Re: Sync Rep v17

Robert Haas <robertmhaas@gmail.com> writes:
> On Tue, Mar 1, 2011 at 3:21 AM, Simon Riggs <simon@2ndquadrant.com> wrote:
>> LWlocks are just spinlocks plus sem sleeps, so I don't see the need for
>> that in the current code. Other views welcome.

> An LWLock is a lot safer, in general, than a spinlock.  A spinlock
> mustn't do anything that could emit an error or abort (among other
> things).  I doubt that the performance cost of using an LWLock rather
> than a spin lock here is enough to matter, and the spin lock seems
> more likely to result in hard-to-find bugs.

Well, stuck spinlocks aren't exactly hard to identify.  But I agree that
the lack of any release-on-error infrastructure is a killer reason not
to use a spinlock for anything but short straight-line code segments.
        regards, tom lane