Re: Rename max_parallel_degree?

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>

To: Robert Haas <robertmhaas@gmail.com>

Cc: Julien Rouhaud <julien.rouhaud@dalibo.com>, Josh Berkus <josh@agliodbs.com>, "David G. Johnston" <david.g.johnston@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, Peter Geoghegan <pg@heroku.com>, Noah Misch <noah@leadboat.com>, David Rowley <david.rowley@2ndquadrant.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, Magnus Hagander <magnus@hagander.net>, Bruce Momjian <bruce@momjian.us>, PostgreSQL-development <pgsql-hackers@postgresql.org>

Date: 2016-06-14T16:16:16Z

Lists: pgsql-hackers

Robert Haas <robertmhaas@gmail.com> writes:
> Of course, it would be nice if we could make these counters 64-bit
> integers, but we can't, because we don't rely on 64-bit reads and
> writes to be atomic on all platforms.  So instead they'll have to be
> uint32.  That means they could wrap (if you really work at it) but
> subtraction will still return the right answer, so it's OK.

OK ...

> If we
> want to allow the number of parallel workers started to be available
> for statistical purposes, we can keep to uint32 values for that
> (parallel_register_count_lo and parallel_register_count_hi, for
> example), and increment the second one whenever the first one rolls
> over to zero.

And that's going to be atomic how exactly?

			regards, tom lane