On 2014-02-14 10:26:07 -0500, Tom Lane wrote: > Florian Pflug <f...@phlo.org> writes: > > Another idea for a fix would be to conflate lwWaiting and lwWaitLink into > > one > > field. We could replace "lwWaiting" by "lwWaitLink != NULL" everywhere it's > > tested, and set lwWaitLink to some special non-NULL value (say 0x1) when we > > enqueue a PGPROC, instead of setting it to NULL and setting lwWaiting to > > true. > > > We'd then depend on pointer-sized stores being atomic, which I think we > > depend > > on in other places already. > > I don't believe that's true; neither that we depend on it now, nor that > it would be safe to do so.
Yea, we currently rely on 4 byte stores being atomic (most notably for xids), but we don't rely on anything bigger. I am not sure if there are architectures with 64bit pointers that aren't accessed atomically when aligned? Even if, that's certainly nothing that should be introduced when backpatching. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
