How to get the cpu usage per thread on windows (win32)

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Looking for Win32 API functions, C++ or Delphi sample code that tells me the CPU usage (percent and/or total CPU time) of a thread (not the total for a process). I have the thread ID.

I know that Sysinternals Process Explorer can display this information, but I need this information inside my program.

cpu-usage delphi winapi multithreading c++
7 Answers

This example uses GetProcessTimes() but can easily be modified to use GetThreadTimes().

ISO C's clock() is SUPPOSED to give you elapsed CPU-seconds when divided by CLOCKS_PER_SEC. However the Visual Studio 2019 web page says:

The clock function tells how much wall-clock time has passed since the CRT initialization during process start. Note that this function does not strictly conform to ISO C, which specifies net CPU time as the return value.

So, here is a stand-in I made. On Windows 7/Visual Studio 2017, CLOCKS_PER_SEC is 1000 and GetProcessTimes() only has millisecond accuracy, so no accuracy is lost returning clock_t instead of double, say.

clock_t AKClock() {
#ifdef WIN32
  FILETIME  ftimeCreate, ftimeExit, ftimeKernel, ftimeUser;
  SYSTEMTIME stimeKernel, stimeUser;

  if ( ! GetProcessTimes( GetCurrentProcess(), &ftimeCreate, &ftimeExit,
                          &ftimeKernel, &ftimeUser )        ||
       ! FileTimeToSystemTime( &ftimeKernel, &stimeKernel ) ||
       ! FileTimeToSystemTime( &ftimeUser,   &stimeUser   )     ) {
      char szError[ 1024 ];
      MyLoggingFunction( "AKClock() failed; returning -1: %s",
                         AKGetLastError( szError, sizeof( szError ) ) );
      return (clock_t) -1.0;
  }

  return (clock_t)
         ( ( stimeKernel.wHour         * 3600.0 +
             stimeKernel.wMinute       *   60.0 +
             stimeKernel.wSecond                +
             stimeKernel.wMilliseconds / 1000.0 +
             stimeUser.wHour           * 3600.0 +
             stimeUser.wMinute         *   60.0 +
             stimeUser.wSecond                  +
             stimeUser.wMilliseconds   / 1000.0   ) * CLOCKS_PER_SEC );
#else
    return clock();
#endif
}

And for completeness, here's AKGetLastError():

void AKstrncpy( char *pszDest, const char *pszSrc, const size_t sDest ) {

  strncpy( pszDest, pszSrc, sDest );
  pszDest[ sDest - 1 ] = '\0';
}

char* AKGetLastError( char* szBuf, int iBufSize ) {

  DWORD  errorMessageID = GetLastError();
  char*  pszError = NULL;
  size_t sizeBuf;

  if( errorMessageID == 0 ) {
      AKstrncpy( szBuf, "(no error)", iBufSize );
      return szBuf;
  }

  sizeBuf = FormatMessageA(
            FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |
            FORMAT_MESSAGE_IGNORE_INSERTS,
            NULL, errorMessageID, MAKELANGID( LANG_NEUTRAL, SUBLANG_DEFAULT ),
            (LPSTR) &pszError, 0, NULL );

  AKstrncpy( szBuf, pszError, iBufSize );

  LocalFree( pszError );

  int iLen = strlen( szBuf );
  if ( strcmp( szBuf + iLen - 2, "\r\n" ) == 0 )
      szBuf[ iLen - 2 ] = '\0';

  return szBuf;
}
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