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[Bug 1444532] [NEW] nova-scheduler doesnt reconnect to databases when started and database is down

To: yahoo-eng-team@xxxxxxxxxxxxxxxxxxx
From: Alejandro Comisario <alejandro@xxxxxxxxxxx>
Date: Wed, 15 Apr 2015 15:20:55 -0000
Reply-to: Bug 1444532 <1444532@xxxxxxxxxxxxxxxxxx>
Sender: bounces@xxxxxxxxxxxxx
Public bug reported:

In Juno release (ubuntu packages), when you start nova-scheduler but
database is down, the service never reconnects, the stacktrace is as
follow :


AUDIT nova.service [-] Starting scheduler node (version 2014.2.2)
ERROR nova.openstack.common.threadgroup [-] (OperationalError) (2003, "Can't connect to MySQL server on '10.128.30.11' (111)") None None
TRACE nova.openstack.common.threadgroup Traceback (most recent call last):
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/openstack/common/threadgroup.py", line 125, in wait
TRACE nova.openstack.common.threadgroup     x.wait()
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/openstack/common/threadgroup.py", line 47, in wait
TRACE nova.openstack.common.threadgroup     return self.thread.wait()
TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/eventlet/greenthread.py", line 173, in wait
TRACE nova.openstack.common.threadgroup     return self._exit_event.wait()
TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/eventlet/event.py", line 121, in wait
TRACE nova.openstack.common.threadgroup     return hubs.get_hub().switch()
TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/eventlet/hubs/hub.py", line 293, in switch
TRACE nova.openstack.common.threadgroup     return self.greenlet.switch()
TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/eventlet/greenthread.py", line 212, in main
TRACE nova.openstack.common.threadgroup     result = function(*args, **kwargs)
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/openstack/common/service.py", line 490, in run_service
TRACE nova.openstack.common.threadgroup     service.start()
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/service.py", line 169, in start
TRACE nova.openstack.common.threadgroup     self.host, self.binary)
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/conductor/api.py", line 161, in service_get_by_args
TRACE nova.openstack.common.threadgroup     binary=binary, topic=None)
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/utils.py", line 949, in wrapper
TRACE nova.openstack.common.threadgroup     return func(*args, **kwargs)
TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/messaging/rpc/server.py", line 139, in inner
TRACE nova.openstack.common.threadgroup     return func(*args, **kwargs)
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/conductor/manager.py", line 279, in service_get_all_by
TRACE nova.openstack.common.threadgroup     result = self.db.service_get_by_args(context, host, binary)
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/db/api.py", line 136, in service_get_by_args
TRACE nova.openstack.common.threadgroup     return IMPL.service_get_by_args(context, host, binary)
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 125, in wrapper
TRACE nova.openstack.common.threadgroup     return f(*args, **kwargs)
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 490, in service_get_by_args
TRACE nova.openstack.common.threadgroup     result = model_query(context, models.Service).\
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 213, in model_query
TRACE nova.openstack.common.threadgroup     session = kwargs.get('session') or get_session(use_slave=use_slave)
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 101, in get_session
TRACE nova.openstack.common.threadgroup     facade = _create_facade_lazily()
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 91, in _create_facade_lazily
TRACE nova.openstack.common.threadgroup     _ENGINE_FACADE = db_session.EngineFacade.from_config(CONF)
TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/session.py", line 795, in from_config
