TensorBoard add_graph() fix (#3236)

train.py

@@ -330,9 +330,9 @@ def train(hyp, opt, device, tb_writer=None):
                 if plots and ni < 3:
                     f = save_dir / f'train_batch{ni}.jpg'  # filename
                     Thread(target=plot_images, args=(imgs, targets, paths, f), daemon=True).start()
-                    # if tb_writer:
-                    #     tb_writer.add_image(f, result, dataformats='HWC', global_step=epoch)
-                    #     tb_writer.add_graph(torch.jit.trace(model, imgs, strict=False), [])  # add model graph
+                    if tb_writer:
+                        tb_writer.add_graph(torch.jit.trace(model, imgs, strict=False), [])  # add model graph
+                        # tb_writer.add_image(f, result, dataformats='HWC', global_step=epoch)
                 elif plots and ni == 10 and wandb_logger.wandb:
                     wandb_logger.log({"Mosaics": [wandb_logger.wandb.Image(str(x), caption=x.name) for x in
                                                   save_dir.glob('train*.jpg') if x.exists()]})