[infinispan-issues] [JBoss JIRA] (ISPN-4137) Transaction executed multiple times due to forwarded CommitCommand

[Dan Berindei (JIRA)]

    [ https://issues.jboss.org/browse/ISPN-4137?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12956015#comment-12956015 ] 

Dan Berindei commented on ISPN-4137:
------------------------------------

Indeed [~rvansa], waiting for a human intervention doesn't sound very good. Before starting the work on this I was convinced that's how recovery is supposed to work, now I'm not so sure...

Without recovery, we will still run the rollback to make sure the locks are released. I don't have any suggestions on how to improve that, except maybe retrying the commit indefinitely.

If the primary owner crashes, the txs on the backup owners still have "backup locks". Each prepare on the new primary owner will check in the entire tx table for backup locks, and will block until those locks are released. The real problem is when the originator dies...
                
> Transaction executed multiple times due to forwarded CommitCommand
> ------------------------------------------------------------------
>
>                 Key: ISPN-4137
>                 URL: https://issues.jboss.org/browse/ISPN-4137
>             Project: Infinispan
>          Issue Type: Bug
>          Components: State Transfer, Transactions
>            Reporter: Radim Vansa
>            Assignee: Dan Berindei
>            Priority: Critical
>
> When the {{StateTransferInterceptor}} forwards a CommitCommand for the new topology, multiple CommitCommands may be broadcast across the cluster. If the command (forwarded already from originator) times out, the transaction may be correctly finished by the first one and the application considers TX as succeeded (useSynchronizations=true), although one more Rollback is sent as well.
> Then, again in STI, when the CommitCommand arrives with higher topologyId than the one used for the first TX execution, another artificial Prepare (followed by the commit) is executed - see {{STI.visitCommitCommand}}.
> However, this execution may be delayed a lot and originator may have already executed another TX on the same entries. Then, this forwarded Commit will overwrite the already updated entries, causing inconsistency of data.

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