> Sorry if this is the wrong list, but I've been stuck for a couple days
> now. I tried pgpool-general but that list appears to not like me.
> I'm not getting any posts and my post hasn't shown up in the archives.
I am the admin of the list. Please contact me directly if you need
help on this.
> I have a Python/Django app that will require database load balancing
> at some point in the near future. In the meantime I'm trying to learn
> to implement pgpool on a local virtual machine setup.
>
> I have 4 Ubuntu 12.04 VMs:
>
> 192.168.1.80 <- pool, pgppool2 installed and accessible
> 192.168.1.81 <- db1 master
> 192.168.1.82 <- db2 slave
> 192.168.1.83 <- db3 slave
>
> I have pgpool-II version 3.1.1 and my database servers are running
> PostgreSQL 9.1.
>
> I have my app's db connection pointed to 192.168.1.80:9999 and it works fine.
>
> The problem is when I use Apache ab to throw some load at it, none of
> SELECT queries appear to be balanced. All the load goes to my db1
> master. Also, very concerning is the load on the pool server itself,
> it is really high compared to db1, maybe an average of 8-10 times
> higher. Meanwhile my db2 and db3 servers have a load of nearly zero,
> they appear to only be replicating from db1, which isn't very load
> intensive for my tests with ab.
>
> ab -n 300 -c 4 -C 'sessionid=80a5fd3b6bb59051515e734326735f80'
> http://192.168.1.17/contacts/
>
> That drives the load on my pool server up to about 2.3. Load on db1
> is about 0.4 and load on db2 and db3 is nearly zero.
>
> Can someone take a look at my pgpool.conf and see if what I'm doing wrong?
>
> http://pastebin.com/raw.php?i=wzBc0aSp
>
>
> I'm starting to think maybe it has something to do with Django
> wrapping every request in a transaction by default, but when the
> transaction only has SELECTs, shouldn't that be load balanced just
> fine? Makes my stomach hurt to think I may have to turn off
> auto-commit and manually commit transactions all throughout my code :(
> Still hoping it's a pgpool setup issue, since it's my first time
> setting it up and all.
Yes, your guess is correct. In replication mode, the SELECTs should
not be in an explicit transaction if you want them load balanced (if
you run pgpool-II in streaming replication mode, the restriction is
not applied).
Is it possible to turn off auto-start-transaction of Django? Pgpool-II
already wraps every write SQL statements in a trasaction.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp
