c# - 线程正在退出

Question

我有一个线程的小问题。我执行函数 Receive，超时设置为 600，但它在这里结束

if ((thr.ThreadState != ThreadState.Running) 
    && (thr.ThreadState != ThreadState.WaitSleepJoin))
{
  ThreadState st = thr.ThreadState;
  lg.WriteString("EXIT BY THREAD END");
  lg.WriteString("LAST: "+st.ToString());
  break;
}

只有当线程结束并且我已经收到所有数据时，该函数才应该在那里结束，但是当我打开文件 errores.txt 时，我看到 ThreadState 值为 Running 或 WaitSleepJoin。

知道函数为什么会中止吗？

下面有更多代码->

bool exit = false;
void WaitAndRead() {
if (buffer == null)
  buffer = new List<byte>();
buffer.Clear();
try
{
  while (sock_client.Available < 1 && !exit)
    Thread.Sleep(10);
  while (sock_client.Available > 0 && !exit)
  {
    byte[] b = new byte[sock_client.Available];
    sock_client.Receive(b, 0, b.Length, SocketFlags.None);
    buffer.AddRange(b);
    Thread.Sleep(25);
  }
}
catch (Exception ex) 
{ 
  Log lg = new Log("C:\\TPV\\errores.txt"); 
  lg.WriteException(ex, true); 
}

public int Receive(int timeout,out List<byte> result) 
{
  result = new List<byte>();
  try
  {
    if (!Connected)
      return NOT_CONNECTED;
    bool ok = true;
    ThreadStart str = delegate 
    {
      try { WaitAndRead(); }
      catch (Exception ex) 
      { 
        Log lg = new Log("C:\\TPV\\errores.txt"); 
        lg.WriteException(ex, true); ok = false; }
      };
      exit = false;
      Thread thr = new Thread(str);
      thr.Start();
      int x = 0;
      int max = 10 * timeout;
      while (x < max)
      {
        Log lg = new Log("C:\\TPV\\errores.txt");
        if ((thr.ThreadState != ThreadState.Running) 
            && (thr.ThreadState != ThreadState.WaitSleepJoin))
        {
          ThreadState st = thr.ThreadState;
          lg.WriteString("EXIT BY THREAD END");
          lg.WriteString("LAST: "+st.ToString());
          break;
        }
        x++;
        Thread.Sleep(10);
      }
      exit = true;
      if (x >= max)
        return Timeout;
      result = new List<byte>(buffer.ToArray());
      return ok?OK:NOT_CONNECTED;
    }
    catch(Exception ex) 
    {
      Log lg = new Log("C:\\TPV\\errores.txt"); 
      lg.WriteException(ex, true);
      return NOT_CONNECTED;
    }
  }

Answer 1

ThreadState 属性的值可能会在这段代码求值时发生变化:

if ((thr.ThreadState != ThreadState.Running) && (thr.ThreadState != ThreadState.WaitSleepJoin))
{
    ThreadState st = thr.ThreadState;
    lg.WriteString("EXIT BY THREAD END");
    lg.WriteString("LAST: "+st.ToString());
    break;
}

考虑以下场景:

1. thr.ThreadState 是 WaitSleepJoin
2. if 语句的第一部分评估为 true
3. thr.ThreadState 在评估 if 的第二部分之前更改为 Running
4. if 语句的第二部分评估为 true
5. 由于两个部分的计算结果都为 true，因此进入了 if block

您可以尝试重写代码，如下所示，这样您只检查一次 ThreadState 属性的值:

var state = thr.ThreadState;
if (state != ThreadState.Running && state != ThreadState.WaitSleepJoin)
{
    lg.WriteString("EXIT BY THREAD END");
    lg.WriteString("LAST: "+ state.ToString());
    break;
}