Long lived connections may make some DB operation difficult.
(e.g. retiring load balanced DB server.)
So SetConnMaxLifetime closes long lived connections.
It can be used to limit maximum idle time, too.
Closing idle connections reduces active connections while application is idle
and avoids connections are closed by server side (cause errBadConn while querying).
Run-TryBot: Brad Fitzpatrick <firstname.lastname@example.org>
TryBot-Result: Gobot Gobot <email@example.com>
Reviewed-by: Brad Fitzpatrick <firstname.lastname@example.org>