Fix sporadic pool timeouts with IdleTimeout != 0. Fixes redis#195.

cluster.go

@@ -146,6 +146,7 @@ func (c *ClusterClient) process(cmd Cmder) {
 			pipe.Process(NewCmd("ASKING"))
 			pipe.Process(cmd)
 			_, _ = pipe.Exec()
+			pipe.Close()
 			ask = false
 		} else {
 			client.Process(cmd)

pool.go

@@ -163,8 +163,12 @@ func (p *connPool) First() *conn {
 		select {
 		case cn := <-p.freeConns:
 			if p.isIdle(cn) {
-				p.conns.Remove(cn)
-				continue
+				var err error
+				cn, err = p.replace(cn)
+				if err != nil {
+					log.Printf("redis: replace failed: %s", err)
+					continue
+				}
 			}
 			return cn
 		default:
@@ -181,8 +185,12 @@ func (p *connPool) wait() *conn {
 		select {
 		case cn := <-p.freeConns:
 			if p.isIdle(cn) {
-				p.Remove(cn)
-				continue
+				var err error
+				cn, err = p.replace(cn)
+				if err != nil {
+					log.Printf("redis: replace failed: %s", err)
+					continue
+				}
 			}
 			return cn
 		case <-deadline:
@@ -257,16 +265,24 @@ func (p *connPool) Put(cn *conn) error {
 	return nil
 }
 
+func (p *connPool) replace(cn *conn) (*conn, error) {
+	newcn, err := p.new()
+	if err != nil {
+		_ = p.conns.Remove(cn)
+		return nil, err
+	}
+	_ = p.conns.Replace(cn, newcn)
+	return newcn, nil
+}
+
 func (p *connPool) Remove(cn *conn) error {
 	// Replace existing connection with new one and unblock waiter.
-	newcn, err := p.new()
+	newcn, err := p.replace(cn)
 	if err != nil {
-		log.Printf("redis: new failed: %s", err)
-		return p.conns.Remove(cn)
+		return err
 	}
-	err = p.conns.Replace(cn, newcn)
 	p.freeConns <- newcn
-	return err
+	return nil
 }
 
 // Len returns total number of connections.