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https://issues.apache.org/jira/browse/HDFS-9379?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mingliang Liu updated HDFS-9379:
--------------------------------
    Attachment: HDFS-9379.000.patch

> Make NNThroughputBenchmark support more than 10 numThreads
> ----------------------------------------------------------
>
>                 Key: HDFS-9379
>                 URL: https://issues.apache.org/jira/browse/HDFS-9379
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: namenode
>            Reporter: Mingliang Liu
>            Assignee: Mingliang Liu
>         Attachments: HDFS-9379.000.patch
>
>
> Currently, the {{NNThroughputBenchmark}} relies on sorted {{datanodes}} array 
> in the lexicographical order of datanode's {{xferAddr}}.
> * There is an assertion of datanode's {{xferAddr}} lexicographical order when 
> filling the {{datanodes}}, see [the 
> code|https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/NNThroughputBenchmark.java#L1152].
> * When searching the datanode by {{DatanodeInfo}}, it uses binary search 
> against the {{datanodes}} array, see [the 
> code|https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/NNThroughputBenchmark.java#L1187]
> In {{DatanodeID}}, the {{xferAddr}} is defined as {{host:port}}. In 
> {{NNThroughputBenchmark}}, the port is simply _the index of the tiny 
> datanode_ plus one.
> The problem here is that, when there are more than 9 tiny datanodes 
> ({{numThreads}}), the lexicographical order of datanode's {{xferAddr}} will 
> be invalid as the string value of datanode index is not in lexicographical 
> order any more. For example, 
> {code}
> ...
> 192.168.54.40:8
> 192.168.54.40:9
> 192.168.54.40:10
> 192.168.54.40:11
> ...
> {code}
> {{192.168.54.40:9}} is greater than {{192.168.54.40:10}}. The assertion will 
> fail and the binary search won't work.
> The simple fix is to calculate the datanode index by port directly, instead 
> of using binary search.



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