/*=========================================================================

  Program:   Visualization Toolkit
  Module:    $RCSfile: vtkMultiThreader.cxx,v $
  Language:  C++
  Date:      $Date: 2003/01/29 21:14:52 $
  Version:   $Revision: 1.43 $

  Copyright (c) 1993-2002 Ken Martin, Will Schroeder, Bill Lorensen 
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even 
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
#include "vtkMultiThreader.h"

#include "vtkMutexLock.h"
#include "vtkObjectFactory.h"

vtkCxxRevisionMacro(vtkMultiThreader, "$Revision: 1.43 $");
vtkStandardNewMacro(vtkMultiThreader);

// These are the includes necessary for multithreaded rendering on an SGI
// using the sproc() call
#ifdef VTK_USE_SPROC
#include <sys/resource.h>
#include <sys/prctl.h>
#include <wait.h>
#include <errno.h>
#endif

// Need to define "vtkExternCThreadFunctionType" to avoid warning on some
// platforms about passing function pointer to an argument expecting an
// extern "C" function.  Placing the typedef of the function pointer type
// inside an extern "C" block solves this problem.
#if defined(VTK_USE_PTHREADS) || defined(VTK_HP_PTHREADS)
#include <pthread.h>
extern "C" { typedef void *(*vtkExternCThreadFunctionType)(void *); }
#else
typedef vtkThreadFunctionType vtkExternCThreadFunctionType;
#endif

#ifdef __APPLE__
#include <Carbon/Carbon.h>
#endif

// Initialize static member that controls global maximum number of threads
static int vtkMultiThreaderGlobalMaximumNumberOfThreads = 0;

void vtkMultiThreader::SetGlobalMaximumNumberOfThreads(int val)
{
  if (val == vtkMultiThreaderGlobalMaximumNumberOfThreads)
    {
    return;
    }
  vtkMultiThreaderGlobalMaximumNumberOfThreads = val;
}

int vtkMultiThreader::GetGlobalMaximumNumberOfThreads()
{
  return vtkMultiThreaderGlobalMaximumNumberOfThreads;
}

// 0 => Not initialized.
static int vtkMultiThreaderGlobalDefaultNumberOfThreads = 0;

void vtkMultiThreader::SetGlobalDefaultNumberOfThreads(int val)
{
  if (val == vtkMultiThreaderGlobalDefaultNumberOfThreads)
    {
    return;
    }
  vtkMultiThreaderGlobalDefaultNumberOfThreads = val;
}

int vtkMultiThreader::GetGlobalDefaultNumberOfThreads()
{
  if (vtkMultiThreaderGlobalDefaultNumberOfThreads == 0)
    {
    int num = 1; // default is 1
#ifdef VTK_USE_SPROC
    // Default the number of threads to be the number of available
    // processors if we are using sproc()
    num = prctl( PR_MAXPPROCS );
#endif

#ifdef VTK_USE_PTHREADS
    // Default the number of threads to be the number of available
    // processors if we are using pthreads()
#ifdef _SC_NPROCESSORS_ONLN
    num = sysconf( _SC_NPROCESSORS_ONLN );
#elif defined(_SC_NPROC_ONLN)
    num = sysconf( _SC_NPROC_ONLN );
#endif
#if defined(__SVR4) && defined(sun) && defined(PTHREAD_MUTEX_NORMAL)
    pthread_setconcurrency(num);
#endif
#endif

#ifdef __APPLE__
    // MPProcessors returns the physical number of processors present
    // MPProcessorsScheduled returns number of active processors
    num = MPProcessors();
#endif

#ifdef _WIN32
    {
      SYSTEM_INFO sysInfo;
      GetSystemInfo(&sysInfo);
      num = sysInfo.dwNumberOfProcessors;
    }
#endif

#ifndef VTK_USE_WIN32_THREADS
#ifndef VTK_USE_SPROC
#ifndef VTK_USE_PTHREADS
    // If we are not multithreading, the number of threads should
    // always be 1
    num = 1;
#endif  
#endif  
#endif
  
