client.go
func OptClientTotalPoolSize(size int) ClientOption {
	return func(options *ClientOptions) error {
		options.TotalPoolSize = size
		return nil
	}
}
func OptClientTotalPoolSize(size int) ClientOption {
	return func(options *ClientOptions) error {
		options.TotalPoolSize = size
		return nil
	}
}
// OptClientTotalPoolSize is the maximum number of connections in the pool.