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https://issues.apache.org/jira/browse/BIGTOP-456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13230746#comment-13230746
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Bruno Mahé commented on BIGTOP-456:
-----------------------------------
This is why /var/run/hadoop belongs to the group hadoop and is writable. So
both daemons can write to it.
By default it is set to:
{noformat}drwxrwxr-x 2 root hadoop 4096 Mar 15 14:31 hadoop{noformat}
And I see the home dir of these users not being set to /var/run/hadoop but
rather /usr/lib/hadoop:
{noformat}
[root@172 ~]# grep hadoop /etc/passwd
mapred:x:497:494:Hadoop MapReduce:/usr/lib/hadoop:/bin/bash
hdfs:x:496:495:Hadoop HDFS:/usr/lib/hadoop:/bin/bash
{noformat}
But I agree that separating the pid dir of these 2 users would make sense.
Regarding /run vs /var/run, given we also strive to support older GNU/Linux
distributions such as CentOS/RHEL 5 and others, I would rather stay on /var/run
for consistency.
Unless there is a compelling reason to have a specific packaging path for cases
where /run is available. But that would make maintenance of the packages more
complex, so it has to be worth it.
> Consider splitting homedir between mapred and hdfs users?
> ---------------------------------------------------------
>
> Key: BIGTOP-456
> URL: https://issues.apache.org/jira/browse/BIGTOP-456
> Project: Bigtop
> Issue Type: Improvement
> Components: General
> Affects Versions: 0.1.0
> Environment: RPMs
> Reporter: Harsh J
> Priority: Minor
>
> Both "mapred" and "hdfs" users have the same home dir.
> A user reported having some problems with their config management system
> overwriting the "mapred" user permissions of the PID directory (Which is also
> its homedir) with those of the "hdfs" user (Same homedir as "mapred" user),
> which causes the tasktracker process to fail to start, since it now cannot
> write to the PID dir.
> Although the config system can be fixed not to do that, if both users had
> separate home dirs, this would not have been a problem, and the separation
> would have only been logical.
> I think after the username separation Hadoop has had in packaging terms, the
> homedir split does make sense.
> Its just 1/0.22 versions of Hadoop and their packages that could be affected
> by this.
> Presently, for 0.23+, I think we have /var/run/hadoop/ for all things HDFS
> (Should we rename?) and /var/run/yarn/ for all things MapReduce2 which makes
> sense and should be good enough.
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