public class BI 
    {
        static object Locker = new object();
        public BI() 
        {
 
        }
        public double Sin()
        {
            lock(Locker)
            {
                return Math.Sin(12.3);
            }
        }
    }

.method public hidebysig 
	instance float64 Sin () cil managed 
{
	// Method begins at RVA 0x2484
	// Code size 55 (0x37)
	.maxstack 2
	.locals init (
		[0] bool '<>s__LockTaken0',
		[1] float64 CS$1$0000,
		[2] object CS$2$0001,
		[3] bool CS$4$0002
	)

	IL_0000: nop
	IL_0001: ldc.i4.0
	IL_0002: stloc.0
	.try
	{
		IL_0003: ldsfld object Test.BI::Locker
		IL_0008: dup
		IL_0009: stloc.2
		IL_000a: ldloca.s '<>s__LockTaken0'
		IL_000c: call void [mscorlib]System.Threading.Monitor::Enter(object, bool&)
		IL_0011: nop
		IL_0012: nop
		IL_0013: ldc.r8 12.3
		IL_001c: call float64 [mscorlib]System.Math::Sin(float64)
		IL_0021: stloc.1
		IL_0022: leave.s IL_0034
	} // end .try
	finally
	{
		IL_0024: ldloc.0
		IL_0025: ldc.i4.0
		IL_0026: ceq
		IL_0028: stloc.3
		IL_0029: ldloc.3
		IL_002a: brtrue.s IL_0033

		IL_002c: ldloc.2
		IL_002d: call void [mscorlib]System.Threading.Monitor::Exit(object)
		IL_0032: nop

		IL_0033: endfinally
	} // end handler

	IL_0034: nop
	IL_0035: ldloc.1
	IL_0036: ret
} // end of method BI::Sin