Database connection was found disconnected; reconnecting: DBConnectionError

[men]

openstack version:queens
neutron-server and glance-api service log:

2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines [req-d79c92f7-9fe7-49fa-9fac-4e9e34c6b01e - - - - -] Database connection was found disconnected; reconnecting: DBConnectionError: (pymysql.err.OperationalError) (2013, 'Lost connection to MySQL server during query') [SQL: u'SELECT 1'] (Background on this error at: http://sqlalche.me/e/e3q8)
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines Traceback (most recent call last):
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines File "/usr/lib/python2.7/site-packages/oslo_db/sqlalchemy/engines.py", line 73, in _connect_ping_listener
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines connection.scalar(select([1]))
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line 880, in scalar
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines return self.execute(object, *multiparams, **params).scalar()
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line 948, in execute
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines return meth(self, multiparams, params)
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines File "/usr/lib64/python2.7/site-packages/sqlalchemy/sql/elements.py", line 269, in _execute_on_connection
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines return connection._execute_clauseelement(self, multiparams, params)
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line 1060, in _execute_clauseelement
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines compiled_sql, distilled_params
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line 1200, in _execute_context
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines context)
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line 1409, in _handle_dbapi_exception
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines util.raise_from_cause(newraise, exc_info)
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines File "/usr/lib64/python2.7/site-packages/sqlalchemy/util/compat.py", line 203, in raise_from_cause
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines reraise(type(exception), exception, tb=exc_tb, cause=cause)
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line 1193, in _execute_context
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines context)
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/default.py", line 507, in do_execute
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines cursor.execute(statement, parameters)
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines File "/usr/lib/python2.7/site-packages/pymysql/cursors.py", line 166, in execute
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines result = self._query(query)
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines File "/usr/lib/python2.7/site-packages/pymysql/cursors.py", line 322, in _query
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines conn.query(q)
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines File "/usr/lib/python2.7/site-packages/pymysql/connections.py", line 856, in query
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines self._affected_rows = self._read_query_result(unbuffered=unbuffered)
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines File "/usr/lib/python2.7/site-packages/pymysql/connections.py", line 1057, in _read_query_result
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines result.read()
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines File "/usr/lib/python2.7/site-packages/pymysql/connections.py", line 1340, in read
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines first_packet = self.connection._read_packet()
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines File "/usr/lib/python2.7/site-packages/pymysql/connections.py", line 987, in _read_packet
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines packet_header = self._read_bytes(4)
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines File "/usr/lib/python2.7/site-packages/pymysql/connections.py", line 1033, in _read_bytes
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines CR.CR_SERVER_LOST, "Lost connection to MySQL server during query")
2018-06-14 18:51:55.045 2675 ERROR oslo_db.sqlalchemy.engines DBConnectionError: (pymysql.err.OperationalError) (2013, 'Lost connection to MySQL server during query') [SQL: u'SELECT 1'] (Background on this error at: http://sqlalche.me/e/e3q8)

[Brian Haley (brian-haley)]

Did neutron-server recover and continue? Transient failures can happen and aren't necessarily a bug.

[men (keyi)]

Yes, failures do not continue to occur, but it is not clear why this happened

[Slawek Kaplonski (slaweq)]

IMO it looks like some network issue or something like that. I don't think that it's Neutron bug.

[men (keyi)]

Installing OpenStack Q Documentation Many people now have this kind of error message, although it does not affect what

[Slawek Kaplonski (slaweq)]

Did You check if You can connect to mysql server manually in same time when You had this issue?
Of course, You should try to connect to Your db node from same server where neutron-server process is running and try to login to mysql with same credentials. If that connection works for You then it might be something in neutron or sqlalchemy code maybe. If this not works, problem is probably somewhere in Your deployment.

[David Espinel (dafespinelsa)]

Having the same error log when installing devstack queens

[men (keyi)]

HI Slawek Kaplonski :
      The number of mariadb connections is set to 4096 and the connection timeout is set to 30 seconds. The problem is still.There is an error message but there is no impact now, I don't know why this problem occurs.

[Launchpad Janitor (janitor)]

[Expired for neutron because there has been no activity for 60 days.]