From: Vladislav Shpilevoy via Tarantool-patches <tarantool-patches@dev.tarantool.org> To: Konstantin Osipov <kostja.osipov@gmail.com>, Serge Petrenko <sergepetrenko@tarantool.org>, gorcunov@gmail.com, tarantool-patches@dev.tarantool.org Subject: Re: [Tarantool-patches] [PATCH v3] wal: introduce limits on simultaneous writes Date: Fri, 26 Feb 2021 21:23:08 +0100 [thread overview] Message-ID: <8a6c0d7e-2231-510c-788d-daa9644f5e84@tarantool.org> (raw) In-Reply-To: <20210226071829.GD18388@starling> On 26.02.2021 08:18, Konstantin Osipov wrote: > * Vladislav Shpilevoy <v.shpilevoy@tarantool.org> [21/02/26 10:15]: >>> I'd also question the place where you decided to put this gate. >>> The source of the issue is async requests, not WAL, which worked >>> fine in absence of async requests. So it's async requests that >>> should be gated, not WAL. >> >> In the commit message it is clearly stated why it is in the >> journal's code, not just in the applier: >> >> The feature is ready for `box.commit{is_async=true}`. Once it's >> implemented, it should check whether the queue is full and let the user >> decide what to do next. Either wait or roll the tx back. >> >> Async transactions will be exposed to 'userspace' to be able to reduce >> latency for network requests ending with a transaction. They won't have >> to wait for WAL write to end. > > You did not understand my comment. I tried to say that a major > part of this code is generic and should reside in lib/core as a > counting semaphore abstraction. Async transaction simply use this > counting semaphore to throttle themselves. Then neither WAL nor > any other resource used by async transactions will be overloaded. > > Otherwise, the system would be allowed to create async > transactions, and while WAL will not overflow, some other resource > (memory, transaction identifiers, whatever) may still overflow. Ok, now I understand. Yeah, I also think it is a good idea to move it libcore if nothing major will change in the patch due to any reason. Talking of the other limits - firstly we need to find if some of them really overflows. Then yes, such a semaphone-thing could be applied there too. But AFAIK, there are no other known similar bugs yet. >>> Otherwise your overflow will just spill out someplace else. >> >> On the contrary. Your proposal to do it in the applier would lead to >> queue overflow in some other place - in userspace. When the queue is >> for the entire WAL, it won't overflow. > > I did not say it should be in the applier. It was a misunderstanding.
next prev parent reply other threads:[~2021-02-26 20:23 UTC|newest] Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-02-24 19:35 Serge Petrenko via Tarantool-patches 2021-02-24 19:40 ` Serge Petrenko via Tarantool-patches 2021-02-25 13:05 ` Konstantin Osipov via Tarantool-patches 2021-02-26 0:57 ` Vladislav Shpilevoy via Tarantool-patches 2021-02-26 7:18 ` Konstantin Osipov via Tarantool-patches 2021-02-26 20:23 ` Vladislav Shpilevoy via Tarantool-patches [this message] 2021-02-26 21:20 ` Konstantin Osipov via Tarantool-patches 2021-02-26 22:44 ` Vladislav Shpilevoy via Tarantool-patches 2021-02-27 13:27 ` Konstantin Osipov via Tarantool-patches 2021-03-01 19:15 ` Serge Petrenko via Tarantool-patches 2021-03-01 21:46 ` Konstantin Osipov via Tarantool-patches 2021-02-26 0:56 ` Vladislav Shpilevoy via Tarantool-patches 2021-03-01 19:08 ` Serge Petrenko via Tarantool-patches 2021-03-01 22:05 ` Vladislav Shpilevoy via Tarantool-patches 2021-03-02 17:51 ` Serge Petrenko via Tarantool-patches 2021-03-03 20:59 ` Vladislav Shpilevoy via Tarantool-patches 2021-03-09 15:10 ` Serge Petrenko via Tarantool-patches 2021-03-09 19:49 ` Vladislav Shpilevoy via Tarantool-patches 2021-03-10 8:18 ` Konstantin Osipov via Tarantool-patches 2021-03-12 17:10 ` Serge Petrenko via Tarantool-patches 2021-03-13 19:14 ` Konstantin Osipov via Tarantool-patches 2021-03-15 23:42 ` Vladislav Shpilevoy via Tarantool-patches 2021-03-16 6:45 ` Konstantin Osipov via Tarantool-patches 2021-03-16 20:27 ` Vladislav Shpilevoy via Tarantool-patches 2021-03-16 10:19 ` Serge Petrenko via Tarantool-patches 2021-03-16 20:48 ` Vladislav Shpilevoy via Tarantool-patches 2021-03-17 12:14 ` Serge Petrenko via Tarantool-patches 2021-03-17 21:02 ` Vladislav Shpilevoy via Tarantool-patches 2021-03-19 11:32 ` Serge Petrenko via Tarantool-patches 2021-03-19 15:36 ` Kirill Yukhin via Tarantool-patches
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