[Pacemaker] pre_notify_demote is issued twice

[Andrew Beekhof]

On 21 Feb 2014, at 2:19 pm, Andrew Beekhof <andrew at beekhof.net> wrote:

> 
> On 18 Feb 2014, at 1:23 pm, Andrew Beekhof <andrew at beekhof.net> wrote:
> 
>> 
>> On 6 Feb 2014, at 7:45 pm, Keisuke MORI <keisuke.mori+ha at gmail.com> wrote:
>> 
>>> Hi,
>>> 
>>> I observed that pre_notify_demote is issued twice when a master
>>> resource is migrating.
>>> I'm wondering if this is the correct behavior.
>>> 
>>> Steps to reproduce:
>>> 
>>> - Start up 2 nodes cluster configured for the PostgreSQL streaming
>>> replication using pgsql RA as  a master/slave resource.
>>> - kill the postgresql process on the master node to induce a fail-over.
>>> - The fail-over succeeds as expected, but pre_notify_demote was
>>> executed twice on each node before demoting on the master resource.
>>> 
>>> 100% reproducible on my cluster.
>>> 
>>> Pacemaker version: 1.1.11-rc4 (source build from the repo)
>>> OS: RHEL6.4
>>> 
>>> I have never seen this on Pacemaker-1.0.* cluster with the same configuration.
>>> 
>>> The relevant logs and pe-inputs are attached.
>>> 
>>> 
>>> Diagnostics:
>>> 
>>> (1) The first transition caused by the process failure (pe-input-160)
>>> initiates pre_notify_demote on both nodes and cancelling slave monitor
>>> on the slave node.
>>> {{{
>>> 171 Jan 30 16:08:59 rhel64-1 crmd[8143]:   notice: te_rsc_command:
>>> Initiating action 9: cancel prmPostgresql_cancel_10000 on rhel64-2
>>> 172 Jan 30 16:08:59 rhel64-1 crmd[8143]:   notice: te_rsc_command:
>>> Initiating action 79: notify prmPostgresql_pre_notify_demote_0 on
>>> rhel64-1 (local)
>>> 
>>> 175 Jan 30 16:08:59 rhel64-1 crmd[8143]:   notice: te_rsc_command:
>>> Initiating action 81: notify prmPostgresql_pre_notify_demote_0 on
>>> rhel64-2
>>> }}}
>>> 
>>> (2) When cancelling slave monitor completes, the transition is aborted
>>> by Resource op removal.
>>> {{{
>>> 176 Jan 30 16:08:59 rhel64-1 crmd[8143]:     info: match_graph_event:
>>> Action prmPostgresql_monitor_10000 (9) confirmed on rhel64-2 (rc=0)
>>> 177 Jan 30 16:08:59 rhel64-1 cib[8138]:     info: cib_process_request:
>>> Completed cib_delete operation for section status: OK (rc=0,
>>> origin=rhel64-2/crmd/21, version=0.37.9)
>>> 178 Jan 30 16:08:59 rhel64-1 crmd[8143]:     info:
>>> abort_transition_graph: te_update_diff:258 - Triggered transition
>>> abort (complete=0, node=rhel64-2, tag=lrm_rsc_op,
>>> id=prmPostgresql_monitor_10000,
>>> magic=0:0;26:12:0:acf9a2a3-307c-460b-b786-fc20e6b8aad5, cib=0.37.9) :
>>> Resource op removal
>>> }}}
>>> 
>>> (3) The second transition is calculated by the abort (pe-input-161)
>>> which results initiating pre_notify_demote again.
>> 
>> If the demote didn't complete (or wasn't even attempted), then we must send the pre_notify_demote again unfortunately.
>> The real bug may well be that the transition shouldn't have been aborted.
> 
> It looks legitimate:
> 
> Jan 30 16:08:59 rhel64-1 crmd[8143]:     info: abort_transition_graph: te_update_diff:258 - Triggered transition abort (complete=0, node=rhel64-2, tag=lrm_rsc_op, id=prmPostgresql_monitor_10000, magic=0:0;26:12:0:acf9a2a3-307c-460b-b786-fc20e6b8aad5, cib=0.37.9) : Resource op removal

It looks like get_cancel_action() was not functioning correctly:

   https://github.com/beekhof/pacemaker/commit/9d77c99

> 
> Jan 30 16:08:59 rhel64-1 cib[8138]:     info: cib_process_request: Completed cib_delete operation for section status: OK (rc=0, origin=rhel64-2/crmd/21, version=0.37.9)
> 
> It looks like part of the node status entry being removed for rhel64-2.
> Possibly as a result of:
> 
> Jan 30 16:07:54 rhel64-2 crmd[25070]:     info: erase_status_tag: Deleting xpath: //node_state[@uname='rhel64-2']/transient_attributes
> 
> The new cib code, being much faster, might help here too :)
> 
>> 
>>> {{{
>>> 227 Jan 30 16:09:01 rhel64-1 pengine[8142]:   notice:
>>> process_pe_message: Calculated Transition 15:
>>> /var/lib/pacemaker/pengine/pe-input-161.bz2
>>> 229 Jan 30 16:09:01 rhel64-1 crmd[8143]:   notice: te_rsc_command:
>>> Initiating action 78: notify prmPostgresql_pre_notify_demote_0 on
>>> rhel64-1 (local)
>>> 232 Jan 30 16:09:01 rhel64-1 crmd[8143]:   notice: te_rsc_command:
>>> Initiating action 80: notify prmPostgresql_pre_notify_demote_0 on
>>> rhel64-2
>>> }}}
>>> 
>>> I think that the transition abort at (2) should not happen.
>>> 
>>> Regards,
>>> -- 
>>> Keisuke MORI
>>> <logs-pre-notify-20140206.tar.bz2>_______________________________________________
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