From: Vladimir Davydov <vdavydov.dev@gmail.com> To: Konstantin Osipov <kostja@tarantool.org> Cc: tarantool-patches@freelists.org Subject: Re: [PATCH v2 08/11] replication: rebootstrap instance on startup if it fell behind Date: Thu, 14 Jun 2018 11:58:37 +0300 [thread overview] Message-ID: <20180614085837.do36dza7aizlm4on@esperanza> (raw) In-Reply-To: <20180613205527.GE10632@chai> On Wed, Jun 13, 2018 at 11:55:27PM +0300, Konstantin Osipov wrote: > * Vladimir Davydov <vdavydov.dev@gmail.com> [18/06/08 20:38]: > > If a replica fell too much behind its peers in the cluster and xlog > > files needed for it to get up to speed have been removed, it won't be > > able to proceed without rebootstrap. This patch makes the recovery > > procedure detect such cases and initiate rebootstrap procedure if > > necessary. > > > > Note, rebootstrap is currently only supported by memtx engine. If there > > are vinyl spaces on the replica, rebootstrap will fail. This is fixed by > > the following patches. > > A nitpick, but this makes the whole point of factoring out local > recovery less valid. > > > If local_recovery() can fall back to bootstrap_from_master(), then > the name is misleading. > > Please make sure the control flow and decision making stays in box_cfg(). I rather disagree. Rejoin can be though of as an optional step of the local recovery process. Although we do overwrite local data, we don't purge it - it is still in the local directory and can be recovered upon request. I can, of course, move bootstrap_from_master to box_cfg, but frankly I think it would make the code look worse. > > > > > +bool > > +replicaset_needs_rejoin(struct replica **master) > > +{ > > + replicaset_foreach(replica) { > > + if (replica->applier != NULL && > > + vclock_compare(&replica->applier->gc_vclock, > > + &replicaset.vclock) > 0) { > > + *master = replica; > > + return true; > > + } > > + } > > + *master = NULL; > > + return false; > > +} > > Intuitively this function should return true only if none of the > masters can provide it with necessary logs, not *any* of the > masters. Well, yes, but if an instance fell behind a master, it won't retry to subscribe to it, even after it has synced up with a master that has all xlogs available. I thought about fixing it in the future while leaving it plain and simple for now - rejoin if at least one master reports the replica is stale...
next prev parent reply other threads:[~2018-06-14 8:58 UTC|newest] Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-06-08 17:34 [PATCH v2 00/11] Replica rejoin Vladimir Davydov 2018-06-08 17:34 ` [PATCH v2 01/11] box: retrieve instance uuid before starting local recovery Vladimir Davydov 2018-06-08 17:51 ` Konstantin Osipov 2018-06-08 17:34 ` [PATCH v2 02/11] box: refactor hot standby recovery Vladimir Davydov 2018-06-08 17:34 ` [PATCH v2 03/11] box: retrieve end vclock before starting local recovery Vladimir Davydov 2018-06-14 12:58 ` Konstantin Osipov 2018-06-08 17:34 ` [PATCH v2 04/11] box: open the port " Vladimir Davydov 2018-06-13 20:43 ` Konstantin Osipov 2018-06-14 8:31 ` Vladimir Davydov 2018-06-14 12:59 ` Konstantin Osipov 2018-06-15 15:48 ` [PATCH 0/3] Speed up recovery in case rebootstrap is not needed Vladimir Davydov 2018-06-15 15:48 ` [PATCH 1/3] xlog: erase eof marker when reopening existing file for writing Vladimir Davydov 2018-06-27 17:09 ` Konstantin Osipov 2018-06-15 15:48 ` [PATCH 2/3] wal: rollback vclock on write failure Vladimir Davydov 2018-06-27 17:22 ` Konstantin Osipov 2018-06-15 15:48 ` [PATCH 3/3] wal: create empty xlog on shutdown Vladimir Davydov 2018-06-27 17:29 ` Konstantin Osipov 2018-06-08 17:34 ` [PATCH v2 05/11] box: connect to remote peers before starting local recovery Vladimir Davydov 2018-06-13 20:45 ` Konstantin Osipov 2018-06-14 8:34 ` Vladimir Davydov 2018-06-14 12:59 ` Konstantin Osipov 2018-06-08 17:34 ` [PATCH v2 06/11] box: factor out local recovery function Vladimir Davydov 2018-06-13 20:50 ` Konstantin Osipov 2018-06-08 17:34 ` [PATCH v2 07/11] applier: inquire oldest vclock on connect Vladimir Davydov 2018-06-13 20:51 ` Konstantin Osipov 2018-06-14 8:40 ` Vladimir Davydov 2018-06-08 17:34 ` [PATCH v2 08/11] replication: rebootstrap instance on startup if it fell behind Vladimir Davydov 2018-06-13 20:55 ` Konstantin Osipov 2018-06-14 8:58 ` Vladimir Davydov [this message] 2018-06-08 17:34 ` [PATCH v2 09/11] vinyl: simplify vylog recovery from backup Vladimir Davydov 2018-06-08 17:34 ` [PATCH v2 10/11] vinyl: pass flags to vy_recovery_new Vladimir Davydov 2018-06-13 20:56 ` Konstantin Osipov 2018-06-08 17:34 ` [PATCH v2 11/11] vinyl: implement rebootstrap support Vladimir Davydov 2018-06-10 12:02 ` Vladimir Davydov
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