[pgpool-general: 5648] Re: oom when memory_cache_enabled is on
Tatsuo Ishii
ishii at sraoss.co.jp
Fri Jul 28 08:05:37 JST 2017
To fire child_max_connections, your client needs to reconnect to
Pgpool-II. Just sending many selects does not trigger it.
Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp
> I've tried to force pgpool to restart its child processes by setting
> really low numbers in child_max_connections, for example
> child_max_connections = 10
> but still even after serving more than 200k selects with
> max_init_children = 500 all pgpool child processes' pids are the
> same as they were right after pgpool start.
>
> Does it mean that pgpool didn't restart any of its childs or is this
> an expected behaviour and child's pid is not supposed to change when
> pgpool restarts its child process?
>
>
>> 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
>
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