有时我们lock一段代码或许要根据某个变量的值，值相同则不允许有两个或以上的方法并行运行，我在工作中就遇到了，有100个值，相同的参数值不能并行运行。
还有就是一个被lock的方法递归调用会不会死锁，因为需要lock同一个变量。答案当然是不会死锁。
下面是一个测试demo
class Program
{
private static object a = new object();
private static object b = new object();
private static object c = new object();
private static Hashtable list = Hashtable.Synchronized(new Hashtable()); static void Main(string[] args)
{
//所有i不相等的线程将同步执行并返回结果
new Thread(new ParameterizedThreadStart(delegate(object obj) {
Test(, );
Console.WriteLine("");
})).Start(); new Thread(new ParameterizedThreadStart(delegate(object obj)
{
Test(, );
Console.WriteLine("1+");
})).Start(); //所有i==2的线程将顺序执行
new Thread(new ParameterizedThreadStart(delegate(object obj)
{
Test(, );
Console.WriteLine("");
})).Start(); new Thread(new ParameterizedThreadStart(delegate(object obj)
{
Test(, );
Console.WriteLine("");
})).Start(); new Thread(new ParameterizedThreadStart(delegate(object obj)
{
Test(, );
Console.WriteLine("");
})).Start(); new Thread(new ParameterizedThreadStart(delegate(object obj)
{
Test(, );
Console.WriteLine("");
})).Start(); new Thread(new ParameterizedThreadStart(delegate(object obj)
{
Test(, );
Console.WriteLine("");
})).Start(); //两次lock同一变量不会死锁
new Thread(new ParameterizedThreadStart(delegate(object obj)
{
Test2(, );
Console.WriteLine("");
})).Start(); Console.ReadKey();
} /// <summary>
/// 对于i相同的线程进行阻塞保证不会并行多个
/// </summary>
/// <param name="i"></param>
/// <param name="j"></param>
public static void Test(int i,int j)
{
if (!list.ContainsKey(i))
list.Add(i, DateTime.Now); lock (list[i])
{
Thread.Sleep(j);
}
} //多次lock同一变量测试是否会死锁
public static void Test2(int i, int j, bool isFirstRun = true)
{
if (!list.ContainsKey(i))
list.Add(i, DateTime.Now); lock (list[i])
{
Thread.Sleep(j);
if (isFirstRun)
Test2(i, j, false);
}
}
}
程序输出如下：
+