okey doke let's see what mysql client library you are running, here's a Python
session that locates the .so file in use and then runs the ldd command, which
can give us a clue what you are running, if pymysql has no issue then we need
to suspect client library as a possible factor.
$ python
Python 3.10.0 (default, Nov 5 2021, 17:23:47) [GCC 11.2.1 20210728 (Red Hat
11.2.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from MySQLdb import _mysql
>>> import os
>>> os.system(f"ldd {_mysql.__file__}")
linux-vdso.so.1 (0x00007ffea07ee000)
libmariadb.so.3 => /lib64/libmariadb.so.3 (0x00007f37c45fa000)
libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f37c45f5000)
libc.so.6 => /lib64/libc.so.6 (0x00007f37c43ed000)
libz.so.1 => /lib64/libz.so.1 (0x00007f37c43d3000)
libssl.so.1.1 => /lib64/libssl.so.1.1 (0x00007f37c4336000)
libcrypto.so.1.1 => /lib64/libcrypto.so.1.1 (0x00007f37c4048000)
/lib64/ld-linux-x86-64.so.2 (0x00007f37c467f000)
0
On Tue, Aug 23, 2022, at 1:12 PM, Geert Jan Talens wrote:
> It does happen on every run. I'm not entirely sure how to run it on a
> different server, I'm fairly new to databases. I'm running "mysql Ver 8.0.30
> for Linux on x86_64 (MySQL Community Server - GPL)".
> The issue does not occur when using pymysql.
> On Tuesday, 23 August 2022 at 12:05:24 UTC-4 Mike Bayer wrote:
>> __
>> also try the pymysql DBAPI if that changes things, if this is mariadb try
>> mariadb-connector also.
>>
>> On Tue, Aug 23, 2022, at 12:04 PM, Mike Bayer wrote:
>>> it happens every time the program is run? there's nothing really going
>>> on in the program here, if I take out the initializer, then the program
>>> produces lots of stack traces as expected, but even then not the "server
>>> has gone away" error.
>>>
>>> can you try running on a different MySQL /MariaDB server ? like run a
>>> clean database in a container. What server version ?
>>>
>>> On Tue, Aug 23, 2022, at 11:22 AM, Geert Jan Talens wrote:
>>>> Hello Mike,
>>>>
>>>> Thank you for your reply. The traceback of the issue is below. I'm using
>>>> sqlalchemy 1.4.40 and MySQLdb 2.1.1, the problem does not occur when using
>>>> sqlite for the database instead.
>>>>
>>>> Regards,
>>>> Geert Jan
>>>>
>>>> Traceback (most recent call last):
>>>> File
>>>> "/home/talens/anaconda3/envs/hatpi/lib/python3.9/site-packages/sqlalchemy/engine/base.py",
>>>> line 1900, in _execute_context
>>>> self.dialect.do_execute(
>>>> File
>>>> "/home/talens/anaconda3/envs/hatpi/lib/python3.9/site-packages/sqlalchemy/engine/default.py",
>>>> line 732, in do_execute
>>>> cursor.execute(statement, parameters)
>>>> File
>>>> "/home/talens/anaconda3/envs/hatpi/lib/python3.9/site-packages/MySQLdb/cursors.py",
>>>> line 206, in execute
>>>> res = self._query(query)
>>>> File
>>>> "/home/talens/anaconda3/envs/hatpi/lib/python3.9/site-packages/MySQLdb/cursors.py",
>>>> line 319, in _query
>>>> db.query(q)
>>>> File
>>>> "/home/talens/anaconda3/envs/hatpi/lib/python3.9/site-packages/MySQLdb/connections.py",
>>>> line 259, in query
>>>> _mysql.connection.query(self, query)
>>>> MySQLdb._exceptions.OperationalError: (2006, 'MySQL server has gone away')
>>>>
>>>> The above exception was the direct cause of the following exception:
>>>>
>>>> Traceback (most recent call last):
>>>> File
>>>> "/home/talens/Research/HATPI/Projects/testing/testing/database_mp.py",
>>>> line 84, in <module>
>>>> main()
>>>> File
>>>> "/home/talens/Research/HATPI/Projects/testing/testing/database_mp.py",
>>>> line 78, in main
>>>> database_action(20) # Fails if line 1 is insert_integer.
