FD_SETSIZE is included in sys/select.h per POSIX, and this header
inclusion has been moved to scripts_parallel.c as of 5f38403 without
moving the variable, causing a compilation failure on recent versions of
OpenBSD (6.6 was the version used in the report).
In order to take care of the failure, move FD_SETSIZE directly to
scripts_parallel.c with a wrapper controlling the maximum number of
parallel slots supported, based on a suggestion by Andres Freund.
While on it, reduce the maximum number to be less than FD_SETSIZE,
leaving some room for stdin, stdout and such as they consume some file
descriptors.
The buildfarm did not complain about that, as it happens to only be
an issue on recent versions of OpenBSD and there is no coverage in this
area. 51c3e9f fixed a similar set of issues.
Bug: #15964
Reported-by: Sean Farrell
Discussion: https://postgr.es/m/15964-c1753bdfed722e04@postgresql.org
The existing facility of vacuumdb to handle parallel connections into a
given database with an authentication set is moved to a common file in
src/bin/scripts/, named scripts_parallel.c. This introduces a set of
routines to initialize, wait and terminate a set of connections,
simplifying a bit the code of vacuumdb on the way. More routines
related to result handling and database connection are moved to
common.c.
The initial plan is to use that for reindexdb, but it could be applied
to other tools like clusterdb.
While on it, clean up a set of variables "progname" which were defined
as routine arguments for error messages. Since most of the callers have
switched to pg_log_error() and such there is no need for this variable.
Author: Julien Rouhaud
Reviewed-by: Michael Paquier, Álvaro Herrera
Discussion: https://postgr.es/m/CAOBaU_YrnH_Jqo46NhaJ7uRBiWWEcS40VNRQxgFbqYo9kApUsg@mail.gmail.com
