保证集合的线程安全问题

确保集合的线程安全。在开启多线程操作集合的时候，很容易对集合进行增删改查，这样子，集合的访问情况就会变化。

AutoResetEvent：reset()方法.将线程设置为非终止状态，导致线程阻止；set()方法.将线程设置为终止状态，允许一个或多个等待线程继续。两者设置成功均返回true，不成功返回false.

　　　　　　　　waitOn():阻止当前线程，直到接收到信号。收到set信号后，只执行一个线程，其他继续等待。

 

 static List<Person> personList = new List<Person>()
            {
                new Person{Name = "Samliy",Age = 29},
                new Person{Name = "Jimmy",Age = 31},
                new Person{Name = "Machial",Age = 28}
            };

        static AutoResetEvent auto = new AutoResetEvent(false);
        static void Main(string[] args)
        {
            Console.WriteLine("Hello World!");
            Thread thread01 = new Thread(() =>
            {
                auto.WaitOne();
                //foreach (var a in personList)
                //{
                //    Console.WriteLine(a.ToString());
                //    Thread.Sleep(1000);
                //}
　　　　　　　　　　//这里如果换成for循环，则不会报错，如果用foreach则会报错，因为集合修改，foreach会有版本号的判断导致无法遍历

                for (int i = 0; i < personList.Count; i++)
                {
                    Console.WriteLine(personList[i].ToString());
                    Thread.Sleep(1000);
                }
            });
            thread01.Start();

            Thread thread02 = new Thread(() =>
            {
                auto.Set();
                Thread.Sleep(1000);
                personList.RemoveAt(2);

            });
            thread02.Start();
        }

 

在泛型集合出现之前，非泛型集合一般会采用SyncRoot属性，要保证非泛型集合的线程安全，就得锁住这个属性来实现

但是泛型集合是没有这个属性的，要通过创建一个锁定对象来完成同步任务。

 

class Program
    {
        static List<Person> personList = new List<Person>()
            {
                new Person{Name = "Samliy",Age = 29},
                new Person{Name = "Jimmy",Age = 31},
                new Person{Name = "Machial",Age = 28}
            };static AutoResetEvent auto = new AutoResetEvent(false);

        static Object sync = new object();
        static void Main(string[] args)
        {
            //Object sync = new object();
            Console.WriteLine("Hello World!");
            Thread thread01 = new Thread(() =>
            {
                auto.WaitOne();
                lock (sync)
                {
                    Console.WriteLine("先打印数据");
                    foreach (var a in personArrayList)
                    {
                        Console.WriteLine(a.ToString());
                        Thread.Sleep(1000);
                    }
                }
                //for (int i = 0; i < personList.Count; i++)
                //{
                //    Console.WriteLine(personList[i].ToString());
                //    Thread.Sleep(1000);
                //}
            });
            thread01.Start();

            Thread thread02 = new Thread(() =>
            {
                auto.Set();
                lock (sync)
                {
                    Console.WriteLine("先删除数据");
                    Thread.Sleep(1000);
                    personArrayList.RemoveAt(2);
                }

            });
            thread02.Start();
        }
    }

 

使用非泛型的线程锁：
 非泛型的集合，提供SyncRoot的锁方法，可以锁住集合只让一个线程操作。

class Program
    {
        static List<Person> personList = new List<Person>()
            {
                new Person{Name = "Samliy",Age = 29},
                new Person{Name = "Jimmy",Age = 31},
                new Person{Name = "Machial",Age = 28}
            };

        static ArrayList personArrayList = new ArrayList()
        {
            new Person{Name = "Samliy",Age = 29},
            new Person{Name = "Jimmy",Age = 31},
            new Person{Name = "Machial",Age = 28}
        };

        static AutoResetEvent auto = new AutoResetEvent(false);

        //static Object sync = new object();
        static void Main(string[] args)
        {
            //Object sync = new object();
            Console.WriteLine("Hello World!");
            Thread thread01 = new Thread(() =>
            {
                auto.WaitOne();
                lock (personArrayList.SyncRoot)
                {
                    Console.WriteLine("先打印数据");
                    foreach (var a in personArrayList)
                    {
                        Console.WriteLine(a.ToString());
                        Thread.Sleep(1000);
                    }
                }
                //for (int i = 0; i < personList.Count; i++)
                //{
                //    Console.WriteLine(personList[i].ToString());
                //    Thread.Sleep(1000);
                //}
            });
            thread01.Start();

            Thread thread02 = new Thread(() =>
            {
                auto.Set();
                lock (personArrayList.SyncRoot)
                {
                    Console.WriteLine("先删除数据");
                    Thread.Sleep(1000);
                    personArrayList.RemoveAt(2);
                }

            });
            thread02.Start();
        }
    }