code: def test_ray_init(monkeypatch, shutdown_only):
      def getpid(args):
          return os.getpid()
  
      def check_pool_size(pool, size):
          args = [tuple() for _ in range(size)]
          assert len(set(pool.map(getpid, args))) == size
  
      # Check that starting a pool starts ray if not initialized.
      pool = Pool(processes=2)
      assert ray.is_initialized()
      assert int(ray.cluster_resources()["CPU"]) == 2
      check_pool_size(pool, 2)
      pool.terminate()
      pool.join()
      ray.shutdown()
  
      # Set up the cluster id so that gcs is talking with a different
      # storage prefix
      monkeypatch.setenv(
          "RAY_external_storage_namespace", "new_cluster"
      )
      ray._raylet.Config.initialize("")
  
      # Check that starting a pool doesn't affect ray if there is a local
      # ray cluster running.
      ray.init(num_cpus=3)
      assert ray.is_initialized()
      pool = Pool(processes=2)
      assert int(ray.cluster_resources()["CPU"]) == 3
      check_pool_size(pool, 2)
      pool.terminate()
      pool.join()
      ray.shutdown()
  
      # Check that trying to start a pool on an existing ray cluster throws an
      # error if there aren't enough CPUs for the number of processes.
      ray.init(num_cpus=1)
      assert ray.is_initialized()
      with pytest.raises(ValueError):
          Pool(processes=2)
      assert int(ray.cluster_resources()["CPU"]) == 1
      ray.shutdown()
  
imports: import os
  import sys
  import platform
  import pytest
  import tempfile
  import time
  import random
  from collections import defaultdict
  import queue
  import math
  import ray
  from ray._private.test_utils import SignalActor
  from ray.util.multiprocessing import Pool, TimeoutError, JoinableQueue
  from ray.util.joblib import register_ray
  from joblib import parallel_backend, Parallel, delayed
label_desc: Use image node_id 7 for calling a global function with example usage: test_ray_init(monkeypatch, shutdown_only) and returns: os