基本知识，无参数Thread和带参数的Thread
Thread类的参数就是参数指针，可以传入一个无参的函数。
如果要传入带参数的函数，先new一个ParameterizedThreadStart委托实例，带参数的函数名作为它的参数。带参数的函数必须且只能有一个object参数。参考下面的
ConterWithParam(object param)
static int iCnt = ;
static readonly int N = ; static void Main(string[] args)
{
Thread[] thrs = new Thread[N];
for (int i = ; i < N; i++)
{
thrs[i] = new Thread(Counter);
thrs[i].Start();
}
for (int i = ; i < N; i++)
{
thrs[i].Join();
}
Console.WriteLine(iCnt); iCnt = ; ParameterizedThreadStart[] thrsp = new ParameterizedThreadStart[N];
object param = ;
for (int i = ; i < N; i++)
{
thrsp[i] = new ParameterizedThreadStart(ConterWithParam);
thrs[i] = new Thread(thrsp[i]);
thrs[i].Start(param);
}
for (int i = ; i < N; i++)
{
//当NewThread调用Join方法的时候，MainThread就被停止执行，直到NewThread线程执行完毕
thrs[i].Join();
}
Console.WriteLine(iCnt);
} static void Counter()
{
Thread.Sleep();
iCnt++;
//Console.WriteLine("finish iCnt++,now iCnt is " + iCnt);
} static void ConterWithParam(object param)
{
Thread.Sleep();
int i = (int)param;
iCnt += i;
//Console.WriteLine("finish iCnt+"+i+",now iCnt is " + iCnt);
}
该例子输出结果
2)互斥信号灯mutex
第一节的结果是不是有点奇怪。明明加了10000次，结果却是9550.
带参数的那个例子，一次加2，加10000次，应该是20000才对。结果却是19678.
这是因为对全局变量的访问iCnt出现了冲突。比如两个线程同时取到了iCnt=0时的值，同时执行了i++，那么iCnt的最后状态肯定是1，而不是会2。为了让iCnt得到正确的值。
我们引入互斥信号灯。
static int iCnt = ;
static readonly int N = ;
static Mutex mut = new Mutex(); static void Main(string[] args)
{
Thread[] thrs = new Thread[N];
for (int i = ; i < N; i++)
{
thrs[i] = new Thread(Counter);
thrs[i].Start();
}
for (int i = ; i < N; i++)
{
thrs[i].Join();
}
Console.WriteLine(iCnt); iCnt = ; ParameterizedThreadStart[] thrsp = new ParameterizedThreadStart[N];
object param = ;
for (int i = ; i < N; i++)
{
thrsp[i] = new ParameterizedThreadStart(ConterWithParam);
thrs[i] = new Thread(thrsp[i]);
thrs[i].Start(param);
}
for (int i = ; i < N; i++)
{
//当NewThread调用Join方法的时候，MainThread就被停止执行，直到NewThread线程执行完毕
thrs[i].Join();
}
Console.WriteLine(iCnt);
} static void Counter()
{
Thread.Sleep();
//锁
mut.WaitOne();
iCnt++;
//释放
mut.ReleaseMutex();
//Console.WriteLine("finish iCnt++,now iCnt is " + iCnt);
} static void ConterWithParam(object param)
{
Thread.Sleep();
//锁住
mut.WaitOne();
int i = (int)param;
iCnt += i;
//释放
mut.ReleaseMutex();
//Console.WriteLine("finish iCnt+"+i+",now iCnt is " + iCnt);
}
本次执行结果
3) 同步信号灯Semaphore
用最经典的生产者-消费者来解释。
static Semaphore sem = new Semaphore(, );
static Semaphore sem2 = new Semaphore(, ); static void Main(string[] args)
{
Console.WriteLine("消费者等生产者生产一个item");
Thread thConsumer = new Thread(Consume);
thConsumer.Start();
Thread thProductor = new Thread(Product);
thProductor.Start(); thConsumer.Join();
thProductor.Join();
Console.WriteLine("............................."); Console.WriteLine("多并发的例子.....");
for (int i = ; i < ; i++)
{
Thread t1 = new Thread(Consume2);
t1.Start();
Thread t2 = new Thread(Product2);
t2.Start();
}//end for } static void Product()
{
Thread.Sleep();
Console.WriteLine("Product an item...");
sem.Release();
} static void Consume()
{
Thread.Sleep();
Console.WriteLine("Consumer is waiting an item...");
sem.WaitOne();
Console.WriteLine("Consumer get an item...");
} static void Product2()
{
Thread.Sleep();
Console.WriteLine("Product an item...");
sem2.Release();
} static void Consume2()
{
Thread.Sleep();
Console.WriteLine("Consumer is waiting an item...");
sem2.WaitOne();
Console.WriteLine("Consumer get an item...");
}