Re: BUG #14606: Memory usage continue to increase

Today I tried a performance testing again, after performance testing is
finished, found memory usage increased about 170MB, then enter the
Postgresql docker container, executed command "/usr/bin/top -bcn 1", found
there are some new idle Postgres processes as below, the memory of other
processed haven't been added, it looks like these new added idle process
caused the memory usage of Postgresql server is added. Don't know what
these idle postgres processed for, and they didn't disappear after 2 hours.

9766 postgres 10 -10 272776 9020 7236 S 0.0 0.0 0:00.00
postgres: 8wk48fzjxrrkd0hj unpyxldeefjqvm1a 10.0.16.4(39698) idle

9767 postgres 10 -10 272776 9020 7236 S 0.0 0.0 0:00.00
postgres: 8wk48fzjxrrkd0hj unpyxldeefjqvm1a 10.0.16.4(39700) idle

...

9768 postgres 10 -10 272776 9020 7236 S 0.0 0.0 0:00.00
postgres: 8wk48fzjxrrkd0hj unpyxldeefjqvm1a 10.0.16.4(39702) idle

9769 postgres 10 -10 272776 9020 7236 S 0.0 0.0 0:00.00
postgres: 8wk48fzjxrrkd0hj unpyxldeefjqvm1a 10.0.16.4(39704) idle

On Fri, Mar 31, 2017 at 11:58 AM, Kyotaro HORIGUCHI <
horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote:

> At Fri, 31 Mar 2017 00:30:31 +0800, Sam Dai <sam(dot)dai(at)servicemax(dot)com>
> wrote in <CAO+pR0oYSFNgx_oAYxLyNOVmh7R0oG52v3cU0Dq1mkTs
> QLbqGQ(at)mail(dot)gmail(dot)com>
> > Is it possible this issue is caused by the cache or buffer of Postgresql
> > server? I guess when we run performance testing, will read/update
> > different records, Postgresql might use some new memory for cache or
> buffer
> > some records, and some these cache or buffer will not be cleaned after
> > performance test is finished. so the new increased memory is for cache or
> > buffer.
> > Not sure if my guess is reasonable or not.
>
> Anyway at least the amount of syscache should be revealed on SQL
> interface. It is not even managed on builds without defining
> CATCACHE_STATS.
>
> For your information, the discussion about syscache bloat is
> here.
>
> https://www.postgresql.org/message-id/214653D8DF574BFEAA6ED53E545E99
> E4%40maumau
> https://www.postgresql.org/message-id/20161219.201505.
> 11562604(dot)horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp
>
> In breaf, the bloat in the above threads is caused by accesing
> many-many nonexistent tables, columns, functions or other SQL
> objects. If you did something like that on a long-standing
> connection, it is likely to be this issue.
>
> If the "buffer" means shared_buffer, it cannot bloat. I'm not
> sure about other kinds of memory leak but I belive there's no
> known significant memory leak at present.
>
> > Thanks,
> > Sam
> >
> > On Thu, Mar 30, 2017 at 9:42 PM, Sam Dai <sam(dot)dai(at)servicemax(dot)com> wrote:
> >
> > > I run Postgresql server in docker container, I run command "docker
> stats"
> > > to measure memory , for example in the below command result, the
> memory
> > > usage of docker container is 1.413 GB.
> > >
> > > c137012d8af9 793.64% 1.413 GB / 67.55 GB 2.09%
> > > 5.927 GB / 7.249 GB 0 B / 10.32 GB 0
> > >
> > > Thanks,
> > >
> > > Sam
> > >
> > >
> > >
> > > On Thu, Mar 30, 2017 at 9:32 PM, Michael Paquier <
> > > michael(dot)paquier(at)gmail(dot)com> wrote:
> > >
> > >> On Thu, Mar 30, 2017 at 10:24 PM, Sam Dai <sam(dot)dai(at)servicemax(dot)com>
> wrote:
> > >>
> > >> (please do not top-post, this breaks the thread logic)
> > >>
> > >> > My application used ComboPooledDataSource to connect to Postgresql
> > >> server,
> > >> > the setting is as below, if this issue is syscache bloat, what is
> the
> > >> > solution of this issue?
> > >>
> > >> Just a question: how are you measuring memory?
> > >>
> > >> > <property name="maxConnectionAge" value="300" /> <!-- 5 min -->
> > >> > <property name="maxIdleTime" value="180" /> <!-- 3 min -->
> > >>
> > >> Seeing that, likely this is not syscache.
>
> I agree with you. It's unlikely to happen in such a short time.
>
> regards,
>
> --
> Kyotaro Horiguchi
> NTT Open Source Software Center
>
>