While using torch.cuda.sychronize(), there is a type error of isinstance()

Question

I am learning python torch nowadays. There was a good example for newbies on youtube. (https://youtu.be/r9IqwpMR9TE?si=VYCbx3O-3BX9pPZx&t=887) It uses pytorch cuda library. It shows the time spent calculating via CPU and GPU respectively.

When i tried to run there is an error on calling a function. torch.cuda.synchronize()

Here is error code:

Traceback (most recent call last):
  File "c:\Users\msaid\OneDrive - Bingöl Üniversitesi\Python\erMeydani\Vyeni\CUDAtest.py", line 25, in <module>
    torch.cuda.synchronize()
  File "C:\Program Files\Python311\Lib\site-packages\torch\cuda\__init__.py", line 687, in synchronize
    with torch.cuda.device(device):
         ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Program Files\Python311\Lib\site-packages\torch\cuda\__init__.py", line 312, in __init__
    self.idx = _get_device_index(device, optional=True)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Program Files\Python311\Lib\site-packages\torch\cuda\_utils.py", line 27, in _get_device_index
    if isinstance(device, torch.device):
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: isinstance() arg 2 must be a type, a tuple of types, or a union

and here is my sample code:

import torch
torch.cuda.empty_cache()
if torch.cuda.is_available():
   device=torch.device=("cuda")

else:
   device=torch.device=("cpu")

print("using", device)

import time

matrix_size= 32*256
x=torch.randn(matrix_size, matrix_size)
y=torch.randn(matrix_size, matrix_size)

print("*******************CPU SPEED*********************")
start=time.time()
result=torch.matmul(x,y)
print(time.time()-start)
print("verify device", result.device)

x_gpu=x.to(device)
y_gpu=y.to(device)
torch.cuda.synchronize()

for i in range(3):
   print("*******************GPU SPEED*********************")
   start=time.time()
   result_gpu=torch.matmul(x_gpu,y_gpu)
   print(time.time()-start)
   print("verify device", result_gpu.device)

I tried to call function with device variable torch.cuda.synchronize(device), but same error again.

Answer 1

The problem is in these lines of code:

if torch.cuda.is_available():
   device=torch.device=("cuda")

else:
   device=torch.device=("cpu")

replace torch.device=("cuda") by torch.device("cuda"), likewise for cpu.