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From Jeff Kubina <jeff.kub...@gmail.com>
Subject Re: Question about configuring the linux niceness of tablet servers?
Date Tue, 18 Aug 2015 21:33:12 GMT
> > I haven't heard of anybody setting the niceness of the Accumulo processes
> > before. Are you experiencing a lot of CPU contention on your nodes, such
> > that you need to prioritize processes?
>

Yes, we have had mapreduce jobs "lock out" the tserver so long that the
master removes them from its pool for not responding. But also when doing a
query from another service while the mapreduce jobs are maxed out I want to
make sure the tserver takes priority.


> > However, if you do this, I think you actually want HDFS to -2, Accumulo
> to -1,
> > and Mapreduce tasks 0 (you'll have to edit the system security limits to
> allow
> > niceness below 0 for non-root users).
> > Otherwise, you're lowering the priority, not increasing it (and lowering
> it
> > below other, normal user processes, since the default niceness is 0).
>

Agreed. That is what I wanted to do originally but it requires much more
reconfiguration. Ideally all OS root processes currently at 0 get reniced
to -2, HDFS to -2, Accumulo to -2, and mapreduce to -1 and all other user
processes stay at 0. Given the amount of threading a datanode does by
default it could lockout a tserver if its priority was lower, so I think
the HDFS and Accumulo should have equal priority.

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