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From: Vladislav Shpilevoy via Tarantool-patches <tarantool-patches@dev.tarantool.org>
To: Serge Petrenko <sergepetrenko@tarantool.org>, gorcunov@gmail.com
Cc: tarantool-patches@dev.tarantool.org
Subject: Re: [Tarantool-patches] [PATCH 3/7] txn_limbo: fix promote term filtering
Date: Sat, 19 Jun 2021 00:49:21 +0200
Message-ID: <d309c8a4-3cbb-c3b1-7d75-a162b63ab6fe@tarantool.org> (raw)
In-Reply-To: <ac4faddb-5579-06b0-bde0-049a99f87a9e@tarantool.org>

Hi! Thanks for the fixes!

> 15.06.2021 23:57, Vladislav Shpilevoy пишет:
>> Thanks for the patch!
>>
>> On 10.06.2021 15:32, Serge Petrenko via Tarantool-patches wrote:
>>> txn_limbo_process() used to filter out promote requests whose term was
>>> equal to the greatest term seen. This wasn't correct for PROMOTE entries
>>> with term 1.
>>>
>>> Such entries appear after box.ctl.promote() is issued on an instance
>>> with disabled elections. Every PROMOTE entry from such an instance has
>>> term 1, but should still be applied. Fix this in the patch.
>> Didn't we agree that PROMOTE should bump the term always? I see no purpose
>> for the PROMOTE which never bumps the term except for the tests, but for
>> such occasion it would be better to have internal.make_leader() or something
>> which bypasses everything. Although the best option would to bump the term
>> always.
>>
>> I see you did something in the last commit about that, but the part
>> about `limbo->promote_greatest_term > 1` still remains. It looks very
>> illegal to point out some terms as "special".
> 
> What about old instances?
> They may issue multiple promotes for the same term when elections are off.

What if they issue multiple promotes for the same term > 1? They could have
elections enabled, then the term was bumped a few times, then elections were
turned off again. Next promotes will use the current term which is > 1,
won't they?

> Previous behaviour (wrong, because we forgot to filter out too old promotes at all)
> made the instance apply all such promotes.
> 
> I thought we should allow multiple promotes, at least for the default term (1), which
> happen only when elections are turned off and have never been turned on.
> 
> Otherwise, having a new instance together with the old one in the same cluster,
> you'll have one of them apply all the promotes for one term, and have one dataset,
> and the other ignore all but the first promote, and have possibly different data.> I did fix the issue in the last commit. All the new instances will issue promotes with
> increasing term each time, and the term will be >= 2.
> 
> So all the promotes with term == 1 surely will be from the old instances.

  reply	other threads:[~2021-06-18 22:49 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-10 13:32 [Tarantool-patches] [PATCH 0/7] forbid implicit limbo ownership transition Serge Petrenko via Tarantool-patches
2021-06-10 13:32 ` [Tarantool-patches] [PATCH 1/7] replication: always send raft state to subscribers Serge Petrenko via Tarantool-patches
2021-06-10 16:47   ` Cyrill Gorcunov via Tarantool-patches
2021-06-11  8:43     ` Serge Petrenko via Tarantool-patches
2021-06-11  8:44       ` Cyrill Gorcunov via Tarantool-patches
2021-06-15 20:53   ` Vladislav Shpilevoy via Tarantool-patches
2021-06-17 21:00     ` Serge Petrenko via Tarantool-patches
2021-06-10 13:32 ` [Tarantool-patches] [PATCH 2/7] replication: forbid implicit limbo owner transition Serge Petrenko via Tarantool-patches
2021-06-15 20:55   ` Vladislav Shpilevoy via Tarantool-patches
2021-06-17 21:00     ` Serge Petrenko via Tarantool-patches
2021-06-18 22:49   ` Vladislav Shpilevoy via Tarantool-patches
2021-06-21 10:13     ` Serge Petrenko via Tarantool-patches
2021-06-10 13:32 ` [Tarantool-patches] [PATCH 3/7] txn_limbo: fix promote term filtering Serge Petrenko via Tarantool-patches
2021-06-15 20:57   ` Vladislav Shpilevoy via Tarantool-patches
2021-06-17 21:00     ` Serge Petrenko via Tarantool-patches
2021-06-18 22:49       ` Vladislav Shpilevoy via Tarantool-patches [this message]
2021-06-21  8:55         ` Serge Petrenko via Tarantool-patches
2021-06-10 13:32 ` [Tarantool-patches] [PATCH 4/7] txn_limbo: persist the latest effective promote in snapshot Serge Petrenko via Tarantool-patches
2021-06-15 20:59   ` Vladislav Shpilevoy via Tarantool-patches
2021-06-17 21:00     ` Serge Petrenko via Tarantool-patches
2021-06-10 13:32 ` [Tarantool-patches] [PATCH 5/7] replication: send latest effective promote in initial join Serge Petrenko via Tarantool-patches
2021-06-15 21:00   ` Vladislav Shpilevoy via Tarantool-patches
2021-06-17 21:00     ` Serge Petrenko via Tarantool-patches
2021-06-18 22:52       ` Vladislav Shpilevoy via Tarantool-patches
2021-06-21 10:12         ` Serge Petrenko via Tarantool-patches
2021-06-10 13:32 ` [Tarantool-patches] [PATCH 6/7] box: introduce `box.ctl.demote` Serge Petrenko via Tarantool-patches
2021-06-18 22:52   ` Vladislav Shpilevoy via Tarantool-patches
2021-06-21 14:56     ` Serge Petrenko via Tarantool-patches
2021-06-10 13:32 ` [Tarantool-patches] [PATCH 7/7] box: make promote/demote always bump the term Serge Petrenko via Tarantool-patches
2021-06-15 21:00   ` Vladislav Shpilevoy via Tarantool-patches
2021-06-17 21:00     ` Serge Petrenko via Tarantool-patches
2021-06-18 22:53   ` Vladislav Shpilevoy via Tarantool-patches
2021-06-21 15:02     ` Serge Petrenko via Tarantool-patches
2021-06-15 20:53 ` [Tarantool-patches] [PATCH 0/7] forbid implicit limbo ownership transition Vladislav Shpilevoy via Tarantool-patches

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