[pgpool-general: 4334] Re: Connection Pool

[Derek]

Thanks, I'll give it go.

Kind regards,
Derek.

On 18 Jan 2016, at 1:30 PM, Tatsuo Ishii <ishii at postgresql.org> wrote:

>> Hi Tatsuo,
>> Attached is the pgpool.conf file that I used.  Please review and let me know how I can prevent the connection pool issue below.
>> Kind Regards,Derek.
>> 
>> 
>>    On Friday, 15 January 2016, 13:09, Derek <derek_kouch at yahoo.com.au> wrote:
>> 
>> 
>> I'll try to send early next week.
>> 
>> Kind regards,
>> Derek.
>> 
>>> On 15 Jan 2016, at 11:15 AM, Tatsuo Ishii <ishii at postgresql.org> wrote:
>>> 
>>> Connection pooling behavior depends on pgpool.conf.  Can we share it?
>>> 
>>> Best regards,
>>> --
>>> Tatsuo Ishii
>>> SRA OSS, Inc. Japan
>>> English: http://www.sraoss.co.jp/index_en.php
>>> Japanese:http://www.sraoss.co.jp/
>>> 
>>>> Hi,
>>>> 
>>>> I'm trying to understand how the connection pool works. Whether I'm getting a connection leak.
>>>> 
>>>> Pgpool v3.4
>>>> Postgres v9.3.10
>>>> Rhel v7.1
>>>> 
>>>> I have 2 applications, the first application A monitors postgres via pgpool. It connects and disconnects continuously every few minutes. The second is an application B that starts up in the morning and stays connected for the whole day, and shutdowns down at night. Both applications use different user accounts to log into Postgres.
>>>> 
>>>> What I've noticed is that in pgpool admin it shows that there are processes that share the same connection even though the username/database/client ip connection combo is different. Though one shows front end connected (app B) and the other is disconnected (app A). Is this ok?
>>>> 
>>>> On the pgpool box, it only shows the connected application B in the list of processes.
> 
> Yes, it makes sense.
> 
> It is possible that a pgpool process holds connections to backend with
> different username/database pair, up to 4, because you set max_pool to
> 4.
> 
> However no more than 1 client can connect to the pgpool process at the
> same time. So you only see B connects to pgpool.
> 
>>>> On the Postgres box, it shows both the disconnected app A and the connected app B. I think it is due to what is shown in pgpoolAdmin. The disconnect app A holds an open database connection, even though the app A is no longer running. This connection doesn't disconnect until app B does.
> 
> This is because you set child_life_time to 300. I think what happens
> here is, after A and B are disconnected, pgpool goes into idle state
> and sucides after 300 seconds.
> 
>>>> How can I stop this from happening?
> 
> If you want to stop the connections from pgpool to backend after A (or
> B) disconnects to pgpool, you could set connection_life_time to non 0.
> If you set it to 30, for example, the connection to backend will be
> disconnected after it is idle for 30 seconds.
> 
>>>> Kind regards,
>>>> Derek.
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>> 
>>