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Closing a connection tries to close already closed cursors #497
Description
When closing a connection the library will call .close() on every cursor created for that connection, including closed ones. While the code works, it produces a lot of logs of error level, polluting the logs.
Environment details
- OS type and version: Mac OS 10.15.7
- Python version: Python 3.8.2
- pip version: pip 20.3.3
google-cloud-bigqueryversion: 2.7.0
Steps to reproduce
- Close a cursor
- Close the connection
- Error log shows
Exception closing connection <google.cloud.bigquery.dbapi.connection.Connection object at 0x...>
Code example
from contextlib import closing
# using pybigquery
with closing(engine.raw_connection()) as conn:
with closing(conn.cursor()) as cursor:
cursor.execute(sql)Stack trace
Traceback (most recent call last):
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/base.py", line 270, in _close_connection
self._dialect.do_close(connection)
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/default.py", line 549, in do_close
dbapi_connection.close()
File "/usr/local/lib/python3.7/site-packages/google/cloud/bigquery/dbapi/_helpers.py", line 258, in with_closed_check
return method(self, *args, **kwargs)
File "/usr/local/lib/python3.7/site-packages/google/cloud/bigquery/dbapi/connection.py", line 79, in close
cursor_.close()
File "/usr/local/lib/python3.7/site-packages/google/cloud/bigquery/dbapi/_helpers.py", line 257, in with_closed_check
raise exc_class(exc_msg)
google.cloud.bigquery.dbapi.exceptions.ProgrammingError: Operating on a closed cursor.
Suggested fix
# google/cloud/bigquery/dbapi/connection.py
class Connection(object):
...
def close(self):
...
for cursor_ in self._cursors_created:
if not cursor_._closed:
cursor_.close()
Activity
[-]Closing a connection tries to close closed cursors[/-][+]Closing a connection tries to close already closed cursors[/+]plamut commentedon Jan 29, 2021
@betodealmeida Thanks for the report.
I can see where the issue is - the
raise_on_closed()decorator makes all public methods throw if an instance is "closed", which includes theCursor.close()method. Additionally, when closing a connection, the latter also attempts to automatically close all cursors that it created, thus it's not necessary to nest theclosing()context managers:However, there might be valid reasons to close a cursor early, and I agree that closing the connection at some later point should behave more gracefully, I'll fix that.
Edit: Ah, you already submitted a PR, even better, thanks!