Re: Listen / Notify - what to do when the queue is full

On Tue, 2010-01-19 at 19:24 -0500, Tom Lane wrote:
> Jeff Davis <pgsql@j-davis.com> writes:
> > I was also worried about holding multiple LWLocks at once -- is such
> > practice generally avoided in the rest of the code?
> 
> It's allowed but remember that there is no deadlock detection in lwlock.c.
> You must be very certain that there is only one possible order in which
> such locks could be taken.  Interactions with heavyweight locks would be
> bad news as well.

That was my worry initially.

> On the whole it might be better if a heavyweight lock were used,
> such that it'll automatically clean up after commit.  (I'm still
> wondering if we couldn't do without the lock altogether though.)

Yes, I think there's a better way as well. I'll look into it.

Regards,
	Jeff Davis