etcdctl watch returned before real value change

[linfan]

Hi,

I wrote below script watching path "/demo", it suppose to append a prefix "Hello" when the content in that path changed. Then I triggered a change on another node. But as a result, the "etcdctl get" command always got the old value of path "/demo", not the changed one.

while true; do 
    etcdctl watch ${KEY}
    etcdctl update ${KEY} "Hello $(etcdctl get ${KEY})"    
done

However, after I put a bit delay before getting the value of path, it begin to work as expected.

while true; do 
    etcdctl watch ${KEY}
    sleep 1s      # <-- wait 1s here
    etcdctl update ${KEY} "Hello $(etcdctl get ${KEY})"    
done

So from appearance, the reason is when "etcdctl watch" command returned, etcd is still under synchronisation process and not ready to provide the new value.

Is this a designed behaviour or unexpected issue?

[xiang90]

@linfan Can you try to reproduce this on current master? Thanks.

[linfan]

I tried again against the master build, this issue already gone. Thanks!

The etcd version tagged as 2.0.3

root@7db926a0818c:/etcd/bin# ./etcd --version
etcd version 2.0.3