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From: Nathan Bossart <nathandbossart@gmail.com>
To: Sami Imseih <samimseih@gmail.com>
Cc: Rahila Syed <rahilasyed90@gmail.com>
Cc: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andres Freund <andres@anarazel.de>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: Improve LWLock tranche name visibility across backends
Date: Thu, 4 Sep 2025 15:37:51 -0500
Message-ID: <aLn4n-5UFzKHFdR5@nathan> (raw)
In-Reply-To: <CAA5RZ0t6s2Z38oRq883Ocq7J4xjn1FJF17Q4YR6++vrw5KYCtQ@mail.gmail.com>
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On Thu, Sep 04, 2025 at 12:30:27PM -0500, Sami Imseih wrote:
> I liked removing the repalloc calls inside this routine and did not think
> it was worth optimizing. I am OK with reverting it back. Although v1
> is incorrect since it's still initializing
> NamedLWLockTrancheRequestArray to MAX_NAMED_TRANCHES

Committed with that fix.

>> Furthermore, the
>> MAX_NAMED_TRANCHES check isn't actually needed because InitializeLWLocks()
>> will do the same check via its calls to LWLockNewTrancheId() for all the
>> named tranche requests.
> 
> I thought about that one and decided to add the error message there, since
> requesting a tranche happens way before LWLockNewTrancheId is called
> during CreateLWLocks, so it was more about erroring out slightly earlier.
> But it may be ok to also just remove it.

We needed it before because the array could only ever hold
MAX_NAMED_TRANCHES requests.

-- 
nathan





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  Subject: Re: Improve LWLock tranche name visibility across backends
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