[pgpool-general: 8009] Re: connection is not available

[Nikolay Mastilo (HM)]

Hello
>> Hello,
>>
>> There are no additional errors on pgpool when that exceptions appears.
>>
>> We tested by Jmeter tool.
>>
>> It was configured for send read requests to service that connected to
>> pgpool.
>>
>> The requests was sent as 300 Threads within 100 second Ramp-up period
>> (time that takes to start all the threads))
>>
>> I don’t think it makes sense to tell which requests in detail, since
>> they are specific to our service.
>>
>> Because not all child processes of Pgpool was busy during load
>> testing. We set 200 child processes and 30% of the processes was free.
> How do you define child processes of Pgpool was busy or free?
[NM]: I make connection to database via Pgpool in this time and it 
response normally.
>
> If a child processes of Pgpool is occupied by a client session, then
> other client cannot connect to the child process of Pgpool until the
> client disconnects to the process. It's not irrevelant whether the
> process is actually doing something or not.
>
> If you are using the latest Pgpool-II version (4.3.x), pcp_proc_info
> command can tell you whether each child process is occupied by client
> session. If it's other than "wait for connection request" then it's
> occupied. See the manual for details.
>
> If you are using pre 4.3, you can use ps command to the each process
> status.
>
>> It looks like Pgpool sometimes doesn't keep up to serve new connection
>> request for some reason. Is it possible? What are the likely reasons
>> for this?
> I guess you have to increase num_init_children to more than 300 since
> your test generates 300 connections.

[NM]: We will need establish 3000+ connections in our perspective.

Can we increase num_init_children until 3000?

How much computing resources of the CPU and RAM may be needed in this case?

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

Regards,
Nikolay

>> Regards,
>> Nikolay
>>
>> On 25.01.2022 06:11, Bo Peng wrote:
>>> Hello,
>>>
>>> On Mon, 24 Jan 2022 18:22:12 +0200
>>> "Nikolay Mastilo (HM)" <nikm71 at hotmail.com> wrote:
>>>
>>>> Hello,
>>>>
>>>> In our environment we received the error of our service that connects
>>>> to Pgpool:
>>>>
>>>> "HikariPool-1 - Connection is not available, request timed out after
>>>> 30012ms."
>>>>
>>>> We run load test that generate 300 connections that send requests to
>>>> database each 1-4 sec via Pgpool.
>>>>
>>>> Most of connections was successed. But 3-4% was failed and service
>>>> produced exception log which I mentioned above.
>>>>
>>>> num_init_children = 200
>>>>
>>>> max_pool = 4
>>>>
>>>> I will be appreciate any idea what's going on.
>>> Thank you for reporting this issue.
>>>
>>> Is there any error in pgpool logs?
>>>
>>> It would be appreciated if you could share the load test scenario
>>> to help us to reproduce this issue.
>>>
>>>
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