Update requirements.txt to comment tensorboard (#11362)

* Update requirements.txt comment tensorboard

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

* Make tensorboard optional

* Update __init__.py

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

---------

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

requirements.txt

@@ -18,7 +18,7 @@ tqdm>=4.64.0
 # protobuf<=3.20.1  # https://github.com/ultralytics/yolov5/issues/8012
 
 # Logging ---------------------------------------------------------------------
-tensorboard>=2.4.1
+# tensorboard>=2.4.1
 # clearml>=1.2.0
 # comet
 

utils/loggers/__init__.py

@@ -9,7 +9,6 @@ from pathlib import Path
 
 import pkg_resources as pkg
 import torch
-from torch.utils.tensorboard import SummaryWriter
 
 from utils.general import LOGGER, colorstr, cv2
 from utils.loggers.clearml.clearml_utils import ClearmlLogger
@@ -20,6 +19,11 @@ from utils.torch_utils import de_parallel
 LOGGERS = ('csv', 'tb', 'wandb', 'clearml', 'comet')  # *.csv, TensorBoard, Weights & Biases, ClearML
 RANK = int(os.getenv('RANK', -1))
 
+try:
+    from torch.utils.tensorboard import SummaryWriter
+except ImportError:
+    SummaryWriter = lambda *args: None  # None = SummaryWriter(str)
+
 try:
     import wandb