C#笔试题之同线程Lock语句递归不会死锁

public void test(int i) 
 { 
  lock(this) 
  { 
   if (i > 10) 
   { 
     i--; 
     test(i); 
   } 
  } 
 }

using System;
using System.Threading;

namespace LockDemo
{
  class Program
  {
    static void Main(string[] args)
    {
      Program p = new Program();
      MyObj obj = new MyObj();
      //第一个线程
      Thread thread1 = new Thread(p.test);
      thread1.Name = "thread1";
      //第一个线程
      Thread thread2 = new Thread(p.test);
      thread2.Name = "thread2";
      //启动线程
      thread1.Start(obj);
      thread2.Start(obj);
      Console.Read();
    }

    public void test(object obj)
    {
      lock (this)
      {
        if (((MyObj)obj).value > 10)
        {
          ((MyObj)obj).value--;
          Console.Write(Thread.CurrentThread.Name + ":");
          Console.WriteLine(((MyObj)obj).value);
          Thread.Sleep(10);
          test(obj);
        }
        else
        {
          Console.WriteLine(Thread.CurrentThread.Name);
        }
      }
    }
  }
  /// <summary>
  /// 将一个值类型封装在一个类中，以便多个线程调用方便
  /// </summary>
  public class MyObj
  {
    public int value;

    public MyObj()
    {
      //将初始值赋为20
      value = 20;
    }
  }
}