config_test.yml

doctrine:
    dbal:
        driver: pdo_sqlite
        path: %kernel.cache_dir%/data.db

parameters:
    doctrine.dbal.connection_factory.class: Acme\Bundle\PerProcessConnectionFactory

PerProcessConnectionFactory.php

<?php

namespace Acme\Bundle;
 
use Doctrine\Bundle\DoctrineBundle\ConnectionFactory;
use Doctrine\Common\EventManager;
use Doctrine\DBAL\Configuration;

class PerProcessConnectionFactory extends ConnectionFactory
{
    function createConnection(array $params, Configuration $config = null, EventManager $eventManager = null, array $mappingTypes = array())
    {
        $params['path'] = $params['path'] . '-' . getmypid();
        return parent::createConnection($params, $config, $eventManager, $mappingTypes);
    }
}