[Mono-bugs] [Bug 49824][Nor] New - Threading.SyncronizationException thrown on calling Monitor.Exit on an object that has not been locked.

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Changed by bmaurer at users.sf.net.

http://bugzilla.ximian.com/show_bug.cgi?id=49824

--- shadow/49824	2005-06-24 01:52:14.000000000 -0400
+++ shadow/49824.tmp.19948	2005-06-24 01:52:14.000000000 -0400
@@ -0,0 +1,133 @@
+Bug#: 49824
+Product: Mono: Runtime
+Version: unspecified
+OS: Red Hat 9.0
+OS Details: Standard Install
+Status: NEW   
+Resolution: 
+Severity: Unknown
+Priority: Normal
+Component: misc
+AssignedTo: bmaurer at users.sf.net                            
+ReportedBy: gileslforster at yahoo.co.uk               
+QAContact: mono-bugs at ximian.com
+TargetMilestone: ---
+URL: 
+Cc: 
+Summary: Threading.SyncronizationException thrown on calling Monitor.Exit on an object that has not been locked.
+
+Please fill in this template when reporting a bug, unless you know what 
+you are doing.
+Description of Problem:
+
+Steps to reproduce the problem:
+
+Bellow a simple console application calling Monitor.Exit(obj) on an 
+object to which Monitor.Enter(obj) has not been called.
+
+using System;
+using System.Threading;
+
+namespace ConsoleApplication
+{
+	class Class1
+	{
+		[STAThread]
+		static void Main(string[] args)
+		{
+			Class1 x = new Class1();
+
+			Monitor.Exit(x);
+
+			Console.WriteLine("All done.");
+		}
+	}
+}
+
+Actual Results:
+
+[giles at Linux-02 Mono]$ mono ConsoleApplication.exe
+
+ 
+
+Unhandled Exception: System.Threading.SynchronizationLockException: Not 
+locked
+
+in (unmanaged) /usr/lib/libmono.so.0(mono_raise_exception+0x20) 
+[0x400aa8e9]
+
+in (unmanaged) /usr/lib/libmono.so.0(mono_monitor_exit+0x3b) [0x400c387d]
+
+in (unmanaged) /usr/lib/libmono.so.0 [0x400c3939]
+
+in <0x0003b> System.Threading.Monitor:Exit (object)
+
+in <0x00036> ConsoleApplication.Class1:Main (string[])
+
+
+Expected Results:
+
+[giles at Linux-02 Mono]$ mono ConsoleApplication.exe
+All done.
+[giles at Linux-02 Mono]$
+
+
+How often does this happen? 
+
+Always.
+
+Additional Information:
+
+Under .NET 1.1 on Windows the default behaviour is to ignore the fact 
+that Enter() has not been called if calling Exit() on an unlocked object 
+for the current thread. On Mono it throws a SynchronizationLockException, 
+leading to incompatible code. Not sure what the ECMA standard says but 
+don't know where to look.
+
+Thanks,
+
+Giles
+
+------- Additional Comments From dick at ximian.com  2003-10-20 11:12 -------
+Looks like the ms Monitor implementation is rather buggy.
+
+using System;
+using System.Threading;
+
+namespace ConsoleApplication
+{
+        class Class1
+        {
+                static Class1 x;
+
+                static void OtherThread()
+                {
+                        Monitor.Exit(x);
+                        Console.WriteLine("Passed x Exit");
+                }
+
+                [STAThread]
+                static void Main(string[] args)
+                {
+                        x = new Class1();
+                        Monitor.Enter(x);
+                        Thread thr=new Thread(new
+ThreadStart(Class1.OtherThread));
+                        thr.Start();
+                        thr.Join();
+
+                        Console.WriteLine("All done.");
+                }
+        }
+}
+
+prints both WriteLines for me, ms runtime 1.1.
+
+Reading the Monitor class documentation again, I suppose it could be
+argued that "The current thread does not own the lock for the
+specified object" could be read so as to not throw
+SynchronizationLockException when the object is not locked at all, but
+unless my test above is faulty, it isn't thrown even when another
+thread _does_ own the lock.  (Changing the Monitor.Exit(x) into a
+Monitor.Enter(x) does deadlock as expected though.)
+