Fix recorder dataset filename collision in shared /tmp (#469)

## Summary

- Always append a timestamp and rank to the recorder dataset filename
- Previously this was only done in distributed mode (to avoid HDF5 file
lock conflicts between ranks); now it also prevents permission errors
when multiple processes or repeated runs share `/tmp` in the container
- Non-distributed runs just get a `_rank0` suffix


`/tmp` is mounted and shared across container processes. All runs write
to `/tmp/isaaclab/logs/dataset.hdf5`. If the file was created by a
different process/user, subsequent runs get `PermissionError: [Errno 13]
Unable to synchronously create file`.

Signed-off-by: Clemens Volk <cvolk@nvidia.com>

Author: cvolkcvolk

isaaclab_arena/environments/arena_env_builder.py

@@ -6,6 +6,7 @@
 from __future__ import annotations
 
 import argparse
+import datetime
 import gymnasium as gym
 
 from isaaclab.envs import ManagerBasedRLMimicEnv
@@ -91,13 +92,12 @@ def _solve_relations(self) -> None:
         else:
             print(f"Relation solving not completed after {result.attempts} attempt(s)")
 
-    def _modify_recorder_cfg_for_distributed(self, recorder_cfg: RecorderManagerBaseCfg) -> RecorderManagerBaseCfg:
-        """Modify the recorder dataset filename for distributed multi-gpu envs.
-        This is to avoid HDF5 file lock conflict when distributed: each rank uses a unique dataset filename.
-        """
-        if getattr(self.args, "distributed", False):
-            base = getattr(recorder_cfg, "dataset_filename", "dataset")
-            recorder_cfg.dataset_filename = f"{base}_rank{get_local_rank()}"
+    def _modify_recorder_cfg_dataset_filename(self, recorder_cfg: RecorderManagerBaseCfg) -> RecorderManagerBaseCfg:
+        """Modify the recorder dataset filename to include the timestamp and rank."""
+        base = getattr(recorder_cfg, "dataset_filename", "dataset")
+        recorder_cfg.dataset_filename = (
+            f"{base}_{datetime.datetime.now().strftime('%Y%m%d_%H%M%S')}_rank{get_local_rank()}"
+        )
         return recorder_cfg
 
     # This method gives the arena environment a chance to modify the environment configuration.
@@ -168,8 +168,7 @@ def compose_manager_cfg(self) -> IsaacLabArenaManagerBasedRLEnvCfg:
             embodiment.get_recorder_term_cfg(),
             bases=(RecorderManagerBaseCfg,),
         )
-        # Only modify the recorder configuration for distributed multi-gpu envs.
-        recorder_manager_cfg = self._modify_recorder_cfg_for_distributed(recorder_manager_cfg)
+        recorder_manager_cfg = self._modify_recorder_cfg_dataset_filename(recorder_manager_cfg)
 
         rewards_cfg = combine_configclass_instances(
             "RewardsCfg",