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Message-ID: <1525066983.2466.5.camel@cybertec.at>
Subject: Re: vacuumdb causes memory drain.
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: Sushil Shirodkar <sushilps@hotmail.com>
Cc: "don@seiler.us" <don@seiler.us>, "pgsql-admin@postgresql.org"
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Date: Mon, 30 Apr 2018 07:43:03 +0200
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Sushil Shirodkar wrote:
> > > > > > > On Thu, Apr 26, 2018 at 10:31 AM, Sushil Shirodkar <sushilps@hotmail.com> wrote:
> > > > > > > Running "vacuumdb -a -z -v" from the cron on one of our test environment, and 
> > > > > > > noticed that memory of the server goes down from 3.4GB free to 150MB.  Once 
> > > > > > > the process is over, memory is not released, is it normal or something needs to be 
> > > > > > > changed ? also other processes start running slow afterwards due to low memory.  
>
> Process which was running close to 99% memory was
>  "/usr/lib/postgresql/9.5/bin/postgres -D /var/lib/postgresql/9.5/main -c config_file=/etc/postgresql/9.5/main/postgresql.conf"
> 
> free -h - was showing between 100-150 mb free. 
> 
> shared_buffers = 1GB
> maintenance_work_mem = 256MB

Can you share the "free -h" output?

What do you get for
ps -p <postmaster PID> -o rss,trs,drs,vsz,%mem
if you substitute the postmaster's process ID?

If you say that "sync" restored normal behavior, are you implying that there
was a high I/O load?

Still trying to figure out what exactly you are experiencing.

Yours,
Laurenz Albe
-- 
Cybertec | https://www.cybertec-postgresql.com