code: def test_checkpoint(self):
      ds = datasets.SyntheticDataset(32, 2000, 400, 500)
      k = 10
      index = faiss.index_factory(ds.d, "IVF64,SQ8")
      index.train(ds.get_train())
      index.add(ds.get_database())
      index.nprobe = 5
      Dref, Iref = index.search(ds.get_queries(), k)
  
      checkpoint = tempfile.mktemp()
      try:
          # First big batch search
          try:
              Dnew, Inew = big_batch_search.big_batch_search(
                  index,
                  ds.get_queries(),
                  k,
                  method="knn_function",
                  threaded=2,
                  checkpoint=checkpoint,
                  checkpoint_freq=0.1,
                  crash_at=20,
              )
          except ZeroDivisionError:
              pass
          else:
              self.assertFalse("should have crashed")
          # Second big batch search
          Dnew, Inew = big_batch_search.big_batch_search(
              index,
              ds.get_queries(),
              k,
              method="knn_function",
              threaded=2,
              checkpoint=checkpoint,
              checkpoint_freq=5,
          )
          self.assertLess((Inew != Iref).sum() / Iref.size, 1e-4)
          np.testing.assert_almost_equal(Dnew, Dref, decimal=4)
      finally:
          if os.path.exists(checkpoint):
              os.unlink(checkpoint)
  
imports: import faiss
  import unittest
  import numpy
  import platform
  import os
  import random
  import tempfile
  from faiss.contrib import datasets
  from faiss.contrib import inspect_tools
  from faiss.contrib import evaluation
  from faiss.contrib import ivf_tools
  from faiss.contrib import clustering
  from faiss.contrib import big_batch_search
  from common_faiss_tests import get_dataset_2
label_desc: Use image node_id 6 for calling the TestBigBatchSearch obj's underlying member method code with example usage: obj.test_checkpoint() without return types