Godeps/_workspace/src/gopkg.in/mgo.v2/session.go
func (s *Session) SetPoolLimit(limit int) {
	s.m.Lock()
	s.poolLimit = limit
	s.m.Unlock()
}
func (s *Session) SetPoolLimit(limit int) {
	s.m.Lock()
	s.poolLimit = limit
	s.m.Unlock()
}
// SetPoolLimit sets the maximum number of sockets in use in a single server
// before this session will block waiting for a socket to be available.
// The default limit is 4096.
//
// This limit must be set to cover more than any expected workload of the
// application. It is a bad practice and an unsupported use case to use the
// database driver to define the concurrency limit of an application. Prevent
// such concurrency "at the door" instead, by properly restricting the amount
// of used resources and number of goroutines before they are created.