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Bug 1234806

Summary: [GSS] (6.1.z) Race condition with multiple job executor threads on Oracle
Product: [Retired] JBoss BPMS Platform 6 Reporter: Martin Weiler <mweiler>
Component: jBPM CoreAssignee: Alessandro Lazarotti <alazarot>
Status: CLOSED EOL QA Contact: Radovan Synek <rsynek>
Severity: high Docs Contact:
Priority: high    
Version: 6.1.0CC: kverlaen
Target Milestone: CR1   
Target Release: 6.1.0   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: 1234592 Environment:
Last Closed: 2020-03-27 20:09:35 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1234592    
Bug Blocks: 1249860    

Description Martin Weiler 2015-06-23 09:51:42 UTC 
+++ This bug was initially created as a clone of Bug #1234592 +++

Description of problem:
When using AsyncWorkItemHandler with Oracle, a job can be picked up by two threads when the thread pool size is larger than 1. For queries which use rownum + for update, Hibernate issues not a single query, but breaks this up in two. This allows for the same job being processed by different AvailableJobsExecutor threads:

2015-06-21 12:53:58,489 DEBUG [org.jbpm.executor.impl.AvailableJobsExecutor] (EJB default - 10) Executor Thread org.jbpm.executor.impl.AvailableJobsExecutor@434eb850 Waking Up!!!
2015-06-21 12:53:58,489 DEBUG [org.jbpm.executor.impl.AvailableJobsExecutor] (EJB default - 9) Executor Thread org.jbpm.executor.impl.AvailableJobsExecutor@6d182f77 Waking Up!!!
2015-06-21 12:53:58,490 INFO  [stdout] (EJB default - 10) Hibernate: select * from ( select requestinf0_.id...) ) where rownum <= ?

2015-06-21 12:53:58,492 INFO  [stdout] (EJB default - 9) Hibernate: select * from ( select requestinf0_.id ...) ) where rownum <= ?

2015-06-21 12:53:58,556 INFO  [stdout] (EJB default - 10) Hibernate: select id from RequestInfo where id =? for update

2015-06-21 12:53:58,559 INFO  [stdout] (EJB default - 9) Hibernate: select id from RequestInfo where id =? for update

This shows that both threads can obtain the same job instance, as outlined in the related Hibernate issue:
"Yes it does allow a slight possibility that a row might be updated or locked between the initial select (paging) and the subsequent lock attempt." from https://hibernate.atlassian.net/browse/HHH-1168?focusedCommentId=48846&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-48846
Comment 2 Maciej Swiderski 2015-08-14 16:26:52 UTC 
backported to 6.2.x branch:
jbpm
https://github.com/droolsjbpm/jbpm/commit/6258b2352f1f927484a334b224d66ad6b7728d04
https://github.com/droolsjbpm/jbpm/commit/d5b5bf0a0cfa1c4d07403f849f16f8951faf0b1b
Comment 4 Tomas Livora 2015-09-01 12:50:00 UTC 
Verified on BPMS 6.1.3 CR1