Re: Trap errors from streaming child in pg_basebackup to exit early

> On 28 Sep 2021, at 15:48, Magnus Hagander <magnus(at)hagander(dot)net> wrote:

> Might be worth noting in one of the comments the difference in
> behaviour if the backend process/thread *crashes* -- that is, on Unix
> it will be detected via the signal handler and on Windows the whole
> process including the main thread will die, so there is nothing to
> detect.

Good point, done.

> Other places in the code just refers to the background process as "the
> background process". The term "WAL receiver" is new from this patch.
> While I agree it's in many ways a better term, I think (1) we should
> try to be consistent, and (2) maybe use a different term than "WAL
> receiver" specifically because we have a backend component with that
> name.

Looking at the user-facing messaging we have before this patch, there is a bit
of variability:

On UNIX:

pg_log_error("could not create pipe for background process: %m");
pg_log_error("could not create background process: %m");
pg_log_info("could not send command to background pipe: %m");
pg_log_error("could not wait for child process: %m");

On Windows:

pg_log_error("could not create background thread: %m");
pg_log_error("could not get child thread exit status: %m");
pg_log_error("could not wait for child thread: %m");
pg_log_error("child thread exited with error %u", ..);

On Both:

pg_log_info("starting background WAL receiver");
pg_log_info("waiting for background process to finish streaming ...");

So there is one mention of a background WAL receiver already in there, but it's
pretty inconsistent as to what we call it. For now I've changed the messaging
in this patch to say "background process", leaving making this all consistent
for a follow-up patch.

The attached fixes the above, as well as the typo mentioned off-list and is
rebased on top of todays HEAD.

--
Daniel Gustafsson https://vmware.com/