From: Konstantin Osipov <kostja@tarantool.org>
To: "Георгий Кириченко" <georgy@tarantool.org>
Cc: tarantool-patches@freelists.org
Subject: [tarantool-patches] Re: [PATCH] Do not enable commit if read_only = true
Date: Mon, 4 Mar 2019 12:41:42 +0300 [thread overview]
Message-ID: <20190304094142.GA30799@chai> (raw)
In-Reply-To: <1779552.GDyJA9gWEY@home.lan>
* Георгий Кириченко <georgy@tarantool.org> [19/03/03 23:50]:
> On Thursday, February 28, 2019 1:25:30 PM MSK Konstantin Osipov wrote:
> > * Vladimir Davydov <vdavydov.dev@gmail.com> [19/02/27 12:26]:
> > > On Wed, Feb 27, 2019 at 10:36:00AM +0300, Georgy Kirichenko wrote:
> > > > Disable commit if server is in read only mode.
> > >
> > > The commit message is very poor. Please elaborate why this is important.
> >
> > Having thought about it we should go over all in-flight
> > transactions in vinyl and abort them.
> >
> > We already use this approach on DDL.
> > We could make it more general.
> I did a little investigation and found that current implementation does not
> allow us do reach expected behavior using vinyl aborts because of
> * transaction placed in the write set only after uniqueness
> check - this leads
> to a race if read only was set during this check.
tx_manager_abort_writers() looks for a single lsm only anyway. In
case of read-only you need to abort all write transactions
against all spaces.
You have two broad options with this problem: fix the existing
infrastructure or begin building a new one.
Adding an extra check to txn_commit() is neither. You will have
two checks for read_only, but your ddl will continue to be broken.
For example, the problem you mention about vinyl write
transactions being added to tx_manager->writers after yield also
affects vinyl ddl. By adding an extra read_only check to
txn_commit() you won't fix it.
So I think we should first consider fixing tx_manager->writers list, so
that transactions end up in this list before yield, and
implementing vy_tx_about_writers() for all write transactions. I
asked Vova to look into this since this is vinyl domain and a bit
tricky one.
--
Konstantin Osipov, Moscow, Russia, +7 903 626 22 32
http://tarantool.io - www.twitter.com/kostja_osipov
prev parent reply other threads:[~2019-03-04 9:41 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-27 7:36 [tarantool-patches] " Georgy Kirichenko
2019-02-27 9:02 ` Vladimir Davydov
2019-02-28 10:25 ` [tarantool-patches] " Konstantin Osipov
2019-03-03 20:49 ` Георгий Кириченко
2019-03-04 9:41 ` Konstantin Osipov [this message]
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