Re: please update ps display for recovery checkpoint

On Wed, Dec 09, 2020 at 02:00:44AM +0900, Fujii Masao wrote:
> I agree it might be helpful to display something like
> "checkpointing" or "waiting for checkpoint" in PS title for the
> startup process.

Thanks.

> But, at least for me, it seems strange to display "idle" only for
> checkpointer.

Yeah, I'd rather leave out the part of the patch where we have the
checkpointer say "idle".  So I still think that what v3 did upthread,
by just resetting the ps display in all cases, feels more natural.  So
we should remove the parts of v5 from checkpointer.c.

+        * Reset the ps status display.  We set the status to "idle" for the
+        * checkpointer process, and we clear it for anything else that runs this
+        * code.
+        */
+       if (MyBackendType == B_CHECKPOINTER)
+               set_ps_display("idle");
+       else
+               set_ps_display("");
Regarding this part, this just needs a reset with an empty string.
The second sentence is confusing (it partially comes fronm v3, from
me..).  Do we lose anything by removing the second sentence of this
comment?

+   snprintf(activitymsg, sizeof(activitymsg), "creating %s%scheckpoint",
[...]
+   snprintf(activitymsg, sizeof(activitymsg), "creating %srestartpoint",
FWIW, I still fing "running" to sound better than "creating" here.  An
extra term I can think of that could be adapted is "performing".

> *If* we want to monitor the current status of
> checkpointer, it should be shown as wait event in pg_stat_activity,
> instead? 

That would be WAIT_EVENT_CHECKPOINTER_MAIN, now there has been also on
this thread an argument that you would not have access to
pg_stat_activity until crash recovery completes and consistency is
restored.
--
Michael