[infinispan-issues] [JBoss JIRA] (ISPN-5515) Preload only on the node that starts up the first

[Sanne Grinovero (JIRA)]

    [ https://issues.jboss.org/browse/ISPN-5515?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13072335#comment-13072335 ] 

Sanne Grinovero commented on ISPN-5515:
---------------------------------------

What guarantees do you have for this data to be valid? The definition of "first" seems rather subjective to me, and you have no idea how long ago that data was stored. Maybe this node has been down for the last month, while all other nodes worked and now this is being restarted.


> Preload only on the node that starts up the first
> -------------------------------------------------
>
>                 Key: ISPN-5515
>                 URL: https://issues.jboss.org/browse/ISPN-5515
>             Project: Infinispan
>          Issue Type: Enhancement
>          Components: Core, Loaders and Stores
>    Affects Versions: 7.2.2.Final, 8.0.0.Alpha1
>            Reporter: Dan Berindei
>            Assignee: Dan Berindei
>             Fix For: 8.0.0.Alpha2
>
>
> Preloading happens before communicating with other nodes that might already have the cache running. When joining the existing members, the cache then waits to receive the first CH in which it is a member, and then deletes only the entries in the segments that it doesn't own in that CH.
> The intention of this was to remove as little as possible from the existing data, e.g. if the first node to start up is not the one that was stopped last. But the preloaded entries are not replicated to the other nodes, so this can lead to inconsistencies.
> It would be better to delay preloading until we know we are the first node to start up, but failing that we could clear the data container and the store before receiving the initial state.
> Note that this will only allow preloading data from one node. Restoring data from more nodes is harder to do, and we will implement it as part of graceful restart.



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