| From: | Jeff Davis <pgsql(at)j-davis(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Joachim Wieland <joe(at)mcknight(dot)de>, Greg Smith <greg(at)2ndquadrant(dot)com>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, "Florian G(dot) Pflug" <fgp(at)phlo(dot)org>, Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Listen / Notify - what to do when the queue is full |
| Date: | 2010-01-20 00:29:03 |
| Message-ID: | 1263947343.13109.35.camel@monkey-cat.sm.truviso.com |
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| Lists: | pgsql-hackers |
On Tue, 2010-01-19 at 19:24 -0500, Tom Lane wrote:
> Jeff Davis <pgsql(at)j-davis(dot)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
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