that "mysqldb" URL is not mysql-connector - it's MySQL-Python (old and
unmaintained) or mysqlclient (much better, if you have it installed
and not conflicting w/ MySQL-Python). You'd need to specify
"mysql+mysqlconnector://" to use that DBAPI, but also I'd recommend
trying "mysql+pymysql://" to see if you get better results.
as far as "can't connect to server" you should make sure you are not
surpassing your max_connections limit, though it should be emitting
different error message for that.
The Queue.Empty error is not the "error", it has to do with how the
QueuePool works internally to test that the pool is empty, and Python
3 can't help but report every exception in the chain. The error is
the can't connect to server.
On Fri, Jul 14, 2017 at 5:41 PM, josip povreslo
<josip.povre...@gmail.com> wrote:
> In addition to the previous email, what I do is the following:
>
> When request comes in:
> self.mysql_engine =
> create_engine('mysql+mysqldb://{}:{}@{}/{}'.format(self.db_params['dbuser'],
> self.db_params['dbpass'], self.db_params['db_hosts'][db_host_index],
> self.db_params['dbname']), pool_recycle=3600,
> connect_args={'connect_timeout': 2})
>
> And then when need to interact with the dB:
>
> connection = self.mysql_engine.connect()
> connection.execute("raw query")
> connection.close()
>
>
> Best Regards,
> Josip
>
> On Friday, July 14, 2017 at 11:36:26 PM UTC+2, josip povreslo wrote:
>>
>> Hello,
>>
>> As mentioned in the subject, we have the following packages installed:
>>
>> Python 3.5
>> mysql-connector==2.1.6
>> SQLAlchemy==1.1.11
>>
>> Our service is working until we get a bit more traffic (40 - 50 req/min),
>> although I'm still not 100% if it's a pattern, however, then we get this
>> error:
>>
>> Traceback (most recent call last):
>> File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line
>> 1122, in _do_get
>> return self._pool.get(wait, self._timeout)
>> File
>> "/usr/local/lib64/python3.5/site-packages/sqlalchemy/util/queue.py", line
>> 145, in get
>> raise Empty
>> sqlalchemy.util.queue.Empty
>> During handling of the above exception, another exception occurred:
>> Traceback (most recent call last):
>> File
>> "/usr/local/lib64/python3.5/site-packages/sqlalchemy/engine/base.py", line
>> 2147, in _wrap_pool_connect
>> return fn()
>> File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line
>> 328, in unique_connection
>> return _ConnectionFairy._checkout(self)
>> File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line
>> 766, in _checkout
>> fairy = _ConnectionRecord.checkout(pool)
>> File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line
>> 516, in checkout
>> rec = pool._do_get()
>> File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line
>> 1138, in _do_get
>> self._dec_overflow()
>> File
>> "/usr/local/lib64/python3.5/site-packages/sqlalchemy/util/langhelpers.py",
>> line 66, in __exit__
>> compat.reraise(exc_type, exc_value, exc_tb)
>> File
>> "/usr/local/lib64/python3.5/site-packages/sqlalchemy/util/compat.py", line
>> 187, in reraise
>> raise value
>> File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line
>> 1135, in _do_get
>> return self._create_connection()
>> File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line
>> 333, in _create_connection
>> return _ConnectionRecord(self)
>> File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line
>> 461, in __init__
>> self.__connect(first_connect_check=True)
>> File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line
>> 651, in __connect
>> connection = pool._invoke_creator(self)
>> File
>> "/usr/local/lib64/python3.5/site-packages/sqlalchemy/engine/strategies.py",
>> line 105, in connect
>> return dialect.connect(*cargs, **cparams)
>> File
>> "/usr/local/lib64/python3.5/site-packages/sqlalchemy/engine/default.py",
>> line 393, in connect
>> return self.dbapi.connect(*cargs, **cparams)
>> File "/usr/local/lib64/python3.5/site-packages/MySQLdb/__init__.py",
>> line 81, in Connect
>> return Connection(*args, **kwargs)
>> File "/usr/local/lib64/python3.5/site-packages/MySQLdb/connections.py",
>> line 191, in __init__
>> super(Connection, self).__init__(*args, **kwargs2)
>> _mysql_exceptions.OperationalError: (2003, "Can't connect to MySQL server
>> on 'dbhost_obviously' (4)")
>>
>> We haven't been seeing this error up until recently when we ported our
>> service to Python 3.5. I've read most of the articles related to this queue
>> empty error and most of those are from '12 or '13 and mentioning immature
>> mysql drivers. Is this still the case, should we search for an alternative
>> to mysql-connector or alternative to something else? Any help or guidance is
>> appreciated!
>>
>> Thanks!
>>
>> Best,
>> Josip
>
> --
> 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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The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
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