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https://issues.apache.org/jira/browse/HDFS-15822?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17458392#comment-17458392
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tianhang tang commented on HDFS-15822:
--------------------------------------

[~ferhui] sry i forgot this patch...

I do use ignoredNodes in my change method:
{code:java}
+    if (clear) {
+      ignoredNodes.clear();
+    } {code}
That's because:

If the request of 1st round all failed, and the refetched location is not 
changed, HDFS client would not request the same nodes which are in the 
ignoreNodes. It just sleep time by time until reach the retry num, then throw a 
exception.

> Client retry mechanism may invalid when use hedgedRead
> ------------------------------------------------------
>
>                 Key: HDFS-15822
>                 URL: https://issues.apache.org/jira/browse/HDFS-15822
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: hdfs-client
>            Reporter: tianhang tang
>            Assignee: tianhang tang
>            Priority: Major
>         Attachments: HDFS-15822.001.patch
>
>
> Hedgedread uses ignoreNodes to ensure that multiple requests fall on 
> different nodes. But the ignoreNodes never been cleared. So if the request of 
> 1st round all failed, and the refetched location is not changed, HDFS client 
> would not request the same nodes which are in the ignoreNodes. It just sleep 
> time by time until reach the retry num, then throw a exception.



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