[GitHub] [incubator-kvrocks] moonsphere commented on issue #1235: Inconsistent error "Can't write to slot being migrated which is in write forbidden phase"

["moonsphere (via GitHub)" <gi...@apache.org>]

moonsphere commented on issue #1235:
URL: https://github.com/apache/incubator-kvrocks/issues/1235#issuecomment-1408673739

   Hi, @git-hulk  thanks for the reply.
   
   From the log, we can see it already has `-` prefix 
   
   ```
   server 0.0.0.0:6666 handle error response: -Can't write to slot being migrated which is in write forbidden phase
   ```
   
   My question for this issue is "This error  make a different user experience when the user switches their application from redis-cluster to kvrocks-cluster".
   
   We can imagine that :
   
   1. There are two nodes: `nodeA` and `nodeB`,  `slot1` is on `nodeA`
   2. Admin execute `clusterx migrate` in kvrocks-cluster and `set slots migrating/importing + migrate` in redis-cluster
   3. User's application set a `key1` to nodeA and `key1` belong to `slot1`
   
   For redis cluster:
   
   Due to the single thread execution model, `set key1` will wait `migrate` finished, after that it will find key1 not exist in nodeA then `-ASK + ASKING` to redirect `set key1` to nodeB,  `-ASK` can be right handle by mainstream redis sdk.
   
   But for kvrocks cluster:
   
   `set key1` will meet `forbidden_slot_` mark (after it finish send snapshot) and return a error with `-Can't ...`, all redis sdk could not handle it, the error will throw to application directly.


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