[pgpool-hackers: 1269] Fw: [pgpool-II 0000162]: To start watchdog pgpool nodes simultaneously is not safe

[Yugo Nagata]

Hi Usama,

I have add a description about the problem into the documents of
3.2, 3.3. and 3.4.

http://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=68cbdd88477f8294cab0324d627f8cff213df958

Do you know whether this problem occurs in watchdog of 3.5? If so,
I'll commit the same to master.

Begin forwarded message:

Date: Fri, 25 Dec 2015 13:13:43 +0900
From: pgpool Bug Tracker <bugtracker at pgpool.net>
To: nagata at sraoss.co.jp
Subject: [pgpool-II 0000162]: To start watchdog pgpool nodes simultaneously is not safe



The following issue has been ASSIGNED. 
====================================================================== 
http://www.pgpool.net/mantisbt/view.php?id=162 
====================================================================== 
Reported By:                harukat
Assigned To:                nagata
====================================================================== 
Project:                    pgpool-II
Issue ID:                   162
Category:                   Bug
Reproducibility:            always
Severity:                   minor
Priority:                   normal
Status:                     assigned
====================================================================== 
Date Submitted:             2015-12-20 20:28 JST
Last Modified:              2015-12-25 13:13 JST
====================================================================== 
Summary:                    To start watchdog pgpool nodes simultaneously is not
safe
Description: 
To start watchdog pgpool nodes simultaneously is not safe.
There is the case that the following happens.

- "FATAL: failed to initialize watchdog, delegate_IP "x.x.x.x" already exists"
- Master nodes more than two are born
- The recognitions of the invalid node are not consistent.

There are not robust initial coordination logic.
So I think that we describe clearly "must start it one by one" to the manual.


Steps to Reproduce: 
Tested version: pgpool2-V3_4_STABLE-3d2093e (snapshot at 2015-12-20) + patch

The patch file improves 'DETAIL:  connect() reports failure "Success"',
but it isn't related to this main issue.

I set up the following watchdog cluster and started 4 pgpools simultaneously.
(pg1, pg2 ... are hostname in my test environment)

 [pg1 (pgpool)] ---------+- [pg3 (PostgreSQL)]
 [pg2 (pgpool)] ---------+
 [pgpool1 (pgpool)] -----+
 [pgpool2 (pgpool)] -----+

====================================================================== 

Issue History 
Date Modified    Username       Field                    Change               
====================================================================== 
2015-12-20 20:28 harukat        New Issue                                    
2015-12-20 20:28 harukat        File Added: pgpool_conf_and_patch.zip           
        
2015-12-25 13:13 t-ishii        Assigned To               => nagata          
2015-12-25 13:13 t-ishii        Status                   new => assigned     
2015-12-25 13:13 t-ishii        Description Updated                          
2015-12-25 13:13 t-ishii        Steps to Reproduce Updated                    
======================================================================



-- 
Yugo Nagata <nagata at sraoss.co.jp>