TRACE nova.openstack.common.threadgroup     retry_interval=conf.database.retry_interval)
TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/session.py", line 711, in __init__
TRACE nova.openstack.common.threadgroup     **engine_kwargs)
TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/session.py", line 386, in create_engine
TRACE nova.openstack.common.threadgroup     connection_trace=connection_trace
TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/utils.py", line 890, in __call__
TRACE nova.openstack.common.threadgroup     self._url_from_target(target), target, arg, kw)
TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/utils.py", line 927, in _dispatch_on
TRACE nova.openstack.common.threadgroup     return self._dispatch_on_db_driver(dbname, driver, arg, kw)
TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/utils.py", line 981, in _dispatch_on_db_driver
TRACE nova.openstack.common.threadgroup     if self._invoke_fn(fn, arg, kw) is not None:
TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/utils.py", line 930, in _invoke_fn
TRACE nova.openstack.common.threadgroup     return fn(*arg, **kw)
TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/session.py", line 456, in _init_events
TRACE nova.openstack.common.threadgroup     realmode = engine.execute("SHOW VARIABLES LIKE 'sql_mode'").fetchone()
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1751, in execute
TRACE nova.openstack.common.threadgroup     connection = self.contextual_connect(close_with_result=True)
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1799, in contextual_connect
TRACE nova.openstack.common.threadgroup     self.pool.connect(),
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 338, in connect
TRACE nova.openstack.common.threadgroup     return _ConnectionFairy._checkout(self)
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 641, in _checkout
TRACE nova.openstack.common.threadgroup     fairy = _ConnectionRecord.checkout(pool)
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 440, in checkout
TRACE nova.openstack.common.threadgroup     rec = pool._do_get()
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 961, in _do_get
TRACE nova.openstack.common.threadgroup     return self._create_connection()
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 285, in _create_connection
TRACE nova.openstack.common.threadgroup     return _ConnectionRecord(self)
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 411, in __init__
TRACE nova.openstack.common.threadgroup     self.connection = self.__connect()
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 537, in __connect
TRACE nova.openstack.common.threadgroup     connection = self.__pool._creator()
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/strategies.py", line 96, in connect
TRACE nova.openstack.common.threadgroup     connection_invalidated=invalidated
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/util/compat.py", line 199, in raise_from_cause
TRACE nova.openstack.common.threadgroup     reraise(type(exception), exception, tb=exc_tb)
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/strategies.py", line 90, in connect
TRACE nova.openstack.common.threadgroup     return dialect.connect(*cargs, **cparams)
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/default.py", line 377, in connect
TRACE nova.openstack.common.threadgroup     return self.dbapi.connect(*cargs, **cparams)
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/MySQLdb/__init__.py", line 81, in Connect
TRACE nova.openstack.common.threadgroup     return Connection(*args, **kwargs)
TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/MySQLdb/connections.py", line 187, in __init__
TRACE nova.openstack.common.threadgroup     super(Connection, self).__init__(*args, **kwargs2)
TRACE nova.openstack.common.threadgroup OperationalError: (OperationalError) (2003, "Can't connect to MySQL server on '10.128.30.11' (111)") None None
TRACE nova.openstack.common.threadgroup 

