I have used the following method in C# .Net to set the running priority for a
process and its affiliated threads. It is noticable at statement (*)
that if the process has already exited, the method will return
immediately without further operations. However, sometimes the method
may generate the following exception:

===========================================================
03/07/04 3:48:06 AM auto_rep.Run() error:
System.InvalidOperationException: The request can not be processed
because the thread (2428) has exited.
   at System.Diagnostics.ProcessManager.OpenThread(Int32 threadId, Int32
access)
   at System.Diagnostics.ProcessThread.OpenThreadHandle(Int32 access)
   at System.Diagnostics.ProcessThread.set_PriorityBoostEnabled(Boolean
value)
   at lib.libs.set_proc_priority(Process proc, Int32 level)
   at DBSample.auto_rep.Run()
===========================================================

The contextual codes calling the method are:

===========================================================
if( libs.work_hour() )
  libs.set_proc_priority( Process.GetCurrentProcess(), 1 );
else
  libs.set_proc_priority( Process.GetCurrentProcess(), 2 );
===========================================================

The full codes of the method are listed as below:

==========================================================
public static void set_proc_priority( Process proc, int level )
{
  int k;

  if( proc.HasExited )                              (*)
    return;
  proc.PriorityBoostEnabled = true;
  switch( level )
  {
    case( -2 ):
      proc.PriorityClass = ProcessPriorityClass.Idle;
      for( k = 0; k < proc.Threads.Count; k++ )
      {
    proc.Threads[k].PriorityBoostEnabled = true;
    proc.Threads[k].PriorityLevel = ThreadPriorityLevel.Idle;
      }
      break;
    case( -1 ):
      proc.PriorityClass = ProcessPriorityClass.BelowNormal;
      for( k = 0; k < proc.Threads.Count; k++ )
      {
    proc.Threads[k].PriorityBoostEnabled = true;
    proc.Threads[k].PriorityLevel = ThreadPriorityLevel.BelowNormal;
      }
      break;
    case( 0 ):
      proc.PriorityClass = ProcessPriorityClass.Normal;
      for( k = 0; k < proc.Threads.Count; k++ )
      {
    proc.Threads[k].PriorityBoostEnabled = true;
    proc.Threads[k].PriorityLevel = ThreadPriorityLevel.Normal;
      }
      break;
    case( 1 ):
      proc.PriorityClass = ProcessPriorityClass.AboveNormal;
      for( k = 0; k < proc.Threads.Count; k++ )
      {
    proc.Threads[k].PriorityBoostEnabled = true;
    proc.Threads[k].PriorityLevel = ThreadPriorityLevel.AboveNormal;
      }
      break;
    case( 2 ):
      proc.PriorityClass = ProcessPriorityClass.High;
      for( k = 0; k < proc.Threads.Count; k++ )
      {
    proc.Threads[k].PriorityBoostEnabled = true;
    proc.Threads[k].PriorityLevel = ThreadPriorityLevel.Highest;
      }
      break;
    case( 3 ):
      proc.PriorityClass = ProcessPriorityClass.RealTime;
      for( k = 0; k < proc.Threads.Count; k++ )
      {
    proc.Threads[k].PriorityBoostEnabled = true;
    proc.Threads[k].PriorityLevel = ThreadPriorityLevel.TimeCritical;
      }
      break;
  }
  return;
}
==========================================================


Any solution to the problem?

来自.net framwork文档

当方法调用对于对象的当前状态无效时引发的异常。

有关此类型所有成员的列表，请参阅 InvalidOperationException 成员。

System.Object
   System.Exception
      System.SystemException
         System.InvalidOperationException
            System.Net.ProtocolViolationException
            System.Net.WebException
            System.ObjectDisposedException

[Visual Basic]
<Serializable>
Public Class InvalidOperationException
   Inherits SystemException

[C#]
[Serializable]
public class InvalidOperationException : SystemException

[C++]
[Serializable]
public __gc class InvalidOperationException : public
   SystemException

[JScript]
public
   Serializable
class InvalidOperationException extends SystemException

线程安全
此类型的所有公共静态（Visual Basic 中为 Shared）成员对多线程操作而言都是安全的。但不保证任何实例成员是线程安全的。

备注
如果调用方法失败不是由无效参数造成的，则使用 InvalidOperationException。例如，对于 InvalidOperationException 而言：

如果创建枚举数后修改了集合中的对象，则由 MoveNext 引发该异常。
如果执行方法调用前关闭了资源集，则由 GetString 引发该异常。
如果方法调用失败是由无效参数造成的，则应改为引发 ArgumentException 或其派生类 ArgumentNullException 或 ArgumentOutOfRangeException。

Ldflda Microsoft 中间语言 (MSIL) 指令引发 InvalidOperationException。
InvalidOperationException 使用值为 0x80131509 的 HRESULT COR_E_INVALIDOPERATION。

有关 InvalidOperationException 的实例的初始属性值列表，请参见 InvalidOperationException 构造函数。