Re: Re: [COMMITTERS] pgsql: Introduce group locking to prevent parallel processes from deadl

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> Hmm, that's true. I don't think it actually matters all that much,
> because proclock->tag.myProc->lockGroupLeader == NULL has pretty much
> the same effect as if proclock->tag.myProc->lockGroupLeader ==
> proclock->tag.myProc. But not completely. One problem is that we
> don't currently assume that 8-byte writes are atomic, so somebody
> might see the group leader field half-set, which would be bad.

Yes, exactly. I'm not certain if there are any real platforms where
a pointer-sized write wouldn't be atomic (it sure sounds inefficient
for that to be true), but we have not assumed that to date and I'd
just as soon not start here.

regards, tom lane