[jboss-jira] [JBoss JIRA] (JGRP-2299) LockService does not work correctly if unlock/lock is called in immediate succession

[David White (Jira)]

     [ https://issues.jboss.org/browse/JGRP-2299?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

David White updated JGRP-2299:
------------------------------
    Attachment: image.png


I tried to test this fix (4.1.2) but unfortunately something seems to be 
broken with the CENTRAL_LOCK2 protocol. 

Upon shutdown, my application successfully closes the JChannel which uses 
the CENTRAL_LOCK2 protocol. However, after the application completely 
exits from all my application code the JVM is still running and never 
exits. It appears there is a thread still running the CENTRAL_LOCK2 
protocol and it is stuck in the method processQueue() on the line 
"req=req_queue.take();}. 

The last version I tested was 4.0.19 so I don't know when this problem was 
introduced. Please advise.

Dave



From:   "Bela Ban (Jira)" <issues at jboss.org>
To:     dfwhite at us.ibm.com
Date:   08/02/2019 08:25 AM
Subject:        [EXTERNAL] [JBoss JIRA] (JGRP-2299) LockService does not 
work correctly if unlock/lock is called in immediate succession





Bela Ban resolved as Done 


 

Resolving this; let me know if this fixes all of your issues!



JGroups / JGRP-2299 
LockService does not work correctly if unlock/lock is called in immediate 
succession 


Change By:
Bela Ban 
Status:
Open Resolved 
Resolution:
Done 




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> LockService does not work correctly if unlock/lock is called in immediate succession
> ------------------------------------------------------------------------------------
>
>                 Key: JGRP-2299
>                 URL: https://issues.jboss.org/browse/JGRP-2299
>             Project: JGroups
>          Issue Type: Bug
>    Affects Versions: 4.0.15
>         Environment: Windows 10 Oracle JDK 1.8 131
> AIX IBM Java 8
>            Reporter: Mirko Streckenbach
>            Assignee: Bela Ban
>            Priority: Major
>             Fix For: 4.1.2
>
>         Attachments: JGroupsExample.java, image.png, udp+lock.xml
>
>
> In our application we have encountered occasional cases of LockService allowing 2 processes to hold the same lock at the same time. I could reproduce this with a simple program (see atttachment) and it happens if for a lock "unlock" is called and immediately afterwards "lock". If there is a small delay (e.g. 1 second) between the two operations everything works as expected.
> This can be produced with the attached program. The program does lock/unlock/lock on a lock and then tries to lock the same lock from a different JChannel and is awarded the lock. If you place a small sleep() after the unlock, everything works as expected and the parallel lock is not awarded.
> If you turn on debugging you'll see no output between unlock and lock, so it looks to me like the lock is awarded without passing GRANT_LOCK messages to the stack. Using a conditional break point you can see that ClientLock.acquired is still true even after the unlock().



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