Re: Restart pg_usleep when interrupted

> From this discussion, there is desire for a sleep function that:
> 1/ Sleeps for the full duration of the requested time
> 2/ Continues to handle important interrupts during the sleep
>
> While something like CF 5118 will take care of point #1,

> I'm not sure, even with CF entry 5118, nanosleep() could be interrupted. But I
> agree that the leader won't be interrupted by PqMsg_Progress anymore.

Correct.

> 1. we should still implement the "1 Hz" stuff as 1.1/ it could be useful if CF
> 5118 gets committed and we move to WaitLatchUs() and 2.2/ it won't break anything
> if CF gets committed and we don't move to WaitLatchUs(). For 1.1 it would still
> prevent the leader to be waked up too frequently by the parallel workers.

Yes, regardless of any changes that may occur in the future that change the behaior
of pg_usleep, preventing a leader from being woken up too frequently is
good to have. The "1 Hz" work is still good to have.

> 2. still discuss the "need" and get a consensus regarding a sleep that could
> ensure the wait duration (in some cases and depending of the reason why the
> process is waked up).

Unless there is objection, I will withdraw the CF [1] entry for this patch next week.

This discussion however should be one of the points that CF 5118 must deal with.
That is, 5118 will change the behavior of pg_usleep when dealing with interrupts
previously signaled by SIGUSR1.

[1] https://commitfest.postgresql.org/49/5161/

Regards,

Sami