    // Lets limit the number of threads to VTK_MAX_THREADS
    if (num > VTK_MAX_THREADS)
      {
      num = VTK_MAX_THREADS;
      }

    vtkMultiThreaderGlobalDefaultNumberOfThreads = num;
    }


  return vtkMultiThreaderGlobalDefaultNumberOfThreads;
}

// Constructor. Default all the methods to NULL. Since the
// ThreadInfoArray is static, the ThreadIDs can be initialized here
// and will not change.
vtkMultiThreader::vtkMultiThreader()
{
  int i;

  for ( i = 0; i < VTK_MAX_THREADS; i++ )
    {
    this->ThreadInfoArray[i].ThreadID           = i;
    this->ThreadInfoArray[i].ActiveFlag         = NULL;
    this->ThreadInfoArray[i].ActiveFlagLock     = NULL;
    this->MultipleMethod[i]                     = NULL;
    this->SpawnedThreadActiveFlag[i]            = 0;
    this->SpawnedThreadActiveFlagLock[i]        = NULL;
    this->SpawnedThreadInfoArray[i].ThreadID    = i;
    }

  this->SingleMethod = NULL;
  this->NumberOfThreads = 
    vtkMultiThreader::GetGlobalDefaultNumberOfThreads();

}

// Destructor. Nothing allocated so nothing needs to be done here.
vtkMultiThreader::~vtkMultiThreader()
{
}

// Set the user defined method that will be run on NumberOfThreads threads
// when SingleMethodExecute is called.
void vtkMultiThreader::SetSingleMethod( vtkThreadFunctionType f, 
                                        void *data )
{ 
  this->SingleMethod = f;
  this->SingleData   = data;
}

// Set one of the user defined methods that will be run on NumberOfThreads
// threads when MultipleMethodExecute is called. This method should be
// called with index = 0, 1, ..,  NumberOfThreads-1 to set up all the
// required user defined methods
void vtkMultiThreader::SetMultipleMethod( int index, 
                                          vtkThreadFunctionType f, void *data )
{ 
  // You can only set the method for 0 through NumberOfThreads-1
  if ( index >= this->NumberOfThreads ) {
    vtkErrorMacro( << "Can't set method " << index << 
    " with a thread count of " << this->NumberOfThreads );
    }
  else
    {
    this->MultipleMethod[index] = f;
    this->MultipleData[index]   = data;
    }
}

// Execute the method set as the SingleMethod on NumberOfThreads threads.
void vtkMultiThreader::SingleMethodExecute()
{
  int                thread_loop = 0;

#ifdef VTK_USE_WIN32_THREADS
  DWORD              threadId;
  HANDLE             process_id[VTK_MAX_THREADS];
#endif

#ifdef VTK_USE_SPROC
  siginfo_t          info_ptr;
  int                process_id[VTK_MAX_THREADS];
#endif

#ifdef VTK_USE_PTHREADS
  pthread_t          process_id[VTK_MAX_THREADS];
#endif

  if ( !this->SingleMethod )
    {
    vtkErrorMacro( << "No single method set!" );
    return;
    }

  // obey the global maximum number of threads limit
  if (vtkMultiThreaderGlobalMaximumNumberOfThreads &&
      this->NumberOfThreads > vtkMultiThreaderGlobalMaximumNumberOfThreads)
    {
    this->NumberOfThreads = vtkMultiThreaderGlobalMaximumNumberOfThreads;
    }
  
    
  // We are using sproc (on SGIs), pthreads(on Suns), or a single thread
  // (the default)  

