C# - 循环不会停止(每次迭代都会启动新任务)

时间:2016-03-27 23:16:19

标签: c# multithreading for-loop task-parallel-library

所以我对下面的餐饮哲学家的问题有一个基本的解决方案:

using System;
using System.Threading.Tasks;

namespace Conductor
{
    class Program
    {
        private static object _locker = new object();

        static void Main(string[] args)
        { 
            object[] sticks = {new object(),
                               new object(),
                               new object(),
                               new object(),
                               new object()};

            for (int i = 0; i<5; i++)
            {
                int next = (i + 1) % 5;
                Task.Factory.StartNew(() => Eat(sticks[i], sticks[next], i)); 
            }
        }

        static void Eat(object _leftChopstick, object _rightChopstick, int i)
        {
            lock (_locker)
            {
                lock (_leftChopstick)
                {
                    lock (_rightChopstick)
                    {
                        Console.WriteLine("Eating" + i);
                    }
                }
            }
        }
    }
}

虽然它可能不是最有效的解决方案,但它会在&#34; StartNew&#34;上引发IndexOutOfRange异常。当我被设置为5时调用。我无法弄清楚如何使用任务工厂以某种方式使我的程序忽略for循环条件。

如果我运行此代码,那很好:

using System;
using System.Threading.Tasks;

namespace Conductor
{
    class Program
    {
        private static object _locker = new object();

        static void Main(string[] args)
        { 
            object[] sticks = { new object(),
                               new object(),
                               new object(),
                               new object(),
                               new object()};

            int i = 0;
            Task.Factory.StartNew(() => Eat(sticks[i], sticks[i + 1], i));
            Task.Factory.StartNew(() => Eat(sticks[i+1], sticks[i + 2], i + 1));
            Task.Factory.StartNew(() => Eat(sticks[i+2], sticks[i + 3], i + 2));
            Task.Factory.StartNew(() => Eat(sticks[i+3], sticks[i + 4], i + 3));
            Task.Factory.StartNew(() => Eat(sticks[i + 4], sticks[0], i + 4));
            Console.ReadLine();
        }

        static void Eat(object _leftChopstick, object _rightChopstick, int i)
        {
            lock (_locker)
            {
                lock (_leftChopstick)
                {
                    lock (_rightChopstick)
                    {
                        Console.WriteLine("Eating" + i);
                    }
                }
            }
        }
    }
}

另外,如果我通过循环调试,我得到相同的异常。

对此的任何帮助将不胜感激。对不起,如果它太基本或者我的代码中有一些微不足道的缺陷我就错过了。感谢。

1 个答案:

答案 0 :(得分:0)

for (int i = 0; i < 5; i++)
            {
                int j = i;
                int next = (i + 1) % 5;
                Task.Factory.StartNew(() => Eat(sticks[j], sticks[next], j));
            }