Re: Postgres filling up hard drive with swap files

From: Joe Lester <joe_lester(at)sweetwater(dot)com>
To: postgres list <pgsql-general(at)postgresql(dot)org>
Cc: Jeff <threshar(at)torgo(dot)978(dot)org>, Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
Subject: Re: Postgres filling up hard drive with swap files
Date: 2004-08-20 19:18:43
Message-ID: C0517E07-F2DD-11D8-BDD7-000A95A58EA0@sweetwater.com
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> On osx the number to look at isn't vsize, but actually rprvt. vsize
> is its size in virtual memory (basically useless)- rprvt is the size
> of its "private memory" - non shared memory. It is a pretty good
> number to go by.
> But I believe the whole problem is the emac only has 512MB of ram and
> you simply don't have enough memory for that many connections. Even
> with each connection sucking up 2MB of memory that is 400MB and as you
> can see.. most of them are sucking 4-8MB.

Thanks for the response, Jeff. The RPRVT, which you say is best to go
by, shows only 4K-2MB per connection. That's less than the 4-8MB size
you reference which I believe comes from the RSIZE column in top. So
according to RSIZE I should add more RAM. But according to RPRVT I
should be OK with 512 MB of RAM. I'm a little confused on which column
to go by.

Also, even if I need to add more RAM, it still strikes me as more than
a little weird that a memory overflow situation gradually eats up all
the space on my hard drive. That's the problem I'd really like to solve
if possible.

PID COMMAND %CPU TIME #TH #PRTS #MREGS RPRVT RSHRD RSIZE
VSIZE
14378 postgres 0.0% 0:00.41 1 9 33 880K 17.8M 8.31M
60.0M
14359 postgres 0.0% 0:00.90 1 9 32 860K 17.8M 4.12M
59.5M
14346 postgres 0.0% 0:00.31 1 9 32 840K 17.8M 2.26M
59.5M
14342 postgres 0.0% 0:01.08 1 9 33 880K 17.8M 7.86M
60.0M
14290 postgres 0.0% 0:00.55 1 9 32 868K 17.8M 3.09M
59.5M
14235 postgres 0.0% 0:03.39 1 9 33 880K 17.8M 7.68M
60.0M
14224 postgres 0.0% 0:00.43 1 9 32 864K 17.8M 2.55M
59.5M
14220 postgres 0.0% 0:00.40 1 9 33 888K 17.8M 3.02M
60.0M
14218 postgres 0.0% 1:07.53 1 9 33 2.04M 17.8M 10.9M
60.0M
14075 postgres 0.0% 1:40.98 1 9 33 872K 17.8M 10.5M
60.0M
14063 postgres 0.0% 0:00.55 1 9 33 892K 17.8M 3.27M
60.0M

> If you cannot upgrade I'd recommend looking into something like pgpool
> so you can pool your connections (this results in having a lot fewer
> instances of postgres, thus saving tons of memory)

Huh. Cool. Do you have any experience of what the performance hit would
be for using pgpool?

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