in_grads.push_back(zero);
      } else {
        in_grads.push_back(nullptr);
      }
    } else {
      in_grads.push_back(current_grad->second);
    }
  }

  // Avoid infinite recursion. Whichever forward function we run, it'll end up
  // executing ops, and we don't want to watch those with this accumulator.
  call_state_.emplace(nullptr, true);

	
	if(nthread > MaxThread)
		nthread = MaxThread;
	for(i=0; i<nthread; i++)
		thread_id[i] = _beginthreadex(0, 0, addThread, &max, 0, 0);
	for(i=0; i<nthread; i++) {
		WaitForSingleObject((HANDLE)thread_id[i], INFINITE);
		CloseHandle((HANDLE)thread_id[i]);
	}
}

__stdcall
static unsigned int
goDummyCallbackThread(void* p)
{
	int i, max;

	max = *(int*)p;
	for(i=0; i<max; i++)
		goDummy();
	return 0;