#ifdef VTK_USE_WIN32_THREADS
  // Using CreateThread on a PC
  //
  // We want to use CreateThread to start this->NumberOfThreads - 1 
  // additional threads which will be used to call this->SingleMethod().
  // The parent thread will also call this routine.  When it is done,
  // it will wait for all the children to finish. 
  //
  // First, start up the this->NumberOfThreads-1 processes.  Keep track
  // of their process ids for use later in the waitid call
  for (thread_loop = 1; thread_loop < this->NumberOfThreads; thread_loop++ )
    {
    this->ThreadInfoArray[thread_loop].UserData    = this->SingleData;
    this->ThreadInfoArray[thread_loop].NumberOfThreads = this->NumberOfThreads;
    process_id[thread_loop] = 
      CreateThread(NULL, 0, this->SingleMethod, 
             ((void *)(&this->ThreadInfoArray[thread_loop])), 0, &threadId);
    if (process_id == NULL)
      {
      vtkErrorMacro("Error in thread creation !!!");
      } 
    }
  
  // Now, the parent thread calls this->SingleMethod() itself
  this->ThreadInfoArray[0].UserData = this->SingleData;
  this->ThreadInfoArray[0].NumberOfThreads = this->NumberOfThreads;
  this->SingleMethod((void *)(&this->ThreadInfoArray[0]));

  // The parent thread has finished this->SingleMethod() - so now it
  // waits for each of the other processes to exit
  for ( thread_loop = 1; thread_loop < this->NumberOfThreads; thread_loop++ )
    {
    WaitForSingleObject(process_id[thread_loop], INFINITE);
    }

  // close the threads
  for ( thread_loop = 1; thread_loop < this->NumberOfThreads; thread_loop++ )
    {
    CloseHandle(process_id[thread_loop]);
    }
#endif

#ifdef VTK_USE_SPROC
  // Using sproc() on an SGI
  //
  // We want to use sproc to start this->NumberOfThreads - 1 additional
  // threads which will be used to call this->SingleMethod(). The
  // parent thread will also call this routine.  When it is done,
  // it will wait for all the children to finish. 
  //
  // First, start up the this->NumberOfThreads-1 processes.  Keep track
  // of their process ids for use later in the waitid call

  for ( thread_loop = 1; thread_loop < this->NumberOfThreads; thread_loop++ )
    {
    this->ThreadInfoArray[thread_loop].UserData    = this->SingleData;
    this->ThreadInfoArray[thread_loop].NumberOfThreads = this->NumberOfThreads;
    process_id[thread_loop] = 
      sproc( this->SingleMethod, PR_SADDR, 
             ( (void *)(&this->ThreadInfoArray[thread_loop]) ) );
    if ( process_id[thread_loop] == -1)
      {
      vtkErrorMacro("sproc call failed. Code: " << errno << endl);
      }
    }
  
  // Now, the parent thread calls this->SingleMethod() itself
  this->ThreadInfoArray[0].UserData = this->SingleData;
  this->ThreadInfoArray[0].NumberOfThreads = this->NumberOfThreads;
  this->SingleMethod((void *)(&this->ThreadInfoArray[0]) );

  // The parent thread has finished this->SingleMethod() - so now it
  // waits for each of the other processes to exit
  for ( thread_loop = 1; thread_loop < this->NumberOfThreads; thread_loop++ )
    {
    waitid( P_PID, (id_t) process_id[thread_loop], &info_ptr, WEXITED );
    }
#endif

#ifdef VTK_USE_PTHREADS
  // Using POSIX threads
  //
  // We want to use pthread_create to start this->NumberOfThreads-1 additional
  // threads which will be used to call this->SingleMethod(). The
  // parent thread will also call this routine.  When it is done,
  // it will wait for all the children to finish. 
  //
  // First, start up the this->NumberOfThreads-1 processes.  Keep track
  // of their process ids for use later in the pthread_join call

  pthread_attr_t attr;

#ifdef VTK_HP_PTHREADS
  pthread_attr_create( &attr );
#else  
  pthread_attr_init(&attr);
#if !defined(__CYGWIN__)
  pthread_attr_setscope(&attr, PTHREAD_SCOPE_PROCESS);
#endif
#endif
  
  for ( thread_loop = 1; thread_loop < this->NumberOfThreads; thread_loop++ )
    {
    this->ThreadInfoArray[thread_loop].UserData    = this->SingleData;
    this->ThreadInfoArray[thread_loop].NumberOfThreads = this->NumberOfThreads;

