http://ayende.comAyende @ RahienCopyright (C) Ayende Rahien 2004 - 2021 (c) 202660I got the same behaviour for Environment.FailFast and Process.Kill, i.e. AbandonedMutexException is thrown... I did a little refactoring to the given samples, and guess what , only Environment.Exit executes cleanly using System; using System.Collections.Generic; using System.Text; using System.Diagnostics; using System.Threading; using System.Security; using System.Security.Permissions; namespace ConsoleApplication5 { class Program { static void Main(string[] args) { if (args.Length == 0) return; switch (args[0].ToLower()) { case "kill": Kill(args); break; case "exit": Exit(args); break; case "failfast": FailFast(args); break; default: break; } } static void Kill(string[] args) { if (args.Length != 1) { Mutex m = new Mutex(true, "foo"); m.WaitOne(); Console.WriteLine("Got mutex"); Thread.Sleep(1000000); } else { Process p = Process.Start(typeof(Program).Assembly.Location, "kill b"); Thread.Sleep(2000); p.Kill(); Mutex m = new Mutex(true, "foo"); m.WaitOne(); Console.WriteLine("got it second"); } } static void Exit(string[] args) { if (args.Length != 1) { Mutex m = new Mutex(true, "foo"); m.WaitOne(); Console.WriteLine("Got mutex"); Thread.Sleep(1000); Console.WriteLine("Bye, fast"); Environment.Exit(45); } else { Process p = Process.Start(typeof(Program).Assembly.Location, "exit a"); Thread.Sleep(2000); Mutex m = new Mutex(true, "foo"); m.WaitOne(); Console.WriteLine("got it second"); } } static void FailFast(string[] args) { if (args.Length != 1) { Mutex m = new Mutex(true, "foo"); m.WaitOne(); Console.WriteLine("Got mutex"); Thread.Sleep(1000); Console.WriteLine("Bye, fast"); Environment.FailFast("blah"); } else { Process p = Process.Start(typeof(Program).Assembly.Location, "failfast a"); Thread.Sleep(2000); Mutex m = new Mutex(true, "foo"); m.WaitOne(); Console.WriteLine("got it second"); } } } } http://ayende.com/3169/the-mysterious-life-of-mutexes#comment8http://ayende.com/3169/the-mysterious-life-of-mutexes#comment8Tue, 04 Mar 2008 10:40:29 GMT@Jan: Wow. Weird. What kind of exceptions were you getting? Nice to hear about that though - I'll *attempt* to remember it for the next time this comes up on the newsgroups! http://ayende.com/3169/the-mysterious-life-of-mutexes#comment7http://ayende.com/3169/the-mysterious-life-of-mutexes#comment7Fri, 29 Feb 2008 09:17:25 GMT@ Jon Skeet: The GC.KeepAlive has some weird side effects when using in Console apps (instead of Windows Forms apps). I used it for a Console app for keeping the Mutex around. I got some weird exceptions from time to time when the app was closing down. It needed some WinDbg debugging to figure it out that the Mutex was causing this behavior (only on production machines). A Using statement around the Mutex solved the issue. http://ayende.com/3169/the-mysterious-life-of-mutexes#comment6http://ayende.com/3169/the-mysterious-life-of-mutexes#comment6Thu, 28 Feb 2008 20:31:12 GMTNo problem with that. The issue that I have is that it doesn't throw abandon mutex exception http://ayende.com/3169/the-mysterious-life-of-mutexes#comment5http://ayende.com/3169/the-mysterious-life-of-mutexes#comment5Thu, 28 Feb 2008 18:38:24 GMTThe "Threading in C#" book (http://www.albahari.com/threading/part2.html) says: " A good feature of Mutex is that if the application terminates without ReleaseMutex first being called, the CLR will release the Mutex automatically. " In case anyone is curious, I'm trying to coordinate resource cleanup between an AppDomain that is being terminated and a new AppDomain that is being bought in to replace it. Specifically when ASP.Net detects that the web.config has changed and brings up a new AppDomain to replace the old AppDomain...if the old AppDomain is taking too long to services the old requests and IIS terminates the process while the old AppDomain has the Mutext will the Mutext be properly released so the new AppDomain can aquire it? http://ayende.com/3169/the-mysterious-life-of-mutexes#comment4http://ayende.com/3169/the-mysterious-life-of-mutexes#comment4Thu, 28 Feb 2008 18:35:28 GMTI should have said the potential workarounds to avoid the finalizer: 1) Use a "using" statement with the mutex, so the lifetime is clear 2) Use GC.KeepAlive 3) Use a static variable Personally I'm a fan of approach 1, not that I use Mutex much at all in practice. I don't know what effect that would have in your scenarios though - I've no idea whether finally blocks get executed when a process is being killed. http://ayende.com/3169/the-mysterious-life-of-mutexes#comment3http://ayende.com/3169/the-mysterious-life-of-mutexes#comment3Thu, 28 Feb 2008 16:29:30 GMTHaven't check, so that might be. I don't think that this is the right behavior, though http://ayende.com/3169/the-mysterious-life-of-mutexes#comment2http://ayende.com/3169/the-mysterious-life-of-mutexes#comment2Thu, 28 Feb 2008 16:24:47 GMTI can't say I've looked closely enough for sure, but is it possible that you're running into the issue where the Mutex finalizer releases the mutex for you? That trips up a lot of people, very often. I'm too sleepy to check for sure though :) http://ayende.com/3169/the-mysterious-life-of-mutexes#comment1http://ayende.com/3169/the-mysterious-life-of-mutexes#comment1Thu, 28 Feb 2008 16:22:11 GMT