为什么Parallel.ForEach()方法计算1加到5结果出错，代码挺简单的

Question

  for (int i = 0; i < 100; i++)
            {
                int[] nums = Enumerable.Range(1, 5).ToArray();
                long total = 0;                Parallel.ForEach<int, long>(nums, () => 0, (member, loopState, subtotal) =>
                {
                    if (member == 2)
                        return 0;                    subtotal += member;                    return subtotal;
                },
                    (x) => Interlocked.Add(ref total, x)
                );                Console.WriteLine(total.ToString());
            }十分困惑，我想1-5，除了2以外，统统相加，我笔算了下，结果应该是13，为什么输出了这么多12？Parallel并行ForEach

Answer 1

不要循环
 long total = 0;
           
                int[] nums = Enumerable.Range(1, 5).ToArray();
                               Parallel.ForEach<int, long>(nums, () => 0, (member, loopState, subtotal) =>
                {
                    if (member == 2)
                        return 0;                    subtotal += member;                    return subtotal;
                },
                    (x) => Interlocked.Add(ref total, x)
                );
                Console.WriteLine(total.ToString());