Re: Per-session memory footprint (9.0/windows) - Mailing list pgsql-general

From Scott Mead
Subject Re: Per-session memory footprint (9.0/windows)
Date
Msg-id AANLkTi=kum6SoQkCkXYdGVpWWaNnq16Qpe8_Vy5StZfb@mail.gmail.com
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In response to Per-session memory footprint (9.0/windows)  (Hannes Erven <hannes@erven.at>)
Responses Re: Per-session memory footprint (9.0/windows)  (Hannes Erven <hannes@erven.at>)
List pgsql-general


On Wed, Mar 2, 2011 at 11:07 AM, Hannes Erven <hannes@erven.at> wrote:
Folks,


I run a PG (currently 8.4, but will shortly migrate to 9.0) database on
Windows Server 2003 that supports a desktop application which opens a
few long-running sessions per user. This is due to the Hibernate
persistence layer and the "one session per view" pattern that is
recommended for such applications.
These sessions usually load a pile of data once to display to the user,
and then occasionally query updates of this data or even fetch single
rows over a long time (like a few hours).

It seems that each of the server postmaster.exe processes takes up
approx. 5 MB of server memory (the "virtual memory size" column in task
manager), and I guess this truly is the private memory these processes
require. This number is roughly the same for 8.4 and 9.0 .


Task manager is mis-leading as multiple processes are sharing memory.  You need process explorer http://technet.microsoft.com/en-us/sysinternals/bb896653 (or something like it) to see real memory consumption per backend.  Adding up the columns in task manager is wrong and most definitely scary if you believe it :-)

--Scott

 

As there are many, many such server processes running, is there anything
I can do to reduce/optimize the per-session memory footprint?

I'm aware of the sort_mem etc. parameters
(http://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server ) but
these seem to only apply to the execution of queries, not to sessions
that mainly "sit around waiting", right?


Thank you for any hints!

       -hannes

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