The slot is UNWRITEABLE when migrate slot

[yuelng]

When migrate slot，the cluster return ‘ASK’ err，but I found the client not process this situation correctly， help wanted， thanks @mna

[yuelng]

    // forceDial doesn't require locking (immutable)
        conn, addr, err := cluster.getConnForSlot(re.NewSlot, rc.c.forceDial, readOnly)
        if err != nil {
            // could not get connection to that node, return that error
            return nil, err
        }

https://github.com/mna/redisc/blob/master/retry_conn.go#L86 should replace by?

conn, err := cluster.getConnForAddr(re.Addr, rc.c.forceDial)

[mna]

Please clarify the issue, at a minimum it should clearly state (with minimal code to reproduce):

• What you did (call method X with struct Y)
• What happened (describe the exact error, any relevant output, etc.)
• What you expected to happen

From what I understand of your issue, you should make sure you're using a RetryConn if you want to automatically follow the ASK responses, see https://godoc.org/github.com/mna/redisc#hdr-Redirections.

[yuelng]

thanks your response，absolutely，I am using a RetryConn，I found When migrate slot，the cluster return ‘ASK’ err，the client should take the redirection addr returned by err response，but from the client logic

conn, addr, err := cluster.getConnForSlot(re.NewSlot, rc.c.forceDial, readOnly)
if err != nil {
    // could not get connection to that node, return that error
    return nil, err
}

you still take the address from the cache mapping，this is work for MOVED err response, but the retry logic take the wrong address repeatedly，So I suggest that you replace the above code，with this

conn, err := cluster.getConnForAddr(re.Addr, rc.c.forceDial)

for example：the slot 8903 is mapping the node 10.1.171.237:7008, when migrate slot 8903 to node 10.1.171.238，we have operate on this slot， then the client will got err (error) ASK 8903 10.1.171.238:7008, so the client should connect the node 10.1.171.238，not 10.1.171.237。but from the source code，you still use the mapping relation slot-address 8903 - 10.1.171.237。

[mna]

Thanks for the clarification - that makes sense, I'll try to find some time to look into that.