[infinispan-issues] [JBoss JIRA] (ISPN-61) Dynamically switch between single and two phase commit based on cluster size

[Mircea Markus (JIRA)]

     [ https://issues.jboss.org/browse/ISPN-61?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mircea Markus resolved ISPN-61.
-------------------------------

    Resolution: Rejected


total order is a better alternative
                
> Dynamically switch between single and two phase commit based on cluster size
> ----------------------------------------------------------------------------
>
>                 Key: ISPN-61
>                 URL: https://issues.jboss.org/browse/ISPN-61
>             Project: Infinispan
>          Issue Type: Feature Request
>    Affects Versions: 4.0.0.ALPHA4
>            Reporter: Mircea Markus
>            Assignee: Mircea Markus
>
> Following 2 optimizations might be implemented with respect to transactions.
> 1) From an email on infinispan-dev (horizon-dev actually):
> if there are only two members int the cluster always use an 1PC. If the 1st phase fails remotely, then also rollback locally. This would reduce one network roundtrip.
> While this is an interesting thought, it does raise the potential for race conditions - since this decision will have to be taken in the TxInterceptor in the beforeCompletion phase of a transaction, and by the time the call gets to the interceptor for replication, the topology may have changed such that you need to replicate to 2 instead of 1 other peer.  Which would mean a 2PC again.  So it does need some thought.
> 2)  when asked to prepare, a participant might return a value indicating that no changes were made (read-only participant), so this one won't need an commit message, so less roundtrip.

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