ResourceClosedError on Postgres Database - support needed

[Mirek Morek]

Hello,

I use sqlalchemy to execute my tests on Postgres Database. I run like ~200 tests, every test uses its own setup and teardown. creates a connection and closes it after all.

I sometimes get ResourceClosedError ("StatementError: (sqlalchemy.exc.ResourceClosedError) This Connection is closed" in random places when tests are running one after another. It was not present on Sybase database. It seems like it wants to work on a closed connection...?

For a single test run I never got that.

Do you have any idea, what I could improve? This is a part of my code:

from sqlalchemy import create_engine
from sqlalchemy.orm import create_session
from configuration import PostgresConfiguration as PGS

class PostgresDatabase:
    def __init__(self):
        self.connection_string = r'postgresql://{}:{}@{}:{}/{}'.format(
            PGS.DB_USER,
            PGS.DB_PASSWORD,
            PGS.DB_HOST.split(":")[0],
            PGS.DB_HOST.split(":")[1],
            PGS.DB_NAME)
        self.engine = create_engine(self.connection_string, echo=True, label_length=30)
        self.session = create_session(self.engine)
        self.database_name = PGS.DB_NAME

    def get_session(self):
        """
        Retrieves current session.
        :return: current session.
        """
        return self.session

    def close_session(self):
        """
        Closes all open sessions.
        """
        self.session.close_all()

    def execute_query(self, query, commit=True):
        """
        Executes query passes as a parameter.
        :param query: passed query to be executed.
        :param commit: if True session will be committed
        :return query execution results
        """
        if commit:
            self.session.begin()
            results = self.session.execute(query)
            self.session.commit()
        else:
            results = self.session.execute(query)
        return results

[Mike Bayer]

there's no way to tell from here, information like the stack trace, and how the tests are being run (like what test runner, any multiprocessing in use, etc.) would be places to start.

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[Mirek Morek]

Ok, I see that. Could you give me some hint how could I provide the useful stack trace? What tool should I use?

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[Mike Bayer]

whatever tool you are using is telling you there is a ResourceClosedError.  That error message should be accompanied by a stack trace.    if you're running unit tests in Python, as opposed to  you're on some remote system and looking in log files, these should be very obvious as every unit test runner is going to be dumping out stack traces.

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