code: def testGroups(self, num_groups):
      lock = lock_util.GroupLock(num_groups)
      num_threads = 10
      finished = set()
  
      def thread_fn(thread_id):
          time.sleep(random.random() * 0.1)
          group_id = thread_id % num_groups
          with lock.group(group_id):
              time.sleep(random.random() * 0.1)
              self.assertGreater(lock._group_member_counts[group_id], 0)
              for g, c in enumerate(lock._group_member_counts):
                  if g != group_id:
                      self.assertEqual(0, c)
              finished.add(thread_id)
  
      threads = [
          self.checkedThread(target=thread_fn, args=(i,))
          for i in range(num_threads)
      ]
  
      for i in range(num_threads):
          threads[i].start()
      for i in range(num_threads):
          threads[i].join()
  
      self.assertEqual(set(range(num_threads)), finished)
  
file_path: tensorflow/tensorflow/python/util/lock_util_test.py
imports: import random
  import time
  from absl.testing import parameterized
  from tensorflow.python.platform import test
  from tensorflow.python.util import lock_util
label_desc: Use image node_id 1 for calling the GroupLockTest obj's underlying member method code with example usage: obj.testGroups(num_groups) without return types