c# - 如何使用这个信号量

Question

        List<int> cuis = PersistencyServices.GetListOfAllCui();             
        ResourceLock = new Semaphore(3, 5);


        foreach (var cui in cuis)
        {

            Thread workThread = new Thread(new ParameterizedThreadStart(Worker));

            workThread.Start(cui);

        }

    }
    public static void Worker(object cui)
    {

        ResourceLock.WaitOne();

        Debug.WriteLine(String.Format("Thread for cui {0} in", cui));

        Thread.Sleep(5000);
        ResourceLock.Release();
    }

此代码一次只允许 3 个线程处于临界区。但问题是，因为列表包含超过 100 万条记录，所以我得到了 OutOfMemoryException。我认为这是因为即使信号量只允许3个线程进入临界区，但是创建了100万个线程等待信号量。我应该如何更改我的代码以防止这种情况发生？请帮忙

Answer 1

你真的不想要一百万个线程。不清楚你在做什么，但它看起来可能 Parallel.ForEach(...) 会在这里做你想做的一切，工作量很小理智。

如果你只想强制执行 3 个线程:

Parallel.ForEach(cuis, new ParallelOptions { MaxDegreeOfParallelism = 3 },
        Worker);

与:

public static void Worker(int cui)
{
    Debug.WriteLine(String.Format("Thread for cui {0} in", cui));
    Thread.Sleep(5000);
}

---

如果你真的想使用信号量，使用WaitOne来循环:

foreach (var cui in cuis)
{
    ResourceLock.WaitOne();
    Thread workThread = new Thread(new ParameterizedThreadStart(Worker));

    workThread.Start(cui);

}
...
public static void Worker(object cui)
{
    Debug.WriteLine(String.Format("Thread for cui {0} in", cui));

    Thread.Sleep(5000);
    ResourceLock.Release();
}