下面的代码示例说明增加和减少整数值的线程安全方式。SafeInstanceCount 始终为 0。但是 UnsafeInstanceCount 不一定为 0，因为在增加和减少计数之间会出现争用条件。此效果在多处理器计算机上尤其明显。

using System;
using System.Threading;

class Test
{
    static void Main()
    {
        Thread thread1 = new Thread(new ThreadStart(ThreadMethod));
        Thread thread2 = new Thread(new ThreadStart(ThreadMethod));
        thread1.Start();
        thread2.Start();
        thread1.Join();
        thread2.Join();

        // Have the garbage collector run the finalizer for each
        // instance of CountClass and wait for it to finish.
        GC.Collect();
        GC.WaitForPendingFinalizers();

        Console.WriteLine("UnsafeInstanceCount: {0}" +
            "\nSafeCountInstances: {1}",
            CountClass.UnsafeInstanceCount.ToString(),
            CountClass.SafeInstanceCount.ToString());
    }

    static void ThreadMethod()
    {
        CountClass cClass;

        // Create 100,000 instances of CountClass.
        for(int i = 0; i < 100000; i++)
        {
            cClass = new CountClass();
        }
    }
}

class CountClass
{
    static int unsafeInstanceCount = 0;
    static int   safeInstanceCount = 0;

    static public int UnsafeInstanceCount
    {
        get {return unsafeInstanceCount;}
    }

    static public int SafeInstanceCount
    {
        get {return safeInstanceCount;}
    }

    public CountClass()
    {
        unsafeInstanceCount++;
        Interlocked.Increment(ref safeInstanceCount);
    }

    ~CountClass()
    {
        unsafeInstanceCount--;
        Interlocked.Decrement(ref safeInstanceCount);
    }
}