>>>> File
>>>> "/home/talens/Research/HATPI/Projects/testing/testing/database_mp.py",
>>>> line 44, in database_action
>>>> result = query_integer(integer)
>>>> File
>>>> "/home/talens/Research/HATPI/Projects/testing/testing/database_mp.py",
>>>> line 37, in query_integer
>>>> result = session.execute(statement).scalar_one_or_none()
>>>> File
>>>> "/home/talens/anaconda3/envs/hatpi/lib/python3.9/site-packages/sqlalchemy/orm/session.py",
>>>> line 1712, in execute
>>>> result = conn._execute_20(statement, params or {}, execution_options)
>>>> File
>>>> "/home/talens/anaconda3/envs/hatpi/lib/python3.9/site-packages/sqlalchemy/engine/base.py",
>>>> line 1705, in _execute_20
>>>> return meth(self, args_10style, kwargs_10style, execution_options)
>>>> File
>>>> "/home/talens/anaconda3/envs/hatpi/lib/python3.9/site-packages/sqlalchemy/sql/elements.py",
>>>> line 333, in _execute_on_connection
>>>> return connection._execute_clauseelement(
>>>> File
>>>> "/home/talens/anaconda3/envs/hatpi/lib/python3.9/site-packages/sqlalchemy/engine/base.py",
>>>> line 1572, in _execute_clauseelement
>>>> ret = self._execute_context(
>>>> File
>>>> "/home/talens/anaconda3/envs/hatpi/lib/python3.9/site-packages/sqlalchemy/engine/base.py",
>>>> line 1943, in _execute_context
>>>> self._handle_dbapi_exception(
>>>> File
>>>> "/home/talens/anaconda3/envs/hatpi/lib/python3.9/site-packages/sqlalchemy/engine/base.py",
>>>> line 2124, in _handle_dbapi_exception
>>>> util.raise_(
>>>> File
>>>> "/home/talens/anaconda3/envs/hatpi/lib/python3.9/site-packages/sqlalchemy/util/compat.py",
>>>> line 208, in raise_
>>>> raise exception
>>>> File
>>>> "/home/talens/anaconda3/envs/hatpi/lib/python3.9/site-packages/sqlalchemy/engine/base.py",
>>>> line 1900, in _execute_context
>>>> self.dialect.do_execute(
>>>> File
>>>> "/home/talens/anaconda3/envs/hatpi/lib/python3.9/site-packages/sqlalchemy/engine/default.py",
>>>> line 732, in do_execute
>>>> cursor.execute(statement, parameters)
>>>> File
>>>> "/home/talens/anaconda3/envs/hatpi/lib/python3.9/site-packages/MySQLdb/cursors.py",
>>>> line 206, in execute
>>>> res = self._query(query)
>>>> File
>>>> "/home/talens/anaconda3/envs/hatpi/lib/python3.9/site-packages/MySQLdb/cursors.py",
>>>> line 319, in _query
>>>> db.query(q)
>>>> File
>>>> "/home/talens/anaconda3/envs/hatpi/lib/python3.9/site-packages/MySQLdb/connections.py",
>>>> line 259, in query
>>>> _mysql.connection.query(self, query)
>>>> sqlalchemy.exc.OperationalError: (MySQLdb._exceptions.OperationalError)
>>>> (2006, 'MySQL server has gone away')
>>>> [SQL: SELECT mytable.id
>>>> FROM mytable
>>>> WHERE mytable.id = %s]
>>>> [parameters: (20,)]
>>>> (Background on this error at: https://sqlalche.me/e/14/e3q8)
>>>>
>>>> On Monday, 22 August 2022 at 19:19:15 UTC-4 Mike Bayer wrote:
>>>>> __
>>>>> your program runs completely (thanks), and I can't reproduce any problem.
>>>>> changed line 1 as written to:
>>>>>
>>>>> # Line 1.
>>>>> # If nothing happens on line 1, line 3 fails.
>>>>> insert_integer(0) # If I do this (insert-only) line 3 fails.
>>>>> #database_action(0) # If I do this (query, insert) line 3 works.
>>>>>
>>>>>
>>>>> and no issue. output is below. Send along a stack trace for more hints.
