def clear_stale_cached_connections!
keys = @reserved_connections.keys - Thread.list.find_all { |t|
t.alive?
}.map { |thread| thread.object_id }
keys.each do |key|
conn = @reserved_connections[key]
ActiveSupport::Deprecation.warn("Database connections will not be closed automatically, please close your\ndatabase connection at the end of the thread by calling `close` on your\nconnection. For example: ActiveRecord::Base.connection.close\n") if conn.in_use?
checkin conn
@reserved_connections.delete(key)
end
end