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Date: Tue, 26 Feb 2008 22:15:58 +0000
From: James Mansion <james@mansionfamily.plus.com>
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To: Tom Lane <tgl@sss.pgh.pa.us>
CC: Joel Stevenson <joelstevenson@mac.com>, pgsql-performance@postgresql.org
Subject: Re: LISTEN / NOTIFY performance in 8.3
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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