That doesnt happen once nova-scheduler connects, and database is gone,
after the database is up again IT DOES reconnects, but the calls are
from different part of the code ( nova.servicegroup.drivers.db ) and
when it doesnt work its called from ( nova.openstack.common.threadgroup
), the stack when it works is as follow:


ERROR nova.servicegroup.drivers.db [-] model server went away
TRACE nova.servicegroup.drivers.db Traceback (most recent call last):
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/servicegroup/drivers/db.py", line 99, in _report_state
TRACE nova.servicegroup.drivers.db     service.service_ref, state_catalog)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/conductor/api.py", line 180, in service_update
TRACE nova.servicegroup.drivers.db     return self._manager.service_update(context, service, values)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/utils.py", line 949, in wrapper
TRACE nova.servicegroup.drivers.db     return func(*args, **kwargs)
TRACE nova.servicegroup.drivers.db   File "/usr/local/lib/python2.7/dist-packages/oslo/messaging/rpc/server.py", line 139, in inner
TRACE nova.servicegroup.drivers.db     return func(*args, **kwargs)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/conductor/manager.py", line 320, in service_update
TRACE nova.servicegroup.drivers.db     svc = self.db.service_update(context, service['id'], values)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/db/api.py", line 150, in service_update
TRACE nova.servicegroup.drivers.db     return IMPL.service_update(context, service_id, values)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 125, in wrapper
TRACE nova.servicegroup.drivers.db     return f(*args, **kwargs)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 181, in wrapped
TRACE nova.servicegroup.drivers.db     return f(*args, **kwargs)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 524, in service_update
TRACE nova.servicegroup.drivers.db     with_compute_node=False, session=session)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 424, in _service_get
TRACE nova.servicegroup.drivers.db     result = query.first()
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2341, in first
TRACE nova.servicegroup.drivers.db     ret = list(self[0:1])
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2208, in __getitem__
TRACE nova.servicegroup.drivers.db     return list(res)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2412, in __iter__
TRACE nova.servicegroup.drivers.db     return self._execute_and_instances(context)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2425, in _execute_and_instances
TRACE nova.servicegroup.drivers.db     close_with_result=True)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2416, in _connection_from_session
TRACE nova.servicegroup.drivers.db     **kw)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 854, in connection
TRACE nova.servicegroup.drivers.db     close_with_result=close_with_result)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 858, in _connection_for_bind
TRACE nova.servicegroup.drivers.db     return self.transaction._connection_for_bind(engine)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 329, in _connection_for_bind
TRACE nova.servicegroup.drivers.db     transaction = conn.begin()
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 420, in begin
TRACE nova.servicegroup.drivers.db     self.__transaction = RootTransaction(self)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1357, in __init__
TRACE nova.servicegroup.drivers.db     self.connection._begin_impl(self)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 490, in _begin_impl
TRACE nova.servicegroup.drivers.db     self.dispatch.begin(self)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/event/attr.py", line 260, in __call__
TRACE nova.servicegroup.drivers.db     fn(*args, **kw)
TRACE nova.servicegroup.drivers.db   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/session.py", line 331, in _begin_ping_listener
TRACE nova.servicegroup.drivers.db     connection.scalar(select([1]))
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 659, in scalar
TRACE nova.servicegroup.drivers.db     return self.execute(object, *multiparams, **params).scalar()
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 729, in execute
TRACE nova.servicegroup.drivers.db     return meth(self, multiparams, params)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/sql/elements.py", line 321, in _execute_on_connection
TRACE nova.servicegroup.drivers.db     return connection._execute_clauseelement(self, multiparams, params)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 826, in _execute_clauseelement
TRACE nova.servicegroup.drivers.db     compiled_sql, distilled_params
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 893, in _execute_context
TRACE nova.servicegroup.drivers.db     None, None)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1169, in _handle_dbapi_exception
TRACE nova.servicegroup.drivers.db     dbapi_conn_wrapper = self.connection
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 236, in connection
TRACE nova.servicegroup.drivers.db     return self._revalidate_connection()
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 244, in _revalidate_connection
TRACE nova.servicegroup.drivers.db     self.__connection = self.engine.raw_connection()
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1848, in raw_connection
TRACE nova.servicegroup.drivers.db     return self.pool.unique_connection()
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 280, in unique_connection
TRACE nova.servicegroup.drivers.db     return _ConnectionFairy._checkout(self)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 641, in _checkout
TRACE nova.servicegroup.drivers.db     fairy = _ConnectionRecord.checkout(pool)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 442, in checkout
TRACE nova.servicegroup.drivers.db     dbapi_connection = rec.get_connection()
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 505, in get_connection
TRACE nova.servicegroup.drivers.db     self.connection = self.__connect()
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 537, in __connect
TRACE nova.servicegroup.drivers.db     connection = self.__pool._creator()
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/strategies.py", line 96, in connect
TRACE nova.servicegroup.drivers.db     connection_invalidated=invalidated
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/util/compat.py", line 199, in raise_from_cause
TRACE nova.servicegroup.drivers.db     reraise(type(exception), exception, tb=exc_tb)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/strategies.py", line 90, in connect
TRACE nova.servicegroup.drivers.db     return dialect.connect(*cargs, **cparams)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/default.py", line 377, in connect
TRACE nova.servicegroup.drivers.db     return self.dbapi.connect(*cargs, **cparams)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/MySQLdb/__init__.py", line 81, in Connect
TRACE nova.servicegroup.drivers.db     return Connection(*args, **kwargs)
TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/MySQLdb/connections.py", line 187, in __init__
TRACE nova.servicegroup.drivers.db     super(Connection, self).__init__(*args, **kwargs2)
TRACE nova.servicegroup.drivers.db OperationalError: (OperationalError) (2003, "Can't connect to MySQL server on '10.128.30.11' (111)") None None
TRACE nova.servicegroup.drivers.db

** Affects: nova
     Importance: Undecided
         Status: New


** Tags: juno nova nova-scheduler

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https://bugs.launchpad.net/bugs/1444532

Title:
  nova-scheduler doesnt reconnect to databases when started and database
  is down

Status in OpenStack Compute (Nova):
  New

Bug description:
  In Juno release (ubuntu packages), when you start nova-scheduler but
  database is down, the service never reconnects, the stacktrace is as
  follow :

  
  AUDIT nova.service [-] Starting scheduler node (version 2014.2.2)
  ERROR nova.openstack.common.threadgroup [-] (OperationalError) (2003, "Can't connect to MySQL server on '10.128.30.11' (111)") None None
  TRACE nova.openstack.common.threadgroup Traceback (most recent call last):
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/openstack/common/threadgroup.py", line 125, in wait
  TRACE nova.openstack.common.threadgroup     x.wait()
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/openstack/common/threadgroup.py", line 47, in wait
  TRACE nova.openstack.common.threadgroup     return self.thread.wait()
  TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/eventlet/greenthread.py", line 173, in wait
  TRACE nova.openstack.common.threadgroup     return self._exit_event.wait()
  TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/eventlet/event.py", line 121, in wait
  TRACE nova.openstack.common.threadgroup     return hubs.get_hub().switch()
  TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/eventlet/hubs/hub.py", line 293, in switch
  TRACE nova.openstack.common.threadgroup     return self.greenlet.switch()
  TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/eventlet/greenthread.py", line 212, in main
  TRACE nova.openstack.common.threadgroup     result = function(*args, **kwargs)
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/openstack/common/service.py", line 490, in run_service
  TRACE nova.openstack.common.threadgroup     service.start()
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/service.py", line 169, in start
  TRACE nova.openstack.common.threadgroup     self.host, self.binary)
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/conductor/api.py", line 161, in service_get_by_args
  TRACE nova.openstack.common.threadgroup     binary=binary, topic=None)
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/utils.py", line 949, in wrapper
  TRACE nova.openstack.common.threadgroup     return func(*args, **kwargs)
  TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/messaging/rpc/server.py", line 139, in inner
  TRACE nova.openstack.common.threadgroup     return func(*args, **kwargs)
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/conductor/manager.py", line 279, in service_get_all_by
  TRACE nova.openstack.common.threadgroup     result = self.db.service_get_by_args(context, host, binary)
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/db/api.py", line 136, in service_get_by_args
  TRACE nova.openstack.common.threadgroup     return IMPL.service_get_by_args(context, host, binary)
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 125, in wrapper
  TRACE nova.openstack.common.threadgroup     return f(*args, **kwargs)
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 490, in service_get_by_args
  TRACE nova.openstack.common.threadgroup     result = model_query(context, models.Service).\
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 213, in model_query
  TRACE nova.openstack.common.threadgroup     session = kwargs.get('session') or get_session(use_slave=use_slave)
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 101, in get_session
  TRACE nova.openstack.common.threadgroup     facade = _create_facade_lazily()
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 91, in _create_facade_lazily
  TRACE nova.openstack.common.threadgroup     _ENGINE_FACADE = db_session.EngineFacade.from_config(CONF)
  TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/session.py", line 795, in from_config
  TRACE nova.openstack.common.threadgroup     retry_interval=conf.database.retry_interval)
  TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/session.py", line 711, in __init__
  TRACE nova.openstack.common.threadgroup     **engine_kwargs)
  TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/session.py", line 386, in create_engine
  TRACE nova.openstack.common.threadgroup     connection_trace=connection_trace
  TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/utils.py", line 890, in __call__
  TRACE nova.openstack.common.threadgroup     self._url_from_target(target), target, arg, kw)
  TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/utils.py", line 927, in _dispatch_on
  TRACE nova.openstack.common.threadgroup     return self._dispatch_on_db_driver(dbname, driver, arg, kw)
  TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/utils.py", line 981, in _dispatch_on_db_driver
  TRACE nova.openstack.common.threadgroup     if self._invoke_fn(fn, arg, kw) is not None:
  TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/utils.py", line 930, in _invoke_fn
  TRACE nova.openstack.common.threadgroup     return fn(*arg, **kw)
  TRACE nova.openstack.common.threadgroup   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/session.py", line 456, in _init_events
  TRACE nova.openstack.common.threadgroup     realmode = engine.execute("SHOW VARIABLES LIKE 'sql_mode'").fetchone()
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1751, in execute
  TRACE nova.openstack.common.threadgroup     connection = self.contextual_connect(close_with_result=True)
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1799, in contextual_connect
  TRACE nova.openstack.common.threadgroup     self.pool.connect(),
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 338, in connect
  TRACE nova.openstack.common.threadgroup     return _ConnectionFairy._checkout(self)
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 641, in _checkout
  TRACE nova.openstack.common.threadgroup     fairy = _ConnectionRecord.checkout(pool)
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 440, in checkout
  TRACE nova.openstack.common.threadgroup     rec = pool._do_get()
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 961, in _do_get
  TRACE nova.openstack.common.threadgroup     return self._create_connection()
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 285, in _create_connection
  TRACE nova.openstack.common.threadgroup     return _ConnectionRecord(self)
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 411, in __init__
  TRACE nova.openstack.common.threadgroup     self.connection = self.__connect()
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 537, in __connect
  TRACE nova.openstack.common.threadgroup     connection = self.__pool._creator()
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/strategies.py", line 96, in connect
  TRACE nova.openstack.common.threadgroup     connection_invalidated=invalidated
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/util/compat.py", line 199, in raise_from_cause
  TRACE nova.openstack.common.threadgroup     reraise(type(exception), exception, tb=exc_tb)
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/strategies.py", line 90, in connect
  TRACE nova.openstack.common.threadgroup     return dialect.connect(*cargs, **cparams)
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/default.py", line 377, in connect
  TRACE nova.openstack.common.threadgroup     return self.dbapi.connect(*cargs, **cparams)
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/MySQLdb/__init__.py", line 81, in Connect
  TRACE nova.openstack.common.threadgroup     return Connection(*args, **kwargs)
  TRACE nova.openstack.common.threadgroup   File "/usr/lib/python2.7/dist-packages/MySQLdb/connections.py", line 187, in __init__
  TRACE nova.openstack.common.threadgroup     super(Connection, self).__init__(*args, **kwargs2)
  TRACE nova.openstack.common.threadgroup OperationalError: (OperationalError) (2003, "Can't connect to MySQL server on '10.128.30.11' (111)") None None
  TRACE nova.openstack.common.threadgroup 

  That doesnt happen once nova-scheduler connects, and database is gone,
  after the database is up again IT DOES reconnects, but the calls are
  from different part of the code ( nova.servicegroup.drivers.db ) and
  when it doesnt work its called from (
  nova.openstack.common.threadgroup ), the stack when it works is as
  follow:

  
  ERROR nova.servicegroup.drivers.db [-] model server went away
  TRACE nova.servicegroup.drivers.db Traceback (most recent call last):
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/servicegroup/drivers/db.py", line 99, in _report_state
  TRACE nova.servicegroup.drivers.db     service.service_ref, state_catalog)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/conductor/api.py", line 180, in service_update
  TRACE nova.servicegroup.drivers.db     return self._manager.service_update(context, service, values)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/utils.py", line 949, in wrapper
  TRACE nova.servicegroup.drivers.db     return func(*args, **kwargs)
  TRACE nova.servicegroup.drivers.db   File "/usr/local/lib/python2.7/dist-packages/oslo/messaging/rpc/server.py", line 139, in inner
  TRACE nova.servicegroup.drivers.db     return func(*args, **kwargs)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/conductor/manager.py", line 320, in service_update
  TRACE nova.servicegroup.drivers.db     svc = self.db.service_update(context, service['id'], values)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/db/api.py", line 150, in service_update
  TRACE nova.servicegroup.drivers.db     return IMPL.service_update(context, service_id, values)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 125, in wrapper
  TRACE nova.servicegroup.drivers.db     return f(*args, **kwargs)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 181, in wrapped
  TRACE nova.servicegroup.drivers.db     return f(*args, **kwargs)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 524, in service_update
  TRACE nova.servicegroup.drivers.db     with_compute_node=False, session=session)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 424, in _service_get
  TRACE nova.servicegroup.drivers.db     result = query.first()
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2341, in first
  TRACE nova.servicegroup.drivers.db     ret = list(self[0:1])
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2208, in __getitem__
  TRACE nova.servicegroup.drivers.db     return list(res)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2412, in __iter__
  TRACE nova.servicegroup.drivers.db     return self._execute_and_instances(context)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2425, in _execute_and_instances
  TRACE nova.servicegroup.drivers.db     close_with_result=True)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2416, in _connection_from_session
  TRACE nova.servicegroup.drivers.db     **kw)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 854, in connection
  TRACE nova.servicegroup.drivers.db     close_with_result=close_with_result)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 858, in _connection_for_bind
  TRACE nova.servicegroup.drivers.db     return self.transaction._connection_for_bind(engine)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 329, in _connection_for_bind
  TRACE nova.servicegroup.drivers.db     transaction = conn.begin()
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 420, in begin
  TRACE nova.servicegroup.drivers.db     self.__transaction = RootTransaction(self)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1357, in __init__
  TRACE nova.servicegroup.drivers.db     self.connection._begin_impl(self)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 490, in _begin_impl
  TRACE nova.servicegroup.drivers.db     self.dispatch.begin(self)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/event/attr.py", line 260, in __call__
  TRACE nova.servicegroup.drivers.db     fn(*args, **kw)
  TRACE nova.servicegroup.drivers.db   File "/usr/local/lib/python2.7/dist-packages/oslo/db/sqlalchemy/session.py", line 331, in _begin_ping_listener
  TRACE nova.servicegroup.drivers.db     connection.scalar(select([1]))
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 659, in scalar
  TRACE nova.servicegroup.drivers.db     return self.execute(object, *multiparams, **params).scalar()
