code: def wait_all_done(self):
      self.barrier.wait()
  
imports: import sys
  import threading
  import pytest
  import ray
  from ray.tests.test_memory_pressure import allocate_memory, Leaker, get_additional_bytes_to_reach_memory_usage_pct, memory_usage_threshold, memory_monitor_refresh_ms
label_desc: Use image node_id 2 for calling the BarrierActor obj's underlying member method code with example usage: obj.wait_all_done() without return types