[jira] [Commented] (ZOOKEEPER-2464) NullPointerException on ContainerManager

["Johan Forssell (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-2464?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17340178#comment-17340178 ] 

Johan Forssell commented on ZOOKEEPER-2464:
-------------------------------------------

Getting this error again, running *Zookeeper 3.7.0* on a M1 MacBook Pro.


{noformat}
...
zookeeper  | 2021-05-06 12:08:29,290 [myid:1] - ERROR [ContainerManagerTask:ContainerManager$1@103] - Error checking containers
zookeeper  | java.lang.NullPointerException
zookeeper  | 	at org.apache.zookeeper.server.ContainerManager.getCandidates(ContainerManager.java:162)
zookeeper  | 	at org.apache.zookeeper.server.ContainerManager.checkContainers(ContainerManager.java:129)
zookeeper  | 	at org.apache.zookeeper.server.ContainerManager$1.run(ContainerManager.java:97)
zookeeper  | 	at java.base/java.util.TimerThread.mainLoop(Unknown Source)
zookeeper  | 	at java.base/java.util.TimerThread.run(Unknown Source)
{noformat}


> NullPointerException on ContainerManager
> ----------------------------------------
>
>                 Key: ZOOKEEPER-2464
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2464
>             Project: ZooKeeper
>          Issue Type: Bug
>          Components: server
>    Affects Versions: 3.5.1
>            Reporter: Stefano Salmaso
>            Assignee: Jordan Zimmerman
>            Priority: Major
>             Fix For: 3.5.3, 3.6.0
>
>         Attachments: ContainerManagerTest.java, ZOOKEEPER-2464.patch
>
>
> I would like to expose you to a problem that we are experiencing.
> We are using a cluster of 7 zookeeper and we use them to implement a distributed lock using Curator (http://curator.apache.org/curator-recipes/shared-reentrant-lock.html)
> So .. we tried to play with the servers to see if everything worked properly and we stopped and start servers to see that the system worked well
> (like stop 03, stop 05, stop 06, start 05, start 06, start 03)
> We saw a strange behavior.
> The number of znodes grew up without stopping (normally we had 4000 or 5000, we got to 60,000 and then we stopped our application)
> In zookeeeper logs I saw this (on leader only, one every minute)
> 2016-07-04 14:53:50,302 [myid:7] - ERROR [ContainerManagerTask:ContainerManager$1@84] - Error checking containers
> java.lang.NullPointerException
>        at org.apache.zookeeper.server.ContainerManager.getCandidates(ContainerManager.java:151)
>        at org.apache.zookeeper.server.ContainerManager.checkContainers(ContainerManager.java:111)
>        at org.apache.zookeeper.server.ContainerManager$1.run(ContainerManager.java:78)
>        at java.util.TimerThread.mainLoop(Timer.java:555)
>        at java.util.TimerThread.run(Timer.java:505)
> We have not yet deleted the data ... so the problem can be reproduced on our servers



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