[pgpool-general: 5782] After failback, standby goes to primary, and primary goes to standy

[Lucas Luengas]

Hello
I am testing Pgpool 3.4.13 with Postgresql-9.6, with streaming replication
and watchdog, on Centos 7. I have two server. Every server has installed
Pgpool and Postgresql. I have installed pgpool from yum repository.

Node 0 is primary, with status 2
Node 1 is standby, with status 2

If Postgresql service is stopped in node 0, then:
node 0 is standby, with status 3
node 1 is primary, with status 2. (failover)

Then, Postgresql service is started in node 0.
node 0 is standby, with status 3
node 1 is primary, with status 2

Then, I attach node 0 using pcp_attach_node command.
node 0 is primary, with status 2.
node 1 is standby, with status 2.
Node 0 was changed to primary and node 1 was changed to standby. Why ? Do I
have any error in my setup?
I think the correct result should be:
node 0 is standby, with status 2
node 1 is primary, with status 2

I have repeated previous steps with pgpool 3.4.12, 3,4.11, 3.4.10 and 3.4.9
with same configuration and same server. I get same results.
Also, I have repeated step with pgpool 3.6.6 and I get same results.

Some log lines during fallback

Oct 20 13:41:03 localhost pgpool[9687]: [128-1] 2017-10-20 13:41:03: pid
9687: LOG:  received failback request for node_id: 0 from pid [9687]
Oct 20 13:41:03 localhost pgpool[4913]: [255-1] 2017-10-20 13:41:03: pid
4913: LOG:  watchdog notifying to start interlocking
Oct 20 13:41:03 localhost pgpool[4913]: [256-1] 2017-10-20 13:41:03: pid
4913: LOG:  starting fail back. reconnect host 192.168.0.136(5432)
Oct 20 13:41:03 localhost pgpool[4913]: [257-1] 2017-10-20 13:41:03: pid
4913: LOG:  Node 1 is not down (status: 2)
Oct 20 13:41:04 localhost pgpool[4913]: [258-1] 2017-10-20 13:41:04: pid
4913: LOG:  Do not restart children because we are failbacking node id 0
host: 192.168.0.136 port: 5432 and we are in streaming replication mode and
not all backends were down
Oct 20 13:41:04 localhost pgpool[4913]: [259-1] 2017-10-20 13:41:04: pid
4913: LOG:  find_primary_node_repeatedly: waiting for finding a primary node
Oct 20 13:41:04 localhost pgpool[4913]: [260-1] 2017-10-20 13:41:04: pid
4913: LOG:  find_primary_node: checking backend no 0
Oct 20 13:41:04 localhost pgpool[4913]: [260-2]
Oct 20 13:41:04 localhost pgpool[4913]: [261-1] 2017-10-20 13:41:04: pid
4913: LOG:  find_primary_node: primary node id is 0
Oct 20 13:41:04 localhost pgpool[4913]: [262-1] 2017-10-20 13:41:04: pid
4913: LOG:  watchdog notifying to end interlocking
Oct 20 13:41:04 localhost pgpool[4913]: [263-1] 2017-10-20 13:41:04: pid
4913: LOG:  failover: set new primary node: 0
Oct 20 13:41:04 localhost pgpool[4913]: [264-1] 2017-10-20 13:41:04: pid
4913: LOG:  failover: set new master node: 0
Oct 20 13:41:04 localhost pgpool[4913]: [265-1] 2017-10-20 13:41:04: pid
4913: LOG:  failback done. reconnect host 192.168.0.136(5432)
Oct 20 13:41:04 localhost pgpool[9688]: [194-1] 2017-10-20 13:41:04: pid
9688: LOG:  worker process received restart request
Oct 20 13:41:05 localhost pgpool[9687]: [129-1] 2017-10-20 13:41:05: pid
9687: LOG:  restart request received in pcp child process
Oct 20 13:41:05 localhost pgpool[4913]: [266-1] 2017-10-20 13:41:05: pid
4913: LOG:  PCP child 9687 exits with status 256 in failover()
Oct 20 13:41:05 localhost pgpool[4913]: [267-1] 2017-10-20 13:41:05: pid
4913: LOG:  fork a new PCP child pid 10410 in failover()
Oct 20 13:41:05 localhost pgpool[4913]: [268-1] 2017-10-20 13:41:05: pid
4913: LOG:  worker child process with pid: 9688 exits with status 256
Oct 20 13:41:05 localhost pgpool[4913]: [269-1] 2017-10-20 13:41:05: pid
4913: LOG:  fork a new worker child process with pid: 10411
Oct 20 13:41:10 localhost pgpool[9692]: [202-1] 2017-10-20 13:41:10: pid
9692: LOG:  selecting backend connection
Oct 20 13:41:10 localhost pgpool[9692]: [202-2] 2017-10-20 13:41:10: pid
9692: DETAIL:  failback event detected, discarding existing connections

Kind regards
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