docstr: Tests that existing checkpoint directories are read and
  properly registered on all ranks
docstr_tok: ["Tests","that","existing","checkpoint","directories","are","read","and","properly","registered","on","all","ranks"]
code: def _distributed_get_checkpoint_dirpaths() -> None:
      """
      Tests that existing checkpoint directories are read and
      properly registered on all ranks
      """
  
      @rank_zero_read_and_broadcast
      def create_tmp_dir() -> str:
          return tempfile.mkdtemp()
  
      init_from_env()
  
      temp_dir = create_tmp_dir()
      try:
          path1 = os.path.join(temp_dir, "epoch_0_step_10")
          path2 = os.path.join(temp_dir, "epoch_1_step_20")
          if get_global_rank() == 0:
              os.mkdir(path1)
              os.mkdir(path2)
          torch.distributed.barrier()
  
          ckpt_dirpaths = get_checkpoint_dirpaths(temp_dir)
          tc = unittest.TestCase()
          tc.assertEqual(ckpt_dirpaths, [path1, path2])
  
          tc.assertEqual(
              get_checkpoint_dirpaths(
                  temp_dir, metadata_fname=".metadata"
              ),
              [],
          )
      finally:
          if get_global_rank() == 0:
              shutil.rmtree(temp_dir)
  
imports: import os
  import shutil
  import tempfile
  import unittest
  import torch
  import torch.distributed
  from torch import nn
  from torch.distributed import launcher
  from torchsnapshot import Snapshot
  from torchsnapshot.snapshot import SNAPSHOT_METADATA_FNAME
  from torchtnt.framework._test_utils import DummyTrainUnit, get_dummy_train_state
  from torchtnt.framework.callbacks._checkpoint_utils import _delete_checkpoint, _metadata_exists, _prepare_app_state_for_checkpoint, _retrieve_checkpoint_dirpaths, get_checkpoint_dirpaths, get_latest_checkpoint_path, rank_zero_read_and_broadcast
  from torchtnt.utils.distributed import get_global_rank, PGWrapper
  from torchtnt.utils.env import init_from_env
  from torchtnt.utils.fsspec import get_filesystem
  from torchtnt.utils.test_utils import get_pet_launch_config, spawn_multi_process
label_desc: Use image node_id 7 for calling the CheckpointUtilsTest obj's underlying member method code with example usage: obj._distributed_get_checkpoint_dirpaths() and returns: tempfile