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https://issues.apache.org/jira/browse/HADOOP-17222?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17183695#comment-17183695
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fanrui commented on HADOOP-17222:
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Hi [~liuml07], thanks for your comment.
The case you provided may happen. My idea is to only cache URI objects, and the
URL does not contain ip. From FlameGraph, we can see that create URI is the
most time-consuming operation, so caching URI can provide performance.
I have updated the code. Could you please review it, thank you.
[https://github.com/apache/hadoop/pull/2241]
> Create socket address combined with cache to speed up hdfs client choose
> DataNode
> ---------------------------------------------------------------------------------
>
> Key: HADOOP-17222
> URL: https://issues.apache.org/jira/browse/HADOOP-17222
> Project: Hadoop Common
> Issue Type: Improvement
> Components: common, hdfs-client
> Environment: HBase version: 2.1.0
> JVM: -Xmx2g -Xms2g
> hadoop hdfs version: 2.7.4
> disk:SSD
> OS:CentOS Linux release 7.4.1708 (Core)
> JMH Benchmark: @Fork(value = 1)
> @Warmup(iterations = 300)
> @Measurement(iterations = 300)
> Reporter: fanrui
> Priority: Major
> Attachments: After Optimization remark.png, After optimization.svg,
> Before Optimization remark.png, Before optimization.svg
>
>
> Note：Not only the hdfs client can get the current benefit, all callers of
> NetUtils.createSocketAddr will get the benefit. Just use hdfs client as an
> example.
>
> Hdfs client selects best DN for hdfs Block. method call stack:
> DFSInputStream.chooseDataNode -> getBestNodeDNAddrPair ->
> NetUtils.createSocketAddr
> NetUtils.createSocketAddr creates the corresponding InetSocketAddress based
> on the host and port. There are some heavier operations in the
> NetUtils.createSocketAddr method, for example: URI.create(target), so
> NetUtils.createSocketAddr takes more time to execute.
> The following is my performance report. The report is based on HBase calling
> hdfs. HBase is a high-frequency access client for hdfs, because HBase read
> operations often access a small DataBlock (about 64k) instead of the entire
> HFile. In the case of high frequency access, the NetUtils.createSocketAddr
> method is time-consuming.
> h3. Test Environment：
>
> {code:java}
> HBase version: 2.1.0
> JVM: -Xmx2g -Xms2g
> hadoop hdfs version: 2.7.4
> disk:SSD
> OS:CentOS Linux release 7.4.1708 (Core)
> JMH Benchmark: @Fork(value = 1)
> @Warmup(iterations = 300)
> @Measurement(iterations = 300)
> {code}
> h4. Before Optimization FlameGraph:
> In the figure, we can see that DFSInputStream.getBestNodeDNAddrPair accounts
> for 4.86% of the entire CPU, and the creation of URIs accounts for a larger
> proportion.
> !Before Optimization remark.png!
> h3. Optimization ideas:
> NetUtils.createSocketAddr creates InetSocketAddress based on host and port.
> Here we can add Cache to InetSocketAddress. The key of Cache is host and
> port, and the value is InetSocketAddress.
> h4. After Optimization FlameGraph:
> In the figure, we can see that DFSInputStream.getBestNodeDNAddrPair accounts
> for 0.54% of the entire CPU. Here, ConcurrentHashMap is used as the Cache,
> and the ConcurrentHashMap.get() method gets data from the Cache. The CPU
> usage of DFSInputStream.getBestNodeDNAddrPair has been optimized from 4.86%
> to 0.54%.
> !After Optimization remark.png!
> h3. Original FlameGraph link:
> [Before
> Optimization|https://drive.google.com/file/d/133L5m75u2tu_KgKfGHZLEUzGR0XAfUl6/view?usp=sharing]
> [After Optimization
> FlameGraph|https://drive.google.com/file/d/133L5m75u2tu_KgKfGHZLEUzGR0XAfUl6/view?usp=sharing]
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