[jira] [Resolved] (HADOOP-7822) Hadoop startup script has a race condition : this causes failures in datanodes status and stop commands

["Ravi Prakash (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HADOOP-7822?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ravi Prakash resolved HADOOP-7822.
----------------------------------
    Resolution: Fixed

This has probably been fixed as part of the shell script rewrite

> Hadoop startup script has a race condition : this causes failures in datanodes status and stop commands
> -------------------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-7822
>                 URL: https://issues.apache.org/jira/browse/HADOOP-7822
>             Project: Hadoop Common
>          Issue Type: Bug
>    Affects Versions: 0.20.1, 0.20.2, 0.20.205.0
>            Reporter: Rahul Jain
>
> The symptoms are the following:
> a) start-all.sh is able to start both hadoop dfs and map-reduce processes, assuming same grid nodes are used for dfs and map-reduce
> b) stop-all.sh stops map-reduce but fails to stop dfs processes (datanode tasks on grid nodes)  
>     Instead, the warning message 'no datanode to stop' is seen for all data nodes.
> c) The 'pid' files for datanode processes do not exist therefore the only way to stop datanode processes is to manually execute kill commands.
> The root cause of the issue appears to be in hadoop startup scripts. start-all.sh is really two parts:
> 1. start-dfs.sh : Start namenode and datanodes
> 2. start-mapred.sh: Jobtracker and task trackers.
> In this case, running start-dfs.sh did as expected and created the pid files for different datanodes. However, start-mapred.sh script did end up forcing another rsync from master to slaves, effectively wiping out the pid files stored under "pid" directory.



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