apscheduler Потеряно соединение с сервером MySQL во время запроса

Я использую apscheduler для выполнения обычного задания, и у меня возникла ошибка.

«Потеряно соединение с сервером MySQL во время запроса»

Чтобы найти ответ, я пробую на нем несколько тестов и выясняю, что если моя база данных (MySQL) "wait_timeout" меньше времени интервала расписания, то возникает эта ошибка. (извините, здесь я сделал ошибку... меньше, чем...)

в тесте:

• моя работа

  scheduler.add_job (период_задания, 'интервал', минуты = 5, id = 'my_job_id')

• мои настройки базы данных

  время_ожидания = 60

• мой тестовый код

  from apscheduler.schedulers.background import BackgroundScheduler
  from flask import Flask
  app = Flask(__name__)
  
  scheduler = BackgroundScheduler({'apscheduler.jobstores.default': {
          'type': 'sqlalchemy',
          'url': 'mysql+pymysql://user:pass@url:3306/test_apscheduler?charset=utf8'
      },
          'apscheduler.executors.default': {
              'class': 'apscheduler.executors.pool:ThreadPoolExecutor',
              'max_workers': '20'
      },
          'apscheduler.executors.processpool': {
          'type': 'processpool',
          'max_workers': '5'
      },
          'apscheduler.job_defaults.coalesce': 'false',
          'apscheduler.job_defaults.max_instances': '3',
          'apscheduler.timezone': 'UTC',
      })
  
  scheduler.start()
  
  
  @app.route('/')
  def hello_world():
      scheduler.add_job(period_job, 'interval', minutes=5, id='my_job_id')
      return 'Hello World!'
  
  
  def period_job():
      print("hihi")
  
  
  if __name__ == '__main__':
      app.run()
  

общее сообщение об ошибке:

Exception in thread APScheduler:
Traceback (most recent call last):
  File "C:\Users\skuo\apshcduler\lib\site-packages\sqlalchemy\engine\base.py", line 1139, in _execute_context context)
  File "C:\Users\skuo\apshcduler\lib\site-packages\sqlalchemy\engine\default.py", line 450, in do_execute cursor.execute(statement, parameters)
  File "C:\Users\skuo\apshcduler\lib\site-packages\pymysql\cursors.py", line 158, in execute result = self._query(query)
  File "C:\Users\skuo\apshcduler\lib\site-packages\pymysql\cursors.py", line 308, in _query conn.query(q)
  File "C:\Users\skuo\apshcduler\lib\site-packages\pymysql\connections.py", line 820, in query self._affected_rows = self._read_query_result(unbuffered=unbuffered)
  File "C:\Users\skuo\apshcduler\lib\site-packages\pymysql\connections.py", line 1002, in _read_query_result result.read()
  File "C:\Users\skuo\apshcduler\lib\site-packages\pymysql\connections.py", line 1285, in read first_packet = self.connection._read_packet()
  File "C:\Users\skuo\apshcduler\lib\site-packages\pymysql\connections.py", line 946, in _read_packet packet_header = self._read_bytes(4)
  File "C:\Users\skuo\apshcduler\lib\site-packages\pymysql\connections.py", line 982, in _read_bytes 2013, "Lost connection to MySQL server during query")
pymysql.err.OperationalError: (2013, 'Lost connection to MySQL server during query')

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\Python34\lib\threading.py", line 921, in _bootstrap_inner self.run()
  File "C:\Python34\lib\threading.py", line 869, in run self._target(*self._args, **self._kwargs)
  File "C:\Users\skuo\apshcduler\lib\site-packages\apscheduler\schedulers\blocking.py", line 27, in _main_loop wait_seconds = self._process_jobs()
  File "C:\Users\skuo\apshcduler\lib\site-packages\apscheduler\schedulers\base.py", line 801, in _process_jobs for job in jobstore.get_due_jobs(now):
  File "C:\Users\skuo\apshcduler\lib\site-packages\apscheduler\jobstores\sqlalchemy.py", line 69, in get_due_jobs return self._get_jobs(self.jobs_t.c.next_run_time <= timestamp)
  File "C:\Users\skuo\apshcduler\lib\site-packages\apscheduler\jobstores\sqlalchemy.py", line 131, in _get_jobs for row in self.engine.execute(selectable):
  File "C:\Users\skuo\apshcduler\lib\site-packages\sqlalchemy\engine\base.py", line 1991, in execute return connection.execute(statement, *multiparams, **params)
  File "C:\Users\skuo\apshcduler\lib\site-packages\sqlalchemy\engine\base.py", line 914, in execute return meth(self, multiparams, params)
  File "C:\Users\skuo\apshcduler\lib\site-packages\sqlalchemy\sql\elements.py", line 323, in _execute_on_connection return connection._execute_clauseelement(self, multiparams, params)
  File "C:\Users\skuo\apshcduler\lib\site-packages\sqlalchemy\engine\base.py", line 1010, in _execute_clauseelement compiled_sql, distilled_params
  File "C:\Users\skuo\apshcduler\lib\site-packages\sqlalchemy\engine\base.py", line 1146, in _execute_context context)
  File "C:\Users\skuo\apshcduler\lib\site-packages\sqlalchemy\engine\base.py", line 1341, in _handle_dbapi_exception exc_info
  File "C:\Users\skuo\apshcduler\lib\site-packages\sqlalchemy\util\compat.py", line 200, in raise_from_cause reraise(type(exception), exception, tb=exc_tb, cause=cause)
  File "C:\Users\skuo\apshcduler\lib\site-packages\sqlalchemy\util\compat.py", line 183, in reraise raise value.with_traceback(tb)
  File "C:\Users\skuo\apshcduler\lib\site-packages\sqlalchemy\engine\base.py", line 1139, in _execute_context context)
  File "C:\Users\skuo\apshcduler\lib\site-packages\sqlalchemy\engine\default.py", line 450, in do_execute cursor.execute(statement, parameters)
  File "C:\Users\skuo\apshcduler\lib\site-packages\pymysql\cursors.py", line 158, in execute result = self._query(query)
  File "C:\Users\skuo\apshcduler\lib\site-packages\pymysql\cursors.py", line 308, in _query conn.query(q)
  File "C:\Users\skuo\apshcduler\lib\site-packages\pymysql\connections.py", line 820, in query self._affected_rows = self._read_query_result(unbuffered=unbuffered)
  File "C:\Users\skuo\apshcduler\lib\site-packages\pymysql\connections.py", line 1002, in _read_query_result result.read()
  File "C:\Users\skuo\apshcduler\lib\site-packages\pymysql\connections.py", line 1285, in read first_packet = self.connection._read_packet()
  File "C:\Users\skuo\apshcduler\lib\site-packages\pymysql\connections.py", line 946, in _read_packet packet_header = self._read_bytes(4)
  File "C:\Users\skuo\apshcduler\lib\site-packages\pymysql\connections.py", line 982, in _read_bytes 2013, "Lost connection to MySQL server during query")
sqlalchemy.exc.OperationalError: (pymysql.err.OperationalError) (2013, 'Lost connection to MySQL server during query') [SQL: 'SELECT apscheduler_jobs.id, apscheduler_jobs.job_state \nFROM apscheduler_jobs \nWHERE apscheduler_jobs.next_run_time <= %(next_run_time_1)s ORDER BY apscheduler_jobs.next_run_time'] [parameters: {'next_run_time_1': 1457445220.361246}]

кто-нибудь знает, что с этим случилось? и как это исправить?