code: def test_deploy_application_unhealthy(serve_instance):
      """Test deploying an application that becomes unhealthy."""
  
      @ray.remote
      class Event:
          def __init__(self):
              self.is_set = False
  
          def set(self):
              self.is_set = True
  
          def is_set(self):
              return self.is_set
  
      event = Event.remote()
  
      @serve.deployment(
          health_check_period_s=1, health_check_timeout_s=3
      )
      class Model:
          def __call__(self):
              return "hello world"
  
          def check_health(self):
              if ray.get(event.is_set.remote()):
                  raise RuntimeError("Intentionally failing.")
  
      handle = serve.run(Model.bind(), name="app")
      assert handle.remote().result() == "hello world"
      assert (
          serve.status().applications["app"].status
          == ApplicationStatus.RUNNING
      )
  
      # When a deployment becomes unhealthy, application should transition -> UNHEALTHY
      event.set.remote()
      wait_for_condition(
          lambda: serve.status().applications["app"].status
          == ApplicationStatus.UNHEALTHY
      )
  
      # Check that application stays unhealthy
      for _ in range(10):
          assert (
              serve.status().applications["app"].status
              == ApplicationStatus.UNHEALTHY
          )
          time.sleep(0.1)
  
      # At least 10 control loop iterations should have passed. Check that
      # the logs from application state manager notifying about unhealthy
      # deployments doesn't spam, they should get printed only once.
      controller_pid = [
          actor["pid"]
          for actor in list_actors()
          if actor["name"] == "SERVE_CONTROLLER_ACTOR"
      ][0]
      controller_log_file_name = get_component_log_file_name(
          "controller",
          controller_pid,
          component_type=None,
          suffix=".log",
      )
      controller_log_path = os.path.join(
          get_serve_logs_dir(), controller_log_file_name
      )
      with open(controller_log_path, "r") as f:
          s = f.read()
          assert (
              s.count("The deployments ['Model'] are UNHEALTHY.") <= 1
          )
  
imports: import functools
  import os
  import sys
  import threading
  import time
  from concurrent.futures.thread import ThreadPoolExecutor
  from typing import Dict
  import pytest
  import requests
  import ray
  from ray import serve
  from ray._private.pydantic_compat import ValidationError
  from ray._private.test_utils import SignalActor, wait_for_condition
  from ray.serve._private.common import ApplicationStatus
  from ray.serve._private.logging_utils import get_component_log_file_name, get_serve_logs_dir
  from ray.util.state import list_actors
label_desc: Use image node_id 7 for calling a global function with example usage: test_deploy_application_unhealthy(serve_instance) and returns: self, str