У меня такой вопрос, если в коннекшн стринге ошибка то

r2d2 просто в бесконечный цикл уходит:
2020-05-13T16:30:07.777244900+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:07.778244700+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:07.778244700+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:07.778244700+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:07.778244700+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:07.778244700+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:07.778244700+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:07.778244700+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:07.778244700+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:07.778244700+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:08.179240800+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:08.179240800+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:08.179240800+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:08.179240800+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:08.179240800+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:08.179240800+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:08.179240800+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:08.179240800+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

2020-05-13T16:30:08.179240800+03:00 ERROR r2d2 - missing "=" after "postgre://bac" in connection info string

С этим можно что-то сделать?

Да можно. r2d2 -> fork -> commit -> pull request

так падажи, там рантайм сверху висит?

сообщит об ошибке наверное все таки

А еще r2d2 таймауты правильно не делает… Например, is_valid проверка будет висеть бесконечно (ну, не бесконечно, а очень долго, 10 минут, например), если tcp соединение вдруг отвалится без TCP RST.