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* Re: Can a long running procedure detect when smart shutdown is pending?
@ 2024-07-06 06:22 Pavel Stehule <[email protected]>
2024-07-06 08:09 ` Re: Can a long running procedure detect when smart shutdown is pending? Achilleas Mantzios <[email protected]>
0 siblings, 1 reply; 2+ messages in thread
From: Pavel Stehule @ 2024-07-06 06:22 UTC (permalink / raw)
To: Achilleas Mantzios <[email protected]>; +Cc: [email protected]; [email protected]
so 6. 7. 2024 v 8:19 odesílatel Pavel Stehule <[email protected]>
napsal:
>
>
> so 6. 7. 2024 v 8:06 odesílatel Achilleas Mantzios <
> [email protected]> napsal:
>
>> Στις 6/7/24 08:39, ο/η Pavel Stehule έγραψε:
>>
>>
>>
>> so 6. 7. 2024 v 1:36 odesílatel Dennis White <[email protected]>
>> napsal:
>>
>>> Thanks for responding.
>>> This will be a stored procedure written in plpgsql that's kicked off by
>>> pg_cron.
>>> I wasn't sure a normal smart shutdown would stop it.
>>>
>>
>> shutdown try to cancel any query. The plpgsql routine should be canceled
>> without problems.
>>
>> fast mode will have this effect. smart mode not, from my testing. The
>> running queries do not get interrupted in smart shutdown.
>>
>
> ok
>
> but you can set timeout there. It doesn't help?
>
> You can create some aux postgresql connection with specific app name, and
> then you can monitor if this process still live from pg_stat_activity
>
> one process
>
> connect
> set application_name to 'xxxx';
>
> second process
> if not exists(select * from pg_stat_activity where appname = 'xxxx') then
> exit
> end if;
>
>
sorry - it cannot to help too
probably only one solution can be to write some extension and read some
internal state
>
>
>
>>
>>
>>
>>>
>>> Thanks
>>>
>>> On Fri, Jul 5, 2024 at 4:57 PM Achilleas Mantzios <
>>> [email protected]> wrote:
>>>
>>>> Στις 5/7/24 21:12, ο/η Dennis White έγραψε:
>>>>
>>>> My project's DB has a mutli-step stored procedure using Transaction
>>>> Control that may take 30 minutes or more to complete.
>>>> I am curious if there is a way to make it more smart shutdown friendly
>>>> so it can stop between steps?
>>>>
>>>> We are using both PG 14 and PG 16 on Rhel 8.
>>>> Pardon me if it's obvious but is there a function to call or a table
>>>> that could be checked after a commit within the procedure to determine a
>>>> shutdown is pending?
>>>>
>>>> Maybe somehow checking the log for a message like :
>>>>
>>>> received smart shutdown request
>>>>
>>>> Or use tail_n_mail against the log and then implement some logic using
>>>> NOTIFY , ideally you want your procedure to be interrupted rather than do
>>>> polling.
>>>>
>>>>
>>>> Thanks,
>>>> Dennis
>>>>
>>>> --
>>>> Achilleas Mantzios
>>>> IT DEV - HEAD
>>>> IT DEPT
>>>> Dynacom Tankers Mgmt (as agents only)
>>>>
>>>> --
>> Achilleas Mantzios
>> IT DEV - HEAD
>> IT DEPT
>> Dynacom Tankers Mgmt (as agents only)
>>
>>
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: Can a long running procedure detect when smart shutdown is pending?
2024-07-06 06:22 Re: Can a long running procedure detect when smart shutdown is pending? Pavel Stehule <[email protected]>
@ 2024-07-06 08:09 ` Achilleas Mantzios <[email protected]>
0 siblings, 0 replies; 2+ messages in thread
From: Achilleas Mantzios @ 2024-07-06 08:09 UTC (permalink / raw)
To: Pavel Stehule <[email protected]>; +Cc: [email protected]; [email protected]
Στις 6/7/24 09:22, ο/η Pavel Stehule έγραψε:
>
>
> so 6. 7. 2024 v 8:19 odesílatel Pavel Stehule
> <[email protected]> napsal:
>
>
>
> so 6. 7. 2024 v 8:06 odesílatel Achilleas Mantzios
> <[email protected]> napsal:
>
> Στις 6/7/24 08:39, ο/η Pavel Stehule έγραψε:
>>
>>
>> so 6. 7. 2024 v 1:36 odesílatel Dennis White
>> <[email protected]> napsal:
>>
>> Thanks for responding.
>> This will be a stored procedure written in plpgsql that's
>> kicked off by pg_cron.
>> I wasn't sure a normal smart shutdown would stop it.
>>
>>
>> shutdown try to cancel any query. The plpgsql routine should
>> be canceled without problems.
> fast mode will have this effect. smart mode not, from my
> testing. The running queries do not get interrupted in smart
> shutdown.
>
>
> ok
>
> but you can set timeout there. It doesn't help?
>
> You can create some aux postgresql connection with specific app
> name, and then you can monitor if this process still live from
> pg_stat_activity
>
> one process
>
> connect
> set application_name to 'xxxx';
>
> second process
> if not exists(select * from pg_stat_activity where appname =
> 'xxxx') then
> exit
> end if;
>
>
> sorry - it cannot to help too
>
> probably only one solution can be to write some extension and read
> some internal state
One idea was to have a process reading the log for " received smart
shutdown request " and then send a
NOTIFY shutdown_channel, 'shutdown in progress'
The question I have not yet answered is how to get the asynchronous
notification from within plpgsql. I mean this is possible with python or
Go or Java / JDBC or some other programming language , but cannot seem
to find anything in plpgsql .
>
>
>>
>>
>>
>> Thanks
>>
>> On Fri, Jul 5, 2024 at 4:57 PM Achilleas Mantzios
>> <[email protected]> wrote:
>>
>> Στις 5/7/24 21:12, ο/η Dennis White έγραψε:
>>> My project's DB has a mutli-step stored procedure
>>> using Transaction Control that may take 30 minutes
>>> or more to complete.
>>> I am curious if there is a way to make it more smart
>>> shutdown friendly so it can stop between steps?
>>>
>>> We are using both PG 14 and PG 16 on Rhel 8.
>>> Pardon me if it's obvious but is there a function to
>>> call or a table that could be checked after a commit
>>> within the procedure to determine a shutdown is pending?
>>
>> Maybe somehow checking the log for a message like :
>>
>> received smart shutdown request
>>
>> Or use tail_n_mail against the log and then implement
>> some logic using NOTIFY , ideally you want your
>> procedure to be interrupted rather than do polling.
>>
>>>
>>> Thanks,
>>> Dennis
>>
>> --
>> Achilleas Mantzios
>> IT DEV - HEAD
>> IT DEPT
>> Dynacom Tankers Mgmt (as agents only)
>>
> --
> Achilleas Mantzios
> IT DEV - HEAD
> IT DEPT
> Dynacom Tankers Mgmt (as agents only)
>
--
Achilleas Mantzios
IT DEV - HEAD
IT DEPT
Dynacom Tankers Mgmt (as agents only)
^ permalink raw reply [nested|flat] 2+ messages in thread
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2024-07-06 06:22 Re: Can a long running procedure detect when smart shutdown is pending? Pavel Stehule <[email protected]>
2024-07-06 08:09 ` Achilleas Mantzios <[email protected]>
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