code: def test_ray_start_head_block_and_signals(
      configure_lang, monkeypatch, tmp_path, cleanup_ray
  ):
      """Test `ray start` with `--block` as heads and workers and signal handles"""
  
      monkeypatch.setenv(
          "RAY_USAGE_STATS_CONFIG_PATH", str(tmp_path / "config.json")
      )
      runner = CliRunner(env={"RAY_USAGE_STATS_PROMPT_ENABLED": "0"})
  
      head_parent_conn, head_child_conn = mp.Pipe()
  
      # Run `ray start --block --head` in another process and blocks
      head_proc = mp.Process(
          target=_start_ray_and_block,
          kwargs={
              "runner": runner,
              "child_conn": head_child_conn,
              "as_head": True,
          },
      )
      head_proc._start_method = "spawn"
  
      # Run
      head_proc.start()
  
      # Give it some time to start various subprocesses and `ray stop`
      # A smaller interval seems to cause occasional failure as the head process
      # was stopped too early before spawning all the subprocesses.
      time.sleep(5)
  
      # Terminate some of the children process
      children = psutil.Process(head_proc.pid).children()
  
      # Terminate everyone other than GCS
      # NOTE(rickyyx): The choice of picking GCS is arbitrary.
      gcs_proc = None
      for child in children:
          if "gcs_server" in child.name():
              gcs_proc = child
              continue
          child.terminate()
          child.wait(5)
  
          if not head_proc.is_alive():
              # NOTE(rickyyx): call recv() here is safe since the process
              # is guaranteed to be terminated.
              _fail_if_false(
                  False,
                  head_parent_conn.recv(),
                  (
                      "`ray start --head --block` should not exit"
                      f"({head_proc.exitcode}) when a subprocess is "
                      "terminated with SIGTERM."
                  ),
              )
  
      # Kill the GCS last should unblock the CLI
      if gcs_proc:
          gcs_proc.kill()
          gcs_proc.wait(10)
  
      # NOTE(rickyyx): The wait here is needed for the `head_proc`
      # process to exit
      head_proc.join(5)
  
      # Process with "--block" should be dead with a subprocess killed
      if head_proc.is_alive() or head_proc.exitcode == 0:
          # NOTE(rickyyx): call recv() here is safe since the process
          # is guaranteed to be terminated thus invocation is non-blocking.
          _fail_if_false(
              False,
              head_parent_conn.recv()
              if not head_proc.is_alive()
              else "still alive",
              (
                  "Head process should have exited with errors when one of"
                  f" subprocesses killed. But exited={head_proc.exitcode}"
              ),
          )
  
imports: import glob
  import multiprocessing
  import multiprocessing.connection
  import os
  import re
  import sys
  import tempfile
  import time
  import uuid
  from contextlib import contextmanager
  from pathlib import Path
  from typing import Optional
  from unittest.mock import MagicMock, patch
  import moto
  import pytest
  from click.testing import CliRunner
  from moto import mock_ec2, mock_iam
  from testfixtures import Replacer
  from testfixtures.popen import MockPopen, PopenBehaviour
  import ray
  import ray.autoscaler._private.aws.config
  import ray.autoscaler._private.constants
  import ray._private.ray_constants
  import ray.scripts.scripts
  from ray._private.test_utils import wait_for_condition
  from ray.cluster_utils import cluster_not_supported
  from ray.util.state import list_nodes
  import psutil
label_desc: Use image node_id 19 for calling a global function with example usage: test_ray_start_head_block_and_signals(configure_lang, monkeypatch, tmp_path, cleanup_ray) without return types