Cluster client logs info for command not found

[kollektiv]

Version: 4a3dbb3

Using the cluster client, the internal logger is logging a lot of lines on commands. I believe cmdsInfo is being ran before cluster state has synced, which results in cmdsInfoCache storing an empty result.

When this happens, a random node is always chosen on the first attempt, which has a high chance of getting a MOVED response

Output

redis: 2019/06/26 10:14:07 cluster.go:1534: info for cmd=get not found
redis: 2019/06/26 10:14:07 cluster.go:1534: info for cmd=get not found
redis: 2019/06/26 10:14:07 cluster.go:1534: info for cmd=get not found
redis: 2019/06/26 10:14:07 cluster.go:1534: info for cmd=get not found

Example

package main

import (
	"fmt"

	"github.com/go-redis/redis"
)

func main() {
	client := redis.NewClusterClient(&redis.ClusterOptions{
		Addrs: []string{"localhost:30001"},
	})

	for i := 0; i < 1000; i++ {
		cmd := client.Get("0")
		_, err := cmd.Result()
		if err != nil && err != redis.Nil {
			fmt.Printf("error getting result: %v\n", err)
		}
	}
}

[huija]

github.com/go-redis/redis/tree/v6.15.2
我换成上面的版本没问题了, 应该是有了改动, 文档还是旧的

[vmihailenco]

I guess that is possible if you say so. But why does it happen?

[lkramer]

Hey, I'm seeing this as well. Any idea what the reason is?

[kollektiv]

@vmihailenco This has started happening since #1056. Before #1056, process would always retrieve the cluster state before through cmdSlotAndNode that called c.state.Get().

Now process is first calling cmdInfo, which calls c.cmdsInfoCache.Get() before cluster state is retrieved

[vmihailenco]

Okay, but we do we need a cluster state to retrieve commands info? ClusterClient is created with at least 1 healthy node which should be enough to retrieve commands info...

[kollektiv]

@vmihailenco Cluster state isn't necessary. Refreshing cluster state lazily creates the nodes (c.nodes.GetOrCreate).

cmdsInfo calls c.nodes.Get, so it relies on the nodes being created. What if cmdsInfo calls c.nodes.GetOrCreate instead?

[kollektiv]

Is it possible to compute the slot of the command without depending on COMMAND?

[vmihailenco]

What if cmdsInfo calls c.nodes.GetOrCreate instead?

Good call - I've sent a fix.