[jira] [Assigned] (HIVE-11987) CompactionTxnHandler.createValidCompactTxnList() can use much less memory

["Eugene Koifman (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-11987?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Eugene Koifman reassigned HIVE-11987:
-------------------------------------

    Assignee:     (was: Eugene Koifman)

> CompactionTxnHandler.createValidCompactTxnList() can use much less memory
> -------------------------------------------------------------------------
>
>                 Key: HIVE-11987
>                 URL: https://issues.apache.org/jira/browse/HIVE-11987
>             Project: Hive
>          Issue Type: Improvement
>          Components: Metastore, Transactions
>    Affects Versions: 1.1.0
>            Reporter: Eugene Koifman
>            Priority: Minor
>
> This method only needs HWM and list of txn IDs in 'a' state and smallest 'o' txn id.
> It's currently implemented to get the list from TxnHandler.getOpenTxnsInfo(),
> which returns (txn id, state, host, user) for each txn and includes Aborted txns.
> This can easily be 120 bytes or more per txn overhead (over 1 Java long) which not an issue in general but when the system is misconfigured, the number of opened/aborted txns can get into the millions.  This creates unnecessary memory pressure on metastore.
> Should consider fixing this.
> This should be easy to fix since the result of getOpenTxnsInfo() doesn't go over the wire.
> Also, ValidCompactorTxnList doesn't actually need to store the 'o' txn ids, just the 'a' ones.



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