[infinispan-issues] [JBoss JIRA] (ISPN-3048) Eviction needs to be transactional

[Pedro Ruivo (JIRA)]

    [ https://issues.jboss.org/browse/ISPN-3048?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12922463#comment-12922463 ] 

Pedro Ruivo commented on ISPN-3048:
-----------------------------------

hi [~pferraro]

I'm not convinced that the eviction needs to be transactional. It happens under the segment lock in the hash map and it is saved to disk before it is removed from the [in memory] map. Also, if a retrieve operation happens at the same time and the entry is not longer in memory, it is going to look at the cache loader. So, looking at the code, I don't see where the retrieve operation can return null but I'm going to try to do some tests around it.

Anyway, do we have any some kind of discussion to turn the eviction transactional? personally, I don't like the idea...

finally, are you sure that you are not hitting this: https://issues.jboss.org/browse/ISPN-3694
Does it happen with passivation disabled?

thanks!
                
> Eviction needs to be transactional
> ----------------------------------
>
>                 Key: ISPN-3048
>                 URL: https://issues.jboss.org/browse/ISPN-3048
>             Project: Infinispan
>          Issue Type: Bug
>          Components: Eviction
>    Affects Versions: 5.3.0.Alpha1
>            Reporter: Paul Ferraro
>            Assignee: Pedro Ruivo
>            Priority: Critical
>              Labels: 620
>             Fix For: 6.0.0.Final
>
>
> Currently, Infinispan eviction is non-transactional.  This makes Infinispan's eviction manager virtually unusable, since non-transactional eviction can cause phantom reads and data loss because it violates the isolation of concurrent transactions.  This is especially problematic when using a passivation-enabled cache store.  In this case, a cache eviction/passivation can cause a concurrently executed cache retrieval to return null - even though the act of passivation does not change the data - it only changes where it is stored.
> We work around this in the AS by performing eviction manually, using pessimistic locking in combination with eager lock acquisition prior to eviction.  This is unfortunate, since it prevents me from leveraging Infinispan's build-in eviction strategies.

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