Tarantool development patches archive
 help / color / mirror / Atom feed
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.

  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=8a6c0d7e-2231-510c-788d-daa9644f5e84@tarantool.org \
    --to=tarantool-patches@dev.tarantool.org \
    --cc=gorcunov@gmail.com \
    --cc=kostja.osipov@gmail.com \
    --cc=sergepetrenko@tarantool.org \
    --cc=v.shpilevoy@tarantool.org \
    --subject='Re: [Tarantool-patches] [PATCH v3] wal: introduce limits on simultaneous writes' \


* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox