So the test against plain cx_Oracle is a datapoint sure, but since you
say that connects, we need to look at what your application is doing.
The first thing I see in the stack trace is that the application is
raising a sqlalchemy.exc.DisconnectionError. This is an exception that
SQLAlchemy itself *does not raise* - only the calling application or
library would do this, to indicate to the connection pool that it needs
to reconnect.
As I'm getting the impression this is within code you aren't familiar
with, I went to figure out what airflow is (hey airbnb using SQLAlchemy!
woop) and I can find at least one probable cause which is this code:
https://github.com/apache/incubator-airflow/blob/ff45d8f2218a8da9328161aa66d004c3db3b367e/airflow/utils/db.py#L70
and that code will not work on Oracle. You can't say "SELECT 1" on
Oracle, you need to say "SELECT 1 FROM DUAL".
They have copied the example verbatim from the 0.9 version of the docs,
which is unfortunate because that example has this bug as well as that
it is just crashing on any "except:", not just the ones that indicate a
disconnect. That was back when I was still writing example code with
the perception that people would obviously "fix up" the code to suit
their specific case (e.g. what kinds of exceptions they'd care about for
specific databases, etc).
Airflow needs to fix their example to match the modern form which is at
http://docs.sqlalchemy.org/en/latest/core/pooling.html#disconnect-handling-pessimistic.
I would submit this to them.
On 10/27/2016 03:46 AM, Vincent B. wrote:
Thanks again.
So i configured several pool_timeout ranging from 0.000001 to 30 and i
still get this *This connection is closed *
Is there a way to have more details regarding my sqlalchemy connection?
I am already using *echo=True*, *echo_pool=True* and Python's logging
|
logging.basicConfig()
logging.getLogger('sqlalchemy.engine').setLevel(logging.DEBUG)
|
I also tried to use NullPool before, without success.
On Wednesday, October 26, 2016 at 6:56:53 PM UTC+2, Mike Bayer wrote:
oh. then they are timing out your connections due to inactivity. Set
the "pool_timeout" parameter to a number of seconds less than this
timeout.
On 10/26/2016 10:24 AM, Vincent B. wrote:
> Thanks for this answer.
>
> As you suggested i tried to connect, with success, to my database
> through cx_oracle.
>
>
> |
> ip = '[MyOracleServerIP]'
> port = 1521
> service_name = '[MyServiceName]'
> dsn = cx_Oracle.makedsn(ip, port, service_name=service_name)
> db = cx_Oracle.connect('[login]', '[password]', dsn)
> print db.version
> db.close()
> |
>
> Output : 12.1.0.2.0
>
> Functional both in "test" and "run".
>
>
> Le mercredi 26 octobre 2016 15:45:59 UTC+2, Mike Bayer a écrit :
>
> This is connectivity issues, I have no idea what airflow is,
however
> if you're dropping connections this would be something to
email the
> cx_oracle list about . The error message looks like you're not
> able to establish a connection in the first place. You might
want
> to create a plain cx_oracle test script at least to make the
options
> and the error clear.
>
>
> On Oct 26, 2016 9:22 AM, "Vincent B." <[email protected]
> <javascript:>> wrote:
>
> Hi,
>
> I am using sqlalchemy 1.0.5, Airflow 1.7.1.3, Python 2.7 and
> Oracle 12.
>
> I'm pretty much stuck with the integration of a connexion to
> Oracle through sqlalchemy in an Airflow Airbnb script.
>
>
> Here is my log from Airflow/sqlalchemy.
>
> |
> [2016-10-26 14:51:07,574] {base.py:719} INFO - COMMIT
> [2016-10-26 14:51:07,631] {log.py:109} INFO - SELECT USER
FROM DUAL
> [2016-10-26 14:51:07,631] {log.py:109} INFO - {}
> [2016-10-26 14:51:07,633] {log.py:109} INFO - SELECT
CAST('test
> plain returns' AS VARCHAR(60 CHAR)) AS anon_1 FROM DUAL
> [2016-10-26 14:51:07,633] {log.py:109} INFO - {}
> [2016-10-26 14:51:07,634] {log.py:109} INFO - SELECT
CAST('test
> unicode returns' AS NVARCHAR2(60)) AS anon_1 FROM DUAL
> [2016-10-26 14:51:07,634] {log.py:109} INFO - {}
> [2016-10-26 14:51:07,638] {log.py:109} INFO - Disconnection
> detected on checkout:
> [2016-10-26 14:51:07,638] {log.py:109} INFO - Invalidate
> connection <cx_Oracle.Connection to
>
[MyDataBaseName]@(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=[MyOracleServerIP])(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=I2B2)))>
> (reason: DisconnectionError:)
> [2016-10-26 14:51:07,678] {log.py:109} INFO - Disconnection
> detected on checkout:
> [2016-10-26 14:51:07,678] {log.py:109} INFO - Invalidate
> connection <cx_Oracle.Connection to
>
[MyDataBaseName]@(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=[MyOracleServerIP])(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=I2B2)))>
> (reason: DisconnectionError:)
> [2016-10-26 14:51:07,714] {log.py:109} INFO - Reconnection
> attempts exhausted on checkout
> [2016-10-26 14:51:07,715] {log.py:109} INFO - Invalidate
> connection <cx_Oracle.Connection to
>
[MyDataBaseName]@(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=[MyOracleServerIP])(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=I2B2)))>
> [2016-10-26 14:51:07,716] {models.py:1286} ERROR - This
> connection is closed
> Traceback (most recent call last):
> File
>
"/usr/local/lib/python2.7/dist-packages/airflow/models.py", line
> 1245, in run
> result = task_copy.execute(context=context)
> File
>
"/usr/local/lib/python2.7/dist-packages/airflow/operators/python_operator.py",
> line 66, in execute
> return_value = self.python_callable(*self.op_args,
> **self.op_kwargs)
> File "/root/airflow/dags/debug_py2b2_connect.py", line
41, in
> test_connect
> connection=i2b2data.engine.connect()
> File
>
"/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py",
> line 2085, in connect
> return self._connection_cls(self, **kwargs)
> File
>
"/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py",
> line 90, in __init__
> if connection is not None else engine.raw_connection()
> File
>
"/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py",
> line 2171, in raw_connection
> self.pool.unique_connection, _connection)
> File
>
"/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py",
> line 2141, in _wrap_pool_connect
> return fn()
> File
> "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py",
> line 328, in unique_connection
> return _ConnectionFairy._checkout(self)
> File
> "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py",
> line 804, in _checkout
> raise exc.InvalidRequestError("This connection is
closed")
> InvalidRequestError: This connection is closed
> [2016-10-26 14:51:07,718] {models.py:1306} INFO - Marking
task
> as FAILED.
>
> |
>
>
> Here is my sql alchemy __init__code in my python class
> |
> def __init__(self,connection_uri,params):
> if connection_uri.startswith("oracle"):
> os.environ['NLS_LANG']= 'AMERICAN_AMERICA.AL32UTF8'
> self.engine=sqlalchemy.create_engine(connection_uri,
**params)
> Session = sessionmaker(bind=self.engine, autoflush=True,
> autocommit=False)
> self.session = Session()
> self.metadata = MetaData()
> self.metadata.bind=self.engine
> |
>
>
> This error "This connection is closed" is *not *raised
when in
> airflow "test" mode. I can connect and update my database
and my
> python script works perfectly.
> However in airflow "run" mode it fails.
>
> I also have this oracle warning,
> |
> <msg time='2016-10-17T11:52:47.755+02:00' org_id='xxxxxx'
> comp_id='rdbms' type='UNKNOWN' level='16' host_id='xxxxxxx'
> host_addr='xxxxxx' module='python@xxxxxxx' pid='8978'>
> <txt>Using deprecated SQLNET.ALLOWED_LOGON_VERSION parameter.
> </txt> </msg>
> |
>
> But it seems unrelated as i get this warning when i
execute my
> script in "test" (success) and "run" (failure) mode. We are
> planning to fix this soon.
>
>
> I have no clue if this error is related to airflow, oracle or
> sqlalchemy configuration.
>
>
>
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