go build
./mqtest -mq mqtt

  -broker string
        broker addr (default "127.0.0.1:1883")
  -itime int
        pub sleep time(ms) (default 300)
  -log string
        path/to/roll.log
  -mq string
        nats/nsq/kafka/rabbitmq/redis/mqtt (default "mqtt")
  -pprof string
        address:port (default ":0")
  -pub int
        pub num (default 1)
  -randtopic
        rand pub/sub a topic
  -sub int
        sub num (default 1)
  -topic int
        topic num (only randtopic=true) (default 1)