[ 
https://issues.apache.org/jira/browse/CURATOR-311?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15818125#comment-15818125
 ] 

ASF GitHub Bot commented on CURATOR-311:
----------------------------------------

Github user oza commented on a diff in the pull request:

    https://github.com/apache/curator/pull/193#discussion_r95565260
  
    --- Diff: 
curator-recipes/src/test/java/org/apache/curator/framework/recipes/shared/TestSharedCount.java
 ---
    @@ -381,12 +385,118 @@ public void processResult(CuratorFramework client, 
CuratorEvent event) throws Ex
                 }).forPath("/count");
                 flushDone.await(5, TimeUnit.SECONDS);
     
    -            Assert.assertEquals(2, numChangeEvents.get());
    +            Assert.assertEquals(numChangeEvents.get(), 3);
    --- End diff --
    
    This means this PR includes semantic change of countHasChanged callback: 
after reconnecting, countHasChanged() is called.


> SharedValue could hold stall data when quourm membership changes
> ----------------------------------------------------------------
>
>                 Key: CURATOR-311
>                 URL: https://issues.apache.org/jira/browse/CURATOR-311
>             Project: Apache Curator
>          Issue Type: Bug
>          Components: Recipes
>    Affects Versions: 3.1.0
>         Environment: Linux
>            Reporter: Jian Fang
>
> We run a Zookeeper 3.5.1-alpha quorum on EC2 instances and the quorum members 
> could be changed, for example, one peer could be replaced by a new EC2 
> instance due to EC2 instance termination. We use Apache Curator 3.1.0 as the 
> zookeeper client. During our testing, we found the SharedValue data structure 
> could hold stall data during and after one peer is replaced and thus led to 
> the system failure. 
> We look into the SharedValue code. Seems it always returns the value from an 
> in-memory reference variable and the value is only updated by a watcher. If 
> for any reason, the watch is lost, then the value would never get a chance to 
> be updated again.
>  
> Right now, we added a connection state listener to force SharedValue to call 
> readValue(), i.e., read the data from zookeeper directly, if the connection 
> state has been changed to RECONNECTED to work around this issue.
> It would be great if this issue could be fixed in Curator directly.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Reply via email to