code: def _maybe_launch_index_impl_thread(self):
      
      # Try to acquire the lock for computing index_impl(), without blocking.
      if self._index_impl_lock.acquire(False):
        # We got the lock. Start the thread, which will unlock the lock when done.
        self._index_impl_thread = threading.Thread(
            target=self._async_index_impl,
            name='TextPluginIndexImplThread')
        self._index_impl_thread.start()
docs: Attempts to launch a thread to compute index_impl().
  
      This may not launch a new thread if one is already running to compute
      index_impl(); in that case, this function is a no-op.