Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1uqezu-00AfX5-9y for pgsql-hackers@arkaria.postgresql.org; Mon, 25 Aug 2025 21:45:03 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.94.2) (envelope-from ) id 1uqezt-00ElIv-Qd for pgsql-hackers@arkaria.postgresql.org; Mon, 25 Aug 2025 21:45:02 +0000 Received: from makus.postgresql.org ([2001:4800:3e1:1::229]) by malur.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1uqezt-00ElIj-HC for pgsql-hackers@lists.postgresql.org; Mon, 25 Aug 2025 21:45:02 +0000 Received: from mail-io1-xd30.google.com ([2607:f8b0:4864:20::d30]) by makus.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.96) (envelope-from ) id 1uqezq-001jMU-1L for pgsql-hackers@postgresql.org; Mon, 25 Aug 2025 21:45:00 +0000 Received: by mail-io1-xd30.google.com with SMTP id ca18e2360f4ac-886ec1ac877so15620639f.0 for ; Mon, 25 Aug 2025 14:44:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1756158298; x=1756763098; darn=postgresql.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=9m2pFk+3/a9dCvxMEsNLl6SLrx530yvNttz2xF8ZDjU=; b=ma48ZJtYidOw22JzlapWCB6fKDB34CxCxzUjZWxyLTVMU4MMKd1QQVrvf99VyMSMSi dNsBWqoOZuScDUc4sbrOiMKhVTwNFu7ArqnI7P5tA9cA5gkmIZarUI7w4KQ0SqDsahmN IGgvtuj97GyZ8Ar/30Z+XNBFD0T0enjmjwhPTDoGVrVA3fs4ZBdheODRAaFahfCjk96Y hw3ue1o8SD7KBsxLsMv8wx1FdBfG8UdZTQvkp2C5c3yhXqjBHQQgpVZOvOqN79yAw8Nb UAqUwagR32W/924UgYs5O667AJAIAXPov3FVzHmWYrwcXnzhwHh7AwEJlitBIKKKnuJp /Dbw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1756158298; x=1756763098; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=9m2pFk+3/a9dCvxMEsNLl6SLrx530yvNttz2xF8ZDjU=; b=vMNwWl3LWqWTczCVTG9ShoB+e3khwQjx7VwMq+aWhig5dmeG50+GBEk12n8KWSEdkp y0bERDB9bl3JJT3I8B44hdxyDvWj+Mw8FxSNOWLycv0xSfrlJhIHbBFL0lWqjZuNjgzX Xb8SHalTbTq7vp+DegSM07u2hsgi7cSouQfsEergXIvP9ubeHtnUD9gl2p7gnUZhHZIe ia6x8NuRjssNsgF9W7o5tjvSJLI8AEKbtIWChS8kUWB/cRGcVNC02Fa1gP0kaV/MG9BG iXLAfRAgFE6qWfX4DV+4jUd9JSvep6CgoPIqH/REghIqWsH/7qLpdPijp9yfK5gpU5zK gtrQ== X-Forwarded-Encrypted: i=1; AJvYcCVdGoEs4SqME0SMCCtyRXsJqzhMOXPe1rA+bWo6O3xtQR7Dqv49kTiG3Gclj+YwHk0Cbk1sSFNTlL5TiWiJ@postgresql.org X-Gm-Message-State: AOJu0YyeFkCI5pwniaAjH6U9NMN6QYhrC8ycMkoRKsPyAVZF155zKVnv DEUF/RhtFR0Xj3fohqii+lIdWheofp8HOo+jy1LcZ8gk1Fc64qGrvG0K X-Gm-Gg: ASbGncuzP8TItEw/l45VNqIPegY4o7nK5q1CiN82d8inbiJK6RInLA42acrZrUZb4pB JPoYbjWshFXcBfI5OpRlSn0Ub4RqP8kMO46XJBbyzDON3oQCZUN8u59gVDbY94vqcUjVFX6OE7f p/pfAXs0UTGupH+RNVCe6TopySP6i84c4Rkb74+gBjSTyxJvgiDGn67tZRHiMv29nt9EbXsq4xZ mHRMIqDChN9hCuIAzXhRl+DJ+kZIhrMGR3W9X5oQZrMkk8BtTEylWdZ1R4ueb27G/D8lK3Dufj3 Kq5Vlq6+NcFJQKS7zp5/RBX0Gbe8eo6dilteyQvx7Ec9e8pdk2hJ2UgHPUClBKn24PDUlohFCEd dntguhVMoPVXK370ybnOjOIQs6wrgbPkr3RdiP9Xfao0Pyu6X41UVXv/NB2jhvn5ArqNnNToZTQ 7ETRdQFQuFOQ36 X-Google-Smtp-Source: AGHT+IHWEOd/8mMZmkLLy4jgZNLmtt8fpj+JbEGp6eMGwR7oJG0HVoVGjbTgeGARmw4rvgsf/ZxXxQ== X-Received: by 2002:a05:6602:6419:b0:884:705f:707f with SMTP id ca18e2360f4ac-886bd157ee5mr2066156639f.8.1756158298467; Mon, 25 Aug 2025 14:44:58 -0700 (PDT) Received: from nathan (162-195-168-172.lightspeed.stlsmo.sbcglobal.net. [162.195.168.172]) by smtp.gmail.com with ESMTPSA id ca18e2360f4ac-886c8fc6d7fsm542500839f.21.2025.08.25.14.44.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Aug 2025 14:44:57 -0700 (PDT) Date: Mon, 25 Aug 2025 16:44:55 -0500 From: Nathan Bossart To: Sami Imseih Cc: Tom Lane , Andres Freund , Bertrand Drouvot , Rahila Syed , pgsql-hackers Subject: Re: Improve LWLock tranche name visibility across backends Message-ID: References: <5to6tftuml6nkas4jaaljfzecasvslxq3mumeslh74wsol4mzw@rgxpxxlqqwtf> <876523.1755635201@sss.pgh.pa.us> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Archived-At: Precedence: bulk On Mon, Aug 25, 2025 at 04:37:21PM -0500, Sami Imseih wrote: > When we lookup from shared array only, we need to take a shared lock > every lookup. Acquiring that lock is what I am trying to avoid. You > are saying it's not worth optimizing that part, correct? Why do we need a shared lock here? IIUC there's no chance that existing entries will change. We'll only ever add new ones to the end. -- nathan