RX观察问题

Question

我是RX的新手，玩了一些样本，关于控制台的原因有什么想法吗?订阅中的writeLine没有被调用?

var obs = Observable。创建(i =>{

              while(true)
            {
                Thread.Sleep(250);
                i.OnNext(2.0);
            }

            return () => { };
        })        
        .SubscribeOn(Scheduler.TaskPool)   
        .ObserveOn(Scheduler.CurrentThread)
        .Subscribe(i =>
        {
            Console.WriteLine("Inside Subscribe");
        });

如果我去掉

.ObserveOn(Scheduler.CurrentThread) 

line all is fine?

谢谢

Answer 1

正如我提到的，SubscribeOn和ObserveOn不是最好命名的方法;我强烈建议你从头到尾读一遍:

http://blogs.msdn.com/b/rxteam/archive/2009/11/21/observable-context-observable-subscribeon-and-observable-observeon.aspx

基本上，SubscribeOn告诉系统在什么上下文中执行实际的订阅/取消订阅连接，而ObserveOn告诉系统在新值到达源时"执行"什么上下文中。

首先，请允许我稍微调整一下您的示例:

Console.WriteLine("Start Thread ID:{0}", Thread.CurrentThread.ManagedThreadId);
var subscription = Observable.Create<double>(i => 
    {
        Console.WriteLine("Observable thread ID:{0}", Thread.CurrentThread.ManagedThreadId);
        while(true)
        {
            Console.WriteLine("Pushing values from thread {0}", Thread.CurrentThread.ManagedThreadId);
            Thread.Sleep(250);            
            i.OnNext(2.0);
        }
        return () => { };
    })        
    .SubscribeOn(Scheduler.TaskPool)   
    .ObserveOn(Scheduler.CurrentThread)
    .Subscribe(i =>
    {
        Console.WriteLine("Subscribable thread ID:{0}", Thread.CurrentThread.ManagedThreadId);
        Console.WriteLine("Inside Subscribe");
    });    
Console.ReadLine();
subscription.Dispose();

如果你运行这个命令，你会看到如下内容:

Start Thread ID:21
Observable thread ID:23
Pushing values from thread 23
Pushing values from thread 23
Pushing values from thread 23
Pushing values from thread 23

现在让我们交换ObserveOn和SubscribeOn的线程:

.SubscribeOn(Scheduler.CurrentThread)   
.ObserveOn(Scheduler.TaskPool)

现在我们得到:

Start Thread ID:26
Observable thread ID:26
Pushing values from thread 26
Pushing values from thread 26
Subscribable thread ID:27
Inside Subscribe
Pushing values from thread 26
Subscribable thread ID:27
Inside Subscribe
Pushing values from thread 26
Subscribable thread ID:27
Inside Subscribe