This is the output of my nvidia-smi:
±----------------------------------------------------------------------------+
| Processes:                                                       GPU Memory |
|  GPU       PID   Type   Process name                             Usage      |
|=============================================================================|
|    0      1192      G   /usr/lib/xorg/Xorg                           187MiB |
|    0      2059      G   compiz                                        63MiB |
|    0      2271      G   …-token=6A135D8F234A0DBE5B71ECB1693F9899    48MiB |
|    0      3002      C   python                                      3717MiB |
±----------------------------------------------------------------------------+
Yes, look like running out of memory. I have 4 GB of memory on my graphic card.