zero-mAP fix remove torch.empty() forward pass in .train() mode (#9068)

* Fix Zero Map Issue

Signed-off-by: 0zppd <111682241+0zppd@users.noreply.github.com>

* Update __init__.py

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>

Signed-off-by: 0zppd <111682241+0zppd@users.noreply.github.com>
Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>
Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

utils/loggers/__init__.py

@@ -296,7 +296,7 @@ def log_tensorboard_graph(tb, model, imgsz=(640, 640)):
     try:
         p = next(model.parameters())  # for device, type
         imgsz = (imgsz, imgsz) if isinstance(imgsz, int) else imgsz  # expand
-        im = torch.empty((1, 3, *imgsz)).to(p.device).type_as(p)  # input image
+        im = torch.zeros((1, 3, *imgsz)).to(p.device).type_as(p)  # input image (WARNING: must be zeros, not empty)
         with warnings.catch_warnings():
             warnings.simplefilter('ignore')  # suppress jit trace warning
             tb.add_graph(torch.jit.trace(de_parallel(model), im, strict=False), [])