>>>>>
>>>>> 2022-08-22 19:16:02,322 INFO sqlalchemy.engine.Engine SELECT DATABASE()
>>>>> 2022-08-22 19:16:02,322 INFO sqlalchemy.engine.Engine [raw sql] ()
>>>>> 2022-08-22 19:16:02,322 INFO sqlalchemy.engine.Engine SELECT @@sql_mode
>>>>> 2022-08-22 19:16:02,322 INFO sqlalchemy.engine.Engine [raw sql] ()
>>>>> 2022-08-22 19:16:02,323 INFO sqlalchemy.engine.Engine SELECT
>>>>> @@lower_case_table_names
>>>>> 2022-08-22 19:16:02,323 INFO sqlalchemy.engine.Engine [raw sql] ()
>>>>> 2022-08-22 19:16:02,323 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,324 INFO sqlalchemy.engine.Engine SELECT COUNT(*)
>>>>> FROM information_schema.tables WHERE table_schema = %s AND table_name = %s
>>>>> 2022-08-22 19:16:02,324 INFO sqlalchemy.engine.Engine [generated in
>>>>> 0.00016s] ('test', 'mytable')
>>>>> 2022-08-22 19:16:02,325 INFO sqlalchemy.engine.Engine
>>>>> DROP TABLE mytable
>>>>> 2022-08-22 19:16:02,325 INFO sqlalchemy.engine.Engine [no key 0.00012s] ()
>>>>> 2022-08-22 19:16:02,330 INFO sqlalchemy.engine.Engine COMMIT
>>>>> 2022-08-22 19:16:02,330 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,331 INFO sqlalchemy.engine.Engine SELECT COUNT(*)
>>>>> FROM information_schema.tables WHERE table_schema = %s AND table_name = %s
>>>>> 2022-08-22 19:16:02,331 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.006941s ago] ('test', 'mytable')
>>>>> 2022-08-22 19:16:02,332 INFO sqlalchemy.engine.Engine
>>>>> CREATE TABLE mytable (
>>>>> id INTEGER NOT NULL,
>>>>> PRIMARY KEY (id)
>>>>> )
>>>>>
>>>>>
>>>>> 2022-08-22 19:16:02,333 INFO sqlalchemy.engine.Engine [no key 0.00140s] ()
>>>>> 2022-08-22 19:16:02,342 INFO sqlalchemy.engine.Engine COMMIT
>>>>> 2022-08-22 19:16:02,344 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,345 INFO sqlalchemy.engine.Engine INSERT INTO mytable
>>>>> (id) VALUES (%s)
>>>>> 2022-08-22 19:16:02,345 INFO sqlalchemy.engine.Engine [generated in
>>>>> 0.00021s] (0,)
>>>>> 2022-08-22 19:16:02,346 INFO sqlalchemy.engine.Engine COMMIT
>>>>> 2022-08-22 19:16:02,362 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,362 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,365 INFO sqlalchemy.engine.Engine SELECT mytable.id
>>>>> FROM mytable
>>>>> WHERE mytable.id = %s
>>>>> 2022-08-22 19:16:02,365 INFO sqlalchemy.engine.Engine SELECT mytable.id
>>>>> FROM mytable
>>>>> WHERE mytable.id = %s
>>>>> 2022-08-22 19:16:02,365 INFO sqlalchemy.engine.Engine [generated in
>>>>> 0.00024s] (1,)
>>>>> 2022-08-22 19:16:02,365 INFO sqlalchemy.engine.Engine [generated in
>>>>> 0.00024s] (3,)
>>>>> 2022-08-22 19:16:02,366 INFO sqlalchemy.engine.Engine ROLLBACK
>>>>> 2022-08-22 19:16:02,366 INFO sqlalchemy.engine.Engine ROLLBACK
>>>>> 2022-08-22 19:16:02,367 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,367 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,367 INFO sqlalchemy.engine.Engine INSERT INTO mytable
>>>>> (id) VALUES (%s)
>>>>> 2022-08-22 19:16:02,367 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.0218s ago] (3,)
>>>>> 2022-08-22 19:16:02,367 INFO sqlalchemy.engine.Engine INSERT INTO mytable
>>>>> (id) VALUES (%s)
>>>>> 2022-08-22 19:16:02,367 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.02189s ago] (1,)
>>>>> 2022-08-22 19:16:02,367 INFO sqlalchemy.engine.Engine COMMIT
>>>>> 2022-08-22 19:16:02,367 INFO sqlalchemy.engine.Engine COMMIT
>>>>> 2022-08-22 19:16:02,368 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,369 INFO sqlalchemy.engine.Engine SELECT mytable.id
>>>>> FROM mytable
>>>>> WHERE mytable.id = %s
