Re: Proposal: Out-of-Order NOTIFY via GUC to Improve LISTEN/NOTIFY Throughput - Mailing list pgsql-hackers

From Joel Jacobson
Subject Re: Proposal: Out-of-Order NOTIFY via GUC to Improve LISTEN/NOTIFY Throughput
Date
Msg-id 21f74513-85b0-4bd1-a6b6-09a6d3902e97@app.fastmail.com
Whole thread Raw
In response to Re: Proposal: Out-of-Order NOTIFY via GUC to Improve LISTEN/NOTIFY Throughput  ("Joel Jacobson" <joel@compiler.org>)
Responses Re: Proposal: Out-of-Order NOTIFY via GUC to Improve LISTEN/NOTIFY Throughput
List pgsql-hackers
On Fri, Jul 18, 2025, at 10:15, Joel Jacobson wrote:
> On Fri, Jul 18, 2025, at 02:49, Rishu Bagga wrote:
>> Hi all,
>>
>> There’s been some renewed attention on improving the performance of the
>> LISTEN/NOTIFY system, which historically hasn’t scaled well under high
>> notify frequency. Joel Jacobson recently shared some work on optimizing
>> the LISTEN path [1], and I wanted to follow up with a proposal focused on
>> the NOTIFY side.
>
> To clarify, my patch optimizes parallelizability of NOTIFY, without
> degrading parallelizability of LISTEN/UNLISTEN.

I realize my above clarification is not technically true,
what I meant to say is:

My patch improves NOTIFY TPS when many backends are listening on multiple
channels by eliminating unnecessary syscall wake‑ups, but it doesn't increase
the internal parallelism of the NOTIFY queue itself.

/Joel



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