A18_深入瞭解多線程

/*
 * 測試線程的“死鎖”，及解決方法
 * 
 * 
 * 
 * **/
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;

namespace A18_IndepthStudyMultitheading
{
    class TestClass
    {
        private int _GameState = 100;
        private object objLock = new object();


        public void ChangeState()
        {
            while (true)
            {
                lock(objLock) //通過lock關鍵字讓多個線程順序訪問公共數據。
                {
                    ChangeMyState();
                }
                
            }
        }


        private void ChangeMyState()
        {

            ++_GameState;
            if (_GameState == 100) //
            {
                Console.WriteLine("_GameState == 100,本語句一般情況下不會輸出");
            }
            _GameState = 100; //多線程在爭搶資源時有可能會因爲這條語句而得到_GameState的值爲100，從而使上面的判斷成立
        }
    }
}

/*
 * 進一步演示“死鎖”示例
 * 
 * 
 * **/
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;


namespace A18_IndepthStudyMultitheading
{
    
    class TestClass2
    {
        private int _Num = 0;
        private object objLock = new object(); //設置一個“所”


        public void Add()
        {
            while (true)
            {
                lock (objLock)
                {
                    _Num++;
                    Thread.Sleep(1000);
                    Console.WriteLine(Thread.CurrentThread.Name + ": " + _Num); 
                }
            }
        }
    }
}

/*
 * 多線程的“死鎖”與“同步”問題
 * 死鎖：多個線程爭搶公共資源造成的異常情況
 * 使用lock關鍵字讓多個線程順序訪問公共資源，暨線程的“同步”
 * 
 * **/
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using System.Threading;

namespace A18_IndepthStudyMultitheading
{
    class Demo1
    {
        public void Test1()
        {
            Console.WriteLine("測試與實驗多線程的死鎖問題1");
            TestClass testObj = new TestClass();

            Thread t1 = new Thread(testObj.ChangeState);
            t1.Start();

            Thread t2 = new Thread(testObj.ChangeState);
            t2.Start();

        }

        public void Test2()
        {
            Console.WriteLine("測試與實驗多線程的死鎖問題2");
            TestClass2 testObj = new TestClass2();

            Thread t1 = new Thread(testObj.Add);
            t1.Name = "TA";
            t1.Start();

            Thread t2 = new Thread(testObj.Add);
            t2.Name = "TB";
            t2.Start();

        }

        static void Main1(string[] args)
        {
            Demo1 obj = new Demo1();
            //obj.Test1();
            obj.Test2();
        }
    }
}

/*
 * 線程池 和 任務
 * 線城池中的線程都是後臺線程
 * 線城池中的線程不能更改爲前臺線程，也不能更改優先級
 * 
 * 
 * **/
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using System.Threading;


namespace A18_IndepthStudyMultitheading
{
    class Demo2
    {

        public void ThreaMethod1(object para)
        {
            Console.WriteLine("開始下載（當前線程編號）：" + Thread.CurrentThread.ManagedThreadId);
            Thread.Sleep(3000);
            Console.WriteLine("下載完畢！！！");
        }


        public void ThreadMethod2()
        {
            Console.WriteLine("開始下載");
            Thread.Sleep(2000);
            Console.WriteLine("下載完畢！！");
        }

        //線城池的使用
        public void Test1()
        {
            //使用線程池
            ThreadPool.QueueUserWorkItem(ThreaMethod1, 123);
            ThreadPool.QueueUserWorkItem(ThreaMethod1, 123);
            ThreadPool.QueueUserWorkItem(ThreaMethod1, 123);
            ThreadPool.QueueUserWorkItem(ThreaMethod1, 123);
            ThreadPool.QueueUserWorkItem(ThreaMethod1, 123);
            ThreadPool.QueueUserWorkItem(ThreaMethod1, 123);
            ThreadPool.QueueUserWorkItem(ThreaMethod1, 123);
            ThreadPool.QueueUserWorkItem(ThreaMethod1, 123);
            ThreadPool.QueueUserWorkItem(ThreaMethod1, 123);
            ThreadPool.QueueUserWorkItem(ThreaMethod1, 123);
            ThreadPool.QueueUserWorkItem(ThreaMethod1, 123);
            ThreadPool.QueueUserWorkItem(ThreaMethod1, 123);
            ThreadPool.QueueUserWorkItem(ThreaMethod1, 123);
            ThreadPool.QueueUserWorkItem(ThreaMethod1, 123);

            Console.ReadLine();
        }

        //任務的使用
        public void Test2()
        {
            Task t = new Task(ThreadMethod2);
            t.Start();
            Console.ReadLine();
        }

        //任務工廠的使用
        public void Test3()
        {
            TaskFactory ft = new TaskFactory();
            Task t = ft.StartNew(ThreadMethod2);
            Console.ReadLine();
        }


        static void Main(string[] args)
        {
            Demo2 obj = new Demo2();
            //obj.Test1();
            obj.Test2();
        }
    }
}