add random shuffle in PKSampler

ppcls/data/dataloader/pk_sampler.py

@@ -18,7 +18,9 @@ from __future__ import division
 from collections import defaultdict
 
 import numpy as np
+import paddle.distributed as dist
 from paddle.io import DistributedBatchSampler
+
 from ppcls.utils import logger
 
 
@@ -94,6 +96,12 @@ class PKSampler(DistributedBatchSampler):
                     format(diff))
 
     def __iter__(self):
+        # shuffle manually, same as DistributedBatchSampler.__iter__
+        if self.shuffle:
+            np.random.RandomState(self.epoch + dist.get_rank()).shuffle(
+                self.label_list)
+            self.epoch += 1
+
         label_per_batch = self.batch_size // self.sample_per_id
         for _ in range(len(self)):
             batch_index = []