Fix: optimize save ckpt function

scripts/train_voxcpm_finetune.py

@@ -603,7 +603,7 @@ def save_checkpoint(model, optimizer, scheduler, save_dir: Path, step: int, pret
     import shutil
     
     save_dir.mkdir(parents=True, exist_ok=True)
-    tag = "latest" if step == 0 else f"step_{step:07d}"
+    tag = f"step_{step:07d}"
     folder = save_dir / tag
     folder.mkdir(parents=True, exist_ok=True)
     
@@ -649,28 +649,14 @@ def save_checkpoint(model, optimizer, scheduler, save_dir: Path, step: int, pret
     torch.save(optimizer.state_dict(), folder / "optimizer.pth")
     torch.save(scheduler.state_dict(), folder / "scheduler.pth")
 
-    # Update (or create) a `latest` symlink pointing to the most recent checkpoint folder
+    # Update (or create) a `latest` folder by copying the most recent checkpoint
     latest_link = save_dir / "latest"
     try:
-        if latest_link.exists() or latest_link.is_symlink():
-            # remove existing link or directory
-            if latest_link.is_dir() and not latest_link.is_symlink():
-                shutil.rmtree(latest_link)
-            else:
-                latest_link.unlink()
-        # Create a symlink pointing to the new folder
-        os.symlink(str(folder), str(latest_link))
+        if latest_link.exists():
+            shutil.rmtree(latest_link)
+        shutil.copytree(folder, latest_link)
     except Exception:
-        # If symlink creation fails (e.g., on Windows or permission issues), fall back to copying
-        try:
-            if latest_link.exists():
-                if latest_link.is_dir():
-                    shutil.rmtree(latest_link)
-                else:
-                    latest_link.unlink()
-            shutil.copytree(folder, latest_link)
-        except Exception:
-            print(f"Warning: failed to update latest checkpoint link at {latest_link}", file=sys.stderr)
+        print(f"Warning: failed to update latest checkpoint at {latest_link}", file=sys.stderr)
 
 
 if __name__ == "__main__":