SQLSTATE[08004] [1040] Too many connections in a batch of functional tests

[papatti]

PHPUnit tests fail after the first ~200 tests with SQLSTATE[08004] [1040] Too many connections.
Each api call will trigger a full Symfony boot sequence, including PropelBundle's boot function, which creates a new connection each time, until the limit is reached.

I assumed, that Propel's ConnectionManagerSingle should close existing connections when new configuration is provided (ConnectionManagerSingle::setConfiguration()) by detaching connection objects. If nobody uses them, objects are destroyed, connections are closed. But not...

In Propel1 there was a !\Propel::isInit() function, this was used in PropelBundle to avoid multiple connection instances, but this has been removed, and the Propel::init() is also deprecated.

I reported this problem for Propel guys, but no answer till now (propelorm/Propel2#1906).

I managed to avoid this problem by emulating Propel1's behaviour by having

    private static $isInitialized = false;

    /**
     * {@inheritdoc}
     */
    public function boot(): void
    {
        try {
            if (!self::$isInitialized) {
                $this->configureConnections();

                if ($this->container->getParameter('propel.logging')) {
                    $this->configureLogging();
                }

                self::$isInitialized = true;
            }
        } catch( \Exception $e ) {
        }
    }

in PropelBundle, but I'm not convinced that this is the correct solution.

(Symfony 5.4.18, PHP 8.0.24, MySQL 5.7, PHPUnit 9.3.11)