C# Thread.Join()

Thread.Join() 官网解释如下：

https://docs.microsoft.com/zh-cn/dotnet/api/system.threading.thread.join?view=netframework-4.8

在此实例表示的线程终止前，阻止调用线程。

如下代码，thread1 是最先运行，但是由于执行 thread2.join() 阻塞了线程，所以必须等到 thread2 线程执行完成后，才会继续执行 thread1。

也就是：前线程CurThread将被阻塞，直到CalleeThread线程完成后CurThread 刚刚CalleeThread.Join() 的后续代码才继续往下执行

using System;
using System.Threading;

public class Example
{
   static Thread thread1, thread2;
   
   public static void Main()
   {
      thread1 = new Thread(ThreadProc);
      thread1.Name = "Thread1";
      thread1.Start();
      
      thread2 = new Thread(ThreadProc);
      thread2.Name = "Thread2";
      thread2.Start();   
   }

   private static void ThreadProc()
   {
      Console.WriteLine("
Current thread: {0}", Thread.CurrentThread.Name);
      if (Thread.CurrentThread.Name == "Thread1" && 
          thread2.ThreadState != ThreadState.Unstarted)
         thread2.Join();
      
      Thread.Sleep(4000);
      Console.WriteLine("
Current thread: {0}", Thread.CurrentThread.Name);
      Console.WriteLine("Thread1: {0}", thread1.ThreadState);
      Console.WriteLine("Thread2: {0}
", thread2.ThreadState);
   }
}
// The example displays output like the following:
//       Current thread: Thread1
//       
//       Current thread: Thread2
//       
//       Current thread: Thread2
//       Thread1: WaitSleepJoin
//       Thread2: Running
//       
//       
//       Current thread: Thread1
//       Thread1: Running
//       Thread2: Stopped

有一篇解释的还可以的文章：

https://www.cnblogs.com/slikyn/articles/1525940.html