Mingliang Liu created HDFS-9379:
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Summary: 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
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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