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Posted to common-issues@hadoop.apache.org by "Íñigo Goiri (JIRA)" <ji...@apache.org> on 2019/05/13 18:47:00 UTC

[jira] [Updated] (HADOOP-16161) NetworkTopology#getWeightUsingNetworkLocation return unexpected result

     [ https://issues.apache.org/jira/browse/HADOOP-16161?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Íñigo Goiri updated HADOOP-16161:
---------------------------------
       Resolution: Fixed
     Hadoop Flags: Reviewed
    Fix Version/s: 3.3.0
           Status: Resolved  (was: Patch Available)

> NetworkTopology#getWeightUsingNetworkLocation return unexpected result
> ----------------------------------------------------------------------
>
>                 Key: HADOOP-16161
>                 URL: https://issues.apache.org/jira/browse/HADOOP-16161
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: net
>            Reporter: He Xiaoqiao
>            Assignee: He Xiaoqiao
>            Priority: Major
>             Fix For: 3.3.0
>
>         Attachments: HADOOP-16161.001.patch, HADOOP-16161.002.patch, HADOOP-16161.003.patch, HADOOP-16161.004.patch, HADOOP-16161.005.patch, HADOOP-16161.006.patch, HADOOP-16161.007.patch, HADOOP-16161.008.patch, HADOOP-16161.009.patch
>
>
> Consider the following scenario:
> 1. there are 4 slaves and topology like:
> Rack: /IDC/RACK1
>    hostname1
>    hostname2
> Rack: /IDC/RACK2
>    hostname3
>    hostname4
> 2. Reader from hostname1, and calculate weight between reader and [hostname1, hostname3, hostname4] by #getWeight, and their corresponding values are [0,4,4]
> 3. Reader from client which is not in the topology, and in the same IDC but in none rack of the topology, and calculate weight between reader and [hostname1, hostname3, hostname4] by #getWeightUsingNetworkLocation, and their corresponding values are [2,2,2]
> 4. Other different Reader can get the similar results.
> The weight result for case #3 is obviously not the expected value, the truth is [4,4,4]. this issue may cause reader not really following arrange: local -> local rack -> remote rack. 
> After dig the detailed implement, the root cause is #getWeightUsingNetworkLocation only calculate distance between Racks rather than hosts.
> I think we should add constant 2 to correct the weight of #getWeightUsingNetworkLocation.



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