线程池与BlockingCollection(Thread Pool with BlockingCollection)

 问题：有多个线程访问资源。 我需要限制他们的数量为恒定的MaxThreads 。 无法进入线程池的线程应该收到错误消息。 
 
 解决方案：我开始在下面的算法中使用BlockingCollection<string> pool ，但我看到BlockingCollection需要调用CompleteAdding ，这是我无法做到的，因为我总是得到传入的线程（我在下面的示例中硬编码为10）调试目的），请考虑Web请求。 
 
public class MyTest {

    private const int MaxThreads = 3;

    private BlockingCollection<string> pool;

    public MyTest() { 
        pool = new BlockingCollection<string>(MaxThreads);
    }

    public void Go() {
        var addSuccess = this.pool.TryAdd(string.Format("thread ID#{0}", Thread.CurrentThread.ManagedThreadId));
        if (!addSuccess) Console.WriteLine(string.Format("thread ID#{0}", Thread.CurrentThread.ManagedThreadId));
        Console.WriteLine(string.Format("Adding thread ID#{0}", Thread.CurrentThread.ManagedThreadId));
        Console.WriteLine(string.Format("Pool size: {0}", pool.Count));

        // simulate work
        Thread.Sleep(1000);

        Console.WriteLine("Thread ID#{0} " + Thread.CurrentThread.ManagedThreadId + " is done doing work.");
        string val;
        var takeSuccess = this.pool.TryTake(out val);
        if (!takeSuccess) Console.WriteLine(string.Format("Failed to take out thread ID#{0}", Thread.CurrentThread.ManagedThreadId));
        Console.WriteLine("Taking out " + val);

        Console.WriteLine(string.Format("Pool size: {0}", pool.Count));
        Console.WriteLine(Environment.NewLine);
    }
}

static void Main()
{
    var t = new MyTest();

    Parallel.For(0, 10, x => t.Go());
}
 
 关于如何更好地实现这一点的任何想法？ 
 
 谢谢！ 
 
 PS多线程新手在这里，如果你有任何阅读材料的建议，我将不胜感激他们。 
 
 LE：基于我得到的答案，我能够使用这种算法实现期望的行为： 
 
public class MyTest {

    private const int MaxThreads = 3;

    private SemaphoreSlim semaphore;

    public MyTest() { 
        semaphore = new SemaphoreSlim(MaxThreads, MaxThreads);
    }

    public void Go() {

        Console.WriteLine(string.Format("In comes thread ID#{0}", Thread.CurrentThread.ManagedThreadId));
        semaphore.Wait();

        try {

        Console.WriteLine(string.Format("Serving thread ID#{0}", Thread.CurrentThread.ManagedThreadId));
        // simulate work
        Thread.Sleep(1000);
        Console.WriteLine(string.Format("Out goes thread ID#{0}", Thread.CurrentThread.ManagedThreadId));

        }

        finally {
            semaphore.Release();
        }

    }
}

static void Main()
{
    var t = new MyTest();

    Parallel.For(0, 10, x=> t.Go());
}

Problem: There are multiple threads accessing a resource. I need to limit their number to a constant MaxThreads. Threads who cannot enter the thread pool should get an error message.
 
Solution: I started using a BlockingCollection<string> pool in the algorithm below, but I see that BlockingCollection requires a call to CompleteAdding, which I can't do, because I always get incoming threads (I hardcoded to 10 in the example below for debugging purposes), think web requests.
 
public class MyTest {

    private const int MaxThreads = 3;

    private BlockingCollection<string> pool;

    public MyTest() { 
        pool = new BlockingCollection<string>(MaxThreads);
    }

    public void Go() {
        var addSuccess = this.pool.TryAdd(string.Format("thread ID#{0}", Thread.CurrentThread.ManagedThreadId));
        if (!addSuccess) Console.WriteLine(string.Format("thread ID#{0}", Thread.CurrentThread.ManagedThreadId));
        Console.WriteLine(string.Format("Adding thread ID#{0}", Thread.CurrentThread.ManagedThreadId));
        Console.WriteLine(string.Format("Pool size: {0}", pool.Count));

        // simulate work
        Thread.Sleep(1000);

        Console.WriteLine("Thread ID#{0} " + Thread.CurrentThread.ManagedThreadId + " is done doing work.");
        string val;
        var takeSuccess = this.pool.TryTake(out val);
        if (!takeSuccess) Console.WriteLine(string.Format("Failed to take out thread ID#{0}", Thread.CurrentThread.ManagedThreadId));
        Console.WriteLine("Taking out " + val);

        Console.WriteLine(string.Format("Pool size: {0}", pool.Count));
        Console.WriteLine(Environment.NewLine);
    }
}

static void Main()
{
    var t = new MyTest();

    Parallel.For(0, 10, x => t.Go());
}
 
Any ideas on how I can better achieve this?
 
Thanks!
 
P.S. Multi-threading newbie here, if you have any suggestions for reading materials, I would greatly appreciate them.
 
LE: Based on the answers I got, I was able to achieve the desired behavior using this algorithm:
 
public class MyTest {

    private const int MaxThreads = 3;

    private SemaphoreSlim semaphore;

    public MyTest() { 
        semaphore = new SemaphoreSlim(MaxThreads, MaxThreads);
    }

    public void Go() {

        Console.WriteLine(string.Format("In comes thread ID#{0}", Thread.CurrentThread.ManagedThreadId));
        semaphore.Wait();

        try {

        Console.WriteLine(string.Format("Serving thread ID#{0}", Thread.CurrentThread.ManagedThreadId));
        // simulate work
        Thread.Sleep(1000);
        Console.WriteLine(string.Format("Out goes thread ID#{0}", Thread.CurrentThread.ManagedThreadId));

        }

        finally {
            semaphore.Release();
        }

    }
}

static void Main()
{
    var t = new MyTest();

    Parallel.For(0, 10, x=> t.Go());
}

原文：https://stackoverflow.com/questions/26099488