[corosync] Why we send downlist and joinlist separately?

Yunkai Zhang qiushu.zyk at taobao.com
Thu Nov 3 10:05:04 GMT 2011

On Thu, Nov 3, 2011 at 5:37 PM, Angus Salkeld <asalkeld at redhat.com> wrote:
> On Thu, Nov 03, 2011 at 02:18:52PM +0800, Yunkai Zhang wrote:
>> Hi Angus:
>> I found that corosync sends downlist(alias leftlist in CPG) and
>> joinlist separately to CPG client after a new ring established.
>> When a node lefts from or joins into a ring, only downlist or joinlist
>> contain content, this behavior seems not strange.
>> But suppose there are two ring: Ring(A,B), Ring(C,D,E,F) that are
>> forming into a new ring, and these nodes: B,E,F dropped in the GATHER
>> state, then only these nodes: A,C,D will form the new Ring(A,C,D). And
>> corosync will send downlist(B) and joinlist(C,D) as two confchg events
>> to the CPG client of node A. This will make CPG client confused.
>> The correct way is that send _Only_ one confchg event containing both
>> downlist and joinlist to the CPG client. In this case,
>> 1) The CPG client of A should receive only one confchg as following:
>> memb:A,C,D       left:B         join:C,D
>> 2) The CPG client of C,D should receive only one confchg as following:
>> memb:A,C,D       left:E,F       join:A
>> Angus, what is your opinion?
>> If you agree with me, I would summit patch to fix it.
> Sure it would be better to have one event, just try leave
> cpg.c simpler and clearer than when you found it (it has a tendancy of getting
> more and more complex). Not always possible, but something to aim for.
> -Angus

Thanks, I will try it.

>> --
>> Yunkai Zhang
>> Work at Taobao
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Yunkai Zhang
Work at Taobao

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