Re: Sync Rep v19

On Sun, 2011-03-06 at 14:27 +0900, Fujii Masao wrote:
> On Sun, Mar 6, 2011 at 2:59 AM, Robert Haas <robertmhaas@gmail.com> wrote:
> > On Sat, Mar 5, 2011 at 11:56 AM, Simon Riggs <simon@2ndquadrant.com> wrote:
> >>> Even though postmaster dies, the waiting backend keeps waiting until
> >>> the timeout expires. Instead, the backends should periodically check
> >>> whether postmaster is alive, and then they should exit immediately
> >>> if it's not alive, as well as other process does? If the timeout is
> >>> disabled, such backends would get stuck infinitely.
> >>
> >> Will wake them every 60 seconds
> >
> > I don't really see why sync rep should be responsible for solving this
> > problem, which is an issue in many other situations as well, only for
> > itself. In fact I think I'd prefer that it didn't, and that we wait
> > for a more general solution that will actually fix this problem for
> > real.
> 
> I agree if such a general solution will be committed together with sync rep.
> Otherwise, because of sync rep, the backend can easily get stuck *infinitely*.
> When postmaster is not alive, all the existing walsenders exit immediately
> and no new walsender can appear. So there is no way to release the
> waiting backend. I think that some solutions for this issue which is likely to
> happen are required.

Completely agree.

-- Simon Riggs           http://www.2ndQuadrant.com/books/PostgreSQL Development, 24x7 Support, Training and Services