code: def test_stream_thread(self):
      s1 = None
  
      def f1(barrier, errors):
          global s1
          tid = barrier.wait()
          try:
              s1 = cuda.Stream()
              barrier.wait()  # until t2 starts
              s1.use()
              barrier.wait()  # until t2 uses the stream
              s1 = None
              gc.collect()
              barrier.wait()  # until t2 decrefs the stream
              assert cuda.get_current_stream() is not None
              cupy.arange(10)
              errors[tid] = False
          except Exception as e:
              print(f"error in {tid}: {e}")
  
      def f2(barrier, errors):
          global s1
          tid = barrier.wait()
          try:
              barrier.wait()  # until t1 creates the stream
              s1.use()
              barrier.wait()  # until t1 uses the stream
              s1 = None
              gc.collect()
              barrier.wait()  # until t1 decrefs the stream
              assert cuda.get_current_stream() is not None
              cupy.arange(10)
              errors[tid] = False
          except Exception as e:
              print(f"error in {tid}: {e}")
  
      barrier = threading.Barrier(2)
      errors = [True, True]
      threads = [
          threading.Thread(
              target=f1, args=(barrier, errors), daemon=True
          ),
          threading.Thread(
              target=f2, args=(barrier, errors), daemon=True
          ),
      ]
      del s1
      for t in threads:
          t.start()
      for t in threads:
          t.join()
      for err in errors:
          assert err is False
  
imports: import gc
  import threading
  import unittest
  import pytest
  import cupy
  from cupy._creation import from_data
  from cupy import cuda
  from cupy import testing
label_desc: Use image node_id 16 for calling the TestStream obj's underlying member method code with example usage: obj.test_stream_thread() without return types