I use doctrine 2 PDO with mysql.
When stress testing the server, mysql reports a lot of aborted connections (up-to 20%).
I am trying to locate the issue.
I have found this tweak:
https://sroze.io/phpunit-mysql-too-many-connections-error-ab52cd5798c5
Setting processIsolation="true" option in PhpUnit XML options file seems to do the trick.
processIsolation="true"