Can anybody please confirm both (a) you get the same behavior, and (b) it's not correct behavior?
I want to make this observation as well: The class in question is System.Threading.Mutex. But on the mono class status pages, there seems to be no System.Threading.Mutex. So that sounds a little suspicious to me, but maybe it's ok? Or maybe I'm overlooking it somehow?
Here is some sample source code:
static string mutexName;
const int numThreads = 5;
static Thread allThreads = new Thread[numThreads];
public static void Main(string args)
mutexName = @"Global\mutex-test-erihjbnkjvwiuehrnkjcxvjhwehiu";
for (int i=0; i<numThreads; i++)
allThreads[i] = new Thread(new ThreadStart(DoSomething));
allThreads[i].Name = "Thread #" + i.ToString();
static void DoSomething()
System.Console.Error.WriteLine(Thread.CurrentThread.Name + " starting...");
using (var myMutex = new Mutex(false,mutexName))
System.Console.Error.WriteLine(Thread.CurrentThread.Name + " running...");
System.Console.Error.WriteLine(Thread.CurrentThread.Name + " finished...");
When run in windows .NET, you launch several processes that each run the above code, and the Mutex will only allow one process to enter at a time.
When run in Mono, a single process obeys the mutex correctly, but multiple processes that are launched concurrently, each have an apparently private mutex, because each process will allow a single thread to enter the mutex concurrently.
In other words, the mutex *should* provide synchronization across multiple processes, but it doesn't. Instead, it only provides synchronization across multiple threads within a single process.
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