[AMQ-7013] XATransactionID hash function may generate duplicates.

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 5.15.5, 5.16.0
• Assignee: Unassigned
• Reporter: Jamie Mark Goodyear
• Created: 18/Jul/18 13:58
• Updated: 18/Jul/18 21:16
• Resolved: 18/Jul/18 16:43

Description

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 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