[jira] [Commented] (KAFKA-3014) Integer overflow causes incorrect node iteration in leastLoadedNode()

["Ismael Juma (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-3014?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15064548#comment-15064548 ] 

Ismael Juma commented on KAFKA-3014:
------------------------------------

Nice catch!

> Integer overflow causes incorrect node iteration in leastLoadedNode() 
> ----------------------------------------------------------------------
>
>                 Key: KAFKA-3014
>                 URL: https://issues.apache.org/jira/browse/KAFKA-3014
>             Project: Kafka
>          Issue Type: Bug
>            Reporter: Jason Gustafson
>            Assignee: Jason Gustafson
>
> The leastLoadedNode() implementation iterates over all the known nodes to find a suitable candidate for sending metadata. The loop looks like this:
> {code}
> for (int i = 0; i < nodes.size(); i++) {
>   int idx = Utils.abs((this.nodeIndexOffset + i) % nodes.size());
>   Node node = nodes.get(idx);
>   ...
> }
> {code}
> Unfortunately, this doesn't handle integer overflow correctly, which can result in some nodes in the list being passed over. For example, if the size of the node list is 5 and the random offset is Integer.MAX_VALUE, then the loop will iterate over the following indices: 2, 3, 2, 1, 0. 
> In pathological cases, this can prevent the client from being able to connect to good nodes in order to refresh metadata.



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