[pgpool-general: 428] Re: strange load balancing issue in Solaris

[Aravinth]

Hi,

The code you have sent is same in child.c.

I have attached the log file. Please check


--Aravinth


On Tue, May 8, 2012 at 6:20 AM, Tatsuo Ishii <ishii at postgresql.org> wrote:

> I suspect there's some portablity issue with load balance code. The
> actual source code is in select_load_balancing_nodechild.c).
> Please modify source code and connect to pgpool by using psql.
> Please send the log output.
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese: http://www.sraoss.co.jp
>
> int select_load_balancing_node(void)
> {
>        int selected_slot;
>        double total_weight,r;
>        int i;
>
>        /* choose a backend in random manner with weight */
>        selected_slot = MASTER_NODE_ID;
>        total_weight = 0.0;
>
>        for (i=0;i<NUM_BACKENDS;i++)
>        {
>                if (VALID_BACKEND(i))
>                {
>                        total_weight += BACKEND_INFO(i).backend_weight;
>                }
>        }
>        r = (((double)random())/RAND_MAX) * total_weight;
>        pool_log("r: %f total_weight: %f", r, total_weight);            <--
> add this
>
>        total_weight = 0.0;
>        for (i=0;i<NUM_BACKENDS;i++)
>        {
>                if (VALID_BACKEND(i) && BACKEND_INFO(i).backend_weight >
> 0.0)
>                {
>                        if(r >= total_weight)
>                                selected_slot = i;
>                        else
>                                break;
>                        total_weight += BACKEND_INFO(i).backend_weight;
>                 }
>        }
>
>        pool_debug("select_load_balancing_node: selected backend id is %d",
> selected_slot);
>         return selected_slot;
> }
>
>
> > Hi Tatsuo, Thanks for the reply.
> >
> > The normalized weights are 0.5 for both nodes and the selected node is
> always the same node. I hope then it's srandom().
> >
> >
> > Any idea to solve this srandom issue
> >
> >
> > Thanks and Regards,
> > Aravinth
> >
> >
> > ________________________________
> >  From: Tatsuo Ishii <ishii at postgresql.org>
> > To: aravinth at mafiree.com
> > Cc: pgpool-general at pgpool.net
> > Sent: Tuesday, May 1, 2012 4:41 AM
> > Subject: Re: [pgpool-general: 396] strange load balancing issue in
> Solaris
> >
> > First of all please check "normalized" weights are as you expected.
> > Run "show pool_status;" and see "backend_weight0", "backend_weight1"
> > section. You see a floating point numbers, which are the normalized
> > weight between 0.0 and 1.0. If you see both are 0.5, primary and
> > standby are given same weight.
> >
> > If they are ok, I suspect srandom() function behavior is different
> > from other platforms. Pgpool-II chooses the load balance node by using
> > srandom(). select_load_balancing_node() is the function which is
> > responsible for selecting the load balance node. If you run pgpool-II
> > with -d (debug) option, you will see following in the log:
> >
> >     pool_debug("select_load_balancing_node: selected backend id is %d",
> selected_slot);
> >
> > If backend_weight in show pool_status are fine but the line above
> > always shows same number, it is the sign that we have problem with
> > srandom().
> > --
> > Tatsuo Ishii
> > SRA OSS, Inc. Japan
> > English: http://www.sraoss.co.jp/index_en.php
> > Japanese: http://www.sraoss.co.jp
> >
> >> Hi All,
> >>
> >> I am facing a strange issue in load balancing with replication mode set
> to
> >> true in Solaris. Load balancing algorithm always select the same node
> >> whatever may be the backend weight
> >>
> >> Here is the scenario.
> >>
> >> I have a pgpool installed installed in 1 server
> >> 2 postgres nodes in other 2 servers
> >> replication mode set to true and load balancing set to true
> >> backend weight of the 2 nodes is 1.
> >>
> >> When I fire the queries manuall using different connections or using
> >> pgbench all the queries hit the same node. Load balancing algorithm
> always
> >> select the same node.
> >> No effect in changing the backend weight. Only when I set backend
> weight to
> >> 0 hits go to the other server.
> >>
> >>
> >> I face this issue only in solaris. The same setup in other servers (
> centos
> >> ,RHEL, ubunt etc) does the load balancing perfectly.
> >>
> >> Also tries various postgres versions and pgpool version with same
> result.
> >> But every version runs fine in other servers.
> >>
> >> Has anyone faced this issue?
> >>
> >> Any information would highly helpful.
> >>
> >> Regards,
> >> Aravinth
> _______________________________________________
> pgpool-general mailing list
> pgpool-general at pgpool.net
> http://www.pgpool.net/mailman/listinfo/pgpool-general
>
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