I wonder about thread id. Plz answer me.

Question

Hi, everyone. First of all, I'm so sorry that I can't speak English Well.

I wonder about thread id. Please look at codes below.

using UnityEngine; 
using System.Collections; 
using System.Threading; 

public class TestScript : MonoBehaviour { 

    void Start () { 
          Debug.Log("current thread id: " + Thread.CurrentThread.GetHashCode().ToString()); 
          (new Thread(thread_test)).Start(); 
    } 

    static void thread_test() 
    { 
          Debug.Log("created thread id: " + Thread.CurrentThread.GetHashCode().ToString()); 
    } 
}

And I got the result below with console panel.

current thread id: 1 
created thread id: 1 

I expected the result below.

current thread id: 1 
created thread id: 2 

Why is 'created thread id' 1? Why isn't it 2? Are 'current thread' and 'created thread' the same thread?

Please tell me about that.

Freeloader

Same deal here, still. Utiny and/or Mono seem to be playing games with us regarding thread ids. I'm positive I'm on a different thread when I call this, yet I get a 1 too always no matter what. WTF??

– Rosauraroscius

Seems I posted as a comment instead of an answer.. Just wanted to say my problem went away the moment I left the editor. It seems this behaviour only occurs inside the editor, not in a build. Kinda screwed for testing purposes, fortunately it's a non-issue for me now..

– Rosauraroscius

Answer 1

You probably want Thread.CurrentThread.ManagedThreadId instead

GetHashCode isn't guaranteed to be unique

Coaming

Thank you very much for your answer. But, I changed my codes with Thread.CurrentThread.ManagedThreadId instead GetHashCode. And I got the same result. I don't know why yet.

– Freeloader

I'm seeing this, too. Even when I know I've got a second thread, Thread.CurrentThread.ManagedThreadId is returning 1, same as the first thread. Yet in the second thread, Unity then proceeds to bark at me if I so much as compare a MonoBehaviour reference to null. What's the deal? How can we tell when we're on the main thread, if Thread.CurrentThread.ManagedThreadId always returns 1?

– Cleres

Answer 2

Yeah, I found the same issue. My work around it was to store the current thread object itself (instead of the id), and to compare the references, as below.

object.ReferenceEquals(System.Threading.Thread.CurrentThread, mainThreadObject)

I also check mainThreadObject.IsAlive, but it always is. Hope it helps.

Pathan

That seems like a good solution. If you're only storing a reference to the main thread, there are no leaks to worry about, as that one is never going to go away anyway. I like it!

– Cleres