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From Jeff Kubina <>
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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