test_cachedataset_persistent_workers freeze randomly for pytorch:21.09

[wyli]

Describe the bug

Starting test: test_duplicate_transforms (tests.test_cachedataset_persistent_workers.TestTransformsWCacheDatasetAndPersistentWorkers)...

Loading dataset:   0%|          | 0/1 [00:00<?, ?it/s]
Loading dataset: 100%|██████████| 1/1 [00:00<00:00, 600.47it/s]
Sending interrupt signal to process
Killing processes
kill finished with exit code 0
Sending interrupt signal to process
Killing processes
kill finished with exit code 2

this happens randomly and is difficult to reproduce.

[wyli]

this is still an issue:

Starting test: test_duplicate_transforms (tests.test_cachedataset_persistent_workers.TestTransformsWCacheDatasetAndPersistentWorkers)...
Loading dataset:   0%|          | 0/1 [00:00<?, ?it/s]
Loading dataset: 100%|██████████| 1/1 [00:00<00:00, 108.28it/s]

Sending interrupt signal to process

Killing processes

kill finished with exit code 0

Sending interrupt signal to process

Killing processes

kill finished with exit code 2

Sending interrupt signal to process

Killing processes

kill finished with exit code 2

Sending interrupt signal to process

Killing processes

kill finished with exit code 2

script returned exit code 143