feat: 缓存worker内的句柄

roboimi/demos/vla_scripts/train_vla.py

@@ -139,6 +139,7 @@ def main(cfg: DictConfig):
         shuffle=True,
         num_workers=cfg.train.num_workers,
         pin_memory=(cfg.train.device != "cpu"),
+        persistent_workers=(cfg.train.num_workers > 0),
         drop_last=True  # 丢弃不完整批次以稳定训练
     )
 
@@ -150,6 +151,7 @@ def main(cfg: DictConfig):
             shuffle=False,
             num_workers=cfg.train.num_workers,
             pin_memory=(cfg.train.device != "cpu"),
+            persistent_workers=(cfg.train.num_workers > 0),
             drop_last=False
         )