>>>>> 2022-08-22 19:16:02,369 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.003665s ago] (4,)
>>>>> 2022-08-22 19:16:02,369 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,369 INFO sqlalchemy.engine.Engine SELECT mytable.id
>>>>> FROM mytable
>>>>> WHERE mytable.id = %s
>>>>> 2022-08-22 19:16:02,370 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.004593s ago] (2,)
>>>>> 2022-08-22 19:16:02,370 INFO sqlalchemy.engine.Engine ROLLBACK
>>>>> 2022-08-22 19:16:02,370 INFO sqlalchemy.engine.Engine ROLLBACK
>>>>> 2022-08-22 19:16:02,370 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,370 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,370 INFO sqlalchemy.engine.Engine INSERT INTO mytable
>>>>> (id) VALUES (%s)
>>>>> 2022-08-22 19:16:02,370 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.0254s ago] (4,)
>>>>> 2022-08-22 19:16:02,371 INFO sqlalchemy.engine.Engine INSERT INTO mytable
>>>>> (id) VALUES (%s)
>>>>> 2022-08-22 19:16:02,371 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.02555s ago] (2,)
>>>>> 2022-08-22 19:16:02,371 INFO sqlalchemy.engine.Engine COMMIT
>>>>> 2022-08-22 19:16:02,371 INFO sqlalchemy.engine.Engine COMMIT
>>>>> 2022-08-22 19:16:02,372 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,372 INFO sqlalchemy.engine.Engine SELECT mytable.id
>>>>> FROM mytable
>>>>> WHERE mytable.id = %s
>>>>> 2022-08-22 19:16:02,372 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.007373s ago] (5,)
>>>>> 2022-08-22 19:16:02,373 INFO sqlalchemy.engine.Engine ROLLBACK
>>>>> 2022-08-22 19:16:02,373 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,373 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,373 INFO sqlalchemy.engine.Engine SELECT mytable.id
>>>>> FROM mytable
>>>>> WHERE mytable.id = %s
>>>>> 2022-08-22 19:16:02,373 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.008211s ago] (7,)
>>>>> 2022-08-22 19:16:02,373 INFO sqlalchemy.engine.Engine INSERT INTO mytable
>>>>> (id) VALUES (%s)
>>>>> 2022-08-22 19:16:02,373 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.02819s ago] (5,)
>>>>> 2022-08-22 19:16:02,374 INFO sqlalchemy.engine.Engine ROLLBACK
>>>>> 2022-08-22 19:16:02,374 INFO sqlalchemy.engine.Engine COMMIT
>>>>> 2022-08-22 19:16:02,374 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,374 INFO sqlalchemy.engine.Engine INSERT INTO mytable
>>>>> (id) VALUES (%s)
>>>>> 2022-08-22 19:16:02,374 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.0291s ago] (7,)
>>>>> 2022-08-22 19:16:02,375 INFO sqlalchemy.engine.Engine COMMIT
>>>>> 2022-08-22 19:16:02,375 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,375 INFO sqlalchemy.engine.Engine SELECT mytable.id
>>>>> FROM mytable
>>>>> WHERE mytable.id = %s
>>>>> 2022-08-22 19:16:02,375 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.01013s ago] (6,)
>>>>> 2022-08-22 19:16:02,375 INFO sqlalchemy.engine.Engine ROLLBACK
>>>>> 2022-08-22 19:16:02,376 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,376 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,376 INFO sqlalchemy.engine.Engine INSERT INTO mytable
>>>>> (id) VALUES (%s)
>>>>> 2022-08-22 19:16:02,376 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.03086s ago] (6,)
>>>>> 2022-08-22 19:16:02,376 INFO sqlalchemy.engine.Engine SELECT mytable.id
>>>>> FROM mytable
>>>>> WHERE mytable.id = %s
>>>>> 2022-08-22 19:16:02,376 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.01102s ago] (8,)
>>>>> 2022-08-22 19:16:02,376 INFO sqlalchemy.engine.Engine COMMIT
>>>>> 2022-08-22 19:16:02,377 INFO sqlalchemy.engine.Engine ROLLBACK
