[infinispan-issues] [JBoss JIRA] (ISPN-3422) In non-tx caches, write operations may not be atomic during rebalance

[Radim Vansa (JIRA)]

    [ https://issues.jboss.org/browse/ISPN-3422?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12824610#comment-12824610 ] 

Radim Vansa commented on ISPN-3422:
-----------------------------------

I have a feeling (already mentioned in ISPN-3600) that the ignorePreviousValue is rather abused, as even with the flag set we would do the comparison, and with the flag set to false on non-origin nodes the command is ignored at all in perform()... I know this is an implementation detail, but the flag name does not correspond to the use at all.

ad 1) I don't quite understand the problem - conditional commands already require equals implementation on values or defined valueEquivalence within the command


                
> In non-tx caches, write operations may not be atomic during rebalance
> ---------------------------------------------------------------------
>
>                 Key: ISPN-3422
>                 URL: https://issues.jboss.org/browse/ISPN-3422
>             Project: Infinispan
>          Issue Type: Bug
>            Reporter: Dan Berindei
>            Assignee: Dan Berindei
>            Priority: Critical
>              Labels: jdg62blocker
>             Fix For: 6.0.0.CR2, 6.0.0.Final
>
>
> If the cache topology changes while a write command is running and before it has actually committed the entry to the data container, we retry the command (see ISPN-3366 and ISPN-3357). But before we detect the topology change, one or more of the backup owners may have already applied the modification.
> Retrying the command re-acquires the key lock on the primary owner (even if the primary owner didn't change). That means another command could have modified the same key in the meantime, but the retried command is going to ignore any changes and is going to return the value before the first attempt. Obviously, the command is not retried if the first attempt is not successful, but scenarios like this are possible:
> {code}
> thread 1: putIfAbsent(k, v1) -> null
> thread 2: putIfAbsent(k, v2) -> null
> {code}

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