[jira] [Updated] (IGNITE-4665) Make near readers update async by default

["Vladimir Ozerov (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IGNITE-4665?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Vladimir Ozerov updated IGNITE-4665:
------------------------------------
    Fix Version/s:     (was: 2.0)
                   2.1

> Make near readers update async by default
> -----------------------------------------
>
>                 Key: IGNITE-4665
>                 URL: https://issues.apache.org/jira/browse/IGNITE-4665
>             Project: Ignite
>          Issue Type: Improvement
>            Reporter: Yakov Zhdanov
>            Priority: Minor
>             Fix For: 2.1
>
>
> Currently when we do cache updates in FULL_SYNC mode we update near readers (near cache entries) synchronously. This is quite big drawback in design, I think. I get each near reader update at cost of 1 extra backup update. I think everyone understands that partitioned cache easily turns to replicated once near readers number increases. In TX cache cost of such updates doubles.
> I do not see any benefit on updating near entries in sync way. Outdated reads can still be possible if I don't read from primary or in TX context.
> So, what I suggest:
> 1. introduce CacheWriteSynchronizationMode.DHT_SYNC (leave PRIMARY_SYNC as default).
> 2. Near entries are updated in async way
> 2.1 in atomic mode together with backup updates
> 2.2 in TX mode after tx is committed on primary. I would also suggest to exclude near readers from lock acquisition/release steps. Only force updates. Updates order will be ensured by single primary node and per-partition striping.
> 3. Near readers do not respond to primary. Once primary fails near readers get invalidated, if primary is alive then communication recovery ensures that message will be delivered to near.
> Here is the discussion on dev list - http://apache-ignite-developers.2346864.n4.nabble.com/Ignite-2-0-Make-near-readers-update-async-by-default-tp14133.html



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