In the client side, we use fmt.Sprintf("%08d", j) this format to represent "key", which is actually some thing like 1 0000001
But when we log things, we use "%v" and hex.EncodeToString to print key

log use "%v" format will be like 01 40 32 42 42 53 12 31
log use hex.EncodeToString will be like 31313131312
only if we use "log.Infof( "%s“, key ) it will be like 1 0000001, which is easy to understand

The inconsist format of "key" is disturbing in logging.