memoryError when connect() with a engine created by create_engine from sqlalchemy in flask

问题

I want to access an oracle database through sqlalchemy in flask development. An engine is created by sqlalchemy create_engine() MemoryError is reported when engine.connect() is called.

If setting a wrong password in the linkword, it would report: sqlalchemy.exc.DatabaseError: (cx_Oracle.DatabaseError) ORA-01017: invalid username/password; logon denied.

With the correct password and user name, MemoryError would appear.

It is very strange when i copy the codes into jupyter or a new project (not a flask project)in pycharm, the codes work well. I wonder if it is possible the flask has problems.

from sqlalchemy import create_engine

@test_bp.route('/testtd')
def testtd():
    #the linkword has no problem because these codes works in Jupyter or a new project
    linkword = 'blablabla'


    engine = create_engine(linkword)

    #here i got a problem. memoryError was reported.
    conn = engine.connect()

    ret = conn.execute('select table_name from user_tables').fetchall()
    print(ret)
    conn.close()

---

Errors reported by pycharm are as follows:
  File "E:\Projects\Python\DAM2\blueprints\test.py", line 19, in testtd
    conn = engine.connect()
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\engine\base.py", line 2196, in connect
    return self._connection_cls(self, **kwargs)
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\engine\base.py", line 103, in __init__
    else engine.raw_connection()
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\engine\base.py", line 2296, in raw_connection
    self.pool.unique_connection, _connection
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\engine\base.py", line 2265, in _wrap_pool_connect
    return fn()
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\pool\base.py", line 303, in unique_connection
    return _ConnectionFairy._checkout(self)
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\pool\base.py", line 760, in _checkout
    fairy = _ConnectionRecord.checkout(pool)
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\pool\base.py", line 492, in checkout
    rec = pool._do_get()
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\pool\impl.py", line 139, in _do_get
    self._dec_overflow()
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\util\langhelpers.py", line 68, in __exit__
    compat.reraise(exc_type, exc_value, exc_tb)
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\util\compat.py", line 153, in reraise
    raise value
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\pool\impl.py", line 136, in _do_get
    return self._create_connection()
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\pool\base.py", line 308, in _create_connection
    return _ConnectionRecord(self)
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\pool\base.py", line 437, in __init__
    self.__connect(first_connect_check=True)
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\pool\base.py", line 649, in __connect
    ).exec_once(self.connection, self)
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\event\attr.py", line 287, in exec_once
    self(*args, **kw)
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\event\attr.py", line 297, in __call__
    fn(*args, **kw)
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\util\langhelpers.py", line 1443, in go
    return once_fn(*arg, **kw)
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\engine\strategies.py", line 199, in first_connect
    dialect.initialize(c)
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\dialects\oracle\cx_oracle.py", line 832, in initialize
    super(OracleDialect_cx_oracle, self).initialize(connection)
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\dialects\oracle\base.py", line 1140, in initialize
    super(OracleDialect, self).initialize(connection)
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\engine\default.py", line 297, in initialize
    connection
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\dialects\oracle\base.py", line 1239, in _get_default_schema_name
    connection.execute("SELECT USER FROM DUAL").scalar()
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\engine\base.py", line 982, in execute
    return self._execute_text(object_, multiparams, params)
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\engine\base.py", line 1155, in _execute_text
    parameters,
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\engine\base.py", line 1248, in _execute_context
    e, statement, parameters, cursor, context
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\engine\base.py", line 1468, in _handle_dbapi_exception
    util.reraise(*exc_info)
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\util\compat.py", line 153, in reraise
    raise value
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\engine\base.py", line 1244, in _execute_context
    cursor, statement, parameters, context
  File "C:\Users\GAC\.virtualenvs\DAM2-SwV_IMXP\lib\site-packages\sqlalchemy\engine\default.py", line 552, in do_execute
    cursor.execute(statement, parameters)
MemoryError

how can i fix the codes?

来源：https://stackoverflow.com/questions/57160396/memoryerror-when-connect-with-a-engine-created-by-create-engine-from-sqlalchem