old_contents: import os
  import json
  import psutil
  from notebook.utils import url_path_join
  from notebook.base.handlers import IPythonHandler
  
  def get_metrics():
      cur_process = psutil.Process()
      all_processes = [cur_process] + cur_process.children(recursive=True)
      rss = sum([p.memory_info().rss for p in all_processes])
      return {
          'rss': rss,
          'limits': {
              'memory': int(os.environ.get('LIMIT_MEM', None))
          }
      }
  
  
  class MetricsHandler(IPythonHandler):
      def get(self):
          self.finish(json.dumps(get_metrics()))
  
  
  def setup_handlers(web_app):
      route_pattern = url_path_join(web_app.settings['base_url'], '/metrics')
      web_app.add_handlers('.*', [(route_pattern, MetricsHandler)])
  
new_contents: import os
  import json
  import psutil
  from notebook.utils import url_path_join
  from notebook.base.handlers import IPythonHandler
  
  def get_metrics():
      cur_process = psutil.Process()
      all_processes = [cur_process] + cur_process.children(recursive=True)
      rss = sum([p.memory_info().rss for p in all_processes])
      return {
          'rss': rss,
          'limits': {
              'memory': int(os.environ.get('MEM_LIMIT', None))
          }
      }
  
  
  class MetricsHandler(IPythonHandler):
      def get(self):
          self.finish(json.dumps(get_metrics()))
  
  
  def setup_handlers(web_app):
      route_pattern = url_path_join(web_app.settings['base_url'], '/metrics')
      web_app.add_handlers('.*', [(route_pattern, MetricsHandler)])
  
subject: Use final Memory limit env variable name