This session is in 'prepared' state; no further SQL can be emitted within this transaction.

[Foorack]

If a scheduled cron task is running at the exact same time a salto request comes in then the Database throws an error due to multi-thread access. Create one Session per thread instead, see: https://stackoverflow.com/questions/39126810/this-session-is-in-prepared-state-no-further-error-with-sqlalchemy-using-sc

2021-03-20 15:00:02,704 ERROR Exception on /salto/mek [GET]
Traceback (most recent call last):
  File "/usr/local/lib/python3.9/dist-packages/flask/app.py", line 2447, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/local/lib/python3.9/dist-packages/flask/app.py", line 1952, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/local/lib/python3.9/dist-packages/flask/app.py", line 1821, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/local/lib/python3.9/dist-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/usr/local/lib/python3.9/dist-packages/flask/app.py", line 1950, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/local/lib/python3.9/dist-packages/flask/app.py", line 1936, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/srv/koseki/koseki/plugins/salto/salto.py", line 58, in salto_mek
    self.storage.session.query(Person).filter_by(state="active").all()
  File "/usr/local/lib/python3.9/dist-packages/sqlalchemy/orm/query.py", line 3373, in all
    return list(self)
  File "/usr/local/lib/python3.9/dist-packages/sqlalchemy/orm/query.py", line 3535, in __iter__
    return self._execute_and_instances(context)
  File "/usr/local/lib/python3.9/dist-packages/sqlalchemy/orm/query.py", line 3556, in _execute_and_instances
    conn = self._get_bind_args(
  File "/usr/local/lib/python3.9/dist-packages/sqlalchemy/orm/query.py", line 3571, in _get_bind_args
    return fn(
  File "/usr/local/lib/python3.9/dist-packages/sqlalchemy/orm/query.py", line 3550, in _connection_from_session
    conn = self.session.connection(**kw)
  File "/usr/local/lib/python3.9/dist-packages/sqlalchemy/orm/session.py", line 1142, in connection
    return self._connection_for_bind(
  File "/usr/local/lib/python3.9/dist-packages/sqlalchemy/orm/session.py", line 1150, in _connection_for_bind
    return self.transaction._connection_for_bind(
  File "/usr/local/lib/python3.9/dist-packages/sqlalchemy/orm/session.py", line 409, in _connection_for_bind
    self._assert_active()
  File "/usr/local/lib/python3.9/dist-packages/sqlalchemy/orm/session.py", line 282, in _assert_active
    raise sa_exc.InvalidRequestError(
sqlalchemy.exc.InvalidRequestError: This session is in 'prepared' state; no further SQL can be emitted within this transaction.
2021-03-20 15:00:05,877 INFO Job "MetricPlugin.calc_metric (trigger: cron[minute='0', second='0'], next run at: 2021-03-20 16:00:00 CET)" executed successfully```