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 729, in execute
  TRACE nova.servicegroup.drivers.db     return meth(self, multiparams, params)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/sql/elements.py", line 321, in _execute_on_connection
  TRACE nova.servicegroup.drivers.db     return connection._execute_clauseelement(self, multiparams, params)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 826, in _execute_clauseelement
  TRACE nova.servicegroup.drivers.db     compiled_sql, distilled_params
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 893, in _execute_context
  TRACE nova.servicegroup.drivers.db     None, None)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1169, in _handle_dbapi_exception
  TRACE nova.servicegroup.drivers.db     dbapi_conn_wrapper = self.connection
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 236, in connection
  TRACE nova.servicegroup.drivers.db     return self._revalidate_connection()
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 244, in _revalidate_connection
  TRACE nova.servicegroup.drivers.db     self.__connection = self.engine.raw_connection()
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1848, in raw_connection
  TRACE nova.servicegroup.drivers.db     return self.pool.unique_connection()
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 280, in unique_connection
  TRACE nova.servicegroup.drivers.db     return _ConnectionFairy._checkout(self)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 641, in _checkout
  TRACE nova.servicegroup.drivers.db     fairy = _ConnectionRecord.checkout(pool)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 442, in checkout
  TRACE nova.servicegroup.drivers.db     dbapi_connection = rec.get_connection()
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 505, in get_connection
  TRACE nova.servicegroup.drivers.db     self.connection = self.__connect()
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 537, in __connect
  TRACE nova.servicegroup.drivers.db     connection = self.__pool._creator()
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/strategies.py", line 96, in connect
  TRACE nova.servicegroup.drivers.db     connection_invalidated=invalidated
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/util/compat.py", line 199, in raise_from_cause
  TRACE nova.servicegroup.drivers.db     reraise(type(exception), exception, tb=exc_tb)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/strategies.py", line 90, in connect
  TRACE nova.servicegroup.drivers.db     return dialect.connect(*cargs, **cparams)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/default.py", line 377, in connect
  TRACE nova.servicegroup.drivers.db     return self.dbapi.connect(*cargs, **cparams)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/MySQLdb/__init__.py", line 81, in Connect
  TRACE nova.servicegroup.drivers.db     return Connection(*args, **kwargs)
  TRACE nova.servicegroup.drivers.db   File "/usr/lib/python2.7/dist-packages/MySQLdb/connections.py", line 187, in __init__
  TRACE nova.servicegroup.drivers.db     super(Connection, self).__init__(*args, **kwargs2)
  TRACE nova.servicegroup.drivers.db OperationalError: (OperationalError) (2003, "Can't connect to MySQL server on '10.128.30.11' (111)") None None
  TRACE nova.servicegroup.drivers.db

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https://bugs.launchpad.net/nova/+bug/1444532/+subscriptions
Follow ups

[Bug 1444532] Re: nova-scheduler doesnt reconnect to databases when started and database is down
From: Chuck Short, 2016-11-18
[Bug 1444532] Re: nova-scheduler doesnt reconnect to databases when started and database is down
From: Sylvain Bauza, 2015-05-05
[Bug 1444532] Re: nova-scheduler doesnt reconnect to databases when started and database is down
From: Brian Murray, 2015-04-17
[Bug 1444532] Re: nova-scheduler doesnt reconnect to databases when started and database is down
From: Alejandro Comisario, 2015-04-15
[Bug 1444532] [NEW] nova-scheduler doesnt reconnect to databases when started and database is down
From: Alejandro Comisario, 2015-04-15
References

[Bug 1444532] [NEW] nova-scheduler doesnt reconnect to databases when started and database is down
From: Alejandro Comisario, 2015-04-15