Tarantool development patches archive
 help / color / mirror / Atom feed
From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Konstantin Osipov <kostja.osipov@gmail.com>
Cc: tml <tarantool-patches@dev.tarantool.org>
Subject: Re: [Tarantool-patches] [PATCH v5 3/5] box/applier: fix nil dereference in applier rollback
Date: Wed, 5 Feb 2020 13:48:17 +0300	[thread overview]
Message-ID: <20200205104817.GM12445@uranus> (raw)
In-Reply-To: <20200205095524.GD4624@atlas>

On Wed, Feb 05, 2020 at 12:55:24PM +0300, Konstantin Osipov wrote:
> * Cyrill Gorcunov <gorcunov@gmail.com> [20/02/05 11:31]:
> > > I don't understand this comment. How can it be lost exactly?
> > 
> > Hmmm, I think you're right. Actually unweaving the all possible
> > call traces by hands (which I had to do) is quite exhausting task
> > so I might be wrong here.
> 
> It was added by parallel applier patch, so the most likely cause
> of the bug is that this way of cancelling parallel appliers on
> conflict was not tested well enough. Previously we only had a
> single applier per peer so did not need to coordinate.

I see, thanks!

> > > Let's begin by explaining why we need to cancel the reader fiber here.
> > 
> > This fiber_cancel has been already here, I only added diag_set(FiberIsCancelled)
> > to throw an exception thus the caller would zap this applier fiber.
> > Actually I think we could retry instead of reaping off the fiber
> > completely but it requies more deep understanding of how applier
> > works. So I left it in comment.
> 
> No, we can't and shouldn't retry. Retry handling is done elsewhere already -
> see replication_skip_conflict.

Sure, will do, thanks for pointing.

> If replication is stopped by an apply error, it's most likely a
> transaction conflict, indicating that active-active setup is
> broken, so it has to be resolved by a DBA (which can set
> replication_skip_conflict). This is why it's critical to preserve
> the original error.
> > 
> > Not exactly, if I understand the initial logic of this applier
> > try/cath branch  we need to setup replicaset.applier.diag and
> > then on FiberIsCancelled we should move it from replicaset.applier.diag
> > back to current fiber->diag.
> 
> Please dig into what is "current" here. Which fiber is current if
> there are many fibers handling a single peer?

Will do, tahnks!

  reply	other threads:[~2020-02-05 10:48 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-27 21:53 [Tarantool-patches] [PATCH v5 0/5] box/replication: add missing diag set and fix sigsegv Cyrill Gorcunov
2020-01-27 21:53 ` [Tarantool-patches] [PATCH v5 1/5] box/request: add missing OutOfMemory diag_set Cyrill Gorcunov
2020-01-27 21:53 ` [Tarantool-patches] [PATCH v5 2/5] box/applier: add missing diag_set on region_alloc failure Cyrill Gorcunov
2020-01-27 21:53 ` [Tarantool-patches] [PATCH v5 3/5] box/applier: fix nil dereference in applier rollback Cyrill Gorcunov
2020-02-04 22:11   ` Konstantin Osipov
2020-02-05  8:27     ` Cyrill Gorcunov
2020-02-05  9:55       ` Konstantin Osipov
2020-02-05 10:48         ` Cyrill Gorcunov [this message]
2020-01-27 21:53 ` [Tarantool-patches] [PATCH v5 4/5] errinj: add ERRINJ_REPLICA_TXN_WRITE Cyrill Gorcunov
2020-02-04 22:11   ` Konstantin Osipov
2020-01-27 21:53 ` [Tarantool-patches] [PATCH v5 5/5] test: add replication/applier-rollback Cyrill Gorcunov
2020-01-28  8:26   ` [Tarantool-patches] [PATCH v6 " Cyrill Gorcunov
2020-01-28 14:23 ` [Tarantool-patches] [PATCH v5 0/5] box/replication: add missing diag set and fix sigsegv Cyrill Gorcunov

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:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

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

  git send-email \
    --in-reply-to=20200205104817.GM12445@uranus \
    --to=gorcunov@gmail.com \
    --cc=kostja.osipov@gmail.com \
    --cc=tarantool-patches@dev.tarantool.org \
    --subject='Re: [Tarantool-patches] [PATCH v5 3/5] box/applier: fix nil dereference in applier rollback' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* 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