commands: reduce memory allocations in ZAdd.

commands.go

@@ -858,9 +858,12 @@ type ZStore struct {
 }
 
 func (c *commandable) ZAdd(key string, members ...Z) *IntCmd {
-	args := []string{"ZADD", key}
+	args := make([]string, 2+2*len(members))
-	for _, m := range members {
+	args[0] = "ZADD"
-		args = append(args, formatFloat(m.Score), m.Member)
+	args[1] = key
+	for i, m := range members {
+		args[2+2*i] = formatFloat(m.Score)
+		args[2+2*i+1] = m.Member
 	}
 	cmd := NewIntCmd(args...)
 	c.Process(cmd)

redis_test.go

@@ -267,3 +267,20 @@ func BenchmarkPipeline(b *testing.B) {
 		}
 	})
 }
+
+func BenchmarkZAdd(b *testing.B) {
+	client := redis.NewClient(&redis.Options{
+		Addr: redisAddr,
+	})
+	defer client.Close()
+
+	b.ResetTimer()
+
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			if err := client.ZAdd("key", redis.Z{float64(1), "hello"}).Err(); err != nil {
+				b.Fatal(err)
+			}
+		}
+	})
+}