[#CONPY-255] ConnectionPool.get_connection does not raise mariadb.PoolError

[CONPY-255] ConnectionPool.get_connection does not raise mariadb.PoolError Created: 2023-03-28 Updated: 2023-04-11 Resolved: 2023-04-11
Status:	Closed
Project:	MariaDB Connector/Python
Component/s:	Connection Pooling
Affects Version/s:	1.1.5, 1.1.6
Fix Version/s:	1.1.7

Type:

Bug

Priority:

Minor

Reporter:

G.Mech

Assignee:

Georg Richter

Resolution:

Fixed

Votes:

Labels:

None

Environment:

Win10 21H2, MariaDB Server 10.6.11 (official docker image)

Attachments:

test_raises_pool_error.py

Python Version:

3.10.4

Description

Steps to reproduce

set enviroment variables to allow login to server (see attached file)
Run python example

The example code initializes a ConnectionPool with 3 connections and calls get_connection() 4 times.

Expected outcome

As the documentation says, get_connection should raise a PoolError, because no connection is available:

ConnectionPool.get_connection()
Returns a connection from the connection pool or raises a PoolError exception if a connection is not available.

Actual outcome

get_connection() does not raise PoolError but returns None

Workaround

Do not catch PoolError but test return value:

conn = pool.get_connection()

if not conn:

    # put error handling here

Remarks

There is probably much code which relies on the current implementation, so its probably better to change the documentation.

There is a test case test_connection_pool_maxconn in .\testing\test\integration\test_pooling.py but it does not assert that a PoolError is raised.

Comments

Comment by G.Mech [ 2023-03-28 ]

I can reproduce the issue by changing test_connection_pool_maxconn as follows:

    def test_connection_pool_maxconn(self):

        default_conf = conf()

        pool = mariadb.ConnectionPool(pool_name="test_max_size",

                                      **default_conf)

        connections = []

        for i in range(1, 6):

            connections.append(pool.get_connection())

        try:

            with self.assertRaises(mariadb.PoolError):

                pool.get_connection()

        finally:

            for c in connections:

                c.close()

            pool.get_connection()

            pool.close()

Comment by Georg Richter [ 2023-04-11 ]

Thanks for your bug report.
I just checked other python database drivers, they all raise an exception - so we should do the same.

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