#ifdef VTK_HP_PTHREADS
    pthread_create( &(process_id[thread_loop]),
                    attr, this->SingleMethod,  
                    ( (void *)(&this->ThreadInfoArray[thread_loop]) ) );
#else
    int                threadError;
    threadError =
      pthread_create( &(process_id[thread_loop]), &attr,
                      reinterpret_cast<vtkExternCThreadFunctionType>(
                        this->SingleMethod),
                      ( (void *)(&this->ThreadInfoArray[thread_loop]) ) );
    if (threadError != 0)
      {
      vtkErrorMacro(<< "Unable to create a thread.  pthread_create() returned "
                    << threadError);
      }
#endif
    }
  
  // Now, the parent thread calls this->SingleMethod() itself
  this->ThreadInfoArray[0].UserData = this->SingleData;
  this->ThreadInfoArray[0].NumberOfThreads = this->NumberOfThreads;
  this->SingleMethod((void *)(&this->ThreadInfoArray[0]) );

  // The parent thread has finished this->SingleMethod() - so now it
  // waits for each of the other processes to exit
  for ( thread_loop = 1; thread_loop < this->NumberOfThreads; thread_loop++ )
    {
    pthread_join( process_id[thread_loop], NULL );
    }
#endif

#ifndef VTK_USE_WIN32_THREADS
#ifndef VTK_USE_SPROC
#ifndef VTK_USE_PTHREADS
  // There is no multi threading, so there is only one thread.
  this->ThreadInfoArray[0].UserData    = this->SingleData;
  this->ThreadInfoArray[0].NumberOfThreads = this->NumberOfThreads;
  this->SingleMethod( (void *)(&this->ThreadInfoArray[0]) );
#endif
#endif
#endif
}

void vtkMultiThreader::MultipleMethodExecute()
{
  int                thread_loop;

#ifdef VTK_USE_WIN32_THREADS
  DWORD              threadId;
  HANDLE             process_id[VTK_MAX_THREADS];
#endif

#ifdef VTK_USE_SPROC
  siginfo_t          info_ptr;
  int                process_id[VTK_MAX_THREADS];
#endif

#ifdef VTK_USE_PTHREADS
  pthread_t          process_id[VTK_MAX_THREADS];
#endif


  // obey the global maximum number of threads limit
  if (vtkMultiThreaderGlobalMaximumNumberOfThreads &&
      this->NumberOfThreads > vtkMultiThreaderGlobalMaximumNumberOfThreads)
    {
    this->NumberOfThreads = vtkMultiThreaderGlobalMaximumNumberOfThreads;
    }

  for ( thread_loop = 0; thread_loop < this->NumberOfThreads; thread_loop++ )
    {
    if ( this->MultipleMethod[thread_loop] == (vtkThreadFunctionType)NULL)
      {
      vtkErrorMacro( << "No multiple method set for: " << thread_loop );
      return;
      }
    }

  // We are using sproc (on SGIs), pthreads(on Suns), CreateThread
  // on a PC or a single thread (the default)  

#ifdef VTK_USE_WIN32_THREADS
  // Using CreateThread on a PC
  //
  // We want to use CreateThread to start this->NumberOfThreads - 1 
  // additional threads which will be used to call the NumberOfThreads-1
  // methods defined in this->MultipleMethods[](). The parent thread
  // will call this->MultipleMethods[NumberOfThreads-1]().  When it is done,
  // it will wait for all the children to finish. 
  //
  // First, start up the this->NumberOfThreads-1 processes.  Keep track
  // of their process ids for use later in the waitid call
  for ( thread_loop = 1; thread_loop < this->NumberOfThreads; thread_loop++ )
    {
    this->ThreadInfoArray[thread_loop].UserData = 
      this->MultipleData[thread_loop];
    this->ThreadInfoArray[thread_loop].NumberOfThreads = this->NumberOfThreads;
    process_id[thread_loop] = 
      CreateThread(NULL, 0, this->MultipleMethod[thread_loop], 
             ((void *)(&this->ThreadInfoArray[thread_loop])), 0, &threadId);
    if (process_id == NULL)
      {
      vtkErrorMacro("Error in thread creation !!!");
      } 
    }
  
