[jira] [Resolved] (STANBOL-1288) FST Linking Engine EntityCache might contain outdated entries after reregistering the used SolrCore

["Rupert Westenthaler (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/STANBOL-1288?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Rupert Westenthaler resolved STANBOL-1288.
------------------------------------------

    Resolution: Fixed

fixed with http://svn.apache.org/r1572559 for 0.12.1 and http://svn.apache.org/r1572578 in trunk

> FST Linking Engine EntityCache might contain outdated entries after reregistering the used SolrCore
> ---------------------------------------------------------------------------------------------------
>
>                 Key: STANBOL-1288
>                 URL: https://issues.apache.org/jira/browse/STANBOL-1288
>             Project: Stanbol
>          Issue Type: Bug
>          Components: Enhancement Engines
>    Affects Versions: 0.12.0
>            Reporter: Rupert Westenthaler
>            Assignee: Rupert Westenthaler
>             Fix For: 1.0.0, 0.12.1
>
>
> The EntityCacheManager instance of the FST Linking Engine has the same lifecycle as the FSTLinkingEngineComponent. However FSTLinkingEngine instances are created on every change of dependent services (mainly the SolrCore).
> This means that EntityCacheManager will get reused if an external dependency is updated (typically a SolrCore becomes temporarily unavailable).
> The EntityCacheManager provide EntityCache instances for versions (a long provided by the Solr Server). If the version changes a new EntityCache will get created.
> To be affected by this bug the following things need to happen:
> * A FstLinkingEngine with an active EntityCache for a given {version-N} need to be used
> * The SolrCore need to become unavailable
> * The SolrCore need to become available again
> * The new SolrCore need to have different data but the exact same {version-N}
> In this case the EntityCache created for the old SolrCore will be used for the new SolrCore.
> NOTE: This issue does not affect users that update the contents of the SolrCore (e.g. pushing an Entity to an Entityhub Managed site). This only affects users that (re)regsiter a SolrCore on a Managed- or ReferenceSolrServer!
> Affected users will encounter missing linking results. There is also a small possibility of getting NPE while matching linking candidates.
> As Workaround affected users can deactivate the EntityCache by setting its size in the configuration of the engine to '0'.
> To fix this the lifecycle of the EntityCacheMaanger needs to be aligned with the one of the FSTLinkingEngine - meaning a new EntityCacheMaanger needs to be created after every change to a depending service.



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