methodimplmethodimploptions.Synchronized同步不同的实例，尽管不应同步

Question

）。我创建了两个实例，运行他们的同步方法，并观察到这些对象相互同步的行为。我不明白为什么会发生这种情况。也许有人遇到了这一点，可以解释吗？

using System.Runtime.CompilerServices;
using Xunit;

public class ThreadsFeaturesUnitDemos
{
  [Fact]
  public void SynchronizedObjects()
  {
    var obj1 = new SynchronizedMethodClass();
    var obj2 = new SynchronizedMethodClass();
    var obj1HashCode = 0;
    var obj2HashCode = 0;
    var chars = string.Empty;
    const string expectedChars1 = "AAAAABBBBBCCCCCDDDDD";
    const string expectedChars2 = "11111222223333344444";

    var d = 'A' - '1';
    for (char c = 'A'; c <= 'D'; c++)
    {
      obj1.Count(ref chars, 5, c, out obj1HashCode);
      obj2.Count(ref chars, 5, (char)(c - d), out obj2HashCode);
    }

    var chars1 = string.Concat(chars.Where(c => c >= 'A'));
    var chars2 = string.Concat(chars.Where(c => c < 'A'));
    Assert.Equal(expectedChars1, chars1);
    Assert.Equal(expectedChars2, chars2);
    Assert.NotEqual(obj1HashCode, obj2HashCode);
  }

  public class SynchronizedMethodClass
  {
    [MethodImpl(MethodImplOptions.Synchronized)]
    public void Count(ref string chars, int number, char c, out int thisHashCode)
    {
      thisHashCode = this.GetHashCode();

      for (var i = 0; i < number; i++)
      {
        Thread.Sleep(50);

        chars += c;
      }
    }
  }
}

我期望结果"AA11A1A1........DD5D55D"。

感谢所有发表评论的人！的确，我应该更加小心）在这个示例中，我想证明同步实例方法仅在一个线程中被阻止，因为被阻止的对象为`this'。

update

public void SynchronizedInstanceMethodsInDifferentThreads()
{
  var obj1 = new SynchronizedMethodClass();
  var obj2 = new SynchronizedMethodClass();
  var chars = new ConcurrentQueue<char>();
  const string expectedChars1String = "AAAAABBBBBCCCCCDDDDD";
  const string expectedChars2String = "11111222223333344444";
  const int charNumber = 5;
  var th1 = new Thread(() =>
  {
    for (char c = 'A'; c <= 'D'; c++)
    {
      obj1.Count(chars, charNumber, c);
    }
  });
  var th2 = new Thread(() =>
  {
    for (char c = '1'; c <= '4'; c++)
    {
      obj2.Count(chars, charNumber, c);
    }
  });

  th1.Start();
  th2.Start();
  th1.Join();
  th2.Join();

  var charsString = string.Concat(chars);
  var uniqueChars = chars.Distinct();

  // Demonstrates that the object being locked is "this".
  foreach (var uc in uniqueChars)
  {
    var ucSeq = new string(uc, charNumber);
    Assert.DoesNotContain(ucSeq, charsString);
  }

  var chars1String = string.Concat(chars.Where(c => c >= 'A'));
  var chars2String = string.Concat(chars.Where(c => c < 'A'));
  Assert.Equal(expectedChars1String, chars1String);
  Assert.Equal(expectedChars2String, chars2String);
}

Answer 1