Re: pg_basebackup behavior on non-existent slot

Magnus Hagander wrote:
> On Mon, Sep 4, 2017 at 3:21 PM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:

> > Should the parent process of pg_basebackup be made to respond to SIGCHLD?
> > Or call waitpid(bgchild, &status, WNOHANG) in some strategic loop?
>
> I think it's ok to just call waitpid() -- we don't need to react super
> quickly, but we should react.

Hmm, not sure about that ... in the normal case (slotname is correct)
you'd be doing thousands of useless waitpid() system calls during the
whole operation, no? I think it'd be better to have a SIGCHLD handler
that sets a flag (just once), which can be quickly checked without
accessing kernel space.

> And we should then exit the main process with an error before actually
> streaming everything.

Right.

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Álvaro Herrera https://www.2ndQuadrant.com/
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