Re: Is Recovery actually paused?

Hi,

On Sun, 7 Feb 2021 19:27:02 +0530
Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:

> On Sun, Feb 7, 2021 at 6:44 PM Bharath Rupireddy
> <bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
> >
> > On Fri, Feb 5, 2021 at 10:14 AM Bharath Rupireddy
> > <bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
> > > > We can not do that, basically, under one lock we need to check the
> > > > state and set it to pause. Because by the time you release the lock
> > > > someone might set it to RECOVERY_NOT_PAUSED then you don't want to set
> > > > it to RECOVERY_PAUSED.
> > >
> > > Got it. Thanks.
> >
> > Hi Dilip, I have one more question:
> >
> > + /* test for recovery pause, if user has requested the pause */
> > + if (((volatile XLogCtlData *) XLogCtl)->recoveryPauseState ==
> > + RECOVERY_PAUSE_REQUESTED)
> > + recoveryPausesHere(false);
> > +
> > + now = GetCurrentTimestamp();
> > +
> >
> > Do we need now = GetCurrentTimestamp(); here? Because, I see that
> > whenever the variable now is used within the for loop in
> > WaitForWALToBecomeAvailable, it's re-calculated anyways. It's being
> > used within case XLOG_FROM_STREAM:
> >
> > Am I missing something?
>
> Yeah, I don't see any reason for doing this, maybe it got copy pasted
> by mistake. Thanks for observing this.

I also have a question:

@@ -6270,14 +6291,14 @@ RecoveryRequiresIntParameter(const char *param_name, int currValue, int minValue
currValue,
minValue)));

- SetRecoveryPause(true);
+ SetRecoveryPause(RECOVERY_PAUSED);

ereport(LOG,
(errmsg("recovery has paused"),
errdetail("If recovery is unpaused, the server will shut down."),
errhint("You can then restart the server after making the necessary configuration changes.")));

- while (RecoveryIsPaused())
+ while (GetRecoveryPauseState() != RECOVERY_NOT_PAUSED)
{
HandleStartupProcInterrupts();

If a user call pg_wal_replay_pause while waiting in RecoveryRequiresIntParameter,
the state become 'pause requested' and this never returns to 'paused'.
Should we check recoveryPauseState in this loop as in recoveryPausesHere?

Regards,
Yugo Nagata

--
Yugo NAGATA <nagata(at)sraoss(dot)co(dot)jp>