[pgpool-general: 5652] Re: oom when memory_cache_enabled is on

[Tatsuo Ishii]

> Hello, Tatsuo.
> 
> Thank you very much!
> Does it mean that 3.6.4 is not affected by this bug?

Not sure. I just confirmed 3.6.1 has small leak (much smaller than 3.6.5).
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp

> You wrote 28 июля 2017 г., 11:17:36:
> 
>> I was able to confirm the memory leak with following conditions met:
> 
>> 1) Pgpool-II 3.6/5 or newer
>> 2) streaming replication mode
>> 3) extended queries are used
> 
>> I will look into this issue.
> 
>> Best regards,
>> --
>> Tatsuo Ishii
>> SRA OSS, Inc. Japan
>> English: http://www.sraoss.co.jp/index_en.php
>> Japanese:http://www.sraoss.co.jp
> 
>>> Hello.
>>> 
>>> We started testing our project under heavy load and encountered out of
>>> memory  condition  if pgpool is running with memory_cache_enabled=on, both
>>> with shmem and memcached.
>>> 
>>> Under simulated heavy load pgpool consumes all available memory (16Gb)
>>> in just a few minutes and then kernel kills it.
>>> 
>>> I've found this old similar bug thread: http://www.pgpool.net/mantisbt/view.php?id=52
>>> and  tried  running  pgpool  with  valgrind,  but (perhaps due to high
>>> number  of pgpool childs?) system was almost unresponsive and i had to
>>> restart pgpool without valgrind.
>>> 
>>> I'm  attaching pgpool log which was written during the short period of
>>> valgrind activity.
>>> There  are some records, but I have zero experience in this area and I
>>> have  no  idea  if  they  are  indicating a problem or not. One of the
>>> records:
>>> Jul 26 09:27:59 ip-172-31-26-132 pgpool2[3707]: ==4612==    at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
>>> Jul 26 09:27:59 ip-172-31-26-132 pgpool2[3707]: ==4612==    by 0x448063: save_ps_display_args (ps_status.c:173)
>>> Jul 26 09:27:59 ip-172-31-26-132 pgpool2[3707]: ==4612==    by 0x407F41: main (main.c:192)
>>> Jul 26 09:27:59 ip-172-31-26-132 pgpool2[3707]: ==4612==
>>> Jul 26 09:27:59 ip-172-31-26-132 pgpool2[3707]: ==4612== LEAK SUMMARY:
>>> Jul 26 09:27:59 ip-172-31-26-132 pgpool2[3707]: ==4612==    definitely lost: 96 bytes in 1 blocks
>>> Jul 26 09:27:59 ip-172-31-26-132 pgpool2[3707]: ==4612==    indirectly lost: 343 bytes in 11 blocks
>>> Jul 26 09:27:59 ip-172-31-26-132 pgpool2[3707]: ==4612==      possibly lost: 0 bytes in 0 blocks
>>> Jul 26 09:27:59 ip-172-31-26-132 pgpool2[3707]: ==4612==    still reachable: 254,475 bytes in 3,102 blocks
>>> Jul 26 09:27:59 ip-172-31-26-132 pgpool2[3707]: ==4612==         suppressed: 0 bytes in 0 blocks
>>> Jul 26 09:27:59 ip-172-31-26-132 pgpool2[3707]: ==4612== Reachable blocks (those to which a pointer was found) are not shown.
>>> Jul 26 09:27:59 ip-172-31-26-132 pgpool2[3707]: ==4612== To see them, rerun with: --leak-check=full --show-leak-kinds=all
>>> Jul 26 09:27:59 ip-172-31-26-132 pgpool2[3707]: ==4612==
>>> Jul 26 09:27:59 ip-172-31-26-132 pgpool2[3707]: ==4612== For counts of detected and suppressed errors, rerun with: -v
>>> Jul 26 09:27:59 ip-172-31-26-132 pgpool2[3707]: ==4612== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
>>> 
>>> 
>>> 
>>> "ulimit  -a"  output  of  user  postgres (pgpool is running under this
>>> account):
>>> postgres at ip-172-31-26-132:~$ ulimit -a
>>> core file size          (blocks, -c) 0
>>> data seg size           (kbytes, -d) unlimited
>>> scheduling priority             (-e) 0
>>> file size               (blocks, -f) unlimited
>>> pending signals                 (-i) 64124
>>> max locked memory       (kbytes, -l) 64
>>> max memory size         (kbytes, -m) unlimited
>>> open files                      (-n) 10000
>>> pipe size            (512 bytes, -p) 8
>>> POSIX message queues     (bytes, -q) 819200
>>> real-time priority              (-r) 0
>>> stack size              (kbytes, -s) 8192
>>> cpu time               (seconds, -t) unlimited
>>> max user processes              (-u) 64124
>>> virtual memory          (kbytes, -v) unlimited
>>> file locks                      (-x) unlimited
>>> 
>>> 
>>> 
>>> 
>>> -- 
>>> Best regards,
>>>  Pavel                          mailto:balroga3 at yandex.ru
> 
> 
> 
> -- 
> Best regards,
>  Pavel                          mailto:balroga3 at yandex.ru
>