  // Now, the parent thread calls the last method itself
  this->ThreadInfoArray[0].UserData = this->MultipleData[0];
  this->ThreadInfoArray[0].NumberOfThreads = this->NumberOfThreads;
  (this->MultipleMethod[0])((void *)(&this->ThreadInfoArray[0]) );

  // The parent thread has finished its method - so now it
  // waits for each of the other processes (created with sproc) to
  // exit
  for ( thread_loop = 1; thread_loop < this->NumberOfThreads; thread_loop++ )
    {
    WaitForSingleObject(process_id[thread_loop], INFINITE);
    }

  // close the threads
  for ( thread_loop = 1; thread_loop < this->NumberOfThreads; thread_loop++ )
    {
    CloseHandle(process_id[thread_loop]);
    }
#endif

#ifdef VTK_USE_SPROC
  // Using sproc() on an SGI
  //
  // We want to use sproc to start this->NumberOfThreads - 1 additional
  // threads which will be used to call the NumberOfThreads-1 methods
  // defined in this->MultipleMethods[](). The parent thread
  // will call this->MultipleMethods[NumberOfThreads-1]().  When it is done,
  // it will wait for all the children to finish. 
  //
  // First, start up the this->NumberOfThreads-1 processes.  Keep track
  // of their process ids for use later in the waitid call
  for ( thread_loop = 1; thread_loop < this->NumberOfThreads; thread_loop++ )
    {
    this->ThreadInfoArray[thread_loop].UserData = 
      this->MultipleData[thread_loop];
    this->ThreadInfoArray[thread_loop].NumberOfThreads = this->NumberOfThreads;
    process_id[thread_loop] = 
      sproc( this->MultipleMethod[thread_loop], PR_SADDR, 
             ( (void *)(&this->ThreadInfoArray[thread_loop]) ) );
    }
  
  // Now, the parent thread calls the last method itself
  this->ThreadInfoArray[0].UserData = this->MultipleData[0];
  this->ThreadInfoArray[0].NumberOfThreads = this->NumberOfThreads;
  (this->MultipleMethod[0])((void *)(&this->ThreadInfoArray[0]) );

  // The parent thread has finished its method - so now it
  // waits for each of the other processes (created with sproc) to
  // exit
  for ( thread_loop = 1; thread_loop < this->NumberOfThreads; thread_loop++ )
    {
    waitid( P_PID, (id_t) process_id[thread_loop], &info_ptr, WEXITED );
    }
#endif

#ifdef VTK_USE_PTHREADS
  // Using POSIX threads
  //
  // We want to use pthread_create to start this->NumberOfThreads - 1 
  // additional
  // threads which will be used to call the NumberOfThreads-1 methods
  // defined in this->MultipleMethods[](). The parent thread
  // will call this->MultipleMethods[NumberOfThreads-1]().  When it is done,
  // it will wait for all the children to finish. 
  //
  // First, start up the this->NumberOfThreads-1 processes.  Keep track
  // of their process ids for use later in the pthread_join call

  pthread_attr_t attr;

