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https://issues.apache.org/jira/browse/FLINK-5996?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17273760#comment-17273760
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Yordan Pavlov edited comment on FLINK-5996 at 1/28/21, 2:18 PM:
----------------------------------------------------------------

Discovered this ticket looking for explanation of Flink behavior regarding 
Zookeeper node being down. We are running in Kubernetes and have 3 ZK nodes in 
our setup, having 2 out of 3 running makes a quorum, still what I am observing 
is that even when one ZK is down we see this:


{code:java}
[main-EventThread] INFO  
o.a.f.s.c.o.a.curator.framework.state.ConnectionStateManager  - State change: 
SUSPENDED
[Curator-ConnectionStateManager-0] WARN  
o.a.f.runtime.leaderelection.ZooKeeperLeaderElectionService  - Connection to 
ZooKeeper suspended. The contender LeaderContender: DefaultDispatcherRunner no 
longer participates in the leader election.
[flink-akka.actor.default-dispatcher-27] INFO  
o.a.flink.runtime.resourcemanager.StandaloneResourceManager  - Closing 
TaskExecutor connection 7c61bd584aa71bb1ff998234fff90cde because: 
ResourceManager leader changed to new address null

{code}


which basically restarts the job. Is my understanding correct, and if so isn't 
this considered a Flink problem?


was (Author: yordanpavlov):
Discovered this ticket looking for explanation of Flink behavior regarding 
Zookeeper node being down. We are running in Kubernetes and have 3 ZK nodes in 
our setup, having 2 out of 3 running makes a quorum, still what I am observing 
is that even when one ZK is down we see this:

{{[main-EventThread] INFO  
o.a.f.s.c.o.a.curator.framework.state.ConnectionStateManager  - State change: 
SUSPENDED
[Curator-ConnectionStateManager-0] WARN  
o.a.f.runtime.leaderelection.ZooKeeperLeaderElectionService  - Connection to 
ZooKeeper suspended. The contender LeaderContender: DefaultDispatcherRunner no 
longer participates in the leader election.
[flink-akka.actor.default-dispatcher-27] INFO  
o.a.flink.runtime.resourcemanager.StandaloneResourceManager  - Closing 
TaskExecutor connection 7c61bd584aa71bb1ff998234fff90cde because: 
ResourceManager leader changed to new address null
}}

which basically restarts the job. Is my understanding correct, and if so isn't 
this considered a Flink problem?

> Jobmanager HA should not crash on lost ZK node
> ----------------------------------------------
>
>                 Key: FLINK-5996
>                 URL: https://issues.apache.org/jira/browse/FLINK-5996
>             Project: Flink
>          Issue Type: Bug
>          Components: Runtime / Coordination
>    Affects Versions: 1.2.0
>            Reporter: Gyula Fora
>            Assignee: Dominik WosiƄski
>            Priority: Major
>
> Even if there are multiple zk hosts configured the jobmanager crashes if one 
> of them is lost:
> org.apache.flink.shaded.org.apache.curator.CuratorConnectionLossException: 
> KeeperErrorCode = ConnectionLoss
>       at 
> org.apache.flink.shaded.org.apache.curator.ConnectionState.checkTimeouts(ConnectionState.java:197)
>       at 
> org.apache.flink.shaded.org.apache.curator.ConnectionState.getZooKeeper(ConnectionState.java:87)
>       at 
> org.apache.flink.shaded.org.apache.curator.CuratorZookeeperClient.getZooKeeper(CuratorZookeeperClient.java:115)
>       at 
> org.apache.flink.shaded.org.apache.curator.framework.imps.CuratorFrameworkImpl.getZooKeeper(CuratorFrameworkImpl.java:477)
>       at 
> org.apache.flink.shaded.org.apache.curator.framework.imps.GetDataBuilderImpl$4.call(GetDataBuilderImpl.java:302)
>       at 
> org.apache.flink.shaded.org.apache.curator.framework.imps.GetDataBuilderImpl$4.call(GetDataBuilderImpl.java:291)
>       at 
> org.apache.flink.shaded.org.apache.curator.RetryLoop.callWithRetry(RetryLoop.java:107)
>       at 
> org.apache.flink.shaded.org.apache.curator.framework.imps.GetDataBuilderImpl.pathInForeground(GetDataBuilderImpl.java:288)
>       at 
> org.apache.flink.shaded.org.apache.curator.framework.imps.GetDataBuilderImpl.forPath(GetDataBuilderImpl.java:279)
>       at 
> org.apache.flink.shaded.org.apache.curator.framework.imps.GetDataBuilderImpl.forPath(GetDataBuilderImpl.java:41)
>       at 
> org.apache.flink.shaded.org.apache.curator.framework.recipes.shared.SharedValue.readValue(SharedValue.java:244)
>       at 
> org.apache.flink.shaded.org.apache.curator.framework.recipes.shared.SharedValue.access$100(SharedValue.java:44)
>       at 
> org.apache.flink.shaded.org.apache.curator.framework.recipes.shared.SharedValue$1.process(SharedValue.java:61)
>       at 
> org.apache.flink.shaded.org.apache.curator.framework.imps.NamespaceWatcher.process(NamespaceWatcher.java:67)
>       at 
> org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:522)
>       at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:498)
> We should have some retry logic there



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