[pgpool-hackers: 2284] Re: RFC: New health check implementation

[Muhammad Usama]

Hi Ishii-San

I am working on config framework modification to allow same name parameters
with and without index postfix, I am almost done with the framework related
changes.
And now for testing I need to add one such parameter and I was thinking
instead of using a dummy configuration variable for testing I would rather
add the *health_check_period* and *health_check_period[idx]* so that you
can also use it.
For that can you tell me where do you want to create health_check_period
variable for each backend? Is BackendInfo structure is the right place?

Thanks
Best Regards


On Mon, Apr 24, 2017 at 7:42 AM, Tatsuo Ishii <ishii at sraoss.co.jp> wrote:

> >> On 21-Apr-2017, at 4:31 AM, Tatsuo Ishii <ishii at sraoss.co.jp> wrote:
> >>
> >> Usama,
> >>
> >> Is it possible to have following config parameter at the same time?
> >> My feeling is we can't because current implementation of config
> >> handling does not allow it.
> >>
> >> health_check_period = 10
> >> health_check_period0 = 5
> >
> > Yes, having the same named configuration parameter with and without
> index postfix would cause problem with the current implementations, but if
> we want to support this I can tweak the configuration framework to allow
> that.
>
> That would be desirable.
>
> Best regards,
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese:http://www.sraoss.co.jp
>
> > Thanks
> > Best regards
> > Muhammad Usama
> >
> >>
> >> Best regards,
> >> --
> >> Tatsuo Ishii
> >> SRA OSS, Inc. Japan
> >> English: http://www.sraoss.co.jp/index_en.php
> >> Japanese:http://www.sraoss.co.jp
> >>
> >>> Hi,
> >>>
> >>> This is a Request for Comments on the new implementation of health
> >>> check aiming for Pgpool-II 3.7.
> >>>
> >>> Problems:
> >>>
> >>> Current implementation of health check is a single serial processing
> >>> for all of database nodes. This implies some limitations for health
> >>> check process: 1) it is not possible to specify different health check
> >>> configuration values for each database node, 2) node failure detection
> >>> may take longer. For example, if it takes 10 seconds before detecting
> >>> node 0 failure, then detecting node 1 failure will be delayed at least
> >>> 10 seconds because it starts node failure detection after node 0.
> >>>
> >>> The solution:
> >>>
> >>> Allow to specify health check parameters for each node. Pgpool.conf
> >>> will look like:
> >>>
> >>> health_check_period0 = 10
> >>> health_check_timeout0 = 20
> >>> :
> >>> :
> >>>
> >>> where "0" means database node 0 (similar concept as "backend_*0
> >>> parameters).
> >>>
> >>> To make admin's life easier, current parameters can be used as
> >>> well. Suppose there are 3 nodes, and we have:
> >>>
> >>> health_check_period = 10
> >>> health_check_period0 = 5
> >>>
> >>> then health_check_period for node 1 and 2 will be 10, while
> >>> health_check_period for node 0 will be 5. So parameter names without
> >>> node id works as a "global variable".
> >>>
> >>> The implementation:
> >>>
> >>> Create separate child process of pgpool main process and let do the
> >>> heal check job for each database node. Once the health check child
> >>> process detects node failure, it signals to main process and main
> >>> process will perform failover.
> >>>
> >>> This architecture makes pgpool main process simpler and robust, while
> >>> earlier detection of node failure by the health check child process.
> >>>
> >>> Comments and suggestions are welcome.
> >>>
> >>> Best regards,
> >>> --
> >>> Tatsuo Ishii
> >>> SRA OSS, Inc. Japan
> >>> English: http://www.sraoss.co.jp/index_en.php
> >>> Japanese:http://www.sraoss.co.jp
> >>> _______________________________________________
> >>> pgpool-hackers mailing list
> >>> pgpool-hackers at pgpool.net
> >>> http://www.pgpool.net/mailman/listinfo/pgpool-hackers
>
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