[pgpool-general: 3331] Re: Master/Slave (stream) mode - Memory depletion

[Christian Affolter]

Great, thanks a lot for looking into it.

Regards
Christian

On 03.12.2014 00:53, Tatsuo Ishii wrote:
> I was able to reproduce the problem with 3.4.0
> 
> 1) run pgbench -i
> 2) run pgbench -T 600  -S -c 1 -M extended test
> 3) run ps x as pgpool user and find pgpool process which is bound to the pgbench session #2
> 4) run ps and watch the process size like 'while true; do ps l 22942; sleep 1; done'
> 
> I see in #4, the process size increases rapidly:
> 1  1000 22942 22432  20   0 5145776 5109900 -   S    pts/25     1:14 pgpool: t-i
> F   UID   PID  PPID PRI  NI    VSZ   RSS WCHAN  STAT TTY        TIME COMMAND
> 1  1000 22942 22432  20   0 5170364 5134368 -   R    pts/25     1:15 pgpool: t-i
> F   UID   PID  PPID PRI  NI    VSZ   RSS WCHAN  STAT TTY        TIME COMMAND
> 1  1000 22942 22432  20   0 5194952 5159100 -   S    pts/25     1:15 pgpool: t-i
> F   UID   PID  PPID PRI  NI    VSZ   RSS WCHAN  STAT TTY        TIME COMMAND
> 1  1000 22942 22432  20   0 5227736 5187716 -   R    pts/25     1:16 pgpool: t-i
> F   UID   PID  PPID PRI  NI    VSZ   RSS WCHAN  STAT TTY        TIME COMMAND
> 1  1000 22942 22432  20   0 5252324 5212448 -   S    pts/25     1:16 pgpool: t-i
> 
> Note that even if I remove '-M extended' part (which means using
> extended protocol, i.e. prepare statements), I see the memory usage
> growing. So it seems this is nothing to do with whether prepared
> statement is used or not.
> 
> We will look into this.
> 
> Best regards,
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese:http://www.sraoss.co.jp
> 
>> Dear pgpool users
>>
>> I'm running two pgpool-II 3.4.0 instances in master/slave streaming
>> replication mode, with enabled watchdog and virtual IP control. In the
>> backend are two PostgreSQL 9.3.5 servers (one master and one slave)
>> involved. In the frontend are two Wildfly 8.1.0 application servers
>> having a xa-data-source configured, which connects to the VIP of the
>> pgpool instances.
>>
>> After around two days, the memory of the active pgpool-II instance (the
>> one holding the VIP) gets depleted completely and all the pgpool-II
>> processes together use around 6 GiB of memory until the kernels
>> out-of-memory manager kicks in or one stops the instance manually.
>>
>> The applications running within the Wildfly application servers are
>> proprietary, so I don't have access to the source code. What I see,
>> after turning statement logging on on the PostgreSQL server, is that the
>> following queries hit the master all two seconds from both servers:
>>
>> postgres[20069]: [86-1] LOG:  execute <unnamed>: select user0_.id as
>> id1_20_, user0_.company as company2_20_, user0_.created as created3_20_,
>> user0_.credentials_id as credent10_20_, user0_.email as email4_20_,
>> user0_.firstName as firstNam5_20_, user0_.lastModified as lastModi6_20_,
>> user0_.mergedTo as mergedTo7_20_, user0_.name as name8_20_,
>> user0_.organisation as organis11_20_, user0_.phone as phone9_20_ from
>> bcUser user0_ where user0_.email=$1
>> postgres[20069]: [86-2] DETAIL:  parameters: $1 = 'system at example.com'
>>
>> The queries are triggered from the HTTP load-balancer's alive-check,
>> which is executed every two seconds on one of the applications running
>> within the Wildfly servers.
>>
>> Does anyone have an idea why pgpool is allocating all the memory, or how
>> to further debug this?
>>
>> It would also be very helpful if anyone having a similar working setup
>> (Wildfly or JBoss) could share the data-source settings.
>>
>> There was a similar thread (3162 - Memory leaks) on the mailing list
>> around September [1].
>>
>>
>> Attached you will find an anonymised pgpool-II and xa-data-source
>> configuration, please let me know if you need more.
>>
>>
>> Many thanks in advance
>> Christian
>>
>>
>>
>> [1]
>> http://www.pgpool.net/pipermail/pgpool-general/2014-September/003204.html