Re: LISTEN / NOTIFY performance in 8.3

From: James Mansion <james(at)mansionfamily(dot)plus(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Joel Stevenson <joelstevenson(at)mac(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: LISTEN / NOTIFY performance in 8.3
Date: 2008-02-26 22:15:58
Message-ID: 47C48F9E.7000505@mansionfamily.plus.com
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Tom Lane wrote:
> read-modify-write type of operation it uses an exclusive lock, so only
> one can clear its pg_listener entry at a time. The 'waiting' ones you
> are seeing are stacked up behind whichever one has the lock at the
> moment. They shouldn't be waiting for long.
>
I certainly hadn't expected that to be the implementation technique -
isn't it smply that we need
a sngle flag per worker process and can set/test-and-clear with atomic
operations and then a
signal to wake them up?

Anyway - how hard would it be to install triggers on commit and
rollback? Then we could write
our own mechanisms.

James

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