lock中使用迭代返回yield return是否会释放锁？

项目中遇到一个问题如题，于是做了个小实验，发现在lock中yield return并不会释放该lock，直到整个迭代器完全执行完或者yield break后才会释放lock。

 1 class Program

 2     {

 3         static object mylock = new object();

 4         static long index = 0xff;

 5             

 6         static void Main(string[] args)

 7         {

 8             System.Threading.Thread t1 = new System.Threading.Thread(

 9                 () =>

10                 {

11                     foreach (long l in method1())

12                     {

13                         for (int i = 0; i < 0xff;i++ )

14                             Console.WriteLine("\t" + i.ToString("X2"));

15                         Console.WriteLine(l.ToString("X4"));

16                     }

17                 });

18             t1.IsBackground = true;

19             t1.Start();

20 

21 

22             System.Threading.Thread t2 = new System.Threading.Thread(

23                 () =>

24                 {

25                     for (int i = 0; i < 100; i++)

26                     {

27                         lock (mylock)

28                         {

29                             Console.WriteLine("\t\t\tI'm in the lock!");

30                         }

31                     }

32                 });

33             t2.IsBackground=true;

34             t2.Start();

35 

36 

37             Console.ReadKey();

38         }

39 

40         static IEnumerable<long> method1()

41         {

42             lock (mylock)

43             {

44                 for (long i = 0; i < index; i++)

45                 {

46                     yield return i;

47                 }

48             }

49         }

50     }

运行如下：