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Posted to issues@activemq.apache.org by "Jamie goodyear (JIRA)" <ji...@apache.org> on 2018/07/18 15:44:00 UTC
[jira] [Commented] (AMQ-7013) XATransactionID hash function may
generate duplicates.
[ https://issues.apache.org/jira/browse/AMQ-7013?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16547978#comment-16547978 ]
Jamie goodyear commented on AMQ-7013:
-------------------------------------
Please see PR'd unit test:
[https://github.com/apache/activemq/pull/288]
The hash function was bad, returning 131077.
After discussing with Chrino on apache-activemq IRC room, decided to try JenkinsHash to perform hash generation.
Now we get unique hashes in this scenario.
> XATransactionID hash function may generate duplicates.
> ------------------------------------------------------
>
> Key: AMQ-7013
> URL: https://issues.apache.org/jira/browse/AMQ-7013
> Project: ActiveMQ
> Issue Type: Bug
> Reporter: Jamie goodyear
> Priority: Major
>
> XATransactionID hash function may generate duplicates.
> Scenario:
> XID formatId, GlobalTransaction, and BranchQualifier values are identical for many entries. We need to use a better hash function to avoid populating a map with many entries in the same bucket (results in bucket having O(n) performance on recovery).
> Example using existing Hash Function:
> 2018-07-18 06:13:29,866 | INFO | Recovering from the journal @1:28 | org.apache.activemq.store.kahadb.MessageDatabase | main
> 2018-07-18 06:23:04,070 | INFO | @2:484592, 100000 entries recovered .. | org.apache.activemq.store.kahadb.MessageDatabase | main
> 2018-07-18 06:23:04,099 | INFO | Recovery replayed 100453 operations from the journal in 574.233 seconds. | org.apache.activemq.store.kahadb.MessageDatabase | main
> Using JenkinsHash:
> 2018-07-18 10:58:43,713 | INFO | Recovering from the journal @1:28 | org.apache.activemq.store.kahadb.MessageDatabase | main
> 2018-07-18 10:58:51,302 | INFO | @2:484592, 100000 entries recovered .. | org.apache.activemq.store.kahadb.MessageDatabase | main
> 2018-07-18 10:58:51,329 | INFO | Recovery replayed 100453 operations from the journal in 7.618 seconds. | org.apache.activemq.store.kahadb.MessageDatabase | main
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