why always get the leaked semaphore warning?

[jxchen01]

Hello, whenever I run this sample code (https://github.com/MMV-Lab/demo_box/blob/main/monai_w_plt_multigpu_bioimage.py) with 2 gpus, I always get the following error:

UserWarning: resource_tracker: There appear to be 20 leaked semaphore objects to clean up at shutdown

Any suggestions?

[akihironitta]

@jxchen01 Could you paste the full traceback and your environment details?

[jxchen01]

there is not much trackback, only at the end of the whole training as a warning:

Epoch 4: 100%|████████████████████████████████████████████████████████████████████████████| 2/2 [00:03<00:00,  1.98s/it, loss=0.49]
/mnt/data/ISAS.DE/jianxu.chen/anaconda3/envs/multigpu/lib/python3.9/site-packages/pytorch_lightning/plugins/training_type/ddp_spawn.py:307: UserWarning: cleaning up ddp environment...
  rank_zero_warn("cleaning up ddp environment...")
/mnt/data/ISAS.DE/jianxu.chen/anaconda3/envs/multigpu/lib/python3.9/multiprocessing/resource_tracker.py:216: UserWarning: resource_tracker: There appear to be 20 leaked semaphore objects to clean up at shutdown
  warnings.warn('resource_tracker: There appear to be %d '