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多线程的锁定,该怎么解决

发布时间: 2012-01-21 21:31:43 作者: rapoo

多线程的锁定
我做了一个小测试是关于多线程的,但是结果与我期望的不同。
using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;

namespace ThreadTest
{

public class LockCodeArea
{
private int count = 10;
public void ReduceCount()
{
while (true)
{
lock (this)
{
Console.WriteLine("Current Count:{0}", count);
Console.WriteLine("Current thread HashCode is :{0}", Thread.CurrentThread.GetHashCode());
Thread.Sleep(100);
--count;
if (count > 0)
continue;
else
break;
}
}
}
}
class Program
{
static void Main(string[] args)
{
LockCodeArea testClass = new LockCodeArea();
Thread firsThread = new Thread(new ThreadStart(testClass.ReduceCount));
Thread secondThread = new Thread(new ThreadStart(testClass.ReduceCount));
Console.WriteLine("Main HashCode is :{0}", Thread.CurrentThread.GetHashCode());
Console.WriteLine("First thread Hashcode is :{0}",firsThread.GetHashCode());
Console.WriteLine("Second thread HashCode is :{0}", secondThread.GetHashCode());
firsThread.Start();
secondThread.Start();
if (!firsThread.IsAlive)
Thread.Sleep(1000);
Console.WriteLine("Press Any Key to Continue!");
Console.WriteLine("Main HashCode is :{0}", Thread.CurrentThread.GetHashCode());
Console.ReadLine();

}
}
}
本来是希望使用Lock之后,只存在要么firstThread减数,要么secondThread减数,为什么会有firstThread和secondThead
交替减数的情况。我已经使用Lock锁定代码区了。???各位帮帮忙呀。

[解决办法]
注意,lock锁定的块同一时间只有一个线程能访问,你目前的代码锁定的是while内的代码。也就是说有2个线程都到达了循环内,一个现成continue的时候另一个线程乘机执行Console.WriteLine....
如果要同一时间只有1个线程能执行整个循环,就要把整个循环(10次)都锁住,也就是说:

C# code
 public void ReduceCount()        {            lock (this)            {                while (true)                {                    Console.WriteLine("Current Count:{0}", count);                    Console.WriteLine("Current thread HashCode is :{0}", Thread.CurrentThread.GetHashCode());                    Thread.Sleep(100);                    --count;                    if (count > 0)                        continue;                    else                        break;                }            }        } 

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