Hi guys:

I find a very strange scenario today, I'm not sure how it happen, I just
found it like this. Maybe you can give me some information about it, my
Zookeeper Server is version 3.2.1.

My Zookeeper cluster contains three servers, with ip:
10.81.12.144,10.81.12.145,10.81.12.141. I wrote a client to create ephemeral
node under znode: *se/diserver_tc*. The client runs on the server with ip
10.81.13.173. The client can create a ephemeral node on zookeeper server and
write the host ip (10.81.13.173) in to the node as its data. There is only
one client process can be running at a time, because the client will listen
to a certain port.

It is strange that I found there were two ephemeral node with the ip
10.81.13.173 under znode se/diserver_tc.
*se/diserver_tc/diserver_tc0000000067*
STAT:
        czxid: 124554079820
        mzxid: 124554079820
        ctime: 1260609598547
        mtime: 1260609598547
        version: 0
        cversion: 0
        aversion: 0
        ephemeralOwner: 226627854640480810
        dataLength: 92
        numChildren: 0
        pzxid: 124554079820

*se/diserver_tc/diserver_tc0000000095
*STAT:
        czxid: 128849019107
        mzxid: 128849019107
        ctime: 1260772197356
        mtime: 1260772197356
        version: 0
        cversion: 0
        aversion: 0
        ephemeralOwner: 154673159808876591
        dataLength: 92
        numChildren: 0
        pzxid: 128849019107*
*
There are TWO with different session id! And after I kill the client process
on the server 10.81.13.173, the *se/diserver_tc/diserver_tc0000000095 *node
disappear, but the *se/diserver_tc/diserver_tc0000000067 *stay the same.
That means it is not my coding mistake to create the node twice. I checked
several times and I'm sure that there is no another client instance running.
And I use the 'stat' command to check the three zookeeper servers, and there
is no client from 10.81.13.173,

$echo stat | nc 10.81.12.144 2181
Zookeeper version: 3.2.1-808558, built on 08/27/2009 18:48 GMT
Clients:
 /10.81.13.173:35676[1](queued=0,recved=0,sent=0) *# it is caused by the nc
process*

Latency min/avg/max: 0/3/254
Received: 11081
Sent: 0
Outstanding: 0
Zxid: 0x1e000001f5
Mode: follower
*Node count: 32
*
$ echo stat | nc 10.81.12.141 2181
Zookeeper version: 3.2.1-808558, built on 08/27/2009 18:48 GMT
Clients:
 /10.81.12.152:58110[1](queued=0,recved=10374,sent=0)
 /10.81.13.173:35677[1](queued=0,recved=0,sent=0) *# it is caused by the nc
process*

Latency min/avg/max: 0/0/37
Received: 37128
Sent: 0
Outstanding: 0
Zxid: 0x1e000001f5
Mode: follower
*Node count: 26*

$ echo stat | nc 10.81.12.145 2181
Zookeeper version: 3.2.1-808558, built on 08/27/2009 18:48 GMT
Clients:
 /10.81.12.153:19130[1](queued=0,recved=10624,sent=0)
 /10.81.13.173:35678[1](queued=0,recved=0,sent=0) *# it is caused by the nc
process*

Latency min/avg/max: 0/2/213
Received: 26700
Sent: 0
Outstanding: 0
Zxid: 0x1e000001f5
Mode: leader
*Node count: 26*

The three 'stat' commands show different Node count! Just cannot understand
how it happened, can anyone give me some explanation about it?


-- 
With Regards!

Ye, Qian
Made in Zhejiang University

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