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https://issues.apache.org/jira/browse/HIVE-11987?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14979693#comment-14979693
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Lefty Leverenz commented on HIVE-11987:
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Acronym clarification: HWM means high water mark.
> CompactionTxnHandler.createValidCompactTxnList() can use much less memory
> -------------------------------------------------------------------------
>
> Key: HIVE-11987
> URL: https://issues.apache.org/jira/browse/HIVE-11987
> Project: Hive
> Issue Type: Bug
> Components: Metastore, Transactions
> Affects Versions: 1.1.0
> Reporter: Eugene Koifman
> Assignee: 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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