#ifdef VTK_HP_PTHREADS
  pthread_attr_create( &attr );
#else  
  pthread_attr_init(&attr);
#ifndef __CYGWIN__
  pthread_attr_setscope(&attr, PTHREAD_SCOPE_PROCESS);
#endif
#endif

  for ( thread_loop = 1; thread_loop < this->NumberOfThreads; thread_loop++ )
    {
    this->ThreadInfoArray[thread_loop].UserData = 
      this->MultipleData[thread_loop];
    this->ThreadInfoArray[thread_loop].NumberOfThreads = this->NumberOfThreads;
#ifdef VTK_HP_PTHREADS
    pthread_create( &(process_id[thread_loop]),
                    attr, this->MultipleMethod[thread_loop],  
                    ( (void *)(&this->ThreadInfoArray[thread_loop]) ) );
#else
    pthread_create( &(process_id[thread_loop]),
                    &attr,
                    reinterpret_cast<vtkExternCThreadFunctionType>(
                      this->MultipleMethod[thread_loop]),
                    ( (void *)(&this->ThreadInfoArray[thread_loop]) ) );
#endif
    }
  
  // Now, the parent thread calls the last method itself
  this->ThreadInfoArray[0].UserData = this->MultipleData[0];
  this->ThreadInfoArray[0].NumberOfThreads = this->NumberOfThreads;
  (this->MultipleMethod[0])((void *)(&this->ThreadInfoArray[0]) );

  // The parent thread has finished its method - so now it
  // waits for each of the other processes to exit
  for ( thread_loop = 1; thread_loop < this->NumberOfThreads; thread_loop++ )
    {
    pthread_join( process_id[thread_loop], NULL );
    }
#endif

#ifndef VTK_USE_WIN32_THREADS
#ifndef VTK_USE_SPROC
#ifndef VTK_USE_PTHREADS
  // There is no multi threading, so there is only one thread.
  this->ThreadInfoArray[0].UserData    = this->MultipleData[0];
  this->ThreadInfoArray[0].NumberOfThreads = this->NumberOfThreads;
  (this->MultipleMethod[0])( (void *)(&this->ThreadInfoArray[0]) );
#endif
#endif
#endif
}

int vtkMultiThreader::SpawnThread( vtkThreadFunctionType f, void *UserData )
{
  int id;

  // avoid a warning
  vtkThreadFunctionType tf;
  tf = f; tf= tf;
  
#ifdef VTK_USE_WIN32_THREADS
  DWORD              threadId;
#endif

  id = 0;

  while ( id < VTK_MAX_THREADS )
    {
    if ( this->SpawnedThreadActiveFlagLock[id] == NULL )
      {
      this->SpawnedThreadActiveFlagLock[id] = vtkMutexLock::New();
      }
    this->SpawnedThreadActiveFlagLock[id]->Lock();
    if (this->SpawnedThreadActiveFlag[id] == 0)
      {
      // We've got a useable thread id, so grab it
      this->SpawnedThreadActiveFlag[id] = 1;
      this->SpawnedThreadActiveFlagLock[id]->Unlock();
      break;
      }
    this->SpawnedThreadActiveFlagLock[id]->Unlock();
      
    id++;
    }

  if ( id >= VTK_MAX_THREADS )
    {
    vtkErrorMacro( << "You have too many active threads!" );
    return -1;
    }


  this->SpawnedThreadInfoArray[id].UserData        = UserData;
  this->SpawnedThreadInfoArray[id].NumberOfThreads = 1;
  this->SpawnedThreadInfoArray[id].ActiveFlag = 
    &this->SpawnedThreadActiveFlag[id];
  this->SpawnedThreadInfoArray[id].ActiveFlagLock = 
    this->SpawnedThreadActiveFlagLock[id];

  // We are using sproc (on SGIs), pthreads(on Suns or HPs), 
  // CreateThread (on win32), or generating an error  

#ifdef VTK_USE_WIN32_THREADS
  // Using CreateThread on a PC
  //
  this->SpawnedThreadProcessID[id] = 
      CreateThread(NULL, 0, f, 
             ((void *)(&this->SpawnedThreadInfoArray[id])), 0, &threadId);
  if (this->SpawnedThreadProcessID[id] == NULL)
    {
    vtkErrorMacro("Error in thread creation !!!");
    } 
#endif

#ifdef VTK_USE_SPROC
  // Using sproc() on an SGI
  //
  this->SpawnedThreadProcessID[id] = 
    sproc( f, PR_SADDR, ( (void *)(&this->SpawnedThreadInfoArray[id]) ) );

#endif

#ifdef VTK_USE_PTHREADS
  // Using POSIX threads
  //
  pthread_attr_t attr;

#ifdef VTK_HP_PTHREADS
  pthread_attr_create( &attr );
#else  
  pthread_attr_init(&attr);
#ifndef __CYGWIN__
  pthread_attr_setscope(&attr, PTHREAD_SCOPE_PROCESS);
#endif
#endif
  
#ifdef VTK_HP_PTHREADS
  pthread_create( &(this->SpawnedThreadProcessID[id]),
                  attr, f,  
                  ( (void *)(&this->SpawnedThreadInfoArray[id]) ) );
#else
  pthread_create( &(this->SpawnedThreadProcessID[id]),
                  &attr,
                  reinterpret_cast<vtkExternCThreadFunctionType>(f),  
                  ( (void *)(&this->SpawnedThreadInfoArray[id]) ) );
#endif

#endif

#ifndef VTK_USE_WIN32_THREADS
#ifndef VTK_USE_SPROC
#ifndef VTK_USE_PTHREADS
  // There is no multi threading, so there is only one thread.
  // This won't work - so give an error message.
  vtkErrorMacro( << "Cannot spawn thread in a single threaded environment!" );
  this->SpawnedThreadActiveFlagLock[id]->Delete();
  id = -1;
#endif
#endif
#endif

  return id;
}

void vtkMultiThreader::TerminateThread( int ThreadID )
{

  if ( !this->SpawnedThreadActiveFlag[ThreadID] ) {
    return;
  }

  this->SpawnedThreadActiveFlagLock[ThreadID]->Lock();
  this->SpawnedThreadActiveFlag[ThreadID] = 0;
  this->SpawnedThreadActiveFlagLock[ThreadID]->Unlock();

#ifdef VTK_USE_WIN32_THREADS
  WaitForSingleObject(this->SpawnedThreadProcessID[ThreadID], INFINITE);
  CloseHandle(this->SpawnedThreadProcessID[ThreadID]);
#endif

#ifdef VTK_USE_SPROC
  siginfo_t info_ptr;

  waitid( P_PID, (id_t) this->SpawnedThreadProcessID[ThreadID], 
          &info_ptr, WEXITED );
#endif

#ifdef VTK_USE_PTHREADS
  pthread_join( this->SpawnedThreadProcessID[ThreadID], NULL );
#endif

#ifndef VTK_USE_WIN32_THREADS
#ifndef VTK_USE_SPROC
#ifndef VTK_USE_PTHREADS
  // There is no multi threading, so there is only one thread.
  // This won't work - so give an error message.
  vtkErrorMacro(<< "Cannot terminate thread in single threaded environment!");
#endif
#endif
#endif

  this->SpawnedThreadActiveFlagLock[ThreadID]->Delete();
  this->SpawnedThreadActiveFlagLock[ThreadID] = NULL;

}

// Print method for the multithreader
void vtkMultiThreader::PrintSelf(ostream& os, vtkIndent indent)
{
  this->Superclass::PrintSelf(os,indent); 

  os << indent << "Thread Count: " << this->NumberOfThreads << "\n";
  os << indent << "Global Maximum Number Of Threads: " << 
    vtkMultiThreaderGlobalMaximumNumberOfThreads << endl;
  os << "Thread system used: " <<
#ifdef VTK_USE_PTHREADS  
   "PTHREADS"
#elif defined VTK_USE_SPROC
    "SPROC"
#elif defined VTK_USE_WIN32_THREADS
    "WIN32 Threads"
#elif defined VTK_HP_PTHREADS
    "HP PThreads"
#else
    "NO THREADS SUPPORT"
#endif
     << endl;
}
