Looks like this has a good chance of fixing the issue related to #85

channel.go

@@ -87,10 +87,17 @@ func newChannel(c *Connection, id uint16) *Channel {
 	}
 }
 
+// Signal that from now on, Channel.send() should call Channel.sendClosed()
+func (ch *Channel) setClosed() {
+	atomic.StoreInt32(&ch.closed, 1)
+}
+
 // shutdown is called by Connection after the channel has been removed from the
 // connection registry.
 func (ch *Channel) shutdown(e *Error) {
 	ch.destructor.Do(func() {
+		ch.setClosed()
+
 		ch.m.Lock()
 		defer ch.m.Unlock()
 
@@ -105,10 +112,6 @@ func (ch *Channel) shutdown(e *Error) {
 			}
 		}
 
-		// Signal that from now on, Channel.send() should call
-		// Channel.sendClosed()
-		atomic.StoreInt32(&ch.closed, 1)
-
 		// Notify RPC if we're selecting
 		if e != nil {
 			ch.errors <- e
@@ -154,7 +157,7 @@ func (ch *Channel) shutdown(e *Error) {
 // only 'channel.close' is sent to the server.
 func (ch *Channel) send(msg message) (err error) {
 	// If the channel is closed, use Channel.sendClosed()
-	if atomic.LoadInt32(&ch.closed) == 1 {
+	if ch.IsClosed() {
 		return ch.sendClosed(msg)
 	}
 
@@ -231,7 +234,7 @@ func (ch *Channel) sendOpen(msg message) (err error) {
 		}
 
 		// If the channel is closed, use Channel.sendClosed()
-		if atomic.LoadInt32(&ch.closed) == 1 {
+		if ch.IsClosed() {
 			return ch.sendClosed(msg)
 		}
 
@@ -266,7 +269,7 @@ func (ch *Channel) sendOpen(msg message) (err error) {
 		}
 	} else {
 		// If the channel is closed, use Channel.sendClosed()
-		if atomic.LoadInt32(&ch.closed) == 1 {
+		if ch.IsClosed() {
 			return ch.sendClosed(msg)
 		}
 
@@ -284,6 +287,10 @@ func (ch *Channel) sendOpen(msg message) (err error) {
 func (ch *Channel) dispatch(msg message) {
 	switch m := msg.(type) {
 	case *channelClose:
+		// Immediately indicate that this channel is closed to prevent
+		// invalid frames from being sent to the server
+		ch.setClosed()
+
 		// lock before sending connection.close-ok
 		// to avoid unexpected interleaving with basic.publish frames if
 		// publishing is happening concurrently

integration_test.go

@@ -1567,8 +1567,6 @@ func TestRepeatedChannelExceptionWithPublishAndMaxProcsIssue46(t *testing.T) {
 				if j == 0 {
 					t.Fatal("channel should not be closed")
 				}
-				// TODO remove this debug log
-				t.Logf("channel is closed, i: %d j: %d", i, j)
 				break
 			}
 			publishError := ch.Publish("not-existing-exchange", "some-key", false, false, Publishing{Body: []byte("some-data")})