>>>>> 2022-08-22 19:16:02,377 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,377 INFO sqlalchemy.engine.Engine INSERT INTO mytable
>>>>> (id) VALUES (%s)
>>>>> 2022-08-22 19:16:02,377 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.03192s ago] (8,)
>>>>> 2022-08-22 19:16:02,377 INFO sqlalchemy.engine.Engine COMMIT
>>>>> 2022-08-22 19:16:02,378 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,378 INFO sqlalchemy.engine.Engine SELECT mytable.id
>>>>> FROM mytable
>>>>> WHERE mytable.id = %s
>>>>> 2022-08-22 19:16:02,378 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.01299s ago] (9,)
>>>>> 2022-08-22 19:16:02,378 INFO sqlalchemy.engine.Engine ROLLBACK
>>>>> 2022-08-22 19:16:02,379 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,379 INFO sqlalchemy.engine.Engine INSERT INTO mytable
>>>>> (id) VALUES (%s)
>>>>> 2022-08-22 19:16:02,379 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.03381s ago] (9,)
>>>>> 2022-08-22 19:16:02,379 INFO sqlalchemy.engine.Engine COMMIT
>>>>> 2022-08-22 19:16:02,381 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,381 INFO sqlalchemy.engine.Engine SELECT mytable.id
>>>>> FROM mytable
>>>>> WHERE mytable.id = %s
>>>>> 2022-08-22 19:16:02,381 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.01605s ago] (10,)
>>>>> 2022-08-22 19:16:02,381 INFO sqlalchemy.engine.Engine ROLLBACK
>>>>> 2022-08-22 19:16:02,382 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,382 INFO sqlalchemy.engine.Engine INSERT INTO mytable
>>>>> (id) VALUES (%s)
>>>>> 2022-08-22 19:16:02,382 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.03694s ago] (10,)
>>>>> 2022-08-22 19:16:02,383 INFO sqlalchemy.engine.Engine COMMIT
>>>>> 2022-08-22 19:16:02,387 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,388 INFO sqlalchemy.engine.Engine SELECT mytable.id
>>>>> FROM mytable
>>>>> WHERE mytable.id = %s
>>>>> 2022-08-22 19:16:02,388 INFO sqlalchemy.engine.Engine [generated in
>>>>> 0.00011s] (20,)
>>>>> 2022-08-22 19:16:02,389 INFO sqlalchemy.engine.Engine ROLLBACK
>>>>> 2022-08-22 19:16:02,389 INFO sqlalchemy.engine.Engine BEGIN (implicit)
>>>>> 2022-08-22 19:16:02,389 INFO sqlalchemy.engine.Engine INSERT INTO mytable
>>>>> (id) VALUES (%s)
>>>>> 2022-08-22 19:16:02,389 INFO sqlalchemy.engine.Engine [cached since
>>>>> 0.04428s ago] (20,)
>>>>> 2022-08-22 19:16:02,390 INFO sqlalchemy.engine.Engine COMMIT
>>>>>
>>>>>
>>>>> On Mon, Aug 22, 2022, at 4:21 PM, Geert Jan Talens wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I am trying to perform some database actions after multiprocessing some
>>>>>> database manipulations but in most cases I get:
>>>>>> sqlalchemy.exc.OperationalError: (MySQLdb._exceptions.OperationalError)
>>>>>> (2006, 'MySQL server has gone away')
>>>>>>
>>>>>> The code below is a working example of the problem I'm having, where the
>>>>>> success of line 3 (in main) for some reason depends on what happens on
>>>>>> line 1.
>>>>>>
>>>>>> Any help would be appreciated!
>>>>>>
>>>>>> Regards,
>>>>>> Geert Jan
>>>>>>
>>>>>> from sqlalchemy import create_engine, select
>>>>>> from sqlalchemy import Column, Integer
>>>>>> from sqlalchemy.orm import declarative_base, sessionmaker
>>>>>>
>>>>>> import multiprocessing as mp
>>>>>> import numpy as np
>>>>>>
>>>>>> Base = declarative_base()
>>>>>> Session = sessionmaker()
>>>>>>
>>>>>>
>>>>>> class MyTable(Base):
>>>>>> """This table lists all observed frames."""
>>>>>>
>>>>>> __tablename__ = 'mytable'
>>>>>>
>>>>>> # Columns in the table.
>>>>>> id = Column(Integer, primary_key=True, autoincrement=False)
>>>>>>
>>>>>>
>>>>>> def insert_integer(integer):
>>>>>>
>>>>>> with Session() as session:
>>>>>>
>>>>>> record = MyTable(id=int(integer))
>>>>>> session.add(record)
>>>>>> session.commit()
>>>>>>
>>>>>> return
>>>>>>
>>>>>>
>>>>>> def query_integer(integer):
>>>>>>
>>>>>> with Session() as session:
>>>>>>
>>>>>> statement = select(MyTable).where(MyTable.id == int(integer))
>>>>>> result = session.execute(statement).scalar_one_or_none()
>>>>>>
>>>>>> return result
>>>>>>
>>>>>>
>>>>>> def database_action(integer):
>>>>>>
>>>>>> result = query_integer(integer)
>>>>>> if result is None:
>>>>>> insert_integer(integer)
>>>>>> else:
>>>>>> print("integer already in database.")
>>>>>>
>>>>>> return
>>>>>>
>>>>>>
>>>>>> def initializer(engine):
>>>>>> # Doesn't matter if I use on or the other.
>>>>>> engine.dispose(close=False)
>>>>>> # engine.pool = engine.pool.recreate()
>>>>>>
>>>>>>
>>>>>> def main():
>>>>>>
>>>>>> # Database setup.
>>>>>> engine =
>>>>>> create_engine("mysql+mysqldb://user:[email protected]/testdb
>>>>>> <http://user:[email protected]/testdb>")
>>>>>> Session.configure(bind=engine)
>>>>>> Base.metadata.drop_all(bind=engine)
>>>>>> Base.metadata.create_all(bind=engine)
>>>>>>
>>>>>> # Line 1.
>>>>>> # If nothing happens on line 1, line 3 fails.
>>>>>> # insert_integer(0) # If I do this (insert-only) line 3 fails.
>>>>>> database_action(0) # If I do this (query, insert) line 3 works.
>>>>>>
>>>>>> # Line 2.
>>>>>> with mp.Pool(2, initializer, (engine,)) as pool:
>>>>>> pool.map(database_action, np.arange(1, 11))
>>>>>>
>>>>>> # Line 3.
>>>>>> database_action(20) # Fails if line 1 is insert_integer.
>>>>>>
>>>>>> return
>>>>>>
>>>>>>
>>>>>> if __name__ == '__main__':
>>>>>> main()
>>>>>>
>>>>>>
>>>>>> --
>>>>>> SQLAlchemy -
>>>>>> The Python SQL Toolkit and Object Relational Mapper
>>>>>>
>>>>>> http://www.sqlalchemy.org/
>>>>>>
>>>>>> To post example code, please provide an MCVE: Minimal, Complete, and
>>>>>> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
>>>>>> description.
>>>>>> ---
>>>>>> You received this message because you are subscribed to the Google
>>>>>> Groups "sqlalchemy" group.
>>>>>> To unsubscribe from this group and stop receiving emails from it, send
>>>>>> an email to [email protected].
>>>>>> To view this discussion on the web visit
>>>>>> https://groups.google.com/d/msgid/sqlalchemy/5597b069-3725-44de-88c4-4964d95d84cen%40googlegroups.com
>>>>>>
>>>>>> <https://groups.google.com/d/msgid/sqlalchemy/5597b069-3725-44de-88c4-4964d95d84cen%40googlegroups.com?utm_medium=email&utm_source=footer>.
>>>>>
>>>>
>>>>
>>>> --
>>>> SQLAlchemy -
>>>> The Python SQL Toolkit and Object Relational Mapper
>>>>
>>>> http://www.sqlalchemy.org/
>>>>
>>>> To post example code, please provide an MCVE: Minimal, Complete, and
>>>> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
>>>> description.
>>>> ---
>>>> You received this message because you are subscribed to the Google Groups
>>>> "sqlalchemy" group.
>>>> To unsubscribe from this group and stop receiving emails from it, send an
>>>> email to [email protected].
>>>> To view this discussion on the web visit
>>>> https://groups.google.com/d/msgid/sqlalchemy/fb678c9d-4a54-4436-a86e-be81d764af8bn%40googlegroups.com
>>>>
>>>> <https://groups.google.com/d/msgid/sqlalchemy/fb678c9d-4a54-4436-a86e-be81d764af8bn%40googlegroups.com?utm_medium=email&utm_source=footer>.
>>>
>>
>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
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--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
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