fix

data_utils.py

@@ -285,6 +285,8 @@ class DistributedBucketSampler(torch.utils.data.distributed.DistributedSampler):
         for i in range(len(self.buckets)):
             bucket = self.buckets[i]
             len_bucket = len(bucket)
+            if (len_bucket == 0):
+                continue
             ids_bucket = indices[i]
             num_samples_bucket = self.num_samples_per_bucket[i]