Re: Proposal : For Auto-Prewarm.

Hello,

On Wed, Feb 8, 2017 at 3:40 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:

> On Tue, Feb 7, 2017 at 5:14 PM, Mithun Cy <mithun(dot)cy(at)enterprisedb(dot)com>
> wrote:
> > On Tue, Feb 7, 2017 at 12:24 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
> wrote:
> >> On Tue, Feb 7, 2017 at 11:53 AM, Beena Emerson <memissemerson(at)gmail(dot)com>
> wrote:
> >>> Are 2 workers required?
> >>>
> >>
> >> I think in the new design there is a provision of launching the worker
> >> dynamically to dump the buffers, so there seems to be a need of
> >> separate workers for loading and dumping the buffers. However, there
> >> is no explanation in the patch or otherwise when and why this needs a
> >> pair of workers. Also, if the dump interval is greater than zero,
> >> then do we really need to separately register a dynamic worker?
> >
> > We have introduced a new value -1 for pg_prewarm.dump_interval this
> > means we will not dump at all, At this state, I thought auto
> > pg_prewarm process need not run at all, so I coded to exit the auto
> > pg_prewarm immediately. But If the user decides to start the auto
> > pg_prewarm to dump only without restarting the server, I have
> > introduced a launcher function "launch_pg_prewarm_dump" to restart the
> > auto pg_prewarm only to dump. Since now we can launch worker only to
> > dump, I thought we can redistribute the code between two workers, one
> > which only does prewarm (load only) and another dumps periodically.
> > This helped me to modularize and reuse the code. So once load worker
> > has finished its job, it registers a dump worker and then exists.
> > But if max_worker_processes is not enough to launch the "auto
> > pg_prewarm dump" bgworker
> > We throw an error
> > 2017-02-07 14:51:59.789 IST [50481] ERROR: registering dynamic
> > bgworker "auto pg_prewarm dump" failed c
> > 2017-02-07 14:51:59.789 IST [50481] HINT: Consider increasing
> > configuration parameter "max_worker_processes".
> >
> > Now thinking again instead of such error and then correcting same by
> > explicitly launching the auto pg_prewarm dump bgwroker through
> > launch_pg_prewarm_dump(), I can go back to original design where there
> > will be one worker which loads and then dumps periodically. And
> > launch_pg_prewarm_dump will relaunch dump only activity of that
> > worker. Does this sound good?
> >
>
> Won't it be simple if you consider -1 as a value to just load library?
> For *_interval = -1, it will neither load nor dump.
>
>
+1
That is what I thought was the behaviour we decided upon for -1.

--
Thank you,

Beena Emerson

Have a Great Day!