diff --git a/judge/utils/iterator.py b/judge/utils/iterator.py
new file mode 100644
index 0000000000..19ca285fd3
--- /dev/null
+++ b/judge/utils/iterator.py
@@ -0,0 +1,7 @@
+from itertools import zip_longest
+
+
+def chunk(iterable, size):
+    fill = object()
+    for group in zip_longest(*[iter(iterable)] * size, fillvalue=fill):
+        yield [item for item in group if item is not fill]
diff --git a/judge/utils/tests/test_iterator.py b/judge/utils/tests/test_iterator.py
new file mode 100644
index 0000000000..30153616be
--- /dev/null
+++ b/judge/utils/tests/test_iterator.py
@@ -0,0 +1,18 @@
+import unittest
+from itertools import chain
+
+from judge.utils.iterator import chunk
+
+
+class ChunkTestCase(unittest.TestCase):
+    def test_empty(self):
+        self.assertEqual(list(chunk([], 5)), [])
+
+    def test_normal(self):
+        for size in [10, 13, 100, 200]:
+            with self.subTest(f'chunk size {size}'):
+                result = list(chunk(range(100), size))
+                self.assertEqual(list(chain(*result)), list(range(100)))
+                for part in result[:-1]:
+                    self.assertEqual(len(part), size)
+                self.assertLessEqual(len(result[-1]), size)