Print dataset scan only if RANK in (-1, 0) (ultralytics#7337)

* Print dataset scan only `if RANK in (-1, 0)`

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

train.py

@@ -316,7 +316,7 @@ def train(hyp, opt, device, callbacks):  # hyp is path/to/hyp.yaml or hyp dictio
             train_loader.sampler.set_epoch(epoch)
         pbar = enumerate(train_loader)
         LOGGER.info(('\n' + '%10s' * 7) % ('Epoch', 'gpu_mem', 'box', 'obj', 'cls', 'labels', 'img_size'))
-        if RANK in [-1, 0]:
+        if RANK in (-1, 0):
             pbar = tqdm(pbar, total=nb, bar_format='{l_bar}{bar:10}{r_bar}{bar:-10b}')  # progress bar
         optimizer.zero_grad()
         for i, (imgs, targets, paths, _) in pbar:  # batch -------------------------------------------------------------
@@ -365,7 +365,7 @@ def train(hyp, opt, device, callbacks):  # hyp is path/to/hyp.yaml or hyp dictio
                 last_opt_step = ni
 
             # Log
-            if RANK in [-1, 0]:
+            if RANK in (-1, 0):
                 mloss = (mloss * i + loss_items) / (i + 1)  # update mean losses
                 mem = f'{torch.cuda.memory_reserved() / 1E9 if torch.cuda.is_available() else 0:.3g}G'  # (GB)
                 pbar.set_description(('%10s' * 2 + '%10.4g' * 5) %
@@ -379,7 +379,7 @@ def train(hyp, opt, device, callbacks):  # hyp is path/to/hyp.yaml or hyp dictio
         lr = [x['lr'] for x in optimizer.param_groups]  # for loggers
         scheduler.step()
 
-        if RANK in [-1, 0]:
+        if RANK in (-1, 0):
             # mAP
             callbacks.run('on_train_epoch_end', epoch=epoch)
             ema.update_attr(model, include=['yaml', 'nc', 'hyp', 'names', 'stride', 'class_weights'])
@@ -440,7 +440,7 @@ def train(hyp, opt, device, callbacks):  # hyp is path/to/hyp.yaml or hyp dictio
 
         # end epoch ----------------------------------------------------------------------------------------------------
     # end training -----------------------------------------------------------------------------------------------------
-    if RANK in [-1, 0]:
+    if RANK in (-1, 0):
         LOGGER.info(f'\n{epoch - start_epoch + 1} epochs completed in {(time.time() - t0) / 3600:.3f} hours.')
         for f in last, best:
             if f.exists():
@@ -518,7 +518,7 @@ def parse_opt(known=False):
 
 def main(opt, callbacks=Callbacks()):
     # Checks
-    if RANK in [-1, 0]:
+    if RANK in (-1, 0):
         print_args(vars(opt))
         check_git_status()
         check_requirements(exclude=['thop'])

utils/datasets.py

@@ -36,6 +36,7 @@
 IMG_FORMATS = 'bmp', 'dng', 'jpeg', 'jpg', 'mpo', 'png', 'tif', 'tiff', 'webp'  # include image suffixes
 VID_FORMATS = 'asf', 'avi', 'gif', 'm4v', 'mkv', 'mov', 'mp4', 'mpeg', 'mpg', 'ts', 'wmv'  # include video suffixes
 BAR_FORMAT = '{l_bar}{bar:10}{r_bar}{bar:-10b}'  # tqdm bar format
+LOCAL_RANK = int(os.getenv('LOCAL_RANK', -1))  # https://pytorch.org/docs/stable/elastic/run.html
 
 # Get orientation exif tag
 for orientation in ExifTags.TAGS.keys():
@@ -454,7 +455,7 @@ def __init__(self,
 
         # Display cache
         nf, nm, ne, nc, n = cache.pop('results')  # found, missing, empty, corrupt, total
-        if exists:
+        if exists and LOCAL_RANK in (-1, 0):
             d = f"Scanning '{cache_path}' images and labels... {nf} found, {nm} missing, {ne} empty, {nc} corrupt"
             tqdm(None, desc=prefix + d, total=n, initial=n, bar_format=BAR_FORMAT)  # display cache results
             if cache['msgs']: