[pgpool-general: 3981] Re: Possible connection leak

[Tatsuo Ishii]

That's no problem. Because the old one ("Connected" = 0) can accept
new connection. As long as there are process which have ("Connected" =
0), pgpool-II happily accepts new connections.

You can verify it by setting num_init_children = 2 and do:

psql db1
\c db2
\c db1
\c db2
:
:

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp

> The old one has a value of 0. But remains in the list until the child life time is reached.
> 
> Kind regards,
> Derek.
> 
>> On 18 Aug 2015, at 12:46 pm, Tatsuo Ishii <ishii at postgresql.org> wrote:
>> 
>> Does not reporduce here. Are sure that "Connected" field is 1 for both
>> the new and old database?
>> 
>> Database     : test2
>> Username     : t-ishii
>> Start time   : 2015-08-18 11:40:05
>> Creation time: 2015-08-18 11:44:17
>> Major        : 3
>> Minor        : 0
>> Counter      : 1
>> Backend PID  : 6564
>> Connected    : 1
>> PID          : 6534
>> Backend ID   : 0
>> 
>> Best regards,
>> --
>> Tatsuo Ishii
>> SRA OSS, Inc. Japan
>> English: http://www.sraoss.co.jp/index_en.php
>> Japanese:http://www.sraoss.co.jp
>> 
>>> Hi,
>>> 
>>> Psql to pgpool. 
>>> 
>>> After logging into the Postgres database, then switch to another database, it would have 2 processes according to pcp_proc_info. 
>>> 
>>> 
>>> Kind regards,
>>> Derek.
>>> 
>>> On 18 Aug 2015, at 11:59 am, Tatsuo Ishii <ishii at postgresql.org> wrote:
>>> 
>>>>> Hi,
>>>>> 
>>>>> I'm current running pgpool-II 3.4.3-1 using pgpoolAdmin 3.4.1 on Rhel7.1.
>>>>> 
>>>>> When I connect using psql to database1 via the virtual ip, then later switch over to another database2 using the "\c". Then switch back to database1. Pgpool creates 3 connections, which I can see in pgpoolAdmin->status->processes.
>>>>> 
>>>>> If I continue to switch between the two databases, it will continue to increase the number of pgpool connections via the virtual ip. Eventually, these connections timeout when it reaches the child_life_time value or if it reaches the num_init_children limit, it will hang until a connection is available.
>>>> 
>>>> I don't know when you say "the number of pgpool connections", these
>>>> are from client (psql) to pgpool or pgpool to PostgreSQL. Because the
>>>> former will not increase as long as the number of psql you are using,
>>>> I assume you are referring to connections from pgpool to
>>>> PostgreSQL.
>>>> 
>>>> The number could increase until num_init_children reaches. However
>>>> some of process are expected to accept connections from clients. You
>>>> could verify it by using "show pool_nodes". "pool_connected" column
>>>> indicates that the process is ready to accept connections from clients
>>>> (in this case 0).
>>>> 
>>>> Please remeber, however, that psql keeps old connection until \c
>>>> succeeds. For example, if num_init_children = 1, you are never able to
>>>> use \c.
>>>> 
>>>>> I have the connection_cache on.
>>>>> 
>>>>> Is there something that I need to set?
>>>> 
>>>> You might want to set client_idle_limit.
>>>> 
>>>> Best regards,
>>>> --
>>>> Tatsuo Ishii
>>>> SRA OSS, Inc. Japan
>>>> English: http://www.sraoss.co.jp/index_en.php
>>>> Japanese:http://www.sraoss.co.jp