geektutu/7days-golang · error · ErrShutdown

connection is shut down

Error message

connection is shut down

What it means

Sentinel error ErrShutdown (io.Closer semantics) indicating the client connection is no longer usable: either the user called Close (closing=true) or the server told the client to stop (shutdown=true). Returned by Close when already closing and used to fail pending calls.

Source

Thrown at gee-rpc/day3-service/client.go:50

// Client represents an RPC Client.
// There may be multiple outstanding Calls associated
// with a single Client, and a Client may be used by
// multiple goroutines simultaneously.
type Client struct {
	cc       codec.Codec
	opt      *Option
	sending  sync.Mutex // protect following
	header   codec.Header
	mu       sync.Mutex // protect following
	seq      uint64
	pending  map[uint64]*Call
	closing  bool // user has called Close
	shutdown bool // server has told us to stop
}

var _ io.Closer = (*Client)(nil)

var ErrShutdown = errors.New("connection is shut down")

// Close the connection
func (client *Client) Close() error {
	client.mu.Lock()
	defer client.mu.Unlock()
	if client.closing {
		return ErrShutdown
	}
	client.closing = true
	return client.cc.Close()
}

// IsAvailable return true if the client does work
func (client *Client) IsAvailable() bool {
	client.mu.Lock()
	defer client.mu.Unlock()
	return !client.shutdown && !client.closing
}

View on GitHub (pinned to cf36443821)

Solutions

1. Do not use the Client after calling Close; create a new one via Dial.
2. Check for errors.Is(err, ErrShutdown) and reconnect with a fresh client.
3. For graceful restarts, drain outstanding Call.Done channels before closing the client.

When it happens

Trigger: Thrown at gee-rpc/day3-service/client.go:50 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of geektutu/7days-golang@cf36443821 (2026-09-03). Data as JSON: /api/errors/e4ee8d4d27318956. Report an issue: GitHub.