Problem Description
Mysql database returns the following exception when querying the database: Lost connection to MySQL server during query, the specific exception information is as follows:
Traceback (most recent call last):
File "/opt/mugen/run_mugen.py", line 883, in run_testsuit
env = get_env(testsuit_name)
File "/opt/mugen/run_mugen.py", line 751, in get_env
row = session.query(Testsuit).filter(Testsuit.name == testsuit_name).first()
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/orm/query.py", line 2752, in first
return self.limit(1)._iter().first() # type: ignore
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/orm/query.py", line 2855, in _iter
result: Union[ScalarResult[_T], Result[_T]] = self.session.execute(
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/orm/session.py", line 2229, in execute
return self._execute_internal(
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/orm/session.py", line 2114, in _execute_internal
conn = self._connection_for_bind(bind)
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/orm/session.py", line 1981, in _connection_for_bind
return trans._connection_for_bind(engine, execution_options)
File "<string>", line 2, in _connection_for_bind
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/orm/state_changes.py", line 137, in _go
ret_value = fn(self, *arg, **kw)
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/orm/session.py", line 1108, in _connection_for_bind
conn = bind.connect()
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 3251, in connect
return self._connection_cls(self)
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 147, in __init__
Connection._handle_dbapi_exception_noconnection(
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 2413, in _handle_dbapi_exception_noconnection
raise sqlalchemy_exception.with_traceback(exc_info[2]) from e
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 145, in __init__
self._dbapi_connection = engine.raw_connection()
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 3275, in raw_connection
return self.pool.connect()
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 455, in connect
return _ConnectionFairy._checkout(self)
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 1271, in _checkout
fairy = _ConnectionRecord.checkout(pool)
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 725, in checkout
rec._checkin_failed(err, _fairy_was_created=False)
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/util/langhelpers.py", line 147, in __exit__
raise exc_value.with_traceback(exc_tb)
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 722, in checkout
dbapi_connection = rec.get_connection()
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 842, in get_connection
self.__connect()
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 906, in __connect
pool.logger.debug("Error on connect(): %s", e)
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/util/langhelpers.py", line 147, in __exit__
raise exc_value.with_traceback(exc_tb)
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 901, in __connect
self.dbapi_connection = connection = pool._invoke_creator(self)
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/engine/create.py", line 640, in connect
return dialect.connect(*cargs, **cparams)
File "/usr/local/python3/lib/python3.9/site-packages/sqlalchemy/engine/default.py", line 580, in connect
return self.loaded_dbapi.connect(*cargs, **cparams)
File "/usr/local/python3/lib/python3.9/site-packages/pymysql/connections.py", line 353, in __init__
self.connect()
File "/usr/local/python3/lib/python3.9/site-packages/pymysql/connections.py", line 633, in connect
self._request_authentication()
File "/usr/local/python3/lib/python3.9/site-packages/pymysql/connections.py", line 907, in _request_authentication
auth_packet = self._read_packet()
File "/usr/local/python3/lib/python3.9/site-packages/pymysql/connections.py", line 692, in _read_packet
packet_header = self._read_bytes(4)
File "/usr/local/python3/lib/python3.9/site-packages/pymysql/connections.py", line 748, in _read_bytes
raise err.OperationalError(
sqlalchemy.exc.OperationalError: (pymysql.err.OperationalError) (2013, 'Lost connection to MySQL server during query')
Solution:
1. View the values of the following variables in the database
You can see that the net_read_timeout and net_write_timeout here are 30 and 60 seconds respectively. First, modify these two parameters to a larger value. For example, modify it to 300 and 900. As shown below, what needs to be noted here is that the global and session levels need to be set separately when modifying, and then it will take effect.
