> > 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.
