From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from localhost (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 937B9255F3 for ; Thu, 25 Jul 2019 05:26:42 -0400 (EDT) Received: from turing.freelists.org ([127.0.0.1]) by localhost (turing.freelists.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id V30Xcs1HM7CR for ; Thu, 25 Jul 2019 05:26:42 -0400 (EDT) Received: from smtp34.i.mail.ru (smtp34.i.mail.ru [94.100.177.94]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTPS id 53DDF255F1 for ; Thu, 25 Jul 2019 05:26:42 -0400 (EDT) Date: Thu, 25 Jul 2019 12:26:40 +0300 From: Konstantin Osipov Subject: [tarantool-patches] Re: [PATCH] Output of fiber.info will contain only non-idle fibers Message-ID: <20190725092640.GJ15185@atlas> References: <20190723195643.GA18567@atlas> <2274932.tPdvVCckH0@home.lan> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2274932.tPdvVCckH0@home.lan> Sender: tarantool-patches-bounce@freelists.org Errors-to: tarantool-patches-bounce@freelists.org Reply-To: tarantool-patches@freelists.org List-Help: List-Unsubscribe: List-software: Ecartis version 1.0.0 List-Id: tarantool-patches List-Subscribe: List-Owner: List-post: List-Archive: To: =?utf-8?B?0JPQtdC+0YDQs9C40Lkg0JrQuNGA0LjRh9C10L3QutC+?= Cc: tarantool-patches@freelists.org * Георгий Кириченко [19/07/25 10:05]: > On Tuesday, July 23, 2019 10:56:43 PM MSK Konstantin Osipov wrote: > > * Maria K [19/07/23 21:01]: > > > The output used to be too cluttered due to idle ones. > > > > > > Closes #4235 > > > > @kyukhin, first, please I don't get how does this get scheduled to a > > milestone? How does this follow triage guidelines? > > > > Please don't schedule anything that is not a priority, even if > > it's a noob issue, since it takes time of everyone involved. > I think anybody is free to send a patch to the public tarantool > mailing list despite the issue milestone (if they is not bound > by employee duties). Also it was a 'good first issue' ticket to > start a candidate on boarding. The reason it was a good first issue is that the problem was wrongly defined in the first place. As defined, it had a trivial solution. The mere fact we have a disagreement suggests the label was applied incorrectly. > > fiber.info() already doesn't show anything from cord->dead list. > > Fibers which are stuck in a pool are performing application-level > > code, even if it's a built in pool, so contribute valuable > > information to fiber.info() output. Besides, it's always easy to > > filter out any class of fibers with luafun. > It is not easy to filter out such fibers. In the other hand tx fiber pool is 'a > hack' to spare some fiber structures between invocations. So fiber pool cached > fibers could/should be threatened as dead ones. Well, I don't think everyone should be unconditionally deprived of this data if someone can't write a single-line snippet with luafun. > > Finally, there are other types of pools -- an application-level pool > > in Lua will have lots of idle fibers in it. > An application level fiber pool uses some user-defined condition with exactly- > defied meaning and state. And it isn't the same as the tx fiber pool. An > appplication fiber (in pool or not) is the resource managed by user while tx > fiber pool is not. And I see no point in seeing an idle fiber from tx fiber pool. I disagree there is no point in seeing these fibers. They take up fiber stack and contribute to the total list libev events/fibers the scheduler has to deal with. > > In other words, this is an partial fix of a raw feature > > request. > > > > Tarantool instrumentation sucks, but it doesn't mean it should be > > patched by quick hacks here and there. > > > > A nice and general solution would be to compress mostly identical > > fiber.info() entries. But I guess it's not a noob task. > I didn't find your suggestion solution nice and general in case of filtering > idle fibers out. Another way of properly fixing it would be to more aggressively/carefully expire such fibers from the pool. If you look at the current idle callback implementation there are a few flaws in it: - there is a standalone idle callback, rather than fiber idle timeout, and the callback removes no more than 1 fiber per second - when the idle callback wakes up a fiber, it doesn't necessarily die. It looks at the pool->output first, and if there are messages in the output, works on them. Which is apparently wrong, because there always messages in the list on a busy system, this doesn't mean the idle fiber should be the one to work them off. *None* of this would be visible/bothering anybody if this information was hidden from fiber.info(). So this begs the question: why am I wasting time discussing/explaining this, how did it suddenly become a priority, which I asked in the beginning of this thread. -- Konstantin Osipov, Moscow, Russia