Re: A new function to wait for the backend exit after termination

On Tue, Jun 01, 2021 at 01:25:24PM +0530, Bharath Rupireddy wrote:
> On Tue, Jun 1, 2021 at 9:19 AM Noah Misch <noah@leadboat.com> wrote:
> > Given that limitation, is pg_wait_for_backend_termination() useful enough?  If
> > waiting for procarray departure is enough, should pg_wait_until_termination()
> > check BackendPidGetProc(pid) instead of kill(0, pid), so it can return
> > earlier?
> 
> We can just remove BackendPidGetProc(pid) in
> pg_wait_for_backend_termination. With this change, we can get rid of
> the wait_pid() from regress.c. But, my concern is that the
> pg_wait_for_backend_termination() can also check non-postgres server
> process pid. Is this okay?

It may or may not be okay.  I would not feel good about it.

> In that case, this function becomes a
> generic(OS level function) rather than a postgres server specific
> function. I'm not sure if all agree to that. Thoughts?

My preference is to remove pg_wait_for_backend_termination().  The use case
that prompted this thread used pg_terminate_backend(pid, 180000); it doesn't
need pg_wait_for_backend_termination().