Question

下面的代码中这个ThreadName和LocalName有什么区别？它们都是ThreadLocal吗？

// Thread-Local variable that yields a name for a thread
ThreadLocal<string> ThreadName = new ThreadLocal<string>(() =>
{
    return "Thread" + Thread.CurrentThread.ManagedThreadId;
});

// Action that prints out ThreadName for the current thread
Action action = () =>
{
    // If ThreadName.IsValueCreated is true, it means that we are not the 
    // first action to run on this thread. 
    bool repeat = ThreadName.IsValueCreated;
    String LocalName = "Thread" + Thread.CurrentThread.ManagedThreadId;
    System.Diagnostics.Debug.WriteLine("ThreadName = {0} {1} {2}", ThreadName.Value, repeat ? "(repeat)" : "", LocalName);
};

// Launch eight of them.  On 4 cores or less, you should see some repeat ThreadNames
Parallel.Invoke(action, action, action, action, action, action, action, action);

// Dispose when you are done
ThreadName.Dispose();

Answer 1

LocalName不是线程本地的。它的范围是周围lambda的执行。每次lambda运行时，您将获得一个新值（并且并发运行是独立的）。使用ThreadLocal，您可以获得每个帖子的新值。重复调用ThreadName.Value只会在同一个线程上提供一个值。

在这个例子中，两者都是等价的，因为Thread.ManagedThreadId也是线程局部的。试试Guid.NewGuid()。

Answer 2

有一个线程池。因此，如果一个线程被重用于第二个动作，你将得到＆＃34;重复n＃34;。 LocalName是一个局部变量。

C＃中的ThreadLocal